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/*
 * linux/drivers/ide/ide-tape.c        Version 1.17a    Jan, 2001
 *
 * Copyright (C) 1995 - 1999 Gadi Oxman <gadio@netvision.net.il>
 *
 * $Header$
 *
 * This driver was constructed as a student project in the software laboratory
 * of the faculty of electrical engineering in the Technion - Israel's
 * Institute Of Technology, with the guide of Avner Lottem and Dr. Ilana David.
 *
 * It is hereby placed under the terms of the GNU general public license.
 * (See linux/COPYING).
 */
 
/*
 * IDE ATAPI streaming tape driver.
 *
 * This driver is a part of the Linux ide driver and works in co-operation
 * with linux/drivers/block/ide.c.
 *
 * The driver, in co-operation with ide.c, basically traverses the 
 * request-list for the block device interface. The character device
 * interface, on the other hand, creates new requests, adds them
 * to the request-list of the block device, and waits for their completion.
 *
 * Pipelined operation mode is now supported on both reads and writes.
 *
 * The block device major and minor numbers are determined from the
 * tape's relative position in the ide interfaces, as explained in ide.c.
 *
 * The character device interface consists of the following devices:
 *
 * ht0        major 37, minor 0    first  IDE tape, rewind on close.
 * ht1        major 37, minor 1    second IDE tape, rewind on close.
 * ...
 * nht0        major 37, minor 128    first  IDE tape, no rewind on close.
 * nht1        major 37, minor 129    second IDE tape, no rewind on close.
 * ...
 *
 * Run linux/scripts/MAKEDEV.ide to create the above entries.
 *
 * The general magnetic tape commands compatible interface, as defined by
 * include/linux/mtio.h, is accessible through the character device.
 *
 * General ide driver configuration options, such as the interrupt-unmask
 * flag, can be configured by issuing an ioctl to the block device interface,
 * as any other ide device.
 *
 * Our own ide-tape ioctl's can be issued to either the block device or
 * the character device interface.
 *
 * Maximal throughput with minimal bus load will usually be achieved in the
 * following scenario:
 *
 *    1.    ide-tape is operating in the pipelined operation mode.
 *    2.    No buffering is performed by the user backup program.
 *
 * Testing was done with a 2 GB CONNER CTMA 4000 IDE ATAPI Streaming Tape Drive.
 * 
 * Ver 0.1   Nov  1 95   Pre-working code :-)
 * Ver 0.2   Nov 23 95   A short backup (few megabytes) and restore procedure
 *                        was successful ! (Using tar cvf ... on the block
 *                        device interface).
 *                       A longer backup resulted in major swapping, bad
 *                        overall Linux performance and eventually failed as
 *                        we received non serial read-ahead requests from the
 *                        buffer cache.
 * Ver 0.3   Nov 28 95   Long backups are now possible, thanks to the
 *                        character device interface. Linux's responsiveness
 *                        and performance doesn't seem to be much affected
 *                        from the background backup procedure.
 *                       Some general mtio.h magnetic tape operations are
 *                        now supported by our character device. As a result,
 *                        popular tape utilities are starting to work with
 *                        ide tapes :-)
 *                       The following configurations were tested:
 *                           1. An IDE ATAPI TAPE shares the same interface
 *                              and irq with an IDE ATAPI CDROM.
 *                            2. An IDE ATAPI TAPE shares the same interface
 *                                 and irq with a normal IDE disk.
 *                        Both configurations seemed to work just fine !
 *                        However, to be on the safe side, it is meanwhile
 *                        recommended to give the IDE TAPE its own interface
 *                        and irq.
 *                       The one thing which needs to be done here is to
 *                        add a "request postpone" feature to ide.c,
 *                        so that we won't have to wait for the tape to finish
 *                        performing a long media access (DSC) request (such
 *                        as a rewind) before we can access the other device
 *                        on the same interface. This effect doesn't disturb
 *                        normal operation most of the time because read/write
 *                        requests are relatively fast, and once we are
 *                        performing one tape r/w request, a lot of requests
 *                        from the other device can be queued and ide.c will
 *              service all of them after this single tape request.
 * Ver 1.0   Dec 11 95   Integrated into Linux 1.3.46 development tree.
 *                       On each read / write request, we now ask the drive
 *                        if we can transfer a constant number of bytes
 *                        (a parameter of the drive) only to its buffers,
 *                        without causing actual media access. If we can't,
 *                        we just wait until we can by polling the DSC bit.
 *                        This ensures that while we are not transferring
 *                        more bytes than the constant referred to above, the
 *                        interrupt latency will not become too high and
 *                        we won't cause an interrupt timeout, as happened
 *                        occasionally in the previous version.
 *                       While polling for DSC, the current request is
 *                        postponed and ide.c is free to handle requests from
 *                        the other device. This is handled transparently to
 *                        ide.c. The hwgroup locking method which was used
 *                        in the previous version was removed.
 *                       Use of new general features which are provided by
 *                        ide.c for use with atapi devices.
 *                        (Programming done by Mark Lord)
 *                       Few potential bug fixes (Again, suggested by Mark)
 *                       Single character device data transfers are now
 *                        not limited in size, as they were before.
 *                       We are asking the tape about its recommended
 *                        transfer unit and send a larger data transfer
 *                        as several transfers of the above size.
 *                        For best results, use an integral number of this
 *                        basic unit (which is shown during driver
 *                        initialization). I will soon add an ioctl to get
 *                        this important parameter.
 *                       Our data transfer buffer is allocated on startup,
 *                        rather than before each data transfer. This should
 *                        ensure that we will indeed have a data buffer.
 * Ver 1.1   Dec 14 95   Fixed random problems which occurred when the tape
 *                        shared an interface with another device.
 *                        (poll_for_dsc was a complete mess).
 *                       Removed some old (non-active) code which had
 *                        to do with supporting buffer cache originated
 *                        requests.
 *                       The block device interface can now be opened, so
 *                        that general ide driver features like the unmask
 *                        interrupts flag can be selected with an ioctl.
 *                        This is the only use of the block device interface.
 *                       New fast pipelined operation mode (currently only on
 *                        writes). When using the pipelined mode, the
 *                        throughput can potentially reach the maximum
 *                        tape supported throughput, regardless of the
 *                        user backup program. On my tape drive, it sometimes
 *                        boosted performance by a factor of 2. Pipelined
 *                        mode is enabled by default, but since it has a few
 *                        downfalls as well, you may want to disable it.
 *                        A short explanation of the pipelined operation mode
 *                        is available below.
 * Ver 1.2   Jan  1 96   Eliminated pipelined mode race condition.
 *                       Added pipeline read mode. As a result, restores
 *                        are now as fast as backups.
 *                       Optimized shared interface behavior. The new behavior
 *                        typically results in better IDE bus efficiency and
 *                        higher tape throughput.
 *                       Pre-calculation of the expected read/write request
 *                        service time, based on the tape's parameters. In
 *                        the pipelined operation mode, this allows us to
 *                        adjust our polling frequency to a much lower value,
 *                        and thus to dramatically reduce our load on Linux,
 *                        without any decrease in performance.
 *                       Implemented additional mtio.h operations.
 *                       The recommended user block size is returned by
 *                        the MTIOCGET ioctl.
 *                       Additional minor changes.
 * Ver 1.3   Feb  9 96   Fixed pipelined read mode bug which prevented the
 *                        use of some block sizes during a restore procedure.
 *                       The character device interface will now present a
 *                        continuous view of the media - any mix of block sizes
 *                        during a backup/restore procedure is supported. The
 *                        driver will buffer the requests internally and
 *                        convert them to the tape's recommended transfer
 *                        unit, making performance almost independent of the
 *                        chosen user block size.
 *                       Some improvements in error recovery.
 *                       By cooperating with ide-dma.c, bus mastering DMA can
 *                        now sometimes be used with IDE tape drives as well.
 *                        Bus mastering DMA has the potential to dramatically
 *                        reduce the CPU's overhead when accessing the device,
 *                        and can be enabled by using hdparm -d1 on the tape's
 *                        block device interface. For more info, read the
 *                        comments in ide-dma.c.
 * Ver 1.4   Mar 13 96   Fixed serialize support.
 * Ver 1.5   Apr 12 96   Fixed shared interface operation, broken in 1.3.85.
 *                       Fixed pipelined read mode inefficiency.
 *                       Fixed nasty null dereferencing bug.
 * Ver 1.6   Aug 16 96   Fixed FPU usage in the driver.
 *                       Fixed end of media bug.
 * Ver 1.7   Sep 10 96   Minor changes for the CONNER CTT8000-A model.
 * Ver 1.8   Sep 26 96   Attempt to find a better balance between good
 *                        interactive response and high system throughput.
 * Ver 1.9   Nov  5 96   Automatically cross encountered filemarks rather
 *                        than requiring an explicit FSF command.
 *                       Abort pending requests at end of media.
 *                       MTTELL was sometimes returning incorrect results.
 *                       Return the real block size in the MTIOCGET ioctl.
 *                       Some error recovery bug fixes.
 * Ver 1.10  Nov  5 96   Major reorganization.
 *                       Reduced CPU overhead a bit by eliminating internal
 *                        bounce buffers.
 *                       Added module support.
 *                       Added multiple tape drives support.
 *                       Added partition support.
 *                       Rewrote DSC handling.
 *                       Some portability fixes.
 *                       Removed ide-tape.h.
 *                       Additional minor changes.
 * Ver 1.11  Dec  2 96   Bug fix in previous DSC timeout handling.
 *                       Use ide_stall_queue() for DSC overlap.
 *                       Use the maximum speed rather than the current speed
 *                        to compute the request service time.
 * Ver 1.12  Dec  7 97   Fix random memory overwriting and/or last block data
 *                        corruption, which could occur if the total number
 *                        of bytes written to the tape was not an integral
 *                        number of tape blocks.
 *                       Add support for INTERRUPT DRQ devices.
 * Ver 1.13  Jan  2 98   Add "speed == 0" work-around for HP COLORADO 5GB
 * Ver 1.14  Dec 30 98   Partial fixes for the Sony/AIWA tape drives.
 *                       Replace cli()/sti() with hwgroup spinlocks.
 * Ver 1.15  Mar 25 99   Fix SMP race condition by replacing hwgroup
 *                        spinlock with private per-tape spinlock.
 * Ver 1.16  Sep  1 99   Add OnStream tape support.
 *                       Abort read pipeline on EOD.
 *                       Wait for the tape to become ready in case it returns
 *                        "in the process of becoming ready" on open().
 *                       Fix zero padding of the last written block in
 *                        case the tape block size is larger than PAGE_SIZE.
 *                       Decrease the default disconnection time to tn.
 * Ver 1.16e Oct  3 99   Minor fixes.
 * Ver 1.16e1 Oct 13 99  Patches by Arnold Niessen,
 *                          niessen@iae.nl / arnold.niessen@philips.com
 *                   GO-1)  Undefined code in idetape_read_position
 *                according to Gadi's email
 *                   AJN-1) Minor fix asc == 11 should be asc == 0x11
 *                               in idetape_issue_packet_command (did effect
 *                               debugging output only)
 *                   AJN-2) Added more debugging output, and
 *                              added ide-tape: where missing. I would also
 *                like to add tape->name where possible
 *                   AJN-3) Added different debug_level's 
 *                              via /proc/ide/hdc/settings
 *                 "debug_level" determines amount of debugging output;
 *                 can be changed using /proc/ide/hdx/settings
 *                 0 : almost no debugging output
 *                 1 : 0+output errors only
 *                 2 : 1+output all sensekey/asc
 *                 3 : 2+follow all chrdev related procedures
 *                 4 : 3+follow all procedures
 *                 5 : 4+include pc_stack rq_stack info
 *                 6 : 5+USE_COUNT updates
 *                   AJN-4) Fixed timeout for retension in idetape_queue_pc_tail
 *                from 5 to 10 minutes
 *                   AJN-5) Changed maximum number of blocks to skip when
 *                              reading tapes with multiple consecutive write
 *                              errors from 100 to 1000 in idetape_get_logical_blk
 *                   Proposed changes to code:
 *                   1) output "logical_blk_num" via /proc
 *                   2) output "current_operation" via /proc
 *                   3) Either solve or document the fact that `mt rewind' is
 *                      required after reading from /dev/nhtx to be
 *            able to rmmod the idetape module;
 *            Also, sometimes an application finishes but the
 *            device remains `busy' for some time. Same cause ?
 *                   Proposed changes to release-notes:
 *             4) write a simple `quickstart' section in the
 *                      release notes; I volunteer if you don't want to
 *              5) include a pointer to video4linux in the doc
 *                      to stimulate video applications
 *                   6) release notes lines 331 and 362: explain what happens
 *            if the application data rate is higher than 1100 KB/s; 
 *            similar approach to lower-than-500 kB/s ?
 *             7) 6.6 Comparison; wouldn't it be better to allow different 
 *            strategies for read and write ?
 *            Wouldn't it be better to control the tape buffer
 *            contents instead of the bandwidth ?
 *             8) line 536: replace will by would (if I understand
 *            this section correctly, a hypothetical and unwanted situation
 *             is being described)
 * Ver 1.16f Dec 15 99   Change place of the secondary OnStream header frames.
 * Ver 1.17  Nov 2000 / Jan 2001  Marcel Mol, marcel@mesa.nl
 *            - Add idetape_onstream_mode_sense_tape_parameter_page
 *              function to get tape capacity in frames: tape->capacity.
 *            - Add support for DI-50 drives( or any DI- drive).
 *            - 'workaround' for read error/blank block arround block 3000.
 *            - Implement Early warning for end of media for Onstream.
 *            - Cosmetic code changes for readability.
 *            - Idetape_position_tape should not use SKIP bit during
 *              Onstream read recovery.
 *            - Add capacity, logical_blk_num and first/last_frame_position
 *              to /proc/ide/hd?/settings.
 *            - Module use count was gone in the Linux 2.4 driver.
 * Ver 1.17a Apr 2001 Willem Riede osst@riede.org
 *             - Get drive's actual block size from mode sense block descriptor
 *             - Limit size of pipeline
 *
 * Here are some words from the first releases of hd.c, which are quoted
 * in ide.c and apply here as well:
 *
 * | Special care is recommended.  Have Fun!
 *
 */

/*
 * An overview of the pipelined operation mode.
 *
 * In the pipelined write mode, we will usually just add requests to our
 * pipeline and return immediately, before we even start to service them. The
 * user program will then have enough time to prepare the next request while
 * we are still busy servicing previous requests. In the pipelined read mode,
 * the situation is similar - we add read-ahead requests into the pipeline,
 * before the user even requested them.
 *
 * The pipeline can be viewed as a "safety net" which will be activated when
 * the system load is high and prevents the user backup program from keeping up
 * with the current tape speed. At this point, the pipeline will get
 * shorter and shorter but the tape will still be streaming at the same speed.
 * Assuming we have enough pipeline stages, the system load will hopefully
 * decrease before the pipeline is completely empty, and the backup program
 * will be able to "catch up" and refill the pipeline again.
 * 
 * When using the pipelined mode, it would be best to disable any type of
 * buffering done by the user program, as ide-tape already provides all the
 * benefits in the kernel, where it can be done in a more efficient way.
 * As we will usually not block the user program on a request, the most
 * efficient user code will then be a simple read-write-read-... cycle.
 * Any additional logic will usually just slow down the backup process.
 *
 * Using the pipelined mode, I get a constant over 400 KBps throughput,
 * which seems to be the maximum throughput supported by my tape.
 *
 * However, there are some downfalls:
 *
 *    1.    We use memory (for data buffers) in proportional to the number
 *        of pipeline stages (each stage is about 26 KB with my tape).
 *    2.    In the pipelined write mode, we cheat and postpone error codes
 *        to the user task. In read mode, the actual tape position
 *        will be a bit further than the last requested block.
 *
 * Concerning (1):
 *
 *    1.    We allocate stages dynamically only when we need them. When
 *        we don't need them, we don't consume additional memory. In
 *        case we can't allocate stages, we just manage without them
 *        (at the expense of decreased throughput) so when Linux is
 *        tight in memory, we will not pose additional difficulties.
 *
 *    2.    The maximum number of stages (which is, in fact, the maximum
 *        amount of memory) which we allocate is limited by the compile
 *        time parameter IDETAPE_MAX_PIPELINE_STAGES.
 *
 *    3.    The maximum number of stages is a controlled parameter - We
 *        don't start from the user defined maximum number of stages
 *        but from the lower IDETAPE_MIN_PIPELINE_STAGES (again, we
 *        will not even allocate this amount of stages if the user
 *        program can't handle the speed). We then implement a feedback
 *        loop which checks if the pipeline is empty, and if it is, we
 *        increase the maximum number of stages as necessary until we
 *        reach the optimum value which just manages to keep the tape
 *        busy with minimum allocated memory or until we reach
 *        IDETAPE_MAX_PIPELINE_STAGES.
 *
 * Concerning (2):
 *
 *    In pipelined write mode, ide-tape can not return accurate error codes
 *    to the user program since we usually just add the request to the
 *      pipeline without waiting for it to be serviced. In case an error
 *      occurs, I will report it on the next user request.
 *
 *    In the pipelined read mode, subsequent read requests or forward
 *    filemark spacing will perform correctly, as we preserve all blocks
 *    and filemarks which we encountered during our excess read-ahead.
 * 
 *    For accurate tape positioning and error reporting, disabling
 *    pipelined mode might be the best option.
 *
 * You can enable/disable/tune the pipelined operation mode by adjusting
 * the compile time parameters below.
 */

/*
 *    Possible improvements.
 *
 *    1.    Support for the ATAPI overlap protocol.
 *
 *        In order to maximize bus throughput, we currently use the DSC
 *        overlap method which enables ide.c to service requests from the
 *        other device while the tape is busy executing a command. The
 *        DSC overlap method involves polling the tape's status register
 *        for the DSC bit, and servicing the other device while the tape
 *        isn't ready.
 *
 *        In the current QIC development standard (December 1995),
 *        it is recommended that new tape drives will *in addition* 
 *        implement the ATAPI overlap protocol, which is used for the
 *        same purpose - efficient use of the IDE bus, but is interrupt
 *        driven and thus has much less CPU overhead.
 *
 *        ATAPI overlap is likely to be supported in most new ATAPI
 *        devices, including new ATAPI cdroms, and thus provides us
 *        a method by which we can achieve higher throughput when
 *        sharing a (fast) ATA-2 disk with any (slow) new ATAPI device.
 */

#define IDETAPE_VERSION "1.17a"

#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/major.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/errno.h>
#include <linux/genhd.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/ide.h>
#include <linux/smp_lock.h>
#include <linux/completion.h>

#include <asm/byteorder.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/unaligned.h>
#include <asm/bitops.h>


#define NO_LONGER_REQUIRED    (1)

/*
 *    OnStream support
 */
#define ONSTREAM_DEBUG        (0)
#define OS_CONFIG_PARTITION    (0xff)
#define OS_DATA_PARTITION    (0)
#define OS_PARTITION_VERSION    (1)
#define OS_EW            300
#define OS_ADR_MINREV        2

#define OS_DATA_STARTFRAME1    20
#define OS_DATA_ENDFRAME1    2980
/*
 * partition
 */
typedef struct os_partition_s {
    __u8    partition_num;
    __u8    par_desc_ver;
    __u16    wrt_pass_cntr;
    __u32    first_frame_addr;
    __u32    last_frame_addr;
    __u32    eod_frame_addr;
} os_partition_t;

/*
 * DAT entry
 */
typedef struct os_dat_entry_s {
    __u32    blk_sz;
    __u16    blk_cnt;
    __u8    flags;
    __u8    reserved;
} os_dat_entry_t;

/*
 * DAT
 */
#define OS_DAT_FLAGS_DATA    (0xc)
#define OS_DAT_FLAGS_MARK    (0x1)

typedef struct os_dat_s {
    __u8        dat_sz;
    __u8        reserved1;
    __u8        entry_cnt;
    __u8        reserved3;
    os_dat_entry_t    dat_list[16];
} os_dat_t;

/*
 * Frame types
 */
#define OS_FRAME_TYPE_FILL    (0)
#define OS_FRAME_TYPE_EOD    (1 << 0)
#define OS_FRAME_TYPE_MARKER    (1 << 1)
#define OS_FRAME_TYPE_HEADER    (1 << 3)
#define OS_FRAME_TYPE_DATA    (1 << 7)

/*
 * AUX
 */
typedef struct os_aux_s {
    __u32        format_id;        /* hardware compability AUX is based on */
    char        application_sig[4];    /* driver used to write this media */
    __u32        hdwr;            /* reserved */
    __u32        update_frame_cntr;    /* for configuration frame */
    __u8        frame_type;
    __u8        frame_type_reserved;
    __u8        reserved_18_19[2];
    os_partition_t    partition;
    __u8        reserved_36_43[8];
    __u32        frame_seq_num;
    __u32        logical_blk_num_high;
    __u32        logical_blk_num;
    os_dat_t    dat;
    __u8        reserved188_191[4];
    __u32        filemark_cnt;
    __u32        phys_fm;
    __u32        last_mark_addr;
    __u8        reserved204_223[20];

    /*
     * __u8        app_specific[32];
     *
     * Linux specific fields:
     */
     __u32        next_mark_addr;        /* when known, points to next marker */
     __u8        linux_specific[28];

    __u8        reserved_256_511[256];
} os_aux_t;

typedef struct os_header_s {
    char        ident_str[8];
    __u8        major_rev;
    __u8        minor_rev;
    __u8        reserved10_15[6];
    __u8        par_num;
    __u8        reserved1_3[3];
    os_partition_t    partition;
} os_header_t;

/*
 *    OnStream Tape Parameters Page
 */
typedef struct {
    unsigned    page_code    :6;    /* Page code - Should be 0x2b */
    unsigned    reserved1_6    :1;
    unsigned    ps        :1;
    __u8        reserved2;
    __u8        density;        /* kbpi */
    __u8        reserved3,reserved4;
    __u16        segtrk;                 /* segment of per track */
    __u16        trks;                   /* tracks per tape */
    __u8        reserved5,reserved6,reserved7,reserved8,reserved9,reserved10;
} onstream_tape_paramtr_page_t;

/*
 * OnStream ADRL frame
 */
#define OS_FRAME_SIZE    (32 * 1024 + 512)
#define OS_DATA_SIZE    (32 * 1024)
#define OS_AUX_SIZE    (512)

/*
 * internal error codes for onstream
 */
#define OS_PART_ERROR    2
#define OS_WRITE_ERROR   1

#include <linux/mtio.h>

/**************************** Tunable parameters *****************************/


/*
 *    Pipelined mode parameters.
 *
 *    We try to use the minimum number of stages which is enough to
 *    keep the tape constantly streaming. To accomplish that, we implement
 *    a feedback loop around the maximum number of stages:
 *
 *    We start from MIN maximum stages (we will not even use MIN stages
 *      if we don't need them), increment it by RATE*(MAX-MIN)
 *    whenever we sense that the pipeline is empty, until we reach
 *    the optimum value or until we reach MAX.
 *
 *    Setting the following parameter to 0 will disable the pipelined mode.
 */
#define IDETAPE_MIN_PIPELINE_STAGES    200
#define IDETAPE_MAX_PIPELINE_STAGES    400
#define IDETAPE_INCREASE_STAGES_RATE     20

/*
 *    The following are used to debug the driver:
 *
 *    Setting IDETAPE_DEBUG_INFO to 1 will report device capabilities.
 *    Setting IDETAPE_DEBUG_LOG to 1 will log driver flow control.
 *    Setting IDETAPE_DEBUG_BUGS to 1 will enable self-sanity checks in
 *    some places.
 *
 *    Setting them to 0 will restore normal operation mode:
 *
 *        1.    Disable logging normal successful operations.
 *        2.    Disable self-sanity checks.
 *        3.    Errors will still be logged, of course.
 *
 *    All the #if DEBUG code will be removed some day, when the driver
 *    is verified to be stable enough. This will make it much more
 *    esthetic.
 */
#define IDETAPE_DEBUG_INFO        1
#define IDETAPE_DEBUG_LOG        1
#define IDETAPE_DEBUG_LOG_VERBOSE    0
#define IDETAPE_DEBUG_BUGS        1

/*
 *    After each failed packet command we issue a request sense command
 *    and retry the packet command IDETAPE_MAX_PC_RETRIES times.
 *
 *    Setting IDETAPE_MAX_PC_RETRIES to 0 will disable retries.
 */
#define IDETAPE_MAX_PC_RETRIES        3

/*
 *    With each packet command, we allocate a buffer of
 *    IDETAPE_PC_BUFFER_SIZE bytes. This is used for several packet
 *    commands (Not for READ/WRITE commands).
 */
#define IDETAPE_PC_BUFFER_SIZE        256

/*
 *    In various places in the driver, we need to allocate storage
 *    for packet commands and requests, which will remain valid while
 *    we leave the driver to wait for an interrupt or a timeout event.
 */
#define IDETAPE_PC_STACK        (10 + IDETAPE_MAX_PC_RETRIES)

/*
 *    Some tape drives require a long irq timeout
 */
#define IDETAPE_WAIT_CMD        (60*HZ)

/*
 *    The following parameter is used to select the point in the internal
 *    tape fifo in which we will start to refill the buffer. Decreasing
 *    the following parameter will improve the system's latency and
 *    interactive response, while using a high value might improve sytem
 *    throughput.
 */
#define IDETAPE_FIFO_THRESHOLD         2

/*
 *    DSC polling parameters.
 *
 *    Polling for DSC (a single bit in the status register) is a very
 *    important function in ide-tape. There are two cases in which we
 *    poll for DSC:
 *
 *    1.    Before a read/write packet command, to ensure that we
 *        can transfer data from/to the tape's data buffers, without
 *        causing an actual media access. In case the tape is not
 *        ready yet, we take out our request from the device
 *        request queue, so that ide.c will service requests from
 *        the other device on the same interface meanwhile.
 *
 *    2.    After the successful initialization of a "media access
 *        packet command", which is a command which can take a long
 *        time to complete (it can be several seconds or even an hour).
 *
 *        Again, we postpone our request in the middle to free the bus
 *        for the other device. The polling frequency here should be
 *        lower than the read/write frequency since those media access
 *        commands are slow. We start from a "fast" frequency -
 *        IDETAPE_DSC_MA_FAST (one second), and if we don't receive DSC
 *        after IDETAPE_DSC_MA_THRESHOLD (5 minutes), we switch it to a
 *        lower frequency - IDETAPE_DSC_MA_SLOW (1 minute).
 *
 *    We also set a timeout for the timer, in case something goes wrong.
 *    The timeout should be longer then the maximum execution time of a
 *    tape operation.
 */
 
/*
 *    DSC timings.
 */
#define IDETAPE_DSC_RW_MIN        5*HZ/100    /* 50 msec */
#define IDETAPE_DSC_RW_MAX        40*HZ/100    /* 400 msec */
#define IDETAPE_DSC_RW_TIMEOUT        2*60*HZ        /* 2 minutes */
#define IDETAPE_DSC_MA_FAST        2*HZ        /* 2 seconds */
#define IDETAPE_DSC_MA_THRESHOLD    5*60*HZ        /* 5 minutes */
#define IDETAPE_DSC_MA_SLOW        30*HZ        /* 30 seconds */
#define IDETAPE_DSC_MA_TIMEOUT        2*60*60*HZ    /* 2 hours */

/*************************** End of tunable parameters ***********************/

/*
 *    Debugging/Performance analysis
 *
 *    I/O trace support
 */
#define USE_IOTRACE    0
#if USE_IOTRACE
#include <linux/io_trace.h>
#define IO_IDETAPE_FIFO    500
#endif

/*
 *    Read/Write error simulation
 */
#define SIMULATE_ERRORS            0

/*
 *    For general magnetic tape device compatibility.
 */
typedef enum {
    idetape_direction_none,
    idetape_direction_read,
    idetape_direction_write
} idetape_chrdev_direction_t;

/*
 *    Our view of a packet command.
 */
typedef struct idetape_packet_command_s {
    u8 c[12];                /* Actual packet bytes */
    int retries;                /* On each retry, we increment retries */
    int error;                /* Error code */
    int request_transfer;            /* Bytes to transfer */
    int actually_transferred;        /* Bytes actually transferred */
    int buffer_size;            /* Size of our data buffer */
    struct buffer_head *bh;
    char *b_data;
    int b_count;
    byte *buffer;                /* Data buffer */
    byte *current_position;            /* Pointer into the above buffer */
    ide_startstop_t (*callback) (ide_drive_t *);    /* Called when this packet command is completed */
    byte pc_buffer[IDETAPE_PC_BUFFER_SIZE];    /* Temporary buffer */
    unsigned long flags;            /* Status/Action bit flags: long for set_bit */
} idetape_pc_t;

/*
 *    Packet command flag bits.
 */
#define    PC_ABORT            0    /* Set when an error is considered normal - We won't retry */
#define PC_WAIT_FOR_DSC            1    /* 1 When polling for DSC on a media access command */
#define PC_DMA_RECOMMENDED        2    /* 1 when we prefer to use DMA if possible */
#define    PC_DMA_IN_PROGRESS        3    /* 1 while DMA in progress */
#define    PC_DMA_ERROR            4    /* 1 when encountered problem during DMA */
#define    PC_WRITING            5    /* Data direction */

/*
 *    Capabilities and Mechanical Status Page
 */
typedef struct {
    unsigned    page_code    :6;    /* Page code - Should be 0x2a */
    __u8        reserved0_6    :1;
    __u8        ps        :1;    /* parameters saveable */
    __u8        page_length;        /* Page Length - Should be 0x12 */
    __u8        reserved2, reserved3;
    unsigned    ro        :1;    /* Read Only Mode */
    unsigned    reserved4_1234    :4;
    unsigned    sprev        :1;    /* Supports SPACE in the reverse direction */
    unsigned    reserved4_67    :2;
    unsigned    reserved5_012    :3;
    unsigned    efmt        :1;    /* Supports ERASE command initiated formatting */
    unsigned    reserved5_4    :1;
    unsigned    qfa        :1;    /* Supports the QFA two partition formats */
    unsigned    reserved5_67    :2;
    unsigned    lock        :1;    /* Supports locking the volume */
    unsigned    locked        :1;    /* The volume is locked */
    unsigned    prevent        :1;    /* The device defaults in the prevent state after power up */    
    unsigned    eject        :1;    /* The device can eject the volume */
    __u8        disconnect    :1;    /* The device can break request > ctl */    
    __u8        reserved6_5    :1;
    unsigned    ecc        :1;    /* Supports error correction */
    unsigned    cmprs        :1;    /* Supports data compression */
    unsigned    reserved7_0    :1;
    unsigned    blk512        :1;    /* Supports 512 bytes block size */
    unsigned    blk1024        :1;    /* Supports 1024 bytes block size */
    unsigned    reserved7_3_6    :4;
    unsigned    blk32768    :1;    /* slowb - the device restricts the byte count for PIO */
                        /* transfers for slow buffer memory ??? */
                        /* Also 32768 block size in some cases */
    __u16        max_speed;        /* Maximum speed supported in KBps */
    __u8        reserved10, reserved11;
    __u16        ctl;            /* Continuous Transfer Limit in blocks */
    __u16        speed;            /* Current Speed, in KBps */
    __u16        buffer_size;        /* Buffer Size, in 512 bytes */
    __u8        reserved18, reserved19;
} idetape_capabilities_page_t;

/*
 *    Block Size Page
 */
typedef struct {
    unsigned    page_code    :6;    /* Page code - Should be 0x30 */
    unsigned    reserved1_6    :1;
    unsigned    ps        :1;
    __u8        page_length;        /* Page Length - Should be 2 */
    __u8        reserved2;
    unsigned    play32        :1;
    unsigned    play32_5    :1;
    unsigned    reserved2_23    :2;
    unsigned    record32    :1;
    unsigned    record32_5    :1;
    unsigned    reserved2_6    :1;
    unsigned    one        :1;
} idetape_block_size_page_t;

/*
 *    A pipeline stage.
 */
typedef struct idetape_stage_s {
    struct request rq;            /* The corresponding request */
    struct buffer_head *bh;            /* The data buffers */
    struct idetape_stage_s *next;        /* Pointer to the next stage */
    os_aux_t *aux;                /* OnStream aux ptr */
} idetape_stage_t;

/*
 *    REQUEST SENSE packet command result - Data Format.
 */
typedef struct {
    unsigned    error_code    :7;    /* Current of deferred errors */
    unsigned    valid        :1;    /* The information field conforms to QIC-157C */
    __u8        reserved1    :8;    /* Segment Number - Reserved */
    unsigned    sense_key    :4;    /* Sense Key */
    unsigned    reserved2_4    :1;    /* Reserved */
    unsigned    ili        :1;    /* Incorrect Length Indicator */
    unsigned    eom        :1;    /* End Of Medium */
    unsigned    filemark     :1;    /* Filemark */
    __u32        information __attribute__ ((packed));
    __u8        asl;            /* Additional sense length (n-7) */
    __u32        command_specific;    /* Additional command specific information */
    __u8        asc;            /* Additional Sense Code */
    __u8        ascq;            /* Additional Sense Code Qualifier */
    __u8        replaceable_unit_code;    /* Field Replaceable Unit Code */
    unsigned    sk_specific1     :7;    /* Sense Key Specific */
    unsigned    sksv        :1;    /* Sense Key Specific information is valid */
    __u8        sk_specific2;        /* Sense Key Specific */
    __u8        sk_specific3;        /* Sense Key Specific */
    __u8        pad[2];            /* Padding to 20 bytes */
} idetape_request_sense_result_t;


/*
 *    Most of our global data which we need to save even as we leave the
 *    driver due to an interrupt or a timer event is stored in a variable
 *    of type idetape_tape_t, defined below.
 */
typedef struct {
    ide_drive_t *drive;
    devfs_handle_t de_r, de_n;

    /*
     *    Since a typical character device operation requires more
     *    than one packet command, we provide here enough memory
     *    for the maximum of interconnected packet commands.
     *    The packet commands are stored in the circular array pc_stack.
     *    pc_stack_index points to the last used entry, and warps around
     *    to the start when we get to the last array entry.
     *
     *    pc points to the current processed packet command.
     *
     *    failed_pc points to the last failed packet command, or contains
     *    NULL if we do not need to retry any packet command. This is
     *    required since an additional packet command is needed before the
     *    retry, to get detailed information on what went wrong.
     */
    idetape_pc_t *pc;            /* Current packet command */
    idetape_pc_t *failed_pc;         /* Last failed packet command */
    idetape_pc_t pc_stack[IDETAPE_PC_STACK];/* Packet command stack */
    int pc_stack_index;            /* Next free packet command storage space */
    struct request rq_stack[IDETAPE_PC_STACK];
    int rq_stack_index;            /* We implement a circular array */

    /*
     *    DSC polling variables.
     *
     *    While polling for DSC we use postponed_rq to postpone the
     *    current request so that ide.c will be able to service
     *    pending requests on the other device. Note that at most
     *    we will have only one DSC (usually data transfer) request
     *    in the device request queue. Additional requests can be
     *    queued in our internal pipeline, but they will be visible
     *    to ide.c only one at a time.
     */
    struct request *postponed_rq;
    unsigned long dsc_polling_start;    /* The time in which we started polling for DSC */
    struct timer_list dsc_timer;        /* Timer used to poll for dsc */
    unsigned long best_dsc_rw_frequency;    /* Read/Write dsc polling frequency */
    unsigned long dsc_polling_frequency;    /* The current polling frequency */
    unsigned long dsc_timeout;        /* Maximum waiting time */

    /*
     *    Read position information
     */
    byte partition;
    unsigned int first_frame_position;        /* Current block */
    unsigned int last_frame_position;
    unsigned int blocks_in_buffer;

    /*
     *    Last error information
     */
    byte sense_key, asc, ascq;

    /*
     *    Character device operation
     */
    unsigned int minor;
    char name[4];                    /* device name */
    idetape_chrdev_direction_t chrdev_direction;    /* Current character device data transfer direction */

    /*
     *    Device information
     */
    unsigned short tape_block_size;            /* Usually 512 or 1024 bytes */
    int user_bs_factor;
    idetape_capabilities_page_t capabilities;    /* Copy of the tape's Capabilities and Mechanical Page */

    /*
     *    Active data transfer request parameters.
     *
     *    At most, there is only one ide-tape originated data transfer
     *    request in the device request queue. This allows ide.c to
     *    easily service requests from the other device when we
     *    postpone our active request. In the pipelined operation
     *    mode, we use our internal pipeline structure to hold
     *    more data requests.
     *
     *    The data buffer size is chosen based on the tape's
     *    recommendation.
     */
    struct request *active_data_request;    /* Pointer to the request which is waiting in the device request queue */
    int stage_size;                /* Data buffer size (chosen based on the tape's recommendation */
    idetape_stage_t *merge_stage;
    int merge_stage_size;
    struct buffer_head *bh;
    char *b_data;
    int b_count;
    
    /*
     *    Pipeline parameters.
     *
     *    To accomplish non-pipelined mode, we simply set the following
     *    variables to zero (or NULL, where appropriate).
     */
    int nr_stages;                /* Number of currently used stages */
    int nr_pending_stages;            /* Number of pending stages */
    int max_stages, min_pipeline, max_pipeline; /* We will not allocate more than this number of stages */
    idetape_stage_t *first_stage;        /* The first stage which will be removed from the pipeline */
    idetape_stage_t *active_stage;        /* The currently active stage */
    idetape_stage_t *next_stage;        /* Will be serviced after the currently active request */
    idetape_stage_t *last_stage;        /* New requests will be added to the pipeline here */
    idetape_stage_t *cache_stage;        /* Optional free stage which we can use */
    int pages_per_stage;
    int excess_bh_size;            /* Wasted space in each stage */

    unsigned long flags;            /* Status/Action flags: long for set_bit */
    spinlock_t spinlock;            /* protects the ide-tape queue */

    /*
     * Measures average tape speed
     */
    unsigned long avg_time;
    int avg_size;
    int avg_speed;

    idetape_request_sense_result_t sense;    /* last sense information */

    char vendor_id[10];
    char product_id[18];
    char firmware_revision[6];
    int firmware_revision_num;

    int door_locked;            /* the door is currently locked */

    /*
     * OnStream flags
     */
    int onstream;                /* the tape is an OnStream tape */
    int raw;                /* OnStream raw access (32.5KB block size) */
    int cur_frames;                /* current number of frames in internal buffer */
    int max_frames;                /* max number of frames in internal buffer */
    int logical_blk_num;            /* logical block number */
    __u16 wrt_pass_cntr;            /* write pass counter */
    __u32 update_frame_cntr;        /* update frame counter */
    struct completion *waiting;
    int onstream_write_error;        /* write error recovery active */
    int header_ok;                /* header frame verified ok */
    int linux_media;            /* reading linux-specifc media */
    int linux_media_version;
    char application_sig[5];        /* application signature */
    int filemark_cnt;
    int first_mark_addr;
    int last_mark_addr;
    int eod_frame_addr;
    unsigned long cmd_start_time;
    unsigned long max_cmd_time;
    unsigned capacity;

    /*
     * Optimize the number of "buffer filling"
     * mode sense commands.
     */
    unsigned long last_buffer_fill;        /* last time in which we issued fill cmd */
    int req_buffer_fill;            /* buffer fill command requested */
    int writes_since_buffer_fill;
    int reads_since_buffer_fill;

    /*
     * Limit the number of times a request can
     * be postponed, to avoid an infinite postpone
     * deadlock.
     */
    int postpone_cnt;            /* request postpone count limit */

    /*
     * Measures number of frames:
     *
     * 1. written/read to/from the driver pipeline (pipeline_head).
     * 2. written/read to/from the tape buffers (buffer_head).
     * 3. written/read by the tape to/from the media (tape_head).
     */
    int pipeline_head;
    int buffer_head;
    int tape_head;
    int last_tape_head;

    /*
     * Speed control at the tape buffers input/output
     */
    unsigned long insert_time;
    int insert_size;
    int insert_speed;
    int max_insert_speed;
    int measure_insert_time;

    /*
     * Measure tape still time, in milliseconds
     */
    unsigned long tape_still_time_begin;
    int tape_still_time;

    /*
     * Speed regulation negative feedback loop
     */
    int speed_control;
    int pipeline_head_speed, controlled_pipeline_head_speed, uncontrolled_pipeline_head_speed;
    int controlled_last_pipeline_head, uncontrolled_last_pipeline_head;
    unsigned long uncontrolled_pipeline_head_time, controlled_pipeline_head_time;
    int controlled_previous_pipeline_head, uncontrolled_previous_pipeline_head;
    unsigned long controlled_previous_head_time, uncontrolled_previous_head_time;
    int restart_speed_control_req;

        /*
         * Debug_level determines amount of debugging output;
         * can be changed using /proc/ide/hdx/settings
         * 0 : almost no debugging output
         * 1 : 0+output errors only
         * 2 : 1+output all sensekey/asc
         * 3 : 2+follow all chrdev related procedures
         * 4 : 3+follow all procedures
         * 5 : 4+include pc_stack rq_stack info
         * 6 : 5+USE_COUNT updates
         */
         int debug_level; 
} idetape_tape_t;

/*
 *    Tape door status
 */
#define DOOR_UNLOCKED            0
#define DOOR_LOCKED            1
#define DOOR_EXPLICITLY_LOCKED        2

/*
 *    Tape flag bits values.
 */
#define IDETAPE_IGNORE_DSC        0
#define IDETAPE_ADDRESS_VALID        1    /* 0 When the tape position is unknown */
#define IDETAPE_BUSY            2    /* Device already opened */
#define IDETAPE_PIPELINE_ERROR        3    /* Error detected in a pipeline stage */
#define IDETAPE_DETECT_BS        4    /* Attempt to auto-detect the current user block size */
#define IDETAPE_FILEMARK        5    /* Currently on a filemark */
#define IDETAPE_DRQ_INTERRUPT        6    /* DRQ interrupt device */
#define IDETAPE_READ_ERROR        7
#define IDETAPE_PIPELINE_ACTIVE        8    /* pipeline active */

/*
 *    Supported ATAPI tape drives packet commands
 */
#define IDETAPE_TEST_UNIT_READY_CMD    0x00
#define IDETAPE_REWIND_CMD        0x01
#define IDETAPE_REQUEST_SENSE_CMD    0x03
#define IDETAPE_READ_CMD        0x08
#define IDETAPE_WRITE_CMD        0x0a
#define IDETAPE_WRITE_FILEMARK_CMD    0x10
#define IDETAPE_SPACE_CMD        0x11
#define IDETAPE_INQUIRY_CMD        0x12
#define IDETAPE_ERASE_CMD        0x19
#define IDETAPE_MODE_SENSE_CMD        0x1a
#define IDETAPE_MODE_SELECT_CMD        0x15
#define IDETAPE_LOAD_UNLOAD_CMD        0x1b
#define IDETAPE_PREVENT_CMD        0x1e
#define IDETAPE_LOCATE_CMD        0x2b
#define IDETAPE_READ_POSITION_CMD    0x34
#define IDETAPE_READ_BUFFER_CMD        0x3c
#define IDETAPE_SET_SPEED_CMD        0xbb

/*
 *    Some defines for the READ BUFFER command
 */
#define IDETAPE_RETRIEVE_FAULTY_BLOCK    6

/*
 *    Some defines for the SPACE command
 */
#define IDETAPE_SPACE_OVER_FILEMARK    1
#define IDETAPE_SPACE_TO_EOD        3

/*
 *    Some defines for the LOAD UNLOAD command
 */
#define IDETAPE_LU_LOAD_MASK        1
#define IDETAPE_LU_RETENSION_MASK    2
#define IDETAPE_LU_EOT_MASK        4

/*
 *    Special requests for our block device strategy routine.
 *
 *    In order to service a character device command, we add special
 *    requests to the tail of our block device request queue and wait
 *    for their completion.
 *
 */
#define IDETAPE_FIRST_RQ        90

/*
 *     IDETAPE_PC_RQ is used to queue a packet command in the request queue.
 */
#define IDETAPE_PC_RQ1            90
#define IDETAPE_PC_RQ2            91

/*
 *    IDETAPE_READ_RQ and IDETAPE_WRITE_RQ are used by our
 *    character device interface to request read/write operations from
 *    our block device interface.
 */
#define IDETAPE_READ_RQ            92
#define IDETAPE_WRITE_RQ        93
#define IDETAPE_ABORTED_WRITE_RQ    94
#define IDETAPE_ABORTED_READ_RQ        95
#define IDETAPE_READ_BUFFER_RQ        96

#define IDETAPE_LAST_RQ            96

/*
 *    A macro which can be used to check if a we support a given
 *    request command.
 */
#define IDETAPE_RQ_CMD(cmd)         ((cmd >= IDETAPE_FIRST_RQ) && (cmd <= IDETAPE_LAST_RQ))

/*
 *    Error codes which are returned in rq->errors to the higher part
 *    of the driver.
 */
#define    IDETAPE_ERROR_GENERAL        101
#define    IDETAPE_ERROR_FILEMARK        102
#define    IDETAPE_ERROR_EOD        103

/*
 *    The ATAPI Status Register.
 */
typedef union {
    unsigned all            :8;
    struct {
        unsigned check        :1;    /* Error occurred */
        unsigned idx        :1;    /* Reserved */
        unsigned corr        :1;    /* Correctable error occurred */
        unsigned drq        :1;    /* Data is request by the device */
        unsigned dsc        :1;    /* Buffer availability / Media access command finished */
        unsigned reserved5    :1;    /* Reserved */
        unsigned drdy        :1;    /* Ignored for ATAPI commands (ready to accept ATA command) */
        unsigned bsy        :1;    /* The device has access to the command block */
    } b;
} idetape_status_reg_t;

/*
 *    The ATAPI error register.
 */
typedef union {
    unsigned all            :8;
    struct {
        unsigned ili        :1;    /* Illegal Length Indication */
        unsigned eom        :1;    /* End Of Media Detected */
        unsigned abrt        :1;    /* Aborted command - As defined by ATA */
        unsigned mcr        :1;    /* Media Change Requested - As defined by ATA */
        unsigned sense_key    :4;    /* Sense key of the last failed packet command */
    } b;
} idetape_error_reg_t;

/*
 *    ATAPI Feature Register
 */
typedef union {
    unsigned all            :8;
    struct {
        unsigned dma        :1;    /* Using DMA or PIO */
        unsigned reserved321    :3;    /* Reserved */
        unsigned reserved654    :3;    /* Reserved (Tag Type) */
        unsigned reserved7    :1;    /* Reserved */
    } b;
} idetape_feature_reg_t;

/*
 *    ATAPI Byte Count Register.
 */
typedef union {
    unsigned all            :16;
    struct {
        unsigned low        :8;    /* LSB */
        unsigned high        :8;    /* MSB */
    } b;
} idetape_bcount_reg_t;

/*
 *    ATAPI Interrupt Reason Register.
 */
typedef union {
    unsigned all            :8;
    struct {
        unsigned cod        :1;    /* Information transferred is command (1) or data (0) */
        unsigned io        :1;    /* The device requests us to read (1) or write (0) */
        unsigned reserved    :6;    /* Reserved */
    } b;
} idetape_ireason_reg_t;

/*
 *    ATAPI Drive Select Register
 */
typedef union {    
    unsigned all            :8;
    struct {
        unsigned sam_lun    :4;    /* Should be zero with ATAPI (not used) */
        unsigned drv        :1;    /* The responding drive will be drive 0 (0) or drive 1 (1) */
        unsigned one5        :1;    /* Should be set to 1 */
        unsigned reserved6    :1;    /* Reserved */
        unsigned one7        :1;    /* Should be set to 1 */
    } b;
} idetape_drivesel_reg_t;

/*
 *    ATAPI Device Control Register
 */
typedef union {            
    unsigned all            :8;
    struct {
        unsigned zero0        :1;    /* Should be set to zero */
        unsigned nien        :1;    /* Device interrupt is disabled (1) or enabled (0) */
        unsigned srst        :1;    /* ATA software reset. ATAPI devices should use the new ATAPI srst. */
        unsigned one3        :1;    /* Should be set to 1 */
        unsigned reserved4567    :4;    /* Reserved */
    } b;
} idetape_control_reg_t;

/*
 *    idetape_chrdev_t provides the link between out character device
 *    interface and our block device interface and the corresponding
 *    ide_drive_t structure.
 */
typedef struct {
    ide_drive_t *drive;
} idetape_chrdev_t;

/*
 *    The following is used to format the general configuration word of
 *    the ATAPI IDENTIFY DEVICE command.
 */
struct idetape_id_gcw {    
    unsigned packet_size        :2;    /* Packet Size */
    unsigned reserved234        :3;    /* Reserved */
    unsigned drq_type        :2;    /* Command packet DRQ type */
    unsigned removable        :1;    /* Removable media */
    unsigned device_type        :5;    /* Device type */
    unsigned reserved13        :1;    /* Reserved */
    unsigned protocol        :2;    /* Protocol type */
};

/*
 *    INQUIRY packet command - Data Format (From Table 6-8 of QIC-157C)
 */
typedef struct {
    unsigned    device_type    :5;    /* Peripheral Device Type */
    unsigned    reserved0_765    :3;    /* Peripheral Qualifier - Reserved */
    unsigned    reserved1_6t0    :7;    /* Reserved */
    unsigned    rmb        :1;    /* Removable Medium Bit */
    unsigned    ansi_version    :3;    /* ANSI Version */
    unsigned    ecma_version    :3;    /* ECMA Version */
    unsigned    iso_version    :2;    /* ISO Version */
    unsigned    response_format :4;    /* Response Data Format */
    unsigned    reserved3_45    :2;    /* Reserved */
    unsigned    reserved3_6    :1;    /* TrmIOP - Reserved */
    unsigned    reserved3_7    :1;    /* AENC - Reserved */
    __u8        additional_length;    /* Additional Length (total_length-4) */
    __u8        rsv5, rsv6, rsv7;    /* Reserved */
    __u8        vendor_id[8];        /* Vendor Identification */
    __u8        product_id[16];        /* Product Identification */
    __u8        revision_level[4];    /* Revision Level */
    __u8        vendor_specific[20];    /* Vendor Specific - Optional */
    __u8        reserved56t95[40];    /* Reserved - Optional */
                        /* Additional information may be returned */
} idetape_inquiry_result_t;

/*
 *    READ POSITION packet command - Data Format (From Table 6-57)
 */
typedef struct {
    unsigned    reserved0_10    :2;    /* Reserved */
    unsigned    bpu        :1;    /* Block Position Unknown */    
    unsigned    reserved0_543    :3;    /* Reserved */
    unsigned    eop        :1;    /* End Of Partition */
    unsigned    bop        :1;    /* Beginning Of Partition */
    u8        partition;        /* Partition Number */
    u8        reserved2, reserved3;    /* Reserved */
    u32        first_block;        /* First Block Location */
    u32        last_block;        /* Last Block Location (Optional) */
    u8        reserved12;        /* Reserved */
    u8        blocks_in_buffer[3];    /* Blocks In Buffer - (Optional) */
    u32        bytes_in_buffer;    /* Bytes In Buffer (Optional) */
} idetape_read_position_result_t;

/*
 *    Follows structures which are related to the SELECT SENSE / MODE SENSE
 *    packet commands. Those packet commands are still not supported
 *    by ide-tape.
 */
#define IDETAPE_BLOCK_DESCRIPTOR    0
#define    IDETAPE_CAPABILITIES_PAGE    0x2a
#define IDETAPE_PARAMTR_PAGE        0x2b   /* Onstream DI-x0 only */
#define IDETAPE_BLOCK_SIZE_PAGE        0x30
#define IDETAPE_BUFFER_FILLING_PAGE    0x33

/*
 *    Mode Parameter Header for the MODE SENSE packet command
 */
typedef struct {
    __u8    mode_data_length;    /* Length of the following data transfer */
    __u8    medium_type;        /* Medium Type */
    __u8    dsp;            /* Device Specific Parameter */
    __u8    bdl;            /* Block Descriptor Length */
#if 0
    /* data transfer page */
    __u8    page_code    :6;
    __u8    reserved0_6    :1;
    __u8    ps        :1;    /* parameters saveable */
    __u8    page_length;        /* page Length == 0x02 */
    __u8    reserved2;
    __u8    read32k        :1;    /* 32k blk size (data only) */
    __u8    read32k5    :1;    /* 32.5k blk size (data&AUX) */
    __u8    reserved3_23    :2;
    __u8    write32k    :1;    /* 32k blk size (data only) */
    __u8    write32k5    :1;    /* 32.5k blk size (data&AUX) */
    __u8    reserved3_6    :1;
    __u8    streaming    :1;    /* streaming mode enable */
#endif
} idetape_mode_parameter_header_t;

/*
 *    Mode Parameter Block Descriptor the MODE SENSE packet command
 *
 *    Support for block descriptors is optional.
 */
typedef struct {
    __u8        density_code;        /* Medium density code */
    __u8        blocks[3];        /* Number of blocks */
    __u8        reserved4;        /* Reserved */
    __u8        length[3];        /* Block Length */
} idetape_parameter_block_descriptor_t;

/*
 *    The Data Compression Page, as returned by the MODE SENSE packet command.
 */
typedef struct {
    unsigned    page_code    :6;    /* Page Code - Should be 0xf */
    unsigned    reserved0    :1;    /* Reserved */
    unsigned    ps        :1;
    __u8        page_length;        /* Page Length - Should be 14 */
    unsigned    reserved2    :6;    /* Reserved */
    unsigned    dcc        :1;    /* Data Compression Capable */
    unsigned    dce        :1;    /* Data Compression Enable */
    unsigned    reserved3    :5;    /* Reserved */
    unsigned    red        :2;    /* Report Exception on Decompression */
    unsigned    dde        :1;    /* Data Decompression Enable */
    __u32        ca;            /* Compression Algorithm */
    __u32        da;            /* Decompression Algorithm */
    __u8        reserved[4];        /* Reserved */
} idetape_data_compression_page_t;

/*
 *    The Medium Partition Page, as returned by the MODE SENSE packet command.
 */
typedef struct {
    unsigned    page_code    :6;    /* Page Code - Should be 0x11 */
    unsigned    reserved1_6    :1;    /* Reserved */
    unsigned    ps        :1;
    __u8        page_length;        /* Page Length - Should be 6 */
    __u8        map;            /* Maximum Additional Partitions - Should be 0 */
    __u8        apd;            /* Additional Partitions Defined - Should be 0 */
    unsigned    reserved4_012    :3;    /* Reserved */
    unsigned    psum        :2;    /* Should be 0 */
    unsigned    idp        :1;    /* Should be 0 */
    unsigned    sdp        :1;    /* Should be 0 */
    unsigned    fdp        :1;    /* Fixed Data Partitions */
    __u8        mfr;            /* Medium Format Recognition */
    __u8        reserved[2];        /* Reserved */
} idetape_medium_partition_page_t;

/*
 *    Run time configurable parameters.
 */
typedef struct {
    int    dsc_rw_frequency;
    int    dsc_media_access_frequency;
    int    nr_stages;
} idetape_config_t;

/*
 *    The variables below are used for the character device interface.
 *    Additional state variables are defined in our ide_drive_t structure.
 */
static idetape_chrdev_t idetape_chrdevs[MAX_HWIFS * MAX_DRIVES];
static int idetape_chrdev_present = 0;

#if IDETAPE_DEBUG_LOG_VERBOSE

/*
 * DO NOT REMOVE, BUILDING A VERBOSE DEBUG SCHEME FOR ATAPI
 */

char *idetape_sense_key_verbose (byte idetape_sense_key)
{
    switch (idetape_sense_key) {
        default: {
            char buf[22];
            sprintf(buf, "IDETAPE_SENSE (0x%02x)", idetape_sense_key);
            return(buf);
        }

    }
}

char *idetape_command_key_verbose (byte idetape_command_key)
{
    switch (idetape_command_key) {
        case IDETAPE_TEST_UNIT_READY_CMD:    return("TEST_UNIT_READY_CMD");
        case IDETAPE_REWIND_CMD:        return("REWIND_CMD");
        case IDETAPE_REQUEST_SENSE_CMD:        return("REQUEST_SENSE_CMD");
        case IDETAPE_READ_CMD:            return("READ_CMD");
        case IDETAPE_WRITE_CMD:            return("WRITE_CMD");
        case IDETAPE_WRITE_FILEMARK_CMD:    return("WRITE_FILEMARK_CMD");
        case IDETAPE_SPACE_CMD:            return("SPACE_CMD");
        case IDETAPE_INQUIRY_CMD:        return("INQUIRY_CMD");
        case IDETAPE_ERASE_CMD:            return("ERASE_CMD");
        case IDETAPE_MODE_SENSE_CMD:        return("MODE_SENSE_CMD");
        case IDETAPE_MODE_SELECT_CMD:        return("MODE_SELECT_CMD");
        case IDETAPE_LOAD_UNLOAD_CMD:        return("LOAD_UNLOAD_CMD");
        case IDETAPE_PREVENT_CMD:        return("PREVENT_CMD");
        case IDETAPE_LOCATE_CMD:        return("LOCATE_CMD");
        case IDETAPE_READ_POSITION_CMD:        return("READ_POSITION_CMD");
        case IDETAPE_READ_BUFFER_CMD:        return("READ_BUFFER_CMD");
        case IDETAPE_SET_SPEED_CMD:        return("SET_SPEED_CMD");
        default: {
                char buf[20];
                sprintf(buf, "CMD (0x%02x)", idetape_command_key);
                return(buf);
            }
    }
}
#endif /* IDETAPE_DEBUG_LOG_VERBOSE */

/*
 *      Function declarations
 *
 */
static void idetape_onstream_mode_sense_tape_parameter_page(ide_drive_t *drive, int debug);
static int idetape_chrdev_release (struct inode *inode, struct file *filp);
static void idetape_write_release (struct inode *inode);

/*
 *    Too bad. The drive wants to send us data which we are not ready to accept.
 *    Just throw it away.
 */
static void idetape_discard_data (ide_drive_t *drive, unsigned int bcount)
{
    while (bcount--)
        IN_BYTE (IDE_DATA_REG);
}

static void idetape_input_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
{
    struct buffer_head *bh = pc->bh;
    int count;

    while (bcount) {
#if IDETAPE_DEBUG_BUGS
        if (bh == NULL) {
            printk (KERN_ERR "ide-tape: bh == NULL in idetape_input_buffers\n");
            idetape_discard_data (drive, bcount);
            return;
        }
#endif /* IDETAPE_DEBUG_BUGS */
        count = IDE_MIN (bh->b_size - atomic_read(&bh->b_count), bcount);
        atapi_input_bytes (drive, bh->b_data + atomic_read(&bh->b_count), count);
        bcount -= count;
        atomic_add(count, &bh->b_count);
        if (atomic_read(&bh->b_count) == bh->b_size) {
            bh = bh->b_reqnext;
            if (bh)
                atomic_set(&bh->b_count, 0);
        }
    }
    pc->bh = bh;
}

static void idetape_output_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
{
    struct buffer_head *bh = pc->bh;
    int count;

    while (bcount) {
#if IDETAPE_DEBUG_BUGS
        if (bh == NULL) {
            printk (KERN_ERR "ide-tape: bh == NULL in idetape_output_buffers\n");
            return;
        }
#endif /* IDETAPE_DEBUG_BUGS */
        count = IDE_MIN (pc->b_count, bcount);
        atapi_output_bytes (drive, pc->b_data, count);
        bcount -= count;
        pc->b_data += count;
        pc->b_count -= count;
        if (!pc->b_count) {
            pc->bh = bh = bh->b_reqnext;
            if (bh) {
                pc->b_data = bh->b_data;
                pc->b_count = atomic_read(&bh->b_count);
            }
        }
    }
}

#ifdef CONFIG_BLK_DEV_IDEDMA
static void idetape_update_buffers (idetape_pc_t *pc)
{
    struct buffer_head *bh = pc->bh;
    int count, bcount = pc->actually_transferred;

    if (test_bit (PC_WRITING, &pc->flags))
        return;
    while (bcount) {
#if IDETAPE_DEBUG_BUGS
        if (bh == NULL) {
            printk (KERN_ERR "ide-tape: bh == NULL in idetape_update_buffers\n");
            return;
        }
#endif /* IDETAPE_DEBUG_BUGS */
        count = IDE_MIN (bh->b_size, bcount);
        atomic_set(&bh->b_count, count);
        if (atomic_read(&bh->b_count) == bh->b_size)
            bh = bh->b_reqnext;
        bcount -= count;
    }
    pc->bh = bh;
}
#endif /* CONFIG_BLK_DEV_IDEDMA */

/*
 *    idetape_next_pc_storage returns a pointer to a place in which we can
 *    safely store a packet command, even though we intend to leave the
 *    driver. A storage space for a maximum of IDETAPE_PC_STACK packet
 *    commands is allocated at initialization time.
 */
static idetape_pc_t *idetape_next_pc_storage (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 5)
        printk (KERN_INFO "ide-tape: pc_stack_index=%d\n",tape->pc_stack_index);
#endif /* IDETAPE_DEBUG_LOG */
    if (tape->pc_stack_index==IDETAPE_PC_STACK)
        tape->pc_stack_index=0;
    return (&tape->pc_stack[tape->pc_stack_index++]);
}

/*
 *    idetape_next_rq_storage is used along with idetape_next_pc_storage.
 *    Since we queue packet commands in the request queue, we need to
 *    allocate a request, along with the allocation of a packet command.
 */
 
/**************************************************************
 *                                                            *
 *  This should get fixed to use kmalloc(.., GFP_ATOMIC)      *
 *  followed later on by kfree().   -ml                       *
 *                                                            *
 **************************************************************/
 
static struct request *idetape_next_rq_storage (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 5)
        printk (KERN_INFO "ide-tape: rq_stack_index=%d\n",tape->rq_stack_index);
#endif /* IDETAPE_DEBUG_LOG */
    if (tape->rq_stack_index==IDETAPE_PC_STACK)
        tape->rq_stack_index=0;
    return (&tape->rq_stack[tape->rq_stack_index++]);
}

/*
 *    idetape_init_pc initializes a packet command.
 */
static void idetape_init_pc (idetape_pc_t *pc)
{
    memset (pc->c, 0, 12);
    pc->retries = 0;
    pc->flags = 0;
    pc->request_transfer = 0;
    pc->buffer = pc->pc_buffer;
    pc->buffer_size = IDETAPE_PC_BUFFER_SIZE;
    pc->bh = NULL;
    pc->b_data = NULL;
}

/*
 *    idetape_analyze_error is called on each failed packet command retry
 *    to analyze the request sense. We currently do not utilize this
 *    information.
 */
static void idetape_analyze_error (ide_drive_t *drive, idetape_request_sense_result_t *result)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t *pc = tape->failed_pc;

    tape->sense     = *result;
    tape->sense_key = result->sense_key;
    tape->asc       = result->asc;
    tape->ascq      = result->ascq;
#if IDETAPE_DEBUG_LOG
    /*
     *    Without debugging, we only log an error if we decided to
     *    give up retrying.
     */
    if (tape->debug_level >= 1)
        printk (KERN_INFO "ide-tape: pc = %x, sense key = %x, asc = %x, ascq = %x\n",
                pc->c[0], result->sense_key, result->asc, result->ascq);
#if IDETAPE_DEBUG_LOG_VERBOSE
    if (tape->debug_level >= 1)
        printk (KERN_INFO "ide-tape: pc = %s, sense key = %x, asc = %x, ascq = %x\n",
            idetape_command_key_verbose((byte) pc->c[0]),
            result->sense_key,
            result->asc,
            result->ascq);
#endif /* IDETAPE_DEBUG_LOG_VERBOSE */
#endif /* IDETAPE_DEBUG_LOG */

    if (tape->onstream && result->sense_key == 2 && result->asc == 0x53 && result->ascq == 2) {
        clear_bit(PC_DMA_ERROR, &pc->flags);
        ide_stall_queue(drive, HZ / 2);
        return;
    }
#ifdef CONFIG_BLK_DEV_IDEDMA

    /*
     *    Correct pc->actually_transferred by asking the tape.
     */
    if (test_bit (PC_DMA_ERROR, &pc->flags)) {
        pc->actually_transferred = pc->request_transfer - tape->tape_block_size * ntohl (get_unaligned (&result->information));
        idetape_update_buffers (pc);
    }
#endif /* CONFIG_BLK_DEV_IDEDMA */
    if (pc->c[0] == IDETAPE_READ_CMD && result->filemark) {
        pc->error = IDETAPE_ERROR_FILEMARK;
        set_bit (PC_ABORT, &pc->flags);
    }
    if (pc->c[0] == IDETAPE_WRITE_CMD) {
        if (result->eom || (result->sense_key == 0xd && result->asc == 0x0 && result->ascq == 0x2)) {
            pc->error = IDETAPE_ERROR_EOD;
            set_bit (PC_ABORT, &pc->flags);
        }
    }
    if (pc->c[0] == IDETAPE_READ_CMD || pc->c[0] == IDETAPE_WRITE_CMD) {
        if (result->sense_key == 8) {
            pc->error = IDETAPE_ERROR_EOD;
            set_bit (PC_ABORT, &pc->flags);
        }
        if (!test_bit (PC_ABORT, &pc->flags) && (tape->onstream || pc->actually_transferred))
            pc->retries = IDETAPE_MAX_PC_RETRIES + 1;
    }
}

static void idetape_abort_pipeline (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *stage = tape->next_stage;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk(KERN_INFO "ide-tape: %s: idetape_abort_pipeline called\n", tape->name);
#endif
    while (stage) {
        if (stage->rq.cmd == IDETAPE_WRITE_RQ)
            stage->rq.cmd = IDETAPE_ABORTED_WRITE_RQ;
        else if (stage->rq.cmd == IDETAPE_READ_RQ)
            stage->rq.cmd = IDETAPE_ABORTED_READ_RQ;
        stage = stage->next;
    }
}

/*
 *    idetape_active_next_stage will declare the next stage as "active".
 */
static void idetape_active_next_stage (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *stage = tape->next_stage;
    struct request *rq = &stage->rq;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_active_next_stage\n");
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
    if (stage == NULL) {
        printk (KERN_ERR "ide-tape: bug: Trying to activate a non existing stage\n");
        return;
    }
#endif /* IDETAPE_DEBUG_BUGS */    

    rq->buffer = NULL;
    rq->bh = stage->bh;
    tape->active_data_request = rq;
    tape->active_stage = stage;
    tape->next_stage = stage->next;
}

/*
 *    idetape_increase_max_pipeline_stages is a part of the feedback
 *    loop which tries to find the optimum number of stages. In the
 *    feedback loop, we are starting from a minimum maximum number of
 *    stages, and if we sense that the pipeline is empty, we try to
 *    increase it, until we reach the user compile time memory limit.
 */
static void idetape_increase_max_pipeline_stages (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    int increase = (tape->max_pipeline - tape->min_pipeline) / 10;
    
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_increase_max_pipeline_stages\n");
#endif /* IDETAPE_DEBUG_LOG */

    tape->max_stages += increase;
    tape->max_stages = IDE_MAX(tape->max_stages, tape->min_pipeline);
    tape->max_stages = IDE_MIN(tape->max_stages, tape->max_pipeline);
}

/*
 *    idetape_kfree_stage calls kfree to completely free a stage, along with
 *    its related buffers.
 */
static void __idetape_kfree_stage (idetape_stage_t *stage)
{
    struct buffer_head *prev_bh, *bh = stage->bh;
    int size;

    while (bh != NULL) {
        if (bh->b_data != NULL) {
            size = (int) bh->b_size;
            while (size > 0) {
                free_page ((unsigned long) bh->b_data);
                size -= PAGE_SIZE;
                bh->b_data += PAGE_SIZE;
            }
        }
        prev_bh = bh;
        bh = bh->b_reqnext;
        kfree (prev_bh);
    }
    kfree (stage);
}

static void idetape_kfree_stage (idetape_tape_t *tape, idetape_stage_t *stage)
{
    __idetape_kfree_stage (stage);
}

/*
 *    idetape_remove_stage_head removes tape->first_stage from the pipeline.
 *    The caller should avoid race conditions.
 */
static void idetape_remove_stage_head (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *stage;
    
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_remove_stage_head\n");
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
    if (tape->first_stage == NULL) {
        printk (KERN_ERR "ide-tape: bug: tape->first_stage is NULL\n");
        return;        
    }
    if (tape->active_stage == tape->first_stage) {
        printk (KERN_ERR "ide-tape: bug: Trying to free our active pipeline stage\n");
        return;
    }
#endif /* IDETAPE_DEBUG_BUGS */
    stage = tape->first_stage;
    tape->first_stage = stage->next;
    idetape_kfree_stage (tape, stage);
    tape->nr_stages--;
    if (tape->first_stage == NULL) {
        tape->last_stage = NULL;
#if IDETAPE_DEBUG_BUGS
        if (tape->next_stage != NULL)
            printk (KERN_ERR "ide-tape: bug: tape->next_stage != NULL\n");
        if (tape->nr_stages)
            printk (KERN_ERR "ide-tape: bug: nr_stages should be 0 now\n");
#endif /* IDETAPE_DEBUG_BUGS */
    }
}

/*
 *    idetape_end_request is used to finish servicing a request, and to
 *    insert a pending pipeline request into the main device queue.
 */
static void idetape_end_request (byte uptodate, ide_hwgroup_t *hwgroup)
{
    ide_drive_t *drive = hwgroup->drive;
    struct request *rq = hwgroup->rq;
    idetape_tape_t *tape = drive->driver_data;
    unsigned long flags;
    int error;
    int remove_stage = 0;
#if ONSTREAM_DEBUG
    idetape_stage_t *stage;
    os_aux_t *aux;
    unsigned char *p;
#endif

#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 4)
    printk (KERN_INFO "ide-tape: Reached idetape_end_request\n");
#endif /* IDETAPE_DEBUG_LOG */

    switch (uptodate) {
        case 0:    error = IDETAPE_ERROR_GENERAL; break;
        case 1: error = 0; break;
        default: error = uptodate;
    }
    rq->errors = error;
    if (error)
        tape->failed_pc = NULL;

    spin_lock_irqsave(&tape->spinlock, flags);
    if (tape->active_data_request == rq) {        /* The request was a pipelined data transfer request */
        tape->active_stage = NULL;
        tape->active_data_request = NULL;
        tape->nr_pending_stages--;
        if (rq->cmd == IDETAPE_WRITE_RQ) {
#if ONSTREAM_DEBUG
            if (tape->debug_level >= 2) {
                if (tape->onstream) {
                    stage = tape->first_stage;
                    aux = stage->aux;
                    p = stage->bh->b_data;
                    if (ntohl(aux->logical_blk_num) < 11300 && ntohl(aux->logical_blk_num) > 11100)
                        printk(KERN_INFO "ide-tape: finished writing logical blk %u (data %x %x %x %x)\n", ntohl(aux->logical_blk_num), *p++, *p++, *p++, *p++);
                }
            }
#endif
            if (tape->onstream && !tape->raw) {
                if (tape->first_frame_position == OS_DATA_ENDFRAME1) { 
#if ONSTREAM_DEBUG
                    if (tape->debug_level >= 2)
                        printk("ide-tape: %s: skipping over config parition..\n", tape->name);
#endif
                    tape->onstream_write_error = OS_PART_ERROR;
                    if (tape->waiting)
                        complete(tape->waiting);
                }
            }
            remove_stage = 1;
            if (error) {
                set_bit (IDETAPE_PIPELINE_ERROR, &tape->flags);
                if (error == IDETAPE_ERROR_EOD)
                    idetape_abort_pipeline (drive);
                if (tape->onstream && !tape->raw && error == IDETAPE_ERROR_GENERAL && tape->sense.sense_key == 3) {
                    clear_bit (IDETAPE_PIPELINE_ERROR, &tape->flags);
                    printk(KERN_ERR "ide-tape: %s: write error, enabling error recovery\n", tape->name);
                    tape->onstream_write_error = OS_WRITE_ERROR;
                    remove_stage = 0;
                    tape->nr_pending_stages++;
                    tape->next_stage = tape->first_stage;
                    rq->current_nr_sectors = rq->nr_sectors;
                    if (tape->waiting)
                        complete(tape->waiting);
                }
            }
        } else if (rq->cmd == IDETAPE_READ_RQ) {
            if (error == IDETAPE_ERROR_EOD) {
                set_bit (IDETAPE_PIPELINE_ERROR, &tape->flags);
                idetape_abort_pipeline(drive);
            }
        }
        if (tape->next_stage != NULL && !tape->onstream_write_error) {
            idetape_active_next_stage (drive);

            /*
             *    Insert the next request into the request queue.
             */
            (void) ide_do_drive_cmd (drive, tape->active_data_request, ide_end);
        } else if (!error) {
            if (!tape->onstream)
                idetape_increase_max_pipeline_stages (drive);
        }
    }
    ide_end_drive_cmd (drive, 0, 0);
    if (remove_stage)
        idetape_remove_stage_head (drive);
    if (tape->active_data_request == NULL)
        clear_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
    spin_unlock_irqrestore(&tape->spinlock, flags);
}

static ide_startstop_t idetape_request_sense_callback (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_request_sense_callback\n");
#endif /* IDETAPE_DEBUG_LOG */
    if (!tape->pc->error) {
        idetape_analyze_error (drive, (idetape_request_sense_result_t *) tape->pc->buffer);
        idetape_end_request (1, HWGROUP (drive));
    } else {
        printk (KERN_ERR "ide-tape: Error in REQUEST SENSE itself - Aborting request!\n");
        idetape_end_request (0, HWGROUP (drive));
    }
    return ide_stopped;
}

static void idetape_create_request_sense_cmd (idetape_pc_t *pc)
{
    idetape_init_pc (pc);    
    pc->c[0] = IDETAPE_REQUEST_SENSE_CMD;
    pc->c[4] = 20;
    pc->request_transfer = 18;
    pc->callback = &idetape_request_sense_callback;
}

/*
 *    idetape_queue_pc_head generates a new packet command request in front
 *    of the request queue, before the current request, so that it will be
 *    processed immediately, on the next pass through the driver.
 *
 *    idetape_queue_pc_head is called from the request handling part of
 *    the driver (the "bottom" part). Safe storage for the request should
 *    be allocated with idetape_next_pc_storage and idetape_next_rq_storage
 *    before calling idetape_queue_pc_head.
 *
 *    Memory for those requests is pre-allocated at initialization time, and
 *    is limited to IDETAPE_PC_STACK requests. We assume that we have enough
 *    space for the maximum possible number of inter-dependent packet commands.
 *
 *    The higher level of the driver - The ioctl handler and the character
 *    device handling functions should queue request to the lower level part
 *    and wait for their completion using idetape_queue_pc_tail or
 *    idetape_queue_rw_tail.
 */
static void idetape_queue_pc_head (ide_drive_t *drive,idetape_pc_t *pc,struct request *rq)
{
    ide_init_drive_cmd (rq);
    rq->buffer = (char *) pc;
    rq->cmd = IDETAPE_PC_RQ1;
    (void) ide_do_drive_cmd (drive, rq, ide_preempt);
}

/*
 *    idetape_retry_pc is called when an error was detected during the
 *    last packet command. We queue a request sense packet command in
 *    the head of the request list.
 */
static ide_startstop_t idetape_retry_pc (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t *pc;
    struct request *rq;
    idetape_error_reg_t error;

    error.all = IN_BYTE (IDE_ERROR_REG);
    pc = idetape_next_pc_storage (drive);
    rq = idetape_next_rq_storage (drive);
    idetape_create_request_sense_cmd (pc);
    set_bit (IDETAPE_IGNORE_DSC, &tape->flags);
    idetape_queue_pc_head (drive, pc, rq);
    return ide_stopped;
}

/*
 *    idetape_postpone_request postpones the current request so that
 *    ide.c will be able to service requests from another device on
 *    the same hwgroup while we are polling for DSC.
 */
static void idetape_postpone_request (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk(KERN_INFO "ide-tape: idetape_postpone_request\n");
#endif
    tape->postponed_rq = HWGROUP(drive)->rq;
    ide_stall_queue(drive, tape->dsc_polling_frequency);
}

/*
 *    idetape_pc_intr is the usual interrupt handler which will be called
 *    during a packet command. We will transfer some of the data (as
 *    requested by the drive) and will re-point interrupt handler to us.
 *    When data transfer is finished, we will act according to the
 *    algorithm described before idetape_issue_packet_command.
 *
 */
static ide_startstop_t idetape_pc_intr (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_status_reg_t status;
    idetape_bcount_reg_t bcount;
    idetape_ireason_reg_t ireason;
    idetape_pc_t *pc = tape->pc;

    unsigned int temp;
    unsigned long cmd_time;
#if SIMULATE_ERRORS
    static int error_sim_count = 0;
#endif

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_pc_intr interrupt handler\n");
#endif /* IDETAPE_DEBUG_LOG */    

    status.all = GET_STAT();                    /* Clear the interrupt */

#ifdef CONFIG_BLK_DEV_IDEDMA
    if (test_bit (PC_DMA_IN_PROGRESS, &pc->flags)) {
        if (HWIF(drive)->dmaproc(ide_dma_end, drive)) {
            /*
             * A DMA error is sometimes expected. For example,
             * if the tape is crossing a filemark during a
             * READ command, it will issue an irq and position
             * itself before the filemark, so that only a partial
             * data transfer will occur (which causes the DMA
             * error). In that case, we will later ask the tape
             * how much bytes of the original request were
             * actually transferred (we can't receive that
             * information from the DMA engine on most chipsets).
             */
            set_bit (PC_DMA_ERROR, &pc->flags);
        } else if (!status.b.check) {
            pc->actually_transferred = pc->request_transfer;
            idetape_update_buffers (pc);
        }
#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 4)
            printk (KERN_INFO "ide-tape: DMA finished\n");
#endif /* IDETAPE_DEBUG_LOG */
    }
#endif /* CONFIG_BLK_DEV_IDEDMA */

    if (!status.b.drq) {                        /* No more interrupts */
        cmd_time = (jiffies - tape->cmd_start_time) * 1000 / HZ;
        tape->max_cmd_time = IDE_MAX(cmd_time, tape->max_cmd_time);
#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 2)
            printk (KERN_INFO "ide-tape: Packet command completed, %d bytes transferred\n", pc->actually_transferred);
#endif /* IDETAPE_DEBUG_LOG */
        clear_bit (PC_DMA_IN_PROGRESS, &pc->flags);

        ide__sti();    /* local CPU only */

#if SIMULATE_ERRORS
        if ((pc->c[0] == IDETAPE_WRITE_CMD || pc->c[0] == IDETAPE_READ_CMD) && (++error_sim_count % 100) == 0) {
            printk(KERN_INFO "ide-tape: %s: simulating error\n", tape->name);
            status.b.check = 1;
        }
#endif
        if (status.b.check && pc->c[0] == IDETAPE_REQUEST_SENSE_CMD)
            status.b.check = 0;
        if (status.b.check || test_bit (PC_DMA_ERROR, &pc->flags)) {    /* Error detected */
#if IDETAPE_DEBUG_LOG
            if (tape->debug_level >= 1)
                printk (KERN_INFO "ide-tape: %s: I/O error, ",tape->name);
#endif /* IDETAPE_DEBUG_LOG */
            if (pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
                printk (KERN_ERR "ide-tape: I/O error in request sense command\n");
                return ide_do_reset (drive);
            }
#if IDETAPE_DEBUG_LOG
            if (tape->debug_level >= 1)
                printk(KERN_INFO "ide-tape: [cmd %x]: check condition\n", pc->c[0]);
#endif
            return idetape_retry_pc (drive);                /* Retry operation */
        }
        pc->error = 0;
        if (!tape->onstream && test_bit (PC_WAIT_FOR_DSC, &pc->flags) && !status.b.dsc) {    /* Media access command */
            tape->dsc_polling_start = jiffies;
            tape->dsc_polling_frequency = IDETAPE_DSC_MA_FAST;
            tape->dsc_timeout = jiffies + IDETAPE_DSC_MA_TIMEOUT;
            idetape_postpone_request (drive);        /* Allow ide.c to handle other requests */
            return ide_stopped;
        }
        if (tape->failed_pc == pc)
            tape->failed_pc = NULL;
        return pc->callback(drive);            /* Command finished - Call the callback function */
    }
#ifdef CONFIG_BLK_DEV_IDEDMA
    if (test_and_clear_bit (PC_DMA_IN_PROGRESS, &pc->flags)) {
        printk (KERN_ERR "ide-tape: The tape wants to issue more interrupts in DMA mode\n");
        printk (KERN_ERR "ide-tape: DMA disabled, reverting to PIO\n");
        (void) HWIF(drive)->dmaproc(ide_dma_off, drive);
        return ide_do_reset (drive);
    }
#endif /* CONFIG_BLK_DEV_IDEDMA */
    bcount.b.high = IN_BYTE (IDE_BCOUNTH_REG);            /* Get the number of bytes to transfer */
    bcount.b.low  = IN_BYTE (IDE_BCOUNTL_REG);            /* on this interrupt */
    ireason.all   = IN_BYTE (IDE_IREASON_REG);

    if (ireason.b.cod) {
        printk (KERN_ERR "ide-tape: CoD != 0 in idetape_pc_intr\n");
        return ide_do_reset (drive);
    }
    if (ireason.b.io == test_bit (PC_WRITING, &pc->flags)) {    /* Hopefully, we will never get here */
        printk (KERN_ERR "ide-tape: We wanted to %s, ", ireason.b.io ? "Write":"Read");
        printk (KERN_ERR "ide-tape: but the tape wants us to %s !\n",ireason.b.io ? "Read":"Write");
        return ide_do_reset (drive);
    }
    if (!test_bit (PC_WRITING, &pc->flags)) {            /* Reading - Check that we have enough space */
        temp = pc->actually_transferred + bcount.all;
        if ( temp > pc->request_transfer) {
            if (temp > pc->buffer_size) {
                printk (KERN_ERR "ide-tape: The tape wants to send us more data than expected - discarding data\n");
                idetape_discard_data (drive, bcount.all);
                ide_set_handler (drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
                return ide_started;
            }
#if IDETAPE_DEBUG_LOG
            if (tape->debug_level >= 2)
                printk (KERN_NOTICE "ide-tape: The tape wants to send us more data than expected - allowing transfer\n");
#endif /* IDETAPE_DEBUG_LOG */
        }
    }
    if (test_bit (PC_WRITING, &pc->flags)) {
        if (pc->bh != NULL)
            idetape_output_buffers (drive, pc, bcount.all);
        else
            atapi_output_bytes (drive,pc->current_position,bcount.all);    /* Write the current buffer */
    } else {
        if (pc->bh != NULL)
            idetape_input_buffers (drive, pc, bcount.all);
        else
            atapi_input_bytes (drive,pc->current_position,bcount.all);    /* Read the current buffer */
    }
    pc->actually_transferred += bcount.all;                    /* Update the current position */
    pc->current_position+=bcount.all;
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 2)
        printk(KERN_INFO "ide-tape: [cmd %x] transferred %d bytes on that interrupt\n", pc->c[0], bcount.all);
#endif
    ide_set_handler (drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);    /* And set the interrupt handler again */
    return ide_started;
}

/*
 *    Packet Command Interface
 *
 *    The current Packet Command is available in tape->pc, and will not
 *    change until we finish handling it. Each packet command is associated
 *    with a callback function that will be called when the command is
 *    finished.
 *
 *    The handling will be done in three stages:
 *
 *    1.    idetape_issue_packet_command will send the packet command to the
 *        drive, and will set the interrupt handler to idetape_pc_intr.
 *
 *    2.    On each interrupt, idetape_pc_intr will be called. This step
 *        will be repeated until the device signals us that no more
 *        interrupts will be issued.
 *
 *    3.    ATAPI Tape media access commands have immediate status with a
 *        delayed process. In case of a successful initiation of a
 *        media access packet command, the DSC bit will be set when the
 *        actual execution of the command is finished. 
 *        Since the tape drive will not issue an interrupt, we have to
 *        poll for this event. In this case, we define the request as
 *        "low priority request" by setting rq_status to
 *        IDETAPE_RQ_POSTPONED,     set a timer to poll for DSC and exit
 *        the driver.
 *
 *        ide.c will then give higher priority to requests which
 *        originate from the other device, until will change rq_status
 *        to RQ_ACTIVE.
 *
 *    4.    When the packet command is finished, it will be checked for errors.
 *
 *    5.    In case an error was found, we queue a request sense packet command
 *        in front of the request queue and retry the operation up to
 *        IDETAPE_MAX_PC_RETRIES times.
 *
 *    6.    In case no error was found, or we decided to give up and not
 *        to retry again, the callback function will be called and then
 *        we will handle the next request.
 *
 */
static ide_startstop_t idetape_transfer_pc(ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t *pc = tape->pc;
    idetape_ireason_reg_t ireason;
    int retries = 100;
    ide_startstop_t startstop;

    if (ide_wait_stat (&startstop,drive,DRQ_STAT,BUSY_STAT,WAIT_READY)) {
        printk (KERN_ERR "ide-tape: Strange, packet command initiated yet DRQ isn't asserted\n");
        return startstop;
    }
    ireason.all = IN_BYTE (IDE_IREASON_REG);
    while (retries-- && (!ireason.b.cod || ireason.b.io)) {
        printk(KERN_ERR "ide-tape: (IO,CoD != (0,1) while issuing a packet command, retrying\n");
        udelay(100);
        ireason.all = IN_BYTE(IDE_IREASON_REG);
        if (retries == 0) {
            printk(KERN_ERR "ide-tape: (IO,CoD != (0,1) while issuing a packet command, ignoring\n");
            ireason.b.cod = 1;
            ireason.b.io = 0;
        }
    }
    if (!ireason.b.cod || ireason.b.io) {
        printk (KERN_ERR "ide-tape: (IO,CoD) != (0,1) while issuing a packet command\n");
        return ide_do_reset (drive);
    }
    tape->cmd_start_time = jiffies;
    ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);    /* Set the interrupt routine */
    atapi_output_bytes (drive,pc->c,12);            /* Send the actual packet */
    return ide_started;
}

static ide_startstop_t idetape_issue_packet_command (ide_drive_t *drive, idetape_pc_t *pc)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_bcount_reg_t bcount;
    int dma_ok = 0;

#if IDETAPE_DEBUG_BUGS
    if (tape->pc->c[0] == IDETAPE_REQUEST_SENSE_CMD && pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
        printk (KERN_ERR "ide-tape: possible ide-tape.c bug - Two request sense in serial were issued\n");
    }
#endif /* IDETAPE_DEBUG_BUGS */

    if (tape->failed_pc == NULL && pc->c[0] != IDETAPE_REQUEST_SENSE_CMD)
        tape->failed_pc = pc;
    tape->pc = pc;                            /* Set the current packet command */

    if (pc->retries > IDETAPE_MAX_PC_RETRIES || test_bit (PC_ABORT, &pc->flags)) {
        /*
         *    We will "abort" retrying a packet command in case
         *    a legitimate error code was received (crossing a
         *    filemark, or DMA error in the end of media, for
         *    example).
         */
        if (!test_bit (PC_ABORT, &pc->flags)) {
            if (!(pc->c[0] == IDETAPE_TEST_UNIT_READY_CMD && tape->sense_key == 2 &&
                  tape->asc == 4 && (tape->ascq == 1 || tape->ascq == 8))) {
                printk (KERN_ERR "ide-tape: %s: I/O error, pc = %2x, key = %2x, asc = %2x, ascq = %2x\n",
                    tape->name, pc->c[0], tape->sense_key, tape->asc, tape->ascq);
                if (tape->onstream && pc->c[0] == IDETAPE_READ_CMD && tape->sense_key == 3 && tape->asc == 0x11)  /* AJN-1: 11 should be 0x11 */
                    printk(KERN_ERR "ide-tape: %s: enabling read error recovery\n", tape->name);
            }
            pc->error = IDETAPE_ERROR_GENERAL;        /* Giving up */
        }
        tape->failed_pc = NULL;
        return pc->callback(drive);
    }
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 2)
        printk (KERN_INFO "ide-tape: Retry number - %d\n", pc->retries);
#endif /* IDETAPE_DEBUG_LOG */

    pc->retries++;
    pc->actually_transferred = 0;                    /* We haven't transferred any data yet */
    pc->current_position=pc->buffer;
    bcount.all=pc->request_transfer;                /* Request to transfer the entire buffer at once */

#ifdef CONFIG_BLK_DEV_IDEDMA
    if (test_and_clear_bit (PC_DMA_ERROR, &pc->flags)) {
        printk (KERN_WARNING "ide-tape: DMA disabled, reverting to PIO\n");
        (void) HWIF(drive)->dmaproc(ide_dma_off, drive);
    }
    if (test_bit (PC_DMA_RECOMMENDED, &pc->flags) && drive->using_dma)
        dma_ok = !HWIF(drive)->dmaproc(test_bit (PC_WRITING, &pc->flags) ? ide_dma_write : ide_dma_read, drive);
#endif /* CONFIG_BLK_DEV_IDEDMA */

    if (IDE_CONTROL_REG)
        OUT_BYTE (drive->ctl, IDE_CONTROL_REG);
    OUT_BYTE (dma_ok ? 1 : 0,    IDE_FEATURE_REG);            /* Use PIO/DMA */
    OUT_BYTE (bcount.b.high,     IDE_BCOUNTH_REG);
    OUT_BYTE (bcount.b.low,      IDE_BCOUNTL_REG);
    OUT_BYTE (drive->select.all, IDE_SELECT_REG);
#ifdef CONFIG_BLK_DEV_IDEDMA
    if (dma_ok) {                        /* Begin DMA, if necessary */
        set_bit (PC_DMA_IN_PROGRESS, &pc->flags);
        (void) (HWIF(drive)->dmaproc(ide_dma_begin, drive));
    }
#endif /* CONFIG_BLK_DEV_IDEDMA */
    if (test_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags)) {
        ide_set_handler(drive, &idetape_transfer_pc, IDETAPE_WAIT_CMD, NULL);
        OUT_BYTE(WIN_PACKETCMD, IDE_COMMAND_REG);
        return ide_started;
    } else {
        OUT_BYTE(WIN_PACKETCMD, IDE_COMMAND_REG);
        return idetape_transfer_pc(drive);
    }
}

/*
 *    General packet command callback function.
 */
static ide_startstop_t idetape_pc_callback (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_pc_callback\n");
#endif /* IDETAPE_DEBUG_LOG */

    idetape_end_request (tape->pc->error ? 0 : 1, HWGROUP(drive));
    return ide_stopped;
}

/*
 *    A mode sense command is used to "sense" tape parameters.
 */
static void idetape_create_mode_sense_cmd (idetape_pc_t *pc, byte page_code)
{
    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_MODE_SENSE_CMD;
    if (page_code != IDETAPE_BLOCK_DESCRIPTOR)
        pc->c[1] = 8;            /* DBD = 1 - Don't return block descriptors */
    pc->c[2] = page_code;
    pc->c[3] = 255;                /* Don't limit the returned information */
    pc->c[4] = 255;                /* (We will just discard data in that case) */
    if (page_code == IDETAPE_BLOCK_DESCRIPTOR)
        pc->request_transfer = 12;
    else if (page_code == IDETAPE_CAPABILITIES_PAGE)
        pc->request_transfer = 24;
    else
        pc->request_transfer = 50;
    pc->callback = &idetape_pc_callback;
}

static ide_startstop_t idetape_onstream_buffer_fill_callback (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

    tape->max_frames = tape->pc->buffer[4 + 2];
    tape->cur_frames = tape->pc->buffer[4 + 3];
    if (tape->chrdev_direction == idetape_direction_write)
        tape->tape_head = tape->buffer_head - tape->cur_frames;
    else
        tape->tape_head = tape->buffer_head + tape->cur_frames;
    if (tape->tape_head != tape->last_tape_head) {
        tape->last_tape_head = tape->tape_head;
        tape->tape_still_time_begin = jiffies;
        if (tape->tape_still_time > 200)
            tape->measure_insert_time = 1;
    }
    tape->tape_still_time = (jiffies - tape->tape_still_time_begin) * 1000 / HZ;
#if USE_IOTRACE
    IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 1)
        printk(KERN_INFO "ide-tape: buffer fill callback, %d/%d\n", tape->cur_frames, tape->max_frames);
#endif
    idetape_end_request (tape->pc->error ? 0 : 1, HWGROUP(drive));
    return ide_stopped;
}

static void idetape_queue_onstream_buffer_fill (ide_drive_t *drive)
{
    idetape_pc_t *pc;
    struct request *rq;

    pc = idetape_next_pc_storage (drive);
    rq = idetape_next_rq_storage (drive);
    idetape_create_mode_sense_cmd (pc, IDETAPE_BUFFER_FILLING_PAGE);
    pc->callback = idetape_onstream_buffer_fill_callback;
    idetape_queue_pc_head (drive, pc, rq);
}

static void calculate_speeds(ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    int full = 125, empty = 75;

    if (jiffies > tape->controlled_pipeline_head_time + 120 * HZ) {
        tape->controlled_previous_pipeline_head = tape->controlled_last_pipeline_head;
        tape->controlled_previous_head_time = tape->controlled_pipeline_head_time;
        tape->controlled_last_pipeline_head = tape->pipeline_head;
        tape->controlled_pipeline_head_time = jiffies;
    }
    if (jiffies > tape->controlled_pipeline_head_time + 60 * HZ)
        tape->controlled_pipeline_head_speed = (tape->pipeline_head - tape->controlled_last_pipeline_head) * 32 * HZ / (jiffies - tape->controlled_pipeline_head_time);
    else if (jiffies > tape->controlled_previous_head_time)
        tape->controlled_pipeline_head_speed = (tape->pipeline_head - tape->controlled_previous_pipeline_head) * 32 * HZ / (jiffies - tape->controlled_previous_head_time);

    if (tape->nr_pending_stages < tape->max_stages /*- 1 */) { /* -1 for read mode error recovery */
        if (jiffies > tape->uncontrolled_previous_head_time + 10 * HZ) {
            tape->uncontrolled_pipeline_head_time = jiffies;
            tape->uncontrolled_pipeline_head_speed = (tape->pipeline_head - tape->uncontrolled_previous_pipeline_head) * 32 * HZ / (jiffies - tape->uncontrolled_previous_head_time);
        }
    } else {
        tape->uncontrolled_previous_head_time = jiffies;
        tape->uncontrolled_previous_pipeline_head = tape->pipeline_head;
        if (jiffies > tape->uncontrolled_pipeline_head_time + 30 * HZ) {
            tape->uncontrolled_pipeline_head_time = jiffies;
        }
    }
    tape->pipeline_head_speed = IDE_MAX(tape->uncontrolled_pipeline_head_speed, tape->controlled_pipeline_head_speed);
    if (tape->speed_control == 0) {
        tape->max_insert_speed = 5000;
    } else if (tape->speed_control == 1) {
        if (tape->nr_pending_stages >= tape->max_stages / 2)
            tape->max_insert_speed = tape->pipeline_head_speed +
                (1100 - tape->pipeline_head_speed) * 2 * (tape->nr_pending_stages - tape->max_stages / 2) / tape->max_stages;
        else
            tape->max_insert_speed = 500 +
                (tape->pipeline_head_speed - 500) * 2 * tape->nr_pending_stages / tape->max_stages;
        if (tape->nr_pending_stages >= tape->max_stages * 99 / 100)
            tape->max_insert_speed = 5000;
    } else if (tape->speed_control == 2) {
        tape->max_insert_speed = tape->pipeline_head_speed * empty / 100 +
            (tape->pipeline_head_speed * full / 100 - tape->pipeline_head_speed * empty / 100) * tape->nr_pending_stages / tape->max_stages;
    } else
        tape->max_insert_speed = tape->speed_control;
    tape->max_insert_speed = IDE_MAX(tape->max_insert_speed, 500);
}

static ide_startstop_t idetape_media_access_finished (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t *pc = tape->pc;
    idetape_status_reg_t status;

    if (tape->onstream)
        printk(KERN_INFO "ide-tape: bug: onstream, media_access_finished\n");
    status.all = GET_STAT();
    if (status.b.dsc) {
        if (status.b.check) {                    /* Error detected */
            printk (KERN_ERR "ide-tape: %s: I/O error, ",tape->name);
            return idetape_retry_pc (drive);            /* Retry operation */
        }
        pc->error = 0;
        if (tape->failed_pc == pc)
            tape->failed_pc = NULL;
    } else {
        pc->error = IDETAPE_ERROR_GENERAL;
        tape->failed_pc = NULL;
    }
    return pc->callback (drive);
}

static ide_startstop_t idetape_rw_callback (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    struct request *rq = HWGROUP(drive)->rq;
    int blocks = tape->pc->actually_transferred / tape->tape_block_size;

    tape->avg_size += blocks * tape->tape_block_size;
    tape->insert_size += blocks * tape->tape_block_size;
    if (tape->insert_size > 1024 * 1024)
        tape->measure_insert_time = 1;
    if (tape->measure_insert_time) {
        tape->measure_insert_time = 0;
        tape->insert_time = jiffies;
        tape->insert_size = 0;
    }
    if (jiffies > tape->insert_time)
        tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
    if (jiffies - tape->avg_time >= HZ) {
        tape->avg_speed = tape->avg_size * HZ / (jiffies - tape->avg_time) / 1024;
        tape->avg_size = 0;
        tape->avg_time = jiffies;
    }

#if IDETAPE_DEBUG_LOG    
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_rw_callback\n");
#endif /* IDETAPE_DEBUG_LOG */

    tape->first_frame_position += blocks;
    rq->current_nr_sectors -= blocks;

    if (!tape->pc->error)
        idetape_end_request (1, HWGROUP (drive));
    else
        idetape_end_request (tape->pc->error, HWGROUP (drive));
    return ide_stopped;
}

static void idetape_create_read_cmd (idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct buffer_head *bh)
{
    struct buffer_head *p = bh;
    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_READ_CMD;
    put_unaligned (htonl (length), (unsigned int *) &pc->c[1]);
    pc->c[1] = 1;
    pc->callback = &idetape_rw_callback;
    pc->bh = bh;
    atomic_set(&bh->b_count, 0);
    pc->buffer = NULL;
    if (tape->onstream) {
        while (p) {
            atomic_set(&p->b_count, 0);
            p = p->b_reqnext;
        }
    }
    if (!tape->onstream) {
        pc->request_transfer = pc->buffer_size = length * tape->tape_block_size;
        if (pc->request_transfer == tape->stage_size)
            set_bit (PC_DMA_RECOMMENDED, &pc->flags);
    } else  {
        if (length) {
            pc->request_transfer = pc->buffer_size = 32768 + 512;
            set_bit (PC_DMA_RECOMMENDED, &pc->flags);
        } else
            pc->request_transfer = 0;
    }
}

static void idetape_create_read_buffer_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct buffer_head *bh)
{
    int size = 32768;

    struct buffer_head *p = bh;
    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_READ_BUFFER_CMD;
    pc->c[1] = IDETAPE_RETRIEVE_FAULTY_BLOCK;
    pc->c[7] = size >> 8;
    pc->c[8] = size & 0xff;
    pc->callback = &idetape_pc_callback;
    pc->bh = bh;
    atomic_set(&bh->b_count, 0);
    pc->buffer = NULL;
    while (p) {
        atomic_set(&p->b_count, 0);
        p = p->b_reqnext;
    }
    pc->request_transfer = pc->buffer_size = size;
}

static void idetape_create_write_cmd (idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct buffer_head *bh)
{
    struct buffer_head *p = bh;
    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_WRITE_CMD;
    put_unaligned (htonl (length), (unsigned int *) &pc->c[1]);
    pc->c[1] = 1;
    pc->callback = &idetape_rw_callback;
    set_bit (PC_WRITING, &pc->flags);
    if (tape->onstream) {
        while (p) {
            atomic_set(&p->b_count, p->b_size);
            p = p->b_reqnext;
        }
    }
    pc->bh = bh;
    pc->b_data = bh->b_data;
    pc->b_count = atomic_read(&bh->b_count);
    pc->buffer = NULL;
    if (!tape->onstream) {
        pc->request_transfer = pc->buffer_size = length * tape->tape_block_size;
        if (pc->request_transfer == tape->stage_size)
            set_bit (PC_DMA_RECOMMENDED, &pc->flags);
    } else  {
        if (length) {
            pc->request_transfer = pc->buffer_size = 32768 + 512;
            set_bit (PC_DMA_RECOMMENDED, &pc->flags);
        } else
            pc->request_transfer = 0;
    }
}

/*
 *    idetape_do_request is our request handling function.    
 */
static ide_startstop_t idetape_do_request (ide_drive_t *drive, struct request *rq, unsigned long block)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t *pc;
    struct request *postponed_rq = tape->postponed_rq;
    idetape_status_reg_t status;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 5)
        printk (KERN_INFO "ide-tape: rq_status: %d, rq_dev: %u, cmd: %d, errors: %d\n",rq->rq_status,(unsigned int) rq->rq_dev,rq->cmd,rq->errors);
    if (tape->debug_level >= 2)
        printk (KERN_INFO "ide-tape: sector: %ld, nr_sectors: %ld, current_nr_sectors: %ld\n",rq->sector,rq->nr_sectors,rq->current_nr_sectors);
#endif /* IDETAPE_DEBUG_LOG */

    if (!IDETAPE_RQ_CMD (rq->cmd)) {
        /*
         *    We do not support buffer cache originated requests.
         */
        printk (KERN_NOTICE "ide-tape: %s: Unsupported command in request queue (%d)\n", drive->name, rq->cmd);
        ide_end_request (0, HWGROUP (drive));            /* Let the common code handle it */
        return ide_stopped;
    }

    /*
     *    Retry a failed packet command
     */
    if (tape->failed_pc != NULL && tape->pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
        return idetape_issue_packet_command (drive, tape->failed_pc);
    }
#if IDETAPE_DEBUG_BUGS
    if (postponed_rq != NULL)
        if (rq != postponed_rq) {
            printk (KERN_ERR "ide-tape: ide-tape.c bug - Two DSC requests were queued\n");
            idetape_end_request (0, HWGROUP (drive));
            return ide_stopped;
        }
#endif /* IDETAPE_DEBUG_BUGS */

    tape->postponed_rq = NULL;

    /*
     *    If the tape is still busy, postpone our request and service
     *    the other device meanwhile.
     */
    status.all = GET_STAT();

    /*
     * The OnStream tape drive doesn't support DSC. Assume
     * that DSC is always set.
     */
    if (tape->onstream)
        status.b.dsc = 1;
    if (!drive->dsc_overlap && rq->cmd != IDETAPE_PC_RQ2)
        set_bit (IDETAPE_IGNORE_DSC, &tape->flags);

    /*
     * For the OnStream tape, check the current status of the tape
     * internal buffer using data gathered from the buffer fill
     * mode page, and postpone our request, effectively "disconnecting"
     * from the IDE bus, in case the buffer is full (writing) or
     * empty (reading), and there is a danger that our request will
     * hold the IDE bus during actual media access.
     */
    if (tape->tape_still_time > 100 && tape->tape_still_time < 200)
        tape->measure_insert_time = 1;
    if (tape->req_buffer_fill && (rq->cmd == IDETAPE_WRITE_RQ || rq->cmd == IDETAPE_READ_RQ)) {
        tape->req_buffer_fill = 0;
        tape->writes_since_buffer_fill = 0;
        tape->reads_since_buffer_fill = 0;
        tape->last_buffer_fill = jiffies;
        idetape_queue_onstream_buffer_fill(drive);
        if (jiffies > tape->insert_time)
            tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
        return ide_stopped;
    }
    if (jiffies > tape->insert_time)
        tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
    calculate_speeds(drive);
    if (tape->onstream && tape->max_frames &&
        ((rq->cmd == IDETAPE_WRITE_RQ &&
              ( tape->cur_frames == tape->max_frames ||
                ( tape->speed_control && tape->cur_frames > 5 &&
                       (tape->insert_speed > tape->max_insert_speed ||
                        (0 /* tape->cur_frames > 30 && tape->tape_still_time > 200 */) ) ) ) ) ||
         (rq->cmd == IDETAPE_READ_RQ &&
          ( tape->cur_frames == 0 ||
        ( tape->speed_control && (tape->cur_frames < tape->max_frames - 5) &&
            tape->insert_speed > tape->max_insert_speed ) ) && rq->nr_sectors) ) ) {
#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 4)
            printk(KERN_INFO "ide-tape: postponing request, cmd %d, cur %d, max %d\n",
                rq->cmd, tape->cur_frames, tape->max_frames);
#endif
        if (tape->postpone_cnt++ < 500) {
            status.b.dsc = 0;
            tape->req_buffer_fill = 1;
        }
#if ONSTREAM_DEBUG
        else if (tape->debug_level >= 4) 
            printk(KERN_INFO "ide-tape: %s: postpone_cnt %d\n", tape->name, tape->postpone_cnt);
#endif
    }
    if (!test_and_clear_bit (IDETAPE_IGNORE_DSC, &tape->flags) && !status.b.dsc) {
        if (postponed_rq == NULL) {
            tape->dsc_polling_start = jiffies;
            tape->dsc_polling_frequency = tape->best_dsc_rw_frequency;
            tape->dsc_timeout = jiffies + IDETAPE_DSC_RW_TIMEOUT;
        } else if ((signed long) (jiffies - tape->dsc_timeout) > 0) {
            printk (KERN_ERR "ide-tape: %s: DSC timeout\n", tape->name);
            if (rq->cmd == IDETAPE_PC_RQ2) {
                idetape_media_access_finished (drive);
                return ide_stopped;
            } else {
                return ide_do_reset (drive);
            }
        } else if (jiffies - tape->dsc_polling_start > IDETAPE_DSC_MA_THRESHOLD)
            tape->dsc_polling_frequency = IDETAPE_DSC_MA_SLOW;
        idetape_postpone_request (drive);
        return ide_stopped;
    }
    switch (rq->cmd) {
        case IDETAPE_READ_RQ:
            tape->buffer_head++;
#if USE_IOTRACE
            IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
            tape->postpone_cnt = 0;
            tape->reads_since_buffer_fill++;
            if (tape->onstream) {
                if (tape->cur_frames - tape->reads_since_buffer_fill <= 0)
                    tape->req_buffer_fill = 1;
                if (jiffies > tape->last_buffer_fill + 5 * HZ / 100)
                    tape->req_buffer_fill = 1;
            }
            pc = idetape_next_pc_storage (drive);
            idetape_create_read_cmd (tape, pc, rq->current_nr_sectors, rq->bh);
            break;
        case IDETAPE_WRITE_RQ:
            tape->buffer_head++;
#if USE_IOTRACE
            IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
            tape->postpone_cnt = 0;
            tape->writes_since_buffer_fill++;
            if (tape->onstream) {
                if (tape->cur_frames + tape->writes_since_buffer_fill >= tape->max_frames)
                    tape->req_buffer_fill = 1;
                if (jiffies > tape->last_buffer_fill + 5 * HZ / 100)
                    tape->req_buffer_fill = 1;
                calculate_speeds(drive);
            }
            pc = idetape_next_pc_storage (drive);
            idetape_create_write_cmd (tape, pc, rq->current_nr_sectors, rq->bh);
            break;
        case IDETAPE_READ_BUFFER_RQ:
            tape->postpone_cnt = 0;
            pc = idetape_next_pc_storage (drive);
            idetape_create_read_buffer_cmd (tape, pc, rq->current_nr_sectors, rq->bh);
            break;
        case IDETAPE_ABORTED_WRITE_RQ:
            rq->cmd = IDETAPE_WRITE_RQ;
            idetape_end_request (IDETAPE_ERROR_EOD, HWGROUP(drive));
            return ide_stopped;
        case IDETAPE_ABORTED_READ_RQ:
#if IDETAPE_DEBUG_LOG
            if (tape->debug_level >= 2)
                printk(KERN_INFO "ide-tape: %s: detected aborted read rq\n", tape->name);
#endif
            rq->cmd = IDETAPE_READ_RQ;
            idetape_end_request (IDETAPE_ERROR_EOD, HWGROUP(drive));
            return ide_stopped;
        case IDETAPE_PC_RQ1:
            pc = (idetape_pc_t *) rq->buffer;
            rq->cmd = IDETAPE_PC_RQ2;
            break;
        case IDETAPE_PC_RQ2:
            idetape_media_access_finished (drive);
            return ide_stopped;
        default:
            printk (KERN_ERR "ide-tape: bug in IDETAPE_RQ_CMD macro\n");
            idetape_end_request (0, HWGROUP (drive));
            return ide_stopped;
    }
    return idetape_issue_packet_command (drive, pc);
}

/*
 *    Pipeline related functions
 */
static inline int idetape_pipeline_active (idetape_tape_t *tape)
{
    int rc1, rc2;

    rc1 = test_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
    rc2 = (tape->active_data_request != NULL);
    return rc1;
}

/*
 *    idetape_kmalloc_stage uses __get_free_page to allocate a pipeline
 *    stage, along with all the necessary small buffers which together make
 *    a buffer of size tape->stage_size (or a bit more). We attempt to
 *    combine sequential pages as much as possible.
 *
 *    Returns a pointer to the new allocated stage, or NULL if we
 *    can't (or don't want to) allocate a stage.
 *
 *    Pipeline stages are optional and are used to increase performance.
 *    If we can't allocate them, we'll manage without them.
 */
static idetape_stage_t *__idetape_kmalloc_stage (idetape_tape_t *tape, int full, int clear)
{
    idetape_stage_t *stage;
    struct buffer_head *prev_bh, *bh;
    int pages = tape->pages_per_stage;
    char *b_data;

    if ((stage = (idetape_stage_t *) kmalloc (sizeof (idetape_stage_t),GFP_KERNEL)) == NULL)
        return NULL;
    stage->next = NULL;

    bh = stage->bh = (struct buffer_head *) kmalloc (sizeof (struct buffer_head), GFP_KERNEL);
    if (bh == NULL)
        goto abort;
    bh->b_reqnext = NULL;
    if ((bh->b_data = (char *) __get_free_page (GFP_KERNEL)) == NULL)
        goto abort;
    if (clear)
        memset(bh->b_data, 0, PAGE_SIZE);
    bh->b_size = PAGE_SIZE;
    atomic_set(&bh->b_count, full ? bh->b_size : 0);
    set_bit (BH_Lock, &bh->b_state);

    while (--pages) {
        if ((b_data = (char *) __get_free_page (GFP_KERNEL)) == NULL)
            goto abort;
        if (clear)
            memset(b_data, 0, PAGE_SIZE);
        if (bh->b_data == b_data + PAGE_SIZE) {
            bh->b_size += PAGE_SIZE;
            bh->b_data -= PAGE_SIZE;
            if (full)
                atomic_add(PAGE_SIZE, &bh->b_count);
            continue;
        }
        if (b_data == bh->b_data + bh->b_size) {
            bh->b_size += PAGE_SIZE;
            if (full)
                atomic_add(PAGE_SIZE, &bh->b_count);
            continue;
        }
        prev_bh = bh;
        if ((bh = (struct buffer_head *) kmalloc (sizeof (struct buffer_head), GFP_KERNEL)) == NULL) {
            free_page ((unsigned long) b_data);
            goto abort;
        }
        bh->b_reqnext = NULL;
        bh->b_data = b_data;
        bh->b_size = PAGE_SIZE;
        atomic_set(&bh->b_count, full ? bh->b_size : 0);
        set_bit (BH_Lock, &bh->b_state);
        prev_bh->b_reqnext = bh;
    }
    bh->b_size -= tape->excess_bh_size;
    if (full)
        atomic_sub(tape->excess_bh_size, &bh->b_count);
    if (tape->onstream)
        stage->aux = (os_aux_t *) (bh->b_data + bh->b_size - OS_AUX_SIZE);
    return stage;
abort:
    __idetape_kfree_stage (stage);
    return NULL;
}

static idetape_stage_t *idetape_kmalloc_stage (idetape_tape_t *tape)
{
    idetape_stage_t *cache_stage = tape->cache_stage;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_kmalloc_stage\n");
#endif /* IDETAPE_DEBUG_LOG */

    if (tape->nr_stages >= tape->max_stages)
        return NULL;
    if (cache_stage != NULL) {
        tape->cache_stage = NULL;
        return cache_stage;
    }
    return __idetape_kmalloc_stage (tape, 0, 0);
}

static void idetape_copy_stage_from_user (idetape_tape_t *tape, idetape_stage_t *stage, const char *buf, int n)
{
    struct buffer_head *bh = tape->bh;
    int count;

    while (n) {
#if IDETAPE_DEBUG_BUGS
        if (bh == NULL) {
            printk (KERN_ERR "ide-tape: bh == NULL in idetape_copy_stage_from_user\n");
            return;
        }
#endif /* IDETAPE_DEBUG_BUGS */
        count = IDE_MIN (bh->b_size - atomic_read(&bh->b_count), n);
        copy_from_user (bh->b_data + atomic_read(&bh->b_count), buf, count);
        n -= count;
        atomic_add(count, &bh->b_count);
        buf += count;
        if (atomic_read(&bh->b_count) == bh->b_size) {
            bh = bh->b_reqnext;
            if (bh)
                atomic_set(&bh->b_count, 0);
        }
    }
    tape->bh = bh;
}

static void idetape_copy_stage_to_user (idetape_tape_t *tape, char *buf, idetape_stage_t *stage, int n)
{
    struct buffer_head *bh = tape->bh;
    int count;

    while (n) {
#if IDETAPE_DEBUG_BUGS
        if (bh == NULL) {
            printk (KERN_ERR "ide-tape: bh == NULL in idetape_copy_stage_to_user\n");
            return;
        }
#endif /* IDETAPE_DEBUG_BUGS */
        count = IDE_MIN (tape->b_count, n);
        copy_to_user (buf, tape->b_data, count);
        n -= count;
        tape->b_data += count;
        tape->b_count -= count;
        buf += count;
        if (!tape->b_count) {
            tape->bh = bh = bh->b_reqnext;
            if (bh) {
                tape->b_data = bh->b_data;
                tape->b_count = atomic_read(&bh->b_count);
            }
        }
    }
}

static void idetape_init_merge_stage (idetape_tape_t *tape)
{
    struct buffer_head *bh = tape->merge_stage->bh;
    
    tape->bh = bh;
    if (tape->chrdev_direction == idetape_direction_write)
        atomic_set(&bh->b_count, 0);
    else {
        tape->b_data = bh->b_data;
        tape->b_count = atomic_read(&bh->b_count);
    }
}

static void idetape_switch_buffers (idetape_tape_t *tape, idetape_stage_t *stage)
{
    struct buffer_head *tmp;
    os_aux_t *tmp_aux;

    tmp = stage->bh; tmp_aux = stage->aux;
    stage->bh = tape->merge_stage->bh; stage->aux = tape->merge_stage->aux;
    tape->merge_stage->bh = tmp; tape->merge_stage->aux = tmp_aux;
    idetape_init_merge_stage (tape);
}

/*
 *    idetape_add_stage_tail adds a new stage at the end of the pipeline.
 */
static void idetape_add_stage_tail (ide_drive_t *drive,idetape_stage_t *stage)
{
    idetape_tape_t *tape = drive->driver_data;
    unsigned long flags;
    
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_add_stage_tail\n");
#endif /* IDETAPE_DEBUG_LOG */
    spin_lock_irqsave(&tape->spinlock, flags);
    stage->next=NULL;
    if (tape->last_stage != NULL)
        tape->last_stage->next=stage;
    else
        tape->first_stage = tape->next_stage=stage;
    tape->last_stage = stage;
    if (tape->next_stage == NULL)
        tape->next_stage = tape->last_stage;
    tape->nr_stages++;
    tape->nr_pending_stages++;
    spin_unlock_irqrestore(&tape->spinlock, flags);
}

/*
 * Initialize the OnStream AUX
 */
static void idetape_init_stage (ide_drive_t *drive, idetape_stage_t *stage, int frame_type, int logical_blk_num)
{
    idetape_tape_t *tape = drive->driver_data;
    os_aux_t *aux = stage->aux;
    os_partition_t *par = &aux->partition;
    os_dat_t *dat = &aux->dat;

    if (!tape->onstream || tape->raw)
        return;
    memset(aux, 0, sizeof(*aux));
    aux->format_id = htonl(0);
    memcpy(aux->application_sig, "LIN3", 4);
    aux->hdwr = htonl(0);
    aux->frame_type = frame_type;

    if (frame_type == OS_FRAME_TYPE_HEADER) {
        aux->update_frame_cntr = htonl(tape->update_frame_cntr);
        par->partition_num = OS_CONFIG_PARTITION;
        par->par_desc_ver = OS_PARTITION_VERSION;
        par->wrt_pass_cntr = htons(0xffff);
        par->first_frame_addr = htonl(0);
        par->last_frame_addr = htonl(0xbb7); /* 2999 */
        aux->frame_seq_num = htonl(0);
        aux->logical_blk_num_high = htonl(0);
        aux->logical_blk_num = htonl(0);
        aux->next_mark_addr = htonl(tape->first_mark_addr);
    } else {
        aux->update_frame_cntr = htonl(0);
        par->partition_num = OS_DATA_PARTITION;
        par->par_desc_ver = OS_PARTITION_VERSION;
        par->wrt_pass_cntr = htons(tape->wrt_pass_cntr);
        par->first_frame_addr = htonl(OS_DATA_STARTFRAME1);
        par->last_frame_addr = htonl(tape->capacity);
        aux->frame_seq_num = htonl(logical_blk_num);
        aux->logical_blk_num_high = htonl(0);
        aux->logical_blk_num = htonl(logical_blk_num);
        dat->dat_sz = 8;
        dat->reserved1 = 0;
        dat->entry_cnt = 1;
        dat->reserved3 = 0;
        if (frame_type == OS_FRAME_TYPE_DATA)
            dat->dat_list[0].blk_sz = htonl(32 * 1024);
        else
            dat->dat_list[0].blk_sz = 0;
        dat->dat_list[0].blk_cnt = htons(1);
        if (frame_type == OS_FRAME_TYPE_MARKER)
            dat->dat_list[0].flags = OS_DAT_FLAGS_MARK;
        else
            dat->dat_list[0].flags = OS_DAT_FLAGS_DATA;
        dat->dat_list[0].reserved = 0;
    } 
    aux->filemark_cnt = ntohl(tape->filemark_cnt);        /* shouldn't this be htonl ?? */
    aux->phys_fm = ntohl(0xffffffff);            /* shouldn't this be htonl ?? */
    aux->last_mark_addr = ntohl(tape->last_mark_addr);    /* shouldn't this be htonl ?? */
}

/*
 *    idetape_wait_for_request installs a completion in a pending request
 *    and sleeps until it is serviced.
 *
 *    The caller should ensure that the request will not be serviced
 *    before we install the completion (usually by disabling interrupts).
 */
static void idetape_wait_for_request (ide_drive_t *drive, struct request *rq)
{
    DECLARE_COMPLETION(wait);
    idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_BUGS
    if (rq == NULL || !IDETAPE_RQ_CMD (rq->cmd)) {
        printk (KERN_ERR "ide-tape: bug: Trying to sleep on non-valid request\n");
        return;
    }
#endif /* IDETAPE_DEBUG_BUGS */
    rq->waiting = &wait;
    tape->waiting = &wait;
    spin_unlock(&tape->spinlock);
    wait_for_completion(&wait);
    rq->waiting = NULL;
    tape->waiting = NULL;
    spin_lock_irq(&tape->spinlock);
}

static ide_startstop_t idetape_read_position_callback (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_read_position_result_t *result;
    
//#if IDETAPE_DEBUG_LOG
//    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_read_position_callback\n");
//#endif /* IDETAPE_DEBUG_LOG */

    if (!tape->pc->error) {
        result = (idetape_read_position_result_t *) tape->pc->buffer;
#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 2)
            printk (KERN_INFO "ide-tape: BOP - %s\n",result->bop ? "Yes":"No");
        if (tape->debug_level >= 2)
            printk (KERN_INFO "ide-tape: EOP - %s\n",result->eop ? "Yes":"No");
#endif /* IDETAPE_DEBUG_LOG */
        if (result->bpu) {
            printk (KERN_INFO "ide-tape: Block location is unknown to the tape\n");
            clear_bit (IDETAPE_ADDRESS_VALID, &tape->flags);
            idetape_end_request (0, HWGROUP (drive));
        } else {
#if IDETAPE_DEBUG_LOG
            if (tape->debug_level >= 2)
                printk (KERN_INFO "ide-tape: Block Location - %u\n", ntohl (result->first_block));
#endif /* IDETAPE_DEBUG_LOG */
            tape->partition = result->partition;
            tape->first_frame_position = ntohl (result->first_block);
            tape->last_frame_position = ntohl (result->last_block);
            tape->blocks_in_buffer = result->blocks_in_buffer[2];
            set_bit (IDETAPE_ADDRESS_VALID, &tape->flags);
            idetape_end_request (1, HWGROUP (drive));
        }
    } else {
        idetape_end_request (0, HWGROUP (drive));
    }
    return ide_stopped;
}

/*
 *    idetape_create_write_filemark_cmd will:
 *
 *        1.    Write a filemark if write_filemark=1.
 *        2.    Flush the device buffers without writing a filemark
 *            if write_filemark=0.
 *
 */
static void idetape_create_write_filemark_cmd (ide_drive_t *drive, idetape_pc_t *pc,int write_filemark)
{
    idetape_tape_t *tape = drive->driver_data;

    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_WRITE_FILEMARK_CMD;
    if (tape->onstream)
        pc->c[1] = 1; /* Immed bit */
    pc->c[4] = write_filemark;  /* not used for OnStream ?? */
    set_bit (PC_WAIT_FOR_DSC, &pc->flags);
    pc->callback = &idetape_pc_callback;
}

static void idetape_create_test_unit_ready_cmd(idetape_pc_t *pc)
{
    idetape_init_pc(pc);
    pc->c[0] = IDETAPE_TEST_UNIT_READY_CMD;
    pc->callback = &idetape_pc_callback;
}

/*
 *    idetape_queue_pc_tail is based on the following functions:
 *
 *    ide_do_drive_cmd from ide.c
 *    cdrom_queue_request and cdrom_queue_packet_command from ide-cd.c
 *
 *    We add a special packet command request to the tail of the request queue,
 *    and wait for it to be serviced.
 *
 *    This is not to be called from within the request handling part
 *    of the driver ! We allocate here data in the stack, and it is valid
 *    until the request is finished. This is not the case for the bottom
 *    part of the driver, where we are always leaving the functions to wait
 *    for an interrupt or a timer event.
 *
 *    From the bottom part of the driver, we should allocate safe memory
 *    using idetape_next_pc_storage and idetape_next_rq_storage, and add
 *    the request to the request list without waiting for it to be serviced !
 *    In that case, we usually use idetape_queue_pc_head.
 */
static int __idetape_queue_pc_tail (ide_drive_t *drive, idetape_pc_t *pc)
{
    struct request rq;

    ide_init_drive_cmd (&rq);
    rq.buffer = (char *) pc;
    rq.cmd = IDETAPE_PC_RQ1;
    return ide_do_drive_cmd (drive, &rq, ide_wait);
}

static void idetape_create_load_unload_cmd (ide_drive_t *drive, idetape_pc_t *pc,int cmd)
{
    idetape_tape_t *tape = drive->driver_data;

    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_LOAD_UNLOAD_CMD;
    pc->c[4] = cmd;
    if (tape->onstream) {
        pc->c[1] = 1;
        if (cmd == !IDETAPE_LU_LOAD_MASK)
            pc->c[4] = 4;
    }
    set_bit (PC_WAIT_FOR_DSC, &pc->flags);
    pc->callback = &idetape_pc_callback;
}

static int idetape_wait_ready (ide_drive_t *drive, unsigned long long timeout)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t pc;

    /*
     * Wait for the tape to become ready
     */
    timeout += jiffies;
    while (jiffies < timeout) {
        idetape_create_test_unit_ready_cmd(&pc);
        if (!__idetape_queue_pc_tail(drive, &pc))
            return 0;
        if (tape->sense_key == 2 && tape->asc == 4 && tape->ascq == 2) {
            idetape_create_load_unload_cmd (drive, &pc, IDETAPE_LU_LOAD_MASK);
            __idetape_queue_pc_tail(drive, &pc);
            idetape_create_test_unit_ready_cmd(&pc);
            if (!__idetape_queue_pc_tail(drive, &pc))
                return 0;
        }
        if (!(tape->sense_key == 2 && tape->asc == 4 && (tape->ascq == 1 || tape->ascq == 8)))
            break;
        current->state = TASK_INTERRUPTIBLE;
          schedule_timeout(HZ / 10);
    }
    return -EIO;
}

static int idetape_queue_pc_tail (ide_drive_t *drive,idetape_pc_t *pc)
{
    idetape_tape_t *tape = drive->driver_data;
    int rc;

    rc = __idetape_queue_pc_tail(drive, pc);
    if (rc)
        return rc;
    if (tape->onstream && test_bit(PC_WAIT_FOR_DSC, &pc->flags))
        rc = idetape_wait_ready(drive, 60 * 10 * HZ);   /* AJN-4: Changed from 5 to 10 minutes;
                          because retension takes approx. 8:20 with Onstream 30GB tape */
    return rc;
}

static int idetape_flush_tape_buffers (ide_drive_t *drive)
{
    idetape_pc_t pc;
    int rc;

    idetape_create_write_filemark_cmd(drive, &pc, 0);
    if ((rc = idetape_queue_pc_tail (drive, &pc)))
        return rc;
    idetape_wait_ready(drive, 60 * 5 * HZ);
    return 0;
}

static void idetape_create_read_position_cmd (idetape_pc_t *pc)
{
    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_READ_POSITION_CMD;
    pc->request_transfer = 20;
    pc->callback = &idetape_read_position_callback;
}

static int idetape_read_position (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t pc;
    int position;

//#if IDETAPE_DEBUG_LOG
//        if (tape->debug_level >= 4)
    printk (KERN_INFO "ide-tape: Reached idetape_read_position\n");
//#endif /* IDETAPE_DEBUG_LOG */

#ifdef NO_LONGER_REQUIRED
    idetape_flush_tape_buffers(drive);
#endif
    idetape_create_read_position_cmd(&pc);
    if (idetape_queue_pc_tail (drive, &pc))
        return -1;
    position = tape->first_frame_position;
#ifdef NO_LONGER_REQUIRED
    if (tape->onstream) {
        if ((position != tape->last_frame_position - tape->blocks_in_buffer) &&
            (position != tape->last_frame_position + tape->blocks_in_buffer)) {
            if (tape->blocks_in_buffer == 0) {
                printk("ide-tape: %s: correcting read position %d, %d, %d\n", tape->name, position, tape->last_frame_position, tape->blocks_in_buffer);
                position = tape->last_frame_position;
                tape->first_frame_position = position;
            }
        }
    }
#endif
    return position;
}

static void idetape_create_locate_cmd (ide_drive_t *drive, idetape_pc_t *pc, unsigned int block, byte partition, int skip)
{
    idetape_tape_t *tape = drive->driver_data;

    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_LOCATE_CMD;
    if (tape->onstream)
        pc->c[1] = 1; /* Immediate bit */
    else
        pc->c[1] = 2;
    put_unaligned (htonl (block), (unsigned int *) &pc->c[3]);
    pc->c[8] = partition;
    if (tape->onstream)
                /*
                 * Set SKIP bit.
                 * In case of write error this will write buffered
                 * data in the drive to this new position!
                 */
        pc->c[9] = skip << 7;
    set_bit (PC_WAIT_FOR_DSC, &pc->flags);
    pc->callback = &idetape_pc_callback;
}

static int idetape_create_prevent_cmd (ide_drive_t *drive, idetape_pc_t *pc, int prevent)
{
    idetape_tape_t *tape = drive->driver_data;

    if (!tape->capabilities.lock)
        return 0;

    idetape_init_pc(pc);
    pc->c[0] = IDETAPE_PREVENT_CMD;
    pc->c[4] = prevent;
    pc->callback = &idetape_pc_callback;
    return 1;
}

static int __idetape_discard_read_pipeline (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    unsigned long flags;
    int cnt;

    if (tape->chrdev_direction != idetape_direction_read)
        return 0;
    tape->merge_stage_size = 0;
    if (tape->merge_stage != NULL) {
        __idetape_kfree_stage (tape->merge_stage);
        tape->merge_stage = NULL;
    }
    tape->chrdev_direction = idetape_direction_none;
    
    if (tape->first_stage == NULL)
        return 0;

    spin_lock_irqsave(&tape->spinlock, flags);
    tape->next_stage = NULL;
    if (idetape_pipeline_active (tape))
        idetape_wait_for_request(drive, tape->active_data_request);
    spin_unlock_irqrestore(&tape->spinlock, flags);

    cnt = tape->nr_stages - tape->nr_pending_stages;
    while (tape->first_stage != NULL)
        idetape_remove_stage_head (drive);
    tape->nr_pending_stages = 0;
    tape->max_stages = tape->min_pipeline;
    return cnt;
}

/*
 *    idetape_position_tape positions the tape to the requested block
 *    using the LOCATE packet command. A READ POSITION command is then
 *    issued to check where we are positioned.
 *
 *    Like all higher level operations, we queue the commands at the tail
 *    of the request queue and wait for their completion.
 *    
 */
static int idetape_position_tape (ide_drive_t *drive, unsigned int block, byte partition, int skip)
{
    idetape_tape_t *tape = drive->driver_data;
    int retval;
    idetape_pc_t pc;

    if (tape->chrdev_direction == idetape_direction_read)
        __idetape_discard_read_pipeline(drive);
    idetape_wait_ready(drive, 60 * 5 * HZ);
    idetape_create_locate_cmd (drive, &pc, block, partition, skip);
    retval = idetape_queue_pc_tail (drive, &pc);
    if (retval)
        return (retval);

    idetape_create_read_position_cmd (&pc);
    return (idetape_queue_pc_tail (drive, &pc));
}

static void idetape_discard_read_pipeline (ide_drive_t *drive, int restore_position)
{
    idetape_tape_t *tape = drive->driver_data;
    int cnt;
    int seek, position;

    cnt = __idetape_discard_read_pipeline(drive);
    if (restore_position) {
        position = idetape_read_position(drive);
#if ONSTREAM_DEBUG
        if (tape->debug_level >= 2)
            printk(KERN_INFO "ide-tape: address %u, nr_stages %d\n", position, cnt);
#endif
        seek = position > cnt ? position - cnt : 0;
        if (idetape_position_tape(drive, seek, 0, 0)) {
            printk(KERN_INFO "ide-tape: %s: position_tape failed in discard_pipeline()\n", tape->name);
            return;
        }
    }
}

static void idetape_update_stats (ide_drive_t *drive)
{
    idetape_pc_t pc;

    idetape_create_mode_sense_cmd (&pc, IDETAPE_BUFFER_FILLING_PAGE);
    pc.callback = idetape_onstream_buffer_fill_callback;
    (void) idetape_queue_pc_tail(drive, &pc);
}

/*
 *    idetape_queue_rw_tail generates a read/write request for the block
 *    device interface and wait for it to be serviced.
 */
static int idetape_queue_rw_tail (ide_drive_t *drive, int cmd, int blocks, struct buffer_head *bh)
{
    idetape_tape_t *tape = drive->driver_data;
    struct request rq;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 2)
        printk (KERN_INFO "ide-tape: idetape_queue_rw_tail: cmd=%d\n",cmd);
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
    if (idetape_pipeline_active (tape)) {
        printk (KERN_ERR "ide-tape: bug: the pipeline is active in idetape_queue_rw_tail\n");
        return (0);
    }
#endif /* IDETAPE_DEBUG_BUGS */    

    ide_init_drive_cmd (&rq);
    rq.bh = bh;
    rq.cmd = cmd;
    rq.sector = tape->first_frame_position;
    rq.nr_sectors = rq.current_nr_sectors = blocks;
    if (tape->onstream)
        tape->postpone_cnt = 600;
    (void) ide_do_drive_cmd (drive, &rq, ide_wait);

    if (cmd != IDETAPE_READ_RQ && cmd != IDETAPE_WRITE_RQ)
        return 0;

    if (tape->merge_stage)
        idetape_init_merge_stage (tape);
    if (rq.errors == IDETAPE_ERROR_GENERAL)
        return -EIO;
    return (tape->tape_block_size * (blocks-rq.current_nr_sectors));
}

/*
 * Read back the drive's internal buffer contents, as a part
 * of the write error recovery mechanism for old OnStream
 * firmware revisions.
 */
static void idetape_onstream_read_back_buffer (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    int frames, i, logical_blk_num;
    idetape_stage_t *stage, *first = NULL, *last = NULL;
    os_aux_t *aux;
    struct request *rq;
    unsigned char *p;
    unsigned long flags;

    idetape_update_stats(drive);
    frames = tape->cur_frames;
    logical_blk_num = ntohl(tape->first_stage->aux->logical_blk_num) - frames;
    printk(KERN_INFO "ide-tape: %s: reading back %d frames from the drive's internal buffer\n", tape->name, frames);
    for (i = 0; i < frames; i++) {
        stage = __idetape_kmalloc_stage(tape, 0, 0);
        if (!first)
            first = stage;
        aux = stage->aux;
        p = stage->bh->b_data;
        idetape_queue_rw_tail(drive, IDETAPE_READ_BUFFER_RQ, tape->capabilities.ctl, stage->bh);
#if ONSTREAM_DEBUG
        if (tape->debug_level >= 2)
            printk(KERN_INFO "ide-tape: %s: read back logical block %d, data %x %x %x %x\n", tape->name, logical_blk_num, *p++, *p++, *p++, *p++);
#endif
        rq = &stage->rq;
        ide_init_drive_cmd (rq);
        rq->cmd = IDETAPE_WRITE_RQ;
        rq->sector = tape->first_frame_position;
        rq->nr_sectors = rq->current_nr_sectors = tape->capabilities.ctl;
        idetape_init_stage(drive, stage, OS_FRAME_TYPE_DATA, logical_blk_num++);
        stage->next = NULL;
        if (last)
            last->next = stage;
        last = stage;
    }
    if (frames) {
        spin_lock_irqsave(&tape->spinlock, flags);
        last->next = tape->first_stage;
        tape->next_stage = tape->first_stage = first;
        tape->nr_stages += frames;
        tape->nr_pending_stages += frames;
        spin_unlock_irqrestore(&tape->spinlock, flags);
    }
    idetape_update_stats(drive);
#if ONSTREAM_DEBUG
    if (tape->debug_level >= 2)
        printk(KERN_INFO "ide-tape: %s: frames left in buffer: %d\n", tape->name, tape->cur_frames);
#endif
}

/*
 * Error recovery algorithm for the OnStream tape.
 */
static void idetape_onstream_write_error_recovery (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    unsigned int block;

    if (tape->onstream_write_error == OS_WRITE_ERROR) {
        printk(KERN_ERR "ide-tape: %s: onstream_write_error_recovery: detected physical bad block at %u, logical %u first frame %u last_frame %u bufblocks %u stages %u skipping %u frames\n",
            tape->name, ntohl(tape->sense.information), tape->logical_blk_num,
            tape->first_frame_position, tape->last_frame_position,
            tape->blocks_in_buffer, tape->nr_stages,
             (ntohl(tape->sense.command_specific) >> 16) & 0xff );
        block = ntohl(tape->sense.information) + ((ntohl(tape->sense.command_specific) >> 16) & 0xff);
        idetape_update_stats(drive);
        printk(KERN_ERR "ide-tape: %s: relocating %d buffered logical blocks to physical block %u\n", tape->name, tape->cur_frames, block);
#if 0  /* isn't once enough ??? MM */
        idetape_update_stats(drive);
#endif
        if (tape->firmware_revision_num >= 106)
            idetape_position_tape(drive, block, 0, 1);
        else {
            idetape_onstream_read_back_buffer(drive);
            idetape_position_tape(drive, block, 0, 0);
        }
#if 0     /* already done in idetape_position_tape MM */
        idetape_read_position(drive);
#endif
#if ONSTREAM_DEBUG
        if (tape->debug_level >= 1)
            printk(KERN_ERR "ide-tape: %s: positioning complete, cur_frames %d, pos %d, tape pos %d\n", tape->name, tape->cur_frames, tape->first_frame_position, tape->last_frame_position);
#endif
    } else if (tape->onstream_write_error == OS_PART_ERROR) {
#if ONSTREAM_DEBUG
        if (tape->debug_level >= 1)
            printk(KERN_INFO "ide-tape: %s: skipping over config partition\n", tape->name);
#endif
        idetape_flush_tape_buffers(drive);
        block = idetape_read_position(drive);
        if (block != OS_DATA_ENDFRAME1)  
            printk(KERN_ERR "ide-tape: warning, current position %d, expected %d\n", block, OS_DATA_ENDFRAME1);
        idetape_position_tape(drive, 0xbb8, 0, 0); /* 3000 */
    }
    tape->onstream_write_error = 0;
}

/*
 *    idetape_insert_pipeline_into_queue is used to start servicing the
 *    pipeline stages, starting from tape->next_stage.
 */
static void idetape_insert_pipeline_into_queue (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

    if (tape->next_stage == NULL)
        return;
    if (!idetape_pipeline_active (tape)) {
        if (tape->onstream_write_error)
            idetape_onstream_write_error_recovery(drive);
        set_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
        idetape_active_next_stage (drive);
        (void) ide_do_drive_cmd (drive, tape->active_data_request, ide_end);
    }
}

static void idetape_create_inquiry_cmd (idetape_pc_t *pc)
{
    idetape_init_pc(pc);
    pc->c[0] = IDETAPE_INQUIRY_CMD;
    pc->c[4] = pc->request_transfer = 254;
    pc->callback = &idetape_pc_callback;
}

static void idetape_create_rewind_cmd (ide_drive_t *drive, idetape_pc_t *pc)
{
    idetape_tape_t *tape = drive->driver_data;

    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_REWIND_CMD;
    if (tape->onstream)
        pc->c[1] = 1;
    set_bit (PC_WAIT_FOR_DSC, &pc->flags);
    pc->callback = &idetape_pc_callback;
}

static void idetape_create_mode_select_cmd (idetape_pc_t *pc, int length)
{
    idetape_init_pc (pc);
    set_bit (PC_WRITING, &pc->flags);
    pc->c[0] = IDETAPE_MODE_SELECT_CMD;
    pc->c[1] = 0x10;
    put_unaligned (htons(length), (unsigned short *) &pc->c[3]);
    pc->request_transfer = 255;
    pc->callback = &idetape_pc_callback;
}

static void idetape_create_erase_cmd (idetape_pc_t *pc)
{
    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_ERASE_CMD;
    pc->c[1] = 1;
    set_bit (PC_WAIT_FOR_DSC, &pc->flags);
    pc->callback = &idetape_pc_callback;
}

static void idetape_create_space_cmd (idetape_pc_t *pc,int count,byte cmd)
{
    idetape_init_pc (pc);
    pc->c[0] = IDETAPE_SPACE_CMD;
    put_unaligned (htonl (count), (unsigned int *) &pc->c[1]);
    pc->c[1] = cmd;
    set_bit (PC_WAIT_FOR_DSC, &pc->flags);
    pc->callback = &idetape_pc_callback;
}

/*
 * Verify that we have the correct tape frame
 */
static int idetape_verify_stage (ide_drive_t *drive, idetape_stage_t *stage, int logical_blk_num, int quiet)
{
    idetape_tape_t *tape = drive->driver_data;
    os_aux_t *aux = stage->aux;
    os_partition_t *par = &aux->partition;
    struct request *rq = &stage->rq;
    struct buffer_head *bh;

    if (!tape->onstream)
        return 1;
    if (tape->raw) {
        if (rq->errors) {
            bh = stage->bh;
            while (bh) {
                memset(bh->b_data, 0, bh->b_size);
                bh = bh->b_reqnext;
            }
            strcpy(stage->bh->b_data, "READ ERROR ON FRAME");
        }
        return 1;
    }
    if (rq->errors == IDETAPE_ERROR_GENERAL) {
        printk(KERN_INFO "ide-tape: %s: skipping frame %d, read error\n", tape->name, tape->first_frame_position);
        return 0;
    }
    if (rq->errors == IDETAPE_ERROR_EOD) {
        printk(KERN_INFO "ide-tape: %s: skipping frame %d, eod\n", tape->name, tape->first_frame_position);
        return 0;
    }
    if (ntohl(aux->format_id) != 0) {
        printk(KERN_INFO "ide-tape: %s: skipping frame %d, format_id %u\n", tape->name, tape->first_frame_position, ntohl(aux->format_id));
        return 0;
    }
    if (memcmp(aux->application_sig, tape->application_sig, 4) != 0) {
        printk(KERN_INFO "ide-tape: %s: skipping frame %d, incorrect application signature\n", tape->name, tape->first_frame_position);
        return 0;
    }
    if (aux->frame_type != OS_FRAME_TYPE_DATA &&
        aux->frame_type != OS_FRAME_TYPE_EOD &&
        aux->frame_type != OS_FRAME_TYPE_MARKER) {
        printk(KERN_INFO "ide-tape: %s: skipping frame %d, frame type %x\n", tape->name, tape->first_frame_position, aux->frame_type);
        return 0;
    }
    if (par->partition_num != OS_DATA_PARTITION) {
        if (!tape->linux_media || tape->linux_media_version != 2) {
            printk(KERN_INFO "ide-tape: %s: skipping frame %d, partition num %d\n", tape->name, tape->first_frame_position, par->partition_num);
            return 0;
        }
    }
    if (par->par_desc_ver != OS_PARTITION_VERSION) {
        printk(KERN_INFO "ide-tape: %s: skipping frame %d, partition version %d\n", tape->name, tape->first_frame_position, par->par_desc_ver);
        return 0;
    }
    if (ntohs(par->wrt_pass_cntr) != tape->wrt_pass_cntr) {
        printk(KERN_INFO "ide-tape: %s: skipping frame %d, wrt_pass_cntr %d (expected %d)(logical_blk_num %u)\n", tape->name, tape->first_frame_position, ntohs(par->wrt_pass_cntr), tape->wrt_pass_cntr, ntohl(aux->logical_blk_num));
        return 0;
    }
    if (aux->frame_seq_num != aux->logical_blk_num) {
        printk(KERN_INFO "ide-tape: %s: skipping frame %d, seq != logical\n", tape->name, tape->first_frame_position);
        return 0;
    }
    if (logical_blk_num != -1 && ntohl(aux->logical_blk_num) != logical_blk_num) {
        if (!quiet)
            printk(KERN_INFO "ide-tape: %s: skipping frame %d, logical_blk_num %u (expected %d)\n", tape->name, tape->first_frame_position, ntohl(aux->logical_blk_num), logical_blk_num);
        return 0;
    }
    if (aux->frame_type == OS_FRAME_TYPE_MARKER) {
        rq->errors = IDETAPE_ERROR_FILEMARK;
        rq->current_nr_sectors = rq->nr_sectors;
    }
    return 1;
}

static void idetape_wait_first_stage (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    unsigned long flags;

    if (tape->first_stage == NULL)
        return;
    spin_lock_irqsave(&tape->spinlock, flags);
    if (tape->active_stage == tape->first_stage)
        idetape_wait_for_request(drive, tape->active_data_request);
    spin_unlock_irqrestore(&tape->spinlock, flags);
}

/*
 *    idetape_add_chrdev_write_request tries to add a character device
 *    originated write request to our pipeline. In case we don't succeed,
 *    we revert to non-pipelined operation mode for this request.
 *
 *    1.    Try to allocate a new pipeline stage.
 *    2.    If we can't, wait for more and more requests to be serviced
 *        and try again each time.
 *    3.    If we still can't allocate a stage, fallback to
 *        non-pipelined operation mode for this request.
 */
static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *new_stage;
    unsigned long flags;
    struct request *rq;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 3)
        printk (KERN_INFO "ide-tape: Reached idetape_add_chrdev_write_request\n");
#endif /* IDETAPE_DEBUG_LOG */

         /*
          *    Attempt to allocate a new stage.
     *    Pay special attention to possible race conditions.
     */
    while ((new_stage = idetape_kmalloc_stage (tape)) == NULL) {
        spin_lock_irqsave(&tape->spinlock, flags);
        if (idetape_pipeline_active (tape)) {
            idetape_wait_for_request(drive, tape->active_data_request);
            spin_unlock_irqrestore(&tape->spinlock, flags);
        } else {
            spin_unlock_irqrestore(&tape->spinlock, flags);
            idetape_insert_pipeline_into_queue (drive);
            if (idetape_pipeline_active (tape))
                continue;
            /*
             *    Linux is short on memory. Fallback to
             *    non-pipelined operation mode for this request.
             */
            return idetape_queue_rw_tail (drive, IDETAPE_WRITE_RQ, blocks, tape->merge_stage->bh);
        }
    }
    rq = &new_stage->rq;
    ide_init_drive_cmd (rq);
    rq->cmd = IDETAPE_WRITE_RQ;
    rq->sector = tape->first_frame_position;    /* Doesn't actually matter - We always assume sequential access */
    rq->nr_sectors = rq->current_nr_sectors = blocks;

    idetape_switch_buffers (tape, new_stage);
    idetape_init_stage(drive, new_stage, OS_FRAME_TYPE_DATA, tape->logical_blk_num);
    tape->logical_blk_num++;
    idetape_add_stage_tail (drive, new_stage);
    tape->pipeline_head++;
#if USE_IOTRACE
    IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
    calculate_speeds(drive);

    /*
     *    Estimate whether the tape has stopped writing by checking
     *    if our write pipeline is currently empty. If we are not
     *    writing anymore, wait for the pipeline to be full enough
     *    (90%) before starting to service requests, so that we will
     *    be able to keep up with the higher speeds of the tape.
     *
     *    For the OnStream drive, we can query the number of pending
     *    frames in the drive's internal buffer. As long as the tape
     *    is still writing, it is better to write frames immediately
     *    rather than gather them in the pipeline. This will give the
     *    tape's firmware the ability to sense the current incoming
     *    data rate more accurately, and since the OnStream tape
     *    supports variable speeds, it can try to adjust itself to the
     *    incoming data rate.
     */
    if (!idetape_pipeline_active(tape)) {
        if (tape->nr_stages >= tape->max_stages * 9 / 10 ||
            tape->nr_stages >= tape->max_stages - tape->uncontrolled_pipeline_head_speed * 3 * 1024 / tape->tape_block_size) {
            tape->measure_insert_time = 1;
            tape->insert_time = jiffies;
            tape->insert_size = 0;
            tape->insert_speed = 0;
            idetape_insert_pipeline_into_queue (drive);
        } else if (tape->onstream) {
            idetape_update_stats(drive);
            if (tape->cur_frames > 5)
                idetape_insert_pipeline_into_queue (drive);
        }
    }
    if (test_and_clear_bit (IDETAPE_PIPELINE_ERROR, &tape->flags))        /* Return a deferred error */
        return -EIO;
    return blocks;
}

/*
 *    idetape_wait_for_pipeline will wait until all pending pipeline
 *    requests are serviced. Typically called on device close.
 */
static void idetape_wait_for_pipeline (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    unsigned long flags;

    while (tape->next_stage || idetape_pipeline_active(tape)) {
        idetape_insert_pipeline_into_queue (drive);
        spin_lock_irqsave(&tape->spinlock, flags);
        if (idetape_pipeline_active(tape))
            idetape_wait_for_request(drive, tape->active_data_request);
        spin_unlock_irqrestore(&tape->spinlock, flags);
    }
}

static void idetape_empty_write_pipeline (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    int blocks, i, min;
    struct buffer_head *bh;
    
#if IDETAPE_DEBUG_BUGS
    if (tape->chrdev_direction != idetape_direction_write) {
        printk (KERN_ERR "ide-tape: bug: Trying to empty write pipeline, but we are not writing.\n");
        return;
    }
    if (tape->merge_stage_size > tape->stage_size) {
        printk (KERN_ERR "ide-tape: bug: merge_buffer too big\n");
        tape->merge_stage_size = tape->stage_size;
    }
#endif /* IDETAPE_DEBUG_BUGS */
    if (tape->merge_stage_size) {
        blocks = tape->merge_stage_size / tape->tape_block_size;
        if (tape->merge_stage_size % tape->tape_block_size) {
            blocks++;
            i = tape->tape_block_size - tape->merge_stage_size % tape->tape_block_size;
            bh = tape->bh->b_reqnext;
            while (bh) {
                atomic_set(&bh->b_count, 0);
                bh = bh->b_reqnext;
            }
            bh = tape->bh;
            while (i) {
                if (bh == NULL) {
                    printk(KERN_INFO "ide-tape: bug, bh NULL\n");
                    break;
                }
                min = IDE_MIN(i, bh->b_size - atomic_read(&bh->b_count));
                memset(bh->b_data + atomic_read(&bh->b_count), 0, min);
                atomic_add(min, &bh->b_count);
                i -= min;
                bh = bh->b_reqnext;
            }
        }
        (void) idetape_add_chrdev_write_request (drive, blocks);
        tape->merge_stage_size = 0;
    }
    idetape_wait_for_pipeline (drive);
    if (tape->merge_stage != NULL) {
        __idetape_kfree_stage (tape->merge_stage);
        tape->merge_stage = NULL;
    }
    clear_bit (IDETAPE_PIPELINE_ERROR, &tape->flags);
    tape->chrdev_direction = idetape_direction_none;

    /*
     *    On the next backup, perform the feedback loop again.
     *    (I don't want to keep sense information between backups,
     *     as some systems are constantly on, and the system load
     *     can be totally different on the next backup).
     */
    tape->max_stages = tape->min_pipeline;
#if IDETAPE_DEBUG_BUGS
    if (tape->first_stage != NULL || tape->next_stage != NULL || tape->last_stage != NULL || tape->nr_stages != 0) {
        printk (KERN_ERR "ide-tape: ide-tape pipeline bug, "
        "first_stage %p, next_stage %p, last_stage %p, nr_stages %d\n",
        tape->first_stage, tape->next_stage, tape->last_stage, tape->nr_stages);
    }
#endif /* IDETAPE_DEBUG_BUGS */
}

static void idetape_restart_speed_control (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

    tape->restart_speed_control_req = 0;
    tape->pipeline_head = 0;
    tape->buffer_head = tape->tape_head = tape->cur_frames;
    tape->controlled_last_pipeline_head = tape->uncontrolled_last_pipeline_head = 0;
    tape->controlled_previous_pipeline_head = tape->uncontrolled_previous_pipeline_head = 0;
    tape->pipeline_head_speed = tape->controlled_pipeline_head_speed = 5000;
    tape->uncontrolled_pipeline_head_speed = 0;
    tape->controlled_pipeline_head_time = tape->uncontrolled_pipeline_head_time = jiffies;
    tape->controlled_previous_head_time = tape->uncontrolled_previous_head_time = jiffies;
}

static int idetape_initiate_read (ide_drive_t *drive, int max_stages)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *new_stage;
    struct request rq;
    int bytes_read;
    int blocks = tape->capabilities.ctl;

    if (tape->chrdev_direction != idetape_direction_read) {        /* Initialize read operation */
        if (tape->chrdev_direction == idetape_direction_write) {
            idetape_empty_write_pipeline (drive);
            idetape_flush_tape_buffers (drive);
        }
#if IDETAPE_DEBUG_BUGS
        if (tape->merge_stage || tape->merge_stage_size) {
            printk (KERN_ERR "ide-tape: merge_stage_size should be 0 now\n");
            tape->merge_stage_size = 0;
        }
#endif /* IDETAPE_DEBUG_BUGS */
        if ((tape->merge_stage = __idetape_kmalloc_stage (tape, 0, 0)) == NULL)
            return -ENOMEM;
        tape->chrdev_direction = idetape_direction_read;
        tape->logical_blk_num = 0;

        /*
         *    Issue a read 0 command to ensure that DSC handshake
         *    is switched from completion mode to buffer available
         *    mode.
         */
        bytes_read = idetape_queue_rw_tail (drive, IDETAPE_READ_RQ, 0, tape->merge_stage->bh);
        if (bytes_read < 0) {
            kfree (tape->merge_stage);
            tape->merge_stage = NULL;
            tape->chrdev_direction = idetape_direction_none;
            return bytes_read;
        }
    }
    if (tape->restart_speed_control_req)
        idetape_restart_speed_control(drive);
    ide_init_drive_cmd (&rq);
    rq.cmd = IDETAPE_READ_RQ;
    rq.sector = tape->first_frame_position;
    rq.nr_sectors = rq.current_nr_sectors = blocks;
    if (!test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags) && tape->nr_stages <= max_stages) {
        new_stage = idetape_kmalloc_stage (tape);
        while (new_stage != NULL) {
            new_stage->rq = rq;
            idetape_add_stage_tail (drive, new_stage);
            if (tape->nr_stages >= max_stages)
                break;
            new_stage = idetape_kmalloc_stage (tape);
        }
    }
    if (!idetape_pipeline_active(tape)) {
        if (tape->nr_pending_stages >= 3 * max_stages / 4) {
            tape->measure_insert_time = 1;
            tape->insert_time = jiffies;
            tape->insert_size = 0;
            tape->insert_speed = 0;
            idetape_insert_pipeline_into_queue (drive);
        } else if (tape->onstream) {
            idetape_update_stats(drive);
            if (tape->cur_frames < tape->max_frames - 5)
                idetape_insert_pipeline_into_queue (drive);
        }
    }
    return 0;
}

static int idetape_get_logical_blk (ide_drive_t *drive, int logical_blk_num, int max_stages, int quiet)
{
    idetape_tape_t *tape = drive->driver_data;
    unsigned long flags;
    int cnt = 0, x, position;

    /*
     * Search and wait for the next logical tape block
     */
    while (1) {
        if (cnt++ > 1000) {   /* AJN: was 100 */
            printk(KERN_INFO "ide-tape: %s: couldn't find logical block %d, aborting\n", tape->name, logical_blk_num);
            return 0;
        }
        idetape_initiate_read(drive, max_stages);
        if (tape->first_stage == NULL) {
            if (tape->onstream) {
#if ONSTREAM_DEBUG
                if (tape->debug_level >= 1)
                    printk(KERN_INFO "ide-tape: %s: first_stage == NULL, pipeline error %ld\n", tape->name, (long)test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags));
#endif
                clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
                position = idetape_read_position(drive);
                printk(KERN_INFO "ide-tape: %s: blank block detected at %d\n", tape->name, position);
                if (position >= 3000 && position < 3080)
                    position += 32;  /* Why is this check and number ??? MM */
                if (position >= OS_DATA_ENDFRAME1 && position < 3000)
                    position = 3000;
                else
                    /*
                     * compensate for write errors that generally skip 80 frames,
                     * expect around 20 read errors in a row...
                     */
                    position += 60;
                if (position >= OS_DATA_ENDFRAME1 && position < 3000)
                    position = 3000;
                printk(KERN_INFO "ide-tape: %s: positioning tape to block %d\n", tape->name, position);
                if (position == 3000)  /* seems to be needed to correctly position at block 3000 MM */
                    idetape_position_tape(drive, 0, 0, 0);
                idetape_position_tape(drive, position, 0, 0);
                cnt += 40;
                continue;
            } else
                return 0;
        }
        idetape_wait_first_stage(drive);
        if (idetape_verify_stage(drive, tape->first_stage, logical_blk_num, quiet))
            break;
        if (tape->first_stage->rq.errors == IDETAPE_ERROR_EOD)
            cnt--;
        if (idetape_verify_stage(drive, tape->first_stage, -1, quiet)) {
            x = ntohl(tape->first_stage->aux->logical_blk_num);
            if (x > logical_blk_num) {
                printk(KERN_ERR "ide-tape: %s: couldn't find logical block %d, aborting (block %d found)\n", tape->name, logical_blk_num, x);
                return 0;
            }
        }
        spin_lock_irqsave(&tape->spinlock, flags);
        idetape_remove_stage_head(drive);
        spin_unlock_irqrestore(&tape->spinlock, flags);
    }
    if (tape->onstream)
        tape->logical_blk_num = ntohl(tape->first_stage->aux->logical_blk_num);
    return 1;
}

/*
 *    idetape_add_chrdev_read_request is called from idetape_chrdev_read
 *    to service a character device read request and add read-ahead
 *    requests to our pipeline.
 */
static int idetape_add_chrdev_read_request (ide_drive_t *drive,int blocks)
{
    idetape_tape_t *tape = drive->driver_data;
    unsigned long flags;
    struct request *rq_ptr;
    int bytes_read;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_add_chrdev_read_request, %d blocks\n", blocks);
#endif /* IDETAPE_DEBUG_LOG */

    /*
     * Wait for the next logical block to be available at the head
     * of the pipeline
     */
    if (!idetape_get_logical_blk(drive, tape->logical_blk_num, tape->max_stages, 0)) {
        if (tape->onstream) {
            set_bit(IDETAPE_READ_ERROR, &tape->flags);
            return 0;
        }
        if (test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
             return 0;
        return idetape_queue_rw_tail (drive, IDETAPE_READ_RQ, blocks, tape->merge_stage->bh);
    }
    rq_ptr = &tape->first_stage->rq;
    bytes_read = tape->tape_block_size * (rq_ptr->nr_sectors - rq_ptr->current_nr_sectors);
    rq_ptr->nr_sectors = rq_ptr->current_nr_sectors = 0;


    if (tape->onstream && !tape->raw && tape->first_stage->aux->frame_type == OS_FRAME_TYPE_EOD) {
#if ONSTREAM_DEBUG
        if (tape->debug_level >= 2)
            printk(KERN_INFO "ide-tape: %s: EOD reached\n", tape->name);
#endif
        return 0;
    }
    if (rq_ptr->errors == IDETAPE_ERROR_EOD)
        return 0;
    if (rq_ptr->errors == IDETAPE_ERROR_FILEMARK) {
        idetape_switch_buffers (tape, tape->first_stage);
        set_bit (IDETAPE_FILEMARK, &tape->flags);
#if USE_IOTRACE
        IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
        calculate_speeds(drive);
    } else {
        idetape_switch_buffers (tape, tape->first_stage);
        if (rq_ptr->errors == IDETAPE_ERROR_GENERAL) {
#if ONSTREAM_DEBUG
            if (tape->debug_level >= 1)
                printk(KERN_INFO "ide-tape: error detected, bytes_read %d\n", bytes_read);
#endif
        }
        clear_bit (IDETAPE_FILEMARK, &tape->flags);
        spin_lock_irqsave(&tape->spinlock, flags);
        idetape_remove_stage_head (drive);
        spin_unlock_irqrestore(&tape->spinlock, flags);
        tape->logical_blk_num++;
        tape->pipeline_head++;
#if USE_IOTRACE
        IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
        calculate_speeds(drive);
    }
#if IDETAPE_DEBUG_BUGS
    if (bytes_read > blocks*tape->tape_block_size) {
        printk (KERN_ERR "ide-tape: bug: trying to return more bytes than requested\n");
        bytes_read=blocks*tape->tape_block_size;
    }
#endif /* IDETAPE_DEBUG_BUGS */
    return (bytes_read);
}

static void idetape_pad_zeros (ide_drive_t *drive, int bcount)
{
    idetape_tape_t *tape = drive->driver_data;
    struct buffer_head *bh;
    int count, blocks;
    
    while (bcount) {
        bh = tape->merge_stage->bh;
        count = IDE_MIN (tape->stage_size, bcount);
        bcount -= count;
        blocks = count / tape->tape_block_size;
        while (count) {
            atomic_set(&bh->b_count, IDE_MIN (count, bh->b_size));
            memset (bh->b_data, 0, atomic_read(&bh->b_count));
            count -= atomic_read(&bh->b_count);
            bh = bh->b_reqnext;
        }
        idetape_queue_rw_tail (drive, IDETAPE_WRITE_RQ, blocks, tape->merge_stage->bh);
    }
}

static int idetape_pipeline_size (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *stage;
    struct request *rq;
    int size = 0;

    idetape_wait_for_pipeline (drive);
    stage = tape->first_stage;
    while (stage != NULL) {
        rq = &stage->rq;
        size += tape->tape_block_size * (rq->nr_sectors-rq->current_nr_sectors);
        if (rq->errors == IDETAPE_ERROR_FILEMARK)
            size += tape->tape_block_size;
        stage = stage->next;
    }
    size += tape->merge_stage_size;
    return size;
}

/*
 *    Rewinds the tape to the Beginning Of the current Partition (BOP).
 *
 *    We currently support only one partition.
 */ 
static int idetape_rewind_tape (ide_drive_t *drive)
{
    int retval;
    idetape_pc_t pc;
    idetape_tape_t *tape = drive->driver_data;
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 2)
        printk (KERN_INFO "ide-tape: Reached idetape_rewind_tape\n");
#endif /* IDETAPE_DEBUG_LOG */    
    
    idetape_create_rewind_cmd (drive, &pc);
    retval = idetape_queue_pc_tail (drive, &pc);
    if (retval)
        return retval;

    idetape_create_read_position_cmd (&pc);
    retval = idetape_queue_pc_tail (drive, &pc);
    if (retval)
        return retval;
    tape->logical_blk_num = 0;
    return 0;
}

/*
 *    Our special ide-tape ioctl's.
 *
 *    Currently there aren't any ioctl's.
 *    mtio.h compatible commands should be issued to the character device
 *    interface.
 */
static int idetape_blkdev_ioctl (ide_drive_t *drive, struct inode *inode, struct file *file,
                 unsigned int cmd, unsigned long arg)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_config_t config;

#if IDETAPE_DEBUG_LOG    
    if (tape->debug_level >= 4)
        printk (KERN_INFO "ide-tape: Reached idetape_blkdev_ioctl\n");
#endif /* IDETAPE_DEBUG_LOG */
    switch (cmd) {
        case 0x0340:
            if (copy_from_user ((char *) &config, (char *) arg, sizeof (idetape_config_t)))
                return -EFAULT;
            tape->best_dsc_rw_frequency = config.dsc_rw_frequency;
            tape->max_stages = config.nr_stages;
            break;
        case 0x0350:
            config.dsc_rw_frequency = (int) tape->best_dsc_rw_frequency;
            config.nr_stages = tape->max_stages; 
            if (copy_to_user ((char *) arg, (char *) &config, sizeof (idetape_config_t)))
                return -EFAULT;
            break;
        default:
            return -EIO;
    }
    return 0;
}

/*
 *    The block device interface should not be used for data transfers.
 *    However, we still allow opening it so that we can issue general
 *    ide driver configuration ioctl's, such as the interrupt unmask feature.
 */
static int idetape_blkdev_open (struct inode *inode, struct file *filp, ide_drive_t *drive)
{
    MOD_INC_USE_COUNT;
#if ONSTREAM_DEBUG
        printk(KERN_INFO "ide-tape: MOD_INC_USE_COUNT in idetape_blkdev_open\n");
#endif
    return 0;
}

static void idetape_blkdev_release (struct inode *inode, struct file *filp, ide_drive_t *drive)
{
    MOD_DEC_USE_COUNT;
#if ONSTREAM_DEBUG
        printk(KERN_INFO "ide-tape: MOD_DEC_USE_COUNT in idetape_blkdev_release\n");
#endif
}

/*
 *    idetape_pre_reset is called before an ATAPI/ATA software reset.
 */
static void idetape_pre_reset (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    if (tape != NULL)
        set_bit (IDETAPE_IGNORE_DSC, &tape->flags);
}

/*
 *    Character device interface functions
 */
static ide_drive_t *get_drive_ptr (kdev_t i_rdev)
{
    unsigned int i = MINOR(i_rdev) & ~0xc0;

    if (i >= MAX_HWIFS * MAX_DRIVES)
        return NULL;
    return (idetape_chrdevs[i].drive);
}

static int idetape_onstream_space_over_filemarks_backward (ide_drive_t *drive,short mt_op,int mt_count)
{
    idetape_tape_t *tape = drive->driver_data;
    int cnt = 0;
    int last_mark_addr;
    unsigned long flags;

    if (!idetape_get_logical_blk(drive, -1, 10, 0)) {
        printk(KERN_INFO "ide-tape: %s: couldn't get logical blk num in space_filemarks_bwd\n", tape->name);
        return -EIO;
    }
    while (cnt != mt_count) {
        last_mark_addr = ntohl(tape->first_stage->aux->last_mark_addr);
        if (last_mark_addr == -1)
            return -EIO;
#if ONSTREAM_DEBUG
        if (tape->debug_level >= 2)
            printk(KERN_INFO "ide-tape: positioning to last mark at %d\n", last_mark_addr);
#endif
        idetape_position_tape(drive, last_mark_addr, 0, 0);
        cnt++;
        if (!idetape_get_logical_blk(drive, -1, 10, 0)) {
            printk(KERN_INFO "ide-tape: %s: couldn't get logical blk num in space_filemarks\n", tape->name);
            return -EIO;
        }
        if (tape->first_stage->aux->frame_type != OS_FRAME_TYPE_MARKER) {
            printk(KERN_INFO "ide-tape: %s: expected to find marker at block %d, not found\n", tape->name, last_mark_addr);
            return -EIO;
        }
    }
    if (mt_op == MTBSFM) {
        spin_lock_irqsave(&tape->spinlock, flags);
        idetape_remove_stage_head (drive);
        tape->logical_blk_num++;
        spin_unlock_irqrestore(&tape->spinlock, flags);
    }
    return 0;
}

/*
 * ADRL 1.1 compatible "slow" space filemarks fwd version
 *
 * Just scans for the filemark sequentially.
 */
static int idetape_onstream_space_over_filemarks_forward_slow (ide_drive_t *drive,short mt_op,int mt_count)
{
    idetape_tape_t *tape = drive->driver_data;
    int cnt = 0;
    unsigned long flags;

    if (!idetape_get_logical_blk(drive, -1, 10, 0)) {
        printk(KERN_INFO "ide-tape: %s: couldn't get logical blk num in space_filemarks_fwd\n", tape->name);
        return -EIO;
    }
    while (1) {
        if (!idetape_get_logical_blk(drive, -1, 10, 0)) {
            printk(KERN_INFO "ide-tape: %s: couldn't get logical blk num in space_filemarks\n", tape->name);
            return -EIO;
        }
        if (tape->first_stage->aux->frame_type == OS_FRAME_TYPE_MARKER)
            cnt++;
        if (tape->first_stage->aux->frame_type == OS_FRAME_TYPE_EOD) {
#if ONSTREAM_DEBUG
            if (tape->debug_level >= 2)
                printk(KERN_INFO "ide-tape: %s: space_fwd: EOD reached\n", tape->name);
#endif
            return -EIO;
        }
        if (cnt == mt_count)
            break;
        spin_lock_irqsave(&tape->spinlock, flags);
        idetape_remove_stage_head (drive);
        spin_unlock_irqrestore(&tape->spinlock, flags);
    }
    if (mt_op == MTFSF) {
        spin_lock_irqsave(&tape->spinlock, flags);
        idetape_remove_stage_head (drive);
        tape->logical_blk_num++;
        spin_unlock_irqrestore(&tape->spinlock, flags);
    }
    return 0;
}


/*
 * Fast linux specific version of OnStream FSF
 */
static int idetape_onstream_space_over_filemarks_forward_fast (ide_drive_t *drive,short mt_op,int mt_count)
{
    idetape_tape_t *tape = drive->driver_data;
    int cnt = 0, next_mark_addr;
    unsigned long flags;

    if (!idetape_get_logical_blk(drive, -1, 10, 0)) {
        printk(KERN_INFO "ide-tape: %s: couldn't get logical blk num in space_filemarks_fwd\n", tape->name);
        return -EIO;
    }

    /*
     * Find nearest (usually previous) marker
     */
    while (1) {
        if (tape->first_stage->aux->frame_type == OS_FRAME_TYPE_MARKER)
            break;
        if (tape->first_stage->aux->frame_type == OS_FRAME_TYPE_EOD) {
#if ONSTREAM_DEBUG
            if (tape->debug_level >= 2)
                printk(KERN_INFO "ide-tape: %s: space_fwd: EOD reached\n", tape->name);
#endif
            return -EIO;
        }
        if (ntohl(tape->first_stage->aux->filemark_cnt) == 0) {
            if (tape->first_mark_addr == -1) {
                printk(KERN_INFO "ide-tape: %s: reverting to slow filemark space\n", tape->name);
                return idetape_onstream_space_over_filemarks_forward_slow(drive, mt_op, mt_count);
            }
            idetape_position_tape(drive, tape->first_mark_addr, 0, 0);
            if (!idetape_get_logical_blk(drive, -1, 10, 0)) {
                printk(KERN_INFO "ide-tape: %s: couldn't get logical blk num in space_filemarks_fwd_fast\n", tape->name);
                return -EIO;
            }
            if (tape->first_stage->aux->frame_type != OS_FRAME_TYPE_MARKER) {
                printk(KERN_INFO "ide-tape: %s: expected to find filemark at %d\n", tape->name, tape->first_mark_addr);
                return -EIO;
            }
        } else {
            if (idetape_onstream_space_over_filemarks_backward(drive, MTBSF, 1) < 0)
                return -EIO;
            mt_count++;
        }
    }
    cnt++;
    while (cnt != mt_count) {
        next_mark_addr = ntohl(tape->first_stage->aux->next_mark_addr);
        if (!next_mark_addr || next_mark_addr > tape->eod_frame_addr) {
            printk(KERN_INFO "ide-tape: %s: reverting to slow filemark space\n", tape->name);
            return idetape_onstream_space_over_filemarks_forward_slow(drive, mt_op, mt_count - cnt);
#if ONSTREAM_DEBUG
        } else if (tape->debug_level >= 2) {
             printk(KERN_INFO "ide-tape: positioning to next mark at %d\n", next_mark_addr);
#endif
        }
        idetape_position_tape(drive, next_mark_addr, 0, 0);
        cnt++;
        if (!idetape_get_logical_blk(drive, -1, 10, 0)) {
            printk(KERN_INFO "ide-tape: %s: couldn't get logical blk num in space_filemarks\n", tape->name);
            return -EIO;
        }
        if (tape->first_stage->aux->frame_type != OS_FRAME_TYPE_MARKER) {
            printk(KERN_INFO "ide-tape: %s: expected to find marker at block %d, not found\n", tape->name, next_mark_addr);
            return -EIO;
        }
    }
    if (mt_op == MTFSF) {
        spin_lock_irqsave(&tape->spinlock, flags);
        idetape_remove_stage_head (drive);
        tape->logical_blk_num++;
        spin_unlock_irqrestore(&tape->spinlock, flags);
    }
    return 0;
}

/*
 *    idetape_space_over_filemarks is now a bit more complicated than just
 *    passing the command to the tape since we may have crossed some
 *    filemarks during our pipelined read-ahead mode.
 *
 *    As a minor side effect, the pipeline enables us to support MTFSFM when
 *    the filemark is in our internal pipeline even if the tape doesn't
 *    support spacing over filemarks in the reverse direction.
 */
static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_count)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t pc;
    unsigned long flags;
    int retval,count=0;
    int speed_control;

    if (tape->onstream) {
        if (tape->raw)
            return -EIO;
        speed_control = tape->speed_control;
        tape->speed_control = 0;
        if (mt_op == MTFSF || mt_op == MTFSFM) {
            if (tape->linux_media)
                retval = idetape_onstream_space_over_filemarks_forward_fast(drive, mt_op, mt_count);
            else
                retval = idetape_onstream_space_over_filemarks_forward_slow(drive, mt_op, mt_count);
        } else
            retval = idetape_onstream_space_over_filemarks_backward(drive, mt_op, mt_count);
        tape->speed_control = speed_control;
        tape->restart_speed_control_req = 1;
        return retval;
    }

    if (tape->chrdev_direction == idetape_direction_read) {
        /*
         *    We have a read-ahead buffer. Scan it for crossed
         *    filemarks.
         */
        tape->merge_stage_size = 0;
        clear_bit (IDETAPE_FILEMARK, &tape->flags);
        while (tape->first_stage != NULL) {
            idetape_wait_first_stage(drive);
            if (tape->first_stage->rq.errors == IDETAPE_ERROR_FILEMARK)
                count++;
            if (count == mt_count) {
                switch (mt_op) {
                    case MTFSF:
                        spin_lock_irqsave(&tape->spinlock, flags);
                        idetape_remove_stage_head (drive);
                        spin_unlock_irqrestore(&tape->spinlock, flags);
                    case MTFSFM:
                        return (0);
                    default:
                        break;
                }
            }
            spin_lock_irqsave(&tape->spinlock, flags);
            idetape_remove_stage_head (drive);
            spin_unlock_irqrestore(&tape->spinlock, flags);
        }
        idetape_discard_read_pipeline (drive, 1);
    }

    /*
     *    The filemark was not found in our internal pipeline.
     *    Now we can issue the space command.
     */
    switch (mt_op) {
        case MTFSF:
            idetape_create_space_cmd (&pc,mt_count-count,IDETAPE_SPACE_OVER_FILEMARK);
            return (idetape_queue_pc_tail (drive, &pc));
        case MTFSFM:
            if (!tape->capabilities.sprev)
                return (-EIO);
            retval = idetape_space_over_filemarks (drive, MTFSF, mt_count-count);
            if (retval) return (retval);
            return (idetape_space_over_filemarks (drive, MTBSF, 1));
        case MTBSF:
            if (!tape->capabilities.sprev)
                return (-EIO);
            idetape_create_space_cmd (&pc,-(mt_count+count),IDETAPE_SPACE_OVER_FILEMARK);
            return (idetape_queue_pc_tail (drive, &pc));
        case MTBSFM:
            if (!tape->capabilities.sprev)
                return (-EIO);
            retval = idetape_space_over_filemarks (drive, MTBSF, mt_count+count);
            if (retval) return (retval);
            return (idetape_space_over_filemarks (drive, MTFSF, 1));
        default:
            printk (KERN_ERR "ide-tape: MTIO operation %d not supported\n",mt_op);
            return (-EIO);
    }
}


/*
 *    Our character device read / write functions.
 *
 *    The tape is optimized to maximize throughput when it is transferring
 *    an integral number of the "continuous transfer limit", which is
 *    a parameter of the specific tape (26 KB on my particular tape).
 *      (32 kB for Onstream)
 *
 *    As of version 1.3 of the driver, the character device provides an
 *    abstract continuous view of the media - any mix of block sizes (even 1
 *    byte) on the same backup/restore procedure is supported. The driver
 *    will internally convert the requests to the recommended transfer unit,
 *    so that an unmatch between the user's block size to the recommended
 *    size will only result in a (slightly) increased driver overhead, but
 *    will no longer hit performance.
 *      This is not applicable to Onstream.
 */
static ssize_t idetape_chrdev_read (struct file *file, char *buf,
                    size_t count, loff_t *ppos)
{
    struct inode *inode = file->f_dentry->d_inode;
    ide_drive_t *drive = get_drive_ptr (inode->i_rdev);
    idetape_tape_t *tape = drive->driver_data;
    ssize_t bytes_read,temp, actually_read = 0, rc;

    if (ppos != &file->f_pos) {
        /* "A request was outside the capabilities of the device." */
        return -ENXIO;
    }
    if (tape->onstream && (count != tape->tape_block_size)) {
        printk(KERN_ERR "ide-tape: %s: use %d bytes as block size (%Zd used)\n", tape->name, tape->tape_block_size, count);
        return -EINVAL;
    }
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 3)
        printk (KERN_INFO "ide-tape: Reached idetape_chrdev_read, count %Zd\n", count);
#endif /* IDETAPE_DEBUG_LOG */

    if (tape->chrdev_direction != idetape_direction_read) {
        if (test_bit (IDETAPE_DETECT_BS, &tape->flags))
            if (count > tape->tape_block_size && (count % tape->tape_block_size) == 0)
                tape->user_bs_factor = count / tape->tape_block_size;
    }
    if ((rc = idetape_initiate_read(drive, tape->max_stages)) < 0)
        return rc;
    if (count == 0)
        return (0);
    if (tape->merge_stage_size) {
        actually_read = IDE_MIN (tape->merge_stage_size, count);
        idetape_copy_stage_to_user (tape, buf, tape->merge_stage, actually_read);
        buf += actually_read;
        tape->merge_stage_size -= actually_read;
        count -= actually_read;
    }
    while (count >= tape->stage_size) {
        bytes_read = idetape_add_chrdev_read_request (drive, tape->capabilities.ctl);
        if (bytes_read <= 0)
            goto finish;
        idetape_copy_stage_to_user (tape, buf, tape->merge_stage, bytes_read);
        buf += bytes_read;
        count -= bytes_read;
        actually_read += bytes_read;
    }
    if (count) {
        bytes_read=idetape_add_chrdev_read_request (drive, tape->capabilities.ctl);
        if (bytes_read <= 0)
            goto finish;
        temp = IDE_MIN (count, bytes_read);
        idetape_copy_stage_to_user (tape, buf, tape->merge_stage, temp);
        actually_read += temp;
        tape->merge_stage_size = bytes_read-temp;
    }
finish:
    if (!actually_read && test_bit (IDETAPE_FILEMARK, &tape->flags)) {
#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 2)
            printk(KERN_INFO "ide-tape: %s: spacing over filemark\n", tape->name);
#endif
        idetape_space_over_filemarks (drive, MTFSF, 1);
        return 0;
    }
    if (tape->onstream && !actually_read && test_and_clear_bit(IDETAPE_READ_ERROR, &tape->flags)) {
        printk(KERN_ERR "ide-tape: %s: unrecovered read error on logical block number %d, skipping\n",
                    tape->name, tape->logical_blk_num);
        tape->logical_blk_num++;
        return -EIO;
    }
    return actually_read;
}

static void idetape_update_last_marker (ide_drive_t *drive, int last_mark_addr, int next_mark_addr)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *stage;
    os_aux_t *aux;
    int position;

    if (!tape->onstream || tape->raw)
        return;
    if (last_mark_addr == -1)
        return;
    stage = __idetape_kmalloc_stage(tape, 0, 0);
    if (stage == NULL)
        return;
    idetape_flush_tape_buffers(drive);
    position = idetape_read_position(drive);
#if ONSTREAM_DEBUG
    if (tape->debug_level >= 2)
        printk(KERN_INFO "ide-tape: current position (2) %d, lblk %d\n", position, tape->logical_blk_num);
    if (tape->debug_level >= 2)
        printk(KERN_INFO "ide-tape: current position (2) tape block %d\n", tape->last_frame_position);
#endif
    idetape_position_tape(drive, last_mark_addr, 0, 0);
    if (!idetape_queue_rw_tail (drive, IDETAPE_READ_RQ, 1, stage->bh)) {
        printk(KERN_INFO "ide-tape: %s: couldn't read last marker\n", tape->name);
        __idetape_kfree_stage (stage);
        idetape_position_tape(drive, position, 0, 0);
        return;
    }
    aux = stage->aux;
    if (aux->frame_type != OS_FRAME_TYPE_MARKER) {
        printk(KERN_INFO "ide-tape: %s: expected to find marker at addr %d\n", tape->name, last_mark_addr);
        __idetape_kfree_stage (stage);
        idetape_position_tape(drive, position, 0, 0);
        return;
    }
#if ONSTREAM_DEBUG
    if (tape->debug_level >= 2)
        printk(KERN_INFO "ide-tape: writing back marker\n");
#endif
    aux->next_mark_addr = htonl(next_mark_addr);
    idetape_position_tape(drive, last_mark_addr, 0, 0);
    if (!idetape_queue_rw_tail (drive, IDETAPE_WRITE_RQ, 1, stage->bh)) {
        printk(KERN_INFO "ide-tape: %s: couldn't write back marker frame at %d\n", tape->name, last_mark_addr);
        __idetape_kfree_stage (stage);
        idetape_position_tape(drive, position, 0, 0);
        return;
    }
    __idetape_kfree_stage (stage);
    idetape_flush_tape_buffers (drive);
    idetape_position_tape(drive, position, 0, 0);
    return;
}

static void idetape_write_filler (ide_drive_t *drive, int block, int cnt)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *stage;
    int rc;

    if (!tape->onstream || tape->raw)
        return;
    stage = __idetape_kmalloc_stage(tape, 1, 1);
    if (stage == NULL)
        return;
    idetape_init_stage(drive, stage, OS_FRAME_TYPE_FILL, 0);
    idetape_wait_ready(drive, 60 * 5 * HZ);
    rc = idetape_position_tape(drive, block, 0, 0);
#if ONSTREAM_DEBUG
    printk(KERN_INFO "write_filler: positioning failed it returned %d\n", rc);
#endif
    if (rc != 0) 
        return;    /* don't write fillers if we cannot position the tape. */

    strcpy(stage->bh->b_data, "Filler");
    while (cnt--) {
        if (!idetape_queue_rw_tail (drive, IDETAPE_WRITE_RQ, 1, stage->bh)) {
            printk(KERN_INFO "ide-tape: %s: write_filler: couldn't write header frame\n", tape->name);
            __idetape_kfree_stage (stage);
            return;
        }
    }
    __idetape_kfree_stage (stage);
}

static void __idetape_write_header (ide_drive_t *drive, int block, int cnt)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *stage;
    os_header_t header;

    stage = __idetape_kmalloc_stage(tape, 1, 1);
    if (stage == NULL)
        return;
    idetape_init_stage(drive, stage, OS_FRAME_TYPE_HEADER, tape->logical_blk_num);
    idetape_wait_ready(drive, 60 * 5 * HZ);
    idetape_position_tape(drive, block, 0, 0);
    memset(&header, 0, sizeof(header));
    strcpy(header.ident_str, "ADR_SEQ");
    header.major_rev = 1;
    header.minor_rev = OS_ADR_MINREV;
    header.par_num = 1;
    header.partition.partition_num = OS_DATA_PARTITION;
    header.partition.par_desc_ver = OS_PARTITION_VERSION;
    header.partition.first_frame_addr = htonl(OS_DATA_STARTFRAME1);
    header.partition.last_frame_addr = htonl(tape->capacity);
    header.partition.wrt_pass_cntr = htons(tape->wrt_pass_cntr);
    header.partition.eod_frame_addr = htonl(tape->eod_frame_addr);
    memcpy(stage->bh->b_data, &header, sizeof(header));
    while (cnt--) {
        if (!idetape_queue_rw_tail (drive, IDETAPE_WRITE_RQ, 1, stage->bh)) {
            printk(KERN_INFO "ide-tape: %s: couldn't write header frame\n", tape->name);
            __idetape_kfree_stage (stage);
            return;
        }
    }
    __idetape_kfree_stage (stage);
    idetape_flush_tape_buffers (drive);
}

static void idetape_write_header (ide_drive_t *drive, int locate_eod)
{
    idetape_tape_t *tape = drive->driver_data;

#if ONSTREAM_DEBUG
    if (tape->debug_level >= 2)
        printk(KERN_INFO "ide-tape: %s: writing tape header\n", tape->name);
#endif
    if (!tape->onstream || tape->raw)
        return;
    tape->update_frame_cntr++;
    __idetape_write_header(drive, 5, 5);
    __idetape_write_header(drive, 0xbae, 5); /* 2990 */
    if (locate_eod) {
#if ONSTREAM_DEBUG
        if (tape->debug_level >= 2)
            printk(KERN_INFO "ide-tape: %s: locating back to eod frame addr %d\n", tape->name, tape->eod_frame_addr);
#endif
        idetape_position_tape(drive, tape->eod_frame_addr, 0, 0);
    }
}

static ssize_t idetape_chrdev_write (struct file *file, const char *buf,
                     size_t count, loff_t *ppos)
{
    struct inode *inode = file->f_dentry->d_inode;
    ide_drive_t *drive = get_drive_ptr (inode->i_rdev);
    idetape_tape_t *tape = drive->driver_data;
    ssize_t retval, actually_written = 0;
    int position;

    if (ppos != &file->f_pos) {
        /* "A request was outside the capabilities of the device." */
        return -ENXIO;
    }

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 3)
        printk (KERN_INFO "ide-tape: Reached idetape_chrdev_write, count %Zd\n", count);
#endif /* IDETAPE_DEBUG_LOG */

    if (tape->onstream) {
        if (count != tape->tape_block_size) {
            printk(KERN_ERR "ide-tape: %s: chrdev_write: use %d bytes as block size (%Zd used)\n",
                    tape->name, tape->tape_block_size, count);
            return -EINVAL;
        }
        /*
         * Check if we reach the end of the tape. Just assume the whole pipeline
         * is filled with write requests!
         */
        if (tape->first_frame_position + tape->nr_stages >= tape->capacity - OS_EW)  {
#if ONSTREAM_DEBUG
            printk(KERN_INFO, "chrdev_write: Write truncated at EOM early warning");
#endif
            if (tape->chrdev_direction == idetape_direction_write)
                idetape_write_release(inode);
            return -ENOSPC;
        }
    }

    if (tape->chrdev_direction != idetape_direction_write) {    /* Initialize write operation */
        if (tape->chrdev_direction == idetape_direction_read)
            idetape_discard_read_pipeline (drive, 1);
#if IDETAPE_DEBUG_BUGS
        if (tape->merge_stage || tape->merge_stage_size) {
            printk (KERN_ERR "ide-tape: merge_stage_size should be 0 now\n");
            tape->merge_stage_size = 0;
        }
#endif /* IDETAPE_DEBUG_BUGS */
        if ((tape->merge_stage = __idetape_kmalloc_stage (tape, 0, 0)) == NULL)
            return -ENOMEM;
        tape->chrdev_direction = idetape_direction_write;
        idetape_init_merge_stage (tape);

        if (tape->onstream) {
            position = idetape_read_position(drive);
            if (position <= OS_DATA_STARTFRAME1) {
                tape->logical_blk_num = 0;
                tape->wrt_pass_cntr++;
#if ONSTREAM_DEBUG
                if (tape->debug_level >= 2)
                    printk(KERN_INFO "ide-tape: %s: logical block num 0, setting eod to %d\n", tape->name, OS_DATA_STARTFRAME1);
                if (tape->debug_level >= 2)
                    printk(KERN_INFO "ide-tape: %s: allocating new write pass counter %d\n", tape->name, tape->wrt_pass_cntr);
#endif
                tape->filemark_cnt = 0;
                tape->eod_frame_addr = OS_DATA_STARTFRAME1;
                tape->first_mark_addr = tape->last_mark_addr = -1;
                idetape_write_header(drive, 1);
            }
#if ONSTREAM_DEBUG
            if (tape->debug_level >= 2)
                printk(KERN_INFO "ide-tape: %s: positioning tape to eod at %d\n", tape->name, tape->eod_frame_addr);
#endif
            position = idetape_read_position(drive);
            if (position != tape->eod_frame_addr)
                idetape_position_tape(drive, tape->eod_frame_addr, 0, 0);
#if ONSTREAM_DEBUG
            if (tape->debug_level >= 2)
                printk(KERN_INFO "ide-tape: %s: first_frame_position %d\n", tape->name, tape->first_frame_position);
#endif
        }

        /*
         *    Issue a write 0 command to ensure that DSC handshake
         *    is switched from completion mode to buffer available
         *    mode.
         */
        retval = idetape_queue_rw_tail (drive, IDETAPE_WRITE_RQ, 0, tape->merge_stage->bh);
        if (retval < 0) {
            kfree (tape->merge_stage);
            tape->merge_stage = NULL;
            tape->chrdev_direction = idetape_direction_none;
            return retval;
        }
#if ONSTREAM_DEBUG
        if (tape->debug_level >= 2)
            printk("ide-tape: first_frame_position %d\n", tape->first_frame_position);
#endif
    }
    if (count == 0)
        return (0);
    if (tape->restart_speed_control_req)
        idetape_restart_speed_control(drive);
    if (tape->merge_stage_size) {
#if IDETAPE_DEBUG_BUGS
        if (tape->merge_stage_size >= tape->stage_size) {
            printk (KERN_ERR "ide-tape: bug: merge buffer too big\n");
            tape->merge_stage_size = 0;
        }
#endif /* IDETAPE_DEBUG_BUGS */
        actually_written = IDE_MIN (tape->stage_size - tape->merge_stage_size, count);
        idetape_copy_stage_from_user (tape, tape->merge_stage, buf, actually_written);
        buf += actually_written;
        tape->merge_stage_size += actually_written;
        count -= actually_written;

        if (tape->merge_stage_size == tape->stage_size) {
            tape->merge_stage_size = 0;
            retval = idetape_add_chrdev_write_request (drive, tape->capabilities.ctl);
            if (retval <= 0)
                return (retval);
        }
    }
    while (count >= tape->stage_size) {
        idetape_copy_stage_from_user (tape, tape->merge_stage, buf, tape->stage_size);
        buf += tape->stage_size;
        count -= tape->stage_size;
        retval = idetape_add_chrdev_write_request (drive, tape->capabilities.ctl);
        actually_written += tape->stage_size;
        if (retval <= 0)
            return (retval);
    }
    if (count) {
        actually_written+=count;
        idetape_copy_stage_from_user (tape, tape->merge_stage, buf, count);
        tape->merge_stage_size += count;
    }
    return (actually_written);
}

static int idetape_write_filemark (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    int last_mark_addr;
    idetape_pc_t pc;

    if (!tape->onstream) {
        idetape_create_write_filemark_cmd(drive, &pc, 1);    /* Write a filemark */
        if (idetape_queue_pc_tail (drive, &pc)) {
            printk (KERN_ERR "ide-tape: Couldn't write a filemark\n");
            return -EIO;
        }
    } else if (!tape->raw) {
        last_mark_addr = idetape_read_position(drive);
        tape->merge_stage = __idetape_kmalloc_stage (tape, 1, 0);
        if (tape->merge_stage != NULL) {
            idetape_init_stage(drive, tape->merge_stage, OS_FRAME_TYPE_MARKER, tape->logical_blk_num);
            idetape_pad_zeros (drive, tape->stage_size);
            tape->logical_blk_num++;
            __idetape_kfree_stage (tape->merge_stage);
            tape->merge_stage = NULL;
        }
        if (tape->filemark_cnt)
            idetape_update_last_marker(drive, tape->last_mark_addr, last_mark_addr);
        tape->last_mark_addr = last_mark_addr;
        if (tape->filemark_cnt++ == 0)
            tape->first_mark_addr = last_mark_addr;
    }
    return 0;
}

static void idetape_write_eod (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

    if (!tape->onstream || tape->raw)
        return;
    tape->merge_stage = __idetape_kmalloc_stage (tape, 1, 0);
    if (tape->merge_stage != NULL) {
        tape->eod_frame_addr = idetape_read_position(drive);
        idetape_init_stage(drive, tape->merge_stage, OS_FRAME_TYPE_EOD, tape->logical_blk_num);
        idetape_pad_zeros (drive, tape->stage_size);
        __idetape_kfree_stage (tape->merge_stage);
        tape->merge_stage = NULL;
    }
    return;
}

int idetape_seek_logical_blk (ide_drive_t *drive, int logical_blk_num)
{
    idetape_tape_t *tape = drive->driver_data;
    int estimated_address = logical_blk_num + 20;
    int retries = 0;
    int speed_control;

    speed_control = tape->speed_control;
    tape->speed_control = 0;
    if (logical_blk_num < 0)
        logical_blk_num = 0;
    if (idetape_get_logical_blk(drive, logical_blk_num, 10, 1))
        goto ok;
    while (++retries < 10) {
        idetape_discard_read_pipeline(drive, 0);
        idetape_position_tape(drive, estimated_address, 0, 0);
        if (idetape_get_logical_blk(drive, logical_blk_num, 10, 1))
            goto ok;
        if (!idetape_get_logical_blk(drive, -1, 10, 1))
            goto error;
        if (tape->logical_blk_num < logical_blk_num)
            estimated_address += logical_blk_num - tape->logical_blk_num;
        else
            break;
    }
error:
    tape->speed_control = speed_control;
    tape->restart_speed_control_req = 1;
    printk(KERN_INFO "ide-tape: %s: couldn't seek to logical block %d (at %d), %d retries\n", tape->name, logical_blk_num, tape->logical_blk_num, retries);
    return -EIO;
ok:
    tape->speed_control = speed_control;
    tape->restart_speed_control_req = 1;
    return 0;
}

/*
 *    idetape_mtioctop is called from idetape_chrdev_ioctl when
 *    the general mtio MTIOCTOP ioctl is requested.
 *
 *    We currently support the following mtio.h operations:
 *
 *    MTFSF    -    Space over mt_count filemarks in the positive direction.
 *            The tape is positioned after the last spaced filemark.
 *
 *    MTFSFM    -    Same as MTFSF, but the tape is positioned before the
 *            last filemark.
 *
 *    MTBSF    -    Steps background over mt_count filemarks, tape is
 *            positioned before the last filemark.
 *
 *    MTBSFM    -    Like MTBSF, only tape is positioned after the last filemark.
 *
 *    Note:
 *
 *        MTBSF and MTBSFM are not supported when the tape doesn't
 *        supports spacing over filemarks in the reverse direction.
 *        In this case, MTFSFM is also usually not supported (it is
 *        supported in the rare case in which we crossed the filemark
 *        during our read-ahead pipelined operation mode).
 *        
 *    MTWEOF    -    Writes mt_count filemarks. Tape is positioned after
 *            the last written filemark.
 *
 *    MTREW    -    Rewinds tape.
 *
 *    MTLOAD    -    Loads the tape.
 *
 *    MTOFFL    -    Puts the tape drive "Offline": Rewinds the tape and
 *    MTUNLOAD    prevents further access until the media is replaced.
 *
 *    MTNOP    -    Flushes tape buffers.
 *
 *    MTRETEN    -    Retension media. This typically consists of one end
 *            to end pass on the media.
 *
 *    MTEOM    -    Moves to the end of recorded data.
 *
 *    MTERASE    -    Erases tape.
 *
 *    MTSETBLK -     Sets the user block size to mt_count bytes. If
 *            mt_count is 0, we will attempt to autodetect
 *            the block size.
 *
 *    MTSEEK    -    Positions the tape in a specific block number, where
 *            each block is assumed to contain which user_block_size
 *            bytes.
 *
 *    MTSETPART -     Switches to another tape partition.
 *
 *    MTLOCK -     Locks the tape door.
 *
 *    MTUNLOCK -     Unlocks the tape door.
 *
 *    The following commands are currently not supported:
 *
 *    MTFSS, MTBSS, MTWSM, MTSETDENSITY,
 *    MTSETDRVBUFFER, MT_ST_BOOLEANS, MT_ST_WRITE_THRESHOLD.
 */
static int idetape_mtioctop (ide_drive_t *drive,short mt_op,int mt_count)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t pc;
    int i,retval;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 1)
        printk (KERN_INFO "ide-tape: Handling MTIOCTOP ioctl: mt_op=%d, mt_count=%d\n",mt_op,mt_count);
#endif /* IDETAPE_DEBUG_LOG */
    /*
     *    Commands which need our pipelined read-ahead stages.
     */
    switch (mt_op) {
        case MTFSF:
        case MTFSFM:
        case MTBSF:
        case MTBSFM:
            if (!mt_count)
                return (0);
            return (idetape_space_over_filemarks (drive,mt_op,mt_count));
        default:
            break;
    }
    switch (mt_op) {
        case MTWEOF:
            idetape_discard_read_pipeline (drive, 1);
            for (i = 0; i < mt_count; i++) {
                retval = idetape_write_filemark(drive);
                if (retval) return retval;
            }
            return (0);
        case MTREW:
            idetape_discard_read_pipeline (drive, 0);
            if (idetape_rewind_tape(drive))
                return -EIO;
            if (tape->onstream && !tape->raw)
                return idetape_position_tape(drive, OS_DATA_STARTFRAME1, 0, 0);
            return 0;
        case MTLOAD:
            idetape_discard_read_pipeline (drive, 0);
            idetape_create_load_unload_cmd (drive, &pc, IDETAPE_LU_LOAD_MASK);
            return (idetape_queue_pc_tail (drive, &pc));
        case MTUNLOAD:
        case MTOFFL:
            idetape_discard_read_pipeline (drive, 0);
            idetape_create_load_unload_cmd (drive, &pc,!IDETAPE_LU_LOAD_MASK);
            return (idetape_queue_pc_tail (drive, &pc));
        case MTNOP:
            idetape_discard_read_pipeline (drive, 0);
            return (idetape_flush_tape_buffers (drive));
        case MTRETEN:
            idetape_discard_read_pipeline (drive, 0);
            idetape_create_load_unload_cmd (drive, &pc,IDETAPE_LU_RETENSION_MASK | IDETAPE_LU_LOAD_MASK);
            return (idetape_queue_pc_tail (drive, &pc));
        case MTEOM:
            if (tape->onstream) {
#if ONSTREAM_DEBUG
                if (tape->debug_level >= 2)
                    printk(KERN_INFO "ide-tape: %s: positioning tape to eod at %d\n", tape->name, tape->eod_frame_addr);
#endif
                idetape_position_tape(drive, tape->eod_frame_addr, 0, 0);
                if (!idetape_get_logical_blk(drive, -1, 10, 0))
                    return -EIO;
                if (tape->first_stage->aux->frame_type != OS_FRAME_TYPE_EOD)
                    return -EIO;
                return 0;
            }
            idetape_create_space_cmd (&pc, 0, IDETAPE_SPACE_TO_EOD);
            return (idetape_queue_pc_tail (drive, &pc));
        case MTERASE:
            if (tape->onstream) {
                tape->eod_frame_addr = OS_DATA_STARTFRAME1;
                tape->logical_blk_num = 0;
                tape->first_mark_addr = tape->last_mark_addr = -1;
                idetape_position_tape(drive, tape->eod_frame_addr, 0, 0);
                idetape_write_eod(drive);
                idetape_flush_tape_buffers (drive);
                idetape_write_header(drive, 0);
                /*
                 * write filler frames to the unused frames...
                 * REMOVE WHEN going to LIN4 application type...
                 */
                idetape_write_filler(drive, OS_DATA_STARTFRAME1 - 10, 10);
                idetape_write_filler(drive, OS_DATA_ENDFRAME1, 10);
                idetape_flush_tape_buffers (drive);
                (void) idetape_rewind_tape (drive);
                return 0;
            }
            (void) idetape_rewind_tape (drive);
            idetape_create_erase_cmd (&pc);
            return (idetape_queue_pc_tail (drive, &pc));
        case MTSETBLK:
            if (tape->onstream) {
                if (mt_count != tape->tape_block_size) {
                    printk(KERN_INFO "ide-tape: %s: MTSETBLK %d -- only %d bytes block size supported\n", tape->name, mt_count, tape->tape_block_size);
                    return -EINVAL;
                }
                return 0;
            }
            if (mt_count) {
                if (mt_count < tape->tape_block_size || mt_count % tape->tape_block_size)
                    return -EIO;
                tape->user_bs_factor = mt_count / tape->tape_block_size;
                clear_bit (IDETAPE_DETECT_BS, &tape->flags);
            } else
                set_bit (IDETAPE_DETECT_BS, &tape->flags);
            return 0;
        case MTSEEK:
            if (!tape->onstream || tape->raw) {
                idetape_discard_read_pipeline (drive, 0);
                return idetape_position_tape (drive, mt_count * tape->user_bs_factor, tape->partition, 0);
            }
            return idetape_seek_logical_blk(drive, mt_count);
        case MTSETPART:
            idetape_discard_read_pipeline (drive, 0);
            if (tape->onstream)
                return -EIO;
            return (idetape_position_tape (drive, 0, mt_count, 0));
        case MTFSR:
        case MTBSR:
            if (tape->onstream) {
                if (!idetape_get_logical_blk(drive, -1, 10, 0))
                    return -EIO;
                if (mt_op == MTFSR)
                    return idetape_seek_logical_blk(drive, tape->logical_blk_num + mt_count);
                else {
                    idetape_discard_read_pipeline (drive, 0);
                    return idetape_seek_logical_blk(drive, tape->logical_blk_num - mt_count);
                }
            }
        case MTLOCK:
            if (!idetape_create_prevent_cmd(drive, &pc, 1))
                return 0;
            retval = idetape_queue_pc_tail (drive, &pc);
            if (retval) return retval;
            tape->door_locked = DOOR_EXPLICITLY_LOCKED;
            return 0;
        case MTUNLOCK:
            if (!idetape_create_prevent_cmd(drive, &pc, 0))
                return 0;
            retval = idetape_queue_pc_tail (drive, &pc);
            if (retval) return retval;
            tape->door_locked = DOOR_UNLOCKED;
            return 0;
        default:
            printk (KERN_ERR "ide-tape: MTIO operation %d not supported\n",mt_op);
            return (-EIO);
    }
}

/*
 *    Our character device ioctls.
 *
 *    General mtio.h magnetic io commands are supported here, and not in
 *    the corresponding block interface.
 *
 *    The following ioctls are supported:
 *
 *    MTIOCTOP -    Refer to idetape_mtioctop for detailed description.
 *
 *    MTIOCGET -     The mt_dsreg field in the returned mtget structure
 *            will be set to (user block size in bytes <<
 *            MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK.
 *
 *            The mt_blkno is set to the current user block number.
 *            The other mtget fields are not supported.
 *
 *    MTIOCPOS -    The current tape "block position" is returned. We
 *            assume that each block contains user_block_size
 *            bytes.
 *
 *    Our own ide-tape ioctls are supported on both interfaces.
 */
static int idetape_chrdev_ioctl (struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
    ide_drive_t *drive = get_drive_ptr (inode->i_rdev);
    idetape_tape_t *tape = drive->driver_data;
    struct mtop mtop;
    struct mtget mtget;
    struct mtpos mtpos;
    int block_offset = 0, position = tape->first_frame_position;

#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 3)
        printk (KERN_INFO "ide-tape: Reached idetape_chrdev_ioctl, cmd=%u\n",cmd);
#endif /* IDETAPE_DEBUG_LOG */

    tape->restart_speed_control_req = 1;
    if (tape->chrdev_direction == idetape_direction_write) {
        idetape_empty_write_pipeline (drive);
        idetape_flush_tape_buffers (drive);
    }
    if (cmd == MTIOCGET || cmd == MTIOCPOS) {
        block_offset = idetape_pipeline_size (drive) / (tape->tape_block_size * tape->user_bs_factor);
        if ((position = idetape_read_position(drive)) < 0)
            return -EIO;
    }
    switch (cmd) {
        case MTIOCTOP:
            if (copy_from_user ((char *) &mtop, (char *) arg, sizeof (struct mtop)))
                return -EFAULT;
            return (idetape_mtioctop (drive,mtop.mt_op,mtop.mt_count));
        case MTIOCGET:
            memset (&mtget, 0, sizeof (struct mtget));
            mtget.mt_type = MT_ISSCSI2;
            if (!tape->onstream || tape->raw)
                mtget.mt_blkno = position / tape->user_bs_factor - block_offset;
            else {
                if (!idetape_get_logical_blk(drive, -1, 10, 0))
                    mtget.mt_blkno = -1;
                else
                    mtget.mt_blkno = tape->logical_blk_num;
            }
            mtget.mt_dsreg = ((tape->tape_block_size * tape->user_bs_factor) << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK;
            if (tape->onstream) {
                mtget.mt_gstat |= GMT_ONLINE(0xffffffff);
                if (tape->first_stage && tape->first_stage->aux->frame_type == OS_FRAME_TYPE_EOD)
                    mtget.mt_gstat |= GMT_EOD(0xffffffff);
                if (position <= OS_DATA_STARTFRAME1)
                    mtget.mt_gstat |= GMT_BOT(0xffffffff);
            }
            if (copy_to_user ((char *) arg,(char *) &mtget, sizeof (struct mtget)))
                return -EFAULT;
            return 0;
        case MTIOCPOS:
            if (tape->onstream && !tape->raw) {
                if (!idetape_get_logical_blk(drive, -1, 10, 0))
                    return -EIO;
                mtpos.mt_blkno = tape->logical_blk_num;
            } else
                mtpos.mt_blkno = position / tape->user_bs_factor - block_offset;
            if (copy_to_user ((char *) arg,(char *) &mtpos, sizeof (struct mtpos)))
                return -EFAULT;
            return 0;
        default:
            if (tape->chrdev_direction == idetape_direction_read)
                idetape_discard_read_pipeline (drive, 1);
            return (idetape_blkdev_ioctl (drive,inode,file,cmd,arg));
    }
}

static int __idetape_analyze_headers (ide_drive_t *drive, int block)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_stage_t *stage;
    os_header_t *header;
    os_aux_t *aux;

    if (!tape->onstream || tape->raw) {
        tape->header_ok = tape->linux_media = 1;
        return 1;
    }
    tape->header_ok = tape->linux_media = 0;
    tape->update_frame_cntr = 0;
    tape->wrt_pass_cntr = 0;
    tape->eod_frame_addr = OS_DATA_STARTFRAME1;
    tape->first_mark_addr = tape->last_mark_addr = -1;
    stage = __idetape_kmalloc_stage (tape, 0, 0);
    if (stage == NULL)
        return 0;
#if ONSTREAM_DEBUG
    if (tape->debug_level >= 2)
        printk(KERN_INFO "ide-tape: %s: reading header\n", tape->name);
#endif
    idetape_position_tape(drive, block, 0, 0);
    if (!idetape_queue_rw_tail (drive, IDETAPE_READ_RQ, 1, stage->bh)) {
        printk(KERN_INFO "ide-tape: %s: couldn't read header frame\n", tape->name);
        __idetape_kfree_stage (stage);
        return 0;
    }
    header = (os_header_t *) stage->bh->b_data;
    aux = stage->aux;
    if (strncmp(header->ident_str, "ADR_SEQ", 7) != 0) {
        printk(KERN_INFO "ide-tape: %s: invalid header identification string\n", tape->name);
        __idetape_kfree_stage (stage);
        return 0;
    }
    if (header->major_rev != 1 || (header->minor_rev > OS_ADR_MINREV))
        printk(KERN_INFO "ide-tape: warning: revision %d.%d detected (up to 1.%d supported)\n", header->major_rev, header->minor_rev, OS_ADR_MINREV);
    if (header->par_num != 1)
        printk(KERN_INFO "ide-tape: warning: %d partitions defined, only one supported\n", header->par_num);
    tape->wrt_pass_cntr = ntohs(header->partition.wrt_pass_cntr);
    tape->eod_frame_addr = ntohl(header->partition.eod_frame_addr);
    tape->filemark_cnt = ntohl(aux->filemark_cnt);
    tape->first_mark_addr = ntohl(aux->next_mark_addr);
    tape->last_mark_addr = ntohl(aux->last_mark_addr);
    tape->update_frame_cntr = ntohl(aux->update_frame_cntr);
    memcpy(tape->application_sig, aux->application_sig, 4);
    tape->application_sig[4] = 0;
    if (memcmp(tape->application_sig, "LIN", 3) == 0) {
        tape->linux_media = 1;
        tape->linux_media_version = tape->application_sig[3] - '0';
        if (tape->linux_media_version != 3)
            printk(KERN_INFO "ide-tape: %s: Linux media version %d detected (current 3)\n",
                     tape->name, tape->linux_media_version);
    } else {
        printk(KERN_INFO "ide-tape: %s: non Linux media detected (%s)\n", tape->name, tape->application_sig);
        tape->linux_media = 0;
    }
#if ONSTREAM_DEBUG
    if (tape->debug_level >= 2)
        printk(KERN_INFO "ide-tape: %s: detected write pass counter %d, eod frame addr %d\n", tape->name, tape->wrt_pass_cntr, tape->eod_frame_addr);
#endif
    __idetape_kfree_stage (stage);
    return 1;
}

static int idetape_analyze_headers (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    int position, block;

    if (!tape->onstream || tape->raw) {
        tape->header_ok = tape->linux_media = 1;
        return 1;
    }
    tape->header_ok = tape->linux_media = 0;
    position = idetape_read_position(drive);
    for (block = 5; block < 10; block++)
        if (__idetape_analyze_headers(drive, block))
            goto ok;
    for (block = 0xbae; block < 0xbb3; block++) /* 2990 - 2994 */
        if (__idetape_analyze_headers(drive, block))
            goto ok;
    printk(KERN_ERR "ide-tape: %s: failed to find valid ADRL header\n", tape->name);
    return 0;
ok:
    if (position < OS_DATA_STARTFRAME1)
        position = OS_DATA_STARTFRAME1;
    idetape_position_tape(drive, position, 0, 0);
    tape->header_ok = 1;
    return 1;
}

/*
 *    Our character device open function.
 */
static int idetape_chrdev_open (struct inode *inode, struct file *filp)
{
    ide_drive_t *drive;
    idetape_tape_t *tape;
    idetape_pc_t pc;
    unsigned int minor=MINOR (inode->i_rdev);
            
#if IDETAPE_DEBUG_LOG
    printk (KERN_INFO "ide-tape: Reached idetape_chrdev_open\n");
#endif /* IDETAPE_DEBUG_LOG */
    
    if ((drive = get_drive_ptr (inode->i_rdev)) == NULL)
        return -ENXIO;
    tape = drive->driver_data;

    if (test_and_set_bit (IDETAPE_BUSY, &tape->flags))
        return -EBUSY;
    MOD_INC_USE_COUNT;
    if (!tape->onstream) {    
        idetape_read_position(drive);
        if (!test_bit (IDETAPE_ADDRESS_VALID, &tape->flags))
            (void) idetape_rewind_tape (drive);
    } else {
        if (minor & 64) {
            tape->tape_block_size = tape->stage_size = 32768 + 512;
            tape->raw = 1;
        } else {
            tape->tape_block_size = tape->stage_size = 32768;
            tape->raw = 0;
        }
                idetape_onstream_mode_sense_tape_parameter_page(drive, tape->debug_level);
    }
    if (idetape_wait_ready(drive, 60 * HZ)) {
        clear_bit(IDETAPE_BUSY, &tape->flags);
        printk(KERN_ERR "ide-tape: %s: drive not ready\n", tape->name);
        MOD_DEC_USE_COUNT;
        return -EBUSY;
    }
    idetape_read_position(drive);
    MOD_DEC_USE_COUNT;
    clear_bit (IDETAPE_PIPELINE_ERROR, &tape->flags);

    if (tape->chrdev_direction == idetape_direction_none) {
        MOD_INC_USE_COUNT;
        if (idetape_create_prevent_cmd(drive, &pc, 1)) {
            if (!idetape_queue_pc_tail (drive, &pc)) {
                if (tape->door_locked != DOOR_EXPLICITLY_LOCKED)
                    tape->door_locked = DOOR_LOCKED;
            }
        }
        idetape_analyze_headers(drive);
    }
    tape->max_frames = tape->cur_frames = tape->req_buffer_fill = 0;
    idetape_restart_speed_control(drive);
    tape->restart_speed_control_req = 0;
    return 0;
}

static void idetape_write_release (struct inode *inode)
{
    ide_drive_t *drive = get_drive_ptr (inode->i_rdev);
    idetape_tape_t *tape = drive->driver_data;
    unsigned int minor=MINOR (inode->i_rdev);

    idetape_empty_write_pipeline (drive);
    tape->merge_stage = __idetape_kmalloc_stage (tape, 1, 0);
    if (tape->merge_stage != NULL) {
        idetape_pad_zeros (drive, tape->tape_block_size * (tape->user_bs_factor - 1));
        __idetape_kfree_stage (tape->merge_stage);
        tape->merge_stage = NULL;
    }
    idetape_write_filemark(drive);
    idetape_write_eod(drive);
    idetape_flush_tape_buffers (drive);
    idetape_write_header(drive, minor >= 128);
    idetape_flush_tape_buffers (drive);

    return;
}

/*
 *    Our character device release function.
 */
static int idetape_chrdev_release (struct inode *inode, struct file *filp)
{
    ide_drive_t *drive = get_drive_ptr (inode->i_rdev);
    idetape_tape_t *tape;
    idetape_pc_t pc;
    unsigned int minor=MINOR (inode->i_rdev);

    lock_kernel();
    tape = drive->driver_data;
#if IDETAPE_DEBUG_LOG
    if (tape->debug_level >= 3)
        printk (KERN_INFO "ide-tape: Reached idetape_chrdev_release\n");
#endif /* IDETAPE_DEBUG_LOG */

    if (tape->chrdev_direction == idetape_direction_write) {
        idetape_write_release(inode);
    }
    if (tape->chrdev_direction == idetape_direction_read) {
        if (minor < 128)
            idetape_discard_read_pipeline (drive, 1);
        else
            idetape_wait_for_pipeline (drive);
    }
    if (tape->cache_stage != NULL) {
        __idetape_kfree_stage (tape->cache_stage);
        tape->cache_stage = NULL;
    }
    if (minor < 128)
        (void) idetape_rewind_tape (drive);
    if (tape->chrdev_direction == idetape_direction_none) {
        if (tape->door_locked != DOOR_EXPLICITLY_LOCKED) {
            if (idetape_create_prevent_cmd(drive, &pc, 0))
                if (!idetape_queue_pc_tail (drive, &pc))
                    tape->door_locked = DOOR_UNLOCKED;
        }
        MOD_DEC_USE_COUNT;
    }
    clear_bit (IDETAPE_BUSY, &tape->flags);
    unlock_kernel();
    return 0;
}

/*
 *    idetape_identify_device is called to check the contents of the
 *    ATAPI IDENTIFY command results. We return:
 *
 *    1    If the tape can be supported by us, based on the information
 *        we have so far.
 *
 *    0     If this tape driver is not currently supported by us.
 */
static int idetape_identify_device (ide_drive_t *drive,struct hd_driveid *id)
{
    struct idetape_id_gcw gcw;
#if IDETAPE_DEBUG_INFO
    unsigned short mask,i;
#endif /* IDETAPE_DEBUG_INFO */

    if (!id)
        return 0;

    *((unsigned short *) &gcw) = id->config;

#if IDETAPE_DEBUG_INFO
    printk (KERN_INFO "ide-tape: Dumping ATAPI Identify Device tape parameters\n");
    printk (KERN_INFO "ide-tape: Protocol Type: ");
    switch (gcw.protocol) {
        case 0: case 1: printk (KERN_INFO "ATA\n");break;
        case 2:    printk (KERN_INFO "ATAPI\n");break;
        case 3: printk (KERN_INFO "Reserved (Unknown to ide-tape)\n");break;
    }
    printk (KERN_INFO "ide-tape: Device Type: %x - ",gcw.device_type);    
    switch (gcw.device_type) {
        case 0: printk (KERN_INFO "Direct-access Device\n");break;
        case 1: printk (KERN_INFO "Streaming Tape Device\n");break;
        case 2: case 3: case 4: printk (KERN_INFO "Reserved\n");break;
        case 5: printk (KERN_INFO "CD-ROM Device\n");break;
        case 6: printk (KERN_INFO "Reserved\n");
        case 7: printk (KERN_INFO "Optical memory Device\n");break;
        case 0x1f: printk (KERN_INFO "Unknown or no Device type\n");break;
        default: printk (KERN_INFO "Reserved\n");
    }
    printk (KERN_INFO "ide-tape: Removable: %s",gcw.removable ? "Yes\n":"No\n");    
    printk (KERN_INFO "ide-tape: Command Packet DRQ Type: ");
    switch (gcw.drq_type) {
        case 0: printk (KERN_INFO "Microprocessor DRQ\n");break;
        case 1: printk (KERN_INFO "Interrupt DRQ\n");break;
        case 2: printk (KERN_INFO "Accelerated DRQ\n");break;
        case 3: printk (KERN_INFO "Reserved\n");break;
    }
    printk (KERN_INFO "ide-tape: Command Packet Size: ");
    switch (gcw.packet_size) {
        case 0: printk (KERN_INFO "12 bytes\n");break;
        case 1: printk (KERN_INFO "16 bytes\n");break;
        default: printk (KERN_INFO "Reserved\n");break;
    }
    printk (KERN_INFO "ide-tape: Model: %.40s\n",id->model);
    printk (KERN_INFO "ide-tape: Firmware Revision: %.8s\n",id->fw_rev);
    printk (KERN_INFO "ide-tape: Serial Number: %.20s\n",id->serial_no);
    printk (KERN_INFO "ide-tape: Write buffer size: %d bytes\n",id->buf_size*512);
    printk (KERN_INFO "ide-tape: DMA: %s",id->capability & 0x01 ? "Yes\n":"No\n");
    printk (KERN_INFO "ide-tape: LBA: %s",id->capability & 0x02 ? "Yes\n":"No\n");
    printk (KERN_INFO "ide-tape: IORDY can be disabled: %s",id->capability & 0x04 ? "Yes\n":"No\n");
    printk (KERN_INFO "ide-tape: IORDY supported: %s",id->capability & 0x08 ? "Yes\n":"Unknown\n");
    printk (KERN_INFO "ide-tape: ATAPI overlap supported: %s",id->capability & 0x20 ? "Yes\n":"No\n");
    printk (KERN_INFO "ide-tape: PIO Cycle Timing Category: %d\n",id->tPIO);
    printk (KERN_INFO "ide-tape: DMA Cycle Timing Category: %d\n",id->tDMA);
    printk (KERN_INFO "ide-tape: Single Word DMA supported modes: ");
    for (i=0,mask=1;i<8;i++,mask=mask << 1) {
        if (id->dma_1word & mask)
            printk (KERN_INFO "%d ",i);
        if (id->dma_1word & (mask << 8))
            printk (KERN_INFO "(active) ");
    }
    printk (KERN_INFO "\n");
    printk (KERN_INFO "ide-tape: Multi Word DMA supported modes: ");
    for (i=0,mask=1;i<8;i++,mask=mask << 1) {
        if (id->dma_mword & mask)
            printk (KERN_INFO "%d ",i);
        if (id->dma_mword & (mask << 8))
            printk (KERN_INFO "(active) ");
    }
    printk (KERN_INFO "\n");
    if (id->field_valid & 0x0002) {
        printk (KERN_INFO "ide-tape: Enhanced PIO Modes: %s\n",id->eide_pio_modes & 1 ? "Mode 3":"None");
        printk (KERN_INFO "ide-tape: Minimum Multi-word DMA cycle per word: ");
        if (id->eide_dma_min == 0)
            printk (KERN_INFO "Not supported\n");
        else
            printk (KERN_INFO "%d ns\n",id->eide_dma_min);

        printk (KERN_INFO "ide-tape: Manufacturer\'s Recommended Multi-word cycle: ");
        if (id->eide_dma_time == 0)
            printk (KERN_INFO "Not supported\n");
        else
            printk (KERN_INFO "%d ns\n",id->eide_dma_time);

        printk (KERN_INFO "ide-tape: Minimum PIO cycle without IORDY: ");
        if (id->eide_pio == 0)
            printk (KERN_INFO "Not supported\n");
        else
            printk (KERN_INFO "%d ns\n",id->eide_pio);

        printk (KERN_INFO "ide-tape: Minimum PIO cycle with IORDY: ");
        if (id->eide_pio_iordy == 0)
            printk (KERN_INFO "Not supported\n");
        else
            printk (KERN_INFO "%d ns\n",id->eide_pio_iordy);
        
    } else
        printk (KERN_INFO "ide-tape: According to the device, fields 64-70 are not valid.\n");
#endif /* IDETAPE_DEBUG_INFO */

    /* Check that we can support this device */

    if (gcw.protocol !=2 )
        printk (KERN_ERR "ide-tape: Protocol is not ATAPI\n");
    else if (gcw.device_type != 1)
        printk (KERN_ERR "ide-tape: Device type is not set to tape\n");
    else if (!gcw.removable)
        printk (KERN_ERR "ide-tape: The removable flag is not set\n");
    else if (gcw.packet_size != 0) {
        printk (KERN_ERR "ide-tape: Packet size is not 12 bytes long\n");
        if (gcw.packet_size == 1)
            printk (KERN_ERR "ide-tape: Sorry, padding to 16 bytes is still not supported\n");
    } else
        return 1;
    return 0;
}

/*
 * Notify vendor ID to the OnStream tape drive
 */
static void idetape_onstream_set_vendor (ide_drive_t *drive, char *vendor)
{
    idetape_pc_t pc;
    idetape_mode_parameter_header_t *header;

    idetape_create_mode_select_cmd(&pc, sizeof(*header) + 8);
    pc.buffer[0] = 3 + 8;    /* Mode Data Length */
    pc.buffer[1] = 0;    /* Medium Type - ignoring */
    pc.buffer[2] = 0;    /* Reserved */
    pc.buffer[3] = 0;    /* Block Descriptor Length */
    pc.buffer[4 + 0] = 0x36 | (1 << 7);
    pc.buffer[4 + 1] = 6;
    pc.buffer[4 + 2] = vendor[0];
    pc.buffer[4 + 3] = vendor[1];
    pc.buffer[4 + 4] = vendor[2];
    pc.buffer[4 + 5] = vendor[3];
    pc.buffer[4 + 6] = 0;
    pc.buffer[4 + 7] = 0;
    if (idetape_queue_pc_tail (drive, &pc))
        printk (KERN_ERR "ide-tape: Couldn't set vendor name to %s\n", vendor);

}

/*
 * Various unused OnStream commands
 */
#if ONSTREAM_DEBUG
static void idetape_onstream_set_retries (ide_drive_t *drive, int retries)
{
    idetape_pc_t pc;

    idetape_create_mode_select_cmd(&pc, sizeof(idetape_mode_parameter_header_t) + 4);
    pc.buffer[0] = 3 + 4;
    pc.buffer[1] = 0;    /* Medium Type - ignoring */
    pc.buffer[2] = 0;    /* Reserved */
    pc.buffer[3] = 0;    /* Block Descriptor Length */
    pc.buffer[4 + 0] = 0x2f | (1 << 7);
    pc.buffer[4 + 1] = 2;
    pc.buffer[4 + 2] = 4;
    pc.buffer[4 + 3] = retries;
    if (idetape_queue_pc_tail (drive, &pc))
        printk (KERN_ERR "ide-tape: Couldn't set retries to %d\n", retries);
}
#endif

/*
 * Configure 32.5KB block size.
 */
static void idetape_onstream_configure_block_size (ide_drive_t *drive)
{
    idetape_pc_t pc;
    idetape_mode_parameter_header_t *header;
    idetape_block_size_page_t *bs;

    /*
     * Get the current block size from the block size mode page
     */
    idetape_create_mode_sense_cmd (&pc, IDETAPE_BLOCK_SIZE_PAGE);
    if (idetape_queue_pc_tail (drive, &pc))
        printk (KERN_ERR "ide-tape: can't get tape block size mode page\n");
    header = (idetape_mode_parameter_header_t *) pc.buffer;
    bs = (idetape_block_size_page_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t) + header->bdl);

#if IDETAPE_DEBUG_INFO
    printk(KERN_INFO "ide-tape: 32KB play back: %s\n", bs->play32 ? "Yes" : "No");
    printk(KERN_INFO "ide-tape: 32.5KB play back: %s\n", bs->play32_5 ? "Yes" : "No");
    printk(KERN_INFO "ide-tape: 32KB record: %s\n", bs->record32 ? "Yes" : "No");
    printk(KERN_INFO "ide-tape: 32.5KB record: %s\n", bs->record32_5 ? "Yes" : "No");
#endif /* IDETAPE_DEBUG_INFO */

    /*
     * Configure default auto columns mode, 32.5KB block size
     */ 
    bs->one = 1;
    bs->play32 = 0;
    bs->play32_5 = 1;
    bs->record32 = 0;
    bs->record32_5 = 1;
    idetape_create_mode_select_cmd(&pc, sizeof(*header) + sizeof(*bs));
    if (idetape_queue_pc_tail (drive, &pc))
        printk (KERN_ERR "ide-tape: Couldn't set tape block size mode page\n");

#if ONSTREAM_DEBUG
    /*
     * In debug mode, we want to see as many errors as possible
     * to test the error recovery mechanism.
     */
    idetape_onstream_set_retries(drive, 0);
#endif
}

/*
 * Use INQUIRY to get the firmware revision
 */
static void idetape_get_inquiry_results (ide_drive_t *drive)
{
    char *r;
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t pc;
    idetape_inquiry_result_t *inquiry;
    
    idetape_create_inquiry_cmd(&pc);
    if (idetape_queue_pc_tail (drive, &pc)) {
        printk (KERN_ERR "ide-tape: %s: can't get INQUIRY results\n", tape->name);
        return;
    }
    inquiry = (idetape_inquiry_result_t *) pc.buffer;
    memcpy(tape->vendor_id, inquiry->vendor_id, 8);
    memcpy(tape->product_id, inquiry->product_id, 16);
    memcpy(tape->firmware_revision, inquiry->revision_level, 4);
    ide_fixstring(tape->vendor_id, 10, 0);
    ide_fixstring(tape->product_id, 18, 0);
    ide_fixstring(tape->firmware_revision, 6, 0);
    r = tape->firmware_revision;
    if (*(r + 1) == '.')
        tape->firmware_revision_num = (*r - '0') * 100 + (*(r + 2) - '0') * 10 + *(r + 3) - '0';
    else if (tape->onstream)
        tape->firmware_revision_num = (*r - '0') * 100 + (*(r + 1) - '0') * 10 + *(r + 2) - '0';
    printk(KERN_INFO "ide-tape: %s <-> %s: %s %s rev %s\n", drive->name, tape->name, tape->vendor_id, tape->product_id, tape->firmware_revision);
}

/*
 * Configure the OnStream ATAPI tape drive for default operation
 */
static void idetape_configure_onstream (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

    if (tape->firmware_revision_num < 105) {
        printk(KERN_INFO "ide-tape: %s: Old OnStream firmware revision detected (%s)\n", tape->name, tape->firmware_revision);
        printk(KERN_INFO "ide-tape: %s: An upgrade to version 1.05 or above is recommended\n", tape->name);
    }

    /*
     * Configure 32.5KB (data+aux) block size.
     */
    idetape_onstream_configure_block_size(drive);

    /*
     * Set vendor name to 'LIN3' for "Linux support version 3".
     */
    idetape_onstream_set_vendor(drive, "LIN3");
}

/*
 *    idetape_get_mode_sense_parameters asks the tape about its various
 *    parameters. This may work for other drives to???
 */
static void idetape_onstream_mode_sense_tape_parameter_page(ide_drive_t *drive, int debug)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t pc;
    idetape_mode_parameter_header_t *header;
    onstream_tape_paramtr_page_t *prm;
    
    idetape_create_mode_sense_cmd (&pc, IDETAPE_PARAMTR_PAGE);
    if (idetape_queue_pc_tail (drive, &pc)) {
        printk (KERN_ERR "ide-tape: Can't get tape parameters page - probably no tape inserted in onstream drive\n");
        return;
    }
    header = (idetape_mode_parameter_header_t *) pc.buffer;
    prm = (onstream_tape_paramtr_page_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t) + header->bdl);

        tape->capacity = ntohs(prm->segtrk) * ntohs(prm->trks);
        if (debug) {
        printk (KERN_INFO "ide-tape: %s <-> %s: Tape length %dMB (%d frames/track, %d tracks = %d blocks, density: %dKbpi)\n",
               drive->name, tape->name, tape->capacity/32, ntohs(prm->segtrk), ntohs(prm->trks), tape->capacity, prm->density);
        }

        return;
}

/*
 *    idetape_get_mode_sense_results asks the tape about its various
 *    parameters. In particular, we will adjust our data transfer buffer
 *    size to the recommended value as returned by the tape.
 */
static void idetape_get_mode_sense_results (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t pc;
    idetape_mode_parameter_header_t *header;
    idetape_capabilities_page_t *capabilities;
    
    idetape_create_mode_sense_cmd (&pc, IDETAPE_CAPABILITIES_PAGE);
    if (idetape_queue_pc_tail (drive, &pc)) {
        printk (KERN_ERR "ide-tape: Can't get tape parameters - assuming some default values\n");
        tape->tape_block_size = 512; tape->capabilities.ctl = 52;
        tape->capabilities.speed = 450; tape->capabilities.buffer_size = 6 * 52;
        return;
    }
    header = (idetape_mode_parameter_header_t *) pc.buffer;
    capabilities = (idetape_capabilities_page_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t) + header->bdl);

    capabilities->max_speed = ntohs (capabilities->max_speed);
    capabilities->ctl = ntohs (capabilities->ctl);
    capabilities->speed = ntohs (capabilities->speed);
    capabilities->buffer_size = ntohs (capabilities->buffer_size);

    if (!capabilities->speed) {
        printk(KERN_INFO "ide-tape: %s: overriding capabilities->speed (assuming 650KB/sec)\n", drive->name);
        capabilities->speed = 650;
    }
    if (!capabilities->max_speed) {
        printk(KERN_INFO "ide-tape: %s: overriding capabilities->max_speed (assuming 650KB/sec)\n", drive->name);
        capabilities->max_speed = 650;
    }

    tape->capabilities = *capabilities;        /* Save us a copy */
    if (capabilities->blk512)
        tape->tape_block_size = 512;
    else if (capabilities->blk1024)
        tape->tape_block_size = 1024;
    else if (tape->onstream && capabilities->blk32768)
        tape->tape_block_size = 32768;

#if IDETAPE_DEBUG_INFO
    printk (KERN_INFO "ide-tape: Dumping the results of the MODE SENSE packet command\n");
    printk (KERN_INFO "ide-tape: Mode Parameter Header:\n");
    printk (KERN_INFO "ide-tape: Mode Data Length - %d\n",header->mode_data_length);
    printk (KERN_INFO "ide-tape: Medium Type - %d\n",header->medium_type);
    printk (KERN_INFO "ide-tape: Device Specific Parameter - %d\n",header->dsp);
    printk (KERN_INFO "ide-tape: Block Descriptor Length - %d\n",header->bdl);
    
    printk (KERN_INFO "ide-tape: Capabilities and Mechanical Status Page:\n");
    printk (KERN_INFO "ide-tape: Page code - %d\n",capabilities->page_code);
    printk (KERN_INFO "ide-tape: Page length - %d\n",capabilities->page_length);
    printk (KERN_INFO "ide-tape: Read only - %s\n",capabilities->ro ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports reverse space - %s\n",capabilities->sprev ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports erase initiated formatting - %s\n",capabilities->efmt ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports QFA two Partition format - %s\n",capabilities->qfa ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports locking the medium - %s\n",capabilities->lock ? "Yes":"No");
    printk (KERN_INFO "ide-tape: The volume is currently locked - %s\n",capabilities->locked ? "Yes":"No");
    printk (KERN_INFO "ide-tape: The device defaults in the prevent state - %s\n",capabilities->prevent ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports ejecting the medium - %s\n",capabilities->eject ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports error correction - %s\n",capabilities->ecc ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports data compression - %s\n",capabilities->cmprs ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports 512 bytes block size - %s\n",capabilities->blk512 ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports 1024 bytes block size - %s\n",capabilities->blk1024 ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Supports 32768 bytes block size / Restricted byte count for PIO transfers - %s\n",capabilities->blk32768 ? "Yes":"No");
    printk (KERN_INFO "ide-tape: Maximum supported speed in KBps - %d\n",capabilities->max_speed);
    printk (KERN_INFO "ide-tape: Continuous transfer limits in blocks - %d\n",capabilities->ctl);
    printk (KERN_INFO "ide-tape: Current speed in KBps - %d\n",capabilities->speed);    
    printk (KERN_INFO "ide-tape: Buffer size - %d\n",capabilities->buffer_size*512);
#endif /* IDETAPE_DEBUG_INFO */
}

/*
 *    ide_get_blocksize_from_block_descriptor does a mode sense page 0 with block descriptor
 *    and if it succeeds sets the tape block size with the reported value
 */
static void idetape_get_blocksize_from_block_descriptor(ide_drive_t *drive)
{

    idetape_tape_t *tape = drive->driver_data;
    idetape_pc_t pc;
    idetape_mode_parameter_header_t *header;
    idetape_parameter_block_descriptor_t *block_descrp;
    
    idetape_create_mode_sense_cmd (&pc, IDETAPE_BLOCK_DESCRIPTOR);
    if (idetape_queue_pc_tail (drive, &pc)) {
        printk (KERN_ERR "ide-tape: Can't get block descriptor\n");
        if (tape->tape_block_size == 0) {
            printk(KERN_WARNING "ide-tape: Cannot deal with zero block size, assume 32k\n");
            tape->tape_block_size =  32768;
        }
        return;
    }
    header = (idetape_mode_parameter_header_t *) pc.buffer;
    block_descrp = (idetape_parameter_block_descriptor_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t));
    tape->tape_block_size =( block_descrp->length[0]<<16) + (block_descrp->length[1]<<8) + block_descrp->length[2];
#if IDETAPE_DEBUG_INFO
    printk (KERN_INFO "ide-tape: Adjusted block size - %d\n", tape->tape_block_size);
#endif /* IDETAPE_DEBUG_INFO */
}
static void idetape_add_settings (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;

/*
 *            drive    setting name    read/write    ioctl    ioctl        data type    min            max            mul_factor            div_factor            data pointer                set function
 */
    ide_add_setting(drive,    "buffer",    SETTING_READ,    -1,    -1,        TYPE_SHORT,    0,            0xffff,            1,                2,                &tape->capabilities.buffer_size,    NULL);
    ide_add_setting(drive,    "pipeline_min",    SETTING_RW,    -1,    -1,        TYPE_INT,    2,            0xffff,            tape->stage_size / 1024,    1,                &tape->min_pipeline,            NULL);
    ide_add_setting(drive,    "pipeline",    SETTING_RW,    -1,    -1,        TYPE_INT,    2,            0xffff,            tape->stage_size / 1024,    1,                &tape->max_stages,            NULL);
    ide_add_setting(drive,    "pipeline_max",    SETTING_RW,    -1,    -1,        TYPE_INT,    2,            0xffff,            tape->stage_size / 1024,    1,                &tape->max_pipeline,            NULL);
    ide_add_setting(drive,    "pipeline_used",SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            tape->stage_size / 1024,    1,                &tape->nr_stages,            NULL);
    ide_add_setting(drive,    "pipeline_pending",SETTING_READ,-1,    -1,        TYPE_INT,    0,            0xffff,            tape->stage_size / 1024,    1,                &tape->nr_pending_stages,        NULL);
    ide_add_setting(drive,    "speed",    SETTING_READ,    -1,    -1,        TYPE_SHORT,    0,            0xffff,            1,                1,                &tape->capabilities.speed,        NULL);
    ide_add_setting(drive,    "stage",    SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1024,                &tape->stage_size,            NULL);
    ide_add_setting(drive,    "tdsc",        SETTING_RW,    -1,    -1,        TYPE_INT,    IDETAPE_DSC_RW_MIN,    IDETAPE_DSC_RW_MAX,    1000,                HZ,                &tape->best_dsc_rw_frequency,        NULL);
    ide_add_setting(drive,    "dsc_overlap",    SETTING_RW,    -1,    -1,        TYPE_BYTE,    0,            1,            1,                1,                &drive->dsc_overlap,            NULL);
    ide_add_setting(drive,    "pipeline_head_speed_c",SETTING_READ,    -1,    -1,    TYPE_INT,    0,            0xffff,            1,                1,                &tape->controlled_pipeline_head_speed,    NULL);
    ide_add_setting(drive,    "pipeline_head_speed_u",SETTING_READ,    -1,    -1,    TYPE_INT,    0,            0xffff,            1,                1,                &tape->uncontrolled_pipeline_head_speed,    NULL);
    ide_add_setting(drive,    "avg_speed",    SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->avg_speed,        NULL);
    ide_add_setting(drive,    "debug_level",SETTING_RW,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->debug_level,        NULL);
    if (tape->onstream) {
        ide_add_setting(drive,    "cur_frames",    SETTING_READ,    -1,    -1,        TYPE_SHORT,    0,            0xffff,            1,                1,                &tape->cur_frames,        NULL);
        ide_add_setting(drive,    "max_frames",    SETTING_READ,    -1,    -1,        TYPE_SHORT,    0,            0xffff,            1,                1,                &tape->max_frames,        NULL);
        ide_add_setting(drive,    "insert_speed",    SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->insert_speed,        NULL);
        ide_add_setting(drive,    "speed_control",SETTING_RW,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->speed_control,        NULL);
        ide_add_setting(drive,    "tape_still_time",SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->tape_still_time,        NULL);
        ide_add_setting(drive,    "max_insert_speed",SETTING_RW,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->max_insert_speed,    NULL);
        ide_add_setting(drive,    "insert_size",    SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->insert_size,        NULL);
        ide_add_setting(drive,    "capacity",    SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->capacity,        NULL);
        ide_add_setting(drive,    "first_frame",    SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->first_frame_position,        NULL);
        ide_add_setting(drive,    "logical_blk",    SETTING_READ,    -1,    -1,        TYPE_INT,    0,            0xffff,            1,                1,                &tape->logical_blk_num,        NULL);
    }
}

/*
 *    ide_setup is called to:
 *
 *        1.    Initialize our various state variables.
 *        2.    Ask the tape for its capabilities.
 *        3.    Allocate a buffer which will be used for data
 *            transfer. The buffer size is chosen based on
 *            the recommendation which we received in step (2).
 *
 *    Note that at this point ide.c already assigned us an irq, so that
 *    we can queue requests here and wait for their completion.
 */
static void idetape_setup (ide_drive_t *drive, idetape_tape_t *tape, int minor)
{
    unsigned long t1, tmid, tn, t;
    int speed;
    struct idetape_id_gcw gcw;
    int stage_size;
    struct sysinfo si;

    memset (tape, 0, sizeof (idetape_tape_t));
    spin_lock_init(&tape->spinlock);
    drive->driver_data = tape;
    drive->ready_stat = 0;            /* An ATAPI device ignores DRDY */
    if (strstr(drive->id->model, "OnStream DI-"))
        tape->onstream = 1;
    drive->dsc_overlap = 1;
#ifdef CONFIG_BLK_DEV_IDEPCI
    if (!tape->onstream && HWIF(drive)->pci_dev != NULL) {
        /*
         * These two ide-pci host adapters appear to need DSC overlap disabled.
         * This probably needs further analysis.
         */
        if ((HWIF(drive)->pci_dev->device == PCI_DEVICE_ID_ARTOP_ATP850UF) ||
            (HWIF(drive)->pci_dev->device == PCI_DEVICE_ID_TTI_HPT343)) {
            printk(KERN_INFO "ide-tape: %s: disabling DSC overlap\n", tape->name);
                drive->dsc_overlap = 0;
        }
    }
#endif /* CONFIG_BLK_DEV_IDEPCI */
    tape->drive = drive;
    tape->minor = minor;
    tape->name[0] = 'h'; tape->name[1] = 't'; tape->name[2] = '0' + minor;
    tape->chrdev_direction = idetape_direction_none;
    tape->pc = tape->pc_stack;
    tape->max_insert_speed = 10000;
    tape->speed_control = 1;
    *((unsigned short *) &gcw) = drive->id->config;
    if (gcw.drq_type == 1)
        set_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags);

    tape->min_pipeline = tape->max_pipeline = tape->max_stages = 10;
    
    idetape_get_inquiry_results(drive);
    idetape_get_mode_sense_results(drive);
    idetape_get_blocksize_from_block_descriptor(drive);
    if (tape->onstream) {
        idetape_onstream_mode_sense_tape_parameter_page(drive, 1);
        idetape_configure_onstream(drive);
    }
    tape->user_bs_factor = 1;
    tape->stage_size = tape->capabilities.ctl * tape->tape_block_size;
    while (tape->stage_size > 0xffff) {
        printk (KERN_NOTICE "ide-tape: decreasing stage size\n");
        tape->capabilities.ctl /= 2;
        tape->stage_size = tape->capabilities.ctl * tape->tape_block_size;
    }
    stage_size = tape->stage_size;
    if (tape->onstream)
        stage_size = 32768 + 512;
    tape->pages_per_stage = stage_size / PAGE_SIZE;
    if (stage_size % PAGE_SIZE) {
        tape->pages_per_stage++;
        tape->excess_bh_size = PAGE_SIZE - stage_size % PAGE_SIZE;
    }

    /*
     *    Select the "best" DSC read/write polling frequency
     *    and pipeline size.
     */
    speed = IDE_MAX (tape->capabilities.speed, tape->capabilities.max_speed);

    tape->max_stages = speed * 1000 * 10 / tape->stage_size;

    /*
     *     Limit memory use for pipeline to 10% of physical memory
     */
    si_meminfo(&si);
    if ( tape->max_stages * tape->stage_size > si.totalram * si.mem_unit / 10)
        tape->max_stages = si.totalram * si.mem_unit / (10 * tape->stage_size);
    tape->min_pipeline = tape->max_stages;
    tape->max_pipeline = tape->max_stages * 2;

    t1 = (tape->stage_size * HZ) / (speed * 1000);
    tmid = (tape->capabilities.buffer_size * 32 * HZ) / (speed * 125);
    tn = (IDETAPE_FIFO_THRESHOLD * tape->stage_size * HZ) / (speed * 1000);

    if (tape->max_stages)
        t = tn;
    else
        t = t1;

    /*
     *    Ensure that the number we got makes sense; limit
     *    it within IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
     */
    tape->best_dsc_rw_frequency = IDE_MAX (IDE_MIN (t, IDETAPE_DSC_RW_MAX), IDETAPE_DSC_RW_MIN);
    printk (KERN_INFO "ide-tape: %s <-> %s: %dKBps, %d*%dkB buffer, %dkB pipeline, %lums tDSC%s\n",
        drive->name, tape->name, tape->capabilities.speed, (tape->capabilities.buffer_size * 512) / tape->stage_size,
        tape->stage_size / 1024, tape->max_stages * tape->stage_size / 1024,
        tape->best_dsc_rw_frequency * 1000 / HZ, drive->using_dma ? ", DMA":"");

    idetape_add_settings(drive);
}

static int idetape_cleanup (ide_drive_t *drive)
{
    idetape_tape_t *tape = drive->driver_data;
    int minor = tape->minor;
    unsigned long flags;

    save_flags (flags);    /* all CPUs (overkill?) */
    cli();            /* all CPUs (overkill?) */
    if (test_bit (IDETAPE_BUSY, &tape->flags) || tape->first_stage != NULL || tape->merge_stage_size || drive->usage) {
        restore_flags(flags);    /* all CPUs (overkill?) */
        return 1;
    }
    idetape_chrdevs[minor].drive = NULL;
    restore_flags (flags);    /* all CPUs (overkill?) */
    DRIVER(drive)->busy = 0;
    (void) ide_unregister_subdriver (drive);
    drive->driver_data = NULL;
    devfs_unregister (tape->de_r);
    devfs_unregister (tape->de_n);
    kfree (tape);
    for (minor = 0; minor < MAX_HWIFS * MAX_DRIVES; minor++)
        if (idetape_chrdevs[minor].drive != NULL)
            return 0;
    devfs_unregister_chrdev (IDETAPE_MAJOR, "ht");
    idetape_chrdev_present = 0;
    return 0;
}

#ifdef CONFIG_PROC_FS

static int proc_idetape_read_name
    (char *page, char **start, off_t off, int count, int *eof, void *data)
{
    ide_drive_t    *drive = (ide_drive_t *) data;
    idetape_tape_t    *tape = drive->driver_data;
    char        *out = page;
    int        len;

    len = sprintf(out, "%s\n", tape->name);
    PROC_IDE_READ_RETURN(page, start, off, count, eof, len);
}

static ide_proc_entry_t idetape_proc[] = {
    { "name",    S_IFREG|S_IRUGO,    proc_idetape_read_name,    NULL },
    { NULL, 0, NULL, NULL }
};

#else

#define    idetape_proc    NULL

#endif

static int idetape_reinit (ide_drive_t *drive)
{
    return 0;
}

/*
 *    IDE subdriver functions, registered with ide.c
 */
static ide_driver_t idetape_driver = {
    name:            "ide-tape",
    version:        IDETAPE_VERSION,
    media:            ide_tape,
    busy:            1,
    supports_dma:        1,
    supports_dsc_overlap:     1,
    cleanup:        idetape_cleanup,
    do_request:        idetape_do_request,
    end_request:        idetape_end_request,
    ioctl:            idetape_blkdev_ioctl,
    open:            idetape_blkdev_open,
    release:        idetape_blkdev_release,
    media_change:        NULL,
    revalidate:        NULL,
    pre_reset:        idetape_pre_reset,
    capacity:        NULL,
    proc:            idetape_proc,
    driver_reinit:        idetape_reinit,
};

int idetape_init (void);
static ide_module_t idetape_module = {
    IDE_DRIVER_MODULE,
    idetape_init,
    &idetape_driver,
    NULL
};

/*
 *    Our character device supporting functions, passed to register_chrdev.
 */
static struct file_operations idetape_fops = {
    owner:        THIS_MODULE,
    read:        idetape_chrdev_read,
    write:        idetape_chrdev_write,
    ioctl:        idetape_chrdev_ioctl,
    open:        idetape_chrdev_open,
    release:    idetape_chrdev_release,
};

MODULE_DESCRIPTION("ATAPI Streaming TAPE Driver");
MODULE_LICENSE("GPL");

static void __exit idetape_exit (void)
{
    ide_drive_t *drive;
    int minor;

    for (minor = 0; minor < MAX_HWIFS * MAX_DRIVES; minor++) {
        drive = idetape_chrdevs[minor].drive;
        if (drive != NULL && idetape_cleanup (drive))
        printk (KERN_ERR "ide-tape: %s: cleanup_module() called while still busy\n", drive->name);
    }
    ide_unregister_module(&idetape_module);
}

/*
 *    idetape_init will register the driver for each tape.
 */
int idetape_init (void)
{
    ide_drive_t *drive;
    idetape_tape_t *tape;
    int minor, failed = 0, supported = 0;

    MOD_INC_USE_COUNT;
#if ONSTREAM_DEBUG
        printk(KERN_INFO "ide-tape: MOD_INC_USE_COUNT in idetape_init\n");
#endif
    if (!idetape_chrdev_present)
        for (minor = 0; minor < MAX_HWIFS * MAX_DRIVES; minor++ )
            idetape_chrdevs[minor].drive = NULL;

    if ((drive = ide_scan_devices (ide_tape, idetape_driver.name, NULL, failed++)) == NULL) {
        ide_register_module (&idetape_module);
        MOD_DEC_USE_COUNT;
#if ONSTREAM_DEBUG
        printk(KERN_INFO "ide-tape: MOD_DEC_USE_COUNT in idetape_init\n");
#endif
        return 0;
    }
    if (!idetape_chrdev_present &&
        devfs_register_chrdev (IDETAPE_MAJOR, "ht", &idetape_fops)) {
        printk (KERN_ERR "ide-tape: Failed to register character device interface\n");
        MOD_DEC_USE_COUNT;
#if ONSTREAM_DEBUG
        printk(KERN_INFO "ide-tape: MOD_DEC_USE_COUNT in idetape_init\n");
#endif
        return -EBUSY;
    }
    do {
        if (!idetape_identify_device (drive, drive->id)) {
            printk (KERN_ERR "ide-tape: %s: not supported by this version of ide-tape\n", drive->name);
            continue;
        }
        if (drive->scsi) {
            if (strstr(drive->id->model, "OnStream DI-")) {
                printk("ide-tape: ide-scsi emulation is not supported for %s.\n", drive->id->model);
            } else {
                printk("ide-tape: passing drive %s to ide-scsi emulation.\n", drive->name);
                continue;
            }
        }
        tape = (idetape_tape_t *) kmalloc (sizeof (idetape_tape_t), GFP_KERNEL);
        if (tape == NULL) {
            printk (KERN_ERR "ide-tape: %s: Can't allocate a tape structure\n", drive->name);
            continue;
        }
        if (ide_register_subdriver (drive, &idetape_driver, IDE_SUBDRIVER_VERSION)) {
            printk (KERN_ERR "ide-tape: %s: Failed to register the driver with ide.c\n", drive->name);
            kfree (tape);
            continue;
        }
        for (minor = 0; idetape_chrdevs[minor].drive != NULL; minor++);
        idetape_setup (drive, tape, minor);
        idetape_chrdevs[minor].drive = drive;
        tape->de_r =
            devfs_register (drive->de, "mt", DEVFS_FL_DEFAULT,
                    HWIF(drive)->major, minor,
                    S_IFCHR | S_IRUGO | S_IWUGO,
                    &idetape_fops, NULL);
        tape->de_n =
            devfs_register (drive->de, "mtn", DEVFS_FL_DEFAULT,
                    HWIF(drive)->major, minor + 128,
                    S_IFCHR | S_IRUGO | S_IWUGO,
                    &idetape_fops, NULL);
        devfs_register_tape (tape->de_r);
        supported++; failed--;
    } while ((drive = ide_scan_devices (ide_tape, idetape_driver.name, NULL, failed++)) != NULL);
    if (!idetape_chrdev_present && !supported) {
        devfs_unregister_chrdev (IDETAPE_MAJOR, "ht");
    } else
        idetape_chrdev_present = 1;
    ide_register_module (&idetape_module);
    MOD_DEC_USE_COUNT;
#if ONSTREAM_DEBUG
    printk(KERN_INFO "ide-tape: MOD_DEC_USE_COUNT in idetape_init\n");
#endif
    return 0;
}

module_init(idetape_init);
module_exit(idetape_exit);

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