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/*
* linux/arch/m68k/atari/stmda.c
*
* Copyright (C) 1994 Roman Hodek
*
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of this archive
* for more details.
*/
/* This file contains some function for controlling the access to the */
/* ST-DMA chip that may be shared between devices. Currently we have: */
/* TT: Floppy and ACSI bus */
/* Falcon: Floppy and SCSI */
/* */
/* The controlling functions set up a wait queue for access to the */
/* ST-DMA chip. Callers to stdma_lock() that cannot granted access are */
/* put onto a queue and waked up later if the owner calls */
/* stdma_release(). Additionally, the caller gives his interrupt */
/* service routine to stdma_lock(). */
/* */
/* On the Falcon, the IDE bus uses just the ACSI/Floppy interrupt, but */
/* not the ST-DMA chip itself. So falhd.c needs not to lock the */
/* chip. The interrupt is routed to falhd.c if IDE is configured, the */
/* model is a Falcon and the interrupt was caused by the HD controller */
/* (can be determined by looking at its status register). */
#include <linux/types.h>
#include <linux/kdev_t.h>
#include <linux/genhd.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <asm/atari_stdma.h>
#include <asm/atariints.h>
#include <asm/atarihw.h>
#include <asm/io.h>
#include <asm/irq.h>
static int stdma_locked = 0; /* the semaphore */
/* int func to be called */
static void (*stdma_isr)(int, void *, struct pt_regs *) = NULL;
static void *stdma_isr_data = NULL; /* data passed to isr */
static DECLARE_WAIT_QUEUE_HEAD(stdma_wait); /* wait queue for ST-DMA */
/***************************** Prototypes *****************************/
static void stdma_int (int irq, void *dummy, struct pt_regs *fp);
/************************* End of Prototypes **************************/
/*
* Function: void stdma_lock( isrfunc isr, void *data )
*
* Purpose: Tries to get a lock on the ST-DMA chip that is used by more
* then one device driver. Waits on stdma_wait until lock is free.
* stdma_lock() may not be called from an interrupt! You have to
* get the lock in your main routine and release it when your
* request is finished.
*
* Inputs: A interrupt function that is called until the lock is
* released.
*
* Returns: nothing
*
*/
void stdma_lock(void (*handler)(int, void *, struct pt_regs *), void *data)
{
unsigned long oldflags;
save_flags(oldflags);
cli(); /* protect lock */
while(stdma_locked)
/* Since the DMA is used for file system purposes, we
have to sleep uninterruptible (there may be locked
buffers) */
sleep_on(&stdma_wait);
stdma_locked = 1;
stdma_isr = handler;
stdma_isr_data = data;
restore_flags(oldflags);
}
/*
* Function: void stdma_release( void )
*
* Purpose: Releases the lock on the ST-DMA chip.
*
* Inputs: none
*
* Returns: nothing
*
*/
void stdma_release(void)
{
unsigned long oldflags;
save_flags(oldflags);
cli();
stdma_locked = 0;
stdma_isr = NULL;
stdma_isr_data = NULL;
wake_up(&stdma_wait);
restore_flags(oldflags);
}
/*
* Function: int stdma_others_waiting( void )
*
* Purpose: Check if someone waits for the ST-DMA lock.
*
* Inputs: none
*
* Returns: 0 if no one is waiting, != 0 otherwise
*
*/
int stdma_others_waiting(void)
{
return waitqueue_active(&stdma_wait);
}
/*
* Function: int stdma_islocked( void )
*
* Purpose: Check if the ST-DMA is currently locked.
* Note: Returned status is only valid if ints are disabled while calling and
* as long as they remain disabled.
* If called with ints enabled, status can change only from locked to
* unlocked, because ints may not lock the ST-DMA.
*
* Inputs: none
*
* Returns: != 0 if locked, 0 otherwise
*
*/
int stdma_islocked(void)
{
return stdma_locked;
}
/*
* Function: void stdma_init( void )
*
* Purpose: Initialize the ST-DMA chip access controlling.
* It sets up the interrupt and its service routine. The int is registered
* as slow int, client devices have to live with that (no problem
* currently).
*
* Inputs: none
*
* Return: nothing
*
*/
void __init stdma_init(void)
{
stdma_isr = NULL;
request_irq(IRQ_MFP_FDC, stdma_int, IRQ_TYPE_SLOW,
"ST-DMA: floppy/ACSI/IDE/Falcon-SCSI", stdma_int);
}
/*
* Function: void stdma_int()
*
* Purpose: The interrupt routine for the ST-DMA. It calls the isr
* registered by stdma_lock().
*
*/
static void stdma_int(int irq, void *dummy, struct pt_regs *fp)
{
if (stdma_isr)
(*stdma_isr)(irq, stdma_isr_data, fp);
}
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