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/*
* Real Time Clock interface for Linux
*
* Copyright (C) 1996 Paul Gortmaker
*
* This driver allows use of the real time clock (built into
* nearly all computers) from user space. It exports the /dev/rtc
* interface supporting various ioctl() and also the
* /proc/driver/rtc pseudo-file for status information.
*
* The ioctls can be used to set the interrupt behaviour and
* generation rate from the RTC via IRQ 8. Then the /dev/rtc
* interface can be used to make use of these timer interrupts,
* be they interval or alarm based.
*
* The /dev/rtc interface will block on reads until an interrupt
* has been received. If a RTC interrupt has already happened,
* it will output an unsigned long and then block. The output value
* contains the interrupt status in the low byte and the number of
* interrupts since the last read in the remaining high bytes. The
* /dev/rtc interface can also be used with the select(2) call.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Based on other minimal char device drivers, like Alan's
* watchdog, Ted's random, etc. etc.
*
* 1.07 Paul Gortmaker.
* 1.08 Miquel van Smoorenburg: disallow certain things on the
* DEC Alpha as the CMOS clock is also used for other things.
* 1.09 Nikita Schmidt: epoch support and some Alpha cleanup.
* 1.09a Pete Zaitcev: Sun SPARC
* 1.09b Jeff Garzik: Modularize, init cleanup
* 1.09c Jeff Garzik: SMP cleanup
* 1.10 Paul Barton-Davis: add support for async I/O
* 1.10a Andrea Arcangeli: Alpha updates
* 1.10b Andrew Morton: SMP lock fix
* 1.10c Cesar Barros: SMP locking fixes and cleanup
* 1.10d Paul Gortmaker: delete paranoia check in rtc_exit
* 1.10e Maciej W. Rozycki: Handle DECstation's year weirdness.
*/
#define RTC_VERSION "1.10e"
#define RTC_IO_EXTENT 0x10 /* Only really two ports, but... */
/*
* Note that *all* calls to CMOS_READ and CMOS_WRITE are done with
* interrupts disabled. Due to the index-port/data-port (0x70/0x71)
* design of the RTC, we don't want two different things trying to
* get to it at once. (e.g. the periodic 11 min sync from time.c vs.
* this driver.)
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/mc146818rtc.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#ifdef __sparc__
#include <asm/ebus.h>
#ifdef __sparc_v9__
#include <asm/isa.h>
#endif
static unsigned long rtc_port;
static int rtc_irq = PCI_IRQ_NONE;
#endif
static int rtc_has_irq = 1;
/*
* We sponge a minor off of the misc major. No need slurping
* up another valuable major dev number for this. If you add
* an ioctl, make sure you don't conflict with SPARC's RTC
* ioctls.
*/
static struct fasync_struct *rtc_async_queue;
static DECLARE_WAIT_QUEUE_HEAD(rtc_wait);
static struct timer_list rtc_irq_timer;
static ssize_t rtc_read(struct file *file, char *buf,
size_t count, loff_t *ppos);
static int rtc_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg);
#if RTC_IRQ
static unsigned int rtc_poll(struct file *file, poll_table *wait);
#endif
static void get_rtc_time (struct rtc_time *rtc_tm);
static void get_rtc_alm_time (struct rtc_time *alm_tm);
#if RTC_IRQ
static void rtc_dropped_irq(unsigned long data);
static void set_rtc_irq_bit(unsigned char bit);
static void mask_rtc_irq_bit(unsigned char bit);
#endif
static inline unsigned char rtc_is_updating(void);
static int rtc_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data);
/*
* Bits in rtc_status. (6 bits of room for future expansion)
*/
#define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */
#define RTC_TIMER_ON 0x02 /* missed irq timer active */
/*
* rtc_status is never changed by rtc_interrupt, and ioctl/open/close is
* protected by the big kernel lock. However, ioctl can still disable the timer
* in rtc_status and then with del_timer after the interrupt has read
* rtc_status but before mod_timer is called, which would then reenable the
* timer (but you would need to have an awful timing before you'd trip on it)
*/
static unsigned long rtc_status = 0; /* bitmapped status byte. */
static unsigned long rtc_freq = 0; /* Current periodic IRQ rate */
static unsigned long rtc_irq_data = 0; /* our output to the world */
/*
* If this driver ever becomes modularised, it will be really nice
* to make the epoch retain its value across module reload...
*/
static unsigned long epoch = 1900; /* year corresponding to 0x00 */
static const unsigned char days_in_mo[] =
{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
#if RTC_IRQ
/*
* A very tiny interrupt handler. It runs with SA_INTERRUPT set,
* but there is possibility of conflicting with the set_rtc_mmss()
* call (the rtc irq and the timer irq can easily run at the same
* time in two different CPUs). So we need to serializes
* accesses to the chip with the rtc_lock spinlock that each
* architecture should implement in the timer code.
* (See ./arch/XXXX/kernel/time.c for the set_rtc_mmss() function.)
*/
static void rtc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
/*
* Can be an alarm interrupt, update complete interrupt,
* or a periodic interrupt. We store the status in the
* low byte and the number of interrupts received since
* the last read in the remainder of rtc_irq_data.
*/
spin_lock (&rtc_lock);
rtc_irq_data += 0x100;
rtc_irq_data &= ~0xff;
rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);
if (rtc_status & RTC_TIMER_ON)
mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
spin_unlock (&rtc_lock);
/* Now do the rest of the actions */
wake_up_interruptible(&rtc_wait);
kill_fasync (&rtc_async_queue, SIGIO, POLL_IN);
}
#endif
/*
* Now all the various file operations that we export.
*/
static ssize_t rtc_read(struct file *file, char *buf,
size_t count, loff_t *ppos)
{
#if !RTC_IRQ
return -EIO;
#else
DECLARE_WAITQUEUE(wait, current);
unsigned long data;
ssize_t retval;
if (rtc_has_irq == 0)
return -EIO;
if (count < sizeof(unsigned long))
return -EINVAL;
add_wait_queue(&rtc_wait, &wait);
current->state = TASK_INTERRUPTIBLE;
do {
/* First make it right. Then make it fast. Putting this whole
* block within the parentheses of a while would be too
* confusing. And no, xchg() is not the answer. */
spin_lock_irq (&rtc_lock);
data = rtc_irq_data;
rtc_irq_data = 0;
spin_unlock_irq (&rtc_lock);
if (data != 0)
break;
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
goto out;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
goto out;
}
schedule();
} while (1);
retval = put_user(data, (unsigned long *)buf);
if (!retval)
retval = sizeof(unsigned long);
out:
current->state = TASK_RUNNING;
remove_wait_queue(&rtc_wait, &wait);
return retval;
#endif
}
static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
struct rtc_time wtime;
#if RTC_IRQ
if (rtc_has_irq == 0) {
switch (cmd) {
case RTC_AIE_OFF:
case RTC_AIE_ON:
case RTC_PIE_OFF:
case RTC_PIE_ON:
case RTC_UIE_OFF:
case RTC_UIE_ON:
case RTC_IRQP_READ:
case RTC_IRQP_SET:
return -EINVAL;
};
}
#endif
switch (cmd) {
#if RTC_IRQ
case RTC_AIE_OFF: /* Mask alarm int. enab. bit */
{
mask_rtc_irq_bit(RTC_AIE);
return 0;
}
case RTC_AIE_ON: /* Allow alarm interrupts. */
{
set_rtc_irq_bit(RTC_AIE);
return 0;
}
case RTC_PIE_OFF: /* Mask periodic int. enab. bit */
{
mask_rtc_irq_bit(RTC_PIE);
if (rtc_status & RTC_TIMER_ON) {
spin_lock_irq (&rtc_lock);
rtc_status &= ~RTC_TIMER_ON;
del_timer(&rtc_irq_timer);
spin_unlock_irq (&rtc_lock);
}
return 0;
}
case RTC_PIE_ON: /* Allow periodic ints */
{
/*
* We don't really want Joe User enabling more
* than 64Hz of interrupts on a multi-user machine.
*/
if ((rtc_freq > 64) && (!capable(CAP_SYS_RESOURCE)))
return -EACCES;
if (!(rtc_status & RTC_TIMER_ON)) {
spin_lock_irq (&rtc_lock);
rtc_irq_timer.expires = jiffies + HZ/rtc_freq + 2*HZ/100;
add_timer(&rtc_irq_timer);
rtc_status |= RTC_TIMER_ON;
spin_unlock_irq (&rtc_lock);
}
set_rtc_irq_bit(RTC_PIE);
return 0;
}
case RTC_UIE_OFF: /* Mask ints from RTC updates. */
{
mask_rtc_irq_bit(RTC_UIE);
return 0;
}
case RTC_UIE_ON: /* Allow ints for RTC updates. */
{
set_rtc_irq_bit(RTC_UIE);
return 0;
}
#endif
case RTC_ALM_READ: /* Read the present alarm time */
{
/*
* This returns a struct rtc_time. Reading >= 0xc0
* means "don't care" or "match all". Only the tm_hour,
* tm_min, and tm_sec values are filled in.
*/
get_rtc_alm_time(&wtime);
break;
}
case RTC_ALM_SET: /* Store a time into the alarm */
{
/*
* This expects a struct rtc_time. Writing 0xff means
* "don't care" or "match all". Only the tm_hour,
* tm_min and tm_sec are used.
*/
unsigned char hrs, min, sec;
struct rtc_time alm_tm;
if (copy_from_user(&alm_tm, (struct rtc_time*)arg,
sizeof(struct rtc_time)))
return -EFAULT;
hrs = alm_tm.tm_hour;
min = alm_tm.tm_min;
sec = alm_tm.tm_sec;
if (hrs >= 24)
hrs = 0xff;
if (min >= 60)
min = 0xff;
if (sec >= 60)
sec = 0xff;
spin_lock_irq(&rtc_lock);
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) ||
RTC_ALWAYS_BCD)
{
BIN_TO_BCD(sec);
BIN_TO_BCD(min);
BIN_TO_BCD(hrs);
}
CMOS_WRITE(hrs, RTC_HOURS_ALARM);
CMOS_WRITE(min, RTC_MINUTES_ALARM);
CMOS_WRITE(sec, RTC_SECONDS_ALARM);
spin_unlock_irq(&rtc_lock);
return 0;
}
case RTC_RD_TIME: /* Read the time/date from RTC */
{
get_rtc_time(&wtime);
break;
}
case RTC_SET_TIME: /* Set the RTC */
{
struct rtc_time rtc_tm;
unsigned char mon, day, hrs, min, sec, leap_yr;
unsigned char save_control, save_freq_select;
unsigned int yrs;
#ifdef CONFIG_DECSTATION
unsigned int real_yrs;
#endif
if (!capable(CAP_SYS_TIME))
return -EACCES;
if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
sizeof(struct rtc_time)))
return -EFAULT;
yrs = rtc_tm.tm_year + 1900;
mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */
day = rtc_tm.tm_mday;
hrs = rtc_tm.tm_hour;
min = rtc_tm.tm_min;
sec = rtc_tm.tm_sec;
if (yrs < 1970)
return -EINVAL;
leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
if ((mon > 12) || (day == 0))
return -EINVAL;
if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
return -EINVAL;
if ((hrs >= 24) || (min >= 60) || (sec >= 60))
return -EINVAL;
if ((yrs -= epoch) > 255) /* They are unsigned */
return -EINVAL;
spin_lock_irq(&rtc_lock);
#ifdef CONFIG_DECSTATION
real_yrs = yrs;
yrs = 72;
/*
* We want to keep the year set to 73 until March
* for non-leap years, so that Feb, 29th is handled
* correctly.
*/
if (!leap_yr && mon < 3) {
real_yrs--;
yrs = 73;
}
#endif
/* These limits and adjustments are independant of
* whether the chip is in binary mode or not.
*/
if (yrs > 169) {
spin_unlock_irq(&rtc_lock);
return -EINVAL;
}
if (yrs >= 100)
yrs -= 100;
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
|| RTC_ALWAYS_BCD) {
BIN_TO_BCD(sec);
BIN_TO_BCD(min);
BIN_TO_BCD(hrs);
BIN_TO_BCD(day);
BIN_TO_BCD(mon);
BIN_TO_BCD(yrs);
}
save_control = CMOS_READ(RTC_CONTROL);
CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
#ifdef CONFIG_DECSTATION
CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
#endif
CMOS_WRITE(yrs, RTC_YEAR);
CMOS_WRITE(mon, RTC_MONTH);
CMOS_WRITE(day, RTC_DAY_OF_MONTH);
CMOS_WRITE(hrs, RTC_HOURS);
CMOS_WRITE(min, RTC_MINUTES);
CMOS_WRITE(sec, RTC_SECONDS);
CMOS_WRITE(save_control, RTC_CONTROL);
CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
spin_unlock_irq(&rtc_lock);
return 0;
}
#if RTC_IRQ
case RTC_IRQP_READ: /* Read the periodic IRQ rate. */
{
return put_user(rtc_freq, (unsigned long *)arg);
}
case RTC_IRQP_SET: /* Set periodic IRQ rate. */
{
int tmp = 0;
unsigned char val;
/*
* The max we can do is 8192Hz.
*/
if ((arg < 2) || (arg > 8192))
return -EINVAL;
/*
* We don't really want Joe User generating more
* than 64Hz of interrupts on a multi-user machine.
*/
if ((arg > 64) && (!capable(CAP_SYS_RESOURCE)))
return -EACCES;
while (arg > (1<<tmp))
tmp++;
/*
* Check that the input was really a power of 2.
*/
if (arg != (1<<tmp))
return -EINVAL;
spin_lock_irq(&rtc_lock);
rtc_freq = arg;
val = CMOS_READ(RTC_FREQ_SELECT) & 0xf0;
val |= (16 - tmp);
CMOS_WRITE(val, RTC_FREQ_SELECT);
spin_unlock_irq(&rtc_lock);
return 0;
}
#endif
case RTC_EPOCH_READ: /* Read the epoch. */
{
return put_user (epoch, (unsigned long *)arg);
}
case RTC_EPOCH_SET: /* Set the epoch. */
{
/*
* There were no RTC clocks before 1900.
*/
if (arg < 1900)
return -EINVAL;
if (!capable(CAP_SYS_TIME))
return -EACCES;
epoch = arg;
return 0;
}
default:
return -EINVAL;
}
return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
}
/*
* We enforce only one user at a time here with the open/close.
* Also clear the previous interrupt data on an open, and clean
* up things on a close.
*/
/* We use rtc_lock to protect against concurrent opens. So the BKL is not
* needed here. Or anywhere else in this driver. */
static int rtc_open(struct inode *inode, struct file *file)
{
spin_lock_irq (&rtc_lock);
if(rtc_status & RTC_IS_OPEN)
goto out_busy;
rtc_status |= RTC_IS_OPEN;
rtc_irq_data = 0;
spin_unlock_irq (&rtc_lock);
return 0;
out_busy:
spin_unlock_irq (&rtc_lock);
return -EBUSY;
}
static int rtc_fasync (int fd, struct file *filp, int on)
{
return fasync_helper (fd, filp, on, &rtc_async_queue);
}
static int rtc_release(struct inode *inode, struct file *file)
{
#if RTC_IRQ
unsigned char tmp;
if (rtc_has_irq == 0)
goto no_irq;
/*
* Turn off all interrupts once the device is no longer
* in use, and clear the data.
*/
spin_lock_irq(&rtc_lock);
tmp = CMOS_READ(RTC_CONTROL);
tmp &= ~RTC_PIE;
tmp &= ~RTC_AIE;
tmp &= ~RTC_UIE;
CMOS_WRITE(tmp, RTC_CONTROL);
CMOS_READ(RTC_INTR_FLAGS);
if (rtc_status & RTC_TIMER_ON) {
rtc_status &= ~RTC_TIMER_ON;
del_timer(&rtc_irq_timer);
}
spin_unlock_irq(&rtc_lock);
if (file->f_flags & FASYNC) {
rtc_fasync (-1, file, 0);
}
no_irq:
#endif
spin_lock_irq (&rtc_lock);
rtc_irq_data = 0;
spin_unlock_irq (&rtc_lock);
/* No need for locking -- nobody else can do anything until this rmw is
* committed, and no timer is running. */
rtc_status &= ~RTC_IS_OPEN;
return 0;
}
#if RTC_IRQ
/* Called without the kernel lock - fine */
static unsigned int rtc_poll(struct file *file, poll_table *wait)
{
unsigned long l;
if (rtc_has_irq == 0)
return 0;
poll_wait(file, &rtc_wait, wait);
spin_lock_irq (&rtc_lock);
l = rtc_irq_data;
spin_unlock_irq (&rtc_lock);
if (l != 0)
return POLLIN | POLLRDNORM;
return 0;
}
#endif
/*
* The various file operations we support.
*/
static struct file_operations rtc_fops = {
owner: THIS_MODULE,
llseek: no_llseek,
read: rtc_read,
#if RTC_IRQ
poll: rtc_poll,
#endif
ioctl: rtc_ioctl,
open: rtc_open,
release: rtc_release,
fasync: rtc_fasync,
};
static struct miscdevice rtc_dev=
{
RTC_MINOR,
"rtc",
&rtc_fops
};
static int __init rtc_init(void)
{
#if defined(__alpha__) || defined(__mips__)
unsigned int year, ctrl;
unsigned long uip_watchdog;
char *guess = NULL;
#endif
#ifdef __sparc__
struct linux_ebus *ebus;
struct linux_ebus_device *edev;
#ifdef __sparc_v9__
struct isa_bridge *isa_br;
struct isa_device *isa_dev;
#endif
#endif
#ifdef __sparc__
for_each_ebus(ebus) {
for_each_ebusdev(edev, ebus) {
if(strcmp(edev->prom_name, "rtc") == 0) {
rtc_port = edev->resource[0].start;
rtc_irq = edev->irqs[0];
goto found;
}
}
}
#ifdef __sparc_v9__
for_each_isa(isa_br) {
for_each_isadev(isa_dev, isa_br) {
if (strcmp(isa_dev->prom_name, "rtc") == 0) {
rtc_port = isa_dev->resource.start;
rtc_irq = isa_dev->irq;
goto found;
}
}
}
#endif
printk(KERN_ERR "rtc_init: no PC rtc found\n");
return -EIO;
found:
if (rtc_irq == PCI_IRQ_NONE) {
rtc_has_irq = 0;
goto no_irq;
}
/*
* XXX Interrupt pin #7 in Espresso is shared between RTC and
* PCI Slot 2 INTA# (and some INTx# in Slot 1). SA_INTERRUPT here
* is asking for trouble with add-on boards. Change to SA_SHIRQ.
*/
if (request_irq(rtc_irq, rtc_interrupt, SA_INTERRUPT, "rtc", (void *)&rtc_port)) {
/*
* Standard way for sparc to print irq's is to use
* __irq_itoa(). I think for EBus it's ok to use %d.
*/
printk(KERN_ERR "rtc: cannot register IRQ %d\n", rtc_irq);
return -EIO;
}
no_irq:
#else
if (check_region (RTC_PORT (0), RTC_IO_EXTENT))
{
printk(KERN_ERR "rtc: I/O port %d is not free.\n", RTC_PORT (0));
return -EIO;
}
#if RTC_IRQ
if(request_irq(RTC_IRQ, rtc_interrupt, SA_INTERRUPT, "rtc", NULL))
{
/* Yeah right, seeing as irq 8 doesn't even hit the bus. */
printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
return -EIO;
}
#endif
request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
#endif /* __sparc__ vs. others */
misc_register(&rtc_dev);
create_proc_read_entry ("driver/rtc", 0, 0, rtc_read_proc, NULL);
#if defined(__alpha__) || defined(__mips__)
rtc_freq = HZ;
/* Each operating system on an Alpha uses its own epoch.
Let's try to guess which one we are using now. */
uip_watchdog = jiffies;
if (rtc_is_updating() != 0)
while (jiffies - uip_watchdog < 2*HZ/100) {
barrier();
cpu_relax();
}
spin_lock_irq(&rtc_lock);
year = CMOS_READ(RTC_YEAR);
ctrl = CMOS_READ(RTC_CONTROL);
spin_unlock_irq(&rtc_lock);
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
BCD_TO_BIN(year); /* This should never happen... */
if (year < 20) {
epoch = 2000;
guess = "SRM (post-2000)";
} else if (year >= 20 && year < 48) {
epoch = 1980;
guess = "ARC console";
} else if (year >= 48 && year < 72) {
epoch = 1952;
guess = "Digital UNIX";
#if defined(__mips__)
} else if (year >= 72 && year < 74) {
epoch = 2000;
guess = "Digital DECstation";
#else
} else if (year >= 70) {
epoch = 1900;
guess = "Standard PC (1900)";
#endif
}
if (guess)
printk(KERN_INFO "rtc: %s epoch (%lu) detected\n", guess, epoch);
#endif
#if RTC_IRQ
if (rtc_has_irq == 0)
goto no_irq2;
init_timer(&rtc_irq_timer);
rtc_irq_timer.function = rtc_dropped_irq;
spin_lock_irq(&rtc_lock);
/* Initialize periodic freq. to CMOS reset default, which is 1024Hz */
CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) & 0xF0) | 0x06), RTC_FREQ_SELECT);
spin_unlock_irq(&rtc_lock);
rtc_freq = 1024;
no_irq2:
#endif
printk(KERN_INFO "Real Time Clock Driver v" RTC_VERSION "\n");
return 0;
}
static void __exit rtc_exit (void)
{
remove_proc_entry ("driver/rtc", NULL);
misc_deregister(&rtc_dev);
#ifdef __sparc__
if (rtc_has_irq)
free_irq (rtc_irq, &rtc_port);
#else
release_region (RTC_PORT (0), RTC_IO_EXTENT);
#if RTC_IRQ
if (rtc_has_irq)
free_irq (RTC_IRQ, NULL);
#endif
#endif /* __sparc__ */
}
module_init(rtc_init);
module_exit(rtc_exit);
EXPORT_NO_SYMBOLS;
#if RTC_IRQ
/*
* At IRQ rates >= 4096Hz, an interrupt may get lost altogether.
* (usually during an IDE disk interrupt, with IRQ unmasking off)
* Since the interrupt handler doesn't get called, the IRQ status
* byte doesn't get read, and the RTC stops generating interrupts.
* A timer is set, and will call this function if/when that happens.
* To get it out of this stalled state, we just read the status.
* At least a jiffy of interrupts (rtc_freq/HZ) will have been lost.
* (You *really* shouldn't be trying to use a non-realtime system
* for something that requires a steady > 1KHz signal anyways.)
*/
static void rtc_dropped_irq(unsigned long data)
{
unsigned long freq;
spin_lock_irq (&rtc_lock);
/* Just in case someone disabled the timer from behind our back... */
if (rtc_status & RTC_TIMER_ON)
mod_timer(&rtc_irq_timer, jiffies + HZ/rtc_freq + 2*HZ/100);
rtc_irq_data += ((rtc_freq/HZ)<<8);
rtc_irq_data &= ~0xff;
rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0); /* restart */
freq = rtc_freq;
spin_unlock_irq(&rtc_lock);
printk(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n", freq);
/* Now we have new data */
wake_up_interruptible(&rtc_wait);
kill_fasync (&rtc_async_queue, SIGIO, POLL_IN);
}
#endif
/*
* Info exported via "/proc/driver/rtc".
*/
static int rtc_proc_output (char *buf)
{
#define YN(bit) ((ctrl & bit) ? "yes" : "no")
#define NY(bit) ((ctrl & bit) ? "no" : "yes")
char *p;
struct rtc_time tm;
unsigned char batt, ctrl;
unsigned long freq;
spin_lock_irq(&rtc_lock);
batt = CMOS_READ(RTC_VALID) & RTC_VRT;
ctrl = CMOS_READ(RTC_CONTROL);
freq = rtc_freq;
spin_unlock_irq(&rtc_lock);
p = buf;
get_rtc_time(&tm);
/*
* There is no way to tell if the luser has the RTC set for local
* time or for Universal Standard Time (GMT). Probably local though.
*/
p += sprintf(p,
"rtc_time\t: %02d:%02d:%02d\n"
"rtc_date\t: %04d-%02d-%02d\n"
"rtc_epoch\t: %04lu\n",
tm.tm_hour, tm.tm_min, tm.tm_sec,
tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);
get_rtc_alm_time(&tm);
/*
* We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
* match any value for that particular field. Values that are
* greater than a valid time, but less than 0xc0 shouldn't appear.
*/
p += sprintf(p, "alarm\t\t: ");
if (tm.tm_hour <= 24)
p += sprintf(p, "%02d:", tm.tm_hour);
else
p += sprintf(p, "**:");
if (tm.tm_min <= 59)
p += sprintf(p, "%02d:", tm.tm_min);
else
p += sprintf(p, "**:");
if (tm.tm_sec <= 59)
p += sprintf(p, "%02d\n", tm.tm_sec);
else
p += sprintf(p, "**\n");
p += sprintf(p,
"DST_enable\t: %s\n"
"BCD\t\t: %s\n"
"24hr\t\t: %s\n"
"square_wave\t: %s\n"
"alarm_IRQ\t: %s\n"
"update_IRQ\t: %s\n"
"periodic_IRQ\t: %s\n"
"periodic_freq\t: %ld\n"
"batt_status\t: %s\n",
YN(RTC_DST_EN),
NY(RTC_DM_BINARY),
YN(RTC_24H),
YN(RTC_SQWE),
YN(RTC_AIE),
YN(RTC_UIE),
YN(RTC_PIE),
freq,
batt ? "okay" : "dead");
return p - buf;
#undef YN
#undef NY
}
static int rtc_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int len = rtc_proc_output (page);
if (len <= off+count) *eof = 1;
*start = page + off;
len -= off;
if (len>count) len = count;
if (len<0) len = 0;
return len;
}
/*
* Returns true if a clock update is in progress
*/
/* FIXME shouldn't this be above rtc_init to make it fully inlined? */
static inline unsigned char rtc_is_updating(void)
{
unsigned char uip;
spin_lock_irq(&rtc_lock);
uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
spin_unlock_irq(&rtc_lock);
return uip;
}
static void get_rtc_time(struct rtc_time *rtc_tm)
{
unsigned long uip_watchdog = jiffies;
unsigned char ctrl;
#ifdef CONFIG_DECSTATION
unsigned int real_year;
#endif
/*
* read RTC once any update in progress is done. The update
* can take just over 2ms. We wait 10 to 20ms. There is no need to
* to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
* If you need to know *exactly* when a second has started, enable
* periodic update complete interrupts, (via ioctl) and then
* immediately read /dev/rtc which will block until you get the IRQ.
* Once the read clears, read the RTC time (again via ioctl). Easy.
*/
if (rtc_is_updating() != 0)
while (jiffies - uip_watchdog < 2*HZ/100) {
barrier();
cpu_relax();
}
/*
* Only the values that we read from the RTC are set. We leave
* tm_wday, tm_yday and tm_isdst untouched. Even though the
* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
* by the RTC when initially set to a non-zero value.
*/
spin_lock_irq(&rtc_lock);
rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
#ifdef CONFIG_DECSTATION
real_year = CMOS_READ(RTC_DEC_YEAR);
#endif
ctrl = CMOS_READ(RTC_CONTROL);
spin_unlock_irq(&rtc_lock);
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{
BCD_TO_BIN(rtc_tm->tm_sec);
BCD_TO_BIN(rtc_tm->tm_min);
BCD_TO_BIN(rtc_tm->tm_hour);
BCD_TO_BIN(rtc_tm->tm_mday);
BCD_TO_BIN(rtc_tm->tm_mon);
BCD_TO_BIN(rtc_tm->tm_year);
}
#ifdef CONFIG_DECSTATION
rtc_tm->tm_year += real_year - 72;
#endif
/*
* Account for differences between how the RTC uses the values
* and how they are defined in a struct rtc_time;
*/
if ((rtc_tm->tm_year += (epoch - 1900)) <= 69)
rtc_tm->tm_year += 100;
rtc_tm->tm_mon--;
}
static void get_rtc_alm_time(struct rtc_time *alm_tm)
{
unsigned char ctrl;
/*
* Only the values that we read from the RTC are set. That
* means only tm_hour, tm_min, and tm_sec.
*/
spin_lock_irq(&rtc_lock);
alm_tm->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
ctrl = CMOS_READ(RTC_CONTROL);
spin_unlock_irq(&rtc_lock);
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{
BCD_TO_BIN(alm_tm->tm_sec);
BCD_TO_BIN(alm_tm->tm_min);
BCD_TO_BIN(alm_tm->tm_hour);
}
}
#if RTC_IRQ
/*
* Used to disable/enable interrupts for any one of UIE, AIE, PIE.
* Rumour has it that if you frob the interrupt enable/disable
* bits in RTC_CONTROL, you should read RTC_INTR_FLAGS, to
* ensure you actually start getting interrupts. Probably for
* compatibility with older/broken chipset RTC implementations.
* We also clear out any old irq data after an ioctl() that
* meddles with the interrupt enable/disable bits.
*/
static void mask_rtc_irq_bit(unsigned char bit)
{
unsigned char val;
spin_lock_irq(&rtc_lock);
val = CMOS_READ(RTC_CONTROL);
val &= ~bit;
CMOS_WRITE(val, RTC_CONTROL);
CMOS_READ(RTC_INTR_FLAGS);
rtc_irq_data = 0;
spin_unlock_irq(&rtc_lock);
}
static void set_rtc_irq_bit(unsigned char bit)
{
unsigned char val;
spin_lock_irq(&rtc_lock);
val = CMOS_READ(RTC_CONTROL);
val |= bit;
CMOS_WRITE(val, RTC_CONTROL);
CMOS_READ(RTC_INTR_FLAGS);
rtc_irq_data = 0;
spin_unlock_irq(&rtc_lock);
}
#endif
MODULE_AUTHOR("Paul Gortmaker");
MODULE_LICENSE("GPL");
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