at91_watchdog.c

linux2。4下的看门狗驱动程序源代码

/*
 *	Timer Counter interface for Linux on Atmel AT91RM9200
 *
 *	Copyright (c) 2002 Rick Bronson
 * 
 *	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.
 *

Watchdog driver.  This enables you to open a Watchdog and change the
time for the watchdog to expire.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <asm/bitops.h>
#include <asm/hardware.h>
#include <asm/irq.h>
#include <asm/arch/watchdog.h>  /* get ioctl stuff for watchdog */

extern struct watchdog_private watchdog_priv;  /* watchdog private stuff */

#define	DRIVER_VERSION	"1.00"

static int at91_watchdog_open(struct inode *inode, struct file *file)
{

	file->private_data = &watchdog_priv;
	spin_lock_init(&priv->lock1);
        MOD_INC_USE_COUNT;
        return 0;
}

static int at91_watchdog_release(struct inode *inode, struct file *file)
{
        MOD_DEC_USE_COUNT;
	return 0;
}

ssize_t at91_watchdog_write(struct file * file, const char *buf, size_t count, loff_t * ppos)
  {
#if 0  /* not sure if they want to use it this way */
  AT91PS_ST pSt;  /* pointer to the ST peripheral */
  struct at91_watchdog_ioctl_set watchdog_set;

  if (verify_area(VERIFY_READ, buf, count))
    return -EFAULT;
  if (__get_user(watchdog_set, buf))
    return -EFAULT;
  pSt = AT91C_BASE_ST;
  pSt->ST_WDMR = watchdog_set.watchdog_wdmr | AT91C_ST_RSTEN;  /* (ST) Reset Enable */
  pSt->ST_CR = AT91C_ST_WDRST;  /* (ST) Watchdog Timer Restart */
#endif
  return count;
  }

/*
 * Handle commands from user-space
 */
static int at91_watchdog_ioctl(struct inode *inode, struct file *file,
			  unsigned int cmd, unsigned long arg)
  {
  AT91PS_ST pSt;  /* pointer to the ST peripheral */
  unsigned long flags;
  struct watchdog_private *priv = (struct watchdog_private *)file->private_data;
  struct at91_watchdog_ioctl_set watchdog_set;
  struct at91_watchdog_ioctl_timer watchdog_timer;
  long long all_64bits;  /* upper 44 bits to make 64 bit timer */
  AT91_REG crtr, crtr_save;  /* saved value from AT91C_ST_CRTR (20 bits) */
  int ret = 0;

  pSt = AT91C_BASE_ST;
  switch (cmd)
    {
    case AT91_WATCHDOG_SET_WATCHDOG:  /* set and enable the watchdog */
      if (copy_from_user (&watchdog_set, (void *)arg, sizeof (watchdog_set)))
        return -EFAULT;
      pSt->ST_WDMR = watchdog_set.watchdog_wdmr | AT91C_ST_RSTEN;  /* (ST) Reset Enable */
      pSt->ST_CR = AT91C_ST_WDRST;  /* (ST) Watchdog Timer Restart */
      break;
    case AT91_WATCHDOG_GET_32768_TIMER:  /* get the timer */
      spin_lock_irqsave(&priv->lock1, flags);  /* stop int's while we
                         read values that could be changed in the interrupt */
      crtr = pSt->ST_CRTR;  /* 20 ls bits of 32768 Hz clock */
      crtr_save = priv->crtr_save;
      all_64bits = priv->upper_44bits;  /* get temp copy */
      spin_unlock_irqrestore(&priv->lock1, flags);
      if (crtr < crtr_save)  /* if wrapped, add one to upper bits */
        all_64bits += AT91C_ST_CRTV + 1;
      all_64bits |= crtr;
      ret = copy_to_user ((void *)arg, &all_64bits, sizeof (watchdog_timer)) ? -EFAULT : 0;
      break;
    default:
      ret = -EINVAL;
      break;
    }
  return ret;
  }

static struct file_operations at91_watchdog_fops = {
	owner:THIS_MODULE,
	write:at91_watchdog_write,
	ioctl:at91_watchdog_ioctl,
	open:at91_watchdog_open,
	release:at91_watchdog_release,
};

static struct miscdevice watchdog_miscdev =
{
	WATCHDOG_MINOR,
	"at91 watchdog",
	&at91_watchdog_fops
};

#/*
 * Initialize and install WATCHDOG driver
 */
static int __init at91_watchdog_init(void)
  {
  int res;
 
  res = misc_register (&watchdog_miscdev);
  if (res < 0)
    {
    printk(KERN_ERR "at91_watchdog: couldn't get a major number.\n");
    return res;
    }

  printk(KERN_INFO "AT91 Watchdog driver v" DRIVER_VERSION "\n");
  return 0;
  }

module_init(at91_watchdog_init);

MODULE_AUTHOR("Rick Bronson");
MODULE_DESCRIPTION("AT91 Timer Counter Driver (AT91_WATCHDOG)");
EXPORT_NO_SYMBOLS;