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/*
* SoftDog 0.05: A Software Watchdog Device
*
* (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
* http://www.redhat.com
*
* 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.
*
* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
* warranty for any of this software. This material is provided
* "AS-IS" and at no charge.
*
* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
*
* Software only watchdog driver. Unlike its big brother the WDT501P
* driver this won't always recover a failed machine.
*
* 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
* Modularised.
* Added soft_margin; use upon insmod to change the timer delay.
* NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
* minors.
*
* 19980911 Alan Cox
* Made SMP safe for 2.3.x
*/
#include <linux/module.h>
#include <linux/config.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#define TIMER_MARGIN 60 /* (secs) Default is 1 minute */
static int soft_margin = TIMER_MARGIN; /* in seconds */
#ifdef MODULE
MODULE_PARM(soft_margin,"i");
#endif
/*
* Our timer
*/
struct timer_list watchdog_ticktock;
static int timer_alive = 0;
/*
* If the timer expires..
*/
static void watchdog_fire(unsigned long data)
{
#ifdef ONLY_TESTING
printk(KERN_CRIT "SOFTDOG: Would Reboot.\n");
#else
printk(KERN_CRIT "SOFTDOG: Initiating system reboot.\n");
machine_restart(NULL);
printk("WATCHDOG: Reboot didn't ?????\n");
#endif
}
/*
* Allow only one person to hold it open
*/
static int softdog_open(struct inode *inode, struct file *file)
{
if(timer_alive)
return -EBUSY;
MOD_INC_USE_COUNT;
/*
* Activate timer
*/
del_timer(&watchdog_ticktock);
watchdog_ticktock.expires=jiffies + (soft_margin * HZ);
add_timer(&watchdog_ticktock);
timer_alive=1;
return 0;
}
static int softdog_release(struct inode *inode, struct file *file)
{
/*
* Shut off the timer.
* Lock it in if it's a module and we defined ...NOWAYOUT
*/
#ifndef CONFIG_WATCHDOG_NOWAYOUT
del_timer(&watchdog_ticktock);
MOD_DEC_USE_COUNT;
#endif
timer_alive=0;
return 0;
}
static void softdog_ping(void)
{
/*
* Refresh the timer.
*/
mod_timer(&watchdog_ticktock, jiffies + (soft_margin * HZ));
}
static ssize_t softdog_write(struct file *file, const char *data, size_t len, loff_t *ppos)
{
/* Can't seek (pwrite) on this device */
if (ppos != &file->f_pos)
return -ESPIPE;
/*
* Refresh the timer.
*/
if(len)
{
softdog_ping();
return 1;
}
return 0;
}
static int softdog_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
static struct watchdog_info ident=
{
0,
0,
"Software Watchdog"
};
switch(cmd)
{
default:
return -ENOIOCTLCMD;
case WDIOC_GETSUPPORT:
if(copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
return -EFAULT;
return 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0,(int *)arg);
case WDIOC_KEEPALIVE:
softdog_ping();
return 0;
}
}
static struct file_operations softdog_fops=
{
NULL, /* Seek */
NULL, /* Read */
softdog_write, /* Write */
NULL, /* Readdir */
NULL, /* Select */
softdog_ioctl, /* Ioctl */
NULL, /* MMap */
softdog_open,
NULL, /* flush */
softdog_release,
NULL,
NULL /* Fasync */
};
static struct miscdevice softdog_miscdev=
{
WATCHDOG_MINOR,
"watchdog",
&softdog_fops
};
void __init watchdog_init(void)
{
misc_register(&softdog_miscdev);
init_timer(&watchdog_ticktock);
watchdog_ticktock.function=watchdog_fire;
printk("Software Watchdog Timer: 0.05, timer margin: %d sec\n", soft_margin);
}
#ifdef MODULE
int init_module(void)
{
watchdog_init();
return 0;
}
void cleanup_module(void)
{
misc_deregister(&softdog_miscdev);
}
#endif
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