/*
* SoftDog 0.07: A Software Watchdog Device
*
* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
* All Rights Reserved.
*
* 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
*
* 20011127 Joel Becker (jlbec@evilplan.org>
* Added soft_noboot; Allows testing the softdog trigger without
* requiring a recompile.
* Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
*
* 20020530 Joel Becker <joel.becker@oracle.com>
* Added Matt Domsch's nowayout module option.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/uaccess.h>
#define PFX "SoftDog: "
#define TIMER_MARGIN 60 /* Default is 60 seconds */
static int soft_margin = TIMER_MARGIN; /* in seconds */
module_param(soft_margin, int, 0);
MODULE_PARM_DESC(soft_margin,
"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
__MODULE_STRING(TIMER_MARGIN) ")");
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
#ifdef ONLY_TESTING
static int soft_noboot = 1;
#else
static int soft_noboot = 0;
#endif /* ONLY_TESTING */
module_param(soft_noboot, int, 0);
MODULE_PARM_DESC(soft_noboot,
"Softdog action, set to 1 to ignore reboots, 0 to reboot "
"(default depends on ONLY_TESTING)");
/*
* Our timer
*/
static void watchdog_fire(unsigned long);
static struct timer_list watchdog_ticktock =
TIMER_INITIALIZER(watchdog_fire, 0, 0);
static unsigned long driver_open, orphan_timer;
static char expect_close;
/*
* If the timer expires..
*/
static void watchdog_fire(unsigned long data)
{
if (test_and_clear_bit(0, &orphan_timer))
module_put(THIS_MODULE);
if (soft_noboot)
printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
else {
printk(KERN_CRIT PFX "Initiating system reboot.\n");
emergency_restart();
printk(KERN_CRIT PFX "Reboot didn't ?????\n");
}
}
/*
* Softdog operations
*/
static int softdog_keepalive(void)
{
mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
return 0;
}
static int softdog_stop(void)
{
del_timer(&watchdog_ticktock);
return 0;
}
static int softdog_set_heartbeat(int t)
{
if ((t < 0x0001) || (t > 0xFFFF))
return -EINVAL;
soft_margin = t;
return 0;
}
/*
* /dev/watchdog handling
*/
static int softdog_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &driver_open))
return -EBUSY;
if (!test_and_clear_bit(0, &orphan_timer))
__module_get(THIS_MODULE);
/*
* Activate timer
*/
softdog_keepalive();
return nonseekable_open(inode, file);
}
static int softdog_release(struct inode *inode, struct file *file)
{
/*
* Shut off the timer.
* Lock it in if it's a module and we set nowayout
*/
if (expect_close == 42) {
softdog_stop();
module_put(THIS_MODULE);
} else {
printk(KERN_CRIT PFX
"Unexpected close, not stopping watchdog!\n");
set_bit(0, &orphan_timer);
softdog_keepalive();
}
clear_bit(0, &driver_open);
expect_close = 0;
return 0;
}
static ssize_t softdog_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
/*
* Refresh the timer.
*/
if (len) {
if (!nowayout) {
size_t i;
/* In case it was set long ago */
expect_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
softdog_keepalive();
}
return len;
}
static long softdog_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
int new_margin;
static const struct watchdog_info ident = {
.options = WDIOF_SETTIMEOUT |
WDIOF_KEEPALIVEPING |
WDIOF_MAGICCLOSE,
.firmware_version = 0,
.identity = "Software Watchdog",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_KEEPALIVE:
softdog_keepalive();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, p))
return -EFAULT;
if (softdog_set_heartbeat(new_margin))
return -EINVAL;
softdog_keepalive();
/* Fall */
case WDIOC_GETTIMEOUT:
return put_user(soft_margin, p);
default:
return -ENOTTY;
}
}
/*
* Notifier for system down
*/
static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT)
/* Turn the WDT off */
softdog_stop();
return NOTIFY_DONE;
}
/*
* Kernel Interfaces
*/
static const struct file_operations softdog_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = softdog_write,
.unlocked_ioctl = softdog_ioctl,
.open = softdog_open,
.release = softdog_release,
};
static struct miscdevice softdog_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &softdog_fops,
};
static struct notifier_block softdog_notifier = {
.notifier_call = softdog_notify_sys,
};
static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 "
"initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
static int __init watchdog_init(void)
{
int ret;
/* Check that the soft_margin value is within it's range;
if not reset to the default */
if (softdog_set_heartbeat(soft_margin)) {
softdog_set_heartbeat(TIMER_MARGIN);
printk(KERN_INFO PFX
"soft_margin must be 0 < soft_margin < 65536, using %d\n",
TIMER_MARGIN);
}
ret = register_reboot_notifier(&softdog_notifier);
if (ret) {
printk(KERN_ERR PFX
"cannot register reboot notifier (err=%d)\n", ret);
return ret;
}
ret = misc_register(&softdog_miscdev);
if (ret) {
printk(KERN_ERR PFX
"cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
unregister_reboot_notifier(&softdog_notifier);
return ret;
}
printk(banner, soft_noboot, soft_margin, nowayout);
return 0;
}
static void __exit watchdog_exit(void)
{
misc_deregister(&softdog_miscdev);
unregister_reboot_notifier(&softdog_notifier);
}
module_init(watchdog_init);
module_exit(watchdog_exit);
MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("Software Watchdog Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
