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/*
* SoftDog: 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#define TIMER_MARGIN 60 /* Default is 60 seconds */
static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
module_param(soft_margin, uint, 0);
MODULE_PARM_DESC(soft_margin,
"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
__MODULE_STRING(TIMER_MARGIN) ")");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static int soft_noboot = 0;
module_param(soft_noboot, int, 0);
MODULE_PARM_DESC(soft_noboot,
"Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
static int soft_panic;
module_param(soft_panic, int, 0);
MODULE_PARM_DESC(soft_panic,
"Softdog action, set to 1 to panic, 0 to reboot (default=0)");
/*
* Our timer
*/
static void watchdog_fire(unsigned long);
static struct timer_list watchdog_ticktock =
TIMER_INITIALIZER(watchdog_fire, 0, 0);
/*
* If the timer expires..
*/
static void watchdog_fire(unsigned long data)
{
if (soft_noboot)
pr_crit("Triggered - Reboot ignored\n");
else if (soft_panic) {
pr_crit("Initiating panic\n");
panic("Software Watchdog Timer expired");
} else {
pr_crit("Initiating system reboot\n");
emergency_restart();
pr_crit("Reboot didn't ?????\n");
}
}
/*
* Softdog operations
*/
static int softdog_ping(struct watchdog_device *w)
{
mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
return 0;
}
static int softdog_stop(struct watchdog_device *w)
{
del_timer(&watchdog_ticktock);
return 0;
}
static int softdog_set_timeout(struct watchdog_device *w, unsigned int t)
{
w->timeout = t;
return 0;
}
/*
* 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(NULL);
return NOTIFY_DONE;
}
/*
* Kernel Interfaces
*/
static struct notifier_block softdog_notifier = {
.notifier_call = softdog_notify_sys,
};
static struct watchdog_info softdog_info = {
.identity = "Software Watchdog",
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
};
static struct watchdog_ops softdog_ops = {
.owner = THIS_MODULE,
.start = softdog_ping,
.stop = softdog_stop,
.set_timeout = softdog_set_timeout,
};
static struct watchdog_device softdog_dev = {
.info = &softdog_info,
.ops = &softdog_ops,
.min_timeout = 1,
.max_timeout = 0xFFFF
};
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 (soft_margin < 1 || soft_margin > 65535) {
pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
TIMER_MARGIN);
return -EINVAL;
}
softdog_dev.timeout = soft_margin;
watchdog_set_nowayout(&softdog_dev, nowayout);
ret = register_reboot_notifier(&softdog_notifier);
if (ret) {
pr_err("cannot register reboot notifier (err=%d)\n", ret);
return ret;
}
ret = watchdog_register_device(&softdog_dev);
if (ret) {
unregister_reboot_notifier(&softdog_notifier);
return ret;
}
pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
soft_noboot, soft_margin, soft_panic, nowayout);
return 0;
}
static void __exit watchdog_exit(void)
{
watchdog_unregister_device(&softdog_dev);
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);
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