drivers/char/watchdog/softdog.c - kernel/msm - Gitiles

 /*
  *	SoftDog	0.07:	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
  *
  *  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 <asm/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=CONFIG_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 int softdog_ioctl(struct inode *inode, struct file *file,
 	unsigned int cmd, unsigned long arg)
 {
 	void __user *argp = (void __user *)arg;
 	int __user *p = argp;
 	int new_margin;
 	static struct watchdog_info ident = {
 		.options =		WDIOF_SETTIMEOUT |
 					WDIOF_KEEPALIVEPING |
 					WDIOF_MAGICCLOSE,
 		.firmware_version =	0,
 		.identity =		"Software Watchdog",
 	};
 	switch (cmd) {
 		default:
 			return -ENOIOCTLCMD;
 		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);
 	}
 }

 /*
  *	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,
 	.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 value 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);
	/*
	* SoftDog 0.07: 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
	*
	* 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 <asm/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=CONFIG_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 int softdog_ioctl(struct inode inode, struct file file,
	unsigned int cmd, unsigned long arg)
	{
	void __user argp = (void __user )arg;
	int __user *p = argp;
	int new_margin;
	static struct watchdog_info ident = {
	.options = WDIOF_SETTIMEOUT \|
	WDIOF_KEEPALIVEPING \|
	WDIOF_MAGICCLOSE,
	.firmware_version = 0,
	.identity = "Software Watchdog",
	};
	switch (cmd) {
	default:
	return -ENOIOCTLCMD;
	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);
	}
	}

	/*
	* 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,
	.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 value 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);