[linux-2.6-block.git] / drivers / watchdog / softdog.c

/*
 *	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);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* SoftDog 0.07: A Software Watchdog Device
	3	*
29fa0586	4	* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, All Rights Reserved.
1da177e4 LT	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*
	11	* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
	12	* warranty for any of this software. This material is provided
	13	* "AS-IS" and at no charge.
	14	*
	15	* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
	16	*
	17	* Software only watchdog driver. Unlike its big brother the WDT501P
	18	* driver this won't always recover a failed machine.
	19	*
	20	* 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
	21	* Modularised.
	22	* Added soft_margin; use upon insmod to change the timer delay.
	23	* NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
	24	* minors.
	25	*
	26	* 19980911 Alan Cox
	27	* Made SMP safe for 2.3.x
	28	*
	29	* 20011127 Joel Becker (jlbec@evilplan.org>
	30	* Added soft_noboot; Allows testing the softdog trigger without
	31	* requiring a recompile.
	32	* Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
	33	*
	34	* 20020530 Joel Becker <joel.becker@oracle.com>
	35	* Added Matt Domsch's nowayout module option.
	36	*/
	37
	38	#include <linux/module.h>
	39	#include <linux/moduleparam.h>
1da177e4 LT	40	#include <linux/types.h>
	41	#include <linux/timer.h>
	42	#include <linux/miscdevice.h>
	43	#include <linux/watchdog.h>
	44	#include <linux/fs.h>
	45	#include <linux/notifier.h>
	46	#include <linux/reboot.h>
	47	#include <linux/init.h>
4e57b681	48	#include <linux/jiffies.h>
f92d3749	49	#include <linux/uaccess.h>
1da177e4 LT	50
	51	#define PFX "SoftDog: "
	52
	53	#define TIMER_MARGIN 60 /* Default is 60 seconds */
	54	static int soft_margin = TIMER_MARGIN; /* in seconds */
	55	module_param(soft_margin, int, 0);
f92d3749 AC	56	MODULE_PARM_DESC(soft_margin,
	57	"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
	58	__MODULE_STRING(TIMER_MARGIN) ")");
1da177e4	59
4bfdf378	60	static int nowayout = WATCHDOG_NOWAYOUT;
1da177e4	61	module_param(nowayout, int, 0);
f92d3749 AC	62	MODULE_PARM_DESC(nowayout,
	63	"Watchdog cannot be stopped once started (default="
	64	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
1da177e4 LT	65
	66	#ifdef ONLY_TESTING
	67	static int soft_noboot = 1;
	68	#else
	69	static int soft_noboot = 0;
	70	#endif /* ONLY_TESTING */
	71
	72	module_param(soft_noboot, int, 0);
	73	MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
	74
	75	/*
	76	* Our timer
	77	*/
	78
	79	static void watchdog_fire(unsigned long);
	80
	81	static struct timer_list watchdog_ticktock =
	82	TIMER_INITIALIZER(watchdog_fire, 0, 0);
1cc77248	83	static unsigned long driver_open, orphan_timer;
1da177e4 LT	84	static char expect_close;
	85
	86
	87	/*
	88	* If the timer expires..
	89	*/
	90
	91	static void watchdog_fire(unsigned long data)
	92	{
1cc77248 CE	93	if (test_and_clear_bit(0, &orphan_timer))
	94	module_put(THIS_MODULE);
	95
1da177e4 LT	96	if (soft_noboot)
1da177e4 LT	97	printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
f92d3749	98	else {
1da177e4	99	printk(KERN_CRIT PFX "Initiating system reboot.\n");
479d0f41	100	emergency_restart();
1da177e4 LT	101	printk(KERN_CRIT PFX "Reboot didn't ?????\n");
	102	}
	103	}
	104
	105	/*
	106	* Softdog operations
	107	*/
	108
	109	static int softdog_keepalive(void)
	110	{
	111	mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
	112	return 0;
	113	}
	114
	115	static int softdog_stop(void)
	116	{
	117	del_timer(&watchdog_ticktock);
	118	return 0;
	119	}
	120
	121	static int softdog_set_heartbeat(int t)
	122	{
	123	if ((t < 0x0001) \|\| (t > 0xFFFF))
	124	return -EINVAL;
	125
	126	soft_margin = t;
	127	return 0;
	128	}
	129
	130	/*
	131	* /dev/watchdog handling
	132	*/
	133
	134	static int softdog_open(struct inode inode, struct file file)
	135	{
1cc77248	136	if (test_and_set_bit(0, &driver_open))
1da177e4	137	return -EBUSY;
1cc77248	138	if (!test_and_clear_bit(0, &orphan_timer))
1da177e4 LT	139	__module_get(THIS_MODULE);
	140	/*
	141	* Activate timer
	142	*/
	143	softdog_keepalive();
	144	return nonseekable_open(inode, file);
	145	}
	146
	147	static int softdog_release(struct inode inode, struct file file)
	148	{
	149	/*
	150	* Shut off the timer.
	151	* Lock it in if it's a module and we set nowayout
	152	*/
	153	if (expect_close == 42) {
	154	softdog_stop();
1cc77248	155	module_put(THIS_MODULE);
1da177e4	156	} else {
f92d3749 AC	157	printk(KERN_CRIT PFX
f92d3749 AC	158	"Unexpected close, not stopping watchdog!\n");
1cc77248	159	set_bit(0, &orphan_timer);
1da177e4 LT	160	softdog_keepalive();
1da177e4 LT	161	}
1cc77248	162	clear_bit(0, &driver_open);
1da177e4 LT	163	expect_close = 0;
	164	return 0;
	165	}
	166
f92d3749 AC	167	static ssize_t softdog_write(struct file file, const char __user data,
f92d3749 AC	168	size_t len, loff_t *ppos)
1da177e4 LT	169	{
	170	/*
	171	* Refresh the timer.
	172	*/
f92d3749	173	if (len) {
1da177e4 LT	174	if (!nowayout) {
	175	size_t i;
	176
	177	/* In case it was set long ago */
	178	expect_close = 0;
	179
	180	for (i = 0; i != len; i++) {
	181	char c;
	182
	183	if (get_user(c, data + i))
	184	return -EFAULT;
	185	if (c == 'V')
	186	expect_close = 42;
	187	}
	188	}
	189	softdog_keepalive();
	190	}
	191	return len;
	192	}
	193
f92d3749 AC	194	static long softdog_ioctl(struct file *file, unsigned int cmd,
f92d3749 AC	195	unsigned long arg)
1da177e4 LT	196	{
	197	void __user argp = (void __user )arg;
	198	int __user *p = argp;
	199	int new_margin;
f92d3749	200	static const struct watchdog_info ident = {
1da177e4 LT	201	.options = WDIOF_SETTIMEOUT \|
	202	WDIOF_KEEPALIVEPING \|
	203	WDIOF_MAGICCLOSE,
	204	.firmware_version = 0,
	205	.identity = "Software Watchdog",
	206	};
	207	switch (cmd) {
f92d3749 AC	208	case WDIOC_GETSUPPORT:
	209	return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	210	case WDIOC_GETSTATUS:
	211	case WDIOC_GETBOOTSTATUS:
	212	return put_user(0, p);
	213	case WDIOC_KEEPALIVE:
	214	softdog_keepalive();
	215	return 0;
	216	case WDIOC_SETTIMEOUT:
	217	if (get_user(new_margin, p))
	218	return -EFAULT;
	219	if (softdog_set_heartbeat(new_margin))
	220	return -EINVAL;
	221	softdog_keepalive();
	222	/* Fall */
	223	case WDIOC_GETTIMEOUT:
	224	return put_user(soft_margin, p);
0c06090c WVS	225	default:
0c06090c WVS	226	return -ENOTTY;
1da177e4 LT	227	}
	228	}
	229
	230	/*
	231	* Notifier for system down
	232	*/
	233
	234	static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
	235	void *unused)
	236	{
f92d3749	237	if (code == SYS_DOWN \|\| code == SYS_HALT)
1da177e4 LT	238	/* Turn the WDT off */
1da177e4 LT	239	softdog_stop();
1da177e4 LT	240	return NOTIFY_DONE;
	241	}
	242
	243	/*
	244	* Kernel Interfaces
	245	*/
	246
62322d25	247	static const struct file_operations softdog_fops = {
1da177e4 LT	248	.owner = THIS_MODULE,
	249	.llseek = no_llseek,
	250	.write = softdog_write,
f92d3749	251	.unlocked_ioctl = softdog_ioctl,
1da177e4 LT	252	.open = softdog_open,
	253	.release = softdog_release,
	254	};
	255
	256	static struct miscdevice softdog_miscdev = {
	257	.minor = WATCHDOG_MINOR,
	258	.name = "watchdog",
	259	.fops = &softdog_fops,
	260	};
	261
	262	static struct notifier_block softdog_notifier = {
	263	.notifier_call = softdog_notify_sys,
	264	};
	265
	266	static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
	267
	268	static int __init watchdog_init(void)
	269	{
	270	int ret;
	271
f92d3749 AC	272	/* Check that the soft_margin value is within it's range;
f92d3749 AC	273	if not reset to the default */
1da177e4 LT	274	if (softdog_set_heartbeat(soft_margin)) {
1da177e4 LT	275	softdog_set_heartbeat(TIMER_MARGIN);
f92d3749 AC	276	printk(KERN_INFO PFX
f92d3749 AC	277	"soft_margin must be 0 < soft_margin < 65536, using %d\n",
1da177e4 LT	278	TIMER_MARGIN);
	279	}
	280
	281	ret = register_reboot_notifier(&softdog_notifier);
	282	if (ret) {
f92d3749 AC	283	printk(KERN_ERR PFX
f92d3749 AC	284	"cannot register reboot notifier (err=%d)\n", ret);
1da177e4 LT	285	return ret;
	286	}
	287
	288	ret = misc_register(&softdog_miscdev);
	289	if (ret) {
f92d3749 AC	290	printk(KERN_ERR PFX
	291	"cannot register miscdev on minor=%d (err=%d)\n",
	292	WATCHDOG_MINOR, ret);
1da177e4 LT	293	unregister_reboot_notifier(&softdog_notifier);
	294	return ret;
	295	}
	296
	297	printk(banner, soft_noboot, soft_margin, nowayout);
	298
	299	return 0;
	300	}
	301
	302	static void __exit watchdog_exit(void)
	303	{
	304	misc_deregister(&softdog_miscdev);
	305	unregister_reboot_notifier(&softdog_notifier);
	306	}
	307
	308	module_init(watchdog_init);
	309	module_exit(watchdog_exit);
	310
	311	MODULE_AUTHOR("Alan Cox");
	312	MODULE_DESCRIPTION("Software Watchdog Device Driver");
	313	MODULE_LICENSE("GPL");
	314	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);