[deliverable/linux.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.
 */

#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/fs.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>

#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)");

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);
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)
		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_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 {
		pr_crit("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 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);
		pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
			TIMER_MARGIN);
	}

	ret = register_reboot_notifier(&softdog_notifier);
	if (ret) {
		pr_err("cannot register reboot notifier (err=%d)\n", ret);
		return ret;
	}

	ret = misc_register(&softdog_miscdev);
	if (ret) {
		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
		       WATCHDOG_MINOR, ret);
		unregister_reboot_notifier(&softdog_notifier);
		return ret;
	}

	pr_info("Software Watchdog Timer: 0.07 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)
{
	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	*
143a2e54 WVS	4	* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
143a2e54 WVS	5	* All Rights Reserved.
1da177e4 LT	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License
	9	* as published by the Free Software Foundation; either version
	10	* 2 of the License, or (at your option) any later version.
	11	*
	12	* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
	13	* warranty for any of this software. This material is provided
	14	* "AS-IS" and at no charge.
	15	*
	16	* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
	17	*
	18	* Software only watchdog driver. Unlike its big brother the WDT501P
	19	* driver this won't always recover a failed machine.
	20	*
	21	* 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
	22	* Modularised.
	23	* Added soft_margin; use upon insmod to change the timer delay.
	24	* NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
	25	* minors.
	26	*
	27	* 19980911 Alan Cox
	28	* Made SMP safe for 2.3.x
	29	*
	30	* 20011127 Joel Becker (jlbec@evilplan.org>
	31	* Added soft_noboot; Allows testing the softdog trigger without
	32	* requiring a recompile.
	33	* Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
	34	*
	35	* 20020530 Joel Becker <joel.becker@oracle.com>
143a2e54	36	* Added Matt Domsch's nowayout module option.
1da177e4 LT	37	*/
1da177e4 LT	38
27c766aa JP	39	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27c766aa JP	40
1da177e4 LT	41	#include <linux/module.h>
1da177e4 LT	42	#include <linux/moduleparam.h>
1da177e4 LT	43	#include <linux/types.h>
	44	#include <linux/timer.h>
	45	#include <linux/miscdevice.h>
	46	#include <linux/watchdog.h>
	47	#include <linux/fs.h>
	48	#include <linux/notifier.h>
	49	#include <linux/reboot.h>
	50	#include <linux/init.h>
4e57b681	51	#include <linux/jiffies.h>
f92d3749	52	#include <linux/uaccess.h>
7fff4beb	53	#include <linux/kernel.h>
1da177e4	54
1da177e4 LT	55	#define TIMER_MARGIN 60 /* Default is 60 seconds */
	56	static int soft_margin = TIMER_MARGIN; /* in seconds */
	57	module_param(soft_margin, int, 0);
f92d3749 AC	58	MODULE_PARM_DESC(soft_margin,
	59	"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
	60	__MODULE_STRING(TIMER_MARGIN) ")");
1da177e4	61
4bfdf378	62	static int nowayout = WATCHDOG_NOWAYOUT;
1da177e4	63	module_param(nowayout, int, 0);
f92d3749 AC	64	MODULE_PARM_DESC(nowayout,
	65	"Watchdog cannot be stopped once started (default="
	66	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
1da177e4 LT	67
	68	#ifdef ONLY_TESTING
	69	static int soft_noboot = 1;
	70	#else
	71	static int soft_noboot = 0;
	72	#endif /* ONLY_TESTING */
	73
	74	module_param(soft_noboot, int, 0);
a77dba7e WVS	75	MODULE_PARM_DESC(soft_noboot,
	76	"Softdog action, set to 1 to ignore reboots, 0 to reboot "
	77	"(default depends on ONLY_TESTING)");
1da177e4	78
7fff4beb AJ	79	static int soft_panic;
	80	module_param(soft_panic, int, 0);
	81	MODULE_PARM_DESC(soft_panic,
	82	"Softdog action, set to 1 to panic, 0 to reboot (default=0)");
	83
1da177e4 LT	84	/*
	85	* Our timer
	86	*/
	87
	88	static void watchdog_fire(unsigned long);
	89
	90	static struct timer_list watchdog_ticktock =
	91	TIMER_INITIALIZER(watchdog_fire, 0, 0);
1cc77248	92	static unsigned long driver_open, orphan_timer;
1da177e4 LT	93	static char expect_close;
	94
	95
	96	/*
	97	* If the timer expires..
	98	*/
	99
	100	static void watchdog_fire(unsigned long data)
	101	{
1cc77248 CE	102	if (test_and_clear_bit(0, &orphan_timer))
	103	module_put(THIS_MODULE);
	104
1da177e4	105	if (soft_noboot)
27c766aa	106	pr_crit("Triggered - Reboot ignored\n");
7fff4beb	107	else if (soft_panic) {
27c766aa JP	108	pr_crit("Initiating panic\n");
27c766aa JP	109	panic("Software Watchdog Timer expired");
7fff4beb	110	} else {
27c766aa	111	pr_crit("Initiating system reboot\n");
479d0f41	112	emergency_restart();
27c766aa	113	pr_crit("Reboot didn't ?????\n");
1da177e4 LT	114	}
	115	}
	116
	117	/*
	118	* Softdog operations
	119	*/
	120
	121	static int softdog_keepalive(void)
	122	{
	123	mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
	124	return 0;
	125	}
	126
	127	static int softdog_stop(void)
	128	{
	129	del_timer(&watchdog_ticktock);
	130	return 0;
	131	}
	132
	133	static int softdog_set_heartbeat(int t)
	134	{
	135	if ((t < 0x0001) \|\| (t > 0xFFFF))
	136	return -EINVAL;
	137
	138	soft_margin = t;
	139	return 0;
	140	}
	141
	142	/*
	143	* /dev/watchdog handling
	144	*/
	145
	146	static int softdog_open(struct inode inode, struct file file)
	147	{
1cc77248	148	if (test_and_set_bit(0, &driver_open))
1da177e4	149	return -EBUSY;
1cc77248	150	if (!test_and_clear_bit(0, &orphan_timer))
1da177e4 LT	151	__module_get(THIS_MODULE);
	152	/*
	153	* Activate timer
	154	*/
	155	softdog_keepalive();
	156	return nonseekable_open(inode, file);
	157	}
	158
	159	static int softdog_release(struct inode inode, struct file file)
	160	{
	161	/*
	162	* Shut off the timer.
5f3b2756	163	* Lock it in if it's a module and we set nowayout
1da177e4 LT	164	*/
	165	if (expect_close == 42) {
	166	softdog_stop();
1cc77248	167	module_put(THIS_MODULE);
1da177e4	168	} else {
27c766aa	169	pr_crit("Unexpected close, not stopping watchdog!\n");
1cc77248	170	set_bit(0, &orphan_timer);
1da177e4 LT	171	softdog_keepalive();
1da177e4 LT	172	}
1cc77248	173	clear_bit(0, &driver_open);
1da177e4 LT	174	expect_close = 0;
	175	return 0;
	176	}
	177
f92d3749 AC	178	static ssize_t softdog_write(struct file file, const char __user data,
f92d3749 AC	179	size_t len, loff_t *ppos)
1da177e4 LT	180	{
	181	/*
	182	* Refresh the timer.
	183	*/
f92d3749	184	if (len) {
1da177e4 LT	185	if (!nowayout) {
	186	size_t i;
	187
	188	/* In case it was set long ago */
	189	expect_close = 0;
	190
	191	for (i = 0; i != len; i++) {
	192	char c;
	193
	194	if (get_user(c, data + i))
	195	return -EFAULT;
	196	if (c == 'V')
	197	expect_close = 42;
	198	}
	199	}
	200	softdog_keepalive();
	201	}
	202	return len;
	203	}
	204
f92d3749 AC	205	static long softdog_ioctl(struct file *file, unsigned int cmd,
f92d3749 AC	206	unsigned long arg)
1da177e4 LT	207	{
	208	void __user argp = (void __user )arg;
	209	int __user *p = argp;
	210	int new_margin;
f92d3749	211	static const struct watchdog_info ident = {
1da177e4 LT	212	.options = WDIOF_SETTIMEOUT \|
	213	WDIOF_KEEPALIVEPING \|
	214	WDIOF_MAGICCLOSE,
	215	.firmware_version = 0,
	216	.identity = "Software Watchdog",
	217	};
	218	switch (cmd) {
f92d3749 AC	219	case WDIOC_GETSUPPORT:
	220	return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	221	case WDIOC_GETSTATUS:
	222	case WDIOC_GETBOOTSTATUS:
	223	return put_user(0, p);
	224	case WDIOC_KEEPALIVE:
	225	softdog_keepalive();
	226	return 0;
	227	case WDIOC_SETTIMEOUT:
	228	if (get_user(new_margin, p))
	229	return -EFAULT;
	230	if (softdog_set_heartbeat(new_margin))
	231	return -EINVAL;
	232	softdog_keepalive();
	233	/* Fall */
	234	case WDIOC_GETTIMEOUT:
	235	return put_user(soft_margin, p);
0c06090c WVS	236	default:
0c06090c WVS	237	return -ENOTTY;
1da177e4 LT	238	}
	239	}
	240
	241	/*
	242	* Notifier for system down
	243	*/
	244
	245	static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
	246	void *unused)
	247	{
f92d3749	248	if (code == SYS_DOWN \|\| code == SYS_HALT)
1da177e4 LT	249	/* Turn the WDT off */
1da177e4 LT	250	softdog_stop();
1da177e4 LT	251	return NOTIFY_DONE;
	252	}
	253
	254	/*
	255	* Kernel Interfaces
	256	*/
	257
62322d25	258	static const struct file_operations softdog_fops = {
1da177e4 LT	259	.owner = THIS_MODULE,
	260	.llseek = no_llseek,
	261	.write = softdog_write,
f92d3749	262	.unlocked_ioctl = softdog_ioctl,
1da177e4 LT	263	.open = softdog_open,
	264	.release = softdog_release,
	265	};
	266
	267	static struct miscdevice softdog_miscdev = {
	268	.minor = WATCHDOG_MINOR,
	269	.name = "watchdog",
	270	.fops = &softdog_fops,
	271	};
	272
	273	static struct notifier_block softdog_notifier = {
	274	.notifier_call = softdog_notify_sys,
	275	};
	276
1da177e4 LT	277	static int __init watchdog_init(void)
	278	{
	279	int ret;
	280
f92d3749 AC	281	/* Check that the soft_margin value is within it's range;
f92d3749 AC	282	if not reset to the default */
1da177e4 LT	283	if (softdog_set_heartbeat(soft_margin)) {
1da177e4 LT	284	softdog_set_heartbeat(TIMER_MARGIN);
27c766aa	285	pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
1da177e4 LT	286	TIMER_MARGIN);
	287	}
	288
	289	ret = register_reboot_notifier(&softdog_notifier);
	290	if (ret) {
27c766aa	291	pr_err("cannot register reboot notifier (err=%d)\n", ret);
1da177e4 LT	292	return ret;
	293	}
	294
	295	ret = misc_register(&softdog_miscdev);
	296	if (ret) {
27c766aa JP	297	pr_err("cannot register miscdev on minor=%d (err=%d)\n",
27c766aa JP	298	WATCHDOG_MINOR, ret);
1da177e4 LT	299	unregister_reboot_notifier(&softdog_notifier);
	300	return ret;
	301	}
	302
27c766aa JP	303	pr_info("Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout= %d)\n",
27c766aa JP	304	soft_noboot, soft_margin, soft_panic, nowayout);
1da177e4 LT	305
	306	return 0;
	307	}
	308
	309	static void __exit watchdog_exit(void)
	310	{
	311	misc_deregister(&softdog_miscdev);
	312	unregister_reboot_notifier(&softdog_notifier);
	313	}
	314
	315	module_init(watchdog_init);
	316	module_exit(watchdog_exit);
	317
	318	MODULE_AUTHOR("Alan Cox");
	319	MODULE_DESCRIPTION("Software Watchdog Device Driver");
	320	MODULE_LICENSE("GPL");
	321	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);