[deliverable/linux.git] / drivers / char / watchdog / softdog.c

/*
 *	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/config.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 <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 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);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* SoftDog 0.07: A Software Watchdog Device
	3	*
	4	* (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
	5	* http://www.redhat.com
	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>
	36	* Added Matt Domsch's nowayout module option.
	37	*/
	38
	39	#include <linux/module.h>
	40	#include <linux/moduleparam.h>
	41	#include <linux/config.h>
	42	#include <linux/types.h>
	43	#include <linux/timer.h>
	44	#include <linux/miscdevice.h>
	45	#include <linux/watchdog.h>
	46	#include <linux/fs.h>
	47	#include <linux/notifier.h>
	48	#include <linux/reboot.h>
	49	#include <linux/init.h>
	50	#include <asm/uaccess.h>
	51
	52	#define PFX "SoftDog: "
	53
	54	#define TIMER_MARGIN 60 /* Default is 60 seconds */
	55	static int soft_margin = TIMER_MARGIN; /* in seconds */
	56	module_param(soft_margin, int, 0);
	57	MODULE_PARM_DESC(soft_margin, "Watchdog soft_margin in seconds. (0<soft_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
	58
4bfdf378	59	static int nowayout = WATCHDOG_NOWAYOUT;
1da177e4 LT	60	module_param(nowayout, int, 0);
	61	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
	62
	63	#ifdef ONLY_TESTING
	64	static int soft_noboot = 1;
	65	#else
	66	static int soft_noboot = 0;
	67	#endif /* ONLY_TESTING */
	68
	69	module_param(soft_noboot, int, 0);
	70	MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
	71
	72	/*
	73	* Our timer
	74	*/
	75
	76	static void watchdog_fire(unsigned long);
	77
	78	static struct timer_list watchdog_ticktock =
	79	TIMER_INITIALIZER(watchdog_fire, 0, 0);
1cc77248	80	static unsigned long driver_open, orphan_timer;
1da177e4 LT	81	static char expect_close;
	82
	83
	84	/*
	85	* If the timer expires..
	86	*/
	87
	88	static void watchdog_fire(unsigned long data)
	89	{
1cc77248 CE	90	if (test_and_clear_bit(0, &orphan_timer))
	91	module_put(THIS_MODULE);
	92
1da177e4 LT	93	if (soft_noboot)
	94	printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
	95	else
	96	{
	97	printk(KERN_CRIT PFX "Initiating system reboot.\n");
479d0f41	98	emergency_restart();
1da177e4 LT	99	printk(KERN_CRIT PFX "Reboot didn't ?????\n");
	100	}
	101	}
	102
	103	/*
	104	* Softdog operations
	105	*/
	106
	107	static int softdog_keepalive(void)
	108	{
	109	mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
	110	return 0;
	111	}
	112
	113	static int softdog_stop(void)
	114	{
	115	del_timer(&watchdog_ticktock);
	116	return 0;
	117	}
	118
	119	static int softdog_set_heartbeat(int t)
	120	{
	121	if ((t < 0x0001) \|\| (t > 0xFFFF))
	122	return -EINVAL;
	123
	124	soft_margin = t;
	125	return 0;
	126	}
	127
	128	/*
	129	* /dev/watchdog handling
	130	*/
	131
	132	static int softdog_open(struct inode inode, struct file file)
	133	{
1cc77248	134	if (test_and_set_bit(0, &driver_open))
1da177e4	135	return -EBUSY;
1cc77248	136	if (!test_and_clear_bit(0, &orphan_timer))
1da177e4 LT	137	__module_get(THIS_MODULE);
	138	/*
	139	* Activate timer
	140	*/
	141	softdog_keepalive();
	142	return nonseekable_open(inode, file);
	143	}
	144
	145	static int softdog_release(struct inode inode, struct file file)
	146	{
	147	/*
	148	* Shut off the timer.
	149	* Lock it in if it's a module and we set nowayout
	150	*/
	151	if (expect_close == 42) {
	152	softdog_stop();
1cc77248	153	module_put(THIS_MODULE);
1da177e4 LT	154	} else {
1da177e4 LT	155	printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
1cc77248	156	set_bit(0, &orphan_timer);
1da177e4 LT	157	softdog_keepalive();
1da177e4 LT	158	}
1cc77248	159	clear_bit(0, &driver_open);
1da177e4 LT	160	expect_close = 0;
	161	return 0;
	162	}
	163
	164	static ssize_t softdog_write(struct file file, const char __user data, size_t len, loff_t *ppos)
	165	{
	166	/*
	167	* Refresh the timer.
	168	*/
	169	if(len) {
	170	if (!nowayout) {
	171	size_t i;
	172
	173	/* In case it was set long ago */
	174	expect_close = 0;
	175
	176	for (i = 0; i != len; i++) {
	177	char c;
	178
	179	if (get_user(c, data + i))
	180	return -EFAULT;
	181	if (c == 'V')
	182	expect_close = 42;
	183	}
	184	}
	185	softdog_keepalive();
	186	}
	187	return len;
	188	}
	189
	190	static int softdog_ioctl(struct inode inode, struct file file,
	191	unsigned int cmd, unsigned long arg)
	192	{
	193	void __user argp = (void __user )arg;
	194	int __user *p = argp;
	195	int new_margin;
	196	static struct watchdog_info ident = {
	197	.options = WDIOF_SETTIMEOUT \|
	198	WDIOF_KEEPALIVEPING \|
	199	WDIOF_MAGICCLOSE,
	200	.firmware_version = 0,
	201	.identity = "Software Watchdog",
	202	};
	203	switch (cmd) {
	204	default:
	205	return -ENOIOCTLCMD;
	206	case WDIOC_GETSUPPORT:
	207	return copy_to_user(argp, &ident,
	208	sizeof(ident)) ? -EFAULT : 0;
	209	case WDIOC_GETSTATUS:
	210	case WDIOC_GETBOOTSTATUS:
	211	return put_user(0, p);
	212	case WDIOC_KEEPALIVE:
	213	softdog_keepalive();
	214	return 0;
	215	case WDIOC_SETTIMEOUT:
	216	if (get_user(new_margin, p))
	217	return -EFAULT;
	218	if (softdog_set_heartbeat(new_margin))
	219	return -EINVAL;
	220	softdog_keepalive();
	221	/* Fall */
	222	case WDIOC_GETTIMEOUT:
	223	return put_user(soft_margin, p);
224	}
225	}
226
227	/*
228	* Notifier for system down
229	*/
230
231	static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
232	void *unused)
233	{
234	if(code==SYS_DOWN \|\| code==SYS_HALT) {
235	/* Turn the WDT off */
236	softdog_stop();
237	}
238	return NOTIFY_DONE;
239	}
240
241	/*
242	* Kernel Interfaces
243	*/
244
245	static struct file_operations softdog_fops = {
246	.owner = THIS_MODULE,
247	.llseek = no_llseek,
248	.write = softdog_write,
249	.ioctl = softdog_ioctl,
250	.open = softdog_open,
251	.release = softdog_release,
252	};
253
254	static struct miscdevice softdog_miscdev = {
255	.minor = WATCHDOG_MINOR,
256	.name = "watchdog",
257	.fops = &softdog_fops,
258	};
259
260	static struct notifier_block softdog_notifier = {
261	.notifier_call = softdog_notify_sys,
262	};
263
264	static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
265
266	static int __init watchdog_init(void)
267	{
268	int ret;
269
270	/* Check that the soft_margin value is within it's range ; if not reset to the default */
271	if (softdog_set_heartbeat(soft_margin)) {
272	softdog_set_heartbeat(TIMER_MARGIN);
273	printk(KERN_INFO PFX "soft_margin value must be 0<soft_margin<65536, using %d\n",
274	TIMER_MARGIN);
275	}
276
277	ret = register_reboot_notifier(&softdog_notifier);
278	if (ret) {
279	printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
280	ret);
281	return ret;
282	}
283
284	ret = misc_register(&softdog_miscdev);
285	if (ret) {
286	printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
287	WATCHDOG_MINOR, ret);
288	unregister_reboot_notifier(&softdog_notifier);
289	return ret;
290	}
291
292	printk(banner, soft_noboot, soft_margin, nowayout);
293
294	return 0;
295	}
296
297	static void __exit watchdog_exit(void)
298	{
299	misc_deregister(&softdog_miscdev);
300	unregister_reboot_notifier(&softdog_notifier);
301	}
302
303	module_init(watchdog_init);
304	module_exit(watchdog_exit);
305
306	MODULE_AUTHOR("Alan Cox");
307	MODULE_DESCRIPTION("Software Watchdog Device Driver");
308	MODULE_LICENSE("GPL");
309	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);