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

/*
 *	watchdog_core.c
 *
 *	(c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
 *						All Rights Reserved.
 *
 *	(c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
 *
 *	This source code is part of the generic code that can be used
 *	by all the watchdog timer drivers.
 *
 *	Based on source code of the following authors:
 *	  Matt Domsch <Matt_Domsch@dell.com>,
 *	  Rob Radez <rob@osinvestor.com>,
 *	  Rusty Lynch <rusty@linux.co.intel.com>
 *	  Satyam Sharma <satyam@infradead.org>
 *	  Randy Dunlap <randy.dunlap@oracle.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, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
 *	admit liability nor provide warranty for any of this software.
 *	This material is provided "AS-IS" and at no charge.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>	/* For EXPORT_SYMBOL/module stuff/... */
#include <linux/types.h>	/* For standard types */
#include <linux/errno.h>	/* For the -ENODEV/... values */
#include <linux/kernel.h>	/* For printk/panic/... */
#include <linux/reboot.h>	/* For restart handler */
#include <linux/watchdog.h>	/* For watchdog specific items */
#include <linux/init.h>		/* For __init/__exit/... */
#include <linux/idr.h>		/* For ida_* macros */
#include <linux/err.h>		/* For IS_ERR macros */
#include <linux/of.h>		/* For of_get_timeout_sec */

#include "watchdog_core.h"	/* For watchdog_dev_register/... */

static DEFINE_IDA(watchdog_ida);

/*
 * Deferred Registration infrastructure.
 *
 * Sometimes watchdog drivers needs to be loaded as soon as possible,
 * for example when it's impossible to disable it. To do so,
 * raising the initcall level of the watchdog driver is a solution.
 * But in such case, the miscdev is maybe not ready (subsys_initcall), and
 * watchdog_core need miscdev to register the watchdog as a char device.
 *
 * The deferred registration infrastructure offer a way for the watchdog
 * subsystem to register a watchdog properly, even before miscdev is ready.
 */

static DEFINE_MUTEX(wtd_deferred_reg_mutex);
static LIST_HEAD(wtd_deferred_reg_list);
static bool wtd_deferred_reg_done;

static int watchdog_deferred_registration_add(struct watchdog_device *wdd)
{
	list_add_tail(&wdd->deferred,
		      &wtd_deferred_reg_list);
	return 0;
}

static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
{
	struct list_head *p, *n;
	struct watchdog_device *wdd_tmp;

	list_for_each_safe(p, n, &wtd_deferred_reg_list) {
		wdd_tmp = list_entry(p, struct watchdog_device,
				     deferred);
		if (wdd_tmp == wdd) {
			list_del(&wdd_tmp->deferred);
			break;
		}
	}
}

static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
{
	/*
	 * Check that we have valid min and max timeout values, if
	 * not reset them both to 0 (=not used or unknown)
	 */
	if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {
		pr_info("Invalid min and max timeout values, resetting to 0!\n");
		wdd->min_timeout = 0;
		wdd->max_timeout = 0;
	}
}

/**
 * watchdog_init_timeout() - initialize the timeout field
 * @wdd: watchdog device
 * @timeout_parm: timeout module parameter
 * @dev: Device that stores the timeout-sec property
 *
 * Initialize the timeout field of the watchdog_device struct with either the
 * timeout module parameter (if it is valid value) or the timeout-sec property
 * (only if it is a valid value and the timeout_parm is out of bounds).
 * If none of them are valid then we keep the old value (which should normally
 * be the default timeout value). Note that for the module parameter, '0' means
 * 'use default' while it is an invalid value for the timeout-sec property.
 * It should simply be dropped if you want to use the default value then.
 *
 * A zero is returned on success or -EINVAL if all provided values are out of
 * bounds.
 */
int watchdog_init_timeout(struct watchdog_device *wdd,
				unsigned int timeout_parm, struct device *dev)
{
	const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
			      (const char *)wdd->info->identity;
	unsigned int t = 0;
	int ret = 0;

	watchdog_check_min_max_timeout(wdd);

	/* check the driver supplied value (likely a module parameter) first */
	if (timeout_parm) {
		if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
			wdd->timeout = timeout_parm;
			return 0;
		}
		pr_err("%s: driver supplied timeout (%u) out of range\n",
			dev_str, timeout_parm);
		ret = -EINVAL;
	}

	/* try to get the timeout_sec property */
	if (dev && dev->of_node &&
	    of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) {
		if (t && !watchdog_timeout_invalid(wdd, t)) {
			wdd->timeout = t;
			return 0;
		}
		pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t);
		ret = -EINVAL;
	}

	if (ret < 0 && wdd->timeout)
		pr_warn("%s: falling back to default timeout (%u)\n", dev_str,
			wdd->timeout);

	return ret;
}
EXPORT_SYMBOL_GPL(watchdog_init_timeout);

static int watchdog_restart_notifier(struct notifier_block *nb,
				     unsigned long action, void *data)
{
	struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
						   restart_nb);

	int ret;

	ret = wdd->ops->restart(wdd, action, data);
	if (ret)
		return NOTIFY_BAD;

	return NOTIFY_DONE;
}

/**
 * watchdog_set_restart_priority - Change priority of restart handler
 * @wdd: watchdog device
 * @priority: priority of the restart handler, should follow these guidelines:
 *   0:   use watchdog's restart function as last resort, has limited restart
 *        capabilies
 *   128: default restart handler, use if no other handler is expected to be
 *        available and/or if restart is sufficient to restart the entire system
 *   255: preempt all other handlers
 *
 * If a wdd->ops->restart function is provided when watchdog_register_device is
 * called, it will be registered as a restart handler with the priority given
 * here.
 */
void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
{
	wdd->restart_nb.priority = priority;
}
EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);

static int __watchdog_register_device(struct watchdog_device *wdd)
{
	int ret, id = -1;

	if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
		return -EINVAL;

	/* Mandatory operations need to be supported */
	if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
		return -EINVAL;

	watchdog_check_min_max_timeout(wdd);

	/*
	 * Note: now that all watchdog_device data has been verified, we
	 * will not check this anymore in other functions. If data gets
	 * corrupted in a later stage then we expect a kernel panic!
	 */

	/* Use alias for watchdog id if possible */
	if (wdd->parent) {
		ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
		if (ret >= 0)
			id = ida_simple_get(&watchdog_ida, ret,
					    ret + 1, GFP_KERNEL);
	}

	if (id < 0)
		id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);

	if (id < 0)
		return id;
	wdd->id = id;

	ret = watchdog_dev_register(wdd);
	if (ret) {
		ida_simple_remove(&watchdog_ida, id);
		if (!(id == 0 && ret == -EBUSY))
			return ret;

		/* Retry in case a legacy watchdog module exists */
		id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
		if (id < 0)
			return id;
		wdd->id = id;

		ret = watchdog_dev_register(wdd);
		if (ret) {
			ida_simple_remove(&watchdog_ida, id);
			return ret;
		}
	}

	if (wdd->ops->restart) {
		wdd->restart_nb.notifier_call = watchdog_restart_notifier;

		ret = register_restart_handler(&wdd->restart_nb);
		if (ret)
			pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
				wdd->id, ret);
	}

	return 0;
}

/**
 * watchdog_register_device() - register a watchdog device
 * @wdd: watchdog device
 *
 * Register a watchdog device with the kernel so that the
 * watchdog timer can be accessed from userspace.
 *
 * A zero is returned on success and a negative errno code for
 * failure.
 */

int watchdog_register_device(struct watchdog_device *wdd)
{
	int ret;

	mutex_lock(&wtd_deferred_reg_mutex);
	if (wtd_deferred_reg_done)
		ret = __watchdog_register_device(wdd);
	else
		ret = watchdog_deferred_registration_add(wdd);
	mutex_unlock(&wtd_deferred_reg_mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(watchdog_register_device);

static void __watchdog_unregister_device(struct watchdog_device *wdd)
{
	if (wdd == NULL)
		return;

	if (wdd->ops->restart)
		unregister_restart_handler(&wdd->restart_nb);

	watchdog_dev_unregister(wdd);
	ida_simple_remove(&watchdog_ida, wdd->id);
}

/**
 * watchdog_unregister_device() - unregister a watchdog device
 * @wdd: watchdog device to unregister
 *
 * Unregister a watchdog device that was previously successfully
 * registered with watchdog_register_device().
 */

void watchdog_unregister_device(struct watchdog_device *wdd)
{
	mutex_lock(&wtd_deferred_reg_mutex);
	if (wtd_deferred_reg_done)
		__watchdog_unregister_device(wdd);
	else
		watchdog_deferred_registration_del(wdd);
	mutex_unlock(&wtd_deferred_reg_mutex);
}

EXPORT_SYMBOL_GPL(watchdog_unregister_device);

static void devm_watchdog_unregister_device(struct device *dev, void *res)
{
	watchdog_unregister_device(*(struct watchdog_device **)res);
}

/**
 * devm_watchdog_register_device() - resource managed watchdog_register_device()
 * @dev: device that is registering this watchdog device
 * @wdd: watchdog device
 *
 * Managed watchdog_register_device(). For watchdog device registered by this
 * function,  watchdog_unregister_device() is automatically called on driver
 * detach. See watchdog_register_device() for more information.
 */
int devm_watchdog_register_device(struct device *dev,
				struct watchdog_device *wdd)
{
	struct watchdog_device **rcwdd;
	int ret;

	rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
			     GFP_KERNEL);
	if (!rcwdd)
		return -ENOMEM;

	ret = watchdog_register_device(wdd);
	if (!ret) {
		*rcwdd = wdd;
		devres_add(dev, rcwdd);
	} else {
		devres_free(rcwdd);
	}

	return ret;
}
EXPORT_SYMBOL_GPL(devm_watchdog_register_device);

static int __init watchdog_deferred_registration(void)
{
	mutex_lock(&wtd_deferred_reg_mutex);
	wtd_deferred_reg_done = true;
	while (!list_empty(&wtd_deferred_reg_list)) {
		struct watchdog_device *wdd;

		wdd = list_first_entry(&wtd_deferred_reg_list,
				       struct watchdog_device, deferred);
		list_del(&wdd->deferred);
		__watchdog_register_device(wdd);
	}
	mutex_unlock(&wtd_deferred_reg_mutex);
	return 0;
}

static int __init watchdog_init(void)
{
	int err;

	err = watchdog_dev_init();
	if (err < 0)
		return err;

	watchdog_deferred_registration();
	return 0;
}

static void __exit watchdog_exit(void)
{
	watchdog_dev_exit();
	ida_destroy(&watchdog_ida);
}

subsys_initcall_sync(watchdog_init);
module_exit(watchdog_exit);

MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
MODULE_DESCRIPTION("WatchDog Timer Driver Core");
MODULE_LICENSE("GPL");
Commit	Line	Data
43316044 WVS	1	/*
	2	* watchdog_core.c
	3	*
	4	* (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
	5	* All Rights Reserved.
	6	*
	7	* (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
	8	*
	9	* This source code is part of the generic code that can be used
	10	* by all the watchdog timer drivers.
	11	*
	12	* Based on source code of the following authors:
	13	* Matt Domsch <Matt_Domsch@dell.com>,
	14	* Rob Radez <rob@osinvestor.com>,
	15	* Rusty Lynch <rusty@linux.co.intel.com>
	16	* Satyam Sharma <satyam@infradead.org>
	17	* Randy Dunlap <randy.dunlap@oracle.com>
	18	*
	19	* This program is free software; you can redistribute it and/or
	20	* modify it under the terms of the GNU General Public License
	21	* as published by the Free Software Foundation; either version
	22	* 2 of the License, or (at your option) any later version.
	23	*
	24	* Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
	25	* admit liability nor provide warranty for any of this software.
	26	* This material is provided "AS-IS" and at no charge.
	27	*/
	28
	29	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	30
	31	#include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */
	32	#include <linux/types.h> /* For standard types */
	33	#include <linux/errno.h> /* For the -ENODEV/... values */
	34	#include <linux/kernel.h> /* For printk/panic/... */
2165bf52	35	#include <linux/reboot.h> /* For restart handler */
43316044 WVS	36	#include <linux/watchdog.h> /* For watchdog specific items */
43316044 WVS	37	#include <linux/init.h> /* For __init/__exit/... */
45f5fed3	38	#include <linux/idr.h> /* For ida_* macros */
d6b469d9	39	#include <linux/err.h> /* For IS_ERR macros */
3048253e	40	#include <linux/of.h> /* For of_get_timeout_sec */
43316044	41
6cfb5aa8	42	#include "watchdog_core.h" /* For watchdog_dev_register/... */
43316044	43
45f5fed3 AC	44	static DEFINE_IDA(watchdog_ida);
45f5fed3 AC	45
ef90174f JBT	46	/*
	47	* Deferred Registration infrastructure.
	48	*
	49	* Sometimes watchdog drivers needs to be loaded as soon as possible,
	50	* for example when it's impossible to disable it. To do so,
	51	* raising the initcall level of the watchdog driver is a solution.
	52	* But in such case, the miscdev is maybe not ready (subsys_initcall), and
	53	* watchdog_core need miscdev to register the watchdog as a char device.
	54	*
	55	* The deferred registration infrastructure offer a way for the watchdog
	56	* subsystem to register a watchdog properly, even before miscdev is ready.
	57	*/
	58
	59	static DEFINE_MUTEX(wtd_deferred_reg_mutex);
	60	static LIST_HEAD(wtd_deferred_reg_list);
	61	static bool wtd_deferred_reg_done;
	62
	63	static int watchdog_deferred_registration_add(struct watchdog_device *wdd)
	64	{
	65	list_add_tail(&wdd->deferred,
	66	&wtd_deferred_reg_list);
	67	return 0;
	68	}
	69
	70	static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
	71	{
	72	struct list_head p, n;
	73	struct watchdog_device *wdd_tmp;
	74
	75	list_for_each_safe(p, n, &wtd_deferred_reg_list) {
	76	wdd_tmp = list_entry(p, struct watchdog_device,
	77	deferred);
	78	if (wdd_tmp == wdd) {
	79	list_del(&wdd_tmp->deferred);
	80	break;
	81	}
	82	}
	83	}
	84
3048253e FP	85	static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
	86	{
	87	/*
	88	* Check that we have valid min and max timeout values, if
	89	* not reset them both to 0 (=not used or unknown)
	90	*/
1894cad9	91	if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {
3048253e FP	92	pr_info("Invalid min and max timeout values, resetting to 0!\n");
	93	wdd->min_timeout = 0;
	94	wdd->max_timeout = 0;
	95	}
	96	}
	97
	98	/**
	99	* watchdog_init_timeout() - initialize the timeout field
8bc86475	100	* @wdd: watchdog device
3048253e FP	101	* @timeout_parm: timeout module parameter
	102	* @dev: Device that stores the timeout-sec property
	103	*
	104	* Initialize the timeout field of the watchdog_device struct with either the
	105	* timeout module parameter (if it is valid value) or the timeout-sec property
	106	* (only if it is a valid value and the timeout_parm is out of bounds).
	107	* If none of them are valid then we keep the old value (which should normally
34ef4087 WS	108	* be the default timeout value). Note that for the module parameter, '0' means
	109	* 'use default' while it is an invalid value for the timeout-sec property.
	110	* It should simply be dropped if you want to use the default value then.
3048253e	111	*
34ef4087 WS	112	* A zero is returned on success or -EINVAL if all provided values are out of
34ef4087 WS	113	* bounds.
3048253e FP	114	*/
	115	int watchdog_init_timeout(struct watchdog_device *wdd,
	116	unsigned int timeout_parm, struct device *dev)
	117	{
e907972b WS	118	const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
e907972b WS	119	(const char *)wdd->info->identity;
3048253e FP	120	unsigned int t = 0;
	121	int ret = 0;
	122
	123	watchdog_check_min_max_timeout(wdd);
	124
34ef4087 WS	125	/* check the driver supplied value (likely a module parameter) first */
	126	if (timeout_parm) {
	127	if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
	128	wdd->timeout = timeout_parm;
	129	return 0;
	130	}
e907972b WS	131	pr_err("%s: driver supplied timeout (%u) out of range\n",
e907972b WS	132	dev_str, timeout_parm);
3048253e	133	ret = -EINVAL;
34ef4087	134	}
3048253e FP	135
3048253e FP	136	/* try to get the timeout_sec property */
34ef4087 WS	137	if (dev && dev->of_node &&
	138	of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) {
	139	if (t && !watchdog_timeout_invalid(wdd, t)) {
	140	wdd->timeout = t;
	141	return 0;
	142	}
e907972b	143	pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t);
3048253e	144	ret = -EINVAL;
34ef4087	145	}
3048253e	146
e907972b WS	147	if (ret < 0 && wdd->timeout)
	148	pr_warn("%s: falling back to default timeout (%u)\n", dev_str,
	149	wdd->timeout);
	150
3048253e FP	151	return ret;
	152	}
	153	EXPORT_SYMBOL_GPL(watchdog_init_timeout);
	154
2165bf52 DR	155	static int watchdog_restart_notifier(struct notifier_block *nb,
	156	unsigned long action, void *data)
	157	{
	158	struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
	159	restart_nb);
	160
	161	int ret;
	162
4d8b229d	163	ret = wdd->ops->restart(wdd, action, data);
2165bf52 DR	164	if (ret)
	165	return NOTIFY_BAD;
	166
	167	return NOTIFY_DONE;
	168	}
	169
	170	/**
	171	* watchdog_set_restart_priority - Change priority of restart handler
	172	* @wdd: watchdog device
	173	* @priority: priority of the restart handler, should follow these guidelines:
	174	* 0: use watchdog's restart function as last resort, has limited restart
	175	* capabilies
	176	* 128: default restart handler, use if no other handler is expected to be
	177	* available and/or if restart is sufficient to restart the entire system
	178	* 255: preempt all other handlers
	179	*
	180	* If a wdd->ops->restart function is provided when watchdog_register_device is
	181	* called, it will be registered as a restart handler with the priority given
	182	* here.
	183	*/
	184	void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
	185	{
	186	wdd->restart_nb.priority = priority;
	187	}
	188	EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
	189
ef90174f	190	static int __watchdog_register_device(struct watchdog_device *wdd)
43316044	191	{
32ecc639	192	int ret, id = -1;
43316044 WVS	193
	194	if (wdd == NULL \|\| wdd->info == NULL \|\| wdd->ops == NULL)
	195	return -EINVAL;
	196
	197	/* Mandatory operations need to be supported */
d0684c8a	198	if (!wdd->ops->start \|\| (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
43316044 WVS	199	return -EINVAL;
43316044 WVS	200
3048253e	201	watchdog_check_min_max_timeout(wdd);
3f43f68e	202
43316044 WVS	203	/*
	204	* Note: now that all watchdog_device data has been verified, we
	205	* will not check this anymore in other functions. If data gets
	206	* corrupted in a later stage then we expect a kernel panic!
	207	*/
	208
9dd4e173 JC	209	/* Use alias for watchdog id if possible */
	210	if (wdd->parent) {
	211	ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
	212	if (ret >= 0)
	213	id = ida_simple_get(&watchdog_ida, ret,
	214	ret + 1, GFP_KERNEL);
	215	}
	216
	217	if (id < 0)
	218	id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
	219
45f5fed3 AC	220	if (id < 0)
	221	return id;
	222	wdd->id = id;
	223
43316044 WVS	224	ret = watchdog_dev_register(wdd);
43316044 WVS	225	if (ret) {
45f5fed3 AC	226	ida_simple_remove(&watchdog_ida, id);
	227	if (!(id == 0 && ret == -EBUSY))
	228	return ret;
	229
	230	/* Retry in case a legacy watchdog module exists */
	231	id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
	232	if (id < 0)
	233	return id;
	234	wdd->id = id;
	235
	236	ret = watchdog_dev_register(wdd);
	237	if (ret) {
	238	ida_simple_remove(&watchdog_ida, id);
	239	return ret;
	240	}
43316044 WVS	241	}
43316044 WVS	242
2165bf52 DR	243	if (wdd->ops->restart) {
	244	wdd->restart_nb.notifier_call = watchdog_restart_notifier;
	245
	246	ret = register_restart_handler(&wdd->restart_nb);
	247	if (ret)
c01e0159	248	pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
0254e953	249	wdd->id, ret);
2165bf52 DR	250	}
2165bf52 DR	251
43316044 WVS	252	return 0;
43316044 WVS	253	}
43316044 WVS	254
43316044 WVS	255	/**
ef90174f JBT	256	* watchdog_register_device() - register a watchdog device
ef90174f JBT	257	* @wdd: watchdog device
43316044	258	*
ef90174f JBT	259	* Register a watchdog device with the kernel so that the
	260	* watchdog timer can be accessed from userspace.
	261	*
	262	* A zero is returned on success and a negative errno code for
	263	* failure.
43316044	264	*/
ef90174f JBT	265
	266	int watchdog_register_device(struct watchdog_device *wdd)
	267	{
	268	int ret;
	269
	270	mutex_lock(&wtd_deferred_reg_mutex);
	271	if (wtd_deferred_reg_done)
	272	ret = __watchdog_register_device(wdd);
	273	else
	274	ret = watchdog_deferred_registration_add(wdd);
	275	mutex_unlock(&wtd_deferred_reg_mutex);
	276	return ret;
	277	}
	278	EXPORT_SYMBOL_GPL(watchdog_register_device);
	279
	280	static void __watchdog_unregister_device(struct watchdog_device *wdd)
43316044	281	{
43316044 WVS	282	if (wdd == NULL)
	283	return;
	284
2165bf52 DR	285	if (wdd->ops->restart)
	286	unregister_restart_handler(&wdd->restart_nb);
	287
32ecc639	288	watchdog_dev_unregister(wdd);
45f5fed3	289	ida_simple_remove(&watchdog_ida, wdd->id);
43316044	290	}
ef90174f JBT	291
	292	/**
	293	* watchdog_unregister_device() - unregister a watchdog device
	294	* @wdd: watchdog device to unregister
	295	*
	296	* Unregister a watchdog device that was previously successfully
	297	* registered with watchdog_register_device().
	298	*/
	299
	300	void watchdog_unregister_device(struct watchdog_device *wdd)
	301	{
	302	mutex_lock(&wtd_deferred_reg_mutex);
	303	if (wtd_deferred_reg_done)
	304	__watchdog_unregister_device(wdd);
	305	else
	306	watchdog_deferred_registration_del(wdd);
	307	mutex_unlock(&wtd_deferred_reg_mutex);
	308	}
	309
43316044 WVS	310	EXPORT_SYMBOL_GPL(watchdog_unregister_device);
43316044 WVS	311
83fbae5a NA	312	static void devm_watchdog_unregister_device(struct device dev, void res)
	313	{
	314	watchdog_unregister_device((struct watchdog_device *)res);
	315	}
	316
	317	/**
	318	* devm_watchdog_register_device() - resource managed watchdog_register_device()
	319	* @dev: device that is registering this watchdog device
	320	* @wdd: watchdog device
	321	*
	322	* Managed watchdog_register_device(). For watchdog device registered by this
	323	* function, watchdog_unregister_device() is automatically called on driver
	324	* detach. See watchdog_register_device() for more information.
	325	*/
	326	int devm_watchdog_register_device(struct device *dev,
	327	struct watchdog_device *wdd)
	328	{
	329	struct watchdog_device **rcwdd;
	330	int ret;
	331
2e91838b	332	rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
83fbae5a NA	333	GFP_KERNEL);
	334	if (!rcwdd)
	335	return -ENOMEM;
	336
	337	ret = watchdog_register_device(wdd);
	338	if (!ret) {
	339	*rcwdd = wdd;
	340	devres_add(dev, rcwdd);
	341	} else {
	342	devres_free(rcwdd);
	343	}
	344
	345	return ret;
	346	}
	347	EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
	348
ef90174f JBT	349	static int __init watchdog_deferred_registration(void)
	350	{
	351	mutex_lock(&wtd_deferred_reg_mutex);
	352	wtd_deferred_reg_done = true;
	353	while (!list_empty(&wtd_deferred_reg_list)) {
	354	struct watchdog_device *wdd;
	355
	356	wdd = list_first_entry(&wtd_deferred_reg_list,
	357	struct watchdog_device, deferred);
	358	list_del(&wdd->deferred);
	359	__watchdog_register_device(wdd);
	360	}
	361	mutex_unlock(&wtd_deferred_reg_mutex);
	362	return 0;
	363	}
	364
45f5fed3 AC	365	static int __init watchdog_init(void)
45f5fed3 AC	366	{
32ecc639 GR	367	int err;
	368
	369	err = watchdog_dev_init();
	370	if (err < 0)
	371	return err;
d6b469d9	372
ef90174f	373	watchdog_deferred_registration();
d6b469d9	374	return 0;
45f5fed3 AC	375	}
	376
	377	static void __exit watchdog_exit(void)
	378	{
	379	watchdog_dev_exit();
	380	ida_destroy(&watchdog_ida);
	381	}
	382
ef90174f	383	subsys_initcall_sync(watchdog_init);
45f5fed3 AC	384	module_exit(watchdog_exit);
45f5fed3 AC	385
43316044 WVS	386	MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
	387	MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
	388	MODULE_DESCRIPTION("WatchDog Timer Driver Core");
	389	MODULE_LICENSE("GPL");