[deliverable/linux.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/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);
static struct class *watchdog_class;

/*
 * 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->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
 * @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.
 *
 * A zero is returned on success and -EINVAL for failure.
 */
int watchdog_init_timeout(struct watchdog_device *wdd,
				unsigned int timeout_parm, struct device *dev)
{
	unsigned int t = 0;
	int ret = 0;

	watchdog_check_min_max_timeout(wdd);

	/* try to get the timeout module parameter first */
	if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
		wdd->timeout = timeout_parm;
		return ret;
	}
	if (timeout_parm)
		ret = -EINVAL;

	/* try to get the timeout_sec property */
	if (dev == NULL || dev->of_node == NULL)
		return ret;
	of_property_read_u32(dev->of_node, "timeout-sec", &t);
	if (!watchdog_timeout_invalid(wdd, t) && t)
		wdd->timeout = t;
	else
		ret = -EINVAL;

	return ret;
}
EXPORT_SYMBOL_GPL(watchdog_init_timeout);

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

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

	/* Mandatory operations need to be supported */
	if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
		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!
	 */

	mutex_init(&wdd->lock);

	/* 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;
		}
	}

	devno = wdd->cdev.dev;
	wdd->dev = device_create(watchdog_class, wdd->parent, devno,
					NULL, "watchdog%d", wdd->id);
	if (IS_ERR(wdd->dev)) {
		watchdog_dev_unregister(wdd);
		ida_simple_remove(&watchdog_ida, id);
		ret = PTR_ERR(wdd->dev);
		return 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)
{
	int ret;
	int devno;

	if (wdd == NULL)
		return;

	devno = wdd->cdev.dev;
	ret = watchdog_dev_unregister(wdd);
	if (ret)
		pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
	device_destroy(watchdog_class, devno);
	ida_simple_remove(&watchdog_ida, wdd->id);
	wdd->dev = NULL;
}

/**
 * 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 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;

	watchdog_class = class_create(THIS_MODULE, "watchdog");
	if (IS_ERR(watchdog_class)) {
		pr_err("couldn't create class\n");
		return PTR_ERR(watchdog_class);
	}

	err = watchdog_dev_init();
	if (err < 0) {
		class_destroy(watchdog_class);
		return err;
	}

	watchdog_deferred_registration();
	return 0;
}

static void __exit watchdog_exit(void)
{
	watchdog_dev_exit();
	class_destroy(watchdog_class);
	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/... */
	35	#include <linux/watchdog.h> /* For watchdog specific items */
	36	#include <linux/init.h> /* For __init/__exit/... */
45f5fed3	37	#include <linux/idr.h> /* For ida_* macros */
d6b469d9	38	#include <linux/err.h> /* For IS_ERR macros */
3048253e	39	#include <linux/of.h> /* For of_get_timeout_sec */
43316044	40
6cfb5aa8	41	#include "watchdog_core.h" /* For watchdog_dev_register/... */
43316044	42
45f5fed3	43	static DEFINE_IDA(watchdog_ida);
d6b469d9	44	static struct class *watchdog_class;
45f5fed3	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	*/
	91	if (wdd->min_timeout > wdd->max_timeout) {
	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
	100	* @timeout_parm: timeout module parameter
	101	* @dev: Device that stores the timeout-sec property
	102	*
	103	* Initialize the timeout field of the watchdog_device struct with either the
	104	* timeout module parameter (if it is valid value) or the timeout-sec property
	105	* (only if it is a valid value and the timeout_parm is out of bounds).
	106	* If none of them are valid then we keep the old value (which should normally
	107	* be the default timeout value.
	108	*
	109	* A zero is returned on success and -EINVAL for failure.
	110	*/
	111	int watchdog_init_timeout(struct watchdog_device *wdd,
	112	unsigned int timeout_parm, struct device *dev)
	113	{
	114	unsigned int t = 0;
	115	int ret = 0;
	116
	117	watchdog_check_min_max_timeout(wdd);
	118
6ffcff93	119	/* try to get the timeout module parameter first */
2c34d599	120	if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
3048253e FP	121	wdd->timeout = timeout_parm;
	122	return ret;
	123	}
	124	if (timeout_parm)
	125	ret = -EINVAL;
	126
	127	/* try to get the timeout_sec property */
	128	if (dev == NULL \|\| dev->of_node == NULL)
	129	return ret;
	130	of_property_read_u32(dev->of_node, "timeout-sec", &t);
2c34d599	131	if (!watchdog_timeout_invalid(wdd, t) && t)
3048253e FP	132	wdd->timeout = t;
	133	else
	134	ret = -EINVAL;
	135
	136	return ret;
	137	}
	138	EXPORT_SYMBOL_GPL(watchdog_init_timeout);
	139
ef90174f	140	static int __watchdog_register_device(struct watchdog_device *wdd)
43316044	141	{
9dd4e173	142	int ret, id = -1, devno;
43316044 WVS	143
	144	if (wdd == NULL \|\| wdd->info == NULL \|\| wdd->ops == NULL)
	145	return -EINVAL;
	146
	147	/* Mandatory operations need to be supported */
	148	if (wdd->ops->start == NULL \|\| wdd->ops->stop == NULL)
	149	return -EINVAL;
	150
3048253e	151	watchdog_check_min_max_timeout(wdd);
3f43f68e	152
43316044 WVS	153	/*
	154	* Note: now that all watchdog_device data has been verified, we
	155	* will not check this anymore in other functions. If data gets
	156	* corrupted in a later stage then we expect a kernel panic!
	157	*/
	158
f4e9c82f	159	mutex_init(&wdd->lock);
9dd4e173 JC	160
	161	/* Use alias for watchdog id if possible */
	162	if (wdd->parent) {
	163	ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
	164	if (ret >= 0)
	165	id = ida_simple_get(&watchdog_ida, ret,
	166	ret + 1, GFP_KERNEL);
	167	}
	168
	169	if (id < 0)
	170	id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
	171
45f5fed3 AC	172	if (id < 0)
	173	return id;
	174	wdd->id = id;
	175
43316044 WVS	176	ret = watchdog_dev_register(wdd);
43316044 WVS	177	if (ret) {
45f5fed3 AC	178	ida_simple_remove(&watchdog_ida, id);
	179	if (!(id == 0 && ret == -EBUSY))
	180	return ret;
	181
	182	/* Retry in case a legacy watchdog module exists */
	183	id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
	184	if (id < 0)
	185	return id;
	186	wdd->id = id;
	187
	188	ret = watchdog_dev_register(wdd);
	189	if (ret) {
	190	ida_simple_remove(&watchdog_ida, id);
	191	return ret;
	192	}
43316044 WVS	193	}
43316044 WVS	194
d6b469d9 AC	195	devno = wdd->cdev.dev;
	196	wdd->dev = device_create(watchdog_class, wdd->parent, devno,
	197	NULL, "watchdog%d", wdd->id);
	198	if (IS_ERR(wdd->dev)) {
	199	watchdog_dev_unregister(wdd);
	200	ida_simple_remove(&watchdog_ida, id);
	201	ret = PTR_ERR(wdd->dev);
	202	return ret;
	203	}
	204
43316044 WVS	205	return 0;
43316044 WVS	206	}
43316044 WVS	207
43316044 WVS	208	/**
ef90174f JBT	209	* watchdog_register_device() - register a watchdog device
ef90174f JBT	210	* @wdd: watchdog device
43316044	211	*
ef90174f JBT	212	* Register a watchdog device with the kernel so that the
	213	* watchdog timer can be accessed from userspace.
	214	*
	215	* A zero is returned on success and a negative errno code for
	216	* failure.
43316044	217	*/
ef90174f JBT	218
	219	int watchdog_register_device(struct watchdog_device *wdd)
	220	{
	221	int ret;
	222
	223	mutex_lock(&wtd_deferred_reg_mutex);
	224	if (wtd_deferred_reg_done)
	225	ret = __watchdog_register_device(wdd);
	226	else
	227	ret = watchdog_deferred_registration_add(wdd);
	228	mutex_unlock(&wtd_deferred_reg_mutex);
	229	return ret;
	230	}
	231	EXPORT_SYMBOL_GPL(watchdog_register_device);
	232
	233	static void __watchdog_unregister_device(struct watchdog_device *wdd)
43316044 WVS	234	{
43316044 WVS	235	int ret;
b232a70a	236	int devno;
43316044 WVS	237
	238	if (wdd == NULL)
	239	return;
	240
b232a70a	241	devno = wdd->cdev.dev;
43316044 WVS	242	ret = watchdog_dev_unregister(wdd);
43316044 WVS	243	if (ret)
27c766aa	244	pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
d6b469d9	245	device_destroy(watchdog_class, devno);
45f5fed3	246	ida_simple_remove(&watchdog_ida, wdd->id);
d6b469d9	247	wdd->dev = NULL;
43316044	248	}
ef90174f JBT	249
	250	/**
	251	* watchdog_unregister_device() - unregister a watchdog device
	252	* @wdd: watchdog device to unregister
	253	*
	254	* Unregister a watchdog device that was previously successfully
	255	* registered with watchdog_register_device().
	256	*/
	257
	258	void watchdog_unregister_device(struct watchdog_device *wdd)
	259	{
	260	mutex_lock(&wtd_deferred_reg_mutex);
	261	if (wtd_deferred_reg_done)
	262	__watchdog_unregister_device(wdd);
	263	else
	264	watchdog_deferred_registration_del(wdd);
	265	mutex_unlock(&wtd_deferred_reg_mutex);
	266	}
	267
43316044 WVS	268	EXPORT_SYMBOL_GPL(watchdog_unregister_device);
43316044 WVS	269
ef90174f JBT	270	static int __init watchdog_deferred_registration(void)
	271	{
	272	mutex_lock(&wtd_deferred_reg_mutex);
	273	wtd_deferred_reg_done = true;
	274	while (!list_empty(&wtd_deferred_reg_list)) {
	275	struct watchdog_device *wdd;
	276
	277	wdd = list_first_entry(&wtd_deferred_reg_list,
	278	struct watchdog_device, deferred);
	279	list_del(&wdd->deferred);
	280	__watchdog_register_device(wdd);
	281	}
	282	mutex_unlock(&wtd_deferred_reg_mutex);
	283	return 0;
	284	}
	285
45f5fed3 AC	286	static int __init watchdog_init(void)
45f5fed3 AC	287	{
d6b469d9 AC	288	int err;
	289
	290	watchdog_class = class_create(THIS_MODULE, "watchdog");
	291	if (IS_ERR(watchdog_class)) {
	292	pr_err("couldn't create class\n");
	293	return PTR_ERR(watchdog_class);
	294	}
	295
	296	err = watchdog_dev_init();
	297	if (err < 0) {
	298	class_destroy(watchdog_class);
	299	return err;
	300	}
	301
ef90174f	302	watchdog_deferred_registration();
d6b469d9	303	return 0;
45f5fed3 AC	304	}
	305
	306	static void __exit watchdog_exit(void)
	307	{
	308	watchdog_dev_exit();
d6b469d9	309	class_destroy(watchdog_class);
45f5fed3 AC	310	ida_destroy(&watchdog_ida);
	311	}
	312
ef90174f	313	subsys_initcall_sync(watchdog_init);
45f5fed3 AC	314	module_exit(watchdog_exit);
45f5fed3 AC	315
43316044 WVS	316	MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
	317	MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
	318	MODULE_DESCRIPTION("WatchDog Timer Driver Core");
	319	MODULE_LICENSE("GPL");