[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/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;

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);

/**
 * 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, id, 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);
	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;
}
EXPORT_SYMBOL_GPL(watchdog_register_device);

/**
 * 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)
{
	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;
}
EXPORT_SYMBOL_GPL(watchdog_unregister_device);

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;
	}

	return 0;
}

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

subsys_initcall(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
3048253e FP	46	static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
	47	{
	48	/*
	49	* Check that we have valid min and max timeout values, if
	50	* not reset them both to 0 (=not used or unknown)
	51	*/
	52	if (wdd->min_timeout > wdd->max_timeout) {
	53	pr_info("Invalid min and max timeout values, resetting to 0!\n");
	54	wdd->min_timeout = 0;
	55	wdd->max_timeout = 0;
	56	}
	57	}
	58
	59	/**
	60	* watchdog_init_timeout() - initialize the timeout field
	61	* @timeout_parm: timeout module parameter
	62	* @dev: Device that stores the timeout-sec property
	63	*
	64	* Initialize the timeout field of the watchdog_device struct with either the
	65	* timeout module parameter (if it is valid value) or the timeout-sec property
	66	* (only if it is a valid value and the timeout_parm is out of bounds).
	67	* If none of them are valid then we keep the old value (which should normally
	68	* be the default timeout value.
	69	*
	70	* A zero is returned on success and -EINVAL for failure.
	71	*/
	72	int watchdog_init_timeout(struct watchdog_device *wdd,
	73	unsigned int timeout_parm, struct device *dev)
	74	{
	75	unsigned int t = 0;
	76	int ret = 0;
	77
	78	watchdog_check_min_max_timeout(wdd);
	79
6ffcff93	80	/* try to get the timeout module parameter first */
2c34d599	81	if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
3048253e FP	82	wdd->timeout = timeout_parm;
	83	return ret;
	84	}
	85	if (timeout_parm)
	86	ret = -EINVAL;
	87
	88	/* try to get the timeout_sec property */
	89	if (dev == NULL \|\| dev->of_node == NULL)
	90	return ret;
	91	of_property_read_u32(dev->of_node, "timeout-sec", &t);
2c34d599	92	if (!watchdog_timeout_invalid(wdd, t) && t)
3048253e FP	93	wdd->timeout = t;
	94	else
	95	ret = -EINVAL;
	96
	97	return ret;
	98	}
	99	EXPORT_SYMBOL_GPL(watchdog_init_timeout);
	100
43316044 WVS	101	/**
	102	* watchdog_register_device() - register a watchdog device
	103	* @wdd: watchdog device
	104	*
	105	* Register a watchdog device with the kernel so that the
	106	* watchdog timer can be accessed from userspace.
	107	*
	108	* A zero is returned on success and a negative errno code for
	109	* failure.
	110	*/
	111	int watchdog_register_device(struct watchdog_device *wdd)
	112	{
d6b469d9	113	int ret, id, devno;
43316044 WVS	114
	115	if (wdd == NULL \|\| wdd->info == NULL \|\| wdd->ops == NULL)
	116	return -EINVAL;
	117
	118	/* Mandatory operations need to be supported */
	119	if (wdd->ops->start == NULL \|\| wdd->ops->stop == NULL)
	120	return -EINVAL;
	121
3048253e	122	watchdog_check_min_max_timeout(wdd);
3f43f68e	123
43316044 WVS	124	/*
	125	* Note: now that all watchdog_device data has been verified, we
	126	* will not check this anymore in other functions. If data gets
	127	* corrupted in a later stage then we expect a kernel panic!
	128	*/
	129
f4e9c82f	130	mutex_init(&wdd->lock);
45f5fed3 AC	131	id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
	132	if (id < 0)
	133	return id;
	134	wdd->id = id;
	135
43316044 WVS	136	ret = watchdog_dev_register(wdd);
43316044 WVS	137	if (ret) {
45f5fed3 AC	138	ida_simple_remove(&watchdog_ida, id);
	139	if (!(id == 0 && ret == -EBUSY))
	140	return ret;
	141
	142	/* Retry in case a legacy watchdog module exists */
	143	id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
	144	if (id < 0)
	145	return id;
	146	wdd->id = id;
	147
	148	ret = watchdog_dev_register(wdd);
	149	if (ret) {
	150	ida_simple_remove(&watchdog_ida, id);
	151	return ret;
	152	}
43316044 WVS	153	}
43316044 WVS	154
d6b469d9 AC	155	devno = wdd->cdev.dev;
	156	wdd->dev = device_create(watchdog_class, wdd->parent, devno,
	157	NULL, "watchdog%d", wdd->id);
	158	if (IS_ERR(wdd->dev)) {
	159	watchdog_dev_unregister(wdd);
	160	ida_simple_remove(&watchdog_ida, id);
	161	ret = PTR_ERR(wdd->dev);
	162	return ret;
	163	}
	164
43316044 WVS	165	return 0;
	166	}
	167	EXPORT_SYMBOL_GPL(watchdog_register_device);
	168
	169	/**
	170	* watchdog_unregister_device() - unregister a watchdog device
	171	* @wdd: watchdog device to unregister
	172	*
	173	* Unregister a watchdog device that was previously successfully
	174	* registered with watchdog_register_device().
	175	*/
	176	void watchdog_unregister_device(struct watchdog_device *wdd)
	177	{
	178	int ret;
b232a70a	179	int devno;
43316044 WVS	180
	181	if (wdd == NULL)
	182	return;
	183
b232a70a	184	devno = wdd->cdev.dev;
43316044 WVS	185	ret = watchdog_dev_unregister(wdd);
43316044 WVS	186	if (ret)
27c766aa	187	pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
d6b469d9	188	device_destroy(watchdog_class, devno);
45f5fed3	189	ida_simple_remove(&watchdog_ida, wdd->id);
d6b469d9	190	wdd->dev = NULL;
43316044 WVS	191	}
	192	EXPORT_SYMBOL_GPL(watchdog_unregister_device);
	193
45f5fed3 AC	194	static int __init watchdog_init(void)
45f5fed3 AC	195	{
d6b469d9 AC	196	int err;
	197
	198	watchdog_class = class_create(THIS_MODULE, "watchdog");
	199	if (IS_ERR(watchdog_class)) {
	200	pr_err("couldn't create class\n");
	201	return PTR_ERR(watchdog_class);
	202	}
	203
	204	err = watchdog_dev_init();
	205	if (err < 0) {
	206	class_destroy(watchdog_class);
	207	return err;
	208	}
	209
	210	return 0;
45f5fed3 AC	211	}
	212
	213	static void __exit watchdog_exit(void)
	214	{
	215	watchdog_dev_exit();
d6b469d9	216	class_destroy(watchdog_class);
45f5fed3 AC	217	ida_destroy(&watchdog_ida);
	218	}
	219
	220	subsys_initcall(watchdog_init);
	221	module_exit(watchdog_exit);
	222
43316044 WVS	223	MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
	224	MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
	225	MODULE_DESCRIPTION("WatchDog Timer Driver Core");
	226	MODULE_LICENSE("GPL");