4 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
7 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
9 * This source code is part of the generic code that can be used
10 * by all the watchdog timer drivers.
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>
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.
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.
29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/reboot.h> /* For restart handler */
36 #include <linux/watchdog.h> /* For watchdog specific items */
37 #include <linux/init.h> /* For __init/__exit/... */
38 #include <linux/idr.h> /* For ida_* macros */
39 #include <linux/err.h> /* For IS_ERR macros */
40 #include <linux/of.h> /* For of_get_timeout_sec */
42 #include "watchdog_core.h" /* For watchdog_dev_register/... */
44 static DEFINE_IDA(watchdog_ida);
47 * Deferred Registration infrastructure.
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.
55 * The deferred registration infrastructure offer a way for the watchdog
56 * subsystem to register a watchdog properly, even before miscdev is ready.
59 static DEFINE_MUTEX(wtd_deferred_reg_mutex);
60 static LIST_HEAD(wtd_deferred_reg_list);
61 static bool wtd_deferred_reg_done;
63 static int watchdog_deferred_registration_add(struct watchdog_device *wdd)
65 list_add_tail(&wdd->deferred,
66 &wtd_deferred_reg_list);
70 static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
72 struct list_head *p, *n;
73 struct watchdog_device *wdd_tmp;
75 list_for_each_safe(p, n, &wtd_deferred_reg_list) {
76 wdd_tmp = list_entry(p, struct watchdog_device,
79 list_del(&wdd_tmp->deferred);
85 static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
88 * Check that we have valid min and max timeout values, if
89 * not reset them both to 0 (=not used or unknown)
91 if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {
92 pr_info("Invalid min and max timeout values, resetting to 0!\n");
99 * watchdog_init_timeout() - initialize the timeout field
100 * @wdd: watchdog device
101 * @timeout_parm: timeout module parameter
102 * @dev: Device that stores the timeout-sec property
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
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.
112 * A zero is returned on success or -EINVAL if all provided values are out of
115 int watchdog_init_timeout(struct watchdog_device *wdd,
116 unsigned int timeout_parm, struct device *dev)
118 const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
119 (const char *)wdd->info->identity;
123 watchdog_check_min_max_timeout(wdd);
125 /* check the driver supplied value (likely a module parameter) first */
127 if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
128 wdd->timeout = timeout_parm;
131 pr_err("%s: driver supplied timeout (%u) out of range\n",
132 dev_str, timeout_parm);
136 /* try to get the timeout_sec property */
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)) {
143 pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t);
147 if (ret < 0 && wdd->timeout)
148 pr_warn("%s: falling back to default timeout (%u)\n", dev_str,
153 EXPORT_SYMBOL_GPL(watchdog_init_timeout);
155 static int watchdog_restart_notifier(struct notifier_block *nb,
156 unsigned long action, void *data)
158 struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
163 ret = wdd->ops->restart(wdd, action, data);
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
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
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
184 void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
186 wdd->restart_nb.priority = priority;
188 EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
190 static int __watchdog_register_device(struct watchdog_device *wdd)
194 if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
197 /* Mandatory operations need to be supported */
198 if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
201 watchdog_check_min_max_timeout(wdd);
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!
209 /* Use alias for watchdog id if possible */
211 ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
213 id = ida_simple_get(&watchdog_ida, ret,
214 ret + 1, GFP_KERNEL);
218 id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
224 ret = watchdog_dev_register(wdd);
226 ida_simple_remove(&watchdog_ida, id);
227 if (!(id == 0 && ret == -EBUSY))
230 /* Retry in case a legacy watchdog module exists */
231 id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
236 ret = watchdog_dev_register(wdd);
238 ida_simple_remove(&watchdog_ida, id);
243 if (wdd->ops->restart) {
244 wdd->restart_nb.notifier_call = watchdog_restart_notifier;
246 ret = register_restart_handler(&wdd->restart_nb);
248 pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
256 * watchdog_register_device() - register a watchdog device
257 * @wdd: watchdog device
259 * Register a watchdog device with the kernel so that the
260 * watchdog timer can be accessed from userspace.
262 * A zero is returned on success and a negative errno code for
266 int watchdog_register_device(struct watchdog_device *wdd)
270 mutex_lock(&wtd_deferred_reg_mutex);
271 if (wtd_deferred_reg_done)
272 ret = __watchdog_register_device(wdd);
274 ret = watchdog_deferred_registration_add(wdd);
275 mutex_unlock(&wtd_deferred_reg_mutex);
278 EXPORT_SYMBOL_GPL(watchdog_register_device);
280 static void __watchdog_unregister_device(struct watchdog_device *wdd)
285 if (wdd->ops->restart)
286 unregister_restart_handler(&wdd->restart_nb);
288 watchdog_dev_unregister(wdd);
289 ida_simple_remove(&watchdog_ida, wdd->id);
293 * watchdog_unregister_device() - unregister a watchdog device
294 * @wdd: watchdog device to unregister
296 * Unregister a watchdog device that was previously successfully
297 * registered with watchdog_register_device().
300 void watchdog_unregister_device(struct watchdog_device *wdd)
302 mutex_lock(&wtd_deferred_reg_mutex);
303 if (wtd_deferred_reg_done)
304 __watchdog_unregister_device(wdd);
306 watchdog_deferred_registration_del(wdd);
307 mutex_unlock(&wtd_deferred_reg_mutex);
310 EXPORT_SYMBOL_GPL(watchdog_unregister_device);
312 static void devm_watchdog_unregister_device(struct device *dev, void *res)
314 watchdog_unregister_device(*(struct watchdog_device **)res);
318 * devm_watchdog_register_device() - resource managed watchdog_register_device()
319 * @dev: device that is registering this watchdog device
320 * @wdd: watchdog device
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.
326 int devm_watchdog_register_device(struct device *dev,
327 struct watchdog_device *wdd)
329 struct watchdog_device **rcwdd;
332 rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
337 ret = watchdog_register_device(wdd);
340 devres_add(dev, rcwdd);
347 EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
349 static int __init watchdog_deferred_registration(void)
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;
356 wdd = list_first_entry(&wtd_deferred_reg_list,
357 struct watchdog_device, deferred);
358 list_del(&wdd->deferred);
359 __watchdog_register_device(wdd);
361 mutex_unlock(&wtd_deferred_reg_mutex);
365 static int __init watchdog_init(void)
369 err = watchdog_dev_init();
373 watchdog_deferred_registration();
377 static void __exit watchdog_exit(void)
380 ida_destroy(&watchdog_ida);
383 subsys_initcall_sync(watchdog_init);
384 module_exit(watchdog_exit);
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");