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v5.9
  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 *	watchdog_core.c
  4 *
  5 *	(c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  6 *						All Rights Reserved.
  7 *
  8 *	(c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
  9 *
 10 *	This source code is part of the generic code that can be used
 11 *	by all the watchdog timer drivers.
 12 *
 13 *	Based on source code of the following authors:
 14 *	  Matt Domsch <Matt_Domsch@dell.com>,
 15 *	  Rob Radez <rob@osinvestor.com>,
 16 *	  Rusty Lynch <rusty@linux.co.intel.com>
 17 *	  Satyam Sharma <satyam@infradead.org>
 18 *	  Randy Dunlap <randy.dunlap@oracle.com>
 19 *
 20 *	Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
 21 *	admit liability nor provide warranty for any of this software.
 22 *	This material is provided "AS-IS" and at no charge.
 23 */
 24
 25#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 26
 27#include <linux/module.h>	/* For EXPORT_SYMBOL/module stuff/... */
 28#include <linux/types.h>	/* For standard types */
 29#include <linux/errno.h>	/* For the -ENODEV/... values */
 30#include <linux/kernel.h>	/* For printk/panic/... */
 31#include <linux/reboot.h>	/* For restart handler */
 32#include <linux/watchdog.h>	/* For watchdog specific items */
 33#include <linux/init.h>		/* For __init/__exit/... */
 34#include <linux/idr.h>		/* For ida_* macros */
 35#include <linux/err.h>		/* For IS_ERR macros */
 36#include <linux/of.h>		/* For of_get_timeout_sec */
 
 37
 38#include "watchdog_core.h"	/* For watchdog_dev_register/... */
 39
 
 
 
 40static DEFINE_IDA(watchdog_ida);
 41
 42static int stop_on_reboot = -1;
 43module_param(stop_on_reboot, int, 0444);
 44MODULE_PARM_DESC(stop_on_reboot, "Stop watchdogs on reboot (0=keep watching, 1=stop)");
 45
 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
 59static DEFINE_MUTEX(wtd_deferred_reg_mutex);
 60static LIST_HEAD(wtd_deferred_reg_list);
 61static bool wtd_deferred_reg_done;
 62
 63static void watchdog_deferred_registration_add(struct watchdog_device *wdd)
 64{
 65	list_add_tail(&wdd->deferred,
 66		      &wtd_deferred_reg_list);
 67}
 68
 69static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
 70{
 71	struct list_head *p, *n;
 72	struct watchdog_device *wdd_tmp;
 73
 74	list_for_each_safe(p, n, &wtd_deferred_reg_list) {
 75		wdd_tmp = list_entry(p, struct watchdog_device,
 76				     deferred);
 77		if (wdd_tmp == wdd) {
 78			list_del(&wdd_tmp->deferred);
 79			break;
 80		}
 81	}
 82}
 83
 84static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
 85{
 86	/*
 87	 * Check that we have valid min and max timeout values, if
 88	 * not reset them both to 0 (=not used or unknown)
 89	 */
 90	if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {
 91		pr_info("Invalid min and max timeout values, resetting to 0!\n");
 92		wdd->min_timeout = 0;
 93		wdd->max_timeout = 0;
 94	}
 95}
 96
 97/**
 98 * watchdog_init_timeout() - initialize the timeout field
 99 * @wdd: watchdog device
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). Note that for the module parameter, '0' means
108 * 'use default' while it is an invalid value for the timeout-sec property.
109 * It should simply be dropped if you want to use the default value then.
110 *
111 * A zero is returned on success or -EINVAL if all provided values are out of
112 * bounds.
113 */
114int watchdog_init_timeout(struct watchdog_device *wdd,
115				unsigned int timeout_parm, struct device *dev)
116{
117	const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
118			      (const char *)wdd->info->identity;
119	unsigned int t = 0;
120	int ret = 0;
121
122	watchdog_check_min_max_timeout(wdd);
123
124	/* check the driver supplied value (likely a module parameter) first */
125	if (timeout_parm) {
126		if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
127			wdd->timeout = timeout_parm;
128			return 0;
129		}
130		pr_err("%s: driver supplied timeout (%u) out of range\n",
131			dev_str, timeout_parm);
132		ret = -EINVAL;
133	}
134
135	/* try to get the timeout_sec property */
136	if (dev && dev->of_node &&
137	    of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) {
138		if (t && !watchdog_timeout_invalid(wdd, t)) {
139			wdd->timeout = t;
140			return 0;
141		}
142		pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t);
143		ret = -EINVAL;
144	}
145
146	if (ret < 0 && wdd->timeout)
147		pr_warn("%s: falling back to default timeout (%u)\n", dev_str,
148			wdd->timeout);
149
150	return ret;
151}
152EXPORT_SYMBOL_GPL(watchdog_init_timeout);
153
154static int watchdog_reboot_notifier(struct notifier_block *nb,
155				    unsigned long code, void *data)
156{
157	struct watchdog_device *wdd;
158
159	wdd = container_of(nb, struct watchdog_device, reboot_nb);
160	if (code == SYS_DOWN || code == SYS_HALT) {
161		if (watchdog_active(wdd)) {
162			int ret;
163
164			ret = wdd->ops->stop(wdd);
 
165			if (ret)
166				return NOTIFY_BAD;
167		}
168	}
169
170	return NOTIFY_DONE;
171}
172
173static int watchdog_restart_notifier(struct notifier_block *nb,
174				     unsigned long action, void *data)
175{
176	struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
177						   restart_nb);
178
179	int ret;
180
181	ret = wdd->ops->restart(wdd, action, data);
182	if (ret)
183		return NOTIFY_BAD;
184
185	return NOTIFY_DONE;
186}
187
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
188/**
189 * watchdog_set_restart_priority - Change priority of restart handler
190 * @wdd: watchdog device
191 * @priority: priority of the restart handler, should follow these guidelines:
192 *   0:   use watchdog's restart function as last resort, has limited restart
193 *        capabilies
194 *   128: default restart handler, use if no other handler is expected to be
195 *        available and/or if restart is sufficient to restart the entire system
196 *   255: preempt all other handlers
197 *
198 * If a wdd->ops->restart function is provided when watchdog_register_device is
199 * called, it will be registered as a restart handler with the priority given
200 * here.
201 */
202void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
203{
204	wdd->restart_nb.priority = priority;
205}
206EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
207
208static int __watchdog_register_device(struct watchdog_device *wdd)
209{
210	int ret, id = -1;
211
212	if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
213		return -EINVAL;
214
215	/* Mandatory operations need to be supported */
216	if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
217		return -EINVAL;
218
219	watchdog_check_min_max_timeout(wdd);
220
221	/*
222	 * Note: now that all watchdog_device data has been verified, we
223	 * will not check this anymore in other functions. If data gets
224	 * corrupted in a later stage then we expect a kernel panic!
225	 */
226
227	/* Use alias for watchdog id if possible */
228	if (wdd->parent) {
229		ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
230		if (ret >= 0)
231			id = ida_simple_get(&watchdog_ida, ret,
232					    ret + 1, GFP_KERNEL);
233	}
234
235	if (id < 0)
236		id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
237
238	if (id < 0)
239		return id;
240	wdd->id = id;
241
242	ret = watchdog_dev_register(wdd);
243	if (ret) {
244		ida_simple_remove(&watchdog_ida, id);
245		if (!(id == 0 && ret == -EBUSY))
246			return ret;
247
248		/* Retry in case a legacy watchdog module exists */
249		id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
250		if (id < 0)
251			return id;
252		wdd->id = id;
253
254		ret = watchdog_dev_register(wdd);
255		if (ret) {
256			ida_simple_remove(&watchdog_ida, id);
257			return ret;
258		}
259	}
260
261	/* Module parameter to force watchdog policy on reboot. */
262	if (stop_on_reboot != -1) {
263		if (stop_on_reboot)
264			set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
265		else
266			clear_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
267	}
268
269	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
270		wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
271
272		ret = register_reboot_notifier(&wdd->reboot_nb);
273		if (ret) {
274			pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
275			       wdd->id, ret);
276			watchdog_dev_unregister(wdd);
277			ida_simple_remove(&watchdog_ida, id);
278			return ret;
 
 
 
 
279		}
280	}
281
282	if (wdd->ops->restart) {
283		wdd->restart_nb.notifier_call = watchdog_restart_notifier;
284
285		ret = register_restart_handler(&wdd->restart_nb);
286		if (ret)
287			pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
 
 
 
 
 
 
 
 
 
288				wdd->id, ret);
289	}
290
291	return 0;
292}
293
294/**
295 * watchdog_register_device() - register a watchdog device
296 * @wdd: watchdog device
297 *
298 * Register a watchdog device with the kernel so that the
299 * watchdog timer can be accessed from userspace.
300 *
301 * A zero is returned on success and a negative errno code for
302 * failure.
303 */
304
305int watchdog_register_device(struct watchdog_device *wdd)
306{
307	const char *dev_str;
308	int ret = 0;
309
310	mutex_lock(&wtd_deferred_reg_mutex);
311	if (wtd_deferred_reg_done)
312		ret = __watchdog_register_device(wdd);
313	else
314		watchdog_deferred_registration_add(wdd);
315	mutex_unlock(&wtd_deferred_reg_mutex);
316
317	if (ret) {
318		dev_str = wdd->parent ? dev_name(wdd->parent) :
319			  (const char *)wdd->info->identity;
320		pr_err("%s: failed to register watchdog device (err = %d)\n",
321			dev_str, ret);
322	}
323
324	return ret;
325}
326EXPORT_SYMBOL_GPL(watchdog_register_device);
327
328static void __watchdog_unregister_device(struct watchdog_device *wdd)
329{
330	if (wdd == NULL)
331		return;
332
333	if (wdd->ops->restart)
334		unregister_restart_handler(&wdd->restart_nb);
335
336	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
337		unregister_reboot_notifier(&wdd->reboot_nb);
338
339	watchdog_dev_unregister(wdd);
340	ida_simple_remove(&watchdog_ida, wdd->id);
341}
342
343/**
344 * watchdog_unregister_device() - unregister a watchdog device
345 * @wdd: watchdog device to unregister
346 *
347 * Unregister a watchdog device that was previously successfully
348 * registered with watchdog_register_device().
349 */
350
351void watchdog_unregister_device(struct watchdog_device *wdd)
352{
353	mutex_lock(&wtd_deferred_reg_mutex);
354	if (wtd_deferred_reg_done)
355		__watchdog_unregister_device(wdd);
356	else
357		watchdog_deferred_registration_del(wdd);
358	mutex_unlock(&wtd_deferred_reg_mutex);
359}
360
361EXPORT_SYMBOL_GPL(watchdog_unregister_device);
362
363static void devm_watchdog_unregister_device(struct device *dev, void *res)
364{
365	watchdog_unregister_device(*(struct watchdog_device **)res);
366}
367
368/**
369 * devm_watchdog_register_device() - resource managed watchdog_register_device()
370 * @dev: device that is registering this watchdog device
371 * @wdd: watchdog device
372 *
373 * Managed watchdog_register_device(). For watchdog device registered by this
374 * function,  watchdog_unregister_device() is automatically called on driver
375 * detach. See watchdog_register_device() for more information.
376 */
377int devm_watchdog_register_device(struct device *dev,
378				struct watchdog_device *wdd)
379{
380	struct watchdog_device **rcwdd;
381	int ret;
382
383	rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
384			     GFP_KERNEL);
385	if (!rcwdd)
386		return -ENOMEM;
387
388	ret = watchdog_register_device(wdd);
389	if (!ret) {
390		*rcwdd = wdd;
391		devres_add(dev, rcwdd);
392	} else {
393		devres_free(rcwdd);
394	}
395
396	return ret;
397}
398EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
399
400static int __init watchdog_deferred_registration(void)
401{
402	mutex_lock(&wtd_deferred_reg_mutex);
403	wtd_deferred_reg_done = true;
404	while (!list_empty(&wtd_deferred_reg_list)) {
405		struct watchdog_device *wdd;
406
407		wdd = list_first_entry(&wtd_deferred_reg_list,
408				       struct watchdog_device, deferred);
409		list_del(&wdd->deferred);
410		__watchdog_register_device(wdd);
411	}
412	mutex_unlock(&wtd_deferred_reg_mutex);
413	return 0;
414}
415
416static int __init watchdog_init(void)
417{
418	int err;
419
420	err = watchdog_dev_init();
421	if (err < 0)
422		return err;
423
424	watchdog_deferred_registration();
425	return 0;
426}
427
428static void __exit watchdog_exit(void)
429{
430	watchdog_dev_exit();
431	ida_destroy(&watchdog_ida);
432}
433
434subsys_initcall_sync(watchdog_init);
435module_exit(watchdog_exit);
436
437MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
438MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
439MODULE_DESCRIPTION("WatchDog Timer Driver Core");
440MODULE_LICENSE("GPL");
v6.2
  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 *	watchdog_core.c
  4 *
  5 *	(c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  6 *						All Rights Reserved.
  7 *
  8 *	(c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
  9 *
 10 *	This source code is part of the generic code that can be used
 11 *	by all the watchdog timer drivers.
 12 *
 13 *	Based on source code of the following authors:
 14 *	  Matt Domsch <Matt_Domsch@dell.com>,
 15 *	  Rob Radez <rob@osinvestor.com>,
 16 *	  Rusty Lynch <rusty@linux.co.intel.com>
 17 *	  Satyam Sharma <satyam@infradead.org>
 18 *	  Randy Dunlap <randy.dunlap@oracle.com>
 19 *
 20 *	Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
 21 *	admit liability nor provide warranty for any of this software.
 22 *	This material is provided "AS-IS" and at no charge.
 23 */
 24
 25#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 26
 27#include <linux/module.h>	/* For EXPORT_SYMBOL/module stuff/... */
 28#include <linux/types.h>	/* For standard types */
 29#include <linux/errno.h>	/* For the -ENODEV/... values */
 30#include <linux/kernel.h>	/* For printk/panic/... */
 31#include <linux/reboot.h>	/* For restart handler */
 32#include <linux/watchdog.h>	/* For watchdog specific items */
 33#include <linux/init.h>		/* For __init/__exit/... */
 34#include <linux/idr.h>		/* For ida_* macros */
 35#include <linux/err.h>		/* For IS_ERR macros */
 36#include <linux/of.h>		/* For of_get_timeout_sec */
 37#include <linux/suspend.h>
 38
 39#include "watchdog_core.h"	/* For watchdog_dev_register/... */
 40
 41#define CREATE_TRACE_POINTS
 42#include <trace/events/watchdog.h>
 43
 44static DEFINE_IDA(watchdog_ida);
 45
 46static int stop_on_reboot = -1;
 47module_param(stop_on_reboot, int, 0444);
 48MODULE_PARM_DESC(stop_on_reboot, "Stop watchdogs on reboot (0=keep watching, 1=stop)");
 49
 50/*
 51 * Deferred Registration infrastructure.
 52 *
 53 * Sometimes watchdog drivers needs to be loaded as soon as possible,
 54 * for example when it's impossible to disable it. To do so,
 55 * raising the initcall level of the watchdog driver is a solution.
 56 * But in such case, the miscdev is maybe not ready (subsys_initcall), and
 57 * watchdog_core need miscdev to register the watchdog as a char device.
 58 *
 59 * The deferred registration infrastructure offer a way for the watchdog
 60 * subsystem to register a watchdog properly, even before miscdev is ready.
 61 */
 62
 63static DEFINE_MUTEX(wtd_deferred_reg_mutex);
 64static LIST_HEAD(wtd_deferred_reg_list);
 65static bool wtd_deferred_reg_done;
 66
 67static void watchdog_deferred_registration_add(struct watchdog_device *wdd)
 68{
 69	list_add_tail(&wdd->deferred,
 70		      &wtd_deferred_reg_list);
 71}
 72
 73static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
 74{
 75	struct list_head *p, *n;
 76	struct watchdog_device *wdd_tmp;
 77
 78	list_for_each_safe(p, n, &wtd_deferred_reg_list) {
 79		wdd_tmp = list_entry(p, struct watchdog_device,
 80				     deferred);
 81		if (wdd_tmp == wdd) {
 82			list_del(&wdd_tmp->deferred);
 83			break;
 84		}
 85	}
 86}
 87
 88static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
 89{
 90	/*
 91	 * Check that we have valid min and max timeout values, if
 92	 * not reset them both to 0 (=not used or unknown)
 93	 */
 94	if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {
 95		pr_info("Invalid min and max timeout values, resetting to 0!\n");
 96		wdd->min_timeout = 0;
 97		wdd->max_timeout = 0;
 98	}
 99}
100
101/**
102 * watchdog_init_timeout() - initialize the timeout field
103 * @wdd: watchdog device
104 * @timeout_parm: timeout module parameter
105 * @dev: Device that stores the timeout-sec property
106 *
107 * Initialize the timeout field of the watchdog_device struct with either the
108 * timeout module parameter (if it is valid value) or the timeout-sec property
109 * (only if it is a valid value and the timeout_parm is out of bounds).
110 * If none of them are valid then we keep the old value (which should normally
111 * be the default timeout value). Note that for the module parameter, '0' means
112 * 'use default' while it is an invalid value for the timeout-sec property.
113 * It should simply be dropped if you want to use the default value then.
114 *
115 * A zero is returned on success or -EINVAL if all provided values are out of
116 * bounds.
117 */
118int watchdog_init_timeout(struct watchdog_device *wdd,
119				unsigned int timeout_parm, struct device *dev)
120{
121	const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
122			      (const char *)wdd->info->identity;
123	unsigned int t = 0;
124	int ret = 0;
125
126	watchdog_check_min_max_timeout(wdd);
127
128	/* check the driver supplied value (likely a module parameter) first */
129	if (timeout_parm) {
130		if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
131			wdd->timeout = timeout_parm;
132			return 0;
133		}
134		pr_err("%s: driver supplied timeout (%u) out of range\n",
135			dev_str, timeout_parm);
136		ret = -EINVAL;
137	}
138
139	/* try to get the timeout_sec property */
140	if (dev && dev->of_node &&
141	    of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) {
142		if (t && !watchdog_timeout_invalid(wdd, t)) {
143			wdd->timeout = t;
144			return 0;
145		}
146		pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t);
147		ret = -EINVAL;
148	}
149
150	if (ret < 0 && wdd->timeout)
151		pr_warn("%s: falling back to default timeout (%u)\n", dev_str,
152			wdd->timeout);
153
154	return ret;
155}
156EXPORT_SYMBOL_GPL(watchdog_init_timeout);
157
158static int watchdog_reboot_notifier(struct notifier_block *nb,
159				    unsigned long code, void *data)
160{
161	struct watchdog_device *wdd;
162
163	wdd = container_of(nb, struct watchdog_device, reboot_nb);
164	if (code == SYS_DOWN || code == SYS_HALT) {
165		if (watchdog_active(wdd) || watchdog_hw_running(wdd)) {
166			int ret;
167
168			ret = wdd->ops->stop(wdd);
169			trace_watchdog_stop(wdd, ret);
170			if (ret)
171				return NOTIFY_BAD;
172		}
173	}
174
175	return NOTIFY_DONE;
176}
177
178static int watchdog_restart_notifier(struct notifier_block *nb,
179				     unsigned long action, void *data)
180{
181	struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
182						   restart_nb);
183
184	int ret;
185
186	ret = wdd->ops->restart(wdd, action, data);
187	if (ret)
188		return NOTIFY_BAD;
189
190	return NOTIFY_DONE;
191}
192
193static int watchdog_pm_notifier(struct notifier_block *nb, unsigned long mode,
194				void *data)
195{
196	struct watchdog_device *wdd;
197	int ret = 0;
198
199	wdd = container_of(nb, struct watchdog_device, pm_nb);
200
201	switch (mode) {
202	case PM_HIBERNATION_PREPARE:
203	case PM_RESTORE_PREPARE:
204	case PM_SUSPEND_PREPARE:
205		ret = watchdog_dev_suspend(wdd);
206		break;
207	case PM_POST_HIBERNATION:
208	case PM_POST_RESTORE:
209	case PM_POST_SUSPEND:
210		ret = watchdog_dev_resume(wdd);
211		break;
212	}
213
214	if (ret)
215		return NOTIFY_BAD;
216
217	return NOTIFY_DONE;
218}
219
220/**
221 * watchdog_set_restart_priority - Change priority of restart handler
222 * @wdd: watchdog device
223 * @priority: priority of the restart handler, should follow these guidelines:
224 *   0:   use watchdog's restart function as last resort, has limited restart
225 *        capabilies
226 *   128: default restart handler, use if no other handler is expected to be
227 *        available and/or if restart is sufficient to restart the entire system
228 *   255: preempt all other handlers
229 *
230 * If a wdd->ops->restart function is provided when watchdog_register_device is
231 * called, it will be registered as a restart handler with the priority given
232 * here.
233 */
234void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
235{
236	wdd->restart_nb.priority = priority;
237}
238EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
239
240static int __watchdog_register_device(struct watchdog_device *wdd)
241{
242	int ret, id = -1;
243
244	if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
245		return -EINVAL;
246
247	/* Mandatory operations need to be supported */
248	if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
249		return -EINVAL;
250
251	watchdog_check_min_max_timeout(wdd);
252
253	/*
254	 * Note: now that all watchdog_device data has been verified, we
255	 * will not check this anymore in other functions. If data gets
256	 * corrupted in a later stage then we expect a kernel panic!
257	 */
258
259	/* Use alias for watchdog id if possible */
260	if (wdd->parent) {
261		ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
262		if (ret >= 0)
263			id = ida_simple_get(&watchdog_ida, ret,
264					    ret + 1, GFP_KERNEL);
265	}
266
267	if (id < 0)
268		id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
269
270	if (id < 0)
271		return id;
272	wdd->id = id;
273
274	ret = watchdog_dev_register(wdd);
275	if (ret) {
276		ida_simple_remove(&watchdog_ida, id);
277		if (!(id == 0 && ret == -EBUSY))
278			return ret;
279
280		/* Retry in case a legacy watchdog module exists */
281		id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
282		if (id < 0)
283			return id;
284		wdd->id = id;
285
286		ret = watchdog_dev_register(wdd);
287		if (ret) {
288			ida_simple_remove(&watchdog_ida, id);
289			return ret;
290		}
291	}
292
293	/* Module parameter to force watchdog policy on reboot. */
294	if (stop_on_reboot != -1) {
295		if (stop_on_reboot)
296			set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
297		else
298			clear_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
299	}
300
301	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
302		if (!wdd->ops->stop)
303			pr_warn("watchdog%d: stop_on_reboot not supported\n", wdd->id);
304		else {
305			wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
306
307			ret = register_reboot_notifier(&wdd->reboot_nb);
308			if (ret) {
309				pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
310					wdd->id, ret);
311				watchdog_dev_unregister(wdd);
312				ida_simple_remove(&watchdog_ida, id);
313				return ret;
314			}
315		}
316	}
317
318	if (wdd->ops->restart) {
319		wdd->restart_nb.notifier_call = watchdog_restart_notifier;
320
321		ret = register_restart_handler(&wdd->restart_nb);
322		if (ret)
323			pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
324				wdd->id, ret);
325	}
326
327	if (test_bit(WDOG_NO_PING_ON_SUSPEND, &wdd->status)) {
328		wdd->pm_nb.notifier_call = watchdog_pm_notifier;
329
330		ret = register_pm_notifier(&wdd->pm_nb);
331		if (ret)
332			pr_warn("watchdog%d: Cannot register pm handler (%d)\n",
333				wdd->id, ret);
334	}
335
336	return 0;
337}
338
339/**
340 * watchdog_register_device() - register a watchdog device
341 * @wdd: watchdog device
342 *
343 * Register a watchdog device with the kernel so that the
344 * watchdog timer can be accessed from userspace.
345 *
346 * A zero is returned on success and a negative errno code for
347 * failure.
348 */
349
350int watchdog_register_device(struct watchdog_device *wdd)
351{
352	const char *dev_str;
353	int ret = 0;
354
355	mutex_lock(&wtd_deferred_reg_mutex);
356	if (wtd_deferred_reg_done)
357		ret = __watchdog_register_device(wdd);
358	else
359		watchdog_deferred_registration_add(wdd);
360	mutex_unlock(&wtd_deferred_reg_mutex);
361
362	if (ret) {
363		dev_str = wdd->parent ? dev_name(wdd->parent) :
364			  (const char *)wdd->info->identity;
365		pr_err("%s: failed to register watchdog device (err = %d)\n",
366			dev_str, ret);
367	}
368
369	return ret;
370}
371EXPORT_SYMBOL_GPL(watchdog_register_device);
372
373static void __watchdog_unregister_device(struct watchdog_device *wdd)
374{
375	if (wdd == NULL)
376		return;
377
378	if (wdd->ops->restart)
379		unregister_restart_handler(&wdd->restart_nb);
380
381	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
382		unregister_reboot_notifier(&wdd->reboot_nb);
383
384	watchdog_dev_unregister(wdd);
385	ida_simple_remove(&watchdog_ida, wdd->id);
386}
387
388/**
389 * watchdog_unregister_device() - unregister a watchdog device
390 * @wdd: watchdog device to unregister
391 *
392 * Unregister a watchdog device that was previously successfully
393 * registered with watchdog_register_device().
394 */
395
396void watchdog_unregister_device(struct watchdog_device *wdd)
397{
398	mutex_lock(&wtd_deferred_reg_mutex);
399	if (wtd_deferred_reg_done)
400		__watchdog_unregister_device(wdd);
401	else
402		watchdog_deferred_registration_del(wdd);
403	mutex_unlock(&wtd_deferred_reg_mutex);
404}
405
406EXPORT_SYMBOL_GPL(watchdog_unregister_device);
407
408static void devm_watchdog_unregister_device(struct device *dev, void *res)
409{
410	watchdog_unregister_device(*(struct watchdog_device **)res);
411}
412
413/**
414 * devm_watchdog_register_device() - resource managed watchdog_register_device()
415 * @dev: device that is registering this watchdog device
416 * @wdd: watchdog device
417 *
418 * Managed watchdog_register_device(). For watchdog device registered by this
419 * function,  watchdog_unregister_device() is automatically called on driver
420 * detach. See watchdog_register_device() for more information.
421 */
422int devm_watchdog_register_device(struct device *dev,
423				struct watchdog_device *wdd)
424{
425	struct watchdog_device **rcwdd;
426	int ret;
427
428	rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
429			     GFP_KERNEL);
430	if (!rcwdd)
431		return -ENOMEM;
432
433	ret = watchdog_register_device(wdd);
434	if (!ret) {
435		*rcwdd = wdd;
436		devres_add(dev, rcwdd);
437	} else {
438		devres_free(rcwdd);
439	}
440
441	return ret;
442}
443EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
444
445static int __init watchdog_deferred_registration(void)
446{
447	mutex_lock(&wtd_deferred_reg_mutex);
448	wtd_deferred_reg_done = true;
449	while (!list_empty(&wtd_deferred_reg_list)) {
450		struct watchdog_device *wdd;
451
452		wdd = list_first_entry(&wtd_deferred_reg_list,
453				       struct watchdog_device, deferred);
454		list_del(&wdd->deferred);
455		__watchdog_register_device(wdd);
456	}
457	mutex_unlock(&wtd_deferred_reg_mutex);
458	return 0;
459}
460
461static int __init watchdog_init(void)
462{
463	int err;
464
465	err = watchdog_dev_init();
466	if (err < 0)
467		return err;
468
469	watchdog_deferred_registration();
470	return 0;
471}
472
473static void __exit watchdog_exit(void)
474{
475	watchdog_dev_exit();
476	ida_destroy(&watchdog_ida);
477}
478
479subsys_initcall_sync(watchdog_init);
480module_exit(watchdog_exit);
481
482MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
483MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
484MODULE_DESCRIPTION("WatchDog Timer Driver Core");
485MODULE_LICENSE("GPL");