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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/... */
37
38#include "watchdog_dev.h" /* For watchdog_dev_register/... */
39
40/**
41 * watchdog_register_device() - register a watchdog device
42 * @wdd: watchdog device
43 *
44 * Register a watchdog device with the kernel so that the
45 * watchdog timer can be accessed from userspace.
46 *
47 * A zero is returned on success and a negative errno code for
48 * failure.
49 */
50int watchdog_register_device(struct watchdog_device *wdd)
51{
52 int ret;
53
54 if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
55 return -EINVAL;
56
57 /* Mandatory operations need to be supported */
58 if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
59 return -EINVAL;
60
61 /*
62 * Check that we have valid min and max timeout values, if
63 * not reset them both to 0 (=not used or unknown)
64 */
65 if (wdd->min_timeout > wdd->max_timeout) {
66 pr_info("Invalid min and max timeout values, resetting to 0!\n");
67 wdd->min_timeout = 0;
68 wdd->max_timeout = 0;
69 }
70
71 /*
72 * Note: now that all watchdog_device data has been verified, we
73 * will not check this anymore in other functions. If data gets
74 * corrupted in a later stage then we expect a kernel panic!
75 */
76
77 /* We only support 1 watchdog device via the /dev/watchdog interface */
78 ret = watchdog_dev_register(wdd);
79 if (ret) {
80 pr_err("error registering /dev/watchdog (err=%d).\n", ret);
81 return ret;
82 }
83
84 return 0;
85}
86EXPORT_SYMBOL_GPL(watchdog_register_device);
87
88/**
89 * watchdog_unregister_device() - unregister a watchdog device
90 * @wdd: watchdog device to unregister
91 *
92 * Unregister a watchdog device that was previously successfully
93 * registered with watchdog_register_device().
94 */
95void watchdog_unregister_device(struct watchdog_device *wdd)
96{
97 int ret;
98
99 if (wdd == NULL)
100 return;
101
102 ret = watchdog_dev_unregister(wdd);
103 if (ret)
104 pr_err("error unregistering /dev/watchdog (err=%d).\n", ret);
105}
106EXPORT_SYMBOL_GPL(watchdog_unregister_device);
107
108MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
109MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
110MODULE_DESCRIPTION("WatchDog Timer Driver Core");
111MODULE_LICENSE("GPL");
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");