Loading...
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/*
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/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 */
41
42#include "watchdog_core.h" /* For watchdog_dev_register/... */
43
44static DEFINE_IDA(watchdog_ida);
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 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
70static 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
85static 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->max_hw_heartbeat_ms && 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 * @wdd: watchdog device
101 * @timeout_parm: timeout module parameter
102 * @dev: Device that stores the timeout-sec property
103 *
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).
109 *
110 * A zero is returned on success and -EINVAL for failure.
111 */
112int watchdog_init_timeout(struct watchdog_device *wdd,
113 unsigned int timeout_parm, struct device *dev)
114{
115 unsigned int t = 0;
116 int ret = 0;
117
118 watchdog_check_min_max_timeout(wdd);
119
120 /* try to get the timeout module parameter first */
121 if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
122 wdd->timeout = timeout_parm;
123 return ret;
124 }
125 if (timeout_parm)
126 ret = -EINVAL;
127
128 /* try to get the timeout_sec property */
129 if (dev == NULL || dev->of_node == NULL)
130 return ret;
131 of_property_read_u32(dev->of_node, "timeout-sec", &t);
132 if (!watchdog_timeout_invalid(wdd, t) && t)
133 wdd->timeout = t;
134 else
135 ret = -EINVAL;
136
137 return ret;
138}
139EXPORT_SYMBOL_GPL(watchdog_init_timeout);
140
141static int watchdog_restart_notifier(struct notifier_block *nb,
142 unsigned long action, void *data)
143{
144 struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
145 restart_nb);
146
147 int ret;
148
149 ret = wdd->ops->restart(wdd, action, data);
150 if (ret)
151 return NOTIFY_BAD;
152
153 return NOTIFY_DONE;
154}
155
156/**
157 * watchdog_set_restart_priority - Change priority of restart handler
158 * @wdd: watchdog device
159 * @priority: priority of the restart handler, should follow these guidelines:
160 * 0: use watchdog's restart function as last resort, has limited restart
161 * capabilies
162 * 128: default restart handler, use if no other handler is expected to be
163 * available and/or if restart is sufficient to restart the entire system
164 * 255: preempt all other handlers
165 *
166 * If a wdd->ops->restart function is provided when watchdog_register_device is
167 * called, it will be registered as a restart handler with the priority given
168 * here.
169 */
170void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
171{
172 wdd->restart_nb.priority = priority;
173}
174EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
175
176static int __watchdog_register_device(struct watchdog_device *wdd)
177{
178 int ret, id = -1;
179
180 if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
181 return -EINVAL;
182
183 /* Mandatory operations need to be supported */
184 if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
185 return -EINVAL;
186
187 watchdog_check_min_max_timeout(wdd);
188
189 /*
190 * Note: now that all watchdog_device data has been verified, we
191 * will not check this anymore in other functions. If data gets
192 * corrupted in a later stage then we expect a kernel panic!
193 */
194
195 /* Use alias for watchdog id if possible */
196 if (wdd->parent) {
197 ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
198 if (ret >= 0)
199 id = ida_simple_get(&watchdog_ida, ret,
200 ret + 1, GFP_KERNEL);
201 }
202
203 if (id < 0)
204 id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
205
206 if (id < 0)
207 return id;
208 wdd->id = id;
209
210 ret = watchdog_dev_register(wdd);
211 if (ret) {
212 ida_simple_remove(&watchdog_ida, id);
213 if (!(id == 0 && ret == -EBUSY))
214 return ret;
215
216 /* Retry in case a legacy watchdog module exists */
217 id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
218 if (id < 0)
219 return id;
220 wdd->id = id;
221
222 ret = watchdog_dev_register(wdd);
223 if (ret) {
224 ida_simple_remove(&watchdog_ida, id);
225 return ret;
226 }
227 }
228
229 if (wdd->ops->restart) {
230 wdd->restart_nb.notifier_call = watchdog_restart_notifier;
231
232 ret = register_restart_handler(&wdd->restart_nb);
233 if (ret)
234 pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
235 wdd->id, ret);
236 }
237
238 return 0;
239}
240
241/**
242 * watchdog_register_device() - register a watchdog device
243 * @wdd: watchdog device
244 *
245 * Register a watchdog device with the kernel so that the
246 * watchdog timer can be accessed from userspace.
247 *
248 * A zero is returned on success and a negative errno code for
249 * failure.
250 */
251
252int watchdog_register_device(struct watchdog_device *wdd)
253{
254 int ret;
255
256 mutex_lock(&wtd_deferred_reg_mutex);
257 if (wtd_deferred_reg_done)
258 ret = __watchdog_register_device(wdd);
259 else
260 ret = watchdog_deferred_registration_add(wdd);
261 mutex_unlock(&wtd_deferred_reg_mutex);
262 return ret;
263}
264EXPORT_SYMBOL_GPL(watchdog_register_device);
265
266static void __watchdog_unregister_device(struct watchdog_device *wdd)
267{
268 if (wdd == NULL)
269 return;
270
271 if (wdd->ops->restart)
272 unregister_restart_handler(&wdd->restart_nb);
273
274 watchdog_dev_unregister(wdd);
275 ida_simple_remove(&watchdog_ida, wdd->id);
276}
277
278/**
279 * watchdog_unregister_device() - unregister a watchdog device
280 * @wdd: watchdog device to unregister
281 *
282 * Unregister a watchdog device that was previously successfully
283 * registered with watchdog_register_device().
284 */
285
286void watchdog_unregister_device(struct watchdog_device *wdd)
287{
288 mutex_lock(&wtd_deferred_reg_mutex);
289 if (wtd_deferred_reg_done)
290 __watchdog_unregister_device(wdd);
291 else
292 watchdog_deferred_registration_del(wdd);
293 mutex_unlock(&wtd_deferred_reg_mutex);
294}
295
296EXPORT_SYMBOL_GPL(watchdog_unregister_device);
297
298static void devm_watchdog_unregister_device(struct device *dev, void *res)
299{
300 watchdog_unregister_device(*(struct watchdog_device **)res);
301}
302
303/**
304 * devm_watchdog_register_device() - resource managed watchdog_register_device()
305 * @dev: device that is registering this watchdog device
306 * @wdd: watchdog device
307 *
308 * Managed watchdog_register_device(). For watchdog device registered by this
309 * function, watchdog_unregister_device() is automatically called on driver
310 * detach. See watchdog_register_device() for more information.
311 */
312int devm_watchdog_register_device(struct device *dev,
313 struct watchdog_device *wdd)
314{
315 struct watchdog_device **rcwdd;
316 int ret;
317
318 rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
319 GFP_KERNEL);
320 if (!rcwdd)
321 return -ENOMEM;
322
323 ret = watchdog_register_device(wdd);
324 if (!ret) {
325 *rcwdd = wdd;
326 devres_add(dev, rcwdd);
327 } else {
328 devres_free(rcwdd);
329 }
330
331 return ret;
332}
333EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
334
335static int __init watchdog_deferred_registration(void)
336{
337 mutex_lock(&wtd_deferred_reg_mutex);
338 wtd_deferred_reg_done = true;
339 while (!list_empty(&wtd_deferred_reg_list)) {
340 struct watchdog_device *wdd;
341
342 wdd = list_first_entry(&wtd_deferred_reg_list,
343 struct watchdog_device, deferred);
344 list_del(&wdd->deferred);
345 __watchdog_register_device(wdd);
346 }
347 mutex_unlock(&wtd_deferred_reg_mutex);
348 return 0;
349}
350
351static int __init watchdog_init(void)
352{
353 int err;
354
355 err = watchdog_dev_init();
356 if (err < 0)
357 return err;
358
359 watchdog_deferred_registration();
360 return 0;
361}
362
363static void __exit watchdog_exit(void)
364{
365 watchdog_dev_exit();
366 ida_destroy(&watchdog_ida);
367}
368
369subsys_initcall_sync(watchdog_init);
370module_exit(watchdog_exit);
371
372MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
373MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
374MODULE_DESCRIPTION("WatchDog Timer Driver Core");
375MODULE_LICENSE("GPL");