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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/*
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->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 * @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.
108 *
109 * A zero is returned on success and -EINVAL for failure.
110 */
111int watchdog_init_timeout(struct watchdog_device *wdd,
112 unsigned int timeout_parm, struct device *dev)
113{
114 unsigned int t = 0;
115 int ret = 0;
116
117 watchdog_check_min_max_timeout(wdd);
118
119 /* try to get the timeout module parameter first */
120 if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
121 wdd->timeout = timeout_parm;
122 return ret;
123 }
124 if (timeout_parm)
125 ret = -EINVAL;
126
127 /* try to get the timeout_sec property */
128 if (dev == NULL || dev->of_node == NULL)
129 return ret;
130 of_property_read_u32(dev->of_node, "timeout-sec", &t);
131 if (!watchdog_timeout_invalid(wdd, t) && t)
132 wdd->timeout = t;
133 else
134 ret = -EINVAL;
135
136 return ret;
137}
138EXPORT_SYMBOL_GPL(watchdog_init_timeout);
139
140static int watchdog_reboot_notifier(struct notifier_block *nb,
141 unsigned long code, void *data)
142{
143 struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
144 reboot_nb);
145
146 if (code == SYS_DOWN || code == SYS_HALT) {
147 if (watchdog_active(wdd)) {
148 int ret;
149
150 ret = wdd->ops->stop(wdd);
151 if (ret)
152 return NOTIFY_BAD;
153 }
154 }
155
156 return NOTIFY_DONE;
157}
158
159static int watchdog_restart_notifier(struct notifier_block *nb,
160 unsigned long action, void *data)
161{
162 struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
163 restart_nb);
164
165 int ret;
166
167 ret = wdd->ops->restart(wdd, action, data);
168 if (ret)
169 return NOTIFY_BAD;
170
171 return NOTIFY_DONE;
172}
173
174/**
175 * watchdog_set_restart_priority - Change priority of restart handler
176 * @wdd: watchdog device
177 * @priority: priority of the restart handler, should follow these guidelines:
178 * 0: use watchdog's restart function as last resort, has limited restart
179 * capabilies
180 * 128: default restart handler, use if no other handler is expected to be
181 * available and/or if restart is sufficient to restart the entire system
182 * 255: preempt all other handlers
183 *
184 * If a wdd->ops->restart function is provided when watchdog_register_device is
185 * called, it will be registered as a restart handler with the priority given
186 * here.
187 */
188void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
189{
190 wdd->restart_nb.priority = priority;
191}
192EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
193
194static int __watchdog_register_device(struct watchdog_device *wdd)
195{
196 int ret, id = -1;
197
198 if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
199 return -EINVAL;
200
201 /* Mandatory operations need to be supported */
202 if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
203 return -EINVAL;
204
205 watchdog_check_min_max_timeout(wdd);
206
207 /*
208 * Note: now that all watchdog_device data has been verified, we
209 * will not check this anymore in other functions. If data gets
210 * corrupted in a later stage then we expect a kernel panic!
211 */
212
213 /* Use alias for watchdog id if possible */
214 if (wdd->parent) {
215 ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
216 if (ret >= 0)
217 id = ida_simple_get(&watchdog_ida, ret,
218 ret + 1, GFP_KERNEL);
219 }
220
221 if (id < 0)
222 id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
223
224 if (id < 0)
225 return id;
226 wdd->id = id;
227
228 ret = watchdog_dev_register(wdd);
229 if (ret) {
230 ida_simple_remove(&watchdog_ida, id);
231 if (!(id == 0 && ret == -EBUSY))
232 return ret;
233
234 /* Retry in case a legacy watchdog module exists */
235 id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
236 if (id < 0)
237 return id;
238 wdd->id = id;
239
240 ret = watchdog_dev_register(wdd);
241 if (ret) {
242 ida_simple_remove(&watchdog_ida, id);
243 return ret;
244 }
245 }
246
247 if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
248 wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
249
250 ret = register_reboot_notifier(&wdd->reboot_nb);
251 if (ret) {
252 pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
253 wdd->id, ret);
254 watchdog_dev_unregister(wdd);
255 ida_simple_remove(&watchdog_ida, wdd->id);
256 return ret;
257 }
258 }
259
260 if (wdd->ops->restart) {
261 wdd->restart_nb.notifier_call = watchdog_restart_notifier;
262
263 ret = register_restart_handler(&wdd->restart_nb);
264 if (ret)
265 pr_warn("watchog%d: Cannot register restart handler (%d)\n",
266 wdd->id, ret);
267 }
268
269 return 0;
270}
271
272/**
273 * watchdog_register_device() - register a watchdog device
274 * @wdd: watchdog device
275 *
276 * Register a watchdog device with the kernel so that the
277 * watchdog timer can be accessed from userspace.
278 *
279 * A zero is returned on success and a negative errno code for
280 * failure.
281 */
282
283int watchdog_register_device(struct watchdog_device *wdd)
284{
285 int ret;
286
287 mutex_lock(&wtd_deferred_reg_mutex);
288 if (wtd_deferred_reg_done)
289 ret = __watchdog_register_device(wdd);
290 else
291 ret = watchdog_deferred_registration_add(wdd);
292 mutex_unlock(&wtd_deferred_reg_mutex);
293 return ret;
294}
295EXPORT_SYMBOL_GPL(watchdog_register_device);
296
297static void __watchdog_unregister_device(struct watchdog_device *wdd)
298{
299 if (wdd == NULL)
300 return;
301
302 if (wdd->ops->restart)
303 unregister_restart_handler(&wdd->restart_nb);
304
305 if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
306 unregister_reboot_notifier(&wdd->reboot_nb);
307
308 watchdog_dev_unregister(wdd);
309 ida_simple_remove(&watchdog_ida, wdd->id);
310}
311
312/**
313 * watchdog_unregister_device() - unregister a watchdog device
314 * @wdd: watchdog device to unregister
315 *
316 * Unregister a watchdog device that was previously successfully
317 * registered with watchdog_register_device().
318 */
319
320void watchdog_unregister_device(struct watchdog_device *wdd)
321{
322 mutex_lock(&wtd_deferred_reg_mutex);
323 if (wtd_deferred_reg_done)
324 __watchdog_unregister_device(wdd);
325 else
326 watchdog_deferred_registration_del(wdd);
327 mutex_unlock(&wtd_deferred_reg_mutex);
328}
329
330EXPORT_SYMBOL_GPL(watchdog_unregister_device);
331
332static int __init watchdog_deferred_registration(void)
333{
334 mutex_lock(&wtd_deferred_reg_mutex);
335 wtd_deferred_reg_done = true;
336 while (!list_empty(&wtd_deferred_reg_list)) {
337 struct watchdog_device *wdd;
338
339 wdd = list_first_entry(&wtd_deferred_reg_list,
340 struct watchdog_device, deferred);
341 list_del(&wdd->deferred);
342 __watchdog_register_device(wdd);
343 }
344 mutex_unlock(&wtd_deferred_reg_mutex);
345 return 0;
346}
347
348static int __init watchdog_init(void)
349{
350 int err;
351
352 err = watchdog_dev_init();
353 if (err < 0)
354 return err;
355
356 watchdog_deferred_registration();
357 return 0;
358}
359
360static void __exit watchdog_exit(void)
361{
362 watchdog_dev_exit();
363 ida_destroy(&watchdog_ida);
364}
365
366subsys_initcall_sync(watchdog_init);
367module_exit(watchdog_exit);
368
369MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
370MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
371MODULE_DESCRIPTION("WatchDog Timer Driver Core");
372MODULE_LICENSE("GPL");