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