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33#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34
35#include <linux/module.h>
36#include <linux/types.h>
37#include <linux/errno.h>
38#include <linux/kernel.h>
39#include <linux/fs.h>
40#include <linux/watchdog.h>
41#include <linux/miscdevice.h>
42#include <linux/init.h>
43#include <linux/uaccess.h>
44
45#include "watchdog_core.h"
46
47
48static dev_t watchdog_devt;
49
50static struct watchdog_device *old_wdd;
51
52
53
54
55
56
57
58
59
60
61
62static int watchdog_ping(struct watchdog_device *wddev)
63{
64 int err = 0;
65
66 mutex_lock(&wddev->lock);
67
68 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
69 err = -ENODEV;
70 goto out_ping;
71 }
72
73 if (!watchdog_active(wddev))
74 goto out_ping;
75
76 if (wddev->ops->ping)
77 err = wddev->ops->ping(wddev);
78 else
79 err = wddev->ops->start(wddev);
80
81out_ping:
82 mutex_unlock(&wddev->lock);
83 return err;
84}
85
86
87
88
89
90
91
92
93
94
95static int watchdog_start(struct watchdog_device *wddev)
96{
97 int err = 0;
98
99 mutex_lock(&wddev->lock);
100
101 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
102 err = -ENODEV;
103 goto out_start;
104 }
105
106 if (watchdog_active(wddev))
107 goto out_start;
108
109 err = wddev->ops->start(wddev);
110 if (err == 0)
111 set_bit(WDOG_ACTIVE, &wddev->status);
112
113out_start:
114 mutex_unlock(&wddev->lock);
115 return err;
116}
117
118
119
120
121
122
123
124
125
126
127
128static int watchdog_stop(struct watchdog_device *wddev)
129{
130 int err = 0;
131
132 mutex_lock(&wddev->lock);
133
134 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
135 err = -ENODEV;
136 goto out_stop;
137 }
138
139 if (!watchdog_active(wddev))
140 goto out_stop;
141
142 if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) {
143 dev_info(wddev->dev, "nowayout prevents watchdog being stopped!\n");
144 err = -EBUSY;
145 goto out_stop;
146 }
147
148 err = wddev->ops->stop(wddev);
149 if (err == 0)
150 clear_bit(WDOG_ACTIVE, &wddev->status);
151
152out_stop:
153 mutex_unlock(&wddev->lock);
154 return err;
155}
156
157
158
159
160
161
162
163
164
165static int watchdog_get_status(struct watchdog_device *wddev,
166 unsigned int *status)
167{
168 int err = 0;
169
170 *status = 0;
171 if (!wddev->ops->status)
172 return -EOPNOTSUPP;
173
174 mutex_lock(&wddev->lock);
175
176 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
177 err = -ENODEV;
178 goto out_status;
179 }
180
181 *status = wddev->ops->status(wddev);
182
183out_status:
184 mutex_unlock(&wddev->lock);
185 return err;
186}
187
188
189
190
191
192
193
194static int watchdog_set_timeout(struct watchdog_device *wddev,
195 unsigned int timeout)
196{
197 int err;
198
199 if ((wddev->ops->set_timeout == NULL) ||
200 !(wddev->info->options & WDIOF_SETTIMEOUT))
201 return -EOPNOTSUPP;
202
203 if (watchdog_timeout_invalid(wddev, timeout))
204 return -EINVAL;
205
206 mutex_lock(&wddev->lock);
207
208 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
209 err = -ENODEV;
210 goto out_timeout;
211 }
212
213 err = wddev->ops->set_timeout(wddev, timeout);
214
215out_timeout:
216 mutex_unlock(&wddev->lock);
217 return err;
218}
219
220
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225
226
227
228static int watchdog_get_timeleft(struct watchdog_device *wddev,
229 unsigned int *timeleft)
230{
231 int err = 0;
232
233 *timeleft = 0;
234 if (!wddev->ops->get_timeleft)
235 return -EOPNOTSUPP;
236
237 mutex_lock(&wddev->lock);
238
239 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
240 err = -ENODEV;
241 goto out_timeleft;
242 }
243
244 *timeleft = wddev->ops->get_timeleft(wddev);
245
246out_timeleft:
247 mutex_unlock(&wddev->lock);
248 return err;
249}
250
251
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253
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255
256
257
258static int watchdog_ioctl_op(struct watchdog_device *wddev, unsigned int cmd,
259 unsigned long arg)
260{
261 int err;
262
263 if (!wddev->ops->ioctl)
264 return -ENOIOCTLCMD;
265
266 mutex_lock(&wddev->lock);
267
268 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
269 err = -ENODEV;
270 goto out_ioctl;
271 }
272
273 err = wddev->ops->ioctl(wddev, cmd, arg);
274
275out_ioctl:
276 mutex_unlock(&wddev->lock);
277 return err;
278}
279
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290
291
292static ssize_t watchdog_write(struct file *file, const char __user *data,
293 size_t len, loff_t *ppos)
294{
295 struct watchdog_device *wdd = file->private_data;
296 size_t i;
297 char c;
298
299 if (len == 0)
300 return 0;
301
302
303
304
305
306 clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
307
308
309 for (i = 0; i != len; i++) {
310 if (get_user(c, data + i))
311 return -EFAULT;
312 if (c == 'V')
313 set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
314 }
315
316
317 watchdog_ping(wdd);
318
319 return len;
320}
321
322
323
324
325
326
327
328
329
330
331
332static long watchdog_ioctl(struct file *file, unsigned int cmd,
333 unsigned long arg)
334{
335 struct watchdog_device *wdd = file->private_data;
336 void __user *argp = (void __user *)arg;
337 int __user *p = argp;
338 unsigned int val;
339 int err;
340
341 err = watchdog_ioctl_op(wdd, cmd, arg);
342 if (err != -ENOIOCTLCMD)
343 return err;
344
345 switch (cmd) {
346 case WDIOC_GETSUPPORT:
347 return copy_to_user(argp, wdd->info,
348 sizeof(struct watchdog_info)) ? -EFAULT : 0;
349 case WDIOC_GETSTATUS:
350 err = watchdog_get_status(wdd, &val);
351 if (err == -ENODEV)
352 return err;
353 return put_user(val, p);
354 case WDIOC_GETBOOTSTATUS:
355 return put_user(wdd->bootstatus, p);
356 case WDIOC_SETOPTIONS:
357 if (get_user(val, p))
358 return -EFAULT;
359 if (val & WDIOS_DISABLECARD) {
360 err = watchdog_stop(wdd);
361 if (err < 0)
362 return err;
363 }
364 if (val & WDIOS_ENABLECARD) {
365 err = watchdog_start(wdd);
366 if (err < 0)
367 return err;
368 }
369 return 0;
370 case WDIOC_KEEPALIVE:
371 if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
372 return -EOPNOTSUPP;
373 watchdog_ping(wdd);
374 return 0;
375 case WDIOC_SETTIMEOUT:
376 if (get_user(val, p))
377 return -EFAULT;
378 err = watchdog_set_timeout(wdd, val);
379 if (err < 0)
380 return err;
381
382
383
384 watchdog_ping(wdd);
385
386 case WDIOC_GETTIMEOUT:
387
388 if (wdd->timeout == 0)
389 return -EOPNOTSUPP;
390 return put_user(wdd->timeout, p);
391 case WDIOC_GETTIMELEFT:
392 err = watchdog_get_timeleft(wdd, &val);
393 if (err)
394 return err;
395 return put_user(val, p);
396 default:
397 return -ENOTTY;
398 }
399}
400
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404
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408
409
410
411static int watchdog_open(struct inode *inode, struct file *file)
412{
413 int err = -EBUSY;
414 struct watchdog_device *wdd;
415
416
417 if (imajor(inode) == MISC_MAJOR)
418 wdd = old_wdd;
419 else
420 wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);
421
422
423 if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
424 return -EBUSY;
425
426
427
428
429
430 if (!try_module_get(wdd->ops->owner))
431 goto out;
432
433 err = watchdog_start(wdd);
434 if (err < 0)
435 goto out_mod;
436
437 file->private_data = wdd;
438
439 if (wdd->ops->ref)
440 wdd->ops->ref(wdd);
441
442
443 return nonseekable_open(inode, file);
444
445out_mod:
446 module_put(wdd->ops->owner);
447out:
448 clear_bit(WDOG_DEV_OPEN, &wdd->status);
449 return err;
450}
451
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459
460
461
462static int watchdog_release(struct inode *inode, struct file *file)
463{
464 struct watchdog_device *wdd = file->private_data;
465 int err = -EBUSY;
466
467
468
469
470
471
472 if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
473 !(wdd->info->options & WDIOF_MAGICCLOSE))
474 err = watchdog_stop(wdd);
475
476
477 if (err < 0) {
478 mutex_lock(&wdd->lock);
479 if (!test_bit(WDOG_UNREGISTERED, &wdd->status))
480 dev_crit(wdd->dev, "watchdog did not stop!\n");
481 mutex_unlock(&wdd->lock);
482 watchdog_ping(wdd);
483 }
484
485
486 module_put(wdd->ops->owner);
487
488
489 clear_bit(WDOG_DEV_OPEN, &wdd->status);
490
491
492 if (wdd->ops->unref)
493 wdd->ops->unref(wdd);
494
495 return 0;
496}
497
498static const struct file_operations watchdog_fops = {
499 .owner = THIS_MODULE,
500 .write = watchdog_write,
501 .unlocked_ioctl = watchdog_ioctl,
502 .open = watchdog_open,
503 .release = watchdog_release,
504};
505
506static struct miscdevice watchdog_miscdev = {
507 .minor = WATCHDOG_MINOR,
508 .name = "watchdog",
509 .fops = &watchdog_fops,
510};
511
512
513
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515
516
517
518
519
520
521int watchdog_dev_register(struct watchdog_device *watchdog)
522{
523 int err, devno;
524
525 if (watchdog->id == 0) {
526 old_wdd = watchdog;
527 watchdog_miscdev.parent = watchdog->parent;
528 err = misc_register(&watchdog_miscdev);
529 if (err != 0) {
530 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
531 watchdog->info->identity, WATCHDOG_MINOR, err);
532 if (err == -EBUSY)
533 pr_err("%s: a legacy watchdog module is probably present.\n",
534 watchdog->info->identity);
535 old_wdd = NULL;
536 return err;
537 }
538 }
539
540
541 devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
542 cdev_init(&watchdog->cdev, &watchdog_fops);
543 watchdog->cdev.owner = watchdog->ops->owner;
544
545
546 err = cdev_add(&watchdog->cdev, devno, 1);
547 if (err) {
548 pr_err("watchdog%d unable to add device %d:%d\n",
549 watchdog->id, MAJOR(watchdog_devt), watchdog->id);
550 if (watchdog->id == 0) {
551 misc_deregister(&watchdog_miscdev);
552 old_wdd = NULL;
553 }
554 }
555 return err;
556}
557
558
559
560
561
562
563
564
565int watchdog_dev_unregister(struct watchdog_device *watchdog)
566{
567 mutex_lock(&watchdog->lock);
568 set_bit(WDOG_UNREGISTERED, &watchdog->status);
569 mutex_unlock(&watchdog->lock);
570
571 cdev_del(&watchdog->cdev);
572 if (watchdog->id == 0) {
573 misc_deregister(&watchdog_miscdev);
574 old_wdd = NULL;
575 }
576 return 0;
577}
578
579
580
581
582
583
584
585int __init watchdog_dev_init(void)
586{
587 int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
588 if (err < 0)
589 pr_err("watchdog: unable to allocate char dev region\n");
590 return err;
591}
592
593
594
595
596
597
598
599void __exit watchdog_dev_exit(void)
600{
601 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
602}
603