Commit | Line | Data |
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43316044 WVS |
1 | /* |
2 | * watchdog_dev.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 | * | |
10 | * This source code is part of the generic code that can be used | |
11 | * by all the watchdog timer drivers. | |
12 | * | |
13 | * This part of the generic code takes care of the following | |
14 | * misc device: /dev/watchdog. | |
15 | * | |
16 | * Based on source code of the following authors: | |
17 | * Matt Domsch <Matt_Domsch@dell.com>, | |
18 | * Rob Radez <rob@osinvestor.com>, | |
19 | * Rusty Lynch <rusty@linux.co.intel.com> | |
20 | * Satyam Sharma <satyam@infradead.org> | |
21 | * Randy Dunlap <randy.dunlap@oracle.com> | |
22 | * | |
23 | * This program is free software; you can redistribute it and/or | |
24 | * modify it under the terms of the GNU General Public License | |
25 | * as published by the Free Software Foundation; either version | |
26 | * 2 of the License, or (at your option) any later version. | |
27 | * | |
28 | * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. | |
29 | * admit liability nor provide warranty for any of this software. | |
30 | * This material is provided "AS-IS" and at no charge. | |
31 | */ | |
32 | ||
33 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
34 | ||
35 | #include <linux/module.h> /* For module stuff/... */ | |
36 | #include <linux/types.h> /* For standard types (like size_t) */ | |
37 | #include <linux/errno.h> /* For the -ENODEV/... values */ | |
38 | #include <linux/kernel.h> /* For printk/panic/... */ | |
39 | #include <linux/fs.h> /* For file operations */ | |
40 | #include <linux/watchdog.h> /* For watchdog specific items */ | |
41 | #include <linux/miscdevice.h> /* For handling misc devices */ | |
42 | #include <linux/init.h> /* For __init/__exit/... */ | |
43 | #include <linux/uaccess.h> /* For copy_to_user/put_user/... */ | |
44 | ||
6cfb5aa8 | 45 | #include "watchdog_core.h" |
09a46e73 | 46 | |
45f5fed3 AC |
47 | /* the dev_t structure to store the dynamically allocated watchdog devices */ |
48 | static dev_t watchdog_devt; | |
43316044 | 49 | /* the watchdog device behind /dev/watchdog */ |
45f5fed3 | 50 | static struct watchdog_device *old_wdd; |
43316044 WVS |
51 | |
52 | /* | |
53 | * watchdog_ping: ping the watchdog. | |
54 | * @wddev: the watchdog device to ping | |
55 | * | |
56 | * If the watchdog has no own ping operation then it needs to be | |
57 | * restarted via the start operation. This wrapper function does | |
58 | * exactly that. | |
234445b4 | 59 | * We only ping when the watchdog device is running. |
43316044 WVS |
60 | */ |
61 | ||
62 | static int watchdog_ping(struct watchdog_device *wddev) | |
63 | { | |
7a879824 HG |
64 | int err = 0; |
65 | ||
f4e9c82f HG |
66 | mutex_lock(&wddev->lock); |
67 | ||
7a879824 HG |
68 | if (!watchdog_active(wddev)) |
69 | goto out_ping; | |
70 | ||
71 | if (wddev->ops->ping) | |
72 | err = wddev->ops->ping(wddev); /* ping the watchdog */ | |
73 | else | |
74 | err = wddev->ops->start(wddev); /* restart watchdog */ | |
75 | ||
76 | out_ping: | |
f4e9c82f | 77 | mutex_unlock(&wddev->lock); |
7a879824 | 78 | return err; |
234445b4 WVS |
79 | } |
80 | ||
81 | /* | |
82 | * watchdog_start: wrapper to start the watchdog. | |
83 | * @wddev: the watchdog device to start | |
84 | * | |
85 | * Start the watchdog if it is not active and mark it active. | |
86 | * This function returns zero on success or a negative errno code for | |
87 | * failure. | |
88 | */ | |
89 | ||
90 | static int watchdog_start(struct watchdog_device *wddev) | |
91 | { | |
7a879824 | 92 | int err = 0; |
234445b4 | 93 | |
f4e9c82f HG |
94 | mutex_lock(&wddev->lock); |
95 | ||
7a879824 HG |
96 | if (watchdog_active(wddev)) |
97 | goto out_start; | |
234445b4 | 98 | |
7a879824 HG |
99 | err = wddev->ops->start(wddev); |
100 | if (err == 0) | |
cb7efc02 | 101 | set_bit(WDOG_ACTIVE, &wddev->status); |
7a879824 HG |
102 | |
103 | out_start: | |
f4e9c82f | 104 | mutex_unlock(&wddev->lock); |
7a879824 | 105 | return err; |
234445b4 WVS |
106 | } |
107 | ||
108 | /* | |
109 | * watchdog_stop: wrapper to stop the watchdog. | |
110 | * @wddev: the watchdog device to stop | |
111 | * | |
112 | * Stop the watchdog if it is still active and unmark it active. | |
113 | * This function returns zero on success or a negative errno code for | |
114 | * failure. | |
7e192b9c | 115 | * If the 'nowayout' feature was set, the watchdog cannot be stopped. |
234445b4 WVS |
116 | */ |
117 | ||
118 | static int watchdog_stop(struct watchdog_device *wddev) | |
119 | { | |
7a879824 HG |
120 | int err = 0; |
121 | ||
f4e9c82f HG |
122 | mutex_lock(&wddev->lock); |
123 | ||
7a879824 HG |
124 | if (!watchdog_active(wddev)) |
125 | goto out_stop; | |
7e192b9c | 126 | |
cb7efc02 | 127 | if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) { |
3dfd6218 | 128 | dev_info(wddev->dev, "nowayout prevents watchdog being stopped!\n"); |
7a879824 HG |
129 | err = -EBUSY; |
130 | goto out_stop; | |
7e192b9c | 131 | } |
234445b4 | 132 | |
7a879824 HG |
133 | err = wddev->ops->stop(wddev); |
134 | if (err == 0) | |
cb7efc02 | 135 | clear_bit(WDOG_ACTIVE, &wddev->status); |
7a879824 HG |
136 | |
137 | out_stop: | |
f4e9c82f | 138 | mutex_unlock(&wddev->lock); |
7a879824 HG |
139 | return err; |
140 | } | |
141 | ||
142 | /* | |
143 | * watchdog_get_status: wrapper to get the watchdog status | |
144 | * @wddev: the watchdog device to get the status from | |
145 | * @status: the status of the watchdog device | |
146 | * | |
147 | * Get the watchdog's status flags. | |
148 | */ | |
149 | ||
150 | static int watchdog_get_status(struct watchdog_device *wddev, | |
151 | unsigned int *status) | |
152 | { | |
153 | int err = 0; | |
154 | ||
155 | *status = 0; | |
156 | if (!wddev->ops->status) | |
157 | return -EOPNOTSUPP; | |
158 | ||
f4e9c82f HG |
159 | mutex_lock(&wddev->lock); |
160 | ||
7a879824 HG |
161 | *status = wddev->ops->status(wddev); |
162 | ||
f4e9c82f | 163 | mutex_unlock(&wddev->lock); |
7a879824 HG |
164 | return err; |
165 | } | |
166 | ||
167 | /* | |
168 | * watchdog_set_timeout: set the watchdog timer timeout | |
169 | * @wddev: the watchdog device to set the timeout for | |
170 | * @timeout: timeout to set in seconds | |
171 | */ | |
172 | ||
173 | static int watchdog_set_timeout(struct watchdog_device *wddev, | |
174 | unsigned int timeout) | |
175 | { | |
176 | int err; | |
177 | ||
178 | if ((wddev->ops->set_timeout == NULL) || | |
179 | !(wddev->info->options & WDIOF_SETTIMEOUT)) | |
180 | return -EOPNOTSUPP; | |
181 | ||
182 | if ((wddev->max_timeout != 0) && | |
183 | (timeout < wddev->min_timeout || timeout > wddev->max_timeout)) | |
184 | return -EINVAL; | |
185 | ||
f4e9c82f HG |
186 | mutex_lock(&wddev->lock); |
187 | ||
7a879824 HG |
188 | err = wddev->ops->set_timeout(wddev, timeout); |
189 | ||
f4e9c82f | 190 | mutex_unlock(&wddev->lock); |
7a879824 HG |
191 | return err; |
192 | } | |
193 | ||
194 | /* | |
195 | * watchdog_get_timeleft: wrapper to get the time left before a reboot | |
196 | * @wddev: the watchdog device to get the remaining time from | |
197 | * @timeleft: the time that's left | |
198 | * | |
199 | * Get the time before a watchdog will reboot (if not pinged). | |
200 | */ | |
201 | ||
202 | static int watchdog_get_timeleft(struct watchdog_device *wddev, | |
203 | unsigned int *timeleft) | |
204 | { | |
205 | int err = 0; | |
206 | ||
207 | *timeleft = 0; | |
208 | if (!wddev->ops->get_timeleft) | |
209 | return -EOPNOTSUPP; | |
210 | ||
f4e9c82f HG |
211 | mutex_lock(&wddev->lock); |
212 | ||
7a879824 HG |
213 | *timeleft = wddev->ops->get_timeleft(wddev); |
214 | ||
f4e9c82f | 215 | mutex_unlock(&wddev->lock); |
7a879824 HG |
216 | return err; |
217 | } | |
218 | ||
219 | /* | |
220 | * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined | |
221 | * @wddev: the watchdog device to do the ioctl on | |
222 | * @cmd: watchdog command | |
223 | * @arg: argument pointer | |
224 | */ | |
225 | ||
226 | static int watchdog_ioctl_op(struct watchdog_device *wddev, unsigned int cmd, | |
227 | unsigned long arg) | |
228 | { | |
229 | int err; | |
230 | ||
231 | if (!wddev->ops->ioctl) | |
232 | return -ENOIOCTLCMD; | |
233 | ||
f4e9c82f HG |
234 | mutex_lock(&wddev->lock); |
235 | ||
7a879824 HG |
236 | err = wddev->ops->ioctl(wddev, cmd, arg); |
237 | ||
f4e9c82f | 238 | mutex_unlock(&wddev->lock); |
7a879824 | 239 | return err; |
43316044 WVS |
240 | } |
241 | ||
242 | /* | |
243 | * watchdog_write: writes to the watchdog. | |
244 | * @file: file from VFS | |
245 | * @data: user address of data | |
246 | * @len: length of data | |
247 | * @ppos: pointer to the file offset | |
248 | * | |
249 | * A write to a watchdog device is defined as a keepalive ping. | |
017cf080 | 250 | * Writing the magic 'V' sequence allows the next close to turn |
7e192b9c | 251 | * off the watchdog (if 'nowayout' is not set). |
43316044 WVS |
252 | */ |
253 | ||
254 | static ssize_t watchdog_write(struct file *file, const char __user *data, | |
255 | size_t len, loff_t *ppos) | |
256 | { | |
45f5fed3 | 257 | struct watchdog_device *wdd = file->private_data; |
43316044 WVS |
258 | size_t i; |
259 | char c; | |
260 | ||
261 | if (len == 0) | |
262 | return 0; | |
263 | ||
017cf080 WVS |
264 | /* |
265 | * Note: just in case someone wrote the magic character | |
266 | * five months ago... | |
267 | */ | |
268 | clear_bit(WDOG_ALLOW_RELEASE, &wdd->status); | |
269 | ||
270 | /* scan to see whether or not we got the magic character */ | |
43316044 WVS |
271 | for (i = 0; i != len; i++) { |
272 | if (get_user(c, data + i)) | |
273 | return -EFAULT; | |
017cf080 WVS |
274 | if (c == 'V') |
275 | set_bit(WDOG_ALLOW_RELEASE, &wdd->status); | |
43316044 WVS |
276 | } |
277 | ||
278 | /* someone wrote to us, so we send the watchdog a keepalive ping */ | |
279 | watchdog_ping(wdd); | |
280 | ||
281 | return len; | |
282 | } | |
283 | ||
2fa03560 WVS |
284 | /* |
285 | * watchdog_ioctl: handle the different ioctl's for the watchdog device. | |
286 | * @file: file handle to the device | |
287 | * @cmd: watchdog command | |
288 | * @arg: argument pointer | |
289 | * | |
290 | * The watchdog API defines a common set of functions for all watchdogs | |
291 | * according to their available features. | |
292 | */ | |
293 | ||
294 | static long watchdog_ioctl(struct file *file, unsigned int cmd, | |
295 | unsigned long arg) | |
296 | { | |
45f5fed3 | 297 | struct watchdog_device *wdd = file->private_data; |
2fa03560 WVS |
298 | void __user *argp = (void __user *)arg; |
299 | int __user *p = argp; | |
300 | unsigned int val; | |
234445b4 | 301 | int err; |
2fa03560 | 302 | |
7a879824 HG |
303 | err = watchdog_ioctl_op(wdd, cmd, arg); |
304 | if (err != -ENOIOCTLCMD) | |
305 | return err; | |
78d88fc0 | 306 | |
2fa03560 WVS |
307 | switch (cmd) { |
308 | case WDIOC_GETSUPPORT: | |
309 | return copy_to_user(argp, wdd->info, | |
310 | sizeof(struct watchdog_info)) ? -EFAULT : 0; | |
311 | case WDIOC_GETSTATUS: | |
7a879824 HG |
312 | err = watchdog_get_status(wdd, &val); |
313 | if (err) | |
314 | return err; | |
2fa03560 WVS |
315 | return put_user(val, p); |
316 | case WDIOC_GETBOOTSTATUS: | |
317 | return put_user(wdd->bootstatus, p); | |
234445b4 WVS |
318 | case WDIOC_SETOPTIONS: |
319 | if (get_user(val, p)) | |
320 | return -EFAULT; | |
321 | if (val & WDIOS_DISABLECARD) { | |
322 | err = watchdog_stop(wdd); | |
323 | if (err < 0) | |
324 | return err; | |
325 | } | |
326 | if (val & WDIOS_ENABLECARD) { | |
327 | err = watchdog_start(wdd); | |
328 | if (err < 0) | |
329 | return err; | |
330 | } | |
331 | return 0; | |
c2dc00e4 WVS |
332 | case WDIOC_KEEPALIVE: |
333 | if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) | |
334 | return -EOPNOTSUPP; | |
335 | watchdog_ping(wdd); | |
336 | return 0; | |
014d694e | 337 | case WDIOC_SETTIMEOUT: |
014d694e WVS |
338 | if (get_user(val, p)) |
339 | return -EFAULT; | |
7a879824 | 340 | err = watchdog_set_timeout(wdd, val); |
014d694e WVS |
341 | if (err < 0) |
342 | return err; | |
014d694e WVS |
343 | /* If the watchdog is active then we send a keepalive ping |
344 | * to make sure that the watchdog keep's running (and if | |
345 | * possible that it takes the new timeout) */ | |
346 | watchdog_ping(wdd); | |
347 | /* Fall */ | |
348 | case WDIOC_GETTIMEOUT: | |
349 | /* timeout == 0 means that we don't know the timeout */ | |
350 | if (wdd->timeout == 0) | |
351 | return -EOPNOTSUPP; | |
352 | return put_user(wdd->timeout, p); | |
fd7b673c | 353 | case WDIOC_GETTIMELEFT: |
7a879824 HG |
354 | err = watchdog_get_timeleft(wdd, &val); |
355 | if (err) | |
356 | return err; | |
357 | return put_user(val, p); | |
2fa03560 WVS |
358 | default: |
359 | return -ENOTTY; | |
360 | } | |
361 | } | |
362 | ||
43316044 | 363 | /* |
45f5fed3 | 364 | * watchdog_open: open the /dev/watchdog* devices. |
43316044 WVS |
365 | * @inode: inode of device |
366 | * @file: file handle to device | |
367 | * | |
45f5fed3 | 368 | * When the /dev/watchdog* device gets opened, we start the watchdog. |
43316044 WVS |
369 | * Watch out: the /dev/watchdog device is single open, so we make sure |
370 | * it can only be opened once. | |
371 | */ | |
372 | ||
373 | static int watchdog_open(struct inode *inode, struct file *file) | |
374 | { | |
375 | int err = -EBUSY; | |
45f5fed3 AC |
376 | struct watchdog_device *wdd; |
377 | ||
378 | /* Get the corresponding watchdog device */ | |
379 | if (imajor(inode) == MISC_MAJOR) | |
380 | wdd = old_wdd; | |
381 | else | |
382 | wdd = container_of(inode->i_cdev, struct watchdog_device, cdev); | |
43316044 WVS |
383 | |
384 | /* the watchdog is single open! */ | |
385 | if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status)) | |
386 | return -EBUSY; | |
387 | ||
388 | /* | |
389 | * If the /dev/watchdog device is open, we don't want the module | |
390 | * to be unloaded. | |
391 | */ | |
392 | if (!try_module_get(wdd->ops->owner)) | |
393 | goto out; | |
394 | ||
234445b4 | 395 | err = watchdog_start(wdd); |
43316044 WVS |
396 | if (err < 0) |
397 | goto out_mod; | |
398 | ||
45f5fed3 AC |
399 | file->private_data = wdd; |
400 | ||
43316044 WVS |
401 | /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ |
402 | return nonseekable_open(inode, file); | |
403 | ||
404 | out_mod: | |
405 | module_put(wdd->ops->owner); | |
406 | out: | |
407 | clear_bit(WDOG_DEV_OPEN, &wdd->status); | |
408 | return err; | |
409 | } | |
410 | ||
411 | /* | |
45f5fed3 AC |
412 | * watchdog_release: release the watchdog device. |
413 | * @inode: inode of device | |
414 | * @file: file handle to device | |
43316044 | 415 | * |
017cf080 | 416 | * This is the code for when /dev/watchdog gets closed. We will only |
7e192b9c WVS |
417 | * stop the watchdog when we have received the magic char (and nowayout |
418 | * was not set), else the watchdog will keep running. | |
43316044 WVS |
419 | */ |
420 | ||
421 | static int watchdog_release(struct inode *inode, struct file *file) | |
422 | { | |
45f5fed3 | 423 | struct watchdog_device *wdd = file->private_data; |
017cf080 WVS |
424 | int err = -EBUSY; |
425 | ||
426 | /* | |
427 | * We only stop the watchdog if we received the magic character | |
7e192b9c WVS |
428 | * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then |
429 | * watchdog_stop will fail. | |
017cf080 WVS |
430 | */ |
431 | if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) || | |
432 | !(wdd->info->options & WDIOF_MAGICCLOSE)) | |
433 | err = watchdog_stop(wdd); | |
43316044 | 434 | |
017cf080 | 435 | /* If the watchdog was not stopped, send a keepalive ping */ |
234445b4 | 436 | if (err < 0) { |
3dfd6218 | 437 | dev_crit(wdd->dev, "watchdog did not stop!\n"); |
43316044 WVS |
438 | watchdog_ping(wdd); |
439 | } | |
440 | ||
441 | /* Allow the owner module to be unloaded again */ | |
442 | module_put(wdd->ops->owner); | |
443 | ||
444 | /* make sure that /dev/watchdog can be re-opened */ | |
445 | clear_bit(WDOG_DEV_OPEN, &wdd->status); | |
446 | ||
447 | return 0; | |
448 | } | |
449 | ||
450 | static const struct file_operations watchdog_fops = { | |
451 | .owner = THIS_MODULE, | |
452 | .write = watchdog_write, | |
2fa03560 | 453 | .unlocked_ioctl = watchdog_ioctl, |
43316044 WVS |
454 | .open = watchdog_open, |
455 | .release = watchdog_release, | |
456 | }; | |
457 | ||
458 | static struct miscdevice watchdog_miscdev = { | |
459 | .minor = WATCHDOG_MINOR, | |
460 | .name = "watchdog", | |
461 | .fops = &watchdog_fops, | |
462 | }; | |
463 | ||
464 | /* | |
45f5fed3 | 465 | * watchdog_dev_register: register a watchdog device |
43316044 WVS |
466 | * @watchdog: watchdog device |
467 | * | |
45f5fed3 AC |
468 | * Register a watchdog device including handling the legacy |
469 | * /dev/watchdog node. /dev/watchdog is actually a miscdevice and | |
470 | * thus we set it up like that. | |
43316044 WVS |
471 | */ |
472 | ||
473 | int watchdog_dev_register(struct watchdog_device *watchdog) | |
474 | { | |
45f5fed3 AC |
475 | int err, devno; |
476 | ||
477 | if (watchdog->id == 0) { | |
d6b469d9 | 478 | watchdog_miscdev.parent = watchdog->parent; |
45f5fed3 AC |
479 | err = misc_register(&watchdog_miscdev); |
480 | if (err != 0) { | |
481 | pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", | |
482 | watchdog->info->identity, WATCHDOG_MINOR, err); | |
483 | if (err == -EBUSY) | |
484 | pr_err("%s: a legacy watchdog module is probably present.\n", | |
485 | watchdog->info->identity); | |
486 | return err; | |
487 | } | |
488 | old_wdd = watchdog; | |
43316044 WVS |
489 | } |
490 | ||
45f5fed3 AC |
491 | /* Fill in the data structures */ |
492 | devno = MKDEV(MAJOR(watchdog_devt), watchdog->id); | |
493 | cdev_init(&watchdog->cdev, &watchdog_fops); | |
494 | watchdog->cdev.owner = watchdog->ops->owner; | |
495 | ||
496 | /* Add the device */ | |
497 | err = cdev_add(&watchdog->cdev, devno, 1); | |
498 | if (err) { | |
499 | pr_err("watchdog%d unable to add device %d:%d\n", | |
500 | watchdog->id, MAJOR(watchdog_devt), watchdog->id); | |
501 | if (watchdog->id == 0) { | |
502 | misc_deregister(&watchdog_miscdev); | |
503 | old_wdd = NULL; | |
504 | } | |
43316044 | 505 | } |
43316044 WVS |
506 | return err; |
507 | } | |
508 | ||
509 | /* | |
45f5fed3 | 510 | * watchdog_dev_unregister: unregister a watchdog device |
43316044 WVS |
511 | * @watchdog: watchdog device |
512 | * | |
45f5fed3 | 513 | * Unregister the watchdog and if needed the legacy /dev/watchdog device. |
43316044 WVS |
514 | */ |
515 | ||
516 | int watchdog_dev_unregister(struct watchdog_device *watchdog) | |
517 | { | |
45f5fed3 AC |
518 | cdev_del(&watchdog->cdev); |
519 | if (watchdog->id == 0) { | |
520 | misc_deregister(&watchdog_miscdev); | |
521 | old_wdd = NULL; | |
43316044 | 522 | } |
43316044 WVS |
523 | return 0; |
524 | } | |
45f5fed3 AC |
525 | |
526 | /* | |
527 | * watchdog_dev_init: init dev part of watchdog core | |
528 | * | |
529 | * Allocate a range of chardev nodes to use for watchdog devices | |
530 | */ | |
531 | ||
532 | int __init watchdog_dev_init(void) | |
533 | { | |
534 | int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog"); | |
535 | if (err < 0) | |
536 | pr_err("watchdog: unable to allocate char dev region\n"); | |
537 | return err; | |
538 | } | |
539 | ||
540 | /* | |
541 | * watchdog_dev_exit: exit dev part of watchdog core | |
542 | * | |
543 | * Release the range of chardev nodes used for watchdog devices | |
544 | */ | |
545 | ||
546 | void __exit watchdog_dev_exit(void) | |
547 | { | |
548 | unregister_chrdev_region(watchdog_devt, MAX_DOGS); | |
549 | } |