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Wim Van Sebroeck43316042011-07-22 18:55:18 +00001/*
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
Wim Van Sebroeck6cfb5aa2012-05-21 15:31:06 +020045#include "watchdog_core.h"
H Hartley Sweeten09a46e72012-04-20 13:28:24 -070046
Alan Cox45f5fed2012-05-10 21:48:59 +020047/* the dev_t structure to store the dynamically allocated watchdog devices */
48static dev_t watchdog_devt;
Wim Van Sebroeck43316042011-07-22 18:55:18 +000049/* the watchdog device behind /dev/watchdog */
Alan Cox45f5fed2012-05-10 21:48:59 +020050static struct watchdog_device *old_wdd;
Wim Van Sebroeck43316042011-07-22 18:55:18 +000051
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.
Wim Van Sebroeck234445b2011-07-22 18:57:55 +000059 * We only ping when the watchdog device is running.
Wim Van Sebroeck43316042011-07-22 18:55:18 +000060 */
61
62static int watchdog_ping(struct watchdog_device *wddev)
63{
Hans de Goede7a879822012-05-22 11:40:26 +020064 int err = 0;
65
Hans de Goedef4e9c822012-05-22 11:40:26 +020066 mutex_lock(&wddev->lock);
67
Hans de Goedee907df32012-05-22 11:40:26 +020068 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
69 err = -ENODEV;
70 goto out_ping;
71 }
72
Hans de Goede7a879822012-05-22 11:40:26 +020073 if (!watchdog_active(wddev))
74 goto out_ping;
75
76 if (wddev->ops->ping)
77 err = wddev->ops->ping(wddev); /* ping the watchdog */
78 else
79 err = wddev->ops->start(wddev); /* restart watchdog */
80
81out_ping:
Hans de Goedef4e9c822012-05-22 11:40:26 +020082 mutex_unlock(&wddev->lock);
Hans de Goede7a879822012-05-22 11:40:26 +020083 return err;
Wim Van Sebroeck234445b2011-07-22 18:57:55 +000084}
85
86/*
87 * watchdog_start: wrapper to start the watchdog.
88 * @wddev: the watchdog device to start
89 *
90 * Start the watchdog if it is not active and mark it active.
91 * This function returns zero on success or a negative errno code for
92 * failure.
93 */
94
95static int watchdog_start(struct watchdog_device *wddev)
96{
Hans de Goede7a879822012-05-22 11:40:26 +020097 int err = 0;
Wim Van Sebroeck234445b2011-07-22 18:57:55 +000098
Hans de Goedef4e9c822012-05-22 11:40:26 +020099 mutex_lock(&wddev->lock);
100
Hans de Goedee907df32012-05-22 11:40:26 +0200101 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
102 err = -ENODEV;
103 goto out_start;
104 }
105
Hans de Goede7a879822012-05-22 11:40:26 +0200106 if (watchdog_active(wddev))
107 goto out_start;
Wim Van Sebroeck234445b2011-07-22 18:57:55 +0000108
Hans de Goede7a879822012-05-22 11:40:26 +0200109 err = wddev->ops->start(wddev);
110 if (err == 0)
H Hartley Sweetencb7efc02011-08-03 15:38:20 -0700111 set_bit(WDOG_ACTIVE, &wddev->status);
Hans de Goede7a879822012-05-22 11:40:26 +0200112
113out_start:
Hans de Goedef4e9c822012-05-22 11:40:26 +0200114 mutex_unlock(&wddev->lock);
Hans de Goede7a879822012-05-22 11:40:26 +0200115 return err;
Wim Van Sebroeck234445b2011-07-22 18:57:55 +0000116}
117
118/*
119 * watchdog_stop: wrapper to stop the watchdog.
120 * @wddev: the watchdog device to stop
121 *
122 * Stop the watchdog if it is still active and unmark it active.
123 * This function returns zero on success or a negative errno code for
124 * failure.
Wim Van Sebroeck7e192b92011-07-22 18:59:17 +0000125 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
Wim Van Sebroeck234445b2011-07-22 18:57:55 +0000126 */
127
128static int watchdog_stop(struct watchdog_device *wddev)
129{
Hans de Goede7a879822012-05-22 11:40:26 +0200130 int err = 0;
131
Hans de Goedef4e9c822012-05-22 11:40:26 +0200132 mutex_lock(&wddev->lock);
133
Hans de Goedee907df32012-05-22 11:40:26 +0200134 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
135 err = -ENODEV;
136 goto out_stop;
137 }
138
Hans de Goede7a879822012-05-22 11:40:26 +0200139 if (!watchdog_active(wddev))
140 goto out_stop;
Wim Van Sebroeck7e192b92011-07-22 18:59:17 +0000141
H Hartley Sweetencb7efc02011-08-03 15:38:20 -0700142 if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) {
Alan Cox3dfd6212012-05-11 12:00:22 +0200143 dev_info(wddev->dev, "nowayout prevents watchdog being stopped!\n");
Hans de Goede7a879822012-05-22 11:40:26 +0200144 err = -EBUSY;
145 goto out_stop;
Wim Van Sebroeck7e192b92011-07-22 18:59:17 +0000146 }
Wim Van Sebroeck234445b2011-07-22 18:57:55 +0000147
Hans de Goede7a879822012-05-22 11:40:26 +0200148 err = wddev->ops->stop(wddev);
149 if (err == 0)
H Hartley Sweetencb7efc02011-08-03 15:38:20 -0700150 clear_bit(WDOG_ACTIVE, &wddev->status);
Hans de Goede7a879822012-05-22 11:40:26 +0200151
152out_stop:
Hans de Goedef4e9c822012-05-22 11:40:26 +0200153 mutex_unlock(&wddev->lock);
Hans de Goede7a879822012-05-22 11:40:26 +0200154 return err;
155}
156
157/*
158 * watchdog_get_status: wrapper to get the watchdog status
159 * @wddev: the watchdog device to get the status from
160 * @status: the status of the watchdog device
161 *
162 * Get the watchdog's status flags.
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
Hans de Goedef4e9c822012-05-22 11:40:26 +0200174 mutex_lock(&wddev->lock);
175
Hans de Goedee907df32012-05-22 11:40:26 +0200176 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
177 err = -ENODEV;
178 goto out_status;
179 }
180
Hans de Goede7a879822012-05-22 11:40:26 +0200181 *status = wddev->ops->status(wddev);
182
Hans de Goedee907df32012-05-22 11:40:26 +0200183out_status:
Hans de Goedef4e9c822012-05-22 11:40:26 +0200184 mutex_unlock(&wddev->lock);
Hans de Goede7a879822012-05-22 11:40:26 +0200185 return err;
186}
187
188/*
189 * watchdog_set_timeout: set the watchdog timer timeout
190 * @wddev: the watchdog device to set the timeout for
191 * @timeout: timeout to set in seconds
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
Fabio Porcedda30482532013-01-08 11:04:10 +0100203 if (watchdog_timeout_invalid(wddev, timeout))
Hans de Goede7a879822012-05-22 11:40:26 +0200204 return -EINVAL;
205
Hans de Goedef4e9c822012-05-22 11:40:26 +0200206 mutex_lock(&wddev->lock);
207
Hans de Goedee907df32012-05-22 11:40:26 +0200208 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
209 err = -ENODEV;
210 goto out_timeout;
211 }
212
Hans de Goede7a879822012-05-22 11:40:26 +0200213 err = wddev->ops->set_timeout(wddev, timeout);
214
Hans de Goedee907df32012-05-22 11:40:26 +0200215out_timeout:
Hans de Goedef4e9c822012-05-22 11:40:26 +0200216 mutex_unlock(&wddev->lock);
Hans de Goede7a879822012-05-22 11:40:26 +0200217 return err;
218}
219
220/*
221 * watchdog_get_timeleft: wrapper to get the time left before a reboot
222 * @wddev: the watchdog device to get the remaining time from
223 * @timeleft: the time that's left
224 *
225 * Get the time before a watchdog will reboot (if not pinged).
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
Hans de Goedef4e9c822012-05-22 11:40:26 +0200237 mutex_lock(&wddev->lock);
238
Hans de Goedee907df32012-05-22 11:40:26 +0200239 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
240 err = -ENODEV;
241 goto out_timeleft;
242 }
243
Hans de Goede7a879822012-05-22 11:40:26 +0200244 *timeleft = wddev->ops->get_timeleft(wddev);
245
Hans de Goedee907df32012-05-22 11:40:26 +0200246out_timeleft:
Hans de Goedef4e9c822012-05-22 11:40:26 +0200247 mutex_unlock(&wddev->lock);
Hans de Goede7a879822012-05-22 11:40:26 +0200248 return err;
249}
250
251/*
252 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
253 * @wddev: the watchdog device to do the ioctl on
254 * @cmd: watchdog command
255 * @arg: argument pointer
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
Hans de Goedef4e9c822012-05-22 11:40:26 +0200266 mutex_lock(&wddev->lock);
267
Hans de Goedee907df32012-05-22 11:40:26 +0200268 if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
269 err = -ENODEV;
270 goto out_ioctl;
271 }
272
Hans de Goede7a879822012-05-22 11:40:26 +0200273 err = wddev->ops->ioctl(wddev, cmd, arg);
274
Hans de Goedee907df32012-05-22 11:40:26 +0200275out_ioctl:
Hans de Goedef4e9c822012-05-22 11:40:26 +0200276 mutex_unlock(&wddev->lock);
Hans de Goede7a879822012-05-22 11:40:26 +0200277 return err;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000278}
279
280/*
281 * watchdog_write: writes to the watchdog.
282 * @file: file from VFS
283 * @data: user address of data
284 * @len: length of data
285 * @ppos: pointer to the file offset
286 *
287 * A write to a watchdog device is defined as a keepalive ping.
Wim Van Sebroeck017cf082011-07-22 18:58:54 +0000288 * Writing the magic 'V' sequence allows the next close to turn
Wim Van Sebroeck7e192b92011-07-22 18:59:17 +0000289 * off the watchdog (if 'nowayout' is not set).
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000290 */
291
292static ssize_t watchdog_write(struct file *file, const char __user *data,
293 size_t len, loff_t *ppos)
294{
Alan Cox45f5fed2012-05-10 21:48:59 +0200295 struct watchdog_device *wdd = file->private_data;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000296 size_t i;
297 char c;
298
299 if (len == 0)
300 return 0;
301
Wim Van Sebroeck017cf082011-07-22 18:58:54 +0000302 /*
303 * Note: just in case someone wrote the magic character
304 * five months ago...
305 */
306 clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
307
308 /* scan to see whether or not we got the magic character */
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000309 for (i = 0; i != len; i++) {
310 if (get_user(c, data + i))
311 return -EFAULT;
Wim Van Sebroeck017cf082011-07-22 18:58:54 +0000312 if (c == 'V')
313 set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000314 }
315
316 /* someone wrote to us, so we send the watchdog a keepalive ping */
317 watchdog_ping(wdd);
318
319 return len;
320}
321
322/*
Wim Van Sebroeck2fa03562011-07-22 18:56:38 +0000323 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
324 * @file: file handle to the device
325 * @cmd: watchdog command
326 * @arg: argument pointer
327 *
328 * The watchdog API defines a common set of functions for all watchdogs
329 * according to their available features.
330 */
331
332static long watchdog_ioctl(struct file *file, unsigned int cmd,
333 unsigned long arg)
334{
Alan Cox45f5fed2012-05-10 21:48:59 +0200335 struct watchdog_device *wdd = file->private_data;
Wim Van Sebroeck2fa03562011-07-22 18:56:38 +0000336 void __user *argp = (void __user *)arg;
337 int __user *p = argp;
338 unsigned int val;
Wim Van Sebroeck234445b2011-07-22 18:57:55 +0000339 int err;
Wim Van Sebroeck2fa03562011-07-22 18:56:38 +0000340
Hans de Goede7a879822012-05-22 11:40:26 +0200341 err = watchdog_ioctl_op(wdd, cmd, arg);
342 if (err != -ENOIOCTLCMD)
343 return err;
Wim Van Sebroeck78d88fc2011-07-22 18:59:49 +0000344
Wim Van Sebroeck2fa03562011-07-22 18:56:38 +0000345 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:
Hans de Goede7a879822012-05-22 11:40:26 +0200350 err = watchdog_get_status(wdd, &val);
Wim Van Sebroeck8b9468d2012-06-26 20:07:21 +0200351 if (err == -ENODEV)
Hans de Goede7a879822012-05-22 11:40:26 +0200352 return err;
Wim Van Sebroeck2fa03562011-07-22 18:56:38 +0000353 return put_user(val, p);
354 case WDIOC_GETBOOTSTATUS:
355 return put_user(wdd->bootstatus, p);
Wim Van Sebroeck234445b2011-07-22 18:57:55 +0000356 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;
Wim Van Sebroeckc2dc00e2011-07-22 18:57:23 +0000370 case WDIOC_KEEPALIVE:
371 if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
372 return -EOPNOTSUPP;
373 watchdog_ping(wdd);
374 return 0;
Wim Van Sebroeck014d6942011-07-22 18:58:21 +0000375 case WDIOC_SETTIMEOUT:
Wim Van Sebroeck014d6942011-07-22 18:58:21 +0000376 if (get_user(val, p))
377 return -EFAULT;
Hans de Goede7a879822012-05-22 11:40:26 +0200378 err = watchdog_set_timeout(wdd, val);
Wim Van Sebroeck014d6942011-07-22 18:58:21 +0000379 if (err < 0)
380 return err;
Wim Van Sebroeck014d6942011-07-22 18:58:21 +0000381 /* If the watchdog is active then we send a keepalive ping
382 * to make sure that the watchdog keep's running (and if
383 * possible that it takes the new timeout) */
384 watchdog_ping(wdd);
385 /* Fall */
386 case WDIOC_GETTIMEOUT:
387 /* timeout == 0 means that we don't know the timeout */
388 if (wdd->timeout == 0)
389 return -EOPNOTSUPP;
390 return put_user(wdd->timeout, p);
Viresh Kumarfd7b6732012-03-16 09:14:00 +0100391 case WDIOC_GETTIMELEFT:
Hans de Goede7a879822012-05-22 11:40:26 +0200392 err = watchdog_get_timeleft(wdd, &val);
393 if (err)
394 return err;
395 return put_user(val, p);
Wim Van Sebroeck2fa03562011-07-22 18:56:38 +0000396 default:
397 return -ENOTTY;
398 }
399}
400
401/*
Alan Cox45f5fed2012-05-10 21:48:59 +0200402 * watchdog_open: open the /dev/watchdog* devices.
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000403 * @inode: inode of device
404 * @file: file handle to device
405 *
Alan Cox45f5fed2012-05-10 21:48:59 +0200406 * When the /dev/watchdog* device gets opened, we start the watchdog.
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000407 * Watch out: the /dev/watchdog device is single open, so we make sure
408 * it can only be opened once.
409 */
410
411static int watchdog_open(struct inode *inode, struct file *file)
412{
413 int err = -EBUSY;
Alan Cox45f5fed2012-05-10 21:48:59 +0200414 struct watchdog_device *wdd;
415
416 /* Get the corresponding watchdog device */
417 if (imajor(inode) == MISC_MAJOR)
418 wdd = old_wdd;
419 else
420 wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000421
422 /* the watchdog is single open! */
423 if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
424 return -EBUSY;
425
426 /*
427 * If the /dev/watchdog device is open, we don't want the module
428 * to be unloaded.
429 */
430 if (!try_module_get(wdd->ops->owner))
431 goto out;
432
Wim Van Sebroeck234445b2011-07-22 18:57:55 +0000433 err = watchdog_start(wdd);
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000434 if (err < 0)
435 goto out_mod;
436
Alan Cox45f5fed2012-05-10 21:48:59 +0200437 file->private_data = wdd;
438
Hans de Goedee907df32012-05-22 11:40:26 +0200439 if (wdd->ops->ref)
440 wdd->ops->ref(wdd);
441
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000442 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
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
452/*
Alan Cox45f5fed2012-05-10 21:48:59 +0200453 * watchdog_release: release the watchdog device.
454 * @inode: inode of device
455 * @file: file handle to device
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000456 *
Wim Van Sebroeck017cf082011-07-22 18:58:54 +0000457 * This is the code for when /dev/watchdog gets closed. We will only
Wim Van Sebroeck7e192b92011-07-22 18:59:17 +0000458 * stop the watchdog when we have received the magic char (and nowayout
459 * was not set), else the watchdog will keep running.
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000460 */
461
462static int watchdog_release(struct inode *inode, struct file *file)
463{
Alan Cox45f5fed2012-05-10 21:48:59 +0200464 struct watchdog_device *wdd = file->private_data;
Wim Van Sebroeck017cf082011-07-22 18:58:54 +0000465 int err = -EBUSY;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000466
Wim Van Sebroeck017cf082011-07-22 18:58:54 +0000467 /*
468 * We only stop the watchdog if we received the magic character
Wim Van Sebroeck7e192b92011-07-22 18:59:17 +0000469 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
470 * watchdog_stop will fail.
Wim Van Sebroeck017cf082011-07-22 18:58:54 +0000471 */
472 if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
473 !(wdd->info->options & WDIOF_MAGICCLOSE))
474 err = watchdog_stop(wdd);
475
476 /* If the watchdog was not stopped, send a keepalive ping */
Wim Van Sebroeck234445b2011-07-22 18:57:55 +0000477 if (err < 0) {
Hans de Goedee907df32012-05-22 11:40:26 +0200478 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);
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000482 watchdog_ping(wdd);
483 }
484
485 /* Allow the owner module to be unloaded again */
486 module_put(wdd->ops->owner);
487
488 /* make sure that /dev/watchdog can be re-opened */
489 clear_bit(WDOG_DEV_OPEN, &wdd->status);
490
Hans de Goedee907df32012-05-22 11:40:26 +0200491 /* Note wdd may be gone after this, do not use after this! */
492 if (wdd->ops->unref)
493 wdd->ops->unref(wdd);
494
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000495 return 0;
496}
497
498static const struct file_operations watchdog_fops = {
499 .owner = THIS_MODULE,
500 .write = watchdog_write,
Wim Van Sebroeck2fa03562011-07-22 18:56:38 +0000501 .unlocked_ioctl = watchdog_ioctl,
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000502 .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/*
Alan Cox45f5fed2012-05-10 21:48:59 +0200513 * watchdog_dev_register: register a watchdog device
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000514 * @watchdog: watchdog device
515 *
Alan Cox45f5fed2012-05-10 21:48:59 +0200516 * Register a watchdog device including handling the legacy
517 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
518 * thus we set it up like that.
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000519 */
520
521int watchdog_dev_register(struct watchdog_device *watchdog)
522{
Alan Cox45f5fed2012-05-10 21:48:59 +0200523 int err, devno;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000524
Alan Cox45f5fed2012-05-10 21:48:59 +0200525 if (watchdog->id == 0) {
Guenter Roeck60403f72013-04-05 21:22:43 -0700526 old_wdd = watchdog;
Alan Coxd6b469d2012-05-11 12:00:20 +0200527 watchdog_miscdev.parent = watchdog->parent;
Alan Cox45f5fed2012-05-10 21:48:59 +0200528 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);
Guenter Roeck60403f72013-04-05 21:22:43 -0700535 old_wdd = NULL;
Alan Cox45f5fed2012-05-10 21:48:59 +0200536 return err;
537 }
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000538 }
539
Alan Cox45f5fed2012-05-10 21:48:59 +0200540 /* Fill in the data structures */
541 devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
542 cdev_init(&watchdog->cdev, &watchdog_fops);
543 watchdog->cdev.owner = watchdog->ops->owner;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000544
Alan Cox45f5fed2012-05-10 21:48:59 +0200545 /* Add the device */
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 }
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000554 }
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000555 return err;
556}
557
558/*
Alan Cox45f5fed2012-05-10 21:48:59 +0200559 * watchdog_dev_unregister: unregister a watchdog device
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000560 * @watchdog: watchdog device
561 *
Alan Cox45f5fed2012-05-10 21:48:59 +0200562 * Unregister the watchdog and if needed the legacy /dev/watchdog device.
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000563 */
564
565int watchdog_dev_unregister(struct watchdog_device *watchdog)
566{
Hans de Goedee907df32012-05-22 11:40:26 +0200567 mutex_lock(&watchdog->lock);
568 set_bit(WDOG_UNREGISTERED, &watchdog->status);
569 mutex_unlock(&watchdog->lock);
570
Alan Cox45f5fed2012-05-10 21:48:59 +0200571 cdev_del(&watchdog->cdev);
572 if (watchdog->id == 0) {
573 misc_deregister(&watchdog_miscdev);
574 old_wdd = NULL;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000575 }
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000576 return 0;
577}
Alan Cox45f5fed2012-05-10 21:48:59 +0200578
579/*
580 * watchdog_dev_init: init dev part of watchdog core
581 *
582 * Allocate a range of chardev nodes to use for watchdog devices
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 * watchdog_dev_exit: exit dev part of watchdog core
595 *
596 * Release the range of chardev nodes used for watchdog devices
597 */
598
599void __exit watchdog_dev_exit(void)
600{
601 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
602}