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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
45/* make sure we only register one /dev/watchdog device */
46static unsigned long watchdog_dev_busy;
47/* the watchdog device behind /dev/watchdog */
48static struct watchdog_device *wdd;
49
50/*
51 * watchdog_ping: ping the watchdog.
52 * @wddev: the watchdog device to ping
53 *
54 * If the watchdog has no own ping operation then it needs to be
55 * restarted via the start operation. This wrapper function does
56 * exactly that.
57 * We only ping when the watchdog device is running.
58 */
59
60static int watchdog_ping(struct watchdog_device *wddev)
61{
62 if (test_bit(WDOG_ACTIVE, &wddev->status)) {
63 if (wddev->ops->ping)
64 return wddev->ops->ping(wddev); /* ping the watchdog */
65 else
66 return wddev->ops->start(wddev); /* restart watchdog */
67 }
68 return 0;
69}
70
71/*
72 * watchdog_start: wrapper to start the watchdog.
73 * @wddev: the watchdog device to start
74 *
75 * Start the watchdog if it is not active and mark it active.
76 * This function returns zero on success or a negative errno code for
77 * failure.
78 */
79
80static int watchdog_start(struct watchdog_device *wddev)
81{
82 int err;
83
84 if (!test_bit(WDOG_ACTIVE, &wddev->status)) {
85 err = wddev->ops->start(wddev);
86 if (err < 0)
87 return err;
88
89 set_bit(WDOG_ACTIVE, &wddev->status);
90 }
91 return 0;
92}
93
94/*
95 * watchdog_stop: wrapper to stop the watchdog.
96 * @wddev: the watchdog device to stop
97 *
98 * Stop the watchdog if it is still active and unmark it active.
99 * This function returns zero on success or a negative errno code for
100 * failure.
101 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
102 */
103
104static int watchdog_stop(struct watchdog_device *wddev)
105{
106 int err = -EBUSY;
107
108 if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) {
109 pr_info("%s: nowayout prevents watchdog to be stopped!\n",
110 wddev->info->identity);
111 return err;
112 }
113
114 if (test_bit(WDOG_ACTIVE, &wddev->status)) {
115 err = wddev->ops->stop(wddev);
116 if (err < 0)
117 return err;
118
119 clear_bit(WDOG_ACTIVE, &wddev->status);
120 }
121 return 0;
122}
123
124/*
125 * watchdog_write: writes to the watchdog.
126 * @file: file from VFS
127 * @data: user address of data
128 * @len: length of data
129 * @ppos: pointer to the file offset
130 *
131 * A write to a watchdog device is defined as a keepalive ping.
132 * Writing the magic 'V' sequence allows the next close to turn
133 * off the watchdog (if 'nowayout' is not set).
134 */
135
136static ssize_t watchdog_write(struct file *file, const char __user *data,
137 size_t len, loff_t *ppos)
138{
139 size_t i;
140 char c;
141
142 if (len == 0)
143 return 0;
144
145 /*
146 * Note: just in case someone wrote the magic character
147 * five months ago...
148 */
149 clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
150
151 /* scan to see whether or not we got the magic character */
152 for (i = 0; i != len; i++) {
153 if (get_user(c, data + i))
154 return -EFAULT;
155 if (c == 'V')
156 set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
157 }
158
159 /* someone wrote to us, so we send the watchdog a keepalive ping */
160 watchdog_ping(wdd);
161
162 return len;
163}
164
165/*
166 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
167 * @file: file handle to the device
168 * @cmd: watchdog command
169 * @arg: argument pointer
170 *
171 * The watchdog API defines a common set of functions for all watchdogs
172 * according to their available features.
173 */
174
175static long watchdog_ioctl(struct file *file, unsigned int cmd,
176 unsigned long arg)
177{
178 void __user *argp = (void __user *)arg;
179 int __user *p = argp;
180 unsigned int val;
181 int err;
182
183 if (wdd->ops->ioctl) {
184 err = wdd->ops->ioctl(wdd, cmd, arg);
185 if (err != -ENOIOCTLCMD)
186 return err;
187 }
188
189 switch (cmd) {
190 case WDIOC_GETSUPPORT:
191 return copy_to_user(argp, wdd->info,
192 sizeof(struct watchdog_info)) ? -EFAULT : 0;
193 case WDIOC_GETSTATUS:
194 val = wdd->ops->status ? wdd->ops->status(wdd) : 0;
195 return put_user(val, p);
196 case WDIOC_GETBOOTSTATUS:
197 return put_user(wdd->bootstatus, p);
198 case WDIOC_SETOPTIONS:
199 if (get_user(val, p))
200 return -EFAULT;
201 if (val & WDIOS_DISABLECARD) {
202 err = watchdog_stop(wdd);
203 if (err < 0)
204 return err;
205 }
206 if (val & WDIOS_ENABLECARD) {
207 err = watchdog_start(wdd);
208 if (err < 0)
209 return err;
210 }
211 return 0;
212 case WDIOC_KEEPALIVE:
213 if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
214 return -EOPNOTSUPP;
215 watchdog_ping(wdd);
216 return 0;
217 case WDIOC_SETTIMEOUT:
218 if ((wdd->ops->set_timeout == NULL) ||
219 !(wdd->info->options & WDIOF_SETTIMEOUT))
220 return -EOPNOTSUPP;
221 if (get_user(val, p))
222 return -EFAULT;
223 if ((wdd->max_timeout != 0) &&
224 (val < wdd->min_timeout || val > wdd->max_timeout))
225 return -EINVAL;
226 err = wdd->ops->set_timeout(wdd, val);
227 if (err < 0)
228 return err;
229 wdd->timeout = val;
230 /* If the watchdog is active then we send a keepalive ping
231 * to make sure that the watchdog keep's running (and if
232 * possible that it takes the new timeout) */
233 watchdog_ping(wdd);
234 /* Fall */
235 case WDIOC_GETTIMEOUT:
236 /* timeout == 0 means that we don't know the timeout */
237 if (wdd->timeout == 0)
238 return -EOPNOTSUPP;
239 return put_user(wdd->timeout, p);
240 default:
241 return -ENOTTY;
242 }
243}
244
245/*
246 * watchdog_open: open the /dev/watchdog device.
247 * @inode: inode of device
248 * @file: file handle to device
249 *
250 * When the /dev/watchdog device gets opened, we start the watchdog.
251 * Watch out: the /dev/watchdog device is single open, so we make sure
252 * it can only be opened once.
253 */
254
255static int watchdog_open(struct inode *inode, struct file *file)
256{
257 int err = -EBUSY;
258
259 /* the watchdog is single open! */
260 if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
261 return -EBUSY;
262
263 /*
264 * If the /dev/watchdog device is open, we don't want the module
265 * to be unloaded.
266 */
267 if (!try_module_get(wdd->ops->owner))
268 goto out;
269
270 err = watchdog_start(wdd);
271 if (err < 0)
272 goto out_mod;
273
274 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
275 return nonseekable_open(inode, file);
276
277out_mod:
278 module_put(wdd->ops->owner);
279out:
280 clear_bit(WDOG_DEV_OPEN, &wdd->status);
281 return err;
282}
283
284/*
285 * watchdog_release: release the /dev/watchdog device.
286 * @inode: inode of device
287 * @file: file handle to device
288 *
289 * This is the code for when /dev/watchdog gets closed. We will only
290 * stop the watchdog when we have received the magic char (and nowayout
291 * was not set), else the watchdog will keep running.
292 */
293
294static int watchdog_release(struct inode *inode, struct file *file)
295{
296 int err = -EBUSY;
297
298 /*
299 * We only stop the watchdog if we received the magic character
300 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
301 * watchdog_stop will fail.
302 */
303 if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
304 !(wdd->info->options & WDIOF_MAGICCLOSE))
305 err = watchdog_stop(wdd);
306
307 /* If the watchdog was not stopped, send a keepalive ping */
308 if (err < 0) {
309 pr_crit("%s: watchdog did not stop!\n", wdd->info->identity);
310 watchdog_ping(wdd);
311 }
312
313 /* Allow the owner module to be unloaded again */
314 module_put(wdd->ops->owner);
315
316 /* make sure that /dev/watchdog can be re-opened */
317 clear_bit(WDOG_DEV_OPEN, &wdd->status);
318
319 return 0;
320}
321
322static const struct file_operations watchdog_fops = {
323 .owner = THIS_MODULE,
324 .write = watchdog_write,
325 .unlocked_ioctl = watchdog_ioctl,
326 .open = watchdog_open,
327 .release = watchdog_release,
328};
329
330static struct miscdevice watchdog_miscdev = {
331 .minor = WATCHDOG_MINOR,
332 .name = "watchdog",
333 .fops = &watchdog_fops,
334};
335
336/*
337 * watchdog_dev_register:
338 * @watchdog: watchdog device
339 *
340 * Register a watchdog device as /dev/watchdog. /dev/watchdog
341 * is actually a miscdevice and thus we set it up like that.
342 */
343
344int watchdog_dev_register(struct watchdog_device *watchdog)
345{
346 int err;
347
348 /* Only one device can register for /dev/watchdog */
349 if (test_and_set_bit(0, &watchdog_dev_busy)) {
350 pr_err("only one watchdog can use /dev/watchdog.\n");
351 return -EBUSY;
352 }
353
354 wdd = watchdog;
355
356 err = misc_register(&watchdog_miscdev);
357 if (err != 0) {
358 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
359 watchdog->info->identity, WATCHDOG_MINOR, err);
360 goto out;
361 }
362
363 return 0;
364
365out:
366 wdd = NULL;
367 clear_bit(0, &watchdog_dev_busy);
368 return err;
369}
370
371/*
372 * watchdog_dev_unregister:
373 * @watchdog: watchdog device
374 *
375 * Deregister the /dev/watchdog device.
376 */
377
378int watchdog_dev_unregister(struct watchdog_device *watchdog)
379{
380 /* Check that a watchdog device was registered in the past */
381 if (!test_bit(0, &watchdog_dev_busy) || !wdd)
382 return -ENODEV;
383
384 /* We can only unregister the watchdog device that was registered */
385 if (watchdog != wdd) {
386 pr_err("%s: watchdog was not registered as /dev/watchdog.\n",
387 watchdog->info->identity);
388 return -ENODEV;
389 }
390
391 misc_deregister(&watchdog_miscdev);
392 wdd = NULL;
393 clear_bit(0, &watchdog_dev_busy);
394 return 0;
395}
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
45#include "watchdog_core.h"
46
47/* the dev_t structure to store the dynamically allocated watchdog devices */
48static dev_t watchdog_devt;
49/* the watchdog device behind /dev/watchdog */
50static struct watchdog_device *old_wdd;
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.
59 * We only ping when the watchdog device is running.
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); /* ping the watchdog */
78 else
79 err = wddev->ops->start(wddev); /* restart watchdog */
80
81out_ping:
82 mutex_unlock(&wddev->lock);
83 return err;
84}
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{
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 * 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.
125 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
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 * 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
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 * 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
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/*
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
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/*
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
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
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.
288 * Writing the magic 'V' sequence allows the next close to turn
289 * off the watchdog (if 'nowayout' is not set).
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 * 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 */
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 /* someone wrote to us, so we send the watchdog a keepalive ping */
317 watchdog_ping(wdd);
318
319 return len;
320}
321
322/*
323 * 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{
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 /* 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);
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
401/*
402 * watchdog_open: open the /dev/watchdog* devices.
403 * @inode: inode of device
404 * @file: file handle to device
405 *
406 * When the /dev/watchdog* device gets opened, we start the watchdog.
407 * 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;
414 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);
421
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
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 /* 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/*
453 * watchdog_release: release the watchdog device.
454 * @inode: inode of device
455 * @file: file handle to device
456 *
457 * This is the code for when /dev/watchdog gets closed. We will only
458 * stop the watchdog when we have received the magic char (and nowayout
459 * was not set), else the watchdog will keep running.
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 * We only stop the watchdog if we received the magic character
469 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
470 * watchdog_stop will fail.
471 */
472 if (!test_bit(WDOG_ACTIVE, &wdd->status))
473 err = 0;
474 else if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
475 !(wdd->info->options & WDIOF_MAGICCLOSE))
476 err = watchdog_stop(wdd);
477
478 /* If the watchdog was not stopped, send a keepalive ping */
479 if (err < 0) {
480 mutex_lock(&wdd->lock);
481 if (!test_bit(WDOG_UNREGISTERED, &wdd->status))
482 dev_crit(wdd->dev, "watchdog did not stop!\n");
483 mutex_unlock(&wdd->lock);
484 watchdog_ping(wdd);
485 }
486
487 /* Allow the owner module to be unloaded again */
488 module_put(wdd->ops->owner);
489
490 /* make sure that /dev/watchdog can be re-opened */
491 clear_bit(WDOG_DEV_OPEN, &wdd->status);
492
493 /* Note wdd may be gone after this, do not use after this! */
494 if (wdd->ops->unref)
495 wdd->ops->unref(wdd);
496
497 return 0;
498}
499
500static const struct file_operations watchdog_fops = {
501 .owner = THIS_MODULE,
502 .write = watchdog_write,
503 .unlocked_ioctl = watchdog_ioctl,
504 .open = watchdog_open,
505 .release = watchdog_release,
506};
507
508static struct miscdevice watchdog_miscdev = {
509 .minor = WATCHDOG_MINOR,
510 .name = "watchdog",
511 .fops = &watchdog_fops,
512};
513
514/*
515 * watchdog_dev_register: register a watchdog device
516 * @watchdog: watchdog device
517 *
518 * Register a watchdog device including handling the legacy
519 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
520 * thus we set it up like that.
521 */
522
523int watchdog_dev_register(struct watchdog_device *watchdog)
524{
525 int err, devno;
526
527 if (watchdog->id == 0) {
528 old_wdd = watchdog;
529 watchdog_miscdev.parent = watchdog->parent;
530 err = misc_register(&watchdog_miscdev);
531 if (err != 0) {
532 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
533 watchdog->info->identity, WATCHDOG_MINOR, err);
534 if (err == -EBUSY)
535 pr_err("%s: a legacy watchdog module is probably present.\n",
536 watchdog->info->identity);
537 old_wdd = NULL;
538 return err;
539 }
540 }
541
542 /* Fill in the data structures */
543 devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
544 cdev_init(&watchdog->cdev, &watchdog_fops);
545 watchdog->cdev.owner = watchdog->ops->owner;
546
547 /* Add the device */
548 err = cdev_add(&watchdog->cdev, devno, 1);
549 if (err) {
550 pr_err("watchdog%d unable to add device %d:%d\n",
551 watchdog->id, MAJOR(watchdog_devt), watchdog->id);
552 if (watchdog->id == 0) {
553 misc_deregister(&watchdog_miscdev);
554 old_wdd = NULL;
555 }
556 }
557 return err;
558}
559
560/*
561 * watchdog_dev_unregister: unregister a watchdog device
562 * @watchdog: watchdog device
563 *
564 * Unregister the watchdog and if needed the legacy /dev/watchdog device.
565 */
566
567int watchdog_dev_unregister(struct watchdog_device *watchdog)
568{
569 mutex_lock(&watchdog->lock);
570 set_bit(WDOG_UNREGISTERED, &watchdog->status);
571 mutex_unlock(&watchdog->lock);
572
573 cdev_del(&watchdog->cdev);
574 if (watchdog->id == 0) {
575 misc_deregister(&watchdog_miscdev);
576 old_wdd = NULL;
577 }
578 return 0;
579}
580
581/*
582 * watchdog_dev_init: init dev part of watchdog core
583 *
584 * Allocate a range of chardev nodes to use for watchdog devices
585 */
586
587int __init watchdog_dev_init(void)
588{
589 int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
590 if (err < 0)
591 pr_err("watchdog: unable to allocate char dev region\n");
592 return err;
593}
594
595/*
596 * watchdog_dev_exit: exit dev part of watchdog core
597 *
598 * Release the range of chardev nodes used for watchdog devices
599 */
600
601void __exit watchdog_dev_exit(void)
602{
603 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
604}