Loading...
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/cdev.h> /* For character device */
36#include <linux/errno.h> /* For the -ENODEV/... values */
37#include <linux/fs.h> /* For file operations */
38#include <linux/init.h> /* For __init/__exit/... */
39#include <linux/jiffies.h> /* For timeout functions */
40#include <linux/kernel.h> /* For printk/panic/... */
41#include <linux/kref.h> /* For data references */
42#include <linux/miscdevice.h> /* For handling misc devices */
43#include <linux/module.h> /* For module stuff/... */
44#include <linux/mutex.h> /* For mutexes */
45#include <linux/slab.h> /* For memory functions */
46#include <linux/types.h> /* For standard types (like size_t) */
47#include <linux/watchdog.h> /* For watchdog specific items */
48#include <linux/workqueue.h> /* For workqueue */
49#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
50
51#include "watchdog_core.h"
52
53/*
54 * struct watchdog_core_data - watchdog core internal data
55 * @kref: Reference count.
56 * @cdev: The watchdog's Character device.
57 * @wdd: Pointer to watchdog device.
58 * @lock: Lock for watchdog core.
59 * @status: Watchdog core internal status bits.
60 */
61struct watchdog_core_data {
62 struct kref kref;
63 struct cdev cdev;
64 struct watchdog_device *wdd;
65 struct mutex lock;
66 unsigned long last_keepalive;
67 unsigned long last_hw_keepalive;
68 struct delayed_work work;
69 unsigned long status; /* Internal status bits */
70#define _WDOG_DEV_OPEN 0 /* Opened ? */
71#define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
72};
73
74/* the dev_t structure to store the dynamically allocated watchdog devices */
75static dev_t watchdog_devt;
76/* Reference to watchdog device behind /dev/watchdog */
77static struct watchdog_core_data *old_wd_data;
78
79static struct workqueue_struct *watchdog_wq;
80
81static inline bool watchdog_need_worker(struct watchdog_device *wdd)
82{
83 /* All variables in milli-seconds */
84 unsigned int hm = wdd->max_hw_heartbeat_ms;
85 unsigned int t = wdd->timeout * 1000;
86
87 /*
88 * A worker to generate heartbeat requests is needed if all of the
89 * following conditions are true.
90 * - Userspace activated the watchdog.
91 * - The driver provided a value for the maximum hardware timeout, and
92 * thus is aware that the framework supports generating heartbeat
93 * requests.
94 * - Userspace requests a longer timeout than the hardware can handle.
95 */
96 return hm && ((watchdog_active(wdd) && t > hm) ||
97 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd)));
98}
99
100static long watchdog_next_keepalive(struct watchdog_device *wdd)
101{
102 struct watchdog_core_data *wd_data = wdd->wd_data;
103 unsigned int timeout_ms = wdd->timeout * 1000;
104 unsigned long keepalive_interval;
105 unsigned long last_heartbeat;
106 unsigned long virt_timeout;
107 unsigned int hw_heartbeat_ms;
108
109 virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
110 hw_heartbeat_ms = min(timeout_ms, wdd->max_hw_heartbeat_ms);
111 keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);
112
113 if (!watchdog_active(wdd))
114 return keepalive_interval;
115
116 /*
117 * To ensure that the watchdog times out wdd->timeout seconds
118 * after the most recent ping from userspace, the last
119 * worker ping has to come in hw_heartbeat_ms before this timeout.
120 */
121 last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
122 return min_t(long, last_heartbeat - jiffies, keepalive_interval);
123}
124
125static inline void watchdog_update_worker(struct watchdog_device *wdd)
126{
127 struct watchdog_core_data *wd_data = wdd->wd_data;
128
129 if (watchdog_need_worker(wdd)) {
130 long t = watchdog_next_keepalive(wdd);
131
132 if (t > 0)
133 mod_delayed_work(watchdog_wq, &wd_data->work, t);
134 } else {
135 cancel_delayed_work(&wd_data->work);
136 }
137}
138
139static int __watchdog_ping(struct watchdog_device *wdd)
140{
141 struct watchdog_core_data *wd_data = wdd->wd_data;
142 unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
143 msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
144 int err;
145
146 if (time_is_after_jiffies(earliest_keepalive)) {
147 mod_delayed_work(watchdog_wq, &wd_data->work,
148 earliest_keepalive - jiffies);
149 return 0;
150 }
151
152 wd_data->last_hw_keepalive = jiffies;
153
154 if (wdd->ops->ping)
155 err = wdd->ops->ping(wdd); /* ping the watchdog */
156 else
157 err = wdd->ops->start(wdd); /* restart watchdog */
158
159 watchdog_update_worker(wdd);
160
161 return err;
162}
163
164/*
165 * watchdog_ping: ping the watchdog.
166 * @wdd: the watchdog device to ping
167 *
168 * The caller must hold wd_data->lock.
169 *
170 * If the watchdog has no own ping operation then it needs to be
171 * restarted via the start operation. This wrapper function does
172 * exactly that.
173 * We only ping when the watchdog device is running.
174 */
175
176static int watchdog_ping(struct watchdog_device *wdd)
177{
178 struct watchdog_core_data *wd_data = wdd->wd_data;
179
180 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
181 return 0;
182
183 wd_data->last_keepalive = jiffies;
184 return __watchdog_ping(wdd);
185}
186
187static void watchdog_ping_work(struct work_struct *work)
188{
189 struct watchdog_core_data *wd_data;
190 struct watchdog_device *wdd;
191
192 wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
193 work);
194
195 mutex_lock(&wd_data->lock);
196 wdd = wd_data->wdd;
197 if (wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd)))
198 __watchdog_ping(wdd);
199 mutex_unlock(&wd_data->lock);
200}
201
202/*
203 * watchdog_start: wrapper to start the watchdog.
204 * @wdd: the watchdog device to start
205 *
206 * The caller must hold wd_data->lock.
207 *
208 * Start the watchdog if it is not active and mark it active.
209 * This function returns zero on success or a negative errno code for
210 * failure.
211 */
212
213static int watchdog_start(struct watchdog_device *wdd)
214{
215 struct watchdog_core_data *wd_data = wdd->wd_data;
216 unsigned long started_at;
217 int err;
218
219 if (watchdog_active(wdd))
220 return 0;
221
222 started_at = jiffies;
223 if (watchdog_hw_running(wdd) && wdd->ops->ping)
224 err = wdd->ops->ping(wdd);
225 else
226 err = wdd->ops->start(wdd);
227 if (err == 0) {
228 set_bit(WDOG_ACTIVE, &wdd->status);
229 wd_data->last_keepalive = started_at;
230 watchdog_update_worker(wdd);
231 }
232
233 return err;
234}
235
236/*
237 * watchdog_stop: wrapper to stop the watchdog.
238 * @wdd: the watchdog device to stop
239 *
240 * The caller must hold wd_data->lock.
241 *
242 * Stop the watchdog if it is still active and unmark it active.
243 * This function returns zero on success or a negative errno code for
244 * failure.
245 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
246 */
247
248static int watchdog_stop(struct watchdog_device *wdd)
249{
250 int err = 0;
251
252 if (!watchdog_active(wdd))
253 return 0;
254
255 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
256 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
257 wdd->id);
258 return -EBUSY;
259 }
260
261 if (wdd->ops->stop)
262 err = wdd->ops->stop(wdd);
263 else
264 set_bit(WDOG_HW_RUNNING, &wdd->status);
265
266 if (err == 0) {
267 clear_bit(WDOG_ACTIVE, &wdd->status);
268 watchdog_update_worker(wdd);
269 }
270
271 return err;
272}
273
274/*
275 * watchdog_get_status: wrapper to get the watchdog status
276 * @wdd: the watchdog device to get the status from
277 *
278 * The caller must hold wd_data->lock.
279 *
280 * Get the watchdog's status flags.
281 */
282
283static unsigned int watchdog_get_status(struct watchdog_device *wdd)
284{
285 if (!wdd->ops->status)
286 return 0;
287
288 return wdd->ops->status(wdd);
289}
290
291/*
292 * watchdog_set_timeout: set the watchdog timer timeout
293 * @wdd: the watchdog device to set the timeout for
294 * @timeout: timeout to set in seconds
295 *
296 * The caller must hold wd_data->lock.
297 */
298
299static int watchdog_set_timeout(struct watchdog_device *wdd,
300 unsigned int timeout)
301{
302 int err = 0;
303
304 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
305 return -EOPNOTSUPP;
306
307 if (watchdog_timeout_invalid(wdd, timeout))
308 return -EINVAL;
309
310 if (wdd->ops->set_timeout)
311 err = wdd->ops->set_timeout(wdd, timeout);
312 else
313 wdd->timeout = timeout;
314
315 watchdog_update_worker(wdd);
316
317 return err;
318}
319
320/*
321 * watchdog_get_timeleft: wrapper to get the time left before a reboot
322 * @wdd: the watchdog device to get the remaining time from
323 * @timeleft: the time that's left
324 *
325 * The caller must hold wd_data->lock.
326 *
327 * Get the time before a watchdog will reboot (if not pinged).
328 */
329
330static int watchdog_get_timeleft(struct watchdog_device *wdd,
331 unsigned int *timeleft)
332{
333 *timeleft = 0;
334
335 if (!wdd->ops->get_timeleft)
336 return -EOPNOTSUPP;
337
338 *timeleft = wdd->ops->get_timeleft(wdd);
339
340 return 0;
341}
342
343#ifdef CONFIG_WATCHDOG_SYSFS
344static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
345 char *buf)
346{
347 struct watchdog_device *wdd = dev_get_drvdata(dev);
348
349 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
350}
351static DEVICE_ATTR_RO(nowayout);
352
353static ssize_t status_show(struct device *dev, struct device_attribute *attr,
354 char *buf)
355{
356 struct watchdog_device *wdd = dev_get_drvdata(dev);
357 struct watchdog_core_data *wd_data = wdd->wd_data;
358 unsigned int status;
359
360 mutex_lock(&wd_data->lock);
361 status = watchdog_get_status(wdd);
362 mutex_unlock(&wd_data->lock);
363
364 return sprintf(buf, "%u\n", status);
365}
366static DEVICE_ATTR_RO(status);
367
368static ssize_t bootstatus_show(struct device *dev,
369 struct device_attribute *attr, char *buf)
370{
371 struct watchdog_device *wdd = dev_get_drvdata(dev);
372
373 return sprintf(buf, "%u\n", wdd->bootstatus);
374}
375static DEVICE_ATTR_RO(bootstatus);
376
377static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
378 char *buf)
379{
380 struct watchdog_device *wdd = dev_get_drvdata(dev);
381 struct watchdog_core_data *wd_data = wdd->wd_data;
382 ssize_t status;
383 unsigned int val;
384
385 mutex_lock(&wd_data->lock);
386 status = watchdog_get_timeleft(wdd, &val);
387 mutex_unlock(&wd_data->lock);
388 if (!status)
389 status = sprintf(buf, "%u\n", val);
390
391 return status;
392}
393static DEVICE_ATTR_RO(timeleft);
394
395static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
396 char *buf)
397{
398 struct watchdog_device *wdd = dev_get_drvdata(dev);
399
400 return sprintf(buf, "%u\n", wdd->timeout);
401}
402static DEVICE_ATTR_RO(timeout);
403
404static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
405 char *buf)
406{
407 struct watchdog_device *wdd = dev_get_drvdata(dev);
408
409 return sprintf(buf, "%s\n", wdd->info->identity);
410}
411static DEVICE_ATTR_RO(identity);
412
413static ssize_t state_show(struct device *dev, struct device_attribute *attr,
414 char *buf)
415{
416 struct watchdog_device *wdd = dev_get_drvdata(dev);
417
418 if (watchdog_active(wdd))
419 return sprintf(buf, "active\n");
420
421 return sprintf(buf, "inactive\n");
422}
423static DEVICE_ATTR_RO(state);
424
425static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
426 int n)
427{
428 struct device *dev = container_of(kobj, struct device, kobj);
429 struct watchdog_device *wdd = dev_get_drvdata(dev);
430 umode_t mode = attr->mode;
431
432 if (attr == &dev_attr_status.attr && !wdd->ops->status)
433 mode = 0;
434 else if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
435 mode = 0;
436
437 return mode;
438}
439static struct attribute *wdt_attrs[] = {
440 &dev_attr_state.attr,
441 &dev_attr_identity.attr,
442 &dev_attr_timeout.attr,
443 &dev_attr_timeleft.attr,
444 &dev_attr_bootstatus.attr,
445 &dev_attr_status.attr,
446 &dev_attr_nowayout.attr,
447 NULL,
448};
449
450static const struct attribute_group wdt_group = {
451 .attrs = wdt_attrs,
452 .is_visible = wdt_is_visible,
453};
454__ATTRIBUTE_GROUPS(wdt);
455#else
456#define wdt_groups NULL
457#endif
458
459/*
460 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
461 * @wdd: the watchdog device to do the ioctl on
462 * @cmd: watchdog command
463 * @arg: argument pointer
464 *
465 * The caller must hold wd_data->lock.
466 */
467
468static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
469 unsigned long arg)
470{
471 if (!wdd->ops->ioctl)
472 return -ENOIOCTLCMD;
473
474 return wdd->ops->ioctl(wdd, cmd, arg);
475}
476
477/*
478 * watchdog_write: writes to the watchdog.
479 * @file: file from VFS
480 * @data: user address of data
481 * @len: length of data
482 * @ppos: pointer to the file offset
483 *
484 * A write to a watchdog device is defined as a keepalive ping.
485 * Writing the magic 'V' sequence allows the next close to turn
486 * off the watchdog (if 'nowayout' is not set).
487 */
488
489static ssize_t watchdog_write(struct file *file, const char __user *data,
490 size_t len, loff_t *ppos)
491{
492 struct watchdog_core_data *wd_data = file->private_data;
493 struct watchdog_device *wdd;
494 int err;
495 size_t i;
496 char c;
497
498 if (len == 0)
499 return 0;
500
501 /*
502 * Note: just in case someone wrote the magic character
503 * five months ago...
504 */
505 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
506
507 /* scan to see whether or not we got the magic character */
508 for (i = 0; i != len; i++) {
509 if (get_user(c, data + i))
510 return -EFAULT;
511 if (c == 'V')
512 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
513 }
514
515 /* someone wrote to us, so we send the watchdog a keepalive ping */
516
517 err = -ENODEV;
518 mutex_lock(&wd_data->lock);
519 wdd = wd_data->wdd;
520 if (wdd)
521 err = watchdog_ping(wdd);
522 mutex_unlock(&wd_data->lock);
523
524 if (err < 0)
525 return err;
526
527 return len;
528}
529
530/*
531 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
532 * @file: file handle to the device
533 * @cmd: watchdog command
534 * @arg: argument pointer
535 *
536 * The watchdog API defines a common set of functions for all watchdogs
537 * according to their available features.
538 */
539
540static long watchdog_ioctl(struct file *file, unsigned int cmd,
541 unsigned long arg)
542{
543 struct watchdog_core_data *wd_data = file->private_data;
544 void __user *argp = (void __user *)arg;
545 struct watchdog_device *wdd;
546 int __user *p = argp;
547 unsigned int val;
548 int err;
549
550 mutex_lock(&wd_data->lock);
551
552 wdd = wd_data->wdd;
553 if (!wdd) {
554 err = -ENODEV;
555 goto out_ioctl;
556 }
557
558 err = watchdog_ioctl_op(wdd, cmd, arg);
559 if (err != -ENOIOCTLCMD)
560 goto out_ioctl;
561
562 switch (cmd) {
563 case WDIOC_GETSUPPORT:
564 err = copy_to_user(argp, wdd->info,
565 sizeof(struct watchdog_info)) ? -EFAULT : 0;
566 break;
567 case WDIOC_GETSTATUS:
568 val = watchdog_get_status(wdd);
569 err = put_user(val, p);
570 break;
571 case WDIOC_GETBOOTSTATUS:
572 err = put_user(wdd->bootstatus, p);
573 break;
574 case WDIOC_SETOPTIONS:
575 if (get_user(val, p)) {
576 err = -EFAULT;
577 break;
578 }
579 if (val & WDIOS_DISABLECARD) {
580 err = watchdog_stop(wdd);
581 if (err < 0)
582 break;
583 }
584 if (val & WDIOS_ENABLECARD)
585 err = watchdog_start(wdd);
586 break;
587 case WDIOC_KEEPALIVE:
588 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
589 err = -EOPNOTSUPP;
590 break;
591 }
592 err = watchdog_ping(wdd);
593 break;
594 case WDIOC_SETTIMEOUT:
595 if (get_user(val, p)) {
596 err = -EFAULT;
597 break;
598 }
599 err = watchdog_set_timeout(wdd, val);
600 if (err < 0)
601 break;
602 /* If the watchdog is active then we send a keepalive ping
603 * to make sure that the watchdog keep's running (and if
604 * possible that it takes the new timeout) */
605 err = watchdog_ping(wdd);
606 if (err < 0)
607 break;
608 /* Fall */
609 case WDIOC_GETTIMEOUT:
610 /* timeout == 0 means that we don't know the timeout */
611 if (wdd->timeout == 0) {
612 err = -EOPNOTSUPP;
613 break;
614 }
615 err = put_user(wdd->timeout, p);
616 break;
617 case WDIOC_GETTIMELEFT:
618 err = watchdog_get_timeleft(wdd, &val);
619 if (err < 0)
620 break;
621 err = put_user(val, p);
622 break;
623 default:
624 err = -ENOTTY;
625 break;
626 }
627
628out_ioctl:
629 mutex_unlock(&wd_data->lock);
630 return err;
631}
632
633/*
634 * watchdog_open: open the /dev/watchdog* devices.
635 * @inode: inode of device
636 * @file: file handle to device
637 *
638 * When the /dev/watchdog* device gets opened, we start the watchdog.
639 * Watch out: the /dev/watchdog device is single open, so we make sure
640 * it can only be opened once.
641 */
642
643static int watchdog_open(struct inode *inode, struct file *file)
644{
645 struct watchdog_core_data *wd_data;
646 struct watchdog_device *wdd;
647 int err;
648
649 /* Get the corresponding watchdog device */
650 if (imajor(inode) == MISC_MAJOR)
651 wd_data = old_wd_data;
652 else
653 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
654 cdev);
655
656 /* the watchdog is single open! */
657 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
658 return -EBUSY;
659
660 wdd = wd_data->wdd;
661
662 /*
663 * If the /dev/watchdog device is open, we don't want the module
664 * to be unloaded.
665 */
666 if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
667 err = -EBUSY;
668 goto out_clear;
669 }
670
671 err = watchdog_start(wdd);
672 if (err < 0)
673 goto out_mod;
674
675 file->private_data = wd_data;
676
677 if (!watchdog_hw_running(wdd))
678 kref_get(&wd_data->kref);
679
680 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
681 return nonseekable_open(inode, file);
682
683out_mod:
684 module_put(wd_data->wdd->ops->owner);
685out_clear:
686 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
687 return err;
688}
689
690static void watchdog_core_data_release(struct kref *kref)
691{
692 struct watchdog_core_data *wd_data;
693
694 wd_data = container_of(kref, struct watchdog_core_data, kref);
695
696 kfree(wd_data);
697}
698
699/*
700 * watchdog_release: release the watchdog device.
701 * @inode: inode of device
702 * @file: file handle to device
703 *
704 * This is the code for when /dev/watchdog gets closed. We will only
705 * stop the watchdog when we have received the magic char (and nowayout
706 * was not set), else the watchdog will keep running.
707 */
708
709static int watchdog_release(struct inode *inode, struct file *file)
710{
711 struct watchdog_core_data *wd_data = file->private_data;
712 struct watchdog_device *wdd;
713 int err = -EBUSY;
714 bool running;
715
716 mutex_lock(&wd_data->lock);
717
718 wdd = wd_data->wdd;
719 if (!wdd)
720 goto done;
721
722 /*
723 * We only stop the watchdog if we received the magic character
724 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
725 * watchdog_stop will fail.
726 */
727 if (!test_bit(WDOG_ACTIVE, &wdd->status))
728 err = 0;
729 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
730 !(wdd->info->options & WDIOF_MAGICCLOSE))
731 err = watchdog_stop(wdd);
732
733 /* If the watchdog was not stopped, send a keepalive ping */
734 if (err < 0) {
735 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
736 watchdog_ping(wdd);
737 }
738
739 cancel_delayed_work_sync(&wd_data->work);
740 watchdog_update_worker(wdd);
741
742 /* make sure that /dev/watchdog can be re-opened */
743 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
744
745done:
746 running = wdd && watchdog_hw_running(wdd);
747 mutex_unlock(&wd_data->lock);
748 /*
749 * Allow the owner module to be unloaded again unless the watchdog
750 * is still running. If the watchdog is still running, it can not
751 * be stopped, and its driver must not be unloaded.
752 */
753 if (!running) {
754 module_put(wd_data->cdev.owner);
755 kref_put(&wd_data->kref, watchdog_core_data_release);
756 }
757 return 0;
758}
759
760static const struct file_operations watchdog_fops = {
761 .owner = THIS_MODULE,
762 .write = watchdog_write,
763 .unlocked_ioctl = watchdog_ioctl,
764 .open = watchdog_open,
765 .release = watchdog_release,
766};
767
768static struct miscdevice watchdog_miscdev = {
769 .minor = WATCHDOG_MINOR,
770 .name = "watchdog",
771 .fops = &watchdog_fops,
772};
773
774/*
775 * watchdog_cdev_register: register watchdog character device
776 * @wdd: watchdog device
777 * @devno: character device number
778 *
779 * Register a watchdog character device including handling the legacy
780 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
781 * thus we set it up like that.
782 */
783
784static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
785{
786 struct watchdog_core_data *wd_data;
787 int err;
788
789 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
790 if (!wd_data)
791 return -ENOMEM;
792 kref_init(&wd_data->kref);
793 mutex_init(&wd_data->lock);
794
795 wd_data->wdd = wdd;
796 wdd->wd_data = wd_data;
797
798 if (!watchdog_wq)
799 return -ENODEV;
800
801 INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
802
803 if (wdd->id == 0) {
804 old_wd_data = wd_data;
805 watchdog_miscdev.parent = wdd->parent;
806 err = misc_register(&watchdog_miscdev);
807 if (err != 0) {
808 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
809 wdd->info->identity, WATCHDOG_MINOR, err);
810 if (err == -EBUSY)
811 pr_err("%s: a legacy watchdog module is probably present.\n",
812 wdd->info->identity);
813 old_wd_data = NULL;
814 kfree(wd_data);
815 return err;
816 }
817 }
818
819 /* Fill in the data structures */
820 cdev_init(&wd_data->cdev, &watchdog_fops);
821 wd_data->cdev.owner = wdd->ops->owner;
822
823 /* Add the device */
824 err = cdev_add(&wd_data->cdev, devno, 1);
825 if (err) {
826 pr_err("watchdog%d unable to add device %d:%d\n",
827 wdd->id, MAJOR(watchdog_devt), wdd->id);
828 if (wdd->id == 0) {
829 misc_deregister(&watchdog_miscdev);
830 old_wd_data = NULL;
831 kref_put(&wd_data->kref, watchdog_core_data_release);
832 }
833 return err;
834 }
835
836 /* Record time of most recent heartbeat as 'just before now'. */
837 wd_data->last_hw_keepalive = jiffies - 1;
838
839 /*
840 * If the watchdog is running, prevent its driver from being unloaded,
841 * and schedule an immediate ping.
842 */
843 if (watchdog_hw_running(wdd)) {
844 __module_get(wdd->ops->owner);
845 kref_get(&wd_data->kref);
846 queue_delayed_work(watchdog_wq, &wd_data->work, 0);
847 }
848
849 return 0;
850}
851
852/*
853 * watchdog_cdev_unregister: unregister watchdog character device
854 * @watchdog: watchdog device
855 *
856 * Unregister watchdog character device and if needed the legacy
857 * /dev/watchdog device.
858 */
859
860static void watchdog_cdev_unregister(struct watchdog_device *wdd)
861{
862 struct watchdog_core_data *wd_data = wdd->wd_data;
863
864 cdev_del(&wd_data->cdev);
865 if (wdd->id == 0) {
866 misc_deregister(&watchdog_miscdev);
867 old_wd_data = NULL;
868 }
869
870 mutex_lock(&wd_data->lock);
871 wd_data->wdd = NULL;
872 wdd->wd_data = NULL;
873 mutex_unlock(&wd_data->lock);
874
875 cancel_delayed_work_sync(&wd_data->work);
876
877 kref_put(&wd_data->kref, watchdog_core_data_release);
878}
879
880static struct class watchdog_class = {
881 .name = "watchdog",
882 .owner = THIS_MODULE,
883 .dev_groups = wdt_groups,
884};
885
886/*
887 * watchdog_dev_register: register a watchdog device
888 * @wdd: watchdog device
889 *
890 * Register a watchdog device including handling the legacy
891 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
892 * thus we set it up like that.
893 */
894
895int watchdog_dev_register(struct watchdog_device *wdd)
896{
897 struct device *dev;
898 dev_t devno;
899 int ret;
900
901 devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
902
903 ret = watchdog_cdev_register(wdd, devno);
904 if (ret)
905 return ret;
906
907 dev = device_create_with_groups(&watchdog_class, wdd->parent,
908 devno, wdd, wdd->groups,
909 "watchdog%d", wdd->id);
910 if (IS_ERR(dev)) {
911 watchdog_cdev_unregister(wdd);
912 return PTR_ERR(dev);
913 }
914
915 return ret;
916}
917
918/*
919 * watchdog_dev_unregister: unregister a watchdog device
920 * @watchdog: watchdog device
921 *
922 * Unregister watchdog device and if needed the legacy
923 * /dev/watchdog device.
924 */
925
926void watchdog_dev_unregister(struct watchdog_device *wdd)
927{
928 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
929 watchdog_cdev_unregister(wdd);
930}
931
932/*
933 * watchdog_dev_init: init dev part of watchdog core
934 *
935 * Allocate a range of chardev nodes to use for watchdog devices
936 */
937
938int __init watchdog_dev_init(void)
939{
940 int err;
941
942 watchdog_wq = alloc_workqueue("watchdogd",
943 WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
944 if (!watchdog_wq) {
945 pr_err("Failed to create watchdog workqueue\n");
946 return -ENOMEM;
947 }
948
949 err = class_register(&watchdog_class);
950 if (err < 0) {
951 pr_err("couldn't register class\n");
952 return err;
953 }
954
955 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
956 if (err < 0) {
957 pr_err("watchdog: unable to allocate char dev region\n");
958 class_unregister(&watchdog_class);
959 return err;
960 }
961
962 return 0;
963}
964
965/*
966 * watchdog_dev_exit: exit dev part of watchdog core
967 *
968 * Release the range of chardev nodes used for watchdog devices
969 */
970
971void __exit watchdog_dev_exit(void)
972{
973 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
974 class_unregister(&watchdog_class);
975 destroy_workqueue(watchdog_wq);
976}