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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * watchdog_dev.c
4 *
5 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
6 * All Rights Reserved.
7 *
8 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
9 *
10 * (c) Copyright 2021 Hewlett Packard Enterprise Development LP.
11 *
12 * This source code is part of the generic code that can be used
13 * by all the watchdog timer drivers.
14 *
15 * This part of the generic code takes care of the following
16 * misc device: /dev/watchdog.
17 *
18 * Based on source code of the following authors:
19 * Matt Domsch <Matt_Domsch@dell.com>,
20 * Rob Radez <rob@osinvestor.com>,
21 * Rusty Lynch <rusty@linux.co.intel.com>
22 * Satyam Sharma <satyam@infradead.org>
23 * Randy Dunlap <randy.dunlap@oracle.com>
24 *
25 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
26 * admit liability nor provide warranty for any of this software.
27 * This material is provided "AS-IS" and at no charge.
28 */
29
30#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31
32#include <linux/cdev.h> /* For character device */
33#include <linux/errno.h> /* For the -ENODEV/... values */
34#include <linux/fs.h> /* For file operations */
35#include <linux/init.h> /* For __init/__exit/... */
36#include <linux/hrtimer.h> /* For hrtimers */
37#include <linux/kernel.h> /* For printk/panic/... */
38#include <linux/kthread.h> /* For kthread_work */
39#include <linux/miscdevice.h> /* For handling misc devices */
40#include <linux/module.h> /* For module stuff/... */
41#include <linux/mutex.h> /* For mutexes */
42#include <linux/slab.h> /* For memory functions */
43#include <linux/types.h> /* For standard types (like size_t) */
44#include <linux/watchdog.h> /* For watchdog specific items */
45#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
46
47#include "watchdog_core.h"
48#include "watchdog_pretimeout.h"
49
50#include <trace/events/watchdog.h>
51
52/* the dev_t structure to store the dynamically allocated watchdog devices */
53static dev_t watchdog_devt;
54/* Reference to watchdog device behind /dev/watchdog */
55static struct watchdog_core_data *old_wd_data;
56
57static struct kthread_worker *watchdog_kworker;
58
59static bool handle_boot_enabled =
60 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
61
62static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
63
64static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
65{
66 return ktime_after(ktime_get(), data->open_deadline);
67}
68
69static void watchdog_set_open_deadline(struct watchdog_core_data *data)
70{
71 data->open_deadline = open_timeout ?
72 ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;
73}
74
75static inline bool watchdog_need_worker(struct watchdog_device *wdd)
76{
77 /* All variables in milli-seconds */
78 unsigned int hm = wdd->max_hw_heartbeat_ms;
79 unsigned int t = wdd->timeout * 1000;
80
81 /*
82 * A worker to generate heartbeat requests is needed if all of the
83 * following conditions are true.
84 * - Userspace activated the watchdog.
85 * - The driver provided a value for the maximum hardware timeout, and
86 * thus is aware that the framework supports generating heartbeat
87 * requests.
88 * - Userspace requests a longer timeout than the hardware can handle.
89 *
90 * Alternatively, if userspace has not opened the watchdog
91 * device, we take care of feeding the watchdog if it is
92 * running.
93 */
94 return (hm && watchdog_active(wdd) && t > hm) ||
95 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
96}
97
98static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
99{
100 struct watchdog_core_data *wd_data = wdd->wd_data;
101 unsigned int timeout_ms = wdd->timeout * 1000;
102 ktime_t keepalive_interval;
103 ktime_t last_heartbeat, latest_heartbeat;
104 ktime_t virt_timeout;
105 unsigned int hw_heartbeat_ms;
106
107 if (watchdog_active(wdd))
108 virt_timeout = ktime_add(wd_data->last_keepalive,
109 ms_to_ktime(timeout_ms));
110 else
111 virt_timeout = wd_data->open_deadline;
112
113 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
114 keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
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 = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
122 latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
123 if (ktime_before(latest_heartbeat, keepalive_interval))
124 return latest_heartbeat;
125 return keepalive_interval;
126}
127
128static inline void watchdog_update_worker(struct watchdog_device *wdd)
129{
130 struct watchdog_core_data *wd_data = wdd->wd_data;
131
132 if (watchdog_need_worker(wdd)) {
133 ktime_t t = watchdog_next_keepalive(wdd);
134
135 if (t > 0)
136 hrtimer_start(&wd_data->timer, t,
137 HRTIMER_MODE_REL_HARD);
138 } else {
139 hrtimer_cancel(&wd_data->timer);
140 }
141}
142
143static int __watchdog_ping(struct watchdog_device *wdd)
144{
145 struct watchdog_core_data *wd_data = wdd->wd_data;
146 ktime_t earliest_keepalive, now;
147 int err;
148
149 earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
150 ms_to_ktime(wdd->min_hw_heartbeat_ms));
151 now = ktime_get();
152
153 if (ktime_after(earliest_keepalive, now)) {
154 hrtimer_start(&wd_data->timer,
155 ktime_sub(earliest_keepalive, now),
156 HRTIMER_MODE_REL_HARD);
157 return 0;
158 }
159
160 wd_data->last_hw_keepalive = now;
161
162 if (wdd->ops->ping) {
163 err = wdd->ops->ping(wdd); /* ping the watchdog */
164 trace_watchdog_ping(wdd, err);
165 } else {
166 err = wdd->ops->start(wdd); /* restart watchdog */
167 trace_watchdog_start(wdd, err);
168 }
169
170 if (err == 0)
171 watchdog_hrtimer_pretimeout_start(wdd);
172
173 watchdog_update_worker(wdd);
174
175 return err;
176}
177
178/*
179 * watchdog_ping - ping the watchdog
180 * @wdd: The watchdog device to ping
181 *
182 * If the watchdog has no own ping operation then it needs to be
183 * restarted via the start operation. This wrapper function does
184 * exactly that.
185 * We only ping when the watchdog device is running.
186 * The caller must hold wd_data->lock.
187 *
188 * Return: 0 on success, error otherwise.
189 */
190static int watchdog_ping(struct watchdog_device *wdd)
191{
192 struct watchdog_core_data *wd_data = wdd->wd_data;
193
194 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
195 return 0;
196
197 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
198
199 wd_data->last_keepalive = ktime_get();
200 return __watchdog_ping(wdd);
201}
202
203static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
204{
205 struct watchdog_device *wdd = wd_data->wdd;
206
207 if (!wdd)
208 return false;
209
210 if (watchdog_active(wdd))
211 return true;
212
213 return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);
214}
215
216static void watchdog_ping_work(struct kthread_work *work)
217{
218 struct watchdog_core_data *wd_data;
219
220 wd_data = container_of(work, struct watchdog_core_data, work);
221
222 mutex_lock(&wd_data->lock);
223 if (watchdog_worker_should_ping(wd_data))
224 __watchdog_ping(wd_data->wdd);
225 mutex_unlock(&wd_data->lock);
226}
227
228static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
229{
230 struct watchdog_core_data *wd_data;
231
232 wd_data = container_of(timer, struct watchdog_core_data, timer);
233
234 kthread_queue_work(watchdog_kworker, &wd_data->work);
235 return HRTIMER_NORESTART;
236}
237
238/*
239 * watchdog_start - wrapper to start the watchdog
240 * @wdd: The watchdog device to start
241 *
242 * Start the watchdog if it is not active and mark it active.
243 * The caller must hold wd_data->lock.
244 *
245 * Return: 0 on success or a negative errno code for failure.
246 */
247static int watchdog_start(struct watchdog_device *wdd)
248{
249 struct watchdog_core_data *wd_data = wdd->wd_data;
250 ktime_t started_at;
251 int err;
252
253 if (watchdog_active(wdd))
254 return 0;
255
256 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
257
258 started_at = ktime_get();
259 if (watchdog_hw_running(wdd) && wdd->ops->ping) {
260 err = __watchdog_ping(wdd);
261 if (err == 0) {
262 set_bit(WDOG_ACTIVE, &wdd->status);
263 watchdog_hrtimer_pretimeout_start(wdd);
264 }
265 } else {
266 err = wdd->ops->start(wdd);
267 trace_watchdog_start(wdd, err);
268 if (err == 0) {
269 set_bit(WDOG_ACTIVE, &wdd->status);
270 wd_data->last_keepalive = started_at;
271 wd_data->last_hw_keepalive = started_at;
272 watchdog_update_worker(wdd);
273 watchdog_hrtimer_pretimeout_start(wdd);
274 }
275 }
276
277 return err;
278}
279
280/*
281 * watchdog_stop - wrapper to stop the watchdog
282 * @wdd: The watchdog device to stop
283 *
284 * Stop the watchdog if it is still active and unmark it active.
285 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
286 * The caller must hold wd_data->lock.
287 *
288 * Return: 0 on success or a negative errno code for failure.
289 */
290static int watchdog_stop(struct watchdog_device *wdd)
291{
292 int err = 0;
293
294 if (!watchdog_active(wdd))
295 return 0;
296
297 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
298 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
299 wdd->id);
300 return -EBUSY;
301 }
302
303 if (wdd->ops->stop) {
304 clear_bit(WDOG_HW_RUNNING, &wdd->status);
305 err = wdd->ops->stop(wdd);
306 trace_watchdog_stop(wdd, err);
307 } else {
308 set_bit(WDOG_HW_RUNNING, &wdd->status);
309 }
310
311 if (err == 0) {
312 clear_bit(WDOG_ACTIVE, &wdd->status);
313 watchdog_update_worker(wdd);
314 watchdog_hrtimer_pretimeout_stop(wdd);
315 }
316
317 return err;
318}
319
320/*
321 * watchdog_get_status - wrapper to get the watchdog status
322 * @wdd: The watchdog device to get the status from
323 *
324 * Get the watchdog's status flags.
325 * The caller must hold wd_data->lock.
326 *
327 * Return: watchdog's status flags.
328 */
329static unsigned int watchdog_get_status(struct watchdog_device *wdd)
330{
331 struct watchdog_core_data *wd_data = wdd->wd_data;
332 unsigned int status;
333
334 if (wdd->ops->status)
335 status = wdd->ops->status(wdd);
336 else
337 status = wdd->bootstatus & (WDIOF_CARDRESET |
338 WDIOF_OVERHEAT |
339 WDIOF_FANFAULT |
340 WDIOF_EXTERN1 |
341 WDIOF_EXTERN2 |
342 WDIOF_POWERUNDER |
343 WDIOF_POWEROVER);
344
345 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
346 status |= WDIOF_MAGICCLOSE;
347
348 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
349 status |= WDIOF_KEEPALIVEPING;
350
351 if (IS_ENABLED(CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT))
352 status |= WDIOF_PRETIMEOUT;
353
354 return status;
355}
356
357/*
358 * watchdog_set_timeout - set the watchdog timer timeout
359 * @wdd: The watchdog device to set the timeout for
360 * @timeout: Timeout to set in seconds
361 *
362 * The caller must hold wd_data->lock.
363 *
364 * Return: 0 if successful, error otherwise.
365 */
366static int watchdog_set_timeout(struct watchdog_device *wdd,
367 unsigned int timeout)
368{
369 int err = 0;
370
371 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
372 return -EOPNOTSUPP;
373
374 if (watchdog_timeout_invalid(wdd, timeout))
375 return -EINVAL;
376
377 if (wdd->ops->set_timeout) {
378 err = wdd->ops->set_timeout(wdd, timeout);
379 trace_watchdog_set_timeout(wdd, timeout, err);
380 } else {
381 wdd->timeout = timeout;
382 /* Disable pretimeout if it doesn't fit the new timeout */
383 if (wdd->pretimeout >= wdd->timeout)
384 wdd->pretimeout = 0;
385 }
386
387 watchdog_update_worker(wdd);
388
389 return err;
390}
391
392/*
393 * watchdog_set_pretimeout - set the watchdog timer pretimeout
394 * @wdd: The watchdog device to set the timeout for
395 * @timeout: pretimeout to set in seconds
396 *
397 * Return: 0 if successful, error otherwise.
398 */
399static int watchdog_set_pretimeout(struct watchdog_device *wdd,
400 unsigned int timeout)
401{
402 int err = 0;
403
404 if (!watchdog_have_pretimeout(wdd))
405 return -EOPNOTSUPP;
406
407 if (watchdog_pretimeout_invalid(wdd, timeout))
408 return -EINVAL;
409
410 if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
411 err = wdd->ops->set_pretimeout(wdd, timeout);
412 else
413 wdd->pretimeout = timeout;
414
415 return err;
416}
417
418/*
419 * watchdog_get_timeleft - wrapper to get the time left before a reboot
420 * @wdd: The watchdog device to get the remaining time from
421 * @timeleft: The time that's left
422 *
423 * Get the time before a watchdog will reboot (if not pinged).
424 * The caller must hold wd_data->lock.
425 *
426 * Return: 0 if successful, error otherwise.
427 */
428static int watchdog_get_timeleft(struct watchdog_device *wdd,
429 unsigned int *timeleft)
430{
431 *timeleft = 0;
432
433 if (!wdd->ops->get_timeleft)
434 return -EOPNOTSUPP;
435
436 *timeleft = wdd->ops->get_timeleft(wdd);
437
438 return 0;
439}
440
441#ifdef CONFIG_WATCHDOG_SYSFS
442static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
443 char *buf)
444{
445 struct watchdog_device *wdd = dev_get_drvdata(dev);
446
447 return sysfs_emit(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT,
448 &wdd->status));
449}
450
451static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,
452 const char *buf, size_t len)
453{
454 struct watchdog_device *wdd = dev_get_drvdata(dev);
455 unsigned int value;
456 int ret;
457
458 ret = kstrtouint(buf, 0, &value);
459 if (ret)
460 return ret;
461 if (value > 1)
462 return -EINVAL;
463 /* nowayout cannot be disabled once set */
464 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)
465 return -EPERM;
466 watchdog_set_nowayout(wdd, value);
467 return len;
468}
469static DEVICE_ATTR_RW(nowayout);
470
471static ssize_t status_show(struct device *dev, struct device_attribute *attr,
472 char *buf)
473{
474 struct watchdog_device *wdd = dev_get_drvdata(dev);
475 struct watchdog_core_data *wd_data = wdd->wd_data;
476 unsigned int status;
477
478 mutex_lock(&wd_data->lock);
479 status = watchdog_get_status(wdd);
480 mutex_unlock(&wd_data->lock);
481
482 return sysfs_emit(buf, "0x%x\n", status);
483}
484static DEVICE_ATTR_RO(status);
485
486static ssize_t bootstatus_show(struct device *dev,
487 struct device_attribute *attr, char *buf)
488{
489 struct watchdog_device *wdd = dev_get_drvdata(dev);
490
491 return sysfs_emit(buf, "%u\n", wdd->bootstatus);
492}
493static DEVICE_ATTR_RO(bootstatus);
494
495static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
496 char *buf)
497{
498 struct watchdog_device *wdd = dev_get_drvdata(dev);
499 struct watchdog_core_data *wd_data = wdd->wd_data;
500 ssize_t status;
501 unsigned int val;
502
503 mutex_lock(&wd_data->lock);
504 status = watchdog_get_timeleft(wdd, &val);
505 mutex_unlock(&wd_data->lock);
506 if (!status)
507 status = sysfs_emit(buf, "%u\n", val);
508
509 return status;
510}
511static DEVICE_ATTR_RO(timeleft);
512
513static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
514 char *buf)
515{
516 struct watchdog_device *wdd = dev_get_drvdata(dev);
517
518 return sysfs_emit(buf, "%u\n", wdd->timeout);
519}
520static DEVICE_ATTR_RO(timeout);
521
522static ssize_t min_timeout_show(struct device *dev,
523 struct device_attribute *attr, char *buf)
524{
525 struct watchdog_device *wdd = dev_get_drvdata(dev);
526
527 return sysfs_emit(buf, "%u\n", wdd->min_timeout);
528}
529static DEVICE_ATTR_RO(min_timeout);
530
531static ssize_t max_timeout_show(struct device *dev,
532 struct device_attribute *attr, char *buf)
533{
534 struct watchdog_device *wdd = dev_get_drvdata(dev);
535
536 return sysfs_emit(buf, "%u\n", wdd->max_timeout);
537}
538static DEVICE_ATTR_RO(max_timeout);
539
540static ssize_t pretimeout_show(struct device *dev,
541 struct device_attribute *attr, char *buf)
542{
543 struct watchdog_device *wdd = dev_get_drvdata(dev);
544
545 return sysfs_emit(buf, "%u\n", wdd->pretimeout);
546}
547static DEVICE_ATTR_RO(pretimeout);
548
549static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
550 char *buf)
551{
552 struct watchdog_device *wdd = dev_get_drvdata(dev);
553
554 return sysfs_emit(buf, "%s\n", wdd->info->identity);
555}
556static DEVICE_ATTR_RO(identity);
557
558static ssize_t state_show(struct device *dev, struct device_attribute *attr,
559 char *buf)
560{
561 struct watchdog_device *wdd = dev_get_drvdata(dev);
562
563 if (watchdog_active(wdd))
564 return sysfs_emit(buf, "active\n");
565
566 return sysfs_emit(buf, "inactive\n");
567}
568static DEVICE_ATTR_RO(state);
569
570static ssize_t pretimeout_available_governors_show(struct device *dev,
571 struct device_attribute *attr, char *buf)
572{
573 return watchdog_pretimeout_available_governors_get(buf);
574}
575static DEVICE_ATTR_RO(pretimeout_available_governors);
576
577static ssize_t pretimeout_governor_show(struct device *dev,
578 struct device_attribute *attr,
579 char *buf)
580{
581 struct watchdog_device *wdd = dev_get_drvdata(dev);
582
583 return watchdog_pretimeout_governor_get(wdd, buf);
584}
585
586static ssize_t pretimeout_governor_store(struct device *dev,
587 struct device_attribute *attr,
588 const char *buf, size_t count)
589{
590 struct watchdog_device *wdd = dev_get_drvdata(dev);
591 int ret = watchdog_pretimeout_governor_set(wdd, buf);
592
593 if (!ret)
594 ret = count;
595
596 return ret;
597}
598static DEVICE_ATTR_RW(pretimeout_governor);
599
600static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
601 int n)
602{
603 struct device *dev = kobj_to_dev(kobj);
604 struct watchdog_device *wdd = dev_get_drvdata(dev);
605 umode_t mode = attr->mode;
606
607 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
608 mode = 0;
609 else if (attr == &dev_attr_pretimeout.attr && !watchdog_have_pretimeout(wdd))
610 mode = 0;
611 else if ((attr == &dev_attr_pretimeout_governor.attr ||
612 attr == &dev_attr_pretimeout_available_governors.attr) &&
613 (!watchdog_have_pretimeout(wdd) || !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
614 mode = 0;
615
616 return mode;
617}
618static struct attribute *wdt_attrs[] = {
619 &dev_attr_state.attr,
620 &dev_attr_identity.attr,
621 &dev_attr_timeout.attr,
622 &dev_attr_min_timeout.attr,
623 &dev_attr_max_timeout.attr,
624 &dev_attr_pretimeout.attr,
625 &dev_attr_timeleft.attr,
626 &dev_attr_bootstatus.attr,
627 &dev_attr_status.attr,
628 &dev_attr_nowayout.attr,
629 &dev_attr_pretimeout_governor.attr,
630 &dev_attr_pretimeout_available_governors.attr,
631 NULL,
632};
633
634static const struct attribute_group wdt_group = {
635 .attrs = wdt_attrs,
636 .is_visible = wdt_is_visible,
637};
638__ATTRIBUTE_GROUPS(wdt);
639#else
640#define wdt_groups NULL
641#endif
642
643/*
644 * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
645 * @wdd: The watchdog device to do the ioctl on
646 * @cmd: Watchdog command
647 * @arg: Argument pointer
648 *
649 * The caller must hold wd_data->lock.
650 *
651 * Return: 0 if successful, error otherwise.
652 */
653static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
654 unsigned long arg)
655{
656 if (!wdd->ops->ioctl)
657 return -ENOIOCTLCMD;
658
659 return wdd->ops->ioctl(wdd, cmd, arg);
660}
661
662/*
663 * watchdog_write - writes to the watchdog
664 * @file: File from VFS
665 * @data: User address of data
666 * @len: Length of data
667 * @ppos: Pointer to the file offset
668 *
669 * A write to a watchdog device is defined as a keepalive ping.
670 * Writing the magic 'V' sequence allows the next close to turn
671 * off the watchdog (if 'nowayout' is not set).
672 *
673 * Return: @len if successful, error otherwise.
674 */
675static ssize_t watchdog_write(struct file *file, const char __user *data,
676 size_t len, loff_t *ppos)
677{
678 struct watchdog_core_data *wd_data = file->private_data;
679 struct watchdog_device *wdd;
680 int err;
681 size_t i;
682 char c;
683
684 if (len == 0)
685 return 0;
686
687 /*
688 * Note: just in case someone wrote the magic character
689 * five months ago...
690 */
691 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
692
693 /* scan to see whether or not we got the magic character */
694 for (i = 0; i != len; i++) {
695 if (get_user(c, data + i))
696 return -EFAULT;
697 if (c == 'V')
698 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
699 }
700
701 /* someone wrote to us, so we send the watchdog a keepalive ping */
702
703 err = -ENODEV;
704 mutex_lock(&wd_data->lock);
705 wdd = wd_data->wdd;
706 if (wdd)
707 err = watchdog_ping(wdd);
708 mutex_unlock(&wd_data->lock);
709
710 if (err < 0)
711 return err;
712
713 return len;
714}
715
716/*
717 * watchdog_ioctl - handle the different ioctl's for the watchdog device
718 * @file: File handle to the device
719 * @cmd: Watchdog command
720 * @arg: Argument pointer
721 *
722 * The watchdog API defines a common set of functions for all watchdogs
723 * according to their available features.
724 *
725 * Return: 0 if successful, error otherwise.
726 */
727
728static long watchdog_ioctl(struct file *file, unsigned int cmd,
729 unsigned long arg)
730{
731 struct watchdog_core_data *wd_data = file->private_data;
732 void __user *argp = (void __user *)arg;
733 struct watchdog_device *wdd;
734 int __user *p = argp;
735 unsigned int val;
736 int err;
737
738 mutex_lock(&wd_data->lock);
739
740 wdd = wd_data->wdd;
741 if (!wdd) {
742 err = -ENODEV;
743 goto out_ioctl;
744 }
745
746 err = watchdog_ioctl_op(wdd, cmd, arg);
747 if (err != -ENOIOCTLCMD)
748 goto out_ioctl;
749
750 switch (cmd) {
751 case WDIOC_GETSUPPORT:
752 err = copy_to_user(argp, wdd->info,
753 sizeof(struct watchdog_info)) ? -EFAULT : 0;
754 break;
755 case WDIOC_GETSTATUS:
756 val = watchdog_get_status(wdd);
757 err = put_user(val, p);
758 break;
759 case WDIOC_GETBOOTSTATUS:
760 err = put_user(wdd->bootstatus, p);
761 break;
762 case WDIOC_SETOPTIONS:
763 if (get_user(val, p)) {
764 err = -EFAULT;
765 break;
766 }
767 if (val & WDIOS_DISABLECARD) {
768 err = watchdog_stop(wdd);
769 if (err < 0)
770 break;
771 }
772 if (val & WDIOS_ENABLECARD)
773 err = watchdog_start(wdd);
774 break;
775 case WDIOC_KEEPALIVE:
776 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
777 err = -EOPNOTSUPP;
778 break;
779 }
780 err = watchdog_ping(wdd);
781 break;
782 case WDIOC_SETTIMEOUT:
783 if (get_user(val, p)) {
784 err = -EFAULT;
785 break;
786 }
787 err = watchdog_set_timeout(wdd, val);
788 if (err < 0)
789 break;
790 /* If the watchdog is active then we send a keepalive ping
791 * to make sure that the watchdog keep's running (and if
792 * possible that it takes the new timeout) */
793 err = watchdog_ping(wdd);
794 if (err < 0)
795 break;
796 fallthrough;
797 case WDIOC_GETTIMEOUT:
798 /* timeout == 0 means that we don't know the timeout */
799 if (wdd->timeout == 0) {
800 err = -EOPNOTSUPP;
801 break;
802 }
803 err = put_user(wdd->timeout, p);
804 break;
805 case WDIOC_GETTIMELEFT:
806 err = watchdog_get_timeleft(wdd, &val);
807 if (err < 0)
808 break;
809 err = put_user(val, p);
810 break;
811 case WDIOC_SETPRETIMEOUT:
812 if (get_user(val, p)) {
813 err = -EFAULT;
814 break;
815 }
816 err = watchdog_set_pretimeout(wdd, val);
817 break;
818 case WDIOC_GETPRETIMEOUT:
819 err = put_user(wdd->pretimeout, p);
820 break;
821 default:
822 err = -ENOTTY;
823 break;
824 }
825
826out_ioctl:
827 mutex_unlock(&wd_data->lock);
828 return err;
829}
830
831/*
832 * watchdog_open - open the /dev/watchdog* devices
833 * @inode: Inode of device
834 * @file: File handle to device
835 *
836 * When the /dev/watchdog* device gets opened, we start the watchdog.
837 * Watch out: the /dev/watchdog device is single open, so we make sure
838 * it can only be opened once.
839 *
840 * Return: 0 if successful, error otherwise.
841 */
842static int watchdog_open(struct inode *inode, struct file *file)
843{
844 struct watchdog_core_data *wd_data;
845 struct watchdog_device *wdd;
846 bool hw_running;
847 int err;
848
849 /* Get the corresponding watchdog device */
850 if (imajor(inode) == MISC_MAJOR)
851 wd_data = old_wd_data;
852 else
853 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
854 cdev);
855
856 /* the watchdog is single open! */
857 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
858 return -EBUSY;
859
860 wdd = wd_data->wdd;
861
862 /*
863 * If the /dev/watchdog device is open, we don't want the module
864 * to be unloaded.
865 */
866 hw_running = watchdog_hw_running(wdd);
867 if (!hw_running && !try_module_get(wdd->ops->owner)) {
868 err = -EBUSY;
869 goto out_clear;
870 }
871
872 err = watchdog_start(wdd);
873 if (err < 0)
874 goto out_mod;
875
876 file->private_data = wd_data;
877
878 if (!hw_running)
879 get_device(&wd_data->dev);
880
881 /*
882 * open_timeout only applies for the first open from
883 * userspace. Set open_deadline to infinity so that the kernel
884 * will take care of an always-running hardware watchdog in
885 * case the device gets magic-closed or WDIOS_DISABLECARD is
886 * applied.
887 */
888 wd_data->open_deadline = KTIME_MAX;
889
890 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
891 return stream_open(inode, file);
892
893out_mod:
894 module_put(wd_data->wdd->ops->owner);
895out_clear:
896 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
897 return err;
898}
899
900static void watchdog_core_data_release(struct device *dev)
901{
902 struct watchdog_core_data *wd_data;
903
904 wd_data = container_of(dev, struct watchdog_core_data, dev);
905
906 kfree(wd_data);
907}
908
909/*
910 * watchdog_release - release the watchdog device
911 * @inode: Inode of device
912 * @file: File handle to device
913 *
914 * This is the code for when /dev/watchdog gets closed. We will only
915 * stop the watchdog when we have received the magic char (and nowayout
916 * was not set), else the watchdog will keep running.
917 *
918 * Always returns 0.
919 */
920static int watchdog_release(struct inode *inode, struct file *file)
921{
922 struct watchdog_core_data *wd_data = file->private_data;
923 struct watchdog_device *wdd;
924 int err = -EBUSY;
925 bool running;
926
927 mutex_lock(&wd_data->lock);
928
929 wdd = wd_data->wdd;
930 if (!wdd)
931 goto done;
932
933 /*
934 * We only stop the watchdog if we received the magic character
935 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
936 * watchdog_stop will fail.
937 */
938 if (!watchdog_active(wdd))
939 err = 0;
940 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
941 !(wdd->info->options & WDIOF_MAGICCLOSE))
942 err = watchdog_stop(wdd);
943
944 /* If the watchdog was not stopped, send a keepalive ping */
945 if (err < 0) {
946 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
947 watchdog_ping(wdd);
948 }
949
950 watchdog_update_worker(wdd);
951
952 /* make sure that /dev/watchdog can be re-opened */
953 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
954
955done:
956 running = wdd && watchdog_hw_running(wdd);
957 mutex_unlock(&wd_data->lock);
958 /*
959 * Allow the owner module to be unloaded again unless the watchdog
960 * is still running. If the watchdog is still running, it can not
961 * be stopped, and its driver must not be unloaded.
962 */
963 if (!running) {
964 module_put(wd_data->cdev.owner);
965 put_device(&wd_data->dev);
966 }
967 return 0;
968}
969
970static const struct file_operations watchdog_fops = {
971 .owner = THIS_MODULE,
972 .write = watchdog_write,
973 .unlocked_ioctl = watchdog_ioctl,
974 .compat_ioctl = compat_ptr_ioctl,
975 .open = watchdog_open,
976 .release = watchdog_release,
977};
978
979static struct miscdevice watchdog_miscdev = {
980 .minor = WATCHDOG_MINOR,
981 .name = "watchdog",
982 .fops = &watchdog_fops,
983};
984
985static struct class watchdog_class = {
986 .name = "watchdog",
987 .owner = THIS_MODULE,
988 .dev_groups = wdt_groups,
989};
990
991/*
992 * watchdog_cdev_register - register watchdog character device
993 * @wdd: Watchdog device
994 *
995 * Register a watchdog character device including handling the legacy
996 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
997 * thus we set it up like that.
998 *
999 * Return: 0 if successful, error otherwise.
1000 */
1001static int watchdog_cdev_register(struct watchdog_device *wdd)
1002{
1003 struct watchdog_core_data *wd_data;
1004 int err;
1005
1006 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
1007 if (!wd_data)
1008 return -ENOMEM;
1009 mutex_init(&wd_data->lock);
1010
1011 wd_data->wdd = wdd;
1012 wdd->wd_data = wd_data;
1013
1014 if (IS_ERR_OR_NULL(watchdog_kworker)) {
1015 kfree(wd_data);
1016 return -ENODEV;
1017 }
1018
1019 device_initialize(&wd_data->dev);
1020 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
1021 wd_data->dev.class = &watchdog_class;
1022 wd_data->dev.parent = wdd->parent;
1023 wd_data->dev.groups = wdd->groups;
1024 wd_data->dev.release = watchdog_core_data_release;
1025 dev_set_drvdata(&wd_data->dev, wdd);
1026 err = dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
1027 if (err) {
1028 put_device(&wd_data->dev);
1029 return err;
1030 }
1031
1032 kthread_init_work(&wd_data->work, watchdog_ping_work);
1033 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1034 wd_data->timer.function = watchdog_timer_expired;
1035 watchdog_hrtimer_pretimeout_init(wdd);
1036
1037 if (wdd->id == 0) {
1038 old_wd_data = wd_data;
1039 watchdog_miscdev.parent = wdd->parent;
1040 err = misc_register(&watchdog_miscdev);
1041 if (err != 0) {
1042 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
1043 wdd->info->identity, WATCHDOG_MINOR, err);
1044 if (err == -EBUSY)
1045 pr_err("%s: a legacy watchdog module is probably present.\n",
1046 wdd->info->identity);
1047 old_wd_data = NULL;
1048 put_device(&wd_data->dev);
1049 return err;
1050 }
1051 }
1052
1053 /* Fill in the data structures */
1054 cdev_init(&wd_data->cdev, &watchdog_fops);
1055
1056 /* Add the device */
1057 err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
1058 if (err) {
1059 pr_err("watchdog%d unable to add device %d:%d\n",
1060 wdd->id, MAJOR(watchdog_devt), wdd->id);
1061 if (wdd->id == 0) {
1062 misc_deregister(&watchdog_miscdev);
1063 old_wd_data = NULL;
1064 put_device(&wd_data->dev);
1065 }
1066 return err;
1067 }
1068
1069 wd_data->cdev.owner = wdd->ops->owner;
1070
1071 /* Record time of most recent heartbeat as 'just before now'. */
1072 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
1073 watchdog_set_open_deadline(wd_data);
1074
1075 /*
1076 * If the watchdog is running, prevent its driver from being unloaded,
1077 * and schedule an immediate ping.
1078 */
1079 if (watchdog_hw_running(wdd)) {
1080 __module_get(wdd->ops->owner);
1081 get_device(&wd_data->dev);
1082 if (handle_boot_enabled)
1083 hrtimer_start(&wd_data->timer, 0,
1084 HRTIMER_MODE_REL_HARD);
1085 else
1086 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
1087 wdd->id);
1088 }
1089
1090 return 0;
1091}
1092
1093/*
1094 * watchdog_cdev_unregister - unregister watchdog character device
1095 * @wdd: Watchdog device
1096 *
1097 * Unregister watchdog character device and if needed the legacy
1098 * /dev/watchdog device.
1099 */
1100static void watchdog_cdev_unregister(struct watchdog_device *wdd)
1101{
1102 struct watchdog_core_data *wd_data = wdd->wd_data;
1103
1104 cdev_device_del(&wd_data->cdev, &wd_data->dev);
1105 if (wdd->id == 0) {
1106 misc_deregister(&watchdog_miscdev);
1107 old_wd_data = NULL;
1108 }
1109
1110 if (watchdog_active(wdd) &&
1111 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
1112 watchdog_stop(wdd);
1113 }
1114
1115 watchdog_hrtimer_pretimeout_stop(wdd);
1116
1117 mutex_lock(&wd_data->lock);
1118 wd_data->wdd = NULL;
1119 wdd->wd_data = NULL;
1120 mutex_unlock(&wd_data->lock);
1121
1122 hrtimer_cancel(&wd_data->timer);
1123 kthread_cancel_work_sync(&wd_data->work);
1124
1125 put_device(&wd_data->dev);
1126}
1127
1128/**
1129 * watchdog_dev_register - register a watchdog device
1130 * @wdd: Watchdog device
1131 *
1132 * Register a watchdog device including handling the legacy
1133 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1134 * thus we set it up like that.
1135 *
1136 * Return: 0 if successful, error otherwise.
1137 */
1138int watchdog_dev_register(struct watchdog_device *wdd)
1139{
1140 int ret;
1141
1142 ret = watchdog_cdev_register(wdd);
1143 if (ret)
1144 return ret;
1145
1146 ret = watchdog_register_pretimeout(wdd);
1147 if (ret)
1148 watchdog_cdev_unregister(wdd);
1149
1150 return ret;
1151}
1152
1153/**
1154 * watchdog_dev_unregister - unregister a watchdog device
1155 * @wdd: watchdog device
1156 *
1157 * Unregister watchdog device and if needed the legacy
1158 * /dev/watchdog device.
1159 */
1160void watchdog_dev_unregister(struct watchdog_device *wdd)
1161{
1162 watchdog_unregister_pretimeout(wdd);
1163 watchdog_cdev_unregister(wdd);
1164}
1165
1166/**
1167 * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
1168 * @wdd: Watchdog device
1169 * @last_ping_ms: Time since last HW heartbeat
1170 *
1171 * Adjusts the last known HW keepalive time for a watchdog timer.
1172 * This is needed if the watchdog is already running when the probe
1173 * function is called, and it can't be pinged immediately. This
1174 * function must be called immediately after watchdog registration,
1175 * and min_hw_heartbeat_ms must be set for this to be useful.
1176 *
1177 * Return: 0 if successful, error otherwise.
1178 */
1179int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
1180 unsigned int last_ping_ms)
1181{
1182 struct watchdog_core_data *wd_data;
1183 ktime_t now;
1184
1185 if (!wdd)
1186 return -EINVAL;
1187
1188 wd_data = wdd->wd_data;
1189
1190 now = ktime_get();
1191
1192 wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
1193
1194 if (watchdog_hw_running(wdd) && handle_boot_enabled)
1195 return __watchdog_ping(wdd);
1196
1197 return 0;
1198}
1199EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
1200
1201/**
1202 * watchdog_dev_init - init dev part of watchdog core
1203 *
1204 * Allocate a range of chardev nodes to use for watchdog devices.
1205 *
1206 * Return: 0 if successful, error otherwise.
1207 */
1208int __init watchdog_dev_init(void)
1209{
1210 int err;
1211
1212 watchdog_kworker = kthread_create_worker(0, "watchdogd");
1213 if (IS_ERR(watchdog_kworker)) {
1214 pr_err("Failed to create watchdog kworker\n");
1215 return PTR_ERR(watchdog_kworker);
1216 }
1217 sched_set_fifo(watchdog_kworker->task);
1218
1219 err = class_register(&watchdog_class);
1220 if (err < 0) {
1221 pr_err("couldn't register class\n");
1222 goto err_register;
1223 }
1224
1225 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1226 if (err < 0) {
1227 pr_err("watchdog: unable to allocate char dev region\n");
1228 goto err_alloc;
1229 }
1230
1231 return 0;
1232
1233err_alloc:
1234 class_unregister(&watchdog_class);
1235err_register:
1236 kthread_destroy_worker(watchdog_kworker);
1237 return err;
1238}
1239
1240/**
1241 * watchdog_dev_exit - exit dev part of watchdog core
1242 *
1243 * Release the range of chardev nodes used for watchdog devices.
1244 */
1245void __exit watchdog_dev_exit(void)
1246{
1247 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1248 class_unregister(&watchdog_class);
1249 kthread_destroy_worker(watchdog_kworker);
1250}
1251
1252int watchdog_dev_suspend(struct watchdog_device *wdd)
1253{
1254 struct watchdog_core_data *wd_data = wdd->wd_data;
1255 int ret = 0;
1256
1257 if (!wdd->wd_data)
1258 return -ENODEV;
1259
1260 /* ping for the last time before suspend */
1261 mutex_lock(&wd_data->lock);
1262 if (watchdog_worker_should_ping(wd_data))
1263 ret = __watchdog_ping(wd_data->wdd);
1264 mutex_unlock(&wd_data->lock);
1265
1266 if (ret)
1267 return ret;
1268
1269 /*
1270 * make sure that watchdog worker will not kick in when the wdog is
1271 * suspended
1272 */
1273 hrtimer_cancel(&wd_data->timer);
1274 kthread_cancel_work_sync(&wd_data->work);
1275
1276 return 0;
1277}
1278
1279int watchdog_dev_resume(struct watchdog_device *wdd)
1280{
1281 struct watchdog_core_data *wd_data = wdd->wd_data;
1282 int ret = 0;
1283
1284 if (!wdd->wd_data)
1285 return -ENODEV;
1286
1287 /*
1288 * __watchdog_ping will also retrigger hrtimer and therefore restore the
1289 * ping worker if needed.
1290 */
1291 mutex_lock(&wd_data->lock);
1292 if (watchdog_worker_should_ping(wd_data))
1293 ret = __watchdog_ping(wd_data->wdd);
1294 mutex_unlock(&wd_data->lock);
1295
1296 return ret;
1297}
1298
1299module_param(handle_boot_enabled, bool, 0444);
1300MODULE_PARM_DESC(handle_boot_enabled,
1301 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1302 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");
1303
1304module_param(open_timeout, uint, 0644);
1305MODULE_PARM_DESC(open_timeout,
1306 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
1307 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * watchdog_dev.c
4 *
5 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
6 * All Rights Reserved.
7 *
8 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
9 *
10 *
11 * This source code is part of the generic code that can be used
12 * by all the watchdog timer drivers.
13 *
14 * This part of the generic code takes care of the following
15 * misc device: /dev/watchdog.
16 *
17 * Based on source code of the following authors:
18 * Matt Domsch <Matt_Domsch@dell.com>,
19 * Rob Radez <rob@osinvestor.com>,
20 * Rusty Lynch <rusty@linux.co.intel.com>
21 * Satyam Sharma <satyam@infradead.org>
22 * Randy Dunlap <randy.dunlap@oracle.com>
23 *
24 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
25 * admit liability nor provide warranty for any of this software.
26 * This material is provided "AS-IS" and at no charge.
27 */
28
29#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
30
31#include <linux/cdev.h> /* For character device */
32#include <linux/errno.h> /* For the -ENODEV/... values */
33#include <linux/fs.h> /* For file operations */
34#include <linux/init.h> /* For __init/__exit/... */
35#include <linux/hrtimer.h> /* For hrtimers */
36#include <linux/kernel.h> /* For printk/panic/... */
37#include <linux/kref.h> /* For data references */
38#include <linux/kthread.h> /* For kthread_work */
39#include <linux/miscdevice.h> /* For handling misc devices */
40#include <linux/module.h> /* For module stuff/... */
41#include <linux/mutex.h> /* For mutexes */
42#include <linux/reboot.h> /* For reboot notifier */
43#include <linux/slab.h> /* For memory functions */
44#include <linux/types.h> /* For standard types (like size_t) */
45#include <linux/watchdog.h> /* For watchdog specific items */
46#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
47
48#include <uapi/linux/sched/types.h> /* For struct sched_param */
49
50#include "watchdog_core.h"
51#include "watchdog_pretimeout.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 ktime_t last_keepalive;
67 ktime_t last_hw_keepalive;
68 ktime_t open_deadline;
69 struct hrtimer timer;
70 struct kthread_work work;
71 unsigned long status; /* Internal status bits */
72#define _WDOG_DEV_OPEN 0 /* Opened ? */
73#define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
74#define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
75};
76
77/* the dev_t structure to store the dynamically allocated watchdog devices */
78static dev_t watchdog_devt;
79/* Reference to watchdog device behind /dev/watchdog */
80static struct watchdog_core_data *old_wd_data;
81
82static struct kthread_worker *watchdog_kworker;
83
84static bool handle_boot_enabled =
85 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
86
87static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
88
89static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
90{
91 return ktime_after(ktime_get(), data->open_deadline);
92}
93
94static void watchdog_set_open_deadline(struct watchdog_core_data *data)
95{
96 data->open_deadline = open_timeout ?
97 ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;
98}
99
100static inline bool watchdog_need_worker(struct watchdog_device *wdd)
101{
102 /* All variables in milli-seconds */
103 unsigned int hm = wdd->max_hw_heartbeat_ms;
104 unsigned int t = wdd->timeout * 1000;
105
106 /*
107 * A worker to generate heartbeat requests is needed if all of the
108 * following conditions are true.
109 * - Userspace activated the watchdog.
110 * - The driver provided a value for the maximum hardware timeout, and
111 * thus is aware that the framework supports generating heartbeat
112 * requests.
113 * - Userspace requests a longer timeout than the hardware can handle.
114 *
115 * Alternatively, if userspace has not opened the watchdog
116 * device, we take care of feeding the watchdog if it is
117 * running.
118 */
119 return (hm && watchdog_active(wdd) && t > hm) ||
120 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
121}
122
123static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
124{
125 struct watchdog_core_data *wd_data = wdd->wd_data;
126 unsigned int timeout_ms = wdd->timeout * 1000;
127 ktime_t keepalive_interval;
128 ktime_t last_heartbeat, latest_heartbeat;
129 ktime_t virt_timeout;
130 unsigned int hw_heartbeat_ms;
131
132 if (watchdog_active(wdd))
133 virt_timeout = ktime_add(wd_data->last_keepalive,
134 ms_to_ktime(timeout_ms));
135 else
136 virt_timeout = wd_data->open_deadline;
137
138 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
139 keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
140
141 /*
142 * To ensure that the watchdog times out wdd->timeout seconds
143 * after the most recent ping from userspace, the last
144 * worker ping has to come in hw_heartbeat_ms before this timeout.
145 */
146 last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
147 latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
148 if (ktime_before(latest_heartbeat, keepalive_interval))
149 return latest_heartbeat;
150 return keepalive_interval;
151}
152
153static inline void watchdog_update_worker(struct watchdog_device *wdd)
154{
155 struct watchdog_core_data *wd_data = wdd->wd_data;
156
157 if (watchdog_need_worker(wdd)) {
158 ktime_t t = watchdog_next_keepalive(wdd);
159
160 if (t > 0)
161 hrtimer_start(&wd_data->timer, t, HRTIMER_MODE_REL);
162 } else {
163 hrtimer_cancel(&wd_data->timer);
164 }
165}
166
167static int __watchdog_ping(struct watchdog_device *wdd)
168{
169 struct watchdog_core_data *wd_data = wdd->wd_data;
170 ktime_t earliest_keepalive, now;
171 int err;
172
173 earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
174 ms_to_ktime(wdd->min_hw_heartbeat_ms));
175 now = ktime_get();
176
177 if (ktime_after(earliest_keepalive, now)) {
178 hrtimer_start(&wd_data->timer,
179 ktime_sub(earliest_keepalive, now),
180 HRTIMER_MODE_REL);
181 return 0;
182 }
183
184 wd_data->last_hw_keepalive = now;
185
186 if (wdd->ops->ping)
187 err = wdd->ops->ping(wdd); /* ping the watchdog */
188 else
189 err = wdd->ops->start(wdd); /* restart watchdog */
190
191 watchdog_update_worker(wdd);
192
193 return err;
194}
195
196/*
197 * watchdog_ping: ping the watchdog.
198 * @wdd: the watchdog device to ping
199 *
200 * The caller must hold wd_data->lock.
201 *
202 * If the watchdog has no own ping operation then it needs to be
203 * restarted via the start operation. This wrapper function does
204 * exactly that.
205 * We only ping when the watchdog device is running.
206 */
207
208static int watchdog_ping(struct watchdog_device *wdd)
209{
210 struct watchdog_core_data *wd_data = wdd->wd_data;
211
212 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
213 return 0;
214
215 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
216
217 wd_data->last_keepalive = ktime_get();
218 return __watchdog_ping(wdd);
219}
220
221static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
222{
223 struct watchdog_device *wdd = wd_data->wdd;
224
225 if (!wdd)
226 return false;
227
228 if (watchdog_active(wdd))
229 return true;
230
231 return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);
232}
233
234static void watchdog_ping_work(struct kthread_work *work)
235{
236 struct watchdog_core_data *wd_data;
237
238 wd_data = container_of(work, struct watchdog_core_data, work);
239
240 mutex_lock(&wd_data->lock);
241 if (watchdog_worker_should_ping(wd_data))
242 __watchdog_ping(wd_data->wdd);
243 mutex_unlock(&wd_data->lock);
244}
245
246static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
247{
248 struct watchdog_core_data *wd_data;
249
250 wd_data = container_of(timer, struct watchdog_core_data, timer);
251
252 kthread_queue_work(watchdog_kworker, &wd_data->work);
253 return HRTIMER_NORESTART;
254}
255
256/*
257 * watchdog_start: wrapper to start the watchdog.
258 * @wdd: the watchdog device to start
259 *
260 * The caller must hold wd_data->lock.
261 *
262 * Start the watchdog if it is not active and mark it active.
263 * This function returns zero on success or a negative errno code for
264 * failure.
265 */
266
267static int watchdog_start(struct watchdog_device *wdd)
268{
269 struct watchdog_core_data *wd_data = wdd->wd_data;
270 ktime_t started_at;
271 int err;
272
273 if (watchdog_active(wdd))
274 return 0;
275
276 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
277
278 started_at = ktime_get();
279 if (watchdog_hw_running(wdd) && wdd->ops->ping)
280 err = wdd->ops->ping(wdd);
281 else
282 err = wdd->ops->start(wdd);
283 if (err == 0) {
284 set_bit(WDOG_ACTIVE, &wdd->status);
285 wd_data->last_keepalive = started_at;
286 watchdog_update_worker(wdd);
287 }
288
289 return err;
290}
291
292/*
293 * watchdog_stop: wrapper to stop the watchdog.
294 * @wdd: the watchdog device to stop
295 *
296 * The caller must hold wd_data->lock.
297 *
298 * Stop the watchdog if it is still active and unmark it active.
299 * This function returns zero on success or a negative errno code for
300 * failure.
301 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
302 */
303
304static int watchdog_stop(struct watchdog_device *wdd)
305{
306 int err = 0;
307
308 if (!watchdog_active(wdd))
309 return 0;
310
311 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
312 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
313 wdd->id);
314 return -EBUSY;
315 }
316
317 if (wdd->ops->stop) {
318 clear_bit(WDOG_HW_RUNNING, &wdd->status);
319 err = wdd->ops->stop(wdd);
320 } else {
321 set_bit(WDOG_HW_RUNNING, &wdd->status);
322 }
323
324 if (err == 0) {
325 clear_bit(WDOG_ACTIVE, &wdd->status);
326 watchdog_update_worker(wdd);
327 }
328
329 return err;
330}
331
332/*
333 * watchdog_get_status: wrapper to get the watchdog status
334 * @wdd: the watchdog device to get the status from
335 *
336 * The caller must hold wd_data->lock.
337 *
338 * Get the watchdog's status flags.
339 */
340
341static unsigned int watchdog_get_status(struct watchdog_device *wdd)
342{
343 struct watchdog_core_data *wd_data = wdd->wd_data;
344 unsigned int status;
345
346 if (wdd->ops->status)
347 status = wdd->ops->status(wdd);
348 else
349 status = wdd->bootstatus & (WDIOF_CARDRESET |
350 WDIOF_OVERHEAT |
351 WDIOF_FANFAULT |
352 WDIOF_EXTERN1 |
353 WDIOF_EXTERN2 |
354 WDIOF_POWERUNDER |
355 WDIOF_POWEROVER);
356
357 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
358 status |= WDIOF_MAGICCLOSE;
359
360 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
361 status |= WDIOF_KEEPALIVEPING;
362
363 return status;
364}
365
366/*
367 * watchdog_set_timeout: set the watchdog timer timeout
368 * @wdd: the watchdog device to set the timeout for
369 * @timeout: timeout to set in seconds
370 *
371 * The caller must hold wd_data->lock.
372 */
373
374static int watchdog_set_timeout(struct watchdog_device *wdd,
375 unsigned int timeout)
376{
377 int err = 0;
378
379 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
380 return -EOPNOTSUPP;
381
382 if (watchdog_timeout_invalid(wdd, timeout))
383 return -EINVAL;
384
385 if (wdd->ops->set_timeout) {
386 err = wdd->ops->set_timeout(wdd, timeout);
387 } else {
388 wdd->timeout = timeout;
389 /* Disable pretimeout if it doesn't fit the new timeout */
390 if (wdd->pretimeout >= wdd->timeout)
391 wdd->pretimeout = 0;
392 }
393
394 watchdog_update_worker(wdd);
395
396 return err;
397}
398
399/*
400 * watchdog_set_pretimeout: set the watchdog timer pretimeout
401 * @wdd: the watchdog device to set the timeout for
402 * @timeout: pretimeout to set in seconds
403 */
404
405static int watchdog_set_pretimeout(struct watchdog_device *wdd,
406 unsigned int timeout)
407{
408 int err = 0;
409
410 if (!(wdd->info->options & WDIOF_PRETIMEOUT))
411 return -EOPNOTSUPP;
412
413 if (watchdog_pretimeout_invalid(wdd, timeout))
414 return -EINVAL;
415
416 if (wdd->ops->set_pretimeout)
417 err = wdd->ops->set_pretimeout(wdd, timeout);
418 else
419 wdd->pretimeout = timeout;
420
421 return err;
422}
423
424/*
425 * watchdog_get_timeleft: wrapper to get the time left before a reboot
426 * @wdd: the watchdog device to get the remaining time from
427 * @timeleft: the time that's left
428 *
429 * The caller must hold wd_data->lock.
430 *
431 * Get the time before a watchdog will reboot (if not pinged).
432 */
433
434static int watchdog_get_timeleft(struct watchdog_device *wdd,
435 unsigned int *timeleft)
436{
437 *timeleft = 0;
438
439 if (!wdd->ops->get_timeleft)
440 return -EOPNOTSUPP;
441
442 *timeleft = wdd->ops->get_timeleft(wdd);
443
444 return 0;
445}
446
447#ifdef CONFIG_WATCHDOG_SYSFS
448static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
449 char *buf)
450{
451 struct watchdog_device *wdd = dev_get_drvdata(dev);
452
453 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
454}
455static DEVICE_ATTR_RO(nowayout);
456
457static ssize_t status_show(struct device *dev, struct device_attribute *attr,
458 char *buf)
459{
460 struct watchdog_device *wdd = dev_get_drvdata(dev);
461 struct watchdog_core_data *wd_data = wdd->wd_data;
462 unsigned int status;
463
464 mutex_lock(&wd_data->lock);
465 status = watchdog_get_status(wdd);
466 mutex_unlock(&wd_data->lock);
467
468 return sprintf(buf, "0x%x\n", status);
469}
470static DEVICE_ATTR_RO(status);
471
472static ssize_t bootstatus_show(struct device *dev,
473 struct device_attribute *attr, char *buf)
474{
475 struct watchdog_device *wdd = dev_get_drvdata(dev);
476
477 return sprintf(buf, "%u\n", wdd->bootstatus);
478}
479static DEVICE_ATTR_RO(bootstatus);
480
481static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
482 char *buf)
483{
484 struct watchdog_device *wdd = dev_get_drvdata(dev);
485 struct watchdog_core_data *wd_data = wdd->wd_data;
486 ssize_t status;
487 unsigned int val;
488
489 mutex_lock(&wd_data->lock);
490 status = watchdog_get_timeleft(wdd, &val);
491 mutex_unlock(&wd_data->lock);
492 if (!status)
493 status = sprintf(buf, "%u\n", val);
494
495 return status;
496}
497static DEVICE_ATTR_RO(timeleft);
498
499static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
500 char *buf)
501{
502 struct watchdog_device *wdd = dev_get_drvdata(dev);
503
504 return sprintf(buf, "%u\n", wdd->timeout);
505}
506static DEVICE_ATTR_RO(timeout);
507
508static ssize_t pretimeout_show(struct device *dev,
509 struct device_attribute *attr, char *buf)
510{
511 struct watchdog_device *wdd = dev_get_drvdata(dev);
512
513 return sprintf(buf, "%u\n", wdd->pretimeout);
514}
515static DEVICE_ATTR_RO(pretimeout);
516
517static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
518 char *buf)
519{
520 struct watchdog_device *wdd = dev_get_drvdata(dev);
521
522 return sprintf(buf, "%s\n", wdd->info->identity);
523}
524static DEVICE_ATTR_RO(identity);
525
526static ssize_t state_show(struct device *dev, struct device_attribute *attr,
527 char *buf)
528{
529 struct watchdog_device *wdd = dev_get_drvdata(dev);
530
531 if (watchdog_active(wdd))
532 return sprintf(buf, "active\n");
533
534 return sprintf(buf, "inactive\n");
535}
536static DEVICE_ATTR_RO(state);
537
538static ssize_t pretimeout_available_governors_show(struct device *dev,
539 struct device_attribute *attr, char *buf)
540{
541 return watchdog_pretimeout_available_governors_get(buf);
542}
543static DEVICE_ATTR_RO(pretimeout_available_governors);
544
545static ssize_t pretimeout_governor_show(struct device *dev,
546 struct device_attribute *attr,
547 char *buf)
548{
549 struct watchdog_device *wdd = dev_get_drvdata(dev);
550
551 return watchdog_pretimeout_governor_get(wdd, buf);
552}
553
554static ssize_t pretimeout_governor_store(struct device *dev,
555 struct device_attribute *attr,
556 const char *buf, size_t count)
557{
558 struct watchdog_device *wdd = dev_get_drvdata(dev);
559 int ret = watchdog_pretimeout_governor_set(wdd, buf);
560
561 if (!ret)
562 ret = count;
563
564 return ret;
565}
566static DEVICE_ATTR_RW(pretimeout_governor);
567
568static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
569 int n)
570{
571 struct device *dev = container_of(kobj, struct device, kobj);
572 struct watchdog_device *wdd = dev_get_drvdata(dev);
573 umode_t mode = attr->mode;
574
575 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
576 mode = 0;
577 else if (attr == &dev_attr_pretimeout.attr &&
578 !(wdd->info->options & WDIOF_PRETIMEOUT))
579 mode = 0;
580 else if ((attr == &dev_attr_pretimeout_governor.attr ||
581 attr == &dev_attr_pretimeout_available_governors.attr) &&
582 (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
583 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
584 mode = 0;
585
586 return mode;
587}
588static struct attribute *wdt_attrs[] = {
589 &dev_attr_state.attr,
590 &dev_attr_identity.attr,
591 &dev_attr_timeout.attr,
592 &dev_attr_pretimeout.attr,
593 &dev_attr_timeleft.attr,
594 &dev_attr_bootstatus.attr,
595 &dev_attr_status.attr,
596 &dev_attr_nowayout.attr,
597 &dev_attr_pretimeout_governor.attr,
598 &dev_attr_pretimeout_available_governors.attr,
599 NULL,
600};
601
602static const struct attribute_group wdt_group = {
603 .attrs = wdt_attrs,
604 .is_visible = wdt_is_visible,
605};
606__ATTRIBUTE_GROUPS(wdt);
607#else
608#define wdt_groups NULL
609#endif
610
611/*
612 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
613 * @wdd: the watchdog device to do the ioctl on
614 * @cmd: watchdog command
615 * @arg: argument pointer
616 *
617 * The caller must hold wd_data->lock.
618 */
619
620static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
621 unsigned long arg)
622{
623 if (!wdd->ops->ioctl)
624 return -ENOIOCTLCMD;
625
626 return wdd->ops->ioctl(wdd, cmd, arg);
627}
628
629/*
630 * watchdog_write: writes to the watchdog.
631 * @file: file from VFS
632 * @data: user address of data
633 * @len: length of data
634 * @ppos: pointer to the file offset
635 *
636 * A write to a watchdog device is defined as a keepalive ping.
637 * Writing the magic 'V' sequence allows the next close to turn
638 * off the watchdog (if 'nowayout' is not set).
639 */
640
641static ssize_t watchdog_write(struct file *file, const char __user *data,
642 size_t len, loff_t *ppos)
643{
644 struct watchdog_core_data *wd_data = file->private_data;
645 struct watchdog_device *wdd;
646 int err;
647 size_t i;
648 char c;
649
650 if (len == 0)
651 return 0;
652
653 /*
654 * Note: just in case someone wrote the magic character
655 * five months ago...
656 */
657 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
658
659 /* scan to see whether or not we got the magic character */
660 for (i = 0; i != len; i++) {
661 if (get_user(c, data + i))
662 return -EFAULT;
663 if (c == 'V')
664 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
665 }
666
667 /* someone wrote to us, so we send the watchdog a keepalive ping */
668
669 err = -ENODEV;
670 mutex_lock(&wd_data->lock);
671 wdd = wd_data->wdd;
672 if (wdd)
673 err = watchdog_ping(wdd);
674 mutex_unlock(&wd_data->lock);
675
676 if (err < 0)
677 return err;
678
679 return len;
680}
681
682/*
683 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
684 * @file: file handle to the device
685 * @cmd: watchdog command
686 * @arg: argument pointer
687 *
688 * The watchdog API defines a common set of functions for all watchdogs
689 * according to their available features.
690 */
691
692static long watchdog_ioctl(struct file *file, unsigned int cmd,
693 unsigned long arg)
694{
695 struct watchdog_core_data *wd_data = file->private_data;
696 void __user *argp = (void __user *)arg;
697 struct watchdog_device *wdd;
698 int __user *p = argp;
699 unsigned int val;
700 int err;
701
702 mutex_lock(&wd_data->lock);
703
704 wdd = wd_data->wdd;
705 if (!wdd) {
706 err = -ENODEV;
707 goto out_ioctl;
708 }
709
710 err = watchdog_ioctl_op(wdd, cmd, arg);
711 if (err != -ENOIOCTLCMD)
712 goto out_ioctl;
713
714 switch (cmd) {
715 case WDIOC_GETSUPPORT:
716 err = copy_to_user(argp, wdd->info,
717 sizeof(struct watchdog_info)) ? -EFAULT : 0;
718 break;
719 case WDIOC_GETSTATUS:
720 val = watchdog_get_status(wdd);
721 err = put_user(val, p);
722 break;
723 case WDIOC_GETBOOTSTATUS:
724 err = put_user(wdd->bootstatus, p);
725 break;
726 case WDIOC_SETOPTIONS:
727 if (get_user(val, p)) {
728 err = -EFAULT;
729 break;
730 }
731 if (val & WDIOS_DISABLECARD) {
732 err = watchdog_stop(wdd);
733 if (err < 0)
734 break;
735 }
736 if (val & WDIOS_ENABLECARD)
737 err = watchdog_start(wdd);
738 break;
739 case WDIOC_KEEPALIVE:
740 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
741 err = -EOPNOTSUPP;
742 break;
743 }
744 err = watchdog_ping(wdd);
745 break;
746 case WDIOC_SETTIMEOUT:
747 if (get_user(val, p)) {
748 err = -EFAULT;
749 break;
750 }
751 err = watchdog_set_timeout(wdd, val);
752 if (err < 0)
753 break;
754 /* If the watchdog is active then we send a keepalive ping
755 * to make sure that the watchdog keep's running (and if
756 * possible that it takes the new timeout) */
757 err = watchdog_ping(wdd);
758 if (err < 0)
759 break;
760 /* fall through */
761 case WDIOC_GETTIMEOUT:
762 /* timeout == 0 means that we don't know the timeout */
763 if (wdd->timeout == 0) {
764 err = -EOPNOTSUPP;
765 break;
766 }
767 err = put_user(wdd->timeout, p);
768 break;
769 case WDIOC_GETTIMELEFT:
770 err = watchdog_get_timeleft(wdd, &val);
771 if (err < 0)
772 break;
773 err = put_user(val, p);
774 break;
775 case WDIOC_SETPRETIMEOUT:
776 if (get_user(val, p)) {
777 err = -EFAULT;
778 break;
779 }
780 err = watchdog_set_pretimeout(wdd, val);
781 break;
782 case WDIOC_GETPRETIMEOUT:
783 err = put_user(wdd->pretimeout, p);
784 break;
785 default:
786 err = -ENOTTY;
787 break;
788 }
789
790out_ioctl:
791 mutex_unlock(&wd_data->lock);
792 return err;
793}
794
795/*
796 * watchdog_open: open the /dev/watchdog* devices.
797 * @inode: inode of device
798 * @file: file handle to device
799 *
800 * When the /dev/watchdog* device gets opened, we start the watchdog.
801 * Watch out: the /dev/watchdog device is single open, so we make sure
802 * it can only be opened once.
803 */
804
805static int watchdog_open(struct inode *inode, struct file *file)
806{
807 struct watchdog_core_data *wd_data;
808 struct watchdog_device *wdd;
809 bool hw_running;
810 int err;
811
812 /* Get the corresponding watchdog device */
813 if (imajor(inode) == MISC_MAJOR)
814 wd_data = old_wd_data;
815 else
816 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
817 cdev);
818
819 /* the watchdog is single open! */
820 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
821 return -EBUSY;
822
823 wdd = wd_data->wdd;
824
825 /*
826 * If the /dev/watchdog device is open, we don't want the module
827 * to be unloaded.
828 */
829 hw_running = watchdog_hw_running(wdd);
830 if (!hw_running && !try_module_get(wdd->ops->owner)) {
831 err = -EBUSY;
832 goto out_clear;
833 }
834
835 err = watchdog_start(wdd);
836 if (err < 0)
837 goto out_mod;
838
839 file->private_data = wd_data;
840
841 if (!hw_running)
842 kref_get(&wd_data->kref);
843
844 /*
845 * open_timeout only applies for the first open from
846 * userspace. Set open_deadline to infinity so that the kernel
847 * will take care of an always-running hardware watchdog in
848 * case the device gets magic-closed or WDIOS_DISABLECARD is
849 * applied.
850 */
851 wd_data->open_deadline = KTIME_MAX;
852
853 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
854 return stream_open(inode, file);
855
856out_mod:
857 module_put(wd_data->wdd->ops->owner);
858out_clear:
859 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
860 return err;
861}
862
863static void watchdog_core_data_release(struct kref *kref)
864{
865 struct watchdog_core_data *wd_data;
866
867 wd_data = container_of(kref, struct watchdog_core_data, kref);
868
869 kfree(wd_data);
870}
871
872/*
873 * watchdog_release: release the watchdog device.
874 * @inode: inode of device
875 * @file: file handle to device
876 *
877 * This is the code for when /dev/watchdog gets closed. We will only
878 * stop the watchdog when we have received the magic char (and nowayout
879 * was not set), else the watchdog will keep running.
880 */
881
882static int watchdog_release(struct inode *inode, struct file *file)
883{
884 struct watchdog_core_data *wd_data = file->private_data;
885 struct watchdog_device *wdd;
886 int err = -EBUSY;
887 bool running;
888
889 mutex_lock(&wd_data->lock);
890
891 wdd = wd_data->wdd;
892 if (!wdd)
893 goto done;
894
895 /*
896 * We only stop the watchdog if we received the magic character
897 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
898 * watchdog_stop will fail.
899 */
900 if (!test_bit(WDOG_ACTIVE, &wdd->status))
901 err = 0;
902 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
903 !(wdd->info->options & WDIOF_MAGICCLOSE))
904 err = watchdog_stop(wdd);
905
906 /* If the watchdog was not stopped, send a keepalive ping */
907 if (err < 0) {
908 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
909 watchdog_ping(wdd);
910 }
911
912 watchdog_update_worker(wdd);
913
914 /* make sure that /dev/watchdog can be re-opened */
915 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
916
917done:
918 running = wdd && watchdog_hw_running(wdd);
919 mutex_unlock(&wd_data->lock);
920 /*
921 * Allow the owner module to be unloaded again unless the watchdog
922 * is still running. If the watchdog is still running, it can not
923 * be stopped, and its driver must not be unloaded.
924 */
925 if (!running) {
926 module_put(wd_data->cdev.owner);
927 kref_put(&wd_data->kref, watchdog_core_data_release);
928 }
929 return 0;
930}
931
932static const struct file_operations watchdog_fops = {
933 .owner = THIS_MODULE,
934 .write = watchdog_write,
935 .unlocked_ioctl = watchdog_ioctl,
936 .open = watchdog_open,
937 .release = watchdog_release,
938};
939
940static struct miscdevice watchdog_miscdev = {
941 .minor = WATCHDOG_MINOR,
942 .name = "watchdog",
943 .fops = &watchdog_fops,
944};
945
946/*
947 * watchdog_cdev_register: register watchdog character device
948 * @wdd: watchdog device
949 * @devno: character device number
950 *
951 * Register a watchdog character device including handling the legacy
952 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
953 * thus we set it up like that.
954 */
955
956static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
957{
958 struct watchdog_core_data *wd_data;
959 int err;
960
961 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
962 if (!wd_data)
963 return -ENOMEM;
964 kref_init(&wd_data->kref);
965 mutex_init(&wd_data->lock);
966
967 wd_data->wdd = wdd;
968 wdd->wd_data = wd_data;
969
970 if (IS_ERR_OR_NULL(watchdog_kworker))
971 return -ENODEV;
972
973 kthread_init_work(&wd_data->work, watchdog_ping_work);
974 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
975 wd_data->timer.function = watchdog_timer_expired;
976
977 if (wdd->id == 0) {
978 old_wd_data = wd_data;
979 watchdog_miscdev.parent = wdd->parent;
980 err = misc_register(&watchdog_miscdev);
981 if (err != 0) {
982 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
983 wdd->info->identity, WATCHDOG_MINOR, err);
984 if (err == -EBUSY)
985 pr_err("%s: a legacy watchdog module is probably present.\n",
986 wdd->info->identity);
987 old_wd_data = NULL;
988 kfree(wd_data);
989 return err;
990 }
991 }
992
993 /* Fill in the data structures */
994 cdev_init(&wd_data->cdev, &watchdog_fops);
995 wd_data->cdev.owner = wdd->ops->owner;
996
997 /* Add the device */
998 err = cdev_add(&wd_data->cdev, devno, 1);
999 if (err) {
1000 pr_err("watchdog%d unable to add device %d:%d\n",
1001 wdd->id, MAJOR(watchdog_devt), wdd->id);
1002 if (wdd->id == 0) {
1003 misc_deregister(&watchdog_miscdev);
1004 old_wd_data = NULL;
1005 kref_put(&wd_data->kref, watchdog_core_data_release);
1006 }
1007 return err;
1008 }
1009
1010 /* Record time of most recent heartbeat as 'just before now'. */
1011 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
1012 watchdog_set_open_deadline(wd_data);
1013
1014 /*
1015 * If the watchdog is running, prevent its driver from being unloaded,
1016 * and schedule an immediate ping.
1017 */
1018 if (watchdog_hw_running(wdd)) {
1019 __module_get(wdd->ops->owner);
1020 kref_get(&wd_data->kref);
1021 if (handle_boot_enabled)
1022 hrtimer_start(&wd_data->timer, 0, HRTIMER_MODE_REL);
1023 else
1024 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
1025 wdd->id);
1026 }
1027
1028 return 0;
1029}
1030
1031/*
1032 * watchdog_cdev_unregister: unregister watchdog character device
1033 * @watchdog: watchdog device
1034 *
1035 * Unregister watchdog character device and if needed the legacy
1036 * /dev/watchdog device.
1037 */
1038
1039static void watchdog_cdev_unregister(struct watchdog_device *wdd)
1040{
1041 struct watchdog_core_data *wd_data = wdd->wd_data;
1042
1043 cdev_del(&wd_data->cdev);
1044 if (wdd->id == 0) {
1045 misc_deregister(&watchdog_miscdev);
1046 old_wd_data = NULL;
1047 }
1048
1049 if (watchdog_active(wdd) &&
1050 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
1051 watchdog_stop(wdd);
1052 }
1053
1054 mutex_lock(&wd_data->lock);
1055 wd_data->wdd = NULL;
1056 wdd->wd_data = NULL;
1057 mutex_unlock(&wd_data->lock);
1058
1059 hrtimer_cancel(&wd_data->timer);
1060 kthread_cancel_work_sync(&wd_data->work);
1061
1062 kref_put(&wd_data->kref, watchdog_core_data_release);
1063}
1064
1065static struct class watchdog_class = {
1066 .name = "watchdog",
1067 .owner = THIS_MODULE,
1068 .dev_groups = wdt_groups,
1069};
1070
1071static int watchdog_reboot_notifier(struct notifier_block *nb,
1072 unsigned long code, void *data)
1073{
1074 struct watchdog_device *wdd;
1075
1076 wdd = container_of(nb, struct watchdog_device, reboot_nb);
1077 if (code == SYS_DOWN || code == SYS_HALT) {
1078 if (watchdog_active(wdd)) {
1079 int ret;
1080
1081 ret = wdd->ops->stop(wdd);
1082 if (ret)
1083 return NOTIFY_BAD;
1084 }
1085 }
1086
1087 return NOTIFY_DONE;
1088}
1089
1090/*
1091 * watchdog_dev_register: register a watchdog device
1092 * @wdd: watchdog device
1093 *
1094 * Register a watchdog device including handling the legacy
1095 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1096 * thus we set it up like that.
1097 */
1098
1099int watchdog_dev_register(struct watchdog_device *wdd)
1100{
1101 struct device *dev;
1102 dev_t devno;
1103 int ret;
1104
1105 devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
1106
1107 ret = watchdog_cdev_register(wdd, devno);
1108 if (ret)
1109 return ret;
1110
1111 dev = device_create_with_groups(&watchdog_class, wdd->parent,
1112 devno, wdd, wdd->groups,
1113 "watchdog%d", wdd->id);
1114 if (IS_ERR(dev)) {
1115 watchdog_cdev_unregister(wdd);
1116 return PTR_ERR(dev);
1117 }
1118
1119 ret = watchdog_register_pretimeout(wdd);
1120 if (ret) {
1121 device_destroy(&watchdog_class, devno);
1122 watchdog_cdev_unregister(wdd);
1123 return ret;
1124 }
1125
1126 if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
1127 wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
1128
1129 ret = devm_register_reboot_notifier(dev, &wdd->reboot_nb);
1130 if (ret) {
1131 pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
1132 wdd->id, ret);
1133 watchdog_dev_unregister(wdd);
1134 }
1135 }
1136
1137 return ret;
1138}
1139
1140/*
1141 * watchdog_dev_unregister: unregister a watchdog device
1142 * @watchdog: watchdog device
1143 *
1144 * Unregister watchdog device and if needed the legacy
1145 * /dev/watchdog device.
1146 */
1147
1148void watchdog_dev_unregister(struct watchdog_device *wdd)
1149{
1150 watchdog_unregister_pretimeout(wdd);
1151 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
1152 watchdog_cdev_unregister(wdd);
1153}
1154
1155/*
1156 * watchdog_dev_init: init dev part of watchdog core
1157 *
1158 * Allocate a range of chardev nodes to use for watchdog devices
1159 */
1160
1161int __init watchdog_dev_init(void)
1162{
1163 int err;
1164 struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,};
1165
1166 watchdog_kworker = kthread_create_worker(0, "watchdogd");
1167 if (IS_ERR(watchdog_kworker)) {
1168 pr_err("Failed to create watchdog kworker\n");
1169 return PTR_ERR(watchdog_kworker);
1170 }
1171 sched_setscheduler(watchdog_kworker->task, SCHED_FIFO, ¶m);
1172
1173 err = class_register(&watchdog_class);
1174 if (err < 0) {
1175 pr_err("couldn't register class\n");
1176 goto err_register;
1177 }
1178
1179 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1180 if (err < 0) {
1181 pr_err("watchdog: unable to allocate char dev region\n");
1182 goto err_alloc;
1183 }
1184
1185 return 0;
1186
1187err_alloc:
1188 class_unregister(&watchdog_class);
1189err_register:
1190 kthread_destroy_worker(watchdog_kworker);
1191 return err;
1192}
1193
1194/*
1195 * watchdog_dev_exit: exit dev part of watchdog core
1196 *
1197 * Release the range of chardev nodes used for watchdog devices
1198 */
1199
1200void __exit watchdog_dev_exit(void)
1201{
1202 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1203 class_unregister(&watchdog_class);
1204 kthread_destroy_worker(watchdog_kworker);
1205}
1206
1207module_param(handle_boot_enabled, bool, 0444);
1208MODULE_PARM_DESC(handle_boot_enabled,
1209 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1210 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");
1211
1212module_param(open_timeout, uint, 0644);
1213MODULE_PARM_DESC(open_timeout,
1214 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
1215 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");