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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * watchdog_dev.c
4 *
5 * (c) Copyright 2008-2011 Alan Cox <[email protected]>,
6 * All Rights Reserved.
7 *
8 * (c) Copyright 2008-2011 Wim Van Sebroeck <[email protected]>.
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 <[email protected]>,
20 * Rob Radez <[email protected]>,
21 * Rusty Lynch <[email protected]>
22 * Satyam Sharma <[email protected]>
23 * Randy Dunlap <[email protected]>
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/kstrtox.h> /* For kstrto* */
39#include <linux/kthread.h> /* For kthread_work */
40#include <linux/miscdevice.h> /* For handling misc devices */
41#include <linux/module.h> /* For module stuff/... */
42#include <linux/mutex.h> /* For mutexes */
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 "watchdog_core.h"
49#include "watchdog_pretimeout.h"
50
51#include <trace/events/watchdog.h>
52
53/* the dev_t structure to store the dynamically allocated watchdog devices */
54static dev_t watchdog_devt;
55/* Reference to watchdog device behind /dev/watchdog */
56static struct watchdog_core_data *old_wd_data;
57
58static struct kthread_worker *watchdog_kworker;
59
60static bool handle_boot_enabled =
61 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
62
63static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
64
65static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
66{
67 return ktime_after(ktime_get(), data->open_deadline);
68}
69
70static void watchdog_set_open_deadline(struct watchdog_core_data *data)
71{
72 data->open_deadline = open_timeout ?
73 ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;
74}
75
76static inline bool watchdog_need_worker(struct watchdog_device *wdd)
77{
78 /* All variables in milli-seconds */
79 unsigned int hm = wdd->max_hw_heartbeat_ms;
80 unsigned int t = wdd->timeout * 1000;
81
82 /*
83 * A worker to generate heartbeat requests is needed if all of the
84 * following conditions are true.
85 * - Userspace activated the watchdog.
86 * - The driver provided a value for the maximum hardware timeout, and
87 * thus is aware that the framework supports generating heartbeat
88 * requests.
89 * - Userspace requests a longer timeout than the hardware can handle.
90 *
91 * Alternatively, if userspace has not opened the watchdog
92 * device, we take care of feeding the watchdog if it is
93 * running.
94 */
95 return (hm && watchdog_active(wdd) && t > hm) ||
96 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
97}
98
99static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
100{
101 struct watchdog_core_data *wd_data = wdd->wd_data;
102 unsigned int timeout_ms = wdd->timeout * 1000;
103 ktime_t keepalive_interval;
104 ktime_t last_heartbeat, latest_heartbeat;
105 ktime_t virt_timeout;
106 unsigned int hw_heartbeat_ms;
107
108 if (watchdog_active(wdd))
109 virt_timeout = ktime_add(wd_data->last_keepalive,
110 ms_to_ktime(timeout_ms));
111 else
112 virt_timeout = wd_data->open_deadline;
113
114 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
115 keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
116
117 /*
118 * To ensure that the watchdog times out wdd->timeout seconds
119 * after the most recent ping from userspace, the last
120 * worker ping has to come in hw_heartbeat_ms before this timeout.
121 */
122 last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
123 latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
124 if (ktime_before(latest_heartbeat, keepalive_interval))
125 return latest_heartbeat;
126 return keepalive_interval;
127}
128
129static inline void watchdog_update_worker(struct watchdog_device *wdd)
130{
131 struct watchdog_core_data *wd_data = wdd->wd_data;
132
133 if (watchdog_need_worker(wdd)) {
134 ktime_t t = watchdog_next_keepalive(wdd);
135
136 if (t > 0)
137 hrtimer_start(&wd_data->timer, t,
138 HRTIMER_MODE_REL_HARD);
139 } else {
140 hrtimer_cancel(&wd_data->timer);
141 }
142}
143
144static int __watchdog_ping(struct watchdog_device *wdd)
145{
146 struct watchdog_core_data *wd_data = wdd->wd_data;
147 ktime_t earliest_keepalive, now;
148 int err;
149
150 earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
151 ms_to_ktime(wdd->min_hw_heartbeat_ms));
152 now = ktime_get();
153
154 if (ktime_after(earliest_keepalive, now)) {
155 hrtimer_start(&wd_data->timer,
156 ktime_sub(earliest_keepalive, now),
157 HRTIMER_MODE_REL_HARD);
158 return 0;
159 }
160
161 wd_data->last_hw_keepalive = now;
162
163 if (wdd->ops->ping) {
164 err = wdd->ops->ping(wdd); /* ping the watchdog */
165 trace_watchdog_ping(wdd, err);
166 } else {
167 err = wdd->ops->start(wdd); /* restart watchdog */
168 trace_watchdog_start(wdd, err);
169 }
170
171 if (err == 0)
172 watchdog_hrtimer_pretimeout_start(wdd);
173
174 watchdog_update_worker(wdd);
175
176 return err;
177}
178
179/**
180 * watchdog_ping - ping the watchdog
181 * @wdd: The watchdog device to ping
182 *
183 * If the watchdog has no own ping operation then it needs to be
184 * restarted via the start operation. This wrapper function does
185 * exactly that.
186 * We only ping when the watchdog device is running.
187 * The caller must hold wd_data->lock.
188 *
189 * Return: 0 on success, error otherwise.
190 */
191static int watchdog_ping(struct watchdog_device *wdd)
192{
193 struct watchdog_core_data *wd_data = wdd->wd_data;
194
195 if (!watchdog_hw_running(wdd))
196 return 0;
197
198 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
199
200 wd_data->last_keepalive = ktime_get();
201 return __watchdog_ping(wdd);
202}
203
204static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
205{
206 struct watchdog_device *wdd = wd_data->wdd;
207
208 if (!wdd)
209 return false;
210
211 if (watchdog_active(wdd))
212 return true;
213
214 return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);
215}
216
217static void watchdog_ping_work(struct kthread_work *work)
218{
219 struct watchdog_core_data *wd_data;
220
221 wd_data = container_of(work, struct watchdog_core_data, work);
222
223 mutex_lock(&wd_data->lock);
224 if (watchdog_worker_should_ping(wd_data))
225 __watchdog_ping(wd_data->wdd);
226 mutex_unlock(&wd_data->lock);
227}
228
229static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
230{
231 struct watchdog_core_data *wd_data;
232
233 wd_data = container_of(timer, struct watchdog_core_data, timer);
234
235 kthread_queue_work(watchdog_kworker, &wd_data->work);
236 return HRTIMER_NORESTART;
237}
238
239/**
240 * watchdog_start - wrapper to start the watchdog
241 * @wdd: The watchdog device to start
242 *
243 * Start the watchdog if it is not active and mark it active.
244 * The caller must hold wd_data->lock.
245 *
246 * Return: 0 on success or a negative errno code for failure.
247 */
248static int watchdog_start(struct watchdog_device *wdd)
249{
250 struct watchdog_core_data *wd_data = wdd->wd_data;
251 ktime_t started_at;
252 int err;
253
254 if (watchdog_active(wdd))
255 return 0;
256
257 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
258
259 started_at = ktime_get();
260 if (watchdog_hw_running(wdd) && wdd->ops->ping) {
261 err = __watchdog_ping(wdd);
262 if (err == 0) {
263 set_bit(WDOG_ACTIVE, &wdd->status);
264 watchdog_hrtimer_pretimeout_start(wdd);
265 }
266 } else {
267 err = wdd->ops->start(wdd);
268 trace_watchdog_start(wdd, err);
269 if (err == 0) {
270 set_bit(WDOG_ACTIVE, &wdd->status);
271 set_bit(WDOG_HW_RUNNING, &wdd->status);
272 wd_data->last_keepalive = started_at;
273 wd_data->last_hw_keepalive = started_at;
274 watchdog_update_worker(wdd);
275 watchdog_hrtimer_pretimeout_start(wdd);
276 }
277 }
278
279 return err;
280}
281
282/**
283 * watchdog_stop - wrapper to stop the watchdog
284 * @wdd: The watchdog device to stop
285 *
286 * Stop the watchdog if it is still active and unmark it active.
287 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
288 * The caller must hold wd_data->lock.
289 *
290 * Return: 0 on success or a negative errno code for failure.
291 */
292static int watchdog_stop(struct watchdog_device *wdd)
293{
294 int err = 0;
295
296 if (!watchdog_active(wdd))
297 return 0;
298
299 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
300 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
301 wdd->id);
302 return -EBUSY;
303 }
304
305 if (wdd->ops->stop) {
306 clear_bit(WDOG_HW_RUNNING, &wdd->status);
307 err = wdd->ops->stop(wdd);
308 trace_watchdog_stop(wdd, err);
309 } else {
310 set_bit(WDOG_HW_RUNNING, &wdd->status);
311 }
312
313 if (err == 0) {
314 clear_bit(WDOG_ACTIVE, &wdd->status);
315 watchdog_update_worker(wdd);
316 watchdog_hrtimer_pretimeout_stop(wdd);
317 }
318
319 return err;
320}
321
322/**
323 * watchdog_get_status - wrapper to get the watchdog status
324 * @wdd: The watchdog device to get the status from
325 *
326 * Get the watchdog's status flags.
327 * The caller must hold wd_data->lock.
328 *
329 * Return: watchdog's status flags.
330 */
331static unsigned int watchdog_get_status(struct watchdog_device *wdd)
332{
333 struct watchdog_core_data *wd_data = wdd->wd_data;
334 unsigned int status;
335
336 if (wdd->ops->status)
337 status = wdd->ops->status(wdd);
338 else
339 status = wdd->bootstatus & (WDIOF_CARDRESET |
340 WDIOF_OVERHEAT |
341 WDIOF_FANFAULT |
342 WDIOF_EXTERN1 |
343 WDIOF_EXTERN2 |
344 WDIOF_POWERUNDER |
345 WDIOF_POWEROVER);
346
347 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
348 status |= WDIOF_MAGICCLOSE;
349
350 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
351 status |= WDIOF_KEEPALIVEPING;
352
353 if (IS_ENABLED(CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT))
354 status |= WDIOF_PRETIMEOUT;
355
356 return status;
357}
358
359/**
360 * watchdog_set_timeout - set the watchdog timer timeout
361 * @wdd: The watchdog device to set the timeout for
362 * @timeout: Timeout to set in seconds
363 *
364 * The caller must hold wd_data->lock.
365 *
366 * Return: 0 if successful, error otherwise.
367 */
368static int watchdog_set_timeout(struct watchdog_device *wdd,
369 unsigned int timeout)
370{
371 int err = 0;
372
373 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
374 return -EOPNOTSUPP;
375
376 if (watchdog_timeout_invalid(wdd, timeout))
377 return -EINVAL;
378
379 if (wdd->ops->set_timeout) {
380 err = wdd->ops->set_timeout(wdd, timeout);
381 trace_watchdog_set_timeout(wdd, timeout, err);
382 } else {
383 wdd->timeout = timeout;
384 /* Disable pretimeout if it doesn't fit the new timeout */
385 if (wdd->pretimeout >= wdd->timeout)
386 wdd->pretimeout = 0;
387 }
388
389 watchdog_update_worker(wdd);
390
391 return err;
392}
393
394/**
395 * watchdog_set_pretimeout - set the watchdog timer pretimeout
396 * @wdd: The watchdog device to set the timeout for
397 * @timeout: pretimeout to set in seconds
398 *
399 * Return: 0 if successful, error otherwise.
400 */
401static int watchdog_set_pretimeout(struct watchdog_device *wdd,
402 unsigned int timeout)
403{
404 int err = 0;
405
406 if (!watchdog_have_pretimeout(wdd))
407 return -EOPNOTSUPP;
408
409 if (watchdog_pretimeout_invalid(wdd, timeout))
410 return -EINVAL;
411
412 if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
413 err = wdd->ops->set_pretimeout(wdd, timeout);
414 else
415 wdd->pretimeout = timeout;
416
417 return err;
418}
419
420/**
421 * watchdog_get_timeleft - wrapper to get the time left before a reboot
422 * @wdd: The watchdog device to get the remaining time from
423 * @timeleft: The time that's left
424 *
425 * Get the time before a watchdog will reboot (if not pinged).
426 * The caller must hold wd_data->lock.
427 */
428static void watchdog_get_timeleft(struct watchdog_device *wdd,
429 unsigned int *timeleft)
430{
431 *timeleft = 0;
432
433 if (wdd->ops->get_timeleft) {
434 *timeleft = wdd->ops->get_timeleft(wdd);
435 } else {
436 struct watchdog_core_data *wd_data = wdd->wd_data;
437 s64 last_keepalive_ms = ktime_ms_delta(ktime_get(), wd_data->last_keepalive);
438 s64 last_keepalive = DIV_ROUND_UP_ULL(last_keepalive_ms, 1000);
439
440 if (wdd->timeout > last_keepalive)
441 *timeleft = wdd->timeout - last_keepalive;
442 }
443}
444
445#ifdef CONFIG_WATCHDOG_SYSFS
446static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
447 char *buf)
448{
449 struct watchdog_device *wdd = dev_get_drvdata(dev);
450
451 return sysfs_emit(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT,
452 &wdd->status));
453}
454
455static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,
456 const char *buf, size_t len)
457{
458 struct watchdog_device *wdd = dev_get_drvdata(dev);
459 unsigned int value;
460 int ret;
461
462 ret = kstrtouint(buf, 0, &value);
463 if (ret)
464 return ret;
465 if (value > 1)
466 return -EINVAL;
467 /* nowayout cannot be disabled once set */
468 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)
469 return -EPERM;
470 watchdog_set_nowayout(wdd, value);
471 return len;
472}
473static DEVICE_ATTR_RW(nowayout);
474
475static ssize_t status_show(struct device *dev, struct device_attribute *attr,
476 char *buf)
477{
478 struct watchdog_device *wdd = dev_get_drvdata(dev);
479 struct watchdog_core_data *wd_data = wdd->wd_data;
480 unsigned int status;
481
482 mutex_lock(&wd_data->lock);
483 status = watchdog_get_status(wdd);
484 mutex_unlock(&wd_data->lock);
485
486 return sysfs_emit(buf, "0x%x\n", status);
487}
488static DEVICE_ATTR_RO(status);
489
490static ssize_t bootstatus_show(struct device *dev,
491 struct device_attribute *attr, char *buf)
492{
493 struct watchdog_device *wdd = dev_get_drvdata(dev);
494
495 return sysfs_emit(buf, "%u\n", wdd->bootstatus);
496}
497static DEVICE_ATTR_RO(bootstatus);
498
499static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
500 char *buf)
501{
502 struct watchdog_device *wdd = dev_get_drvdata(dev);
503 struct watchdog_core_data *wd_data = wdd->wd_data;
504 unsigned int val;
505
506 mutex_lock(&wd_data->lock);
507 watchdog_get_timeleft(wdd, &val);
508 mutex_unlock(&wd_data->lock);
509
510 return sysfs_emit(buf, "%u\n", val);
511}
512static DEVICE_ATTR_RO(timeleft);
513
514static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
515 char *buf)
516{
517 struct watchdog_device *wdd = dev_get_drvdata(dev);
518
519 return sysfs_emit(buf, "%u\n", wdd->timeout);
520}
521static DEVICE_ATTR_RO(timeout);
522
523static ssize_t min_timeout_show(struct device *dev,
524 struct device_attribute *attr, char *buf)
525{
526 struct watchdog_device *wdd = dev_get_drvdata(dev);
527
528 return sysfs_emit(buf, "%u\n", wdd->min_timeout);
529}
530static DEVICE_ATTR_RO(min_timeout);
531
532static ssize_t max_timeout_show(struct device *dev,
533 struct device_attribute *attr, char *buf)
534{
535 struct watchdog_device *wdd = dev_get_drvdata(dev);
536
537 return sysfs_emit(buf, "%u\n", wdd->max_timeout);
538}
539static DEVICE_ATTR_RO(max_timeout);
540
541static ssize_t pretimeout_show(struct device *dev,
542 struct device_attribute *attr, char *buf)
543{
544 struct watchdog_device *wdd = dev_get_drvdata(dev);
545
546 return sysfs_emit(buf, "%u\n", wdd->pretimeout);
547}
548static DEVICE_ATTR_RO(pretimeout);
549
550static ssize_t options_show(struct device *dev, struct device_attribute *attr,
551 char *buf)
552{
553 struct watchdog_device *wdd = dev_get_drvdata(dev);
554
555 return sysfs_emit(buf, "0x%x\n", wdd->info->options);
556}
557static DEVICE_ATTR_RO(options);
558
559static ssize_t fw_version_show(struct device *dev, struct device_attribute *attr,
560 char *buf)
561{
562 struct watchdog_device *wdd = dev_get_drvdata(dev);
563
564 return sysfs_emit(buf, "%d\n", wdd->info->firmware_version);
565}
566static DEVICE_ATTR_RO(fw_version);
567
568static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
569 char *buf)
570{
571 struct watchdog_device *wdd = dev_get_drvdata(dev);
572
573 return sysfs_emit(buf, "%s\n", wdd->info->identity);
574}
575static DEVICE_ATTR_RO(identity);
576
577static ssize_t state_show(struct device *dev, struct device_attribute *attr,
578 char *buf)
579{
580 struct watchdog_device *wdd = dev_get_drvdata(dev);
581
582 if (watchdog_active(wdd))
583 return sysfs_emit(buf, "active\n");
584
585 return sysfs_emit(buf, "inactive\n");
586}
587static DEVICE_ATTR_RO(state);
588
589static ssize_t pretimeout_available_governors_show(struct device *dev,
590 struct device_attribute *attr, char *buf)
591{
592 return watchdog_pretimeout_available_governors_get(buf);
593}
594static DEVICE_ATTR_RO(pretimeout_available_governors);
595
596static ssize_t pretimeout_governor_show(struct device *dev,
597 struct device_attribute *attr,
598 char *buf)
599{
600 struct watchdog_device *wdd = dev_get_drvdata(dev);
601
602 return watchdog_pretimeout_governor_get(wdd, buf);
603}
604
605static ssize_t pretimeout_governor_store(struct device *dev,
606 struct device_attribute *attr,
607 const char *buf, size_t count)
608{
609 struct watchdog_device *wdd = dev_get_drvdata(dev);
610 int ret = watchdog_pretimeout_governor_set(wdd, buf);
611
612 if (!ret)
613 ret = count;
614
615 return ret;
616}
617static DEVICE_ATTR_RW(pretimeout_governor);
618
619static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
620 int n)
621{
622 struct device *dev = kobj_to_dev(kobj);
623 struct watchdog_device *wdd = dev_get_drvdata(dev);
624 umode_t mode = attr->mode;
625
626 if (attr == &dev_attr_pretimeout.attr && !watchdog_have_pretimeout(wdd))
627 mode = 0;
628 else if ((attr == &dev_attr_pretimeout_governor.attr ||
629 attr == &dev_attr_pretimeout_available_governors.attr) &&
630 (!watchdog_have_pretimeout(wdd) || !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
631 mode = 0;
632
633 return mode;
634}
635static struct attribute *wdt_attrs[] = {
636 &dev_attr_state.attr,
637 &dev_attr_options.attr,
638 &dev_attr_fw_version.attr,
639 &dev_attr_identity.attr,
640 &dev_attr_timeout.attr,
641 &dev_attr_min_timeout.attr,
642 &dev_attr_max_timeout.attr,
643 &dev_attr_pretimeout.attr,
644 &dev_attr_timeleft.attr,
645 &dev_attr_bootstatus.attr,
646 &dev_attr_status.attr,
647 &dev_attr_nowayout.attr,
648 &dev_attr_pretimeout_governor.attr,
649 &dev_attr_pretimeout_available_governors.attr,
650 NULL,
651};
652
653static const struct attribute_group wdt_group = {
654 .attrs = wdt_attrs,
655 .is_visible = wdt_is_visible,
656};
657__ATTRIBUTE_GROUPS(wdt);
658#else
659#define wdt_groups NULL
660#endif
661
662/**
663 * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
664 * @wdd: The watchdog device to do the ioctl on
665 * @cmd: Watchdog command
666 * @arg: Argument pointer
667 *
668 * The caller must hold wd_data->lock.
669 *
670 * Return: 0 if successful, error otherwise.
671 */
672static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
673 unsigned long arg)
674{
675 if (!wdd->ops->ioctl)
676 return -ENOIOCTLCMD;
677
678 return wdd->ops->ioctl(wdd, cmd, arg);
679}
680
681/**
682 * watchdog_write - writes to the watchdog
683 * @file: File from VFS
684 * @data: User address of data
685 * @len: Length of data
686 * @ppos: Pointer to the file offset
687 *
688 * A write to a watchdog device is defined as a keepalive ping.
689 * Writing the magic 'V' sequence allows the next close to turn
690 * off the watchdog (if 'nowayout' is not set).
691 *
692 * Return: @len if successful, error otherwise.
693 */
694static ssize_t watchdog_write(struct file *file, const char __user *data,
695 size_t len, loff_t *ppos)
696{
697 struct watchdog_core_data *wd_data = file->private_data;
698 struct watchdog_device *wdd;
699 int err;
700 size_t i;
701 char c;
702
703 if (len == 0)
704 return 0;
705
706 /*
707 * Note: just in case someone wrote the magic character
708 * five months ago...
709 */
710 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
711
712 /* scan to see whether or not we got the magic character */
713 for (i = 0; i != len; i++) {
714 if (get_user(c, data + i))
715 return -EFAULT;
716 if (c == 'V')
717 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
718 }
719
720 /* someone wrote to us, so we send the watchdog a keepalive ping */
721
722 err = -ENODEV;
723 mutex_lock(&wd_data->lock);
724 wdd = wd_data->wdd;
725 if (wdd)
726 err = watchdog_ping(wdd);
727 mutex_unlock(&wd_data->lock);
728
729 if (err < 0)
730 return err;
731
732 return len;
733}
734
735/**
736 * watchdog_ioctl - handle the different ioctl's for the watchdog device
737 * @file: File handle to the device
738 * @cmd: Watchdog command
739 * @arg: Argument pointer
740 *
741 * The watchdog API defines a common set of functions for all watchdogs
742 * according to their available features.
743 *
744 * Return: 0 if successful, error otherwise.
745 */
746
747static long watchdog_ioctl(struct file *file, unsigned int cmd,
748 unsigned long arg)
749{
750 struct watchdog_core_data *wd_data = file->private_data;
751 void __user *argp = (void __user *)arg;
752 struct watchdog_device *wdd;
753 int __user *p = argp;
754 unsigned int val;
755 int err;
756
757 mutex_lock(&wd_data->lock);
758
759 wdd = wd_data->wdd;
760 if (!wdd) {
761 err = -ENODEV;
762 goto out_ioctl;
763 }
764
765 err = watchdog_ioctl_op(wdd, cmd, arg);
766 if (err != -ENOIOCTLCMD)
767 goto out_ioctl;
768
769 switch (cmd) {
770 case WDIOC_GETSUPPORT:
771 err = copy_to_user(argp, wdd->info,
772 sizeof(struct watchdog_info)) ? -EFAULT : 0;
773 break;
774 case WDIOC_GETSTATUS:
775 val = watchdog_get_status(wdd);
776 err = put_user(val, p);
777 break;
778 case WDIOC_GETBOOTSTATUS:
779 err = put_user(wdd->bootstatus, p);
780 break;
781 case WDIOC_SETOPTIONS:
782 if (get_user(val, p)) {
783 err = -EFAULT;
784 break;
785 }
786 if (val & WDIOS_DISABLECARD) {
787 err = watchdog_stop(wdd);
788 if (err < 0)
789 break;
790 }
791 if (val & WDIOS_ENABLECARD)
792 err = watchdog_start(wdd);
793 break;
794 case WDIOC_KEEPALIVE:
795 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
796 err = -EOPNOTSUPP;
797 break;
798 }
799 err = watchdog_ping(wdd);
800 break;
801 case WDIOC_SETTIMEOUT:
802 if (get_user(val, p)) {
803 err = -EFAULT;
804 break;
805 }
806 err = watchdog_set_timeout(wdd, val);
807 if (err < 0)
808 break;
809 /* If the watchdog is active then we send a keepalive ping
810 * to make sure that the watchdog keep's running (and if
811 * possible that it takes the new timeout) */
812 err = watchdog_ping(wdd);
813 if (err < 0)
814 break;
815 fallthrough;
816 case WDIOC_GETTIMEOUT:
817 /* timeout == 0 means that we don't know the timeout */
818 if (wdd->timeout == 0) {
819 err = -EOPNOTSUPP;
820 break;
821 }
822 err = put_user(wdd->timeout, p);
823 break;
824 case WDIOC_GETTIMELEFT:
825 watchdog_get_timeleft(wdd, &val);
826 err = put_user(val, p);
827 break;
828 case WDIOC_SETPRETIMEOUT:
829 if (get_user(val, p)) {
830 err = -EFAULT;
831 break;
832 }
833 err = watchdog_set_pretimeout(wdd, val);
834 break;
835 case WDIOC_GETPRETIMEOUT:
836 err = put_user(wdd->pretimeout, p);
837 break;
838 default:
839 err = -ENOTTY;
840 break;
841 }
842
843out_ioctl:
844 mutex_unlock(&wd_data->lock);
845 return err;
846}
847
848/**
849 * watchdog_open - open the /dev/watchdog* devices
850 * @inode: Inode of device
851 * @file: File handle to device
852 *
853 * When the /dev/watchdog* device gets opened, we start the watchdog.
854 * Watch out: the /dev/watchdog device is single open, so we make sure
855 * it can only be opened once.
856 *
857 * Return: 0 if successful, error otherwise.
858 */
859static int watchdog_open(struct inode *inode, struct file *file)
860{
861 struct watchdog_core_data *wd_data;
862 struct watchdog_device *wdd;
863 bool hw_running;
864 int err;
865
866 /* Get the corresponding watchdog device */
867 if (imajor(inode) == MISC_MAJOR)
868 wd_data = old_wd_data;
869 else
870 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
871 cdev);
872
873 /* the watchdog is single open! */
874 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
875 return -EBUSY;
876
877 wdd = wd_data->wdd;
878
879 /*
880 * If the /dev/watchdog device is open, we don't want the module
881 * to be unloaded.
882 */
883 hw_running = watchdog_hw_running(wdd);
884 if (!hw_running && !try_module_get(wdd->ops->owner)) {
885 err = -EBUSY;
886 goto out_clear;
887 }
888
889 err = watchdog_start(wdd);
890 if (err < 0)
891 goto out_mod;
892
893 file->private_data = wd_data;
894
895 if (!hw_running)
896 get_device(&wd_data->dev);
897
898 /*
899 * open_timeout only applies for the first open from
900 * userspace. Set open_deadline to infinity so that the kernel
901 * will take care of an always-running hardware watchdog in
902 * case the device gets magic-closed or WDIOS_DISABLECARD is
903 * applied.
904 */
905 wd_data->open_deadline = KTIME_MAX;
906
907 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
908 return stream_open(inode, file);
909
910out_mod:
911 module_put(wd_data->wdd->ops->owner);
912out_clear:
913 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
914 return err;
915}
916
917static void watchdog_core_data_release(struct device *dev)
918{
919 struct watchdog_core_data *wd_data;
920
921 wd_data = container_of(dev, struct watchdog_core_data, dev);
922
923 kfree(wd_data);
924}
925
926/**
927 * watchdog_release - release the watchdog device
928 * @inode: Inode of device
929 * @file: File handle to device
930 *
931 * This is the code for when /dev/watchdog gets closed. We will only
932 * stop the watchdog when we have received the magic char (and nowayout
933 * was not set), else the watchdog will keep running.
934 *
935 * Returns: Always 0.
936 */
937static int watchdog_release(struct inode *inode, struct file *file)
938{
939 struct watchdog_core_data *wd_data = file->private_data;
940 struct watchdog_device *wdd;
941 int err = -EBUSY;
942 bool running;
943
944 mutex_lock(&wd_data->lock);
945
946 wdd = wd_data->wdd;
947 if (!wdd)
948 goto done;
949
950 /*
951 * We only stop the watchdog if we received the magic character
952 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
953 * watchdog_stop will fail.
954 */
955 if (!watchdog_active(wdd))
956 err = 0;
957 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
958 !(wdd->info->options & WDIOF_MAGICCLOSE))
959 err = watchdog_stop(wdd);
960
961 /* If the watchdog was not stopped, send a keepalive ping */
962 if (err < 0) {
963 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
964 watchdog_ping(wdd);
965 }
966
967 watchdog_update_worker(wdd);
968
969 /* make sure that /dev/watchdog can be re-opened */
970 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
971
972done:
973 running = wdd && watchdog_hw_running(wdd);
974 mutex_unlock(&wd_data->lock);
975 /*
976 * Allow the owner module to be unloaded again unless the watchdog
977 * is still running. If the watchdog is still running, it can not
978 * be stopped, and its driver must not be unloaded.
979 */
980 if (!running) {
981 module_put(wd_data->cdev.owner);
982 put_device(&wd_data->dev);
983 }
984 return 0;
985}
986
987static const struct file_operations watchdog_fops = {
988 .owner = THIS_MODULE,
989 .write = watchdog_write,
990 .unlocked_ioctl = watchdog_ioctl,
991 .compat_ioctl = compat_ptr_ioctl,
992 .open = watchdog_open,
993 .release = watchdog_release,
994};
995
996static struct miscdevice watchdog_miscdev = {
997 .minor = WATCHDOG_MINOR,
998 .name = "watchdog",
999 .fops = &watchdog_fops,
1000};
1001
1002static const struct class watchdog_class = {
1003 .name = "watchdog",
1004 .dev_groups = wdt_groups,
1005};
1006
1007/**
1008 * watchdog_cdev_register - register watchdog character device
1009 * @wdd: Watchdog device
1010 *
1011 * Register a watchdog character device including handling the legacy
1012 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1013 * thus we set it up like that.
1014 *
1015 * Return: 0 if successful, error otherwise.
1016 */
1017static int watchdog_cdev_register(struct watchdog_device *wdd)
1018{
1019 struct watchdog_core_data *wd_data;
1020 int err;
1021
1022 wd_data = kzalloc_obj(struct watchdog_core_data);
1023 if (!wd_data)
1024 return -ENOMEM;
1025 mutex_init(&wd_data->lock);
1026
1027 wd_data->wdd = wdd;
1028 wdd->wd_data = wd_data;
1029
1030 if (IS_ERR_OR_NULL(watchdog_kworker)) {
1031 kfree(wd_data);
1032 return -ENODEV;
1033 }
1034
1035 device_initialize(&wd_data->dev);
1036 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
1037 wd_data->dev.class = &watchdog_class;
1038 wd_data->dev.parent = wdd->parent;
1039 wd_data->dev.groups = wdd->groups;
1040 wd_data->dev.release = watchdog_core_data_release;
1041 dev_set_drvdata(&wd_data->dev, wdd);
1042 err = dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
1043 if (err) {
1044 put_device(&wd_data->dev);
1045 return err;
1046 }
1047
1048 kthread_init_work(&wd_data->work, watchdog_ping_work);
1049 hrtimer_setup(&wd_data->timer, watchdog_timer_expired, CLOCK_MONOTONIC,
1050 HRTIMER_MODE_REL_HARD);
1051 watchdog_hrtimer_pretimeout_init(wdd);
1052
1053 if (wdd->id == 0) {
1054 old_wd_data = wd_data;
1055 watchdog_miscdev.parent = wdd->parent;
1056 err = misc_register(&watchdog_miscdev);
1057 if (err != 0) {
1058 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
1059 wdd->info->identity, WATCHDOG_MINOR, err);
1060 if (err == -EBUSY)
1061 pr_err("%s: a legacy watchdog module is probably present.\n",
1062 wdd->info->identity);
1063 old_wd_data = NULL;
1064 put_device(&wd_data->dev);
1065 return err;
1066 }
1067 }
1068
1069 /* Fill in the data structures */
1070 cdev_init(&wd_data->cdev, &watchdog_fops);
1071 wd_data->cdev.owner = wdd->ops->owner;
1072
1073 /* Add the device */
1074 err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
1075 if (err) {
1076 pr_err("watchdog%d unable to add device %d:%d\n",
1077 wdd->id, MAJOR(watchdog_devt), wdd->id);
1078 if (wdd->id == 0) {
1079 misc_deregister(&watchdog_miscdev);
1080 old_wd_data = NULL;
1081 }
1082 put_device(&wd_data->dev);
1083 return err;
1084 }
1085
1086 /* Record time of most recent heartbeat as 'just before now'. */
1087 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
1088 watchdog_set_open_deadline(wd_data);
1089
1090 /*
1091 * If the watchdog is running, prevent its driver from being unloaded,
1092 * and schedule an immediate ping.
1093 */
1094 if (watchdog_hw_running(wdd)) {
1095 __module_get(wdd->ops->owner);
1096 get_device(&wd_data->dev);
1097 if (handle_boot_enabled)
1098 hrtimer_start(&wd_data->timer, 0,
1099 HRTIMER_MODE_REL_HARD);
1100 else
1101 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
1102 wdd->id);
1103 }
1104
1105 return 0;
1106}
1107
1108/**
1109 * watchdog_cdev_unregister - unregister watchdog character device
1110 * @wdd: Watchdog device
1111 *
1112 * Unregister watchdog character device and if needed the legacy
1113 * /dev/watchdog device.
1114 */
1115static void watchdog_cdev_unregister(struct watchdog_device *wdd)
1116{
1117 struct watchdog_core_data *wd_data = wdd->wd_data;
1118
1119 cdev_device_del(&wd_data->cdev, &wd_data->dev);
1120 if (wdd->id == 0) {
1121 misc_deregister(&watchdog_miscdev);
1122 old_wd_data = NULL;
1123 }
1124
1125 if (watchdog_active(wdd) &&
1126 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
1127 watchdog_stop(wdd);
1128 }
1129
1130 watchdog_hrtimer_pretimeout_stop(wdd);
1131
1132 mutex_lock(&wd_data->lock);
1133 wd_data->wdd = NULL;
1134 wdd->wd_data = NULL;
1135 mutex_unlock(&wd_data->lock);
1136
1137 hrtimer_cancel(&wd_data->timer);
1138 kthread_cancel_work_sync(&wd_data->work);
1139
1140 put_device(&wd_data->dev);
1141}
1142
1143/**
1144 * watchdog_dev_register - register a watchdog device
1145 * @wdd: Watchdog device
1146 *
1147 * Register a watchdog device including handling the legacy
1148 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1149 * thus we set it up like that.
1150 *
1151 * Return: 0 if successful, error otherwise.
1152 */
1153int watchdog_dev_register(struct watchdog_device *wdd)
1154{
1155 int ret;
1156
1157 ret = watchdog_cdev_register(wdd);
1158 if (ret)
1159 return ret;
1160
1161 ret = watchdog_register_pretimeout(wdd);
1162 if (ret)
1163 watchdog_cdev_unregister(wdd);
1164
1165 return ret;
1166}
1167
1168/**
1169 * watchdog_dev_unregister - unregister a watchdog device
1170 * @wdd: watchdog device
1171 *
1172 * Unregister watchdog device and if needed the legacy
1173 * /dev/watchdog device.
1174 */
1175void watchdog_dev_unregister(struct watchdog_device *wdd)
1176{
1177 watchdog_unregister_pretimeout(wdd);
1178 watchdog_cdev_unregister(wdd);
1179}
1180
1181/**
1182 * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
1183 * @wdd: Watchdog device
1184 * @last_ping_ms: Time since last HW heartbeat
1185 *
1186 * Adjusts the last known HW keepalive time for a watchdog timer.
1187 * This is needed if the watchdog is already running when the probe
1188 * function is called, and it can't be pinged immediately. This
1189 * function must be called immediately after watchdog registration,
1190 * and min_hw_heartbeat_ms must be set for this to be useful.
1191 *
1192 * Return: 0 if successful, error otherwise.
1193 */
1194int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
1195 unsigned int last_ping_ms)
1196{
1197 struct watchdog_core_data *wd_data;
1198 ktime_t now;
1199
1200 if (!wdd)
1201 return -EINVAL;
1202
1203 wd_data = wdd->wd_data;
1204
1205 now = ktime_get();
1206
1207 wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
1208
1209 if (watchdog_hw_running(wdd) && handle_boot_enabled)
1210 return __watchdog_ping(wdd);
1211
1212 return 0;
1213}
1214EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
1215
1216/**
1217 * watchdog_dev_init - init dev part of watchdog core
1218 *
1219 * Allocate a range of chardev nodes to use for watchdog devices.
1220 *
1221 * Return: 0 if successful, error otherwise.
1222 */
1223int __init watchdog_dev_init(void)
1224{
1225 int err;
1226
1227 watchdog_kworker = kthread_run_worker(0, "watchdogd");
1228 if (IS_ERR(watchdog_kworker)) {
1229 pr_err("Failed to create watchdog kworker\n");
1230 return PTR_ERR(watchdog_kworker);
1231 }
1232 sched_set_fifo(watchdog_kworker->task);
1233
1234 err = class_register(&watchdog_class);
1235 if (err < 0) {
1236 pr_err("couldn't register class\n");
1237 goto err_register;
1238 }
1239
1240 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1241 if (err < 0) {
1242 pr_err("watchdog: unable to allocate char dev region\n");
1243 goto err_alloc;
1244 }
1245
1246 return 0;
1247
1248err_alloc:
1249 class_unregister(&watchdog_class);
1250err_register:
1251 kthread_destroy_worker(watchdog_kworker);
1252 return err;
1253}
1254
1255/**
1256 * watchdog_dev_exit - exit dev part of watchdog core
1257 *
1258 * Release the range of chardev nodes used for watchdog devices.
1259 */
1260void __exit watchdog_dev_exit(void)
1261{
1262 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1263 class_unregister(&watchdog_class);
1264 kthread_destroy_worker(watchdog_kworker);
1265}
1266
1267int watchdog_dev_suspend(struct watchdog_device *wdd)
1268{
1269 struct watchdog_core_data *wd_data = wdd->wd_data;
1270 int ret = 0;
1271
1272 if (!wdd->wd_data)
1273 return -ENODEV;
1274
1275 /* ping for the last time before suspend */
1276 mutex_lock(&wd_data->lock);
1277 if (watchdog_worker_should_ping(wd_data))
1278 ret = __watchdog_ping(wd_data->wdd);
1279 mutex_unlock(&wd_data->lock);
1280
1281 if (ret)
1282 return ret;
1283
1284 /*
1285 * make sure that watchdog worker will not kick in when the wdog is
1286 * suspended
1287 */
1288 hrtimer_cancel(&wd_data->timer);
1289 kthread_cancel_work_sync(&wd_data->work);
1290
1291 return 0;
1292}
1293
1294int watchdog_dev_resume(struct watchdog_device *wdd)
1295{
1296 struct watchdog_core_data *wd_data = wdd->wd_data;
1297 int ret = 0;
1298
1299 if (!wdd->wd_data)
1300 return -ENODEV;
1301
1302 /*
1303 * __watchdog_ping will also retrigger hrtimer and therefore restore the
1304 * ping worker if needed.
1305 */
1306 mutex_lock(&wd_data->lock);
1307 if (watchdog_worker_should_ping(wd_data))
1308 ret = __watchdog_ping(wd_data->wdd);
1309 mutex_unlock(&wd_data->lock);
1310
1311 return ret;
1312}
1313
1314module_param(handle_boot_enabled, bool, 0444);
1315MODULE_PARM_DESC(handle_boot_enabled,
1316 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1317 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");
1318
1319module_param(open_timeout, uint, 0644);
1320MODULE_PARM_DESC(open_timeout,
1321 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
1322 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");