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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/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 *
428 * Return: 0 if successful, error otherwise.
429 */
430static int watchdog_get_timeleft(struct watchdog_device *wdd,
431 unsigned int *timeleft)
432{
433 *timeleft = 0;
434
435 if (!wdd->ops->get_timeleft)
436 return -EOPNOTSUPP;
437
438 *timeleft = wdd->ops->get_timeleft(wdd);
439
440 return 0;
441}
442
443#ifdef CONFIG_WATCHDOG_SYSFS
444static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
445 char *buf)
446{
447 struct watchdog_device *wdd = dev_get_drvdata(dev);
448
449 return sysfs_emit(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT,
450 &wdd->status));
451}
452
453static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,
454 const char *buf, size_t len)
455{
456 struct watchdog_device *wdd = dev_get_drvdata(dev);
457 unsigned int value;
458 int ret;
459
460 ret = kstrtouint(buf, 0, &value);
461 if (ret)
462 return ret;
463 if (value > 1)
464 return -EINVAL;
465 /* nowayout cannot be disabled once set */
466 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)
467 return -EPERM;
468 watchdog_set_nowayout(wdd, value);
469 return len;
470}
471static DEVICE_ATTR_RW(nowayout);
472
473static ssize_t status_show(struct device *dev, struct device_attribute *attr,
474 char *buf)
475{
476 struct watchdog_device *wdd = dev_get_drvdata(dev);
477 struct watchdog_core_data *wd_data = wdd->wd_data;
478 unsigned int status;
479
480 mutex_lock(&wd_data->lock);
481 status = watchdog_get_status(wdd);
482 mutex_unlock(&wd_data->lock);
483
484 return sysfs_emit(buf, "0x%x\n", status);
485}
486static DEVICE_ATTR_RO(status);
487
488static ssize_t bootstatus_show(struct device *dev,
489 struct device_attribute *attr, char *buf)
490{
491 struct watchdog_device *wdd = dev_get_drvdata(dev);
492
493 return sysfs_emit(buf, "%u\n", wdd->bootstatus);
494}
495static DEVICE_ATTR_RO(bootstatus);
496
497static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
498 char *buf)
499{
500 struct watchdog_device *wdd = dev_get_drvdata(dev);
501 struct watchdog_core_data *wd_data = wdd->wd_data;
502 ssize_t status;
503 unsigned int val;
504
505 mutex_lock(&wd_data->lock);
506 status = watchdog_get_timeleft(wdd, &val);
507 mutex_unlock(&wd_data->lock);
508 if (!status)
509 status = sysfs_emit(buf, "%u\n", val);
510
511 return status;
512}
513static DEVICE_ATTR_RO(timeleft);
514
515static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
516 char *buf)
517{
518 struct watchdog_device *wdd = dev_get_drvdata(dev);
519
520 return sysfs_emit(buf, "%u\n", wdd->timeout);
521}
522static DEVICE_ATTR_RO(timeout);
523
524static ssize_t min_timeout_show(struct device *dev,
525 struct device_attribute *attr, char *buf)
526{
527 struct watchdog_device *wdd = dev_get_drvdata(dev);
528
529 return sysfs_emit(buf, "%u\n", wdd->min_timeout);
530}
531static DEVICE_ATTR_RO(min_timeout);
532
533static ssize_t max_timeout_show(struct device *dev,
534 struct device_attribute *attr, char *buf)
535{
536 struct watchdog_device *wdd = dev_get_drvdata(dev);
537
538 return sysfs_emit(buf, "%u\n", wdd->max_timeout);
539}
540static DEVICE_ATTR_RO(max_timeout);
541
542static ssize_t pretimeout_show(struct device *dev,
543 struct device_attribute *attr, char *buf)
544{
545 struct watchdog_device *wdd = dev_get_drvdata(dev);
546
547 return sysfs_emit(buf, "%u\n", wdd->pretimeout);
548}
549static DEVICE_ATTR_RO(pretimeout);
550
551static ssize_t options_show(struct device *dev, struct device_attribute *attr,
552 char *buf)
553{
554 struct watchdog_device *wdd = dev_get_drvdata(dev);
555
556 return sysfs_emit(buf, "0x%x\n", wdd->info->options);
557}
558static DEVICE_ATTR_RO(options);
559
560static ssize_t fw_version_show(struct device *dev, struct device_attribute *attr,
561 char *buf)
562{
563 struct watchdog_device *wdd = dev_get_drvdata(dev);
564
565 return sysfs_emit(buf, "%d\n", wdd->info->firmware_version);
566}
567static DEVICE_ATTR_RO(fw_version);
568
569static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
570 char *buf)
571{
572 struct watchdog_device *wdd = dev_get_drvdata(dev);
573
574 return sysfs_emit(buf, "%s\n", wdd->info->identity);
575}
576static DEVICE_ATTR_RO(identity);
577
578static ssize_t state_show(struct device *dev, struct device_attribute *attr,
579 char *buf)
580{
581 struct watchdog_device *wdd = dev_get_drvdata(dev);
582
583 if (watchdog_active(wdd))
584 return sysfs_emit(buf, "active\n");
585
586 return sysfs_emit(buf, "inactive\n");
587}
588static DEVICE_ATTR_RO(state);
589
590static ssize_t pretimeout_available_governors_show(struct device *dev,
591 struct device_attribute *attr, char *buf)
592{
593 return watchdog_pretimeout_available_governors_get(buf);
594}
595static DEVICE_ATTR_RO(pretimeout_available_governors);
596
597static ssize_t pretimeout_governor_show(struct device *dev,
598 struct device_attribute *attr,
599 char *buf)
600{
601 struct watchdog_device *wdd = dev_get_drvdata(dev);
602
603 return watchdog_pretimeout_governor_get(wdd, buf);
604}
605
606static ssize_t pretimeout_governor_store(struct device *dev,
607 struct device_attribute *attr,
608 const char *buf, size_t count)
609{
610 struct watchdog_device *wdd = dev_get_drvdata(dev);
611 int ret = watchdog_pretimeout_governor_set(wdd, buf);
612
613 if (!ret)
614 ret = count;
615
616 return ret;
617}
618static DEVICE_ATTR_RW(pretimeout_governor);
619
620static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
621 int n)
622{
623 struct device *dev = kobj_to_dev(kobj);
624 struct watchdog_device *wdd = dev_get_drvdata(dev);
625 umode_t mode = attr->mode;
626
627 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
628 mode = 0;
629 else if (attr == &dev_attr_pretimeout.attr && !watchdog_have_pretimeout(wdd))
630 mode = 0;
631 else if ((attr == &dev_attr_pretimeout_governor.attr ||
632 attr == &dev_attr_pretimeout_available_governors.attr) &&
633 (!watchdog_have_pretimeout(wdd) || !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
634 mode = 0;
635
636 return mode;
637}
638static struct attribute *wdt_attrs[] = {
639 &dev_attr_state.attr,
640 &dev_attr_options.attr,
641 &dev_attr_fw_version.attr,
642 &dev_attr_identity.attr,
643 &dev_attr_timeout.attr,
644 &dev_attr_min_timeout.attr,
645 &dev_attr_max_timeout.attr,
646 &dev_attr_pretimeout.attr,
647 &dev_attr_timeleft.attr,
648 &dev_attr_bootstatus.attr,
649 &dev_attr_status.attr,
650 &dev_attr_nowayout.attr,
651 &dev_attr_pretimeout_governor.attr,
652 &dev_attr_pretimeout_available_governors.attr,
653 NULL,
654};
655
656static const struct attribute_group wdt_group = {
657 .attrs = wdt_attrs,
658 .is_visible = wdt_is_visible,
659};
660__ATTRIBUTE_GROUPS(wdt);
661#else
662#define wdt_groups NULL
663#endif
664
665/*
666 * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
667 * @wdd: The watchdog device to do the ioctl on
668 * @cmd: Watchdog command
669 * @arg: Argument pointer
670 *
671 * The caller must hold wd_data->lock.
672 *
673 * Return: 0 if successful, error otherwise.
674 */
675static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
676 unsigned long arg)
677{
678 if (!wdd->ops->ioctl)
679 return -ENOIOCTLCMD;
680
681 return wdd->ops->ioctl(wdd, cmd, arg);
682}
683
684/*
685 * watchdog_write - writes to the watchdog
686 * @file: File from VFS
687 * @data: User address of data
688 * @len: Length of data
689 * @ppos: Pointer to the file offset
690 *
691 * A write to a watchdog device is defined as a keepalive ping.
692 * Writing the magic 'V' sequence allows the next close to turn
693 * off the watchdog (if 'nowayout' is not set).
694 *
695 * Return: @len if successful, error otherwise.
696 */
697static ssize_t watchdog_write(struct file *file, const char __user *data,
698 size_t len, loff_t *ppos)
699{
700 struct watchdog_core_data *wd_data = file->private_data;
701 struct watchdog_device *wdd;
702 int err;
703 size_t i;
704 char c;
705
706 if (len == 0)
707 return 0;
708
709 /*
710 * Note: just in case someone wrote the magic character
711 * five months ago...
712 */
713 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
714
715 /* scan to see whether or not we got the magic character */
716 for (i = 0; i != len; i++) {
717 if (get_user(c, data + i))
718 return -EFAULT;
719 if (c == 'V')
720 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
721 }
722
723 /* someone wrote to us, so we send the watchdog a keepalive ping */
724
725 err = -ENODEV;
726 mutex_lock(&wd_data->lock);
727 wdd = wd_data->wdd;
728 if (wdd)
729 err = watchdog_ping(wdd);
730 mutex_unlock(&wd_data->lock);
731
732 if (err < 0)
733 return err;
734
735 return len;
736}
737
738/*
739 * watchdog_ioctl - handle the different ioctl's for the watchdog device
740 * @file: File handle to the device
741 * @cmd: Watchdog command
742 * @arg: Argument pointer
743 *
744 * The watchdog API defines a common set of functions for all watchdogs
745 * according to their available features.
746 *
747 * Return: 0 if successful, error otherwise.
748 */
749
750static long watchdog_ioctl(struct file *file, unsigned int cmd,
751 unsigned long arg)
752{
753 struct watchdog_core_data *wd_data = file->private_data;
754 void __user *argp = (void __user *)arg;
755 struct watchdog_device *wdd;
756 int __user *p = argp;
757 unsigned int val;
758 int err;
759
760 mutex_lock(&wd_data->lock);
761
762 wdd = wd_data->wdd;
763 if (!wdd) {
764 err = -ENODEV;
765 goto out_ioctl;
766 }
767
768 err = watchdog_ioctl_op(wdd, cmd, arg);
769 if (err != -ENOIOCTLCMD)
770 goto out_ioctl;
771
772 switch (cmd) {
773 case WDIOC_GETSUPPORT:
774 err = copy_to_user(argp, wdd->info,
775 sizeof(struct watchdog_info)) ? -EFAULT : 0;
776 break;
777 case WDIOC_GETSTATUS:
778 val = watchdog_get_status(wdd);
779 err = put_user(val, p);
780 break;
781 case WDIOC_GETBOOTSTATUS:
782 err = put_user(wdd->bootstatus, p);
783 break;
784 case WDIOC_SETOPTIONS:
785 if (get_user(val, p)) {
786 err = -EFAULT;
787 break;
788 }
789 if (val & WDIOS_DISABLECARD) {
790 err = watchdog_stop(wdd);
791 if (err < 0)
792 break;
793 }
794 if (val & WDIOS_ENABLECARD)
795 err = watchdog_start(wdd);
796 break;
797 case WDIOC_KEEPALIVE:
798 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
799 err = -EOPNOTSUPP;
800 break;
801 }
802 err = watchdog_ping(wdd);
803 break;
804 case WDIOC_SETTIMEOUT:
805 if (get_user(val, p)) {
806 err = -EFAULT;
807 break;
808 }
809 err = watchdog_set_timeout(wdd, val);
810 if (err < 0)
811 break;
812 /* If the watchdog is active then we send a keepalive ping
813 * to make sure that the watchdog keep's running (and if
814 * possible that it takes the new timeout) */
815 err = watchdog_ping(wdd);
816 if (err < 0)
817 break;
818 fallthrough;
819 case WDIOC_GETTIMEOUT:
820 /* timeout == 0 means that we don't know the timeout */
821 if (wdd->timeout == 0) {
822 err = -EOPNOTSUPP;
823 break;
824 }
825 err = put_user(wdd->timeout, p);
826 break;
827 case WDIOC_GETTIMELEFT:
828 err = watchdog_get_timeleft(wdd, &val);
829 if (err < 0)
830 break;
831 err = put_user(val, p);
832 break;
833 case WDIOC_SETPRETIMEOUT:
834 if (get_user(val, p)) {
835 err = -EFAULT;
836 break;
837 }
838 err = watchdog_set_pretimeout(wdd, val);
839 break;
840 case WDIOC_GETPRETIMEOUT:
841 err = put_user(wdd->pretimeout, p);
842 break;
843 default:
844 err = -ENOTTY;
845 break;
846 }
847
848out_ioctl:
849 mutex_unlock(&wd_data->lock);
850 return err;
851}
852
853/*
854 * watchdog_open - open the /dev/watchdog* devices
855 * @inode: Inode of device
856 * @file: File handle to device
857 *
858 * When the /dev/watchdog* device gets opened, we start the watchdog.
859 * Watch out: the /dev/watchdog device is single open, so we make sure
860 * it can only be opened once.
861 *
862 * Return: 0 if successful, error otherwise.
863 */
864static int watchdog_open(struct inode *inode, struct file *file)
865{
866 struct watchdog_core_data *wd_data;
867 struct watchdog_device *wdd;
868 bool hw_running;
869 int err;
870
871 /* Get the corresponding watchdog device */
872 if (imajor(inode) == MISC_MAJOR)
873 wd_data = old_wd_data;
874 else
875 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
876 cdev);
877
878 /* the watchdog is single open! */
879 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
880 return -EBUSY;
881
882 wdd = wd_data->wdd;
883
884 /*
885 * If the /dev/watchdog device is open, we don't want the module
886 * to be unloaded.
887 */
888 hw_running = watchdog_hw_running(wdd);
889 if (!hw_running && !try_module_get(wdd->ops->owner)) {
890 err = -EBUSY;
891 goto out_clear;
892 }
893
894 err = watchdog_start(wdd);
895 if (err < 0)
896 goto out_mod;
897
898 file->private_data = wd_data;
899
900 if (!hw_running)
901 get_device(&wd_data->dev);
902
903 /*
904 * open_timeout only applies for the first open from
905 * userspace. Set open_deadline to infinity so that the kernel
906 * will take care of an always-running hardware watchdog in
907 * case the device gets magic-closed or WDIOS_DISABLECARD is
908 * applied.
909 */
910 wd_data->open_deadline = KTIME_MAX;
911
912 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
913 return stream_open(inode, file);
914
915out_mod:
916 module_put(wd_data->wdd->ops->owner);
917out_clear:
918 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
919 return err;
920}
921
922static void watchdog_core_data_release(struct device *dev)
923{
924 struct watchdog_core_data *wd_data;
925
926 wd_data = container_of(dev, struct watchdog_core_data, dev);
927
928 kfree(wd_data);
929}
930
931/*
932 * watchdog_release - release the watchdog device
933 * @inode: Inode of device
934 * @file: File handle to device
935 *
936 * This is the code for when /dev/watchdog gets closed. We will only
937 * stop the watchdog when we have received the magic char (and nowayout
938 * was not set), else the watchdog will keep running.
939 *
940 * Always returns 0.
941 */
942static int watchdog_release(struct inode *inode, struct file *file)
943{
944 struct watchdog_core_data *wd_data = file->private_data;
945 struct watchdog_device *wdd;
946 int err = -EBUSY;
947 bool running;
948
949 mutex_lock(&wd_data->lock);
950
951 wdd = wd_data->wdd;
952 if (!wdd)
953 goto done;
954
955 /*
956 * We only stop the watchdog if we received the magic character
957 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
958 * watchdog_stop will fail.
959 */
960 if (!watchdog_active(wdd))
961 err = 0;
962 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
963 !(wdd->info->options & WDIOF_MAGICCLOSE))
964 err = watchdog_stop(wdd);
965
966 /* If the watchdog was not stopped, send a keepalive ping */
967 if (err < 0) {
968 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
969 watchdog_ping(wdd);
970 }
971
972 watchdog_update_worker(wdd);
973
974 /* make sure that /dev/watchdog can be re-opened */
975 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
976
977done:
978 running = wdd && watchdog_hw_running(wdd);
979 mutex_unlock(&wd_data->lock);
980 /*
981 * Allow the owner module to be unloaded again unless the watchdog
982 * is still running. If the watchdog is still running, it can not
983 * be stopped, and its driver must not be unloaded.
984 */
985 if (!running) {
986 module_put(wd_data->cdev.owner);
987 put_device(&wd_data->dev);
988 }
989 return 0;
990}
991
992static const struct file_operations watchdog_fops = {
993 .owner = THIS_MODULE,
994 .write = watchdog_write,
995 .unlocked_ioctl = watchdog_ioctl,
996 .compat_ioctl = compat_ptr_ioctl,
997 .open = watchdog_open,
998 .release = watchdog_release,
999};
1000
1001static struct miscdevice watchdog_miscdev = {
1002 .minor = WATCHDOG_MINOR,
1003 .name = "watchdog",
1004 .fops = &watchdog_fops,
1005};
1006
1007static const struct class watchdog_class = {
1008 .name = "watchdog",
1009 .dev_groups = wdt_groups,
1010};
1011
1012/*
1013 * watchdog_cdev_register - register watchdog character device
1014 * @wdd: Watchdog device
1015 *
1016 * Register a watchdog character device including handling the legacy
1017 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1018 * thus we set it up like that.
1019 *
1020 * Return: 0 if successful, error otherwise.
1021 */
1022static int watchdog_cdev_register(struct watchdog_device *wdd)
1023{
1024 struct watchdog_core_data *wd_data;
1025 int err;
1026
1027 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
1028 if (!wd_data)
1029 return -ENOMEM;
1030 mutex_init(&wd_data->lock);
1031
1032 wd_data->wdd = wdd;
1033 wdd->wd_data = wd_data;
1034
1035 if (IS_ERR_OR_NULL(watchdog_kworker)) {
1036 kfree(wd_data);
1037 return -ENODEV;
1038 }
1039
1040 device_initialize(&wd_data->dev);
1041 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
1042 wd_data->dev.class = &watchdog_class;
1043 wd_data->dev.parent = wdd->parent;
1044 wd_data->dev.groups = wdd->groups;
1045 wd_data->dev.release = watchdog_core_data_release;
1046 dev_set_drvdata(&wd_data->dev, wdd);
1047 err = dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
1048 if (err) {
1049 put_device(&wd_data->dev);
1050 return err;
1051 }
1052
1053 kthread_init_work(&wd_data->work, watchdog_ping_work);
1054 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1055 wd_data->timer.function = watchdog_timer_expired;
1056 watchdog_hrtimer_pretimeout_init(wdd);
1057
1058 if (wdd->id == 0) {
1059 old_wd_data = wd_data;
1060 watchdog_miscdev.parent = wdd->parent;
1061 err = misc_register(&watchdog_miscdev);
1062 if (err != 0) {
1063 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
1064 wdd->info->identity, WATCHDOG_MINOR, err);
1065 if (err == -EBUSY)
1066 pr_err("%s: a legacy watchdog module is probably present.\n",
1067 wdd->info->identity);
1068 old_wd_data = NULL;
1069 put_device(&wd_data->dev);
1070 return err;
1071 }
1072 }
1073
1074 /* Fill in the data structures */
1075 cdev_init(&wd_data->cdev, &watchdog_fops);
1076 wd_data->cdev.owner = wdd->ops->owner;
1077
1078 /* Add the device */
1079 err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
1080 if (err) {
1081 pr_err("watchdog%d unable to add device %d:%d\n",
1082 wdd->id, MAJOR(watchdog_devt), wdd->id);
1083 if (wdd->id == 0) {
1084 misc_deregister(&watchdog_miscdev);
1085 old_wd_data = NULL;
1086 }
1087 put_device(&wd_data->dev);
1088 return err;
1089 }
1090
1091 /* Record time of most recent heartbeat as 'just before now'. */
1092 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
1093 watchdog_set_open_deadline(wd_data);
1094
1095 /*
1096 * If the watchdog is running, prevent its driver from being unloaded,
1097 * and schedule an immediate ping.
1098 */
1099 if (watchdog_hw_running(wdd)) {
1100 __module_get(wdd->ops->owner);
1101 get_device(&wd_data->dev);
1102 if (handle_boot_enabled)
1103 hrtimer_start(&wd_data->timer, 0,
1104 HRTIMER_MODE_REL_HARD);
1105 else
1106 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
1107 wdd->id);
1108 }
1109
1110 return 0;
1111}
1112
1113/*
1114 * watchdog_cdev_unregister - unregister watchdog character device
1115 * @wdd: Watchdog device
1116 *
1117 * Unregister watchdog character device and if needed the legacy
1118 * /dev/watchdog device.
1119 */
1120static void watchdog_cdev_unregister(struct watchdog_device *wdd)
1121{
1122 struct watchdog_core_data *wd_data = wdd->wd_data;
1123
1124 cdev_device_del(&wd_data->cdev, &wd_data->dev);
1125 if (wdd->id == 0) {
1126 misc_deregister(&watchdog_miscdev);
1127 old_wd_data = NULL;
1128 }
1129
1130 if (watchdog_active(wdd) &&
1131 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
1132 watchdog_stop(wdd);
1133 }
1134
1135 watchdog_hrtimer_pretimeout_stop(wdd);
1136
1137 mutex_lock(&wd_data->lock);
1138 wd_data->wdd = NULL;
1139 wdd->wd_data = NULL;
1140 mutex_unlock(&wd_data->lock);
1141
1142 hrtimer_cancel(&wd_data->timer);
1143 kthread_cancel_work_sync(&wd_data->work);
1144
1145 put_device(&wd_data->dev);
1146}
1147
1148/**
1149 * watchdog_dev_register - register a watchdog device
1150 * @wdd: Watchdog device
1151 *
1152 * Register a watchdog device including handling the legacy
1153 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1154 * thus we set it up like that.
1155 *
1156 * Return: 0 if successful, error otherwise.
1157 */
1158int watchdog_dev_register(struct watchdog_device *wdd)
1159{
1160 int ret;
1161
1162 ret = watchdog_cdev_register(wdd);
1163 if (ret)
1164 return ret;
1165
1166 ret = watchdog_register_pretimeout(wdd);
1167 if (ret)
1168 watchdog_cdev_unregister(wdd);
1169
1170 return ret;
1171}
1172
1173/**
1174 * watchdog_dev_unregister - unregister a watchdog device
1175 * @wdd: watchdog device
1176 *
1177 * Unregister watchdog device and if needed the legacy
1178 * /dev/watchdog device.
1179 */
1180void watchdog_dev_unregister(struct watchdog_device *wdd)
1181{
1182 watchdog_unregister_pretimeout(wdd);
1183 watchdog_cdev_unregister(wdd);
1184}
1185
1186/**
1187 * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
1188 * @wdd: Watchdog device
1189 * @last_ping_ms: Time since last HW heartbeat
1190 *
1191 * Adjusts the last known HW keepalive time for a watchdog timer.
1192 * This is needed if the watchdog is already running when the probe
1193 * function is called, and it can't be pinged immediately. This
1194 * function must be called immediately after watchdog registration,
1195 * and min_hw_heartbeat_ms must be set for this to be useful.
1196 *
1197 * Return: 0 if successful, error otherwise.
1198 */
1199int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
1200 unsigned int last_ping_ms)
1201{
1202 struct watchdog_core_data *wd_data;
1203 ktime_t now;
1204
1205 if (!wdd)
1206 return -EINVAL;
1207
1208 wd_data = wdd->wd_data;
1209
1210 now = ktime_get();
1211
1212 wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
1213
1214 if (watchdog_hw_running(wdd) && handle_boot_enabled)
1215 return __watchdog_ping(wdd);
1216
1217 return 0;
1218}
1219EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
1220
1221/**
1222 * watchdog_dev_init - init dev part of watchdog core
1223 *
1224 * Allocate a range of chardev nodes to use for watchdog devices.
1225 *
1226 * Return: 0 if successful, error otherwise.
1227 */
1228int __init watchdog_dev_init(void)
1229{
1230 int err;
1231
1232 watchdog_kworker = kthread_create_worker(0, "watchdogd");
1233 if (IS_ERR(watchdog_kworker)) {
1234 pr_err("Failed to create watchdog kworker\n");
1235 return PTR_ERR(watchdog_kworker);
1236 }
1237 sched_set_fifo(watchdog_kworker->task);
1238
1239 err = class_register(&watchdog_class);
1240 if (err < 0) {
1241 pr_err("couldn't register class\n");
1242 goto err_register;
1243 }
1244
1245 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1246 if (err < 0) {
1247 pr_err("watchdog: unable to allocate char dev region\n");
1248 goto err_alloc;
1249 }
1250
1251 return 0;
1252
1253err_alloc:
1254 class_unregister(&watchdog_class);
1255err_register:
1256 kthread_destroy_worker(watchdog_kworker);
1257 return err;
1258}
1259
1260/**
1261 * watchdog_dev_exit - exit dev part of watchdog core
1262 *
1263 * Release the range of chardev nodes used for watchdog devices.
1264 */
1265void __exit watchdog_dev_exit(void)
1266{
1267 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1268 class_unregister(&watchdog_class);
1269 kthread_destroy_worker(watchdog_kworker);
1270}
1271
1272int watchdog_dev_suspend(struct watchdog_device *wdd)
1273{
1274 struct watchdog_core_data *wd_data = wdd->wd_data;
1275 int ret = 0;
1276
1277 if (!wdd->wd_data)
1278 return -ENODEV;
1279
1280 /* ping for the last time before suspend */
1281 mutex_lock(&wd_data->lock);
1282 if (watchdog_worker_should_ping(wd_data))
1283 ret = __watchdog_ping(wd_data->wdd);
1284 mutex_unlock(&wd_data->lock);
1285
1286 if (ret)
1287 return ret;
1288
1289 /*
1290 * make sure that watchdog worker will not kick in when the wdog is
1291 * suspended
1292 */
1293 hrtimer_cancel(&wd_data->timer);
1294 kthread_cancel_work_sync(&wd_data->work);
1295
1296 return 0;
1297}
1298
1299int watchdog_dev_resume(struct watchdog_device *wdd)
1300{
1301 struct watchdog_core_data *wd_data = wdd->wd_data;
1302 int ret = 0;
1303
1304 if (!wdd->wd_data)
1305 return -ENODEV;
1306
1307 /*
1308 * __watchdog_ping will also retrigger hrtimer and therefore restore the
1309 * ping worker if needed.
1310 */
1311 mutex_lock(&wd_data->lock);
1312 if (watchdog_worker_should_ping(wd_data))
1313 ret = __watchdog_ping(wd_data->wdd);
1314 mutex_unlock(&wd_data->lock);
1315
1316 return ret;
1317}
1318
1319module_param(handle_boot_enabled, bool, 0444);
1320MODULE_PARM_DESC(handle_boot_enabled,
1321 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1322 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");
1323
1324module_param(open_timeout, uint, 0644);
1325MODULE_PARM_DESC(open_timeout,
1326 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
1327 __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 * (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) ")");