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