4 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
7 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
10 * This source code is part of the generic code that can be used
11 * by all the watchdog timer drivers.
13 * This part of the generic code takes care of the following
14 * misc device: /dev/watchdog.
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>
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.
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.
33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/kthread.h> /* For kthread_work */
42 #include <linux/miscdevice.h> /* For handling misc devices */
43 #include <linux/module.h> /* For module stuff/... */
44 #include <linux/mutex.h> /* For mutexes */
45 #include <linux/slab.h> /* For memory functions */
46 #include <linux/types.h> /* For standard types (like size_t) */
47 #include <linux/watchdog.h> /* For watchdog specific items */
48 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */
50 #include <uapi/linux/sched/types.h> /* For struct sched_param */
52 #include "watchdog_core.h"
53 #include "watchdog_pretimeout.h"
56 * struct watchdog_core_data - watchdog core internal data
57 * @dev: The watchdog's internal device
58 * @cdev: The watchdog's Character device.
59 * @wdd: Pointer to watchdog device.
60 * @lock: Lock for watchdog core.
61 * @status: Watchdog core internal status bits.
63 struct watchdog_core_data {
66 struct watchdog_device *wdd;
68 ktime_t last_keepalive;
69 ktime_t last_hw_keepalive;
71 struct kthread_work work;
72 unsigned long status; /* Internal status bits */
73 #define _WDOG_DEV_OPEN 0 /* Opened ? */
74 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
75 #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
78 /* the dev_t structure to store the dynamically allocated watchdog devices */
79 static dev_t watchdog_devt;
80 /* Reference to watchdog device behind /dev/watchdog */
81 static struct watchdog_core_data *old_wd_data;
83 static struct kthread_worker *watchdog_kworker;
85 static bool handle_boot_enabled =
86 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
88 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
90 /* All variables in milli-seconds */
91 unsigned int hm = wdd->max_hw_heartbeat_ms;
92 unsigned int t = wdd->timeout * 1000;
95 * A worker to generate heartbeat requests is needed if all of the
96 * following conditions are true.
97 * - Userspace activated the watchdog.
98 * - The driver provided a value for the maximum hardware timeout, and
99 * thus is aware that the framework supports generating heartbeat
101 * - Userspace requests a longer timeout than the hardware can handle.
103 * Alternatively, if userspace has not opened the watchdog
104 * device, we take care of feeding the watchdog if it is
107 return (hm && watchdog_active(wdd) && t > hm) ||
108 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
111 static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
113 struct watchdog_core_data *wd_data = wdd->wd_data;
114 unsigned int timeout_ms = wdd->timeout * 1000;
115 ktime_t keepalive_interval;
116 ktime_t last_heartbeat, latest_heartbeat;
117 ktime_t virt_timeout;
118 unsigned int hw_heartbeat_ms;
120 virt_timeout = ktime_add(wd_data->last_keepalive,
121 ms_to_ktime(timeout_ms));
122 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
123 keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
125 if (!watchdog_active(wdd))
126 return keepalive_interval;
129 * To ensure that the watchdog times out wdd->timeout seconds
130 * after the most recent ping from userspace, the last
131 * worker ping has to come in hw_heartbeat_ms before this timeout.
133 last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
134 latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
135 if (ktime_before(latest_heartbeat, keepalive_interval))
136 return latest_heartbeat;
137 return keepalive_interval;
140 static inline void watchdog_update_worker(struct watchdog_device *wdd)
142 struct watchdog_core_data *wd_data = wdd->wd_data;
144 if (watchdog_need_worker(wdd)) {
145 ktime_t t = watchdog_next_keepalive(wdd);
148 hrtimer_start(&wd_data->timer, t, HRTIMER_MODE_REL);
150 hrtimer_cancel(&wd_data->timer);
154 static int __watchdog_ping(struct watchdog_device *wdd)
156 struct watchdog_core_data *wd_data = wdd->wd_data;
157 ktime_t earliest_keepalive, now;
160 earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
161 ms_to_ktime(wdd->min_hw_heartbeat_ms));
164 if (ktime_after(earliest_keepalive, now)) {
165 hrtimer_start(&wd_data->timer,
166 ktime_sub(earliest_keepalive, now),
171 wd_data->last_hw_keepalive = now;
174 err = wdd->ops->ping(wdd); /* ping the watchdog */
176 err = wdd->ops->start(wdd); /* restart watchdog */
178 watchdog_update_worker(wdd);
184 * watchdog_ping: ping the watchdog.
185 * @wdd: the watchdog device to ping
187 * The caller must hold wd_data->lock.
189 * If the watchdog has no own ping operation then it needs to be
190 * restarted via the start operation. This wrapper function does
192 * We only ping when the watchdog device is running.
195 static int watchdog_ping(struct watchdog_device *wdd)
197 struct watchdog_core_data *wd_data = wdd->wd_data;
199 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
202 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
204 wd_data->last_keepalive = ktime_get();
205 return __watchdog_ping(wdd);
208 static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
210 struct watchdog_device *wdd = wd_data->wdd;
212 return wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd));
215 static void watchdog_ping_work(struct kthread_work *work)
217 struct watchdog_core_data *wd_data;
219 wd_data = container_of(work, struct watchdog_core_data, work);
221 mutex_lock(&wd_data->lock);
222 if (watchdog_worker_should_ping(wd_data))
223 __watchdog_ping(wd_data->wdd);
224 mutex_unlock(&wd_data->lock);
227 static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
229 struct watchdog_core_data *wd_data;
231 wd_data = container_of(timer, struct watchdog_core_data, timer);
233 kthread_queue_work(watchdog_kworker, &wd_data->work);
234 return HRTIMER_NORESTART;
238 * watchdog_start: wrapper to start the watchdog.
239 * @wdd: the watchdog device to start
241 * The caller must hold wd_data->lock.
243 * Start the watchdog if it is not active and mark it active.
244 * This function returns zero on success or a negative errno code for
248 static int watchdog_start(struct watchdog_device *wdd)
250 struct watchdog_core_data *wd_data = wdd->wd_data;
254 if (watchdog_active(wdd))
257 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
259 started_at = ktime_get();
260 if (watchdog_hw_running(wdd) && wdd->ops->ping)
261 err = wdd->ops->ping(wdd);
263 err = wdd->ops->start(wdd);
265 set_bit(WDOG_ACTIVE, &wdd->status);
266 wd_data->last_keepalive = started_at;
267 wd_data->last_hw_keepalive = started_at;
268 watchdog_update_worker(wdd);
275 * watchdog_stop: wrapper to stop the watchdog.
276 * @wdd: the watchdog device to stop
278 * The caller must hold wd_data->lock.
280 * Stop the watchdog if it is still active and unmark it active.
281 * This function returns zero on success or a negative errno code for
283 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
286 static int watchdog_stop(struct watchdog_device *wdd)
290 if (!watchdog_active(wdd))
293 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
294 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
299 if (wdd->ops->stop) {
300 clear_bit(WDOG_HW_RUNNING, &wdd->status);
301 err = wdd->ops->stop(wdd);
303 set_bit(WDOG_HW_RUNNING, &wdd->status);
307 clear_bit(WDOG_ACTIVE, &wdd->status);
308 watchdog_update_worker(wdd);
315 * watchdog_get_status: wrapper to get the watchdog status
316 * @wdd: the watchdog device to get the status from
318 * The caller must hold wd_data->lock.
320 * Get the watchdog's status flags.
323 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
325 struct watchdog_core_data *wd_data = wdd->wd_data;
328 if (wdd->ops->status)
329 status = wdd->ops->status(wdd);
331 status = wdd->bootstatus & (WDIOF_CARDRESET |
339 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
340 status |= WDIOF_MAGICCLOSE;
342 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
343 status |= WDIOF_KEEPALIVEPING;
349 * watchdog_set_timeout: set the watchdog timer timeout
350 * @wdd: the watchdog device to set the timeout for
351 * @timeout: timeout to set in seconds
353 * The caller must hold wd_data->lock.
356 static int watchdog_set_timeout(struct watchdog_device *wdd,
357 unsigned int timeout)
361 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
364 if (watchdog_timeout_invalid(wdd, timeout))
367 if (wdd->ops->set_timeout) {
368 err = wdd->ops->set_timeout(wdd, timeout);
370 wdd->timeout = timeout;
371 /* Disable pretimeout if it doesn't fit the new timeout */
372 if (wdd->pretimeout >= wdd->timeout)
376 watchdog_update_worker(wdd);
382 * watchdog_set_pretimeout: set the watchdog timer pretimeout
383 * @wdd: the watchdog device to set the timeout for
384 * @timeout: pretimeout to set in seconds
387 static int watchdog_set_pretimeout(struct watchdog_device *wdd,
388 unsigned int timeout)
392 if (!(wdd->info->options & WDIOF_PRETIMEOUT))
395 if (watchdog_pretimeout_invalid(wdd, timeout))
398 if (wdd->ops->set_pretimeout)
399 err = wdd->ops->set_pretimeout(wdd, timeout);
401 wdd->pretimeout = timeout;
407 * watchdog_get_timeleft: wrapper to get the time left before a reboot
408 * @wdd: the watchdog device to get the remaining time from
409 * @timeleft: the time that's left
411 * The caller must hold wd_data->lock.
413 * Get the time before a watchdog will reboot (if not pinged).
416 static int watchdog_get_timeleft(struct watchdog_device *wdd,
417 unsigned int *timeleft)
421 if (!wdd->ops->get_timeleft)
424 *timeleft = wdd->ops->get_timeleft(wdd);
429 #ifdef CONFIG_WATCHDOG_SYSFS
430 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
433 struct watchdog_device *wdd = dev_get_drvdata(dev);
435 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
437 static DEVICE_ATTR_RO(nowayout);
439 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
442 struct watchdog_device *wdd = dev_get_drvdata(dev);
443 struct watchdog_core_data *wd_data = wdd->wd_data;
446 mutex_lock(&wd_data->lock);
447 status = watchdog_get_status(wdd);
448 mutex_unlock(&wd_data->lock);
450 return sprintf(buf, "0x%x\n", status);
452 static DEVICE_ATTR_RO(status);
454 static ssize_t bootstatus_show(struct device *dev,
455 struct device_attribute *attr, char *buf)
457 struct watchdog_device *wdd = dev_get_drvdata(dev);
459 return sprintf(buf, "%u\n", wdd->bootstatus);
461 static DEVICE_ATTR_RO(bootstatus);
463 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
466 struct watchdog_device *wdd = dev_get_drvdata(dev);
467 struct watchdog_core_data *wd_data = wdd->wd_data;
471 mutex_lock(&wd_data->lock);
472 status = watchdog_get_timeleft(wdd, &val);
473 mutex_unlock(&wd_data->lock);
475 status = sprintf(buf, "%u\n", val);
479 static DEVICE_ATTR_RO(timeleft);
481 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
484 struct watchdog_device *wdd = dev_get_drvdata(dev);
486 return sprintf(buf, "%u\n", wdd->timeout);
488 static DEVICE_ATTR_RO(timeout);
490 static ssize_t pretimeout_show(struct device *dev,
491 struct device_attribute *attr, char *buf)
493 struct watchdog_device *wdd = dev_get_drvdata(dev);
495 return sprintf(buf, "%u\n", wdd->pretimeout);
497 static DEVICE_ATTR_RO(pretimeout);
499 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
502 struct watchdog_device *wdd = dev_get_drvdata(dev);
504 return sprintf(buf, "%s\n", wdd->info->identity);
506 static DEVICE_ATTR_RO(identity);
508 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
511 struct watchdog_device *wdd = dev_get_drvdata(dev);
513 if (watchdog_active(wdd))
514 return sprintf(buf, "active\n");
516 return sprintf(buf, "inactive\n");
518 static DEVICE_ATTR_RO(state);
520 static ssize_t pretimeout_available_governors_show(struct device *dev,
521 struct device_attribute *attr, char *buf)
523 return watchdog_pretimeout_available_governors_get(buf);
525 static DEVICE_ATTR_RO(pretimeout_available_governors);
527 static ssize_t pretimeout_governor_show(struct device *dev,
528 struct device_attribute *attr,
531 struct watchdog_device *wdd = dev_get_drvdata(dev);
533 return watchdog_pretimeout_governor_get(wdd, buf);
536 static ssize_t pretimeout_governor_store(struct device *dev,
537 struct device_attribute *attr,
538 const char *buf, size_t count)
540 struct watchdog_device *wdd = dev_get_drvdata(dev);
541 int ret = watchdog_pretimeout_governor_set(wdd, buf);
548 static DEVICE_ATTR_RW(pretimeout_governor);
550 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
553 struct device *dev = container_of(kobj, struct device, kobj);
554 struct watchdog_device *wdd = dev_get_drvdata(dev);
555 umode_t mode = attr->mode;
557 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
559 else if (attr == &dev_attr_pretimeout.attr &&
560 !(wdd->info->options & WDIOF_PRETIMEOUT))
562 else if ((attr == &dev_attr_pretimeout_governor.attr ||
563 attr == &dev_attr_pretimeout_available_governors.attr) &&
564 (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
565 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
570 static struct attribute *wdt_attrs[] = {
571 &dev_attr_state.attr,
572 &dev_attr_identity.attr,
573 &dev_attr_timeout.attr,
574 &dev_attr_pretimeout.attr,
575 &dev_attr_timeleft.attr,
576 &dev_attr_bootstatus.attr,
577 &dev_attr_status.attr,
578 &dev_attr_nowayout.attr,
579 &dev_attr_pretimeout_governor.attr,
580 &dev_attr_pretimeout_available_governors.attr,
584 static const struct attribute_group wdt_group = {
586 .is_visible = wdt_is_visible,
588 __ATTRIBUTE_GROUPS(wdt);
590 #define wdt_groups NULL
594 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
595 * @wdd: the watchdog device to do the ioctl on
596 * @cmd: watchdog command
597 * @arg: argument pointer
599 * The caller must hold wd_data->lock.
602 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
605 if (!wdd->ops->ioctl)
608 return wdd->ops->ioctl(wdd, cmd, arg);
612 * watchdog_write: writes to the watchdog.
613 * @file: file from VFS
614 * @data: user address of data
615 * @len: length of data
616 * @ppos: pointer to the file offset
618 * A write to a watchdog device is defined as a keepalive ping.
619 * Writing the magic 'V' sequence allows the next close to turn
620 * off the watchdog (if 'nowayout' is not set).
623 static ssize_t watchdog_write(struct file *file, const char __user *data,
624 size_t len, loff_t *ppos)
626 struct watchdog_core_data *wd_data = file->private_data;
627 struct watchdog_device *wdd;
636 * Note: just in case someone wrote the magic character
639 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
641 /* scan to see whether or not we got the magic character */
642 for (i = 0; i != len; i++) {
643 if (get_user(c, data + i))
646 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
649 /* someone wrote to us, so we send the watchdog a keepalive ping */
652 mutex_lock(&wd_data->lock);
655 err = watchdog_ping(wdd);
656 mutex_unlock(&wd_data->lock);
665 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
666 * @file: file handle to the device
667 * @cmd: watchdog command
668 * @arg: argument pointer
670 * The watchdog API defines a common set of functions for all watchdogs
671 * according to their available features.
674 static long watchdog_ioctl(struct file *file, unsigned int cmd,
677 struct watchdog_core_data *wd_data = file->private_data;
678 void __user *argp = (void __user *)arg;
679 struct watchdog_device *wdd;
680 int __user *p = argp;
684 mutex_lock(&wd_data->lock);
692 err = watchdog_ioctl_op(wdd, cmd, arg);
693 if (err != -ENOIOCTLCMD)
697 case WDIOC_GETSUPPORT:
698 err = copy_to_user(argp, wdd->info,
699 sizeof(struct watchdog_info)) ? -EFAULT : 0;
701 case WDIOC_GETSTATUS:
702 val = watchdog_get_status(wdd);
703 err = put_user(val, p);
705 case WDIOC_GETBOOTSTATUS:
706 err = put_user(wdd->bootstatus, p);
708 case WDIOC_SETOPTIONS:
709 if (get_user(val, p)) {
713 if (val & WDIOS_DISABLECARD) {
714 err = watchdog_stop(wdd);
718 if (val & WDIOS_ENABLECARD)
719 err = watchdog_start(wdd);
721 case WDIOC_KEEPALIVE:
722 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
726 err = watchdog_ping(wdd);
728 case WDIOC_SETTIMEOUT:
729 if (get_user(val, p)) {
733 err = watchdog_set_timeout(wdd, val);
736 /* If the watchdog is active then we send a keepalive ping
737 * to make sure that the watchdog keep's running (and if
738 * possible that it takes the new timeout) */
739 err = watchdog_ping(wdd);
743 case WDIOC_GETTIMEOUT:
744 /* timeout == 0 means that we don't know the timeout */
745 if (wdd->timeout == 0) {
749 err = put_user(wdd->timeout, p);
751 case WDIOC_GETTIMELEFT:
752 err = watchdog_get_timeleft(wdd, &val);
755 err = put_user(val, p);
757 case WDIOC_SETPRETIMEOUT:
758 if (get_user(val, p)) {
762 err = watchdog_set_pretimeout(wdd, val);
764 case WDIOC_GETPRETIMEOUT:
765 err = put_user(wdd->pretimeout, p);
773 mutex_unlock(&wd_data->lock);
778 * watchdog_open: open the /dev/watchdog* devices.
779 * @inode: inode of device
780 * @file: file handle to device
782 * When the /dev/watchdog* device gets opened, we start the watchdog.
783 * Watch out: the /dev/watchdog device is single open, so we make sure
784 * it can only be opened once.
787 static int watchdog_open(struct inode *inode, struct file *file)
789 struct watchdog_core_data *wd_data;
790 struct watchdog_device *wdd;
794 /* Get the corresponding watchdog device */
795 if (imajor(inode) == MISC_MAJOR)
796 wd_data = old_wd_data;
798 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
801 /* the watchdog is single open! */
802 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
808 * If the /dev/watchdog device is open, we don't want the module
811 hw_running = watchdog_hw_running(wdd);
812 if (!hw_running && !try_module_get(wdd->ops->owner)) {
817 err = watchdog_start(wdd);
821 file->private_data = wd_data;
824 get_device(&wd_data->dev);
826 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
827 return nonseekable_open(inode, file);
830 module_put(wd_data->wdd->ops->owner);
832 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
836 static void watchdog_core_data_release(struct device *dev)
838 struct watchdog_core_data *wd_data;
840 wd_data = container_of(dev, struct watchdog_core_data, dev);
846 * watchdog_release: release the watchdog device.
847 * @inode: inode of device
848 * @file: file handle to device
850 * This is the code for when /dev/watchdog gets closed. We will only
851 * stop the watchdog when we have received the magic char (and nowayout
852 * was not set), else the watchdog will keep running.
855 static int watchdog_release(struct inode *inode, struct file *file)
857 struct watchdog_core_data *wd_data = file->private_data;
858 struct watchdog_device *wdd;
862 mutex_lock(&wd_data->lock);
869 * We only stop the watchdog if we received the magic character
870 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
871 * watchdog_stop will fail.
873 if (!test_bit(WDOG_ACTIVE, &wdd->status))
875 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
876 !(wdd->info->options & WDIOF_MAGICCLOSE))
877 err = watchdog_stop(wdd);
879 /* If the watchdog was not stopped, send a keepalive ping */
881 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
885 watchdog_update_worker(wdd);
887 /* make sure that /dev/watchdog can be re-opened */
888 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
891 running = wdd && watchdog_hw_running(wdd);
892 mutex_unlock(&wd_data->lock);
894 * Allow the owner module to be unloaded again unless the watchdog
895 * is still running. If the watchdog is still running, it can not
896 * be stopped, and its driver must not be unloaded.
899 module_put(wd_data->cdev.owner);
900 put_device(&wd_data->dev);
905 static const struct file_operations watchdog_fops = {
906 .owner = THIS_MODULE,
907 .write = watchdog_write,
908 .unlocked_ioctl = watchdog_ioctl,
909 .open = watchdog_open,
910 .release = watchdog_release,
913 static struct miscdevice watchdog_miscdev = {
914 .minor = WATCHDOG_MINOR,
916 .fops = &watchdog_fops,
919 static struct class watchdog_class = {
921 .owner = THIS_MODULE,
922 .dev_groups = wdt_groups,
926 * watchdog_cdev_register: register watchdog character device
927 * @wdd: watchdog device
929 * Register a watchdog character device including handling the legacy
930 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
931 * thus we set it up like that.
934 static int watchdog_cdev_register(struct watchdog_device *wdd)
936 struct watchdog_core_data *wd_data;
939 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
942 mutex_init(&wd_data->lock);
945 wdd->wd_data = wd_data;
947 if (IS_ERR_OR_NULL(watchdog_kworker)) {
952 device_initialize(&wd_data->dev);
953 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
954 wd_data->dev.class = &watchdog_class;
955 wd_data->dev.parent = wdd->parent;
956 wd_data->dev.groups = wdd->groups;
957 wd_data->dev.release = watchdog_core_data_release;
958 dev_set_drvdata(&wd_data->dev, wdd);
959 dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
961 kthread_init_work(&wd_data->work, watchdog_ping_work);
962 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
963 wd_data->timer.function = watchdog_timer_expired;
966 old_wd_data = wd_data;
967 watchdog_miscdev.parent = wdd->parent;
968 err = misc_register(&watchdog_miscdev);
970 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
971 wdd->info->identity, WATCHDOG_MINOR, err);
973 pr_err("%s: a legacy watchdog module is probably present.\n",
974 wdd->info->identity);
976 put_device(&wd_data->dev);
981 /* Fill in the data structures */
982 cdev_init(&wd_data->cdev, &watchdog_fops);
985 err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
987 pr_err("watchdog%d unable to add device %d:%d\n",
988 wdd->id, MAJOR(watchdog_devt), wdd->id);
990 misc_deregister(&watchdog_miscdev);
992 put_device(&wd_data->dev);
997 wd_data->cdev.owner = wdd->ops->owner;
999 /* Record time of most recent heartbeat as 'just before now'. */
1000 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
1003 * If the watchdog is running, prevent its driver from being unloaded,
1004 * and schedule an immediate ping.
1006 if (watchdog_hw_running(wdd)) {
1007 __module_get(wdd->ops->owner);
1008 get_device(&wd_data->dev);
1009 if (handle_boot_enabled)
1010 hrtimer_start(&wd_data->timer, 0, HRTIMER_MODE_REL);
1012 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
1020 * watchdog_cdev_unregister: unregister watchdog character device
1021 * @watchdog: watchdog device
1023 * Unregister watchdog character device and if needed the legacy
1024 * /dev/watchdog device.
1027 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
1029 struct watchdog_core_data *wd_data = wdd->wd_data;
1031 cdev_device_del(&wd_data->cdev, &wd_data->dev);
1033 misc_deregister(&watchdog_miscdev);
1037 if (watchdog_active(wdd) &&
1038 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
1042 mutex_lock(&wd_data->lock);
1043 wd_data->wdd = NULL;
1044 wdd->wd_data = NULL;
1045 mutex_unlock(&wd_data->lock);
1047 hrtimer_cancel(&wd_data->timer);
1048 kthread_cancel_work_sync(&wd_data->work);
1050 put_device(&wd_data->dev);
1054 * watchdog_dev_register: register a watchdog device
1055 * @wdd: watchdog device
1057 * Register a watchdog device including handling the legacy
1058 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1059 * thus we set it up like that.
1062 int watchdog_dev_register(struct watchdog_device *wdd)
1066 ret = watchdog_cdev_register(wdd);
1070 ret = watchdog_register_pretimeout(wdd);
1072 watchdog_cdev_unregister(wdd);
1078 * watchdog_dev_unregister: unregister a watchdog device
1079 * @watchdog: watchdog device
1081 * Unregister watchdog device and if needed the legacy
1082 * /dev/watchdog device.
1085 void watchdog_dev_unregister(struct watchdog_device *wdd)
1087 watchdog_unregister_pretimeout(wdd);
1088 watchdog_cdev_unregister(wdd);
1092 * watchdog_dev_init: init dev part of watchdog core
1094 * Allocate a range of chardev nodes to use for watchdog devices
1097 int __init watchdog_dev_init(void)
1100 struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,};
1102 watchdog_kworker = kthread_create_worker(0, "watchdogd");
1103 if (IS_ERR(watchdog_kworker)) {
1104 pr_err("Failed to create watchdog kworker\n");
1105 return PTR_ERR(watchdog_kworker);
1107 sched_setscheduler(watchdog_kworker->task, SCHED_FIFO, ¶m);
1109 err = class_register(&watchdog_class);
1111 pr_err("couldn't register class\n");
1115 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1117 pr_err("watchdog: unable to allocate char dev region\n");
1124 class_unregister(&watchdog_class);
1126 kthread_destroy_worker(watchdog_kworker);
1131 * watchdog_dev_exit: exit dev part of watchdog core
1133 * Release the range of chardev nodes used for watchdog devices
1136 void __exit watchdog_dev_exit(void)
1138 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1139 class_unregister(&watchdog_class);
1140 kthread_destroy_worker(watchdog_kworker);
1143 module_param(handle_boot_enabled, bool, 0444);
1144 MODULE_PARM_DESC(handle_boot_enabled,
1145 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1146 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");