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/jiffies.h> /* For timeout functions */
40 #include <linux/kernel.h> /* For printk/panic/... */
41 #include <linux/kref.h> /* For data references */
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/workqueue.h> /* For workqueue */
49 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */
51 #include "watchdog_core.h"
54 * struct watchdog_core_data - watchdog core internal data
55 * @kref: Reference count.
56 * @cdev: The watchdog's Character device.
57 * @wdd: Pointer to watchdog device.
58 * @lock: Lock for watchdog core.
59 * @status: Watchdog core internal status bits.
61 struct watchdog_core_data {
64 struct watchdog_device *wdd;
66 unsigned long last_keepalive;
67 unsigned long last_hw_keepalive;
68 struct delayed_work work;
69 unsigned long status; /* Internal status bits */
70 #define _WDOG_DEV_OPEN 0 /* Opened ? */
71 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
74 /* the dev_t structure to store the dynamically allocated watchdog devices */
75 static dev_t watchdog_devt;
76 /* Reference to watchdog device behind /dev/watchdog */
77 static struct watchdog_core_data *old_wd_data;
79 static struct workqueue_struct *watchdog_wq;
81 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
83 /* All variables in milli-seconds */
84 unsigned int hm = wdd->max_hw_heartbeat_ms;
85 unsigned int t = wdd->timeout * 1000;
88 * A worker to generate heartbeat requests is needed if all of the
89 * following conditions are true.
90 * - Userspace activated the watchdog.
91 * - The driver provided a value for the maximum hardware timeout, and
92 * thus is aware that the framework supports generating heartbeat
94 * - Userspace requests a longer timeout than the hardware can handle.
96 * Alternatively, if userspace has not opened the watchdog
97 * device, we take care of feeding the watchdog if it is
100 return (hm && watchdog_active(wdd) && t > hm) ||
101 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
104 static long watchdog_next_keepalive(struct watchdog_device *wdd)
106 struct watchdog_core_data *wd_data = wdd->wd_data;
107 unsigned int timeout_ms = wdd->timeout * 1000;
108 unsigned long keepalive_interval;
109 unsigned long last_heartbeat;
110 unsigned long virt_timeout;
111 unsigned int hw_heartbeat_ms;
113 virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
114 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
115 keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);
117 if (!watchdog_active(wdd))
118 return keepalive_interval;
121 * To ensure that the watchdog times out wdd->timeout seconds
122 * after the most recent ping from userspace, the last
123 * worker ping has to come in hw_heartbeat_ms before this timeout.
125 last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
126 return min_t(long, last_heartbeat - jiffies, keepalive_interval);
129 static inline void watchdog_update_worker(struct watchdog_device *wdd)
131 struct watchdog_core_data *wd_data = wdd->wd_data;
133 if (watchdog_need_worker(wdd)) {
134 long t = watchdog_next_keepalive(wdd);
137 mod_delayed_work(watchdog_wq, &wd_data->work, t);
139 cancel_delayed_work(&wd_data->work);
143 static int __watchdog_ping(struct watchdog_device *wdd)
145 struct watchdog_core_data *wd_data = wdd->wd_data;
146 unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
147 msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
150 if (time_is_after_jiffies(earliest_keepalive)) {
151 mod_delayed_work(watchdog_wq, &wd_data->work,
152 earliest_keepalive - jiffies);
156 wd_data->last_hw_keepalive = jiffies;
159 err = wdd->ops->ping(wdd); /* ping the watchdog */
161 err = wdd->ops->start(wdd); /* restart watchdog */
163 watchdog_update_worker(wdd);
169 * watchdog_ping: ping the watchdog.
170 * @wdd: the watchdog device to ping
172 * The caller must hold wd_data->lock.
174 * If the watchdog has no own ping operation then it needs to be
175 * restarted via the start operation. This wrapper function does
177 * We only ping when the watchdog device is running.
180 static int watchdog_ping(struct watchdog_device *wdd)
182 struct watchdog_core_data *wd_data = wdd->wd_data;
184 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
187 wd_data->last_keepalive = jiffies;
188 return __watchdog_ping(wdd);
191 static void watchdog_ping_work(struct work_struct *work)
193 struct watchdog_core_data *wd_data;
194 struct watchdog_device *wdd;
196 wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
199 mutex_lock(&wd_data->lock);
201 if (wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd)))
202 __watchdog_ping(wdd);
203 mutex_unlock(&wd_data->lock);
207 * watchdog_start: wrapper to start the watchdog.
208 * @wdd: the watchdog device to start
210 * The caller must hold wd_data->lock.
212 * Start the watchdog if it is not active and mark it active.
213 * This function returns zero on success or a negative errno code for
217 static int watchdog_start(struct watchdog_device *wdd)
219 struct watchdog_core_data *wd_data = wdd->wd_data;
220 unsigned long started_at;
223 if (watchdog_active(wdd))
226 started_at = jiffies;
227 if (watchdog_hw_running(wdd) && wdd->ops->ping)
228 err = wdd->ops->ping(wdd);
230 err = wdd->ops->start(wdd);
232 set_bit(WDOG_ACTIVE, &wdd->status);
233 wd_data->last_keepalive = started_at;
234 watchdog_update_worker(wdd);
241 * watchdog_stop: wrapper to stop the watchdog.
242 * @wdd: the watchdog device to stop
244 * The caller must hold wd_data->lock.
246 * Stop the watchdog if it is still active and unmark it active.
247 * This function returns zero on success or a negative errno code for
249 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
252 static int watchdog_stop(struct watchdog_device *wdd)
256 if (!watchdog_active(wdd))
259 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
260 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
266 err = wdd->ops->stop(wdd);
268 set_bit(WDOG_HW_RUNNING, &wdd->status);
271 clear_bit(WDOG_ACTIVE, &wdd->status);
272 watchdog_update_worker(wdd);
279 * watchdog_get_status: wrapper to get the watchdog status
280 * @wdd: the watchdog device to get the status from
282 * The caller must hold wd_data->lock.
284 * Get the watchdog's status flags.
287 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
289 if (!wdd->ops->status)
292 return wdd->ops->status(wdd);
296 * watchdog_set_timeout: set the watchdog timer timeout
297 * @wdd: the watchdog device to set the timeout for
298 * @timeout: timeout to set in seconds
300 * The caller must hold wd_data->lock.
303 static int watchdog_set_timeout(struct watchdog_device *wdd,
304 unsigned int timeout)
308 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
311 if (watchdog_timeout_invalid(wdd, timeout))
314 if (wdd->ops->set_timeout)
315 err = wdd->ops->set_timeout(wdd, timeout);
317 wdd->timeout = timeout;
319 watchdog_update_worker(wdd);
325 * watchdog_get_timeleft: wrapper to get the time left before a reboot
326 * @wdd: the watchdog device to get the remaining time from
327 * @timeleft: the time that's left
329 * The caller must hold wd_data->lock.
331 * Get the time before a watchdog will reboot (if not pinged).
334 static int watchdog_get_timeleft(struct watchdog_device *wdd,
335 unsigned int *timeleft)
339 if (!wdd->ops->get_timeleft)
342 *timeleft = wdd->ops->get_timeleft(wdd);
347 #ifdef CONFIG_WATCHDOG_SYSFS
348 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
351 struct watchdog_device *wdd = dev_get_drvdata(dev);
353 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
355 static DEVICE_ATTR_RO(nowayout);
357 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
360 struct watchdog_device *wdd = dev_get_drvdata(dev);
361 struct watchdog_core_data *wd_data = wdd->wd_data;
364 mutex_lock(&wd_data->lock);
365 status = watchdog_get_status(wdd);
366 mutex_unlock(&wd_data->lock);
368 return sprintf(buf, "%u\n", status);
370 static DEVICE_ATTR_RO(status);
372 static ssize_t bootstatus_show(struct device *dev,
373 struct device_attribute *attr, char *buf)
375 struct watchdog_device *wdd = dev_get_drvdata(dev);
377 return sprintf(buf, "%u\n", wdd->bootstatus);
379 static DEVICE_ATTR_RO(bootstatus);
381 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
384 struct watchdog_device *wdd = dev_get_drvdata(dev);
385 struct watchdog_core_data *wd_data = wdd->wd_data;
389 mutex_lock(&wd_data->lock);
390 status = watchdog_get_timeleft(wdd, &val);
391 mutex_unlock(&wd_data->lock);
393 status = sprintf(buf, "%u\n", val);
397 static DEVICE_ATTR_RO(timeleft);
399 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
402 struct watchdog_device *wdd = dev_get_drvdata(dev);
404 return sprintf(buf, "%u\n", wdd->timeout);
406 static DEVICE_ATTR_RO(timeout);
408 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
411 struct watchdog_device *wdd = dev_get_drvdata(dev);
413 return sprintf(buf, "%s\n", wdd->info->identity);
415 static DEVICE_ATTR_RO(identity);
417 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
420 struct watchdog_device *wdd = dev_get_drvdata(dev);
422 if (watchdog_active(wdd))
423 return sprintf(buf, "active\n");
425 return sprintf(buf, "inactive\n");
427 static DEVICE_ATTR_RO(state);
429 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
432 struct device *dev = container_of(kobj, struct device, kobj);
433 struct watchdog_device *wdd = dev_get_drvdata(dev);
434 umode_t mode = attr->mode;
436 if (attr == &dev_attr_status.attr && !wdd->ops->status)
438 else if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
443 static struct attribute *wdt_attrs[] = {
444 &dev_attr_state.attr,
445 &dev_attr_identity.attr,
446 &dev_attr_timeout.attr,
447 &dev_attr_timeleft.attr,
448 &dev_attr_bootstatus.attr,
449 &dev_attr_status.attr,
450 &dev_attr_nowayout.attr,
454 static const struct attribute_group wdt_group = {
456 .is_visible = wdt_is_visible,
458 __ATTRIBUTE_GROUPS(wdt);
460 #define wdt_groups NULL
464 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
465 * @wdd: the watchdog device to do the ioctl on
466 * @cmd: watchdog command
467 * @arg: argument pointer
469 * The caller must hold wd_data->lock.
472 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
475 if (!wdd->ops->ioctl)
478 return wdd->ops->ioctl(wdd, cmd, arg);
482 * watchdog_write: writes to the watchdog.
483 * @file: file from VFS
484 * @data: user address of data
485 * @len: length of data
486 * @ppos: pointer to the file offset
488 * A write to a watchdog device is defined as a keepalive ping.
489 * Writing the magic 'V' sequence allows the next close to turn
490 * off the watchdog (if 'nowayout' is not set).
493 static ssize_t watchdog_write(struct file *file, const char __user *data,
494 size_t len, loff_t *ppos)
496 struct watchdog_core_data *wd_data = file->private_data;
497 struct watchdog_device *wdd;
506 * Note: just in case someone wrote the magic character
509 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
511 /* scan to see whether or not we got the magic character */
512 for (i = 0; i != len; i++) {
513 if (get_user(c, data + i))
516 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
519 /* someone wrote to us, so we send the watchdog a keepalive ping */
522 mutex_lock(&wd_data->lock);
525 err = watchdog_ping(wdd);
526 mutex_unlock(&wd_data->lock);
535 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
536 * @file: file handle to the device
537 * @cmd: watchdog command
538 * @arg: argument pointer
540 * The watchdog API defines a common set of functions for all watchdogs
541 * according to their available features.
544 static long watchdog_ioctl(struct file *file, unsigned int cmd,
547 struct watchdog_core_data *wd_data = file->private_data;
548 void __user *argp = (void __user *)arg;
549 struct watchdog_device *wdd;
550 int __user *p = argp;
554 mutex_lock(&wd_data->lock);
562 err = watchdog_ioctl_op(wdd, cmd, arg);
563 if (err != -ENOIOCTLCMD)
567 case WDIOC_GETSUPPORT:
568 err = copy_to_user(argp, wdd->info,
569 sizeof(struct watchdog_info)) ? -EFAULT : 0;
571 case WDIOC_GETSTATUS:
572 val = watchdog_get_status(wdd);
573 err = put_user(val, p);
575 case WDIOC_GETBOOTSTATUS:
576 err = put_user(wdd->bootstatus, p);
578 case WDIOC_SETOPTIONS:
579 if (get_user(val, p)) {
583 if (val & WDIOS_DISABLECARD) {
584 err = watchdog_stop(wdd);
588 if (val & WDIOS_ENABLECARD)
589 err = watchdog_start(wdd);
591 case WDIOC_KEEPALIVE:
592 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
596 err = watchdog_ping(wdd);
598 case WDIOC_SETTIMEOUT:
599 if (get_user(val, p)) {
603 err = watchdog_set_timeout(wdd, val);
606 /* If the watchdog is active then we send a keepalive ping
607 * to make sure that the watchdog keep's running (and if
608 * possible that it takes the new timeout) */
609 err = watchdog_ping(wdd);
613 case WDIOC_GETTIMEOUT:
614 /* timeout == 0 means that we don't know the timeout */
615 if (wdd->timeout == 0) {
619 err = put_user(wdd->timeout, p);
621 case WDIOC_GETTIMELEFT:
622 err = watchdog_get_timeleft(wdd, &val);
625 err = put_user(val, p);
633 mutex_unlock(&wd_data->lock);
638 * watchdog_open: open the /dev/watchdog* devices.
639 * @inode: inode of device
640 * @file: file handle to device
642 * When the /dev/watchdog* device gets opened, we start the watchdog.
643 * Watch out: the /dev/watchdog device is single open, so we make sure
644 * it can only be opened once.
647 static int watchdog_open(struct inode *inode, struct file *file)
649 struct watchdog_core_data *wd_data;
650 struct watchdog_device *wdd;
653 /* Get the corresponding watchdog device */
654 if (imajor(inode) == MISC_MAJOR)
655 wd_data = old_wd_data;
657 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
660 /* the watchdog is single open! */
661 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
667 * If the /dev/watchdog device is open, we don't want the module
670 if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
675 err = watchdog_start(wdd);
679 file->private_data = wd_data;
681 if (!watchdog_hw_running(wdd))
682 kref_get(&wd_data->kref);
684 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
685 return nonseekable_open(inode, file);
688 module_put(wd_data->wdd->ops->owner);
690 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
694 static void watchdog_core_data_release(struct kref *kref)
696 struct watchdog_core_data *wd_data;
698 wd_data = container_of(kref, struct watchdog_core_data, kref);
704 * watchdog_release: release the watchdog device.
705 * @inode: inode of device
706 * @file: file handle to device
708 * This is the code for when /dev/watchdog gets closed. We will only
709 * stop the watchdog when we have received the magic char (and nowayout
710 * was not set), else the watchdog will keep running.
713 static int watchdog_release(struct inode *inode, struct file *file)
715 struct watchdog_core_data *wd_data = file->private_data;
716 struct watchdog_device *wdd;
720 mutex_lock(&wd_data->lock);
727 * We only stop the watchdog if we received the magic character
728 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
729 * watchdog_stop will fail.
731 if (!test_bit(WDOG_ACTIVE, &wdd->status))
733 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
734 !(wdd->info->options & WDIOF_MAGICCLOSE))
735 err = watchdog_stop(wdd);
737 /* If the watchdog was not stopped, send a keepalive ping */
739 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
743 watchdog_update_worker(wdd);
745 /* make sure that /dev/watchdog can be re-opened */
746 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
749 running = wdd && watchdog_hw_running(wdd);
750 mutex_unlock(&wd_data->lock);
752 * Allow the owner module to be unloaded again unless the watchdog
753 * is still running. If the watchdog is still running, it can not
754 * be stopped, and its driver must not be unloaded.
757 module_put(wd_data->cdev.owner);
758 kref_put(&wd_data->kref, watchdog_core_data_release);
763 static const struct file_operations watchdog_fops = {
764 .owner = THIS_MODULE,
765 .write = watchdog_write,
766 .unlocked_ioctl = watchdog_ioctl,
767 .open = watchdog_open,
768 .release = watchdog_release,
771 static struct miscdevice watchdog_miscdev = {
772 .minor = WATCHDOG_MINOR,
774 .fops = &watchdog_fops,
778 * watchdog_cdev_register: register watchdog character device
779 * @wdd: watchdog device
780 * @devno: character device number
782 * Register a watchdog character device including handling the legacy
783 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
784 * thus we set it up like that.
787 static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
789 struct watchdog_core_data *wd_data;
792 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
795 kref_init(&wd_data->kref);
796 mutex_init(&wd_data->lock);
799 wdd->wd_data = wd_data;
804 INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
807 old_wd_data = wd_data;
808 watchdog_miscdev.parent = wdd->parent;
809 err = misc_register(&watchdog_miscdev);
811 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
812 wdd->info->identity, WATCHDOG_MINOR, err);
814 pr_err("%s: a legacy watchdog module is probably present.\n",
815 wdd->info->identity);
822 /* Fill in the data structures */
823 cdev_init(&wd_data->cdev, &watchdog_fops);
824 wd_data->cdev.owner = wdd->ops->owner;
827 err = cdev_add(&wd_data->cdev, devno, 1);
829 pr_err("watchdog%d unable to add device %d:%d\n",
830 wdd->id, MAJOR(watchdog_devt), wdd->id);
832 misc_deregister(&watchdog_miscdev);
834 kref_put(&wd_data->kref, watchdog_core_data_release);
839 /* Record time of most recent heartbeat as 'just before now'. */
840 wd_data->last_hw_keepalive = jiffies - 1;
843 * If the watchdog is running, prevent its driver from being unloaded,
844 * and schedule an immediate ping.
846 if (watchdog_hw_running(wdd)) {
847 __module_get(wdd->ops->owner);
848 kref_get(&wd_data->kref);
849 queue_delayed_work(watchdog_wq, &wd_data->work, 0);
856 * watchdog_cdev_unregister: unregister watchdog character device
857 * @watchdog: watchdog device
859 * Unregister watchdog character device and if needed the legacy
860 * /dev/watchdog device.
863 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
865 struct watchdog_core_data *wd_data = wdd->wd_data;
867 cdev_del(&wd_data->cdev);
869 misc_deregister(&watchdog_miscdev);
873 mutex_lock(&wd_data->lock);
876 mutex_unlock(&wd_data->lock);
878 cancel_delayed_work_sync(&wd_data->work);
880 kref_put(&wd_data->kref, watchdog_core_data_release);
883 static struct class watchdog_class = {
885 .owner = THIS_MODULE,
886 .dev_groups = wdt_groups,
890 * watchdog_dev_register: register a watchdog device
891 * @wdd: watchdog device
893 * Register a watchdog device including handling the legacy
894 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
895 * thus we set it up like that.
898 int watchdog_dev_register(struct watchdog_device *wdd)
904 devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
906 ret = watchdog_cdev_register(wdd, devno);
910 dev = device_create_with_groups(&watchdog_class, wdd->parent,
911 devno, wdd, wdd->groups,
912 "watchdog%d", wdd->id);
914 watchdog_cdev_unregister(wdd);
922 * watchdog_dev_unregister: unregister a watchdog device
923 * @watchdog: watchdog device
925 * Unregister watchdog device and if needed the legacy
926 * /dev/watchdog device.
929 void watchdog_dev_unregister(struct watchdog_device *wdd)
931 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
932 watchdog_cdev_unregister(wdd);
936 * watchdog_dev_init: init dev part of watchdog core
938 * Allocate a range of chardev nodes to use for watchdog devices
941 int __init watchdog_dev_init(void)
945 watchdog_wq = alloc_workqueue("watchdogd",
946 WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
948 pr_err("Failed to create watchdog workqueue\n");
952 err = class_register(&watchdog_class);
954 pr_err("couldn't register class\n");
958 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
960 pr_err("watchdog: unable to allocate char dev region\n");
961 class_unregister(&watchdog_class);
969 * watchdog_dev_exit: exit dev part of watchdog core
971 * Release the range of chardev nodes used for watchdog devices
974 void __exit watchdog_dev_exit(void)
976 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
977 class_unregister(&watchdog_class);
978 destroy_workqueue(watchdog_wq);