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 ? */
72 #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
75 /* the dev_t structure to store the dynamically allocated watchdog devices */
76 static dev_t watchdog_devt;
77 /* Reference to watchdog device behind /dev/watchdog */
78 static struct watchdog_core_data *old_wd_data;
80 static struct workqueue_struct *watchdog_wq;
82 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
84 /* All variables in milli-seconds */
85 unsigned int hm = wdd->max_hw_heartbeat_ms;
86 unsigned int t = wdd->timeout * 1000;
89 * A worker to generate heartbeat requests is needed if all of the
90 * following conditions are true.
91 * - Userspace activated the watchdog.
92 * - The driver provided a value for the maximum hardware timeout, and
93 * thus is aware that the framework supports generating heartbeat
95 * - Userspace requests a longer timeout than the hardware can handle.
97 * Alternatively, if userspace has not opened the watchdog
98 * device, we take care of feeding the watchdog if it is
101 return (hm && watchdog_active(wdd) && t > hm) ||
102 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
105 static long watchdog_next_keepalive(struct watchdog_device *wdd)
107 struct watchdog_core_data *wd_data = wdd->wd_data;
108 unsigned int timeout_ms = wdd->timeout * 1000;
109 unsigned long keepalive_interval;
110 unsigned long last_heartbeat;
111 unsigned long virt_timeout;
112 unsigned int hw_heartbeat_ms;
114 virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
115 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
116 keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);
118 if (!watchdog_active(wdd))
119 return keepalive_interval;
122 * To ensure that the watchdog times out wdd->timeout seconds
123 * after the most recent ping from userspace, the last
124 * worker ping has to come in hw_heartbeat_ms before this timeout.
126 last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
127 return min_t(long, last_heartbeat - jiffies, keepalive_interval);
130 static inline void watchdog_update_worker(struct watchdog_device *wdd)
132 struct watchdog_core_data *wd_data = wdd->wd_data;
134 if (watchdog_need_worker(wdd)) {
135 long t = watchdog_next_keepalive(wdd);
138 mod_delayed_work(watchdog_wq, &wd_data->work, t);
140 cancel_delayed_work(&wd_data->work);
144 static int __watchdog_ping(struct watchdog_device *wdd)
146 struct watchdog_core_data *wd_data = wdd->wd_data;
147 unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
148 msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
151 if (time_is_after_jiffies(earliest_keepalive)) {
152 mod_delayed_work(watchdog_wq, &wd_data->work,
153 earliest_keepalive - jiffies);
157 wd_data->last_hw_keepalive = jiffies;
160 err = wdd->ops->ping(wdd); /* ping the watchdog */
162 err = wdd->ops->start(wdd); /* restart watchdog */
164 watchdog_update_worker(wdd);
170 * watchdog_ping: ping the watchdog.
171 * @wdd: the watchdog device to ping
173 * The caller must hold wd_data->lock.
175 * If the watchdog has no own ping operation then it needs to be
176 * restarted via the start operation. This wrapper function does
178 * We only ping when the watchdog device is running.
181 static int watchdog_ping(struct watchdog_device *wdd)
183 struct watchdog_core_data *wd_data = wdd->wd_data;
185 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
188 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
190 wd_data->last_keepalive = jiffies;
191 return __watchdog_ping(wdd);
194 static void watchdog_ping_work(struct work_struct *work)
196 struct watchdog_core_data *wd_data;
197 struct watchdog_device *wdd;
199 wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
202 mutex_lock(&wd_data->lock);
204 if (wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd)))
205 __watchdog_ping(wdd);
206 mutex_unlock(&wd_data->lock);
210 * watchdog_start: wrapper to start the watchdog.
211 * @wdd: the watchdog device to start
213 * The caller must hold wd_data->lock.
215 * Start the watchdog if it is not active and mark it active.
216 * This function returns zero on success or a negative errno code for
220 static int watchdog_start(struct watchdog_device *wdd)
222 struct watchdog_core_data *wd_data = wdd->wd_data;
223 unsigned long started_at;
226 if (watchdog_active(wdd))
229 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
231 started_at = jiffies;
232 if (watchdog_hw_running(wdd) && wdd->ops->ping)
233 err = wdd->ops->ping(wdd);
235 err = wdd->ops->start(wdd);
237 set_bit(WDOG_ACTIVE, &wdd->status);
238 wd_data->last_keepalive = started_at;
239 watchdog_update_worker(wdd);
246 * watchdog_stop: wrapper to stop the watchdog.
247 * @wdd: the watchdog device to stop
249 * The caller must hold wd_data->lock.
251 * Stop the watchdog if it is still active and unmark it active.
252 * This function returns zero on success or a negative errno code for
254 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
257 static int watchdog_stop(struct watchdog_device *wdd)
261 if (!watchdog_active(wdd))
264 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
265 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
270 if (wdd->ops->stop) {
271 clear_bit(WDOG_HW_RUNNING, &wdd->status);
272 err = wdd->ops->stop(wdd);
274 set_bit(WDOG_HW_RUNNING, &wdd->status);
278 clear_bit(WDOG_ACTIVE, &wdd->status);
279 watchdog_update_worker(wdd);
286 * watchdog_get_status: wrapper to get the watchdog status
287 * @wdd: the watchdog device to get the status from
289 * The caller must hold wd_data->lock.
291 * Get the watchdog's status flags.
294 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
296 struct watchdog_core_data *wd_data = wdd->wd_data;
299 if (wdd->ops->status)
300 status = wdd->ops->status(wdd);
302 status = wdd->bootstatus & (WDIOF_CARDRESET |
310 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
311 status |= WDIOF_MAGICCLOSE;
313 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
314 status |= WDIOF_KEEPALIVEPING;
320 * watchdog_set_timeout: set the watchdog timer timeout
321 * @wdd: the watchdog device to set the timeout for
322 * @timeout: timeout to set in seconds
324 * The caller must hold wd_data->lock.
327 static int watchdog_set_timeout(struct watchdog_device *wdd,
328 unsigned int timeout)
332 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
335 if (watchdog_timeout_invalid(wdd, timeout))
338 if (wdd->ops->set_timeout) {
339 err = wdd->ops->set_timeout(wdd, timeout);
341 wdd->timeout = timeout;
342 /* Disable pretimeout if it doesn't fit the new timeout */
343 if (wdd->pretimeout >= wdd->timeout)
347 watchdog_update_worker(wdd);
353 * watchdog_set_pretimeout: set the watchdog timer pretimeout
354 * @wdd: the watchdog device to set the timeout for
355 * @timeout: pretimeout to set in seconds
358 static int watchdog_set_pretimeout(struct watchdog_device *wdd,
359 unsigned int timeout)
363 if (!(wdd->info->options & WDIOF_PRETIMEOUT))
366 if (watchdog_pretimeout_invalid(wdd, timeout))
369 if (wdd->ops->set_pretimeout)
370 err = wdd->ops->set_pretimeout(wdd, timeout);
372 wdd->pretimeout = timeout;
378 * watchdog_get_timeleft: wrapper to get the time left before a reboot
379 * @wdd: the watchdog device to get the remaining time from
380 * @timeleft: the time that's left
382 * The caller must hold wd_data->lock.
384 * Get the time before a watchdog will reboot (if not pinged).
387 static int watchdog_get_timeleft(struct watchdog_device *wdd,
388 unsigned int *timeleft)
392 if (!wdd->ops->get_timeleft)
395 *timeleft = wdd->ops->get_timeleft(wdd);
400 #ifdef CONFIG_WATCHDOG_SYSFS
401 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
404 struct watchdog_device *wdd = dev_get_drvdata(dev);
406 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
408 static DEVICE_ATTR_RO(nowayout);
410 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
413 struct watchdog_device *wdd = dev_get_drvdata(dev);
414 struct watchdog_core_data *wd_data = wdd->wd_data;
417 mutex_lock(&wd_data->lock);
418 status = watchdog_get_status(wdd);
419 mutex_unlock(&wd_data->lock);
421 return sprintf(buf, "0x%x\n", status);
423 static DEVICE_ATTR_RO(status);
425 static ssize_t bootstatus_show(struct device *dev,
426 struct device_attribute *attr, char *buf)
428 struct watchdog_device *wdd = dev_get_drvdata(dev);
430 return sprintf(buf, "%u\n", wdd->bootstatus);
432 static DEVICE_ATTR_RO(bootstatus);
434 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
437 struct watchdog_device *wdd = dev_get_drvdata(dev);
438 struct watchdog_core_data *wd_data = wdd->wd_data;
442 mutex_lock(&wd_data->lock);
443 status = watchdog_get_timeleft(wdd, &val);
444 mutex_unlock(&wd_data->lock);
446 status = sprintf(buf, "%u\n", val);
450 static DEVICE_ATTR_RO(timeleft);
452 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
455 struct watchdog_device *wdd = dev_get_drvdata(dev);
457 return sprintf(buf, "%u\n", wdd->timeout);
459 static DEVICE_ATTR_RO(timeout);
461 static ssize_t pretimeout_show(struct device *dev,
462 struct device_attribute *attr, char *buf)
464 struct watchdog_device *wdd = dev_get_drvdata(dev);
466 return sprintf(buf, "%u\n", wdd->pretimeout);
468 static DEVICE_ATTR_RO(pretimeout);
470 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
473 struct watchdog_device *wdd = dev_get_drvdata(dev);
475 return sprintf(buf, "%s\n", wdd->info->identity);
477 static DEVICE_ATTR_RO(identity);
479 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
482 struct watchdog_device *wdd = dev_get_drvdata(dev);
484 if (watchdog_active(wdd))
485 return sprintf(buf, "active\n");
487 return sprintf(buf, "inactive\n");
489 static DEVICE_ATTR_RO(state);
491 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
494 struct device *dev = container_of(kobj, struct device, kobj);
495 struct watchdog_device *wdd = dev_get_drvdata(dev);
496 umode_t mode = attr->mode;
498 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
500 else if (attr == &dev_attr_pretimeout.attr &&
501 !(wdd->info->options & WDIOF_PRETIMEOUT))
506 static struct attribute *wdt_attrs[] = {
507 &dev_attr_state.attr,
508 &dev_attr_identity.attr,
509 &dev_attr_timeout.attr,
510 &dev_attr_pretimeout.attr,
511 &dev_attr_timeleft.attr,
512 &dev_attr_bootstatus.attr,
513 &dev_attr_status.attr,
514 &dev_attr_nowayout.attr,
518 static const struct attribute_group wdt_group = {
520 .is_visible = wdt_is_visible,
522 __ATTRIBUTE_GROUPS(wdt);
524 #define wdt_groups NULL
528 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
529 * @wdd: the watchdog device to do the ioctl on
530 * @cmd: watchdog command
531 * @arg: argument pointer
533 * The caller must hold wd_data->lock.
536 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
539 if (!wdd->ops->ioctl)
542 return wdd->ops->ioctl(wdd, cmd, arg);
546 * watchdog_write: writes to the watchdog.
547 * @file: file from VFS
548 * @data: user address of data
549 * @len: length of data
550 * @ppos: pointer to the file offset
552 * A write to a watchdog device is defined as a keepalive ping.
553 * Writing the magic 'V' sequence allows the next close to turn
554 * off the watchdog (if 'nowayout' is not set).
557 static ssize_t watchdog_write(struct file *file, const char __user *data,
558 size_t len, loff_t *ppos)
560 struct watchdog_core_data *wd_data = file->private_data;
561 struct watchdog_device *wdd;
570 * Note: just in case someone wrote the magic character
573 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
575 /* scan to see whether or not we got the magic character */
576 for (i = 0; i != len; i++) {
577 if (get_user(c, data + i))
580 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
583 /* someone wrote to us, so we send the watchdog a keepalive ping */
586 mutex_lock(&wd_data->lock);
589 err = watchdog_ping(wdd);
590 mutex_unlock(&wd_data->lock);
599 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
600 * @file: file handle to the device
601 * @cmd: watchdog command
602 * @arg: argument pointer
604 * The watchdog API defines a common set of functions for all watchdogs
605 * according to their available features.
608 static long watchdog_ioctl(struct file *file, unsigned int cmd,
611 struct watchdog_core_data *wd_data = file->private_data;
612 void __user *argp = (void __user *)arg;
613 struct watchdog_device *wdd;
614 int __user *p = argp;
618 mutex_lock(&wd_data->lock);
626 err = watchdog_ioctl_op(wdd, cmd, arg);
627 if (err != -ENOIOCTLCMD)
631 case WDIOC_GETSUPPORT:
632 err = copy_to_user(argp, wdd->info,
633 sizeof(struct watchdog_info)) ? -EFAULT : 0;
635 case WDIOC_GETSTATUS:
636 val = watchdog_get_status(wdd);
637 err = put_user(val, p);
639 case WDIOC_GETBOOTSTATUS:
640 err = put_user(wdd->bootstatus, p);
642 case WDIOC_SETOPTIONS:
643 if (get_user(val, p)) {
647 if (val & WDIOS_DISABLECARD) {
648 err = watchdog_stop(wdd);
652 if (val & WDIOS_ENABLECARD)
653 err = watchdog_start(wdd);
655 case WDIOC_KEEPALIVE:
656 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
660 err = watchdog_ping(wdd);
662 case WDIOC_SETTIMEOUT:
663 if (get_user(val, p)) {
667 err = watchdog_set_timeout(wdd, val);
670 /* If the watchdog is active then we send a keepalive ping
671 * to make sure that the watchdog keep's running (and if
672 * possible that it takes the new timeout) */
673 err = watchdog_ping(wdd);
677 case WDIOC_GETTIMEOUT:
678 /* timeout == 0 means that we don't know the timeout */
679 if (wdd->timeout == 0) {
683 err = put_user(wdd->timeout, p);
685 case WDIOC_GETTIMELEFT:
686 err = watchdog_get_timeleft(wdd, &val);
689 err = put_user(val, p);
691 case WDIOC_SETPRETIMEOUT:
692 if (get_user(val, p)) {
696 err = watchdog_set_pretimeout(wdd, val);
698 case WDIOC_GETPRETIMEOUT:
699 err = put_user(wdd->pretimeout, p);
707 mutex_unlock(&wd_data->lock);
712 * watchdog_open: open the /dev/watchdog* devices.
713 * @inode: inode of device
714 * @file: file handle to device
716 * When the /dev/watchdog* device gets opened, we start the watchdog.
717 * Watch out: the /dev/watchdog device is single open, so we make sure
718 * it can only be opened once.
721 static int watchdog_open(struct inode *inode, struct file *file)
723 struct watchdog_core_data *wd_data;
724 struct watchdog_device *wdd;
727 /* Get the corresponding watchdog device */
728 if (imajor(inode) == MISC_MAJOR)
729 wd_data = old_wd_data;
731 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
734 /* the watchdog is single open! */
735 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
741 * If the /dev/watchdog device is open, we don't want the module
744 if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
749 err = watchdog_start(wdd);
753 file->private_data = wd_data;
755 if (!watchdog_hw_running(wdd))
756 kref_get(&wd_data->kref);
758 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
759 return nonseekable_open(inode, file);
762 module_put(wd_data->wdd->ops->owner);
764 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
768 static void watchdog_core_data_release(struct kref *kref)
770 struct watchdog_core_data *wd_data;
772 wd_data = container_of(kref, struct watchdog_core_data, kref);
778 * watchdog_release: release the watchdog device.
779 * @inode: inode of device
780 * @file: file handle to device
782 * This is the code for when /dev/watchdog gets closed. We will only
783 * stop the watchdog when we have received the magic char (and nowayout
784 * was not set), else the watchdog will keep running.
787 static int watchdog_release(struct inode *inode, struct file *file)
789 struct watchdog_core_data *wd_data = file->private_data;
790 struct watchdog_device *wdd;
794 mutex_lock(&wd_data->lock);
801 * We only stop the watchdog if we received the magic character
802 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
803 * watchdog_stop will fail.
805 if (!test_bit(WDOG_ACTIVE, &wdd->status))
807 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
808 !(wdd->info->options & WDIOF_MAGICCLOSE))
809 err = watchdog_stop(wdd);
811 /* If the watchdog was not stopped, send a keepalive ping */
813 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
817 watchdog_update_worker(wdd);
819 /* make sure that /dev/watchdog can be re-opened */
820 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
823 running = wdd && watchdog_hw_running(wdd);
824 mutex_unlock(&wd_data->lock);
826 * Allow the owner module to be unloaded again unless the watchdog
827 * is still running. If the watchdog is still running, it can not
828 * be stopped, and its driver must not be unloaded.
831 module_put(wd_data->cdev.owner);
832 kref_put(&wd_data->kref, watchdog_core_data_release);
837 static const struct file_operations watchdog_fops = {
838 .owner = THIS_MODULE,
839 .write = watchdog_write,
840 .unlocked_ioctl = watchdog_ioctl,
841 .open = watchdog_open,
842 .release = watchdog_release,
845 static struct miscdevice watchdog_miscdev = {
846 .minor = WATCHDOG_MINOR,
848 .fops = &watchdog_fops,
852 * watchdog_cdev_register: register watchdog character device
853 * @wdd: watchdog device
854 * @devno: character device number
856 * Register a watchdog character device including handling the legacy
857 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
858 * thus we set it up like that.
861 static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
863 struct watchdog_core_data *wd_data;
866 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
869 kref_init(&wd_data->kref);
870 mutex_init(&wd_data->lock);
873 wdd->wd_data = wd_data;
878 INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
881 old_wd_data = wd_data;
882 watchdog_miscdev.parent = wdd->parent;
883 err = misc_register(&watchdog_miscdev);
885 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
886 wdd->info->identity, WATCHDOG_MINOR, err);
888 pr_err("%s: a legacy watchdog module is probably present.\n",
889 wdd->info->identity);
896 /* Fill in the data structures */
897 cdev_init(&wd_data->cdev, &watchdog_fops);
898 wd_data->cdev.owner = wdd->ops->owner;
901 err = cdev_add(&wd_data->cdev, devno, 1);
903 pr_err("watchdog%d unable to add device %d:%d\n",
904 wdd->id, MAJOR(watchdog_devt), wdd->id);
906 misc_deregister(&watchdog_miscdev);
908 kref_put(&wd_data->kref, watchdog_core_data_release);
913 /* Record time of most recent heartbeat as 'just before now'. */
914 wd_data->last_hw_keepalive = jiffies - 1;
917 * If the watchdog is running, prevent its driver from being unloaded,
918 * and schedule an immediate ping.
920 if (watchdog_hw_running(wdd)) {
921 __module_get(wdd->ops->owner);
922 kref_get(&wd_data->kref);
923 queue_delayed_work(watchdog_wq, &wd_data->work, 0);
930 * watchdog_cdev_unregister: unregister watchdog character device
931 * @watchdog: watchdog device
933 * Unregister watchdog character device and if needed the legacy
934 * /dev/watchdog device.
937 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
939 struct watchdog_core_data *wd_data = wdd->wd_data;
941 cdev_del(&wd_data->cdev);
943 misc_deregister(&watchdog_miscdev);
947 mutex_lock(&wd_data->lock);
950 mutex_unlock(&wd_data->lock);
952 cancel_delayed_work_sync(&wd_data->work);
954 kref_put(&wd_data->kref, watchdog_core_data_release);
957 static struct class watchdog_class = {
959 .owner = THIS_MODULE,
960 .dev_groups = wdt_groups,
964 * watchdog_dev_register: register a watchdog device
965 * @wdd: watchdog device
967 * Register a watchdog device including handling the legacy
968 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
969 * thus we set it up like that.
972 int watchdog_dev_register(struct watchdog_device *wdd)
978 devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
980 ret = watchdog_cdev_register(wdd, devno);
984 dev = device_create_with_groups(&watchdog_class, wdd->parent,
985 devno, wdd, wdd->groups,
986 "watchdog%d", wdd->id);
988 watchdog_cdev_unregister(wdd);
996 * watchdog_dev_unregister: unregister a watchdog device
997 * @watchdog: watchdog device
999 * Unregister watchdog device and if needed the legacy
1000 * /dev/watchdog device.
1003 void watchdog_dev_unregister(struct watchdog_device *wdd)
1005 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
1006 watchdog_cdev_unregister(wdd);
1010 * watchdog_dev_init: init dev part of watchdog core
1012 * Allocate a range of chardev nodes to use for watchdog devices
1015 int __init watchdog_dev_init(void)
1019 watchdog_wq = alloc_workqueue("watchdogd",
1020 WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
1022 pr_err("Failed to create watchdog workqueue\n");
1026 err = class_register(&watchdog_class);
1028 pr_err("couldn't register class\n");
1032 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1034 pr_err("watchdog: unable to allocate char dev region\n");
1041 class_unregister(&watchdog_class);
1043 destroy_workqueue(watchdog_wq);
1048 * watchdog_dev_exit: exit dev part of watchdog core
1050 * Release the range of chardev nodes used for watchdog devices
1053 void __exit watchdog_dev_exit(void)
1055 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1056 class_unregister(&watchdog_class);
1057 destroy_workqueue(watchdog_wq);