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"
52 #include "watchdog_pretimeout.h"
55 * struct watchdog_core_data - watchdog core internal data
56 * @kref: Reference count.
57 * @cdev: The watchdog's Character device.
58 * @wdd: Pointer to watchdog device.
59 * @lock: Lock for watchdog core.
60 * @status: Watchdog core internal status bits.
62 struct watchdog_core_data {
65 struct watchdog_device *wdd;
67 unsigned long last_keepalive;
68 unsigned long last_hw_keepalive;
69 struct delayed_work work;
70 unsigned long status; /* Internal status bits */
71 #define _WDOG_DEV_OPEN 0 /* Opened ? */
72 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
73 #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
76 /* the dev_t structure to store the dynamically allocated watchdog devices */
77 static dev_t watchdog_devt;
78 /* Reference to watchdog device behind /dev/watchdog */
79 static struct watchdog_core_data *old_wd_data;
81 static struct workqueue_struct *watchdog_wq;
83 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
85 /* All variables in milli-seconds */
86 unsigned int hm = wdd->max_hw_heartbeat_ms;
87 unsigned int t = wdd->timeout * 1000;
90 * A worker to generate heartbeat requests is needed if all of the
91 * following conditions are true.
92 * - Userspace activated the watchdog.
93 * - The driver provided a value for the maximum hardware timeout, and
94 * thus is aware that the framework supports generating heartbeat
96 * - Userspace requests a longer timeout than the hardware can handle.
98 * Alternatively, if userspace has not opened the watchdog
99 * device, we take care of feeding the watchdog if it is
102 return (hm && watchdog_active(wdd) && t > hm) ||
103 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
106 static long watchdog_next_keepalive(struct watchdog_device *wdd)
108 struct watchdog_core_data *wd_data = wdd->wd_data;
109 unsigned int timeout_ms = wdd->timeout * 1000;
110 unsigned long keepalive_interval;
111 unsigned long last_heartbeat;
112 unsigned long virt_timeout;
113 unsigned int hw_heartbeat_ms;
115 virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
116 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
117 keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);
119 if (!watchdog_active(wdd))
120 return keepalive_interval;
123 * To ensure that the watchdog times out wdd->timeout seconds
124 * after the most recent ping from userspace, the last
125 * worker ping has to come in hw_heartbeat_ms before this timeout.
127 last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
128 return min_t(long, last_heartbeat - jiffies, keepalive_interval);
131 static inline void watchdog_update_worker(struct watchdog_device *wdd)
133 struct watchdog_core_data *wd_data = wdd->wd_data;
135 if (watchdog_need_worker(wdd)) {
136 long t = watchdog_next_keepalive(wdd);
139 mod_delayed_work(watchdog_wq, &wd_data->work, t);
141 cancel_delayed_work(&wd_data->work);
145 static int __watchdog_ping(struct watchdog_device *wdd)
147 struct watchdog_core_data *wd_data = wdd->wd_data;
148 unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
149 msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
152 if (time_is_after_jiffies(earliest_keepalive)) {
153 mod_delayed_work(watchdog_wq, &wd_data->work,
154 earliest_keepalive - jiffies);
158 wd_data->last_hw_keepalive = jiffies;
161 err = wdd->ops->ping(wdd); /* ping the watchdog */
163 err = wdd->ops->start(wdd); /* restart watchdog */
165 watchdog_update_worker(wdd);
171 * watchdog_ping: ping the watchdog.
172 * @wdd: the watchdog device to ping
174 * The caller must hold wd_data->lock.
176 * If the watchdog has no own ping operation then it needs to be
177 * restarted via the start operation. This wrapper function does
179 * We only ping when the watchdog device is running.
182 static int watchdog_ping(struct watchdog_device *wdd)
184 struct watchdog_core_data *wd_data = wdd->wd_data;
186 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
189 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
191 wd_data->last_keepalive = jiffies;
192 return __watchdog_ping(wdd);
195 static void watchdog_ping_work(struct work_struct *work)
197 struct watchdog_core_data *wd_data;
198 struct watchdog_device *wdd;
200 wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
203 mutex_lock(&wd_data->lock);
205 if (wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd)))
206 __watchdog_ping(wdd);
207 mutex_unlock(&wd_data->lock);
211 * watchdog_start: wrapper to start the watchdog.
212 * @wdd: the watchdog device to start
214 * The caller must hold wd_data->lock.
216 * Start the watchdog if it is not active and mark it active.
217 * This function returns zero on success or a negative errno code for
221 static int watchdog_start(struct watchdog_device *wdd)
223 struct watchdog_core_data *wd_data = wdd->wd_data;
224 unsigned long started_at;
227 if (watchdog_active(wdd))
230 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
232 started_at = jiffies;
233 if (watchdog_hw_running(wdd) && wdd->ops->ping)
234 err = wdd->ops->ping(wdd);
236 err = wdd->ops->start(wdd);
238 set_bit(WDOG_ACTIVE, &wdd->status);
239 wd_data->last_keepalive = started_at;
240 watchdog_update_worker(wdd);
247 * watchdog_stop: wrapper to stop the watchdog.
248 * @wdd: the watchdog device to stop
250 * The caller must hold wd_data->lock.
252 * Stop the watchdog if it is still active and unmark it active.
253 * This function returns zero on success or a negative errno code for
255 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
258 static int watchdog_stop(struct watchdog_device *wdd)
262 if (!watchdog_active(wdd))
265 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
266 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
271 if (wdd->ops->stop) {
272 clear_bit(WDOG_HW_RUNNING, &wdd->status);
273 err = wdd->ops->stop(wdd);
275 set_bit(WDOG_HW_RUNNING, &wdd->status);
279 clear_bit(WDOG_ACTIVE, &wdd->status);
280 watchdog_update_worker(wdd);
287 * watchdog_get_status: wrapper to get the watchdog status
288 * @wdd: the watchdog device to get the status from
290 * The caller must hold wd_data->lock.
292 * Get the watchdog's status flags.
295 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
297 struct watchdog_core_data *wd_data = wdd->wd_data;
300 if (wdd->ops->status)
301 status = wdd->ops->status(wdd);
303 status = wdd->bootstatus & (WDIOF_CARDRESET |
311 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
312 status |= WDIOF_MAGICCLOSE;
314 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
315 status |= WDIOF_KEEPALIVEPING;
321 * watchdog_set_timeout: set the watchdog timer timeout
322 * @wdd: the watchdog device to set the timeout for
323 * @timeout: timeout to set in seconds
325 * The caller must hold wd_data->lock.
328 static int watchdog_set_timeout(struct watchdog_device *wdd,
329 unsigned int timeout)
333 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
336 if (watchdog_timeout_invalid(wdd, timeout))
339 if (wdd->ops->set_timeout) {
340 err = wdd->ops->set_timeout(wdd, timeout);
342 wdd->timeout = timeout;
343 /* Disable pretimeout if it doesn't fit the new timeout */
344 if (wdd->pretimeout >= wdd->timeout)
348 watchdog_update_worker(wdd);
354 * watchdog_set_pretimeout: set the watchdog timer pretimeout
355 * @wdd: the watchdog device to set the timeout for
356 * @timeout: pretimeout to set in seconds
359 static int watchdog_set_pretimeout(struct watchdog_device *wdd,
360 unsigned int timeout)
364 if (!(wdd->info->options & WDIOF_PRETIMEOUT))
367 if (watchdog_pretimeout_invalid(wdd, timeout))
370 if (wdd->ops->set_pretimeout)
371 err = wdd->ops->set_pretimeout(wdd, timeout);
373 wdd->pretimeout = timeout;
379 * watchdog_get_timeleft: wrapper to get the time left before a reboot
380 * @wdd: the watchdog device to get the remaining time from
381 * @timeleft: the time that's left
383 * The caller must hold wd_data->lock.
385 * Get the time before a watchdog will reboot (if not pinged).
388 static int watchdog_get_timeleft(struct watchdog_device *wdd,
389 unsigned int *timeleft)
393 if (!wdd->ops->get_timeleft)
396 *timeleft = wdd->ops->get_timeleft(wdd);
401 #ifdef CONFIG_WATCHDOG_SYSFS
402 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
405 struct watchdog_device *wdd = dev_get_drvdata(dev);
407 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
409 static DEVICE_ATTR_RO(nowayout);
411 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
414 struct watchdog_device *wdd = dev_get_drvdata(dev);
415 struct watchdog_core_data *wd_data = wdd->wd_data;
418 mutex_lock(&wd_data->lock);
419 status = watchdog_get_status(wdd);
420 mutex_unlock(&wd_data->lock);
422 return sprintf(buf, "0x%x\n", status);
424 static DEVICE_ATTR_RO(status);
426 static ssize_t bootstatus_show(struct device *dev,
427 struct device_attribute *attr, char *buf)
429 struct watchdog_device *wdd = dev_get_drvdata(dev);
431 return sprintf(buf, "%u\n", wdd->bootstatus);
433 static DEVICE_ATTR_RO(bootstatus);
435 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
438 struct watchdog_device *wdd = dev_get_drvdata(dev);
439 struct watchdog_core_data *wd_data = wdd->wd_data;
443 mutex_lock(&wd_data->lock);
444 status = watchdog_get_timeleft(wdd, &val);
445 mutex_unlock(&wd_data->lock);
447 status = sprintf(buf, "%u\n", val);
451 static DEVICE_ATTR_RO(timeleft);
453 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
456 struct watchdog_device *wdd = dev_get_drvdata(dev);
458 return sprintf(buf, "%u\n", wdd->timeout);
460 static DEVICE_ATTR_RO(timeout);
462 static ssize_t pretimeout_show(struct device *dev,
463 struct device_attribute *attr, char *buf)
465 struct watchdog_device *wdd = dev_get_drvdata(dev);
467 return sprintf(buf, "%u\n", wdd->pretimeout);
469 static DEVICE_ATTR_RO(pretimeout);
471 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
474 struct watchdog_device *wdd = dev_get_drvdata(dev);
476 return sprintf(buf, "%s\n", wdd->info->identity);
478 static DEVICE_ATTR_RO(identity);
480 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
483 struct watchdog_device *wdd = dev_get_drvdata(dev);
485 if (watchdog_active(wdd))
486 return sprintf(buf, "active\n");
488 return sprintf(buf, "inactive\n");
490 static DEVICE_ATTR_RO(state);
492 static ssize_t pretimeout_governor_show(struct device *dev,
493 struct device_attribute *attr,
496 struct watchdog_device *wdd = dev_get_drvdata(dev);
498 return watchdog_pretimeout_governor_get(wdd, buf);
500 static DEVICE_ATTR_RO(pretimeout_governor);
502 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
505 struct device *dev = container_of(kobj, struct device, kobj);
506 struct watchdog_device *wdd = dev_get_drvdata(dev);
507 umode_t mode = attr->mode;
509 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
511 else if (attr == &dev_attr_pretimeout.attr &&
512 !(wdd->info->options & WDIOF_PRETIMEOUT))
514 else if (attr == &dev_attr_pretimeout_governor.attr &&
515 (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
516 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
521 static struct attribute *wdt_attrs[] = {
522 &dev_attr_state.attr,
523 &dev_attr_identity.attr,
524 &dev_attr_timeout.attr,
525 &dev_attr_pretimeout.attr,
526 &dev_attr_timeleft.attr,
527 &dev_attr_bootstatus.attr,
528 &dev_attr_status.attr,
529 &dev_attr_nowayout.attr,
530 &dev_attr_pretimeout_governor.attr,
534 static const struct attribute_group wdt_group = {
536 .is_visible = wdt_is_visible,
538 __ATTRIBUTE_GROUPS(wdt);
540 #define wdt_groups NULL
544 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
545 * @wdd: the watchdog device to do the ioctl on
546 * @cmd: watchdog command
547 * @arg: argument pointer
549 * The caller must hold wd_data->lock.
552 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
555 if (!wdd->ops->ioctl)
558 return wdd->ops->ioctl(wdd, cmd, arg);
562 * watchdog_write: writes to the watchdog.
563 * @file: file from VFS
564 * @data: user address of data
565 * @len: length of data
566 * @ppos: pointer to the file offset
568 * A write to a watchdog device is defined as a keepalive ping.
569 * Writing the magic 'V' sequence allows the next close to turn
570 * off the watchdog (if 'nowayout' is not set).
573 static ssize_t watchdog_write(struct file *file, const char __user *data,
574 size_t len, loff_t *ppos)
576 struct watchdog_core_data *wd_data = file->private_data;
577 struct watchdog_device *wdd;
586 * Note: just in case someone wrote the magic character
589 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
591 /* scan to see whether or not we got the magic character */
592 for (i = 0; i != len; i++) {
593 if (get_user(c, data + i))
596 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
599 /* someone wrote to us, so we send the watchdog a keepalive ping */
602 mutex_lock(&wd_data->lock);
605 err = watchdog_ping(wdd);
606 mutex_unlock(&wd_data->lock);
615 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
616 * @file: file handle to the device
617 * @cmd: watchdog command
618 * @arg: argument pointer
620 * The watchdog API defines a common set of functions for all watchdogs
621 * according to their available features.
624 static long watchdog_ioctl(struct file *file, unsigned int cmd,
627 struct watchdog_core_data *wd_data = file->private_data;
628 void __user *argp = (void __user *)arg;
629 struct watchdog_device *wdd;
630 int __user *p = argp;
634 mutex_lock(&wd_data->lock);
642 err = watchdog_ioctl_op(wdd, cmd, arg);
643 if (err != -ENOIOCTLCMD)
647 case WDIOC_GETSUPPORT:
648 err = copy_to_user(argp, wdd->info,
649 sizeof(struct watchdog_info)) ? -EFAULT : 0;
651 case WDIOC_GETSTATUS:
652 val = watchdog_get_status(wdd);
653 err = put_user(val, p);
655 case WDIOC_GETBOOTSTATUS:
656 err = put_user(wdd->bootstatus, p);
658 case WDIOC_SETOPTIONS:
659 if (get_user(val, p)) {
663 if (val & WDIOS_DISABLECARD) {
664 err = watchdog_stop(wdd);
668 if (val & WDIOS_ENABLECARD)
669 err = watchdog_start(wdd);
671 case WDIOC_KEEPALIVE:
672 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
676 err = watchdog_ping(wdd);
678 case WDIOC_SETTIMEOUT:
679 if (get_user(val, p)) {
683 err = watchdog_set_timeout(wdd, val);
686 /* If the watchdog is active then we send a keepalive ping
687 * to make sure that the watchdog keep's running (and if
688 * possible that it takes the new timeout) */
689 err = watchdog_ping(wdd);
693 case WDIOC_GETTIMEOUT:
694 /* timeout == 0 means that we don't know the timeout */
695 if (wdd->timeout == 0) {
699 err = put_user(wdd->timeout, p);
701 case WDIOC_GETTIMELEFT:
702 err = watchdog_get_timeleft(wdd, &val);
705 err = put_user(val, p);
707 case WDIOC_SETPRETIMEOUT:
708 if (get_user(val, p)) {
712 err = watchdog_set_pretimeout(wdd, val);
714 case WDIOC_GETPRETIMEOUT:
715 err = put_user(wdd->pretimeout, p);
723 mutex_unlock(&wd_data->lock);
728 * watchdog_open: open the /dev/watchdog* devices.
729 * @inode: inode of device
730 * @file: file handle to device
732 * When the /dev/watchdog* device gets opened, we start the watchdog.
733 * Watch out: the /dev/watchdog device is single open, so we make sure
734 * it can only be opened once.
737 static int watchdog_open(struct inode *inode, struct file *file)
739 struct watchdog_core_data *wd_data;
740 struct watchdog_device *wdd;
743 /* Get the corresponding watchdog device */
744 if (imajor(inode) == MISC_MAJOR)
745 wd_data = old_wd_data;
747 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
750 /* the watchdog is single open! */
751 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
757 * If the /dev/watchdog device is open, we don't want the module
760 if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
765 err = watchdog_start(wdd);
769 file->private_data = wd_data;
771 if (!watchdog_hw_running(wdd))
772 kref_get(&wd_data->kref);
774 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
775 return nonseekable_open(inode, file);
778 module_put(wd_data->wdd->ops->owner);
780 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
784 static void watchdog_core_data_release(struct kref *kref)
786 struct watchdog_core_data *wd_data;
788 wd_data = container_of(kref, struct watchdog_core_data, kref);
794 * watchdog_release: release the watchdog device.
795 * @inode: inode of device
796 * @file: file handle to device
798 * This is the code for when /dev/watchdog gets closed. We will only
799 * stop the watchdog when we have received the magic char (and nowayout
800 * was not set), else the watchdog will keep running.
803 static int watchdog_release(struct inode *inode, struct file *file)
805 struct watchdog_core_data *wd_data = file->private_data;
806 struct watchdog_device *wdd;
810 mutex_lock(&wd_data->lock);
817 * We only stop the watchdog if we received the magic character
818 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
819 * watchdog_stop will fail.
821 if (!test_bit(WDOG_ACTIVE, &wdd->status))
823 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
824 !(wdd->info->options & WDIOF_MAGICCLOSE))
825 err = watchdog_stop(wdd);
827 /* If the watchdog was not stopped, send a keepalive ping */
829 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
833 watchdog_update_worker(wdd);
835 /* make sure that /dev/watchdog can be re-opened */
836 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
839 running = wdd && watchdog_hw_running(wdd);
840 mutex_unlock(&wd_data->lock);
842 * Allow the owner module to be unloaded again unless the watchdog
843 * is still running. If the watchdog is still running, it can not
844 * be stopped, and its driver must not be unloaded.
847 module_put(wd_data->cdev.owner);
848 kref_put(&wd_data->kref, watchdog_core_data_release);
853 static const struct file_operations watchdog_fops = {
854 .owner = THIS_MODULE,
855 .write = watchdog_write,
856 .unlocked_ioctl = watchdog_ioctl,
857 .open = watchdog_open,
858 .release = watchdog_release,
861 static struct miscdevice watchdog_miscdev = {
862 .minor = WATCHDOG_MINOR,
864 .fops = &watchdog_fops,
868 * watchdog_cdev_register: register watchdog character device
869 * @wdd: watchdog device
870 * @devno: character device number
872 * Register a watchdog character device including handling the legacy
873 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
874 * thus we set it up like that.
877 static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
879 struct watchdog_core_data *wd_data;
882 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
885 kref_init(&wd_data->kref);
886 mutex_init(&wd_data->lock);
889 wdd->wd_data = wd_data;
894 INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
897 old_wd_data = wd_data;
898 watchdog_miscdev.parent = wdd->parent;
899 err = misc_register(&watchdog_miscdev);
901 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
902 wdd->info->identity, WATCHDOG_MINOR, err);
904 pr_err("%s: a legacy watchdog module is probably present.\n",
905 wdd->info->identity);
912 /* Fill in the data structures */
913 cdev_init(&wd_data->cdev, &watchdog_fops);
914 wd_data->cdev.owner = wdd->ops->owner;
917 err = cdev_add(&wd_data->cdev, devno, 1);
919 pr_err("watchdog%d unable to add device %d:%d\n",
920 wdd->id, MAJOR(watchdog_devt), wdd->id);
922 misc_deregister(&watchdog_miscdev);
924 kref_put(&wd_data->kref, watchdog_core_data_release);
929 /* Record time of most recent heartbeat as 'just before now'. */
930 wd_data->last_hw_keepalive = jiffies - 1;
933 * If the watchdog is running, prevent its driver from being unloaded,
934 * and schedule an immediate ping.
936 if (watchdog_hw_running(wdd)) {
937 __module_get(wdd->ops->owner);
938 kref_get(&wd_data->kref);
939 queue_delayed_work(watchdog_wq, &wd_data->work, 0);
946 * watchdog_cdev_unregister: unregister watchdog character device
947 * @watchdog: watchdog device
949 * Unregister watchdog character device and if needed the legacy
950 * /dev/watchdog device.
953 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
955 struct watchdog_core_data *wd_data = wdd->wd_data;
957 cdev_del(&wd_data->cdev);
959 misc_deregister(&watchdog_miscdev);
963 mutex_lock(&wd_data->lock);
966 mutex_unlock(&wd_data->lock);
968 cancel_delayed_work_sync(&wd_data->work);
970 kref_put(&wd_data->kref, watchdog_core_data_release);
973 static struct class watchdog_class = {
975 .owner = THIS_MODULE,
976 .dev_groups = wdt_groups,
980 * watchdog_dev_register: register a watchdog device
981 * @wdd: watchdog device
983 * Register a watchdog device including handling the legacy
984 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
985 * thus we set it up like that.
988 int watchdog_dev_register(struct watchdog_device *wdd)
994 devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
996 ret = watchdog_cdev_register(wdd, devno);
1000 dev = device_create_with_groups(&watchdog_class, wdd->parent,
1001 devno, wdd, wdd->groups,
1002 "watchdog%d", wdd->id);
1004 watchdog_cdev_unregister(wdd);
1005 return PTR_ERR(dev);
1008 ret = watchdog_register_pretimeout(wdd);
1010 device_destroy(&watchdog_class, devno);
1011 watchdog_cdev_unregister(wdd);
1018 * watchdog_dev_unregister: unregister a watchdog device
1019 * @watchdog: watchdog device
1021 * Unregister watchdog device and if needed the legacy
1022 * /dev/watchdog device.
1025 void watchdog_dev_unregister(struct watchdog_device *wdd)
1027 watchdog_unregister_pretimeout(wdd);
1028 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
1029 watchdog_cdev_unregister(wdd);
1033 * watchdog_dev_init: init dev part of watchdog core
1035 * Allocate a range of chardev nodes to use for watchdog devices
1038 int __init watchdog_dev_init(void)
1042 watchdog_wq = alloc_workqueue("watchdogd",
1043 WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
1045 pr_err("Failed to create watchdog workqueue\n");
1049 err = class_register(&watchdog_class);
1051 pr_err("couldn't register class\n");
1055 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1057 pr_err("watchdog: unable to allocate char dev region\n");
1064 class_unregister(&watchdog_class);
1066 destroy_workqueue(watchdog_wq);
1071 * watchdog_dev_exit: exit dev part of watchdog core
1073 * Release the range of chardev nodes used for watchdog devices
1076 void __exit watchdog_dev_exit(void)
1078 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1079 class_unregister(&watchdog_class);
1080 destroy_workqueue(watchdog_wq);