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/miscdevice.h> /* For handling misc devices */
42 #include <linux/module.h> /* For module stuff/... */
43 #include <linux/mutex.h> /* For mutexes */
44 #include <linux/slab.h> /* For memory functions */
45 #include <linux/types.h> /* For standard types (like size_t) */
46 #include <linux/watchdog.h> /* For watchdog specific items */
47 #include <linux/workqueue.h> /* For workqueue */
48 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */
50 #include "watchdog_core.h"
51 #include "watchdog_pretimeout.h"
54 * struct watchdog_core_data - watchdog core internal data
55 * @dev: The watchdog's internal device
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 wd_data->last_hw_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_available_governors_show(struct device *dev,
493 struct device_attribute *attr, char *buf)
495 return watchdog_pretimeout_available_governors_get(buf);
497 static DEVICE_ATTR_RO(pretimeout_available_governors);
499 static ssize_t pretimeout_governor_show(struct device *dev,
500 struct device_attribute *attr,
503 struct watchdog_device *wdd = dev_get_drvdata(dev);
505 return watchdog_pretimeout_governor_get(wdd, buf);
508 static ssize_t pretimeout_governor_store(struct device *dev,
509 struct device_attribute *attr,
510 const char *buf, size_t count)
512 struct watchdog_device *wdd = dev_get_drvdata(dev);
513 int ret = watchdog_pretimeout_governor_set(wdd, buf);
520 static DEVICE_ATTR_RW(pretimeout_governor);
522 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
525 struct device *dev = container_of(kobj, struct device, kobj);
526 struct watchdog_device *wdd = dev_get_drvdata(dev);
527 umode_t mode = attr->mode;
529 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
531 else if (attr == &dev_attr_pretimeout.attr &&
532 !(wdd->info->options & WDIOF_PRETIMEOUT))
534 else if ((attr == &dev_attr_pretimeout_governor.attr ||
535 attr == &dev_attr_pretimeout_available_governors.attr) &&
536 (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
537 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
542 static struct attribute *wdt_attrs[] = {
543 &dev_attr_state.attr,
544 &dev_attr_identity.attr,
545 &dev_attr_timeout.attr,
546 &dev_attr_pretimeout.attr,
547 &dev_attr_timeleft.attr,
548 &dev_attr_bootstatus.attr,
549 &dev_attr_status.attr,
550 &dev_attr_nowayout.attr,
551 &dev_attr_pretimeout_governor.attr,
552 &dev_attr_pretimeout_available_governors.attr,
556 static const struct attribute_group wdt_group = {
558 .is_visible = wdt_is_visible,
560 __ATTRIBUTE_GROUPS(wdt);
562 #define wdt_groups NULL
566 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
567 * @wdd: the watchdog device to do the ioctl on
568 * @cmd: watchdog command
569 * @arg: argument pointer
571 * The caller must hold wd_data->lock.
574 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
577 if (!wdd->ops->ioctl)
580 return wdd->ops->ioctl(wdd, cmd, arg);
584 * watchdog_write: writes to the watchdog.
585 * @file: file from VFS
586 * @data: user address of data
587 * @len: length of data
588 * @ppos: pointer to the file offset
590 * A write to a watchdog device is defined as a keepalive ping.
591 * Writing the magic 'V' sequence allows the next close to turn
592 * off the watchdog (if 'nowayout' is not set).
595 static ssize_t watchdog_write(struct file *file, const char __user *data,
596 size_t len, loff_t *ppos)
598 struct watchdog_core_data *wd_data = file->private_data;
599 struct watchdog_device *wdd;
608 * Note: just in case someone wrote the magic character
611 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
613 /* scan to see whether or not we got the magic character */
614 for (i = 0; i != len; i++) {
615 if (get_user(c, data + i))
618 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
621 /* someone wrote to us, so we send the watchdog a keepalive ping */
624 mutex_lock(&wd_data->lock);
627 err = watchdog_ping(wdd);
628 mutex_unlock(&wd_data->lock);
637 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
638 * @file: file handle to the device
639 * @cmd: watchdog command
640 * @arg: argument pointer
642 * The watchdog API defines a common set of functions for all watchdogs
643 * according to their available features.
646 static long watchdog_ioctl(struct file *file, unsigned int cmd,
649 struct watchdog_core_data *wd_data = file->private_data;
650 void __user *argp = (void __user *)arg;
651 struct watchdog_device *wdd;
652 int __user *p = argp;
656 mutex_lock(&wd_data->lock);
664 err = watchdog_ioctl_op(wdd, cmd, arg);
665 if (err != -ENOIOCTLCMD)
669 case WDIOC_GETSUPPORT:
670 err = copy_to_user(argp, wdd->info,
671 sizeof(struct watchdog_info)) ? -EFAULT : 0;
673 case WDIOC_GETSTATUS:
674 val = watchdog_get_status(wdd);
675 err = put_user(val, p);
677 case WDIOC_GETBOOTSTATUS:
678 err = put_user(wdd->bootstatus, p);
680 case WDIOC_SETOPTIONS:
681 if (get_user(val, p)) {
685 if (val & WDIOS_DISABLECARD) {
686 err = watchdog_stop(wdd);
690 if (val & WDIOS_ENABLECARD)
691 err = watchdog_start(wdd);
693 case WDIOC_KEEPALIVE:
694 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
698 err = watchdog_ping(wdd);
700 case WDIOC_SETTIMEOUT:
701 if (get_user(val, p)) {
705 err = watchdog_set_timeout(wdd, val);
708 /* If the watchdog is active then we send a keepalive ping
709 * to make sure that the watchdog keep's running (and if
710 * possible that it takes the new timeout) */
711 err = watchdog_ping(wdd);
715 case WDIOC_GETTIMEOUT:
716 /* timeout == 0 means that we don't know the timeout */
717 if (wdd->timeout == 0) {
721 err = put_user(wdd->timeout, p);
723 case WDIOC_GETTIMELEFT:
724 err = watchdog_get_timeleft(wdd, &val);
727 err = put_user(val, p);
729 case WDIOC_SETPRETIMEOUT:
730 if (get_user(val, p)) {
734 err = watchdog_set_pretimeout(wdd, val);
736 case WDIOC_GETPRETIMEOUT:
737 err = put_user(wdd->pretimeout, p);
745 mutex_unlock(&wd_data->lock);
750 * watchdog_open: open the /dev/watchdog* devices.
751 * @inode: inode of device
752 * @file: file handle to device
754 * When the /dev/watchdog* device gets opened, we start the watchdog.
755 * Watch out: the /dev/watchdog device is single open, so we make sure
756 * it can only be opened once.
759 static int watchdog_open(struct inode *inode, struct file *file)
761 struct watchdog_core_data *wd_data;
762 struct watchdog_device *wdd;
766 /* Get the corresponding watchdog device */
767 if (imajor(inode) == MISC_MAJOR)
768 wd_data = old_wd_data;
770 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
773 /* the watchdog is single open! */
774 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
780 * If the /dev/watchdog device is open, we don't want the module
783 hw_running = watchdog_hw_running(wdd);
784 if (!hw_running && !try_module_get(wdd->ops->owner)) {
789 err = watchdog_start(wdd);
793 file->private_data = wd_data;
796 get_device(&wd_data->dev);
798 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
799 return nonseekable_open(inode, file);
802 module_put(wd_data->wdd->ops->owner);
804 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
808 static void watchdog_core_data_release(struct device *dev)
810 struct watchdog_core_data *wd_data;
812 wd_data = container_of(dev, struct watchdog_core_data, dev);
818 * watchdog_release: release the watchdog device.
819 * @inode: inode of device
820 * @file: file handle to device
822 * This is the code for when /dev/watchdog gets closed. We will only
823 * stop the watchdog when we have received the magic char (and nowayout
824 * was not set), else the watchdog will keep running.
827 static int watchdog_release(struct inode *inode, struct file *file)
829 struct watchdog_core_data *wd_data = file->private_data;
830 struct watchdog_device *wdd;
834 mutex_lock(&wd_data->lock);
841 * We only stop the watchdog if we received the magic character
842 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
843 * watchdog_stop will fail.
845 if (!test_bit(WDOG_ACTIVE, &wdd->status))
847 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
848 !(wdd->info->options & WDIOF_MAGICCLOSE))
849 err = watchdog_stop(wdd);
851 /* If the watchdog was not stopped, send a keepalive ping */
853 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
857 watchdog_update_worker(wdd);
859 /* make sure that /dev/watchdog can be re-opened */
860 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
863 running = wdd && watchdog_hw_running(wdd);
864 mutex_unlock(&wd_data->lock);
866 * Allow the owner module to be unloaded again unless the watchdog
867 * is still running. If the watchdog is still running, it can not
868 * be stopped, and its driver must not be unloaded.
871 module_put(wd_data->cdev.owner);
872 put_device(&wd_data->dev);
877 static const struct file_operations watchdog_fops = {
878 .owner = THIS_MODULE,
879 .write = watchdog_write,
880 .unlocked_ioctl = watchdog_ioctl,
881 .open = watchdog_open,
882 .release = watchdog_release,
885 static struct miscdevice watchdog_miscdev = {
886 .minor = WATCHDOG_MINOR,
888 .fops = &watchdog_fops,
891 static struct class watchdog_class = {
893 .owner = THIS_MODULE,
894 .dev_groups = wdt_groups,
898 * watchdog_cdev_register: register watchdog character device
899 * @wdd: watchdog device
901 * Register a watchdog character device including handling the legacy
902 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
903 * thus we set it up like that.
906 static int watchdog_cdev_register(struct watchdog_device *wdd)
908 struct watchdog_core_data *wd_data;
911 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
914 mutex_init(&wd_data->lock);
917 wdd->wd_data = wd_data;
922 INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
925 old_wd_data = wd_data;
926 watchdog_miscdev.parent = wdd->parent;
927 err = misc_register(&watchdog_miscdev);
929 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
930 wdd->info->identity, WATCHDOG_MINOR, err);
932 pr_err("%s: a legacy watchdog module is probably present.\n",
933 wdd->info->identity);
940 device_initialize(&wd_data->dev);
941 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
942 wd_data->dev.class = &watchdog_class;
943 wd_data->dev.parent = wdd->parent;
944 wd_data->dev.groups = wdd->groups;
945 wd_data->dev.release = watchdog_core_data_release;
946 dev_set_drvdata(&wd_data->dev, wdd);
947 dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
949 /* Fill in the data structures */
950 cdev_init(&wd_data->cdev, &watchdog_fops);
953 err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
955 pr_err("watchdog%d unable to add device %d:%d\n",
956 wdd->id, MAJOR(watchdog_devt), wdd->id);
958 misc_deregister(&watchdog_miscdev);
960 put_device(&wd_data->dev);
965 wd_data->cdev.owner = wdd->ops->owner;
967 /* Record time of most recent heartbeat as 'just before now'. */
968 wd_data->last_hw_keepalive = jiffies - 1;
971 * If the watchdog is running, prevent its driver from being unloaded,
972 * and schedule an immediate ping.
974 if (watchdog_hw_running(wdd)) {
975 __module_get(wdd->ops->owner);
976 get_device(&wd_data->dev);
977 queue_delayed_work(watchdog_wq, &wd_data->work, 0);
984 * watchdog_cdev_unregister: unregister watchdog character device
985 * @watchdog: watchdog device
987 * Unregister watchdog character device and if needed the legacy
988 * /dev/watchdog device.
991 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
993 struct watchdog_core_data *wd_data = wdd->wd_data;
995 cdev_device_del(&wd_data->cdev, &wd_data->dev);
997 misc_deregister(&watchdog_miscdev);
1001 mutex_lock(&wd_data->lock);
1002 wd_data->wdd = NULL;
1003 wdd->wd_data = NULL;
1004 mutex_unlock(&wd_data->lock);
1006 cancel_delayed_work_sync(&wd_data->work);
1008 put_device(&wd_data->dev);
1012 * watchdog_dev_register: register a watchdog device
1013 * @wdd: watchdog device
1015 * Register a watchdog device including handling the legacy
1016 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1017 * thus we set it up like that.
1020 int watchdog_dev_register(struct watchdog_device *wdd)
1024 ret = watchdog_cdev_register(wdd);
1028 ret = watchdog_register_pretimeout(wdd);
1030 watchdog_cdev_unregister(wdd);
1037 * watchdog_dev_unregister: unregister a watchdog device
1038 * @watchdog: watchdog device
1040 * Unregister watchdog device and if needed the legacy
1041 * /dev/watchdog device.
1044 void watchdog_dev_unregister(struct watchdog_device *wdd)
1046 watchdog_unregister_pretimeout(wdd);
1047 watchdog_cdev_unregister(wdd);
1051 * watchdog_dev_init: init dev part of watchdog core
1053 * Allocate a range of chardev nodes to use for watchdog devices
1056 int __init watchdog_dev_init(void)
1060 watchdog_wq = alloc_workqueue("watchdogd",
1061 WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
1063 pr_err("Failed to create watchdog workqueue\n");
1067 err = class_register(&watchdog_class);
1069 pr_err("couldn't register class\n");
1073 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1075 pr_err("watchdog: unable to allocate char dev region\n");
1082 class_unregister(&watchdog_class);
1084 destroy_workqueue(watchdog_wq);
1089 * watchdog_dev_exit: exit dev part of watchdog core
1091 * Release the range of chardev nodes used for watchdog devices
1094 void __exit watchdog_dev_exit(void)
1096 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1097 class_unregister(&watchdog_class);
1098 destroy_workqueue(watchdog_wq);