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 bool handle_boot_enabled =
84 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
86 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
88 /* All variables in milli-seconds */
89 unsigned int hm = wdd->max_hw_heartbeat_ms;
90 unsigned int t = wdd->timeout * 1000;
93 * A worker to generate heartbeat requests is needed if all of the
94 * following conditions are true.
95 * - Userspace activated the watchdog.
96 * - The driver provided a value for the maximum hardware timeout, and
97 * thus is aware that the framework supports generating heartbeat
99 * - Userspace requests a longer timeout than the hardware can handle.
101 * Alternatively, if userspace has not opened the watchdog
102 * device, we take care of feeding the watchdog if it is
105 return (hm && watchdog_active(wdd) && t > hm) ||
106 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
109 static long watchdog_next_keepalive(struct watchdog_device *wdd)
111 struct watchdog_core_data *wd_data = wdd->wd_data;
112 unsigned int timeout_ms = wdd->timeout * 1000;
113 unsigned long keepalive_interval;
114 unsigned long last_heartbeat;
115 unsigned long virt_timeout;
116 unsigned int hw_heartbeat_ms;
118 virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
119 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
120 keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);
122 if (!watchdog_active(wdd))
123 return keepalive_interval;
126 * To ensure that the watchdog times out wdd->timeout seconds
127 * after the most recent ping from userspace, the last
128 * worker ping has to come in hw_heartbeat_ms before this timeout.
130 last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
131 return min_t(long, last_heartbeat - jiffies, keepalive_interval);
134 static inline void watchdog_update_worker(struct watchdog_device *wdd)
136 struct watchdog_core_data *wd_data = wdd->wd_data;
138 if (watchdog_need_worker(wdd)) {
139 long t = watchdog_next_keepalive(wdd);
142 mod_delayed_work(watchdog_wq, &wd_data->work, t);
144 cancel_delayed_work(&wd_data->work);
148 static int __watchdog_ping(struct watchdog_device *wdd)
150 struct watchdog_core_data *wd_data = wdd->wd_data;
151 unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
152 msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
155 if (time_is_after_jiffies(earliest_keepalive)) {
156 mod_delayed_work(watchdog_wq, &wd_data->work,
157 earliest_keepalive - jiffies);
161 wd_data->last_hw_keepalive = jiffies;
164 err = wdd->ops->ping(wdd); /* ping the watchdog */
166 err = wdd->ops->start(wdd); /* restart watchdog */
168 watchdog_update_worker(wdd);
174 * watchdog_ping: ping the watchdog.
175 * @wdd: the watchdog device to ping
177 * The caller must hold wd_data->lock.
179 * If the watchdog has no own ping operation then it needs to be
180 * restarted via the start operation. This wrapper function does
182 * We only ping when the watchdog device is running.
185 static int watchdog_ping(struct watchdog_device *wdd)
187 struct watchdog_core_data *wd_data = wdd->wd_data;
189 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
192 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
194 wd_data->last_keepalive = jiffies;
195 return __watchdog_ping(wdd);
198 static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
200 struct watchdog_device *wdd = wd_data->wdd;
202 return wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd));
205 static void watchdog_ping_work(struct work_struct *work)
207 struct watchdog_core_data *wd_data;
209 wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
212 mutex_lock(&wd_data->lock);
213 if (watchdog_worker_should_ping(wd_data))
214 __watchdog_ping(wd_data->wdd);
215 mutex_unlock(&wd_data->lock);
219 * watchdog_start: wrapper to start the watchdog.
220 * @wdd: the watchdog device to start
222 * The caller must hold wd_data->lock.
224 * Start the watchdog if it is not active and mark it active.
225 * This function returns zero on success or a negative errno code for
229 static int watchdog_start(struct watchdog_device *wdd)
231 struct watchdog_core_data *wd_data = wdd->wd_data;
232 unsigned long started_at;
235 if (watchdog_active(wdd))
238 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
240 started_at = jiffies;
241 if (watchdog_hw_running(wdd) && wdd->ops->ping)
242 err = wdd->ops->ping(wdd);
244 err = wdd->ops->start(wdd);
246 set_bit(WDOG_ACTIVE, &wdd->status);
247 wd_data->last_keepalive = started_at;
248 watchdog_update_worker(wdd);
255 * watchdog_stop: wrapper to stop the watchdog.
256 * @wdd: the watchdog device to stop
258 * The caller must hold wd_data->lock.
260 * Stop the watchdog if it is still active and unmark it active.
261 * This function returns zero on success or a negative errno code for
263 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
266 static int watchdog_stop(struct watchdog_device *wdd)
270 if (!watchdog_active(wdd))
273 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
274 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
279 if (wdd->ops->stop) {
280 clear_bit(WDOG_HW_RUNNING, &wdd->status);
281 err = wdd->ops->stop(wdd);
283 set_bit(WDOG_HW_RUNNING, &wdd->status);
287 clear_bit(WDOG_ACTIVE, &wdd->status);
288 watchdog_update_worker(wdd);
295 * watchdog_get_status: wrapper to get the watchdog status
296 * @wdd: the watchdog device to get the status from
298 * The caller must hold wd_data->lock.
300 * Get the watchdog's status flags.
303 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
305 struct watchdog_core_data *wd_data = wdd->wd_data;
308 if (wdd->ops->status)
309 status = wdd->ops->status(wdd);
311 status = wdd->bootstatus & (WDIOF_CARDRESET |
319 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
320 status |= WDIOF_MAGICCLOSE;
322 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
323 status |= WDIOF_KEEPALIVEPING;
329 * watchdog_set_timeout: set the watchdog timer timeout
330 * @wdd: the watchdog device to set the timeout for
331 * @timeout: timeout to set in seconds
333 * The caller must hold wd_data->lock.
336 static int watchdog_set_timeout(struct watchdog_device *wdd,
337 unsigned int timeout)
341 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
344 if (watchdog_timeout_invalid(wdd, timeout))
347 if (wdd->ops->set_timeout) {
348 err = wdd->ops->set_timeout(wdd, timeout);
350 wdd->timeout = timeout;
351 /* Disable pretimeout if it doesn't fit the new timeout */
352 if (wdd->pretimeout >= wdd->timeout)
356 watchdog_update_worker(wdd);
362 * watchdog_set_pretimeout: set the watchdog timer pretimeout
363 * @wdd: the watchdog device to set the timeout for
364 * @timeout: pretimeout to set in seconds
367 static int watchdog_set_pretimeout(struct watchdog_device *wdd,
368 unsigned int timeout)
372 if (!(wdd->info->options & WDIOF_PRETIMEOUT))
375 if (watchdog_pretimeout_invalid(wdd, timeout))
378 if (wdd->ops->set_pretimeout)
379 err = wdd->ops->set_pretimeout(wdd, timeout);
381 wdd->pretimeout = timeout;
387 * watchdog_get_timeleft: wrapper to get the time left before a reboot
388 * @wdd: the watchdog device to get the remaining time from
389 * @timeleft: the time that's left
391 * The caller must hold wd_data->lock.
393 * Get the time before a watchdog will reboot (if not pinged).
396 static int watchdog_get_timeleft(struct watchdog_device *wdd,
397 unsigned int *timeleft)
401 if (!wdd->ops->get_timeleft)
404 *timeleft = wdd->ops->get_timeleft(wdd);
409 #ifdef CONFIG_WATCHDOG_SYSFS
410 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
413 struct watchdog_device *wdd = dev_get_drvdata(dev);
415 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
417 static DEVICE_ATTR_RO(nowayout);
419 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
422 struct watchdog_device *wdd = dev_get_drvdata(dev);
423 struct watchdog_core_data *wd_data = wdd->wd_data;
426 mutex_lock(&wd_data->lock);
427 status = watchdog_get_status(wdd);
428 mutex_unlock(&wd_data->lock);
430 return sprintf(buf, "0x%x\n", status);
432 static DEVICE_ATTR_RO(status);
434 static ssize_t bootstatus_show(struct device *dev,
435 struct device_attribute *attr, char *buf)
437 struct watchdog_device *wdd = dev_get_drvdata(dev);
439 return sprintf(buf, "%u\n", wdd->bootstatus);
441 static DEVICE_ATTR_RO(bootstatus);
443 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
446 struct watchdog_device *wdd = dev_get_drvdata(dev);
447 struct watchdog_core_data *wd_data = wdd->wd_data;
451 mutex_lock(&wd_data->lock);
452 status = watchdog_get_timeleft(wdd, &val);
453 mutex_unlock(&wd_data->lock);
455 status = sprintf(buf, "%u\n", val);
459 static DEVICE_ATTR_RO(timeleft);
461 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
464 struct watchdog_device *wdd = dev_get_drvdata(dev);
466 return sprintf(buf, "%u\n", wdd->timeout);
468 static DEVICE_ATTR_RO(timeout);
470 static ssize_t pretimeout_show(struct device *dev,
471 struct device_attribute *attr, char *buf)
473 struct watchdog_device *wdd = dev_get_drvdata(dev);
475 return sprintf(buf, "%u\n", wdd->pretimeout);
477 static DEVICE_ATTR_RO(pretimeout);
479 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
482 struct watchdog_device *wdd = dev_get_drvdata(dev);
484 return sprintf(buf, "%s\n", wdd->info->identity);
486 static DEVICE_ATTR_RO(identity);
488 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
491 struct watchdog_device *wdd = dev_get_drvdata(dev);
493 if (watchdog_active(wdd))
494 return sprintf(buf, "active\n");
496 return sprintf(buf, "inactive\n");
498 static DEVICE_ATTR_RO(state);
500 static ssize_t pretimeout_available_governors_show(struct device *dev,
501 struct device_attribute *attr, char *buf)
503 return watchdog_pretimeout_available_governors_get(buf);
505 static DEVICE_ATTR_RO(pretimeout_available_governors);
507 static ssize_t pretimeout_governor_show(struct device *dev,
508 struct device_attribute *attr,
511 struct watchdog_device *wdd = dev_get_drvdata(dev);
513 return watchdog_pretimeout_governor_get(wdd, buf);
516 static ssize_t pretimeout_governor_store(struct device *dev,
517 struct device_attribute *attr,
518 const char *buf, size_t count)
520 struct watchdog_device *wdd = dev_get_drvdata(dev);
521 int ret = watchdog_pretimeout_governor_set(wdd, buf);
528 static DEVICE_ATTR_RW(pretimeout_governor);
530 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
533 struct device *dev = container_of(kobj, struct device, kobj);
534 struct watchdog_device *wdd = dev_get_drvdata(dev);
535 umode_t mode = attr->mode;
537 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
539 else if (attr == &dev_attr_pretimeout.attr &&
540 !(wdd->info->options & WDIOF_PRETIMEOUT))
542 else if ((attr == &dev_attr_pretimeout_governor.attr ||
543 attr == &dev_attr_pretimeout_available_governors.attr) &&
544 (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
545 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
550 static struct attribute *wdt_attrs[] = {
551 &dev_attr_state.attr,
552 &dev_attr_identity.attr,
553 &dev_attr_timeout.attr,
554 &dev_attr_pretimeout.attr,
555 &dev_attr_timeleft.attr,
556 &dev_attr_bootstatus.attr,
557 &dev_attr_status.attr,
558 &dev_attr_nowayout.attr,
559 &dev_attr_pretimeout_governor.attr,
560 &dev_attr_pretimeout_available_governors.attr,
564 static const struct attribute_group wdt_group = {
566 .is_visible = wdt_is_visible,
568 __ATTRIBUTE_GROUPS(wdt);
570 #define wdt_groups NULL
574 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
575 * @wdd: the watchdog device to do the ioctl on
576 * @cmd: watchdog command
577 * @arg: argument pointer
579 * The caller must hold wd_data->lock.
582 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
585 if (!wdd->ops->ioctl)
588 return wdd->ops->ioctl(wdd, cmd, arg);
592 * watchdog_write: writes to the watchdog.
593 * @file: file from VFS
594 * @data: user address of data
595 * @len: length of data
596 * @ppos: pointer to the file offset
598 * A write to a watchdog device is defined as a keepalive ping.
599 * Writing the magic 'V' sequence allows the next close to turn
600 * off the watchdog (if 'nowayout' is not set).
603 static ssize_t watchdog_write(struct file *file, const char __user *data,
604 size_t len, loff_t *ppos)
606 struct watchdog_core_data *wd_data = file->private_data;
607 struct watchdog_device *wdd;
616 * Note: just in case someone wrote the magic character
619 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
621 /* scan to see whether or not we got the magic character */
622 for (i = 0; i != len; i++) {
623 if (get_user(c, data + i))
626 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
629 /* someone wrote to us, so we send the watchdog a keepalive ping */
632 mutex_lock(&wd_data->lock);
635 err = watchdog_ping(wdd);
636 mutex_unlock(&wd_data->lock);
645 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
646 * @file: file handle to the device
647 * @cmd: watchdog command
648 * @arg: argument pointer
650 * The watchdog API defines a common set of functions for all watchdogs
651 * according to their available features.
654 static long watchdog_ioctl(struct file *file, unsigned int cmd,
657 struct watchdog_core_data *wd_data = file->private_data;
658 void __user *argp = (void __user *)arg;
659 struct watchdog_device *wdd;
660 int __user *p = argp;
664 mutex_lock(&wd_data->lock);
672 err = watchdog_ioctl_op(wdd, cmd, arg);
673 if (err != -ENOIOCTLCMD)
677 case WDIOC_GETSUPPORT:
678 err = copy_to_user(argp, wdd->info,
679 sizeof(struct watchdog_info)) ? -EFAULT : 0;
681 case WDIOC_GETSTATUS:
682 val = watchdog_get_status(wdd);
683 err = put_user(val, p);
685 case WDIOC_GETBOOTSTATUS:
686 err = put_user(wdd->bootstatus, p);
688 case WDIOC_SETOPTIONS:
689 if (get_user(val, p)) {
693 if (val & WDIOS_DISABLECARD) {
694 err = watchdog_stop(wdd);
698 if (val & WDIOS_ENABLECARD)
699 err = watchdog_start(wdd);
701 case WDIOC_KEEPALIVE:
702 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
706 err = watchdog_ping(wdd);
708 case WDIOC_SETTIMEOUT:
709 if (get_user(val, p)) {
713 err = watchdog_set_timeout(wdd, val);
716 /* If the watchdog is active then we send a keepalive ping
717 * to make sure that the watchdog keep's running (and if
718 * possible that it takes the new timeout) */
719 err = watchdog_ping(wdd);
723 case WDIOC_GETTIMEOUT:
724 /* timeout == 0 means that we don't know the timeout */
725 if (wdd->timeout == 0) {
729 err = put_user(wdd->timeout, p);
731 case WDIOC_GETTIMELEFT:
732 err = watchdog_get_timeleft(wdd, &val);
735 err = put_user(val, p);
737 case WDIOC_SETPRETIMEOUT:
738 if (get_user(val, p)) {
742 err = watchdog_set_pretimeout(wdd, val);
744 case WDIOC_GETPRETIMEOUT:
745 err = put_user(wdd->pretimeout, p);
753 mutex_unlock(&wd_data->lock);
758 * watchdog_open: open the /dev/watchdog* devices.
759 * @inode: inode of device
760 * @file: file handle to device
762 * When the /dev/watchdog* device gets opened, we start the watchdog.
763 * Watch out: the /dev/watchdog device is single open, so we make sure
764 * it can only be opened once.
767 static int watchdog_open(struct inode *inode, struct file *file)
769 struct watchdog_core_data *wd_data;
770 struct watchdog_device *wdd;
773 /* Get the corresponding watchdog device */
774 if (imajor(inode) == MISC_MAJOR)
775 wd_data = old_wd_data;
777 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
780 /* the watchdog is single open! */
781 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
787 * If the /dev/watchdog device is open, we don't want the module
790 if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
795 err = watchdog_start(wdd);
799 file->private_data = wd_data;
801 if (!watchdog_hw_running(wdd))
802 kref_get(&wd_data->kref);
804 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
805 return nonseekable_open(inode, file);
808 module_put(wd_data->wdd->ops->owner);
810 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
814 static void watchdog_core_data_release(struct kref *kref)
816 struct watchdog_core_data *wd_data;
818 wd_data = container_of(kref, struct watchdog_core_data, kref);
824 * watchdog_release: release the watchdog device.
825 * @inode: inode of device
826 * @file: file handle to device
828 * This is the code for when /dev/watchdog gets closed. We will only
829 * stop the watchdog when we have received the magic char (and nowayout
830 * was not set), else the watchdog will keep running.
833 static int watchdog_release(struct inode *inode, struct file *file)
835 struct watchdog_core_data *wd_data = file->private_data;
836 struct watchdog_device *wdd;
840 mutex_lock(&wd_data->lock);
847 * We only stop the watchdog if we received the magic character
848 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
849 * watchdog_stop will fail.
851 if (!test_bit(WDOG_ACTIVE, &wdd->status))
853 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
854 !(wdd->info->options & WDIOF_MAGICCLOSE))
855 err = watchdog_stop(wdd);
857 /* If the watchdog was not stopped, send a keepalive ping */
859 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
863 watchdog_update_worker(wdd);
865 /* make sure that /dev/watchdog can be re-opened */
866 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
869 running = wdd && watchdog_hw_running(wdd);
870 mutex_unlock(&wd_data->lock);
872 * Allow the owner module to be unloaded again unless the watchdog
873 * is still running. If the watchdog is still running, it can not
874 * be stopped, and its driver must not be unloaded.
877 module_put(wd_data->cdev.owner);
878 kref_put(&wd_data->kref, watchdog_core_data_release);
883 static const struct file_operations watchdog_fops = {
884 .owner = THIS_MODULE,
885 .write = watchdog_write,
886 .unlocked_ioctl = watchdog_ioctl,
887 .open = watchdog_open,
888 .release = watchdog_release,
891 static struct miscdevice watchdog_miscdev = {
892 .minor = WATCHDOG_MINOR,
894 .fops = &watchdog_fops,
898 * watchdog_cdev_register: register watchdog character device
899 * @wdd: watchdog device
900 * @devno: character device number
902 * Register a watchdog character device including handling the legacy
903 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
904 * thus we set it up like that.
907 static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
909 struct watchdog_core_data *wd_data;
912 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
915 kref_init(&wd_data->kref);
916 mutex_init(&wd_data->lock);
919 wdd->wd_data = wd_data;
924 INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
927 old_wd_data = wd_data;
928 watchdog_miscdev.parent = wdd->parent;
929 err = misc_register(&watchdog_miscdev);
931 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
932 wdd->info->identity, WATCHDOG_MINOR, err);
934 pr_err("%s: a legacy watchdog module is probably present.\n",
935 wdd->info->identity);
942 /* Fill in the data structures */
943 cdev_init(&wd_data->cdev, &watchdog_fops);
944 wd_data->cdev.owner = wdd->ops->owner;
947 err = cdev_add(&wd_data->cdev, devno, 1);
949 pr_err("watchdog%d unable to add device %d:%d\n",
950 wdd->id, MAJOR(watchdog_devt), wdd->id);
952 misc_deregister(&watchdog_miscdev);
954 kref_put(&wd_data->kref, watchdog_core_data_release);
959 /* Record time of most recent heartbeat as 'just before now'. */
960 wd_data->last_hw_keepalive = jiffies - 1;
963 * If the watchdog is running, prevent its driver from being unloaded,
964 * and schedule an immediate ping.
966 if (watchdog_hw_running(wdd)) {
967 if (handle_boot_enabled) {
968 __module_get(wdd->ops->owner);
969 kref_get(&wd_data->kref);
970 queue_delayed_work(watchdog_wq, &wd_data->work, 0);
972 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
981 * watchdog_cdev_unregister: unregister watchdog character device
982 * @watchdog: watchdog device
984 * Unregister watchdog character device and if needed the legacy
985 * /dev/watchdog device.
988 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
990 struct watchdog_core_data *wd_data = wdd->wd_data;
992 cdev_del(&wd_data->cdev);
994 misc_deregister(&watchdog_miscdev);
998 mutex_lock(&wd_data->lock);
1000 wdd->wd_data = NULL;
1001 mutex_unlock(&wd_data->lock);
1003 if (watchdog_active(wdd) &&
1004 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
1008 cancel_delayed_work_sync(&wd_data->work);
1010 kref_put(&wd_data->kref, watchdog_core_data_release);
1013 static struct class watchdog_class = {
1015 .owner = THIS_MODULE,
1016 .dev_groups = wdt_groups,
1020 * watchdog_dev_register: register a watchdog device
1021 * @wdd: watchdog device
1023 * Register a watchdog device including handling the legacy
1024 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1025 * thus we set it up like that.
1028 int watchdog_dev_register(struct watchdog_device *wdd)
1034 devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
1036 ret = watchdog_cdev_register(wdd, devno);
1040 dev = device_create_with_groups(&watchdog_class, wdd->parent,
1041 devno, wdd, wdd->groups,
1042 "watchdog%d", wdd->id);
1044 watchdog_cdev_unregister(wdd);
1045 return PTR_ERR(dev);
1048 ret = watchdog_register_pretimeout(wdd);
1050 device_destroy(&watchdog_class, devno);
1051 watchdog_cdev_unregister(wdd);
1058 * watchdog_dev_unregister: unregister a watchdog device
1059 * @watchdog: watchdog device
1061 * Unregister watchdog device and if needed the legacy
1062 * /dev/watchdog device.
1065 void watchdog_dev_unregister(struct watchdog_device *wdd)
1067 watchdog_unregister_pretimeout(wdd);
1068 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
1069 watchdog_cdev_unregister(wdd);
1073 * watchdog_dev_init: init dev part of watchdog core
1075 * Allocate a range of chardev nodes to use for watchdog devices
1078 int __init watchdog_dev_init(void)
1082 watchdog_wq = alloc_workqueue("watchdogd",
1083 WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
1085 pr_err("Failed to create watchdog workqueue\n");
1089 err = class_register(&watchdog_class);
1091 pr_err("couldn't register class\n");
1095 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1097 pr_err("watchdog: unable to allocate char dev region\n");
1104 class_unregister(&watchdog_class);
1106 destroy_workqueue(watchdog_wq);
1111 * watchdog_dev_exit: exit dev part of watchdog core
1113 * Release the range of chardev nodes used for watchdog devices
1116 void __exit watchdog_dev_exit(void)
1118 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1119 class_unregister(&watchdog_class);
1120 destroy_workqueue(watchdog_wq);
1123 module_param(handle_boot_enabled, bool, 0444);
1124 MODULE_PARM_DESC(handle_boot_enabled,
1125 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1126 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");