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",
271 err
= wdd
->ops
->stop(wdd
);
273 set_bit(WDOG_HW_RUNNING
, &wdd
->status
);
276 clear_bit(WDOG_ACTIVE
, &wdd
->status
);
277 watchdog_update_worker(wdd
);
284 * watchdog_get_status: wrapper to get the watchdog status
285 * @wdd: the watchdog device to get the status from
287 * The caller must hold wd_data->lock.
289 * Get the watchdog's status flags.
292 static unsigned int watchdog_get_status(struct watchdog_device
*wdd
)
294 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
297 if (wdd
->ops
->status
)
298 status
= wdd
->ops
->status(wdd
);
300 status
= wdd
->bootstatus
& (WDIOF_CARDRESET
|
308 if (test_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
))
309 status
|= WDIOF_MAGICCLOSE
;
311 if (test_and_clear_bit(_WDOG_KEEPALIVE
, &wd_data
->status
))
312 status
|= WDIOF_KEEPALIVEPING
;
318 * watchdog_set_timeout: set the watchdog timer timeout
319 * @wdd: the watchdog device to set the timeout for
320 * @timeout: timeout to set in seconds
322 * The caller must hold wd_data->lock.
325 static int watchdog_set_timeout(struct watchdog_device
*wdd
,
326 unsigned int timeout
)
330 if (!(wdd
->info
->options
& WDIOF_SETTIMEOUT
))
333 if (watchdog_timeout_invalid(wdd
, timeout
))
336 if (wdd
->ops
->set_timeout
)
337 err
= wdd
->ops
->set_timeout(wdd
, timeout
);
339 wdd
->timeout
= timeout
;
341 watchdog_update_worker(wdd
);
347 * watchdog_get_timeleft: wrapper to get the time left before a reboot
348 * @wdd: the watchdog device to get the remaining time from
349 * @timeleft: the time that's left
351 * The caller must hold wd_data->lock.
353 * Get the time before a watchdog will reboot (if not pinged).
356 static int watchdog_get_timeleft(struct watchdog_device
*wdd
,
357 unsigned int *timeleft
)
361 if (!wdd
->ops
->get_timeleft
)
364 *timeleft
= wdd
->ops
->get_timeleft(wdd
);
369 #ifdef CONFIG_WATCHDOG_SYSFS
370 static ssize_t
nowayout_show(struct device
*dev
, struct device_attribute
*attr
,
373 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
375 return sprintf(buf
, "%d\n", !!test_bit(WDOG_NO_WAY_OUT
, &wdd
->status
));
377 static DEVICE_ATTR_RO(nowayout
);
379 static ssize_t
status_show(struct device
*dev
, struct device_attribute
*attr
,
382 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
383 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
386 mutex_lock(&wd_data
->lock
);
387 status
= watchdog_get_status(wdd
);
388 mutex_unlock(&wd_data
->lock
);
390 return sprintf(buf
, "0x%x\n", status
);
392 static DEVICE_ATTR_RO(status
);
394 static ssize_t
bootstatus_show(struct device
*dev
,
395 struct device_attribute
*attr
, char *buf
)
397 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
399 return sprintf(buf
, "%u\n", wdd
->bootstatus
);
401 static DEVICE_ATTR_RO(bootstatus
);
403 static ssize_t
timeleft_show(struct device
*dev
, struct device_attribute
*attr
,
406 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
407 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
411 mutex_lock(&wd_data
->lock
);
412 status
= watchdog_get_timeleft(wdd
, &val
);
413 mutex_unlock(&wd_data
->lock
);
415 status
= sprintf(buf
, "%u\n", val
);
419 static DEVICE_ATTR_RO(timeleft
);
421 static ssize_t
timeout_show(struct device
*dev
, struct device_attribute
*attr
,
424 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
426 return sprintf(buf
, "%u\n", wdd
->timeout
);
428 static DEVICE_ATTR_RO(timeout
);
430 static ssize_t
identity_show(struct device
*dev
, struct device_attribute
*attr
,
433 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
435 return sprintf(buf
, "%s\n", wdd
->info
->identity
);
437 static DEVICE_ATTR_RO(identity
);
439 static ssize_t
state_show(struct device
*dev
, struct device_attribute
*attr
,
442 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
444 if (watchdog_active(wdd
))
445 return sprintf(buf
, "active\n");
447 return sprintf(buf
, "inactive\n");
449 static DEVICE_ATTR_RO(state
);
451 static umode_t
wdt_is_visible(struct kobject
*kobj
, struct attribute
*attr
,
454 struct device
*dev
= container_of(kobj
, struct device
, kobj
);
455 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
456 umode_t mode
= attr
->mode
;
458 if (attr
== &dev_attr_timeleft
.attr
&& !wdd
->ops
->get_timeleft
)
463 static struct attribute
*wdt_attrs
[] = {
464 &dev_attr_state
.attr
,
465 &dev_attr_identity
.attr
,
466 &dev_attr_timeout
.attr
,
467 &dev_attr_timeleft
.attr
,
468 &dev_attr_bootstatus
.attr
,
469 &dev_attr_status
.attr
,
470 &dev_attr_nowayout
.attr
,
474 static const struct attribute_group wdt_group
= {
476 .is_visible
= wdt_is_visible
,
478 __ATTRIBUTE_GROUPS(wdt
);
480 #define wdt_groups NULL
484 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
485 * @wdd: the watchdog device to do the ioctl on
486 * @cmd: watchdog command
487 * @arg: argument pointer
489 * The caller must hold wd_data->lock.
492 static int watchdog_ioctl_op(struct watchdog_device
*wdd
, unsigned int cmd
,
495 if (!wdd
->ops
->ioctl
)
498 return wdd
->ops
->ioctl(wdd
, cmd
, arg
);
502 * watchdog_write: writes to the watchdog.
503 * @file: file from VFS
504 * @data: user address of data
505 * @len: length of data
506 * @ppos: pointer to the file offset
508 * A write to a watchdog device is defined as a keepalive ping.
509 * Writing the magic 'V' sequence allows the next close to turn
510 * off the watchdog (if 'nowayout' is not set).
513 static ssize_t
watchdog_write(struct file
*file
, const char __user
*data
,
514 size_t len
, loff_t
*ppos
)
516 struct watchdog_core_data
*wd_data
= file
->private_data
;
517 struct watchdog_device
*wdd
;
526 * Note: just in case someone wrote the magic character
529 clear_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
);
531 /* scan to see whether or not we got the magic character */
532 for (i
= 0; i
!= len
; i
++) {
533 if (get_user(c
, data
+ i
))
536 set_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
);
539 /* someone wrote to us, so we send the watchdog a keepalive ping */
542 mutex_lock(&wd_data
->lock
);
545 err
= watchdog_ping(wdd
);
546 mutex_unlock(&wd_data
->lock
);
555 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
556 * @file: file handle to the device
557 * @cmd: watchdog command
558 * @arg: argument pointer
560 * The watchdog API defines a common set of functions for all watchdogs
561 * according to their available features.
564 static long watchdog_ioctl(struct file
*file
, unsigned int cmd
,
567 struct watchdog_core_data
*wd_data
= file
->private_data
;
568 void __user
*argp
= (void __user
*)arg
;
569 struct watchdog_device
*wdd
;
570 int __user
*p
= argp
;
574 mutex_lock(&wd_data
->lock
);
582 err
= watchdog_ioctl_op(wdd
, cmd
, arg
);
583 if (err
!= -ENOIOCTLCMD
)
587 case WDIOC_GETSUPPORT
:
588 err
= copy_to_user(argp
, wdd
->info
,
589 sizeof(struct watchdog_info
)) ? -EFAULT
: 0;
591 case WDIOC_GETSTATUS
:
592 val
= watchdog_get_status(wdd
);
593 err
= put_user(val
, p
);
595 case WDIOC_GETBOOTSTATUS
:
596 err
= put_user(wdd
->bootstatus
, p
);
598 case WDIOC_SETOPTIONS
:
599 if (get_user(val
, p
)) {
603 if (val
& WDIOS_DISABLECARD
) {
604 err
= watchdog_stop(wdd
);
608 if (val
& WDIOS_ENABLECARD
)
609 err
= watchdog_start(wdd
);
611 case WDIOC_KEEPALIVE
:
612 if (!(wdd
->info
->options
& WDIOF_KEEPALIVEPING
)) {
616 err
= watchdog_ping(wdd
);
618 case WDIOC_SETTIMEOUT
:
619 if (get_user(val
, p
)) {
623 err
= watchdog_set_timeout(wdd
, val
);
626 /* If the watchdog is active then we send a keepalive ping
627 * to make sure that the watchdog keep's running (and if
628 * possible that it takes the new timeout) */
629 err
= watchdog_ping(wdd
);
633 case WDIOC_GETTIMEOUT
:
634 /* timeout == 0 means that we don't know the timeout */
635 if (wdd
->timeout
== 0) {
639 err
= put_user(wdd
->timeout
, p
);
641 case WDIOC_GETTIMELEFT
:
642 err
= watchdog_get_timeleft(wdd
, &val
);
645 err
= put_user(val
, p
);
653 mutex_unlock(&wd_data
->lock
);
658 * watchdog_open: open the /dev/watchdog* devices.
659 * @inode: inode of device
660 * @file: file handle to device
662 * When the /dev/watchdog* device gets opened, we start the watchdog.
663 * Watch out: the /dev/watchdog device is single open, so we make sure
664 * it can only be opened once.
667 static int watchdog_open(struct inode
*inode
, struct file
*file
)
669 struct watchdog_core_data
*wd_data
;
670 struct watchdog_device
*wdd
;
673 /* Get the corresponding watchdog device */
674 if (imajor(inode
) == MISC_MAJOR
)
675 wd_data
= old_wd_data
;
677 wd_data
= container_of(inode
->i_cdev
, struct watchdog_core_data
,
680 /* the watchdog is single open! */
681 if (test_and_set_bit(_WDOG_DEV_OPEN
, &wd_data
->status
))
687 * If the /dev/watchdog device is open, we don't want the module
690 if (!watchdog_hw_running(wdd
) && !try_module_get(wdd
->ops
->owner
)) {
695 err
= watchdog_start(wdd
);
699 file
->private_data
= wd_data
;
701 if (!watchdog_hw_running(wdd
))
702 kref_get(&wd_data
->kref
);
704 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
705 return nonseekable_open(inode
, file
);
708 module_put(wd_data
->wdd
->ops
->owner
);
710 clear_bit(_WDOG_DEV_OPEN
, &wd_data
->status
);
714 static void watchdog_core_data_release(struct kref
*kref
)
716 struct watchdog_core_data
*wd_data
;
718 wd_data
= container_of(kref
, struct watchdog_core_data
, kref
);
724 * watchdog_release: release the watchdog device.
725 * @inode: inode of device
726 * @file: file handle to device
728 * This is the code for when /dev/watchdog gets closed. We will only
729 * stop the watchdog when we have received the magic char (and nowayout
730 * was not set), else the watchdog will keep running.
733 static int watchdog_release(struct inode
*inode
, struct file
*file
)
735 struct watchdog_core_data
*wd_data
= file
->private_data
;
736 struct watchdog_device
*wdd
;
740 mutex_lock(&wd_data
->lock
);
747 * We only stop the watchdog if we received the magic character
748 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
749 * watchdog_stop will fail.
751 if (!test_bit(WDOG_ACTIVE
, &wdd
->status
))
753 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
) ||
754 !(wdd
->info
->options
& WDIOF_MAGICCLOSE
))
755 err
= watchdog_stop(wdd
);
757 /* If the watchdog was not stopped, send a keepalive ping */
759 pr_crit("watchdog%d: watchdog did not stop!\n", wdd
->id
);
763 watchdog_update_worker(wdd
);
765 /* make sure that /dev/watchdog can be re-opened */
766 clear_bit(_WDOG_DEV_OPEN
, &wd_data
->status
);
769 running
= wdd
&& watchdog_hw_running(wdd
);
770 mutex_unlock(&wd_data
->lock
);
772 * Allow the owner module to be unloaded again unless the watchdog
773 * is still running. If the watchdog is still running, it can not
774 * be stopped, and its driver must not be unloaded.
777 module_put(wd_data
->cdev
.owner
);
778 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
783 static const struct file_operations watchdog_fops
= {
784 .owner
= THIS_MODULE
,
785 .write
= watchdog_write
,
786 .unlocked_ioctl
= watchdog_ioctl
,
787 .open
= watchdog_open
,
788 .release
= watchdog_release
,
791 static struct miscdevice watchdog_miscdev
= {
792 .minor
= WATCHDOG_MINOR
,
794 .fops
= &watchdog_fops
,
798 * watchdog_cdev_register: register watchdog character device
799 * @wdd: watchdog device
800 * @devno: character device number
802 * Register a watchdog character device including handling the legacy
803 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
804 * thus we set it up like that.
807 static int watchdog_cdev_register(struct watchdog_device
*wdd
, dev_t devno
)
809 struct watchdog_core_data
*wd_data
;
812 wd_data
= kzalloc(sizeof(struct watchdog_core_data
), GFP_KERNEL
);
815 kref_init(&wd_data
->kref
);
816 mutex_init(&wd_data
->lock
);
819 wdd
->wd_data
= wd_data
;
824 INIT_DELAYED_WORK(&wd_data
->work
, watchdog_ping_work
);
827 old_wd_data
= wd_data
;
828 watchdog_miscdev
.parent
= wdd
->parent
;
829 err
= misc_register(&watchdog_miscdev
);
831 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
832 wdd
->info
->identity
, WATCHDOG_MINOR
, err
);
834 pr_err("%s: a legacy watchdog module is probably present.\n",
835 wdd
->info
->identity
);
842 /* Fill in the data structures */
843 cdev_init(&wd_data
->cdev
, &watchdog_fops
);
844 wd_data
->cdev
.owner
= wdd
->ops
->owner
;
847 err
= cdev_add(&wd_data
->cdev
, devno
, 1);
849 pr_err("watchdog%d unable to add device %d:%d\n",
850 wdd
->id
, MAJOR(watchdog_devt
), wdd
->id
);
852 misc_deregister(&watchdog_miscdev
);
854 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
859 /* Record time of most recent heartbeat as 'just before now'. */
860 wd_data
->last_hw_keepalive
= jiffies
- 1;
863 * If the watchdog is running, prevent its driver from being unloaded,
864 * and schedule an immediate ping.
866 if (watchdog_hw_running(wdd
)) {
867 __module_get(wdd
->ops
->owner
);
868 kref_get(&wd_data
->kref
);
869 queue_delayed_work(watchdog_wq
, &wd_data
->work
, 0);
876 * watchdog_cdev_unregister: unregister watchdog character device
877 * @watchdog: watchdog device
879 * Unregister watchdog character device and if needed the legacy
880 * /dev/watchdog device.
883 static void watchdog_cdev_unregister(struct watchdog_device
*wdd
)
885 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
887 cdev_del(&wd_data
->cdev
);
889 misc_deregister(&watchdog_miscdev
);
893 mutex_lock(&wd_data
->lock
);
896 mutex_unlock(&wd_data
->lock
);
898 cancel_delayed_work_sync(&wd_data
->work
);
900 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
903 static struct class watchdog_class
= {
905 .owner
= THIS_MODULE
,
906 .dev_groups
= wdt_groups
,
910 * watchdog_dev_register: register a watchdog device
911 * @wdd: watchdog device
913 * Register a watchdog device including handling the legacy
914 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
915 * thus we set it up like that.
918 int watchdog_dev_register(struct watchdog_device
*wdd
)
924 devno
= MKDEV(MAJOR(watchdog_devt
), wdd
->id
);
926 ret
= watchdog_cdev_register(wdd
, devno
);
930 dev
= device_create_with_groups(&watchdog_class
, wdd
->parent
,
931 devno
, wdd
, wdd
->groups
,
932 "watchdog%d", wdd
->id
);
934 watchdog_cdev_unregister(wdd
);
942 * watchdog_dev_unregister: unregister a watchdog device
943 * @watchdog: watchdog device
945 * Unregister watchdog device and if needed the legacy
946 * /dev/watchdog device.
949 void watchdog_dev_unregister(struct watchdog_device
*wdd
)
951 device_destroy(&watchdog_class
, wdd
->wd_data
->cdev
.dev
);
952 watchdog_cdev_unregister(wdd
);
956 * watchdog_dev_init: init dev part of watchdog core
958 * Allocate a range of chardev nodes to use for watchdog devices
961 int __init
watchdog_dev_init(void)
965 watchdog_wq
= alloc_workqueue("watchdogd",
966 WQ_HIGHPRI
| WQ_MEM_RECLAIM
, 0);
968 pr_err("Failed to create watchdog workqueue\n");
972 err
= class_register(&watchdog_class
);
974 pr_err("couldn't register class\n");
978 err
= alloc_chrdev_region(&watchdog_devt
, 0, MAX_DOGS
, "watchdog");
980 pr_err("watchdog: unable to allocate char dev region\n");
987 class_unregister(&watchdog_class
);
989 destroy_workqueue(watchdog_wq
);
994 * watchdog_dev_exit: exit dev part of watchdog core
996 * Release the range of chardev nodes used for watchdog devices
999 void __exit
watchdog_dev_exit(void)
1001 unregister_chrdev_region(watchdog_devt
, MAX_DOGS
);
1002 class_unregister(&watchdog_class
);
1003 destroy_workqueue(watchdog_wq
);