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/kernel.h> /* For printk/panic/... */
40 #include <linux/kref.h> /* For data references */
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/uaccess.h> /* For copy_to_user/put_user/... */
49 #include "watchdog_core.h"
52 * struct watchdog_core_data - watchdog core internal data
53 * @kref: Reference count.
54 * @cdev: The watchdog's Character device.
55 * @wdd: Pointer to watchdog device.
56 * @lock: Lock for watchdog core.
57 * @status: Watchdog core internal status bits.
59 struct watchdog_core_data
{
62 struct watchdog_device
*wdd
;
64 unsigned long status
; /* Internal status bits */
65 #define _WDOG_DEV_OPEN 0 /* Opened ? */
66 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
69 /* the dev_t structure to store the dynamically allocated watchdog devices */
70 static dev_t watchdog_devt
;
71 /* Reference to watchdog device behind /dev/watchdog */
72 static struct watchdog_core_data
*old_wd_data
;
75 * watchdog_ping: ping the watchdog.
76 * @wdd: the watchdog device to ping
78 * The caller must hold wd_data->lock.
80 * If the watchdog has no own ping operation then it needs to be
81 * restarted via the start operation. This wrapper function does
83 * We only ping when the watchdog device is running.
86 static int watchdog_ping(struct watchdog_device
*wdd
)
90 if (!watchdog_active(wdd
))
94 err
= wdd
->ops
->ping(wdd
); /* ping the watchdog */
96 err
= wdd
->ops
->start(wdd
); /* restart watchdog */
102 * watchdog_start: wrapper to start the watchdog.
103 * @wdd: the watchdog device to start
105 * The caller must hold wd_data->lock.
107 * Start the watchdog if it is not active and mark it active.
108 * This function returns zero on success or a negative errno code for
112 static int watchdog_start(struct watchdog_device
*wdd
)
116 if (watchdog_active(wdd
))
119 err
= wdd
->ops
->start(wdd
);
121 set_bit(WDOG_ACTIVE
, &wdd
->status
);
127 * watchdog_stop: wrapper to stop the watchdog.
128 * @wdd: the watchdog device to stop
130 * The caller must hold wd_data->lock.
132 * Stop the watchdog if it is still active and unmark it active.
133 * This function returns zero on success or a negative errno code for
135 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
138 static int watchdog_stop(struct watchdog_device
*wdd
)
142 if (!watchdog_active(wdd
))
145 if (test_bit(WDOG_NO_WAY_OUT
, &wdd
->status
)) {
146 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
151 err
= wdd
->ops
->stop(wdd
);
153 clear_bit(WDOG_ACTIVE
, &wdd
->status
);
159 * watchdog_get_status: wrapper to get the watchdog status
160 * @wdd: the watchdog device to get the status from
162 * The caller must hold wd_data->lock.
164 * Get the watchdog's status flags.
167 static unsigned int watchdog_get_status(struct watchdog_device
*wdd
)
169 if (!wdd
->ops
->status
)
172 return wdd
->ops
->status(wdd
);
176 * watchdog_set_timeout: set the watchdog timer timeout
177 * @wdd: the watchdog device to set the timeout for
178 * @timeout: timeout to set in seconds
180 * The caller must hold wd_data->lock.
183 static int watchdog_set_timeout(struct watchdog_device
*wdd
,
184 unsigned int timeout
)
186 if (!wdd
->ops
->set_timeout
|| !(wdd
->info
->options
& WDIOF_SETTIMEOUT
))
189 if (watchdog_timeout_invalid(wdd
, timeout
))
192 return wdd
->ops
->set_timeout(wdd
, timeout
);
196 * watchdog_get_timeleft: wrapper to get the time left before a reboot
197 * @wdd: the watchdog device to get the remaining time from
198 * @timeleft: the time that's left
200 * The caller must hold wd_data->lock.
202 * Get the time before a watchdog will reboot (if not pinged).
205 static int watchdog_get_timeleft(struct watchdog_device
*wdd
,
206 unsigned int *timeleft
)
210 if (!wdd
->ops
->get_timeleft
)
213 *timeleft
= wdd
->ops
->get_timeleft(wdd
);
218 #ifdef CONFIG_WATCHDOG_SYSFS
219 static ssize_t
nowayout_show(struct device
*dev
, struct device_attribute
*attr
,
222 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
224 return sprintf(buf
, "%d\n", !!test_bit(WDOG_NO_WAY_OUT
, &wdd
->status
));
226 static DEVICE_ATTR_RO(nowayout
);
228 static ssize_t
status_show(struct device
*dev
, struct device_attribute
*attr
,
231 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
232 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
235 mutex_lock(&wd_data
->lock
);
236 status
= watchdog_get_status(wdd
);
237 mutex_unlock(&wd_data
->lock
);
239 return sprintf(buf
, "%u\n", status
);
241 static DEVICE_ATTR_RO(status
);
243 static ssize_t
bootstatus_show(struct device
*dev
,
244 struct device_attribute
*attr
, char *buf
)
246 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
248 return sprintf(buf
, "%u\n", wdd
->bootstatus
);
250 static DEVICE_ATTR_RO(bootstatus
);
252 static ssize_t
timeleft_show(struct device
*dev
, struct device_attribute
*attr
,
255 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
256 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
260 mutex_lock(&wd_data
->lock
);
261 status
= watchdog_get_timeleft(wdd
, &val
);
262 mutex_unlock(&wd_data
->lock
);
264 status
= sprintf(buf
, "%u\n", val
);
268 static DEVICE_ATTR_RO(timeleft
);
270 static ssize_t
timeout_show(struct device
*dev
, struct device_attribute
*attr
,
273 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
275 return sprintf(buf
, "%u\n", wdd
->timeout
);
277 static DEVICE_ATTR_RO(timeout
);
279 static ssize_t
identity_show(struct device
*dev
, struct device_attribute
*attr
,
282 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
284 return sprintf(buf
, "%s\n", wdd
->info
->identity
);
286 static DEVICE_ATTR_RO(identity
);
288 static ssize_t
state_show(struct device
*dev
, struct device_attribute
*attr
,
291 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
293 if (watchdog_active(wdd
))
294 return sprintf(buf
, "active\n");
296 return sprintf(buf
, "inactive\n");
298 static DEVICE_ATTR_RO(state
);
300 static umode_t
wdt_is_visible(struct kobject
*kobj
, struct attribute
*attr
,
303 struct device
*dev
= container_of(kobj
, struct device
, kobj
);
304 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
305 umode_t mode
= attr
->mode
;
307 if (attr
== &dev_attr_status
.attr
&& !wdd
->ops
->status
)
309 else if (attr
== &dev_attr_timeleft
.attr
&& !wdd
->ops
->get_timeleft
)
314 static struct attribute
*wdt_attrs
[] = {
315 &dev_attr_state
.attr
,
316 &dev_attr_identity
.attr
,
317 &dev_attr_timeout
.attr
,
318 &dev_attr_timeleft
.attr
,
319 &dev_attr_bootstatus
.attr
,
320 &dev_attr_status
.attr
,
321 &dev_attr_nowayout
.attr
,
325 static const struct attribute_group wdt_group
= {
327 .is_visible
= wdt_is_visible
,
329 __ATTRIBUTE_GROUPS(wdt
);
331 #define wdt_groups NULL
335 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
336 * @wdd: the watchdog device to do the ioctl on
337 * @cmd: watchdog command
338 * @arg: argument pointer
340 * The caller must hold wd_data->lock.
343 static int watchdog_ioctl_op(struct watchdog_device
*wdd
, unsigned int cmd
,
346 if (!wdd
->ops
->ioctl
)
349 return wdd
->ops
->ioctl(wdd
, cmd
, arg
);
353 * watchdog_write: writes to the watchdog.
354 * @file: file from VFS
355 * @data: user address of data
356 * @len: length of data
357 * @ppos: pointer to the file offset
359 * A write to a watchdog device is defined as a keepalive ping.
360 * Writing the magic 'V' sequence allows the next close to turn
361 * off the watchdog (if 'nowayout' is not set).
364 static ssize_t
watchdog_write(struct file
*file
, const char __user
*data
,
365 size_t len
, loff_t
*ppos
)
367 struct watchdog_core_data
*wd_data
= file
->private_data
;
368 struct watchdog_device
*wdd
;
377 * Note: just in case someone wrote the magic character
380 clear_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
);
382 /* scan to see whether or not we got the magic character */
383 for (i
= 0; i
!= len
; i
++) {
384 if (get_user(c
, data
+ i
))
387 set_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
);
390 /* someone wrote to us, so we send the watchdog a keepalive ping */
393 mutex_lock(&wd_data
->lock
);
396 err
= watchdog_ping(wdd
);
397 mutex_unlock(&wd_data
->lock
);
406 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
407 * @file: file handle to the device
408 * @cmd: watchdog command
409 * @arg: argument pointer
411 * The watchdog API defines a common set of functions for all watchdogs
412 * according to their available features.
415 static long watchdog_ioctl(struct file
*file
, unsigned int cmd
,
418 struct watchdog_core_data
*wd_data
= file
->private_data
;
419 void __user
*argp
= (void __user
*)arg
;
420 struct watchdog_device
*wdd
;
421 int __user
*p
= argp
;
425 mutex_lock(&wd_data
->lock
);
433 err
= watchdog_ioctl_op(wdd
, cmd
, arg
);
434 if (err
!= -ENOIOCTLCMD
)
438 case WDIOC_GETSUPPORT
:
439 err
= copy_to_user(argp
, wdd
->info
,
440 sizeof(struct watchdog_info
)) ? -EFAULT
: 0;
442 case WDIOC_GETSTATUS
:
443 val
= watchdog_get_status(wdd
);
444 err
= put_user(val
, p
);
446 case WDIOC_GETBOOTSTATUS
:
447 err
= put_user(wdd
->bootstatus
, p
);
449 case WDIOC_SETOPTIONS
:
450 if (get_user(val
, p
)) {
454 if (val
& WDIOS_DISABLECARD
) {
455 err
= watchdog_stop(wdd
);
459 if (val
& WDIOS_ENABLECARD
)
460 err
= watchdog_start(wdd
);
462 case WDIOC_KEEPALIVE
:
463 if (!(wdd
->info
->options
& WDIOF_KEEPALIVEPING
)) {
467 err
= watchdog_ping(wdd
);
469 case WDIOC_SETTIMEOUT
:
470 if (get_user(val
, p
)) {
474 err
= watchdog_set_timeout(wdd
, val
);
477 /* If the watchdog is active then we send a keepalive ping
478 * to make sure that the watchdog keep's running (and if
479 * possible that it takes the new timeout) */
480 err
= watchdog_ping(wdd
);
484 case WDIOC_GETTIMEOUT
:
485 /* timeout == 0 means that we don't know the timeout */
486 if (wdd
->timeout
== 0) {
490 err
= put_user(wdd
->timeout
, p
);
492 case WDIOC_GETTIMELEFT
:
493 err
= watchdog_get_timeleft(wdd
, &val
);
496 err
= put_user(val
, p
);
504 mutex_unlock(&wd_data
->lock
);
509 * watchdog_open: open the /dev/watchdog* devices.
510 * @inode: inode of device
511 * @file: file handle to device
513 * When the /dev/watchdog* device gets opened, we start the watchdog.
514 * Watch out: the /dev/watchdog device is single open, so we make sure
515 * it can only be opened once.
518 static int watchdog_open(struct inode
*inode
, struct file
*file
)
520 struct watchdog_core_data
*wd_data
;
521 struct watchdog_device
*wdd
;
524 /* Get the corresponding watchdog device */
525 if (imajor(inode
) == MISC_MAJOR
)
526 wd_data
= old_wd_data
;
528 wd_data
= container_of(inode
->i_cdev
, struct watchdog_core_data
,
531 /* the watchdog is single open! */
532 if (test_and_set_bit(_WDOG_DEV_OPEN
, &wd_data
->status
))
538 * If the /dev/watchdog device is open, we don't want the module
541 if (!try_module_get(wdd
->ops
->owner
)) {
546 err
= watchdog_start(wdd
);
550 file
->private_data
= wd_data
;
552 kref_get(&wd_data
->kref
);
554 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
555 return nonseekable_open(inode
, file
);
558 module_put(wd_data
->wdd
->ops
->owner
);
560 clear_bit(_WDOG_DEV_OPEN
, &wd_data
->status
);
564 static void watchdog_core_data_release(struct kref
*kref
)
566 struct watchdog_core_data
*wd_data
;
568 wd_data
= container_of(kref
, struct watchdog_core_data
, kref
);
574 * watchdog_release: release the watchdog device.
575 * @inode: inode of device
576 * @file: file handle to device
578 * This is the code for when /dev/watchdog gets closed. We will only
579 * stop the watchdog when we have received the magic char (and nowayout
580 * was not set), else the watchdog will keep running.
583 static int watchdog_release(struct inode
*inode
, struct file
*file
)
585 struct watchdog_core_data
*wd_data
= file
->private_data
;
586 struct watchdog_device
*wdd
;
589 mutex_lock(&wd_data
->lock
);
596 * We only stop the watchdog if we received the magic character
597 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
598 * watchdog_stop will fail.
600 if (!test_bit(WDOG_ACTIVE
, &wdd
->status
))
602 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
) ||
603 !(wdd
->info
->options
& WDIOF_MAGICCLOSE
))
604 err
= watchdog_stop(wdd
);
606 /* If the watchdog was not stopped, send a keepalive ping */
608 pr_crit("watchdog%d: watchdog did not stop!\n", wdd
->id
);
612 /* make sure that /dev/watchdog can be re-opened */
613 clear_bit(_WDOG_DEV_OPEN
, &wd_data
->status
);
616 mutex_unlock(&wd_data
->lock
);
617 /* Allow the owner module to be unloaded again */
618 module_put(wd_data
->cdev
.owner
);
619 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
623 static const struct file_operations watchdog_fops
= {
624 .owner
= THIS_MODULE
,
625 .write
= watchdog_write
,
626 .unlocked_ioctl
= watchdog_ioctl
,
627 .open
= watchdog_open
,
628 .release
= watchdog_release
,
631 static struct miscdevice watchdog_miscdev
= {
632 .minor
= WATCHDOG_MINOR
,
634 .fops
= &watchdog_fops
,
638 * watchdog_cdev_register: register watchdog character device
639 * @wdd: watchdog device
640 * @devno: character device number
642 * Register a watchdog character device including handling the legacy
643 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
644 * thus we set it up like that.
647 static int watchdog_cdev_register(struct watchdog_device
*wdd
, dev_t devno
)
649 struct watchdog_core_data
*wd_data
;
652 wd_data
= kzalloc(sizeof(struct watchdog_core_data
), GFP_KERNEL
);
655 kref_init(&wd_data
->kref
);
656 mutex_init(&wd_data
->lock
);
659 wdd
->wd_data
= wd_data
;
662 old_wd_data
= wd_data
;
663 watchdog_miscdev
.parent
= wdd
->parent
;
664 err
= misc_register(&watchdog_miscdev
);
666 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
667 wdd
->info
->identity
, WATCHDOG_MINOR
, err
);
669 pr_err("%s: a legacy watchdog module is probably present.\n",
670 wdd
->info
->identity
);
677 /* Fill in the data structures */
678 cdev_init(&wd_data
->cdev
, &watchdog_fops
);
679 wd_data
->cdev
.owner
= wdd
->ops
->owner
;
682 err
= cdev_add(&wd_data
->cdev
, devno
, 1);
684 pr_err("watchdog%d unable to add device %d:%d\n",
685 wdd
->id
, MAJOR(watchdog_devt
), wdd
->id
);
687 misc_deregister(&watchdog_miscdev
);
689 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
696 * watchdog_cdev_unregister: unregister watchdog character device
697 * @watchdog: watchdog device
699 * Unregister watchdog character device and if needed the legacy
700 * /dev/watchdog device.
703 static void watchdog_cdev_unregister(struct watchdog_device
*wdd
)
705 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
707 cdev_del(&wd_data
->cdev
);
709 misc_deregister(&watchdog_miscdev
);
713 mutex_lock(&wd_data
->lock
);
716 mutex_unlock(&wd_data
->lock
);
718 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
721 static struct class watchdog_class
= {
723 .owner
= THIS_MODULE
,
724 .dev_groups
= wdt_groups
,
728 * watchdog_dev_register: register a watchdog device
729 * @wdd: watchdog device
731 * Register a watchdog device including handling the legacy
732 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
733 * thus we set it up like that.
736 int watchdog_dev_register(struct watchdog_device
*wdd
)
742 devno
= MKDEV(MAJOR(watchdog_devt
), wdd
->id
);
744 ret
= watchdog_cdev_register(wdd
, devno
);
748 dev
= device_create_with_groups(&watchdog_class
, wdd
->parent
,
749 devno
, wdd
, wdd
->groups
,
750 "watchdog%d", wdd
->id
);
752 watchdog_cdev_unregister(wdd
);
760 * watchdog_dev_unregister: unregister a watchdog device
761 * @watchdog: watchdog device
763 * Unregister watchdog device and if needed the legacy
764 * /dev/watchdog device.
767 void watchdog_dev_unregister(struct watchdog_device
*wdd
)
769 device_destroy(&watchdog_class
, wdd
->wd_data
->cdev
.dev
);
770 watchdog_cdev_unregister(wdd
);
774 * watchdog_dev_init: init dev part of watchdog core
776 * Allocate a range of chardev nodes to use for watchdog devices
779 int __init
watchdog_dev_init(void)
783 err
= class_register(&watchdog_class
);
785 pr_err("couldn't register class\n");
789 err
= alloc_chrdev_region(&watchdog_devt
, 0, MAX_DOGS
, "watchdog");
791 pr_err("watchdog: unable to allocate char dev region\n");
792 class_unregister(&watchdog_class
);
800 * watchdog_dev_exit: exit dev part of watchdog core
802 * Release the range of chardev nodes used for watchdog devices
805 void __exit
watchdog_dev_exit(void)
807 unregister_chrdev_region(watchdog_devt
, MAX_DOGS
);
808 class_unregister(&watchdog_class
);