11  *	by all the watchdog timer drivers.
14  *	misc device: /dev/watchdog.
47 #include <linux/watchdog.h>	/* For watchdog specific items */
56  * struct watchdog_core_data - watchdog core internal data
57  * @dev:	The watchdog's internal device
58  * @cdev:	The watchdog's Character device.
59  * @wdd:	Pointer to watchdog device.
60  * @lock:	Lock for watchdog core.
61  * @status:	Watchdog core internal status bits.
78 /* the dev_t structure to store the dynamically allocated watchdog devices */
80 /* Reference to watchdog device behind /dev/watchdog */
97 	 * - Userspace activated the watchdog.  in watchdog_need_worker()
103 	 * Alternatively, if userspace has not opened the watchdog  in watchdog_need_worker()
104 	 * device, we take care of feeding the watchdog if it is  in watchdog_need_worker()
129 	 * To ensure that the watchdog times out wdd->timeout seconds  in watchdog_next_keepalive()
174 		err = wdd->ops->ping(wdd);  /* ping the watchdog */  in __watchdog_ping()
176 		err = wdd->ops->start(wdd); /* restart watchdog */  in __watchdog_ping()
184  *	watchdog_ping: ping the watchdog.
185  *	@wdd: the watchdog device to ping
189  *	If the watchdog has no own ping operation then it needs to be
192  *	We only ping when the watchdog device is running.
238  *	watchdog_start: wrapper to start the watchdog.
239  *	@wdd: the watchdog device to start
243  *	Start the watchdog if it is not active and mark it active.
275  *	watchdog_stop: wrapper to stop the watchdog.
276  *	@wdd: the watchdog device to stop
280  *	Stop the watchdog if it is still active and unmark it active.
283  *	If the 'nowayout' feature was set, the watchdog cannot be stopped.
294 		pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",  in watchdog_stop()
315  *	watchdog_get_status: wrapper to get the watchdog status
316  *	@wdd: the watchdog device to get the status from
320  *	Get the watchdog's status flags.
349  *	watchdog_set_timeout: set the watchdog timer timeout
350  *	@wdd: the watchdog device to set the timeout for
382  *	watchdog_set_pretimeout: set the watchdog timer pretimeout
383  *	@wdd: the watchdog device to set the timeout for
408  *	@wdd: the watchdog device to get the remaining time from
413  *	Get the time before a watchdog will reboot (if not pinged).
594  *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
595  *	@wdd: the watchdog device to do the ioctl on
596  *	@cmd: watchdog command
612  *	watchdog_write: writes to the watchdog.
618  *	A write to a watchdog device is defined as a keepalive ping.
620  *	off the watchdog (if 'nowayout' is not set).
649 	/* someone wrote to us, so we send the watchdog a keepalive ping */  in watchdog_write()
665  *	watchdog_ioctl: handle the different ioctl's for the watchdog device.
667  *	@cmd: watchdog command
670  *	The watchdog API defines a common set of functions for all watchdogs
736 		/* If the watchdog is active then we send a keepalive ping  in watchdog_ioctl()
737 		 * to make sure that the watchdog keep's running (and if  in watchdog_ioctl()
778  *	watchdog_open: open the /dev/watchdog* devices.
782  *	When the /dev/watchdog* device gets opened, we start the watchdog.
783  *	Watch out: the /dev/watchdog device is single open, so we make sure
794 	/* Get the corresponding watchdog device */  in watchdog_open()
801 	/* the watchdog is single open! */  in watchdog_open()
808 	 * If the /dev/watchdog device is open, we don't want the module  in watchdog_open()
826 	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */  in watchdog_open()
846  *	watchdog_release: release the watchdog device.
850  *	This is the code for when /dev/watchdog gets closed. We will only
851  *	stop the watchdog when we have received the magic char (and nowayout
852  *	was not set), else the watchdog will keep running.
869 	 * We only stop the watchdog if we received the magic character  in watchdog_release()
879 	/* If the watchdog was not stopped, send a keepalive ping */  in watchdog_release()
881 		pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);  in watchdog_release()
887 	/* make sure that /dev/watchdog can be re-opened */  in watchdog_release()
894 	 * Allow the owner module to be unloaded again unless the watchdog  in watchdog_release()
895 	 * is still running. If the watchdog is still running, it can not  in watchdog_release()
915 	.name		= "watchdog",
920 	.name =		"watchdog",
926  *	watchdog_cdev_register: register watchdog character device
927  *	@wdd: watchdog device
929  *	Register a watchdog character device including handling the legacy
930  *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
959 	dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);  in watchdog_cdev_register()
973 				pr_err("%s: a legacy watchdog module is probably present.\n",  in watchdog_cdev_register()
987 		pr_err("watchdog%d unable to add device %d:%d\n",  in watchdog_cdev_register()
1003 	 * If the watchdog is running, prevent its driver from being unloaded,  in watchdog_cdev_register()
1012 			pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",  in watchdog_cdev_register()
1020  *	watchdog_cdev_unregister: unregister watchdog character device
1021  *	@watchdog: watchdog device
1023  *	Unregister watchdog character device and if needed the legacy
1024  *	/dev/watchdog device.
1054  *	watchdog_dev_register: register a watchdog device
1055  *	@wdd: watchdog device
1057  *	Register a watchdog device including handling the legacy
1058  *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
1078  *	watchdog_dev_unregister: unregister a watchdog device
1079  *	@watchdog: watchdog device
1081  *	Unregister watchdog device and if needed the legacy
1082  *	/dev/watchdog device.
1092  *	watchdog_dev_init: init dev part of watchdog core
1094  *	Allocate a range of chardev nodes to use for watchdog devices
1104 		pr_err("Failed to create watchdog kworker\n");  in watchdog_dev_init()
1115 	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");  in watchdog_dev_init()
1117 		pr_err("watchdog: unable to allocate char dev region\n");  in watchdog_dev_init()
1131  *	watchdog_dev_exit: exit dev part of watchdog core
1133  *	Release the range of chardev nodes used for watchdog devices
1145 	"Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="