13  *	by all the watchdog timer drivers.
16  *	misc device: /dev/watchdog.
44 #include <linux/watchdog.h>	/* For watchdog specific items */
50 #include <trace/events/watchdog.h>
52 /* the dev_t structure to store the dynamically allocated watchdog devices */
54 /* Reference to watchdog device behind /dev/watchdog */
84 	 * - Userspace activated the watchdog.  in watchdog_need_worker()
90 	 * Alternatively, if userspace has not opened the watchdog  in watchdog_need_worker()
91 	 * device, we take care of feeding the watchdog if it is  in watchdog_need_worker()
117 	 * To ensure that the watchdog times out wdd->timeout seconds  in watchdog_next_keepalive()
163 		err = wdd->ops->ping(wdd);  /* ping the watchdog */  in __watchdog_ping()
166 		err = wdd->ops->start(wdd); /* restart watchdog */  in __watchdog_ping()
179  * watchdog_ping - ping the watchdog
180  * @wdd: The watchdog device to ping
182  * If the watchdog has no own ping operation then it needs to be
185  * We only ping when the watchdog device is running.
239  * watchdog_start - wrapper to start the watchdog
240  * @wdd: The watchdog device to start
242  * Start the watchdog if it is not active and mark it active.
281  * watchdog_stop - wrapper to stop the watchdog
282  * @wdd: The watchdog device to stop
284  * Stop the watchdog if it is still active and unmark it active.
285  * If the 'nowayout' feature was set, the watchdog cannot be stopped.
298 		pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",  in watchdog_stop()
321  * watchdog_get_status - wrapper to get the watchdog status
322  * @wdd: The watchdog device to get the status from
324  * Get the watchdog's status flags.
327  * Return: watchdog's status flags.
358  * watchdog_set_timeout - set the watchdog timer timeout
359  * @wdd:	The watchdog device to set the timeout for
393  * watchdog_set_pretimeout - set the watchdog timer pretimeout
394  * @wdd:	The watchdog device to set the timeout for
420  * @wdd:	The watchdog device to get the remaining time from
423  * Get the time before a watchdog will reboot (if not pinged).
644  * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
645  * @wdd: The watchdog device to do the ioctl on
646  * @cmd: Watchdog command
663  * watchdog_write - writes to the watchdog
669  * A write to a watchdog device is defined as a keepalive ping.
671  * off the watchdog (if 'nowayout' is not set).
701 	/* someone wrote to us, so we send the watchdog a keepalive ping */  in watchdog_write()
717  * watchdog_ioctl - handle the different ioctl's for the watchdog device
719  * @cmd:	Watchdog command
722  * The watchdog API defines a common set of functions for all watchdogs
790 		/* If the watchdog is active then we send a keepalive ping  in watchdog_ioctl()
791 		 * to make sure that the watchdog keep's running (and if  in watchdog_ioctl()
832  * watchdog_open - open the /dev/watchdog* devices
836  * When the /dev/watchdog* device gets opened, we start the watchdog.
837  * Watch out: the /dev/watchdog device is single open, so we make sure
849 	/* Get the corresponding watchdog device */  in watchdog_open()
856 	/* the watchdog is single open! */  in watchdog_open()
863 	 * If the /dev/watchdog device is open, we don't want the module  in watchdog_open()
884 	 * will take care of an always-running hardware watchdog in  in watchdog_open()
890 	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */  in watchdog_open()
910  * watchdog_release - release the watchdog device
914  * This is the code for when /dev/watchdog gets closed. We will only
915  * stop the watchdog when we have received the magic char (and nowayout
916  * was not set), else the watchdog will keep running.
934 	 * We only stop the watchdog if we received the magic character  in watchdog_release()
944 	/* If the watchdog was not stopped, send a keepalive ping */  in watchdog_release()
946 		pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);  in watchdog_release()
952 	/* make sure that /dev/watchdog can be re-opened */  in watchdog_release()
959 	 * Allow the owner module to be unloaded again unless the watchdog  in watchdog_release()
960 	 * is still running. If the watchdog is still running, it can not  in watchdog_release()
981 	.name		= "watchdog",
986 	.name =		"watchdog",
992  * watchdog_cdev_register - register watchdog character device
993  * @wdd: Watchdog device
995  * Register a watchdog character device including handling the legacy
996  * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1026 	err = dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);  in watchdog_cdev_register()
1045 				pr_err("%s: a legacy watchdog module is probably present.\n",  in watchdog_cdev_register()
1059 		pr_err("watchdog%d unable to add device %d:%d\n",  in watchdog_cdev_register()
1076 	 * If the watchdog is running, prevent its driver from being unloaded,  in watchdog_cdev_register()
1086 			pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",  in watchdog_cdev_register()
1094  * watchdog_cdev_unregister - unregister watchdog character device
1095  * @wdd: Watchdog device
1097  * Unregister watchdog character device and if needed the legacy
1098  * /dev/watchdog device.
1129  * watchdog_dev_register - register a watchdog device
1130  * @wdd: Watchdog device
1132  * Register a watchdog device including handling the legacy
1133  * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1154  * watchdog_dev_unregister - unregister a watchdog device
1155  * @wdd: watchdog device
1157  * Unregister watchdog device and if needed the legacy
1158  * /dev/watchdog device.
1167  * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
1168  * @wdd:		Watchdog device
1171  * Adjusts the last known HW keepalive time for a watchdog timer.
1172  * This is needed if the watchdog is already running when the probe
1174  * function must be called immediately after watchdog registration,
1202  * watchdog_dev_init - init dev part of watchdog core
1204  * Allocate a range of chardev nodes to use for watchdog devices.
1214 		pr_err("Failed to create watchdog kworker\n");  in watchdog_dev_init()
1225 	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");  in watchdog_dev_init()
1227 		pr_err("watchdog: unable to allocate char dev region\n");  in watchdog_dev_init()
1241  * watchdog_dev_exit - exit dev part of watchdog core
1243  * Release the range of chardev nodes used for watchdog devices.
1270 	 * make sure that watchdog worker will not kick in when the wdog is  in watchdog_dev_suspend()
1301 	"Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1306 …"Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (defaul…