13  *	by all the watchdog timer drivers.
16  *	misc device: /dev/watchdog.
45 #include <linux/watchdog.h>	/* For watchdog specific items */
51 #include <trace/events/watchdog.h>
53 /* the dev_t structure to store the dynamically allocated watchdog devices */
55 /* Reference to watchdog device behind /dev/watchdog */
85 	 * - Userspace activated the watchdog.  in watchdog_need_worker()
91 	 * Alternatively, if userspace has not opened the watchdog  in watchdog_need_worker()
92 	 * device, we take care of feeding the watchdog if it is  in watchdog_need_worker()
118 	 * To ensure that the watchdog times out wdd->timeout seconds  in watchdog_next_keepalive()
164 		err = wdd->ops->ping(wdd);  /* ping the watchdog */  in __watchdog_ping()
167 		err = wdd->ops->start(wdd); /* restart watchdog */  in __watchdog_ping()
180  * watchdog_ping - ping the watchdog
181  * @wdd: The watchdog device to ping
183  * If the watchdog has no own ping operation then it needs to be
186  * We only ping when the watchdog device is running.
240  * watchdog_start - wrapper to start the watchdog
241  * @wdd: The watchdog device to start
243  * Start the watchdog if it is not active and mark it active.
283  * watchdog_stop - wrapper to stop the watchdog
284  * @wdd: The watchdog device to stop
286  * Stop the watchdog if it is still active and unmark it active.
287  * If the 'nowayout' feature was set, the watchdog cannot be stopped.
300 		pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",  in watchdog_stop()
323  * watchdog_get_status - wrapper to get the watchdog status
324  * @wdd: The watchdog device to get the status from
326  * Get the watchdog's status flags.
329  * Return: watchdog's status flags.
360  * watchdog_set_timeout - set the watchdog timer timeout
361  * @wdd:	The watchdog device to set the timeout for
395  * watchdog_set_pretimeout - set the watchdog timer pretimeout
396  * @wdd:	The watchdog device to set the timeout for
422  * @wdd:	The watchdog device to get the remaining time from
425  * Get the time before a watchdog will reboot (if not pinged).
666  * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
667  * @wdd: The watchdog device to do the ioctl on
668  * @cmd: Watchdog command
685  * watchdog_write - writes to the watchdog
691  * A write to a watchdog device is defined as a keepalive ping.
693  * off the watchdog (if 'nowayout' is not set).
723 	/* someone wrote to us, so we send the watchdog a keepalive ping */  in watchdog_write()
739  * watchdog_ioctl - handle the different ioctl's for the watchdog device
741  * @cmd:	Watchdog command
744  * The watchdog API defines a common set of functions for all watchdogs
812 		/* If the watchdog is active then we send a keepalive ping  in watchdog_ioctl()
813 		 * to make sure that the watchdog keep's running (and if  in watchdog_ioctl()
854  * watchdog_open - open the /dev/watchdog* devices
858  * When the /dev/watchdog* device gets opened, we start the watchdog.
859  * Watch out: the /dev/watchdog device is single open, so we make sure
871 	/* Get the corresponding watchdog device */  in watchdog_open()
878 	/* the watchdog is single open! */  in watchdog_open()
885 	 * If the /dev/watchdog device is open, we don't want the module  in watchdog_open()
906 	 * will take care of an always-running hardware watchdog in  in watchdog_open()
912 	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */  in watchdog_open()
932  * watchdog_release - release the watchdog device
936  * This is the code for when /dev/watchdog gets closed. We will only
937  * stop the watchdog when we have received the magic char (and nowayout
938  * was not set), else the watchdog will keep running.
956 	 * We only stop the watchdog if we received the magic character  in watchdog_release()
966 	/* If the watchdog was not stopped, send a keepalive ping */  in watchdog_release()
968 		pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);  in watchdog_release()
974 	/* make sure that /dev/watchdog can be re-opened */  in watchdog_release()
981 	 * Allow the owner module to be unloaded again unless the watchdog  in watchdog_release()
982 	 * is still running. If the watchdog is still running, it can not  in watchdog_release()
1003 	.name		= "watchdog",
1008 	.name =		"watchdog",
1013  * watchdog_cdev_register - register watchdog character device
1014  * @wdd: Watchdog device
1016  * Register a watchdog character device including handling the legacy
1017  * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1047 	err = dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);  in watchdog_cdev_register()
1066 				pr_err("%s: a legacy watchdog module is probably present.\n",  in watchdog_cdev_register()
1081 		pr_err("watchdog%d unable to add device %d:%d\n",  in watchdog_cdev_register()
1096 	 * If the watchdog is running, prevent its driver from being unloaded,  in watchdog_cdev_register()
1106 			pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",  in watchdog_cdev_register()
1114  * watchdog_cdev_unregister - unregister watchdog character device
1115  * @wdd: Watchdog device
1117  * Unregister watchdog character device and if needed the legacy
1118  * /dev/watchdog device.
1149  * watchdog_dev_register - register a watchdog device
1150  * @wdd: Watchdog device
1152  * Register a watchdog device including handling the legacy
1153  * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1174  * watchdog_dev_unregister - unregister a watchdog device
1175  * @wdd: watchdog device
1177  * Unregister watchdog device and if needed the legacy
1178  * /dev/watchdog device.
1187  * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
1188  * @wdd:		Watchdog device
1191  * Adjusts the last known HW keepalive time for a watchdog timer.
1192  * This is needed if the watchdog is already running when the probe
1194  * function must be called immediately after watchdog registration,
1222  * watchdog_dev_init - init dev part of watchdog core
1224  * Allocate a range of chardev nodes to use for watchdog devices.
1234 		pr_err("Failed to create watchdog kworker\n");  in watchdog_dev_init()
1245 	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");  in watchdog_dev_init()
1247 		pr_err("watchdog: unable to allocate char dev region\n");  in watchdog_dev_init()
1261  * watchdog_dev_exit - exit dev part of watchdog core
1263  * Release the range of chardev nodes used for watchdog devices.
1290 	 * make sure that watchdog worker will not kick in when the wdog is  in watchdog_dev_suspend()
1321 	"Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1326 …"Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (defaul…