205 lines
8.4 KiB
Diff
205 lines
8.4 KiB
Diff
From 2165bf524da5f5e496d1cdb8c5afae1345ecce1e Mon Sep 17 00:00:00 2001
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From: Damien Riegel <damien.riegel@savoirfairelinux.com>
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Date: Mon, 16 Nov 2015 12:27:59 -0500
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Subject: watchdog: core: add restart handler support
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Many watchdog drivers implement the same code to register a restart
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handler. This patch provides a generic way to set such a function.
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The patch adds a new restart watchdog operation. If a restart priority
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greater than 0 is needed, the driver can call
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watchdog_set_restart_priority to set it.
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Suggested-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
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Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
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Reviewed-by: Guenter Roeck <linux@roeck-us.net>
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Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
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Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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---
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Documentation/watchdog/watchdog-kernel-api.txt | 19 ++++++++++
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drivers/watchdog/watchdog_core.c | 48 ++++++++++++++++++++++++++
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include/linux/watchdog.h | 6 ++++
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3 files changed, 73 insertions(+)
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--- a/Documentation/watchdog/watchdog-kernel-api.txt
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+++ b/Documentation/watchdog/watchdog-kernel-api.txt
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@@ -53,6 +53,7 @@ struct watchdog_device {
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unsigned int timeout;
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unsigned int min_timeout;
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unsigned int max_timeout;
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+ struct notifier_block restart_nb;
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void *driver_data;
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struct mutex lock;
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unsigned long status;
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@@ -75,6 +76,10 @@ It contains following fields:
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* timeout: the watchdog timer's timeout value (in seconds).
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* min_timeout: the watchdog timer's minimum timeout value (in seconds).
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* max_timeout: the watchdog timer's maximum timeout value (in seconds).
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+* restart_nb: notifier block that is registered for machine restart, for
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+ internal use only. If a watchdog is capable of restarting the machine, it
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+ should define ops->restart. Priority can be changed through
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+ watchdog_set_restart_priority.
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* bootstatus: status of the device after booting (reported with watchdog
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WDIOF_* status bits).
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* driver_data: a pointer to the drivers private data of a watchdog device.
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@@ -100,6 +105,7 @@ struct watchdog_ops {
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unsigned int (*status)(struct watchdog_device *);
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int (*set_timeout)(struct watchdog_device *, unsigned int);
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unsigned int (*get_timeleft)(struct watchdog_device *);
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+ int (*restart)(struct watchdog_device *);
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void (*ref)(struct watchdog_device *);
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void (*unref)(struct watchdog_device *);
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long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
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@@ -164,6 +170,8 @@ they are supported. These optional routi
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(Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
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watchdog's info structure).
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* get_timeleft: this routines returns the time that's left before a reset.
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+* restart: this routine restarts the machine. It returns 0 on success or a
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+ negative errno code for failure.
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* ref: the operation that calls kref_get on the kref of a dynamically
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allocated watchdog_device struct.
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* unref: the operation that calls kref_put on the kref of a dynamically
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@@ -231,3 +239,14 @@ the device tree (if the module timeout p
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to set the default timeout value as timeout value in the watchdog_device and
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then use this function to set the user "preferred" timeout value.
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This routine returns zero on success and a negative errno code for failure.
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+
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+To change the priority of the restart handler the following helper should be
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+used:
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+
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+void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
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+
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+User should follow the following guidelines for setting the priority:
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+* 0: should be called in last resort, has limited restart capabilities
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+* 128: default restart handler, use if no other handler is expected to be
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+ available, and/or if restart is sufficient to restart the entire system
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+* 255: highest priority, will preempt all other restart handlers
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--- a/drivers/watchdog/watchdog_core.c
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+++ b/drivers/watchdog/watchdog_core.c
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@@ -32,6 +32,7 @@
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#include <linux/types.h> /* For standard types */
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#include <linux/errno.h> /* For the -ENODEV/... values */
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#include <linux/kernel.h> /* For printk/panic/... */
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+#include <linux/reboot.h> /* For restart handler */
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#include <linux/watchdog.h> /* For watchdog specific items */
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#include <linux/init.h> /* For __init/__exit/... */
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#include <linux/idr.h> /* For ida_* macros */
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@@ -137,6 +138,41 @@ int watchdog_init_timeout(struct watchdo
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}
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EXPORT_SYMBOL_GPL(watchdog_init_timeout);
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+static int watchdog_restart_notifier(struct notifier_block *nb,
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+ unsigned long action, void *data)
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+{
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+ struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
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+ restart_nb);
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+
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+ int ret;
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+
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+ ret = wdd->ops->restart(wdd);
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+ if (ret)
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+ return NOTIFY_BAD;
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+
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+ return NOTIFY_DONE;
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+}
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+
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+/**
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+ * watchdog_set_restart_priority - Change priority of restart handler
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+ * @wdd: watchdog device
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+ * @priority: priority of the restart handler, should follow these guidelines:
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+ * 0: use watchdog's restart function as last resort, has limited restart
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+ * capabilies
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+ * 128: default restart handler, use if no other handler is expected to be
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+ * available and/or if restart is sufficient to restart the entire system
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+ * 255: preempt all other handlers
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+ *
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+ * If a wdd->ops->restart function is provided when watchdog_register_device is
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+ * called, it will be registered as a restart handler with the priority given
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+ * here.
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+ */
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+void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
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+{
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+ wdd->restart_nb.priority = priority;
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+}
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+EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
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+
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static int __watchdog_register_device(struct watchdog_device *wdd)
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{
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int ret, id = -1, devno;
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@@ -202,6 +238,15 @@ static int __watchdog_register_device(st
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return ret;
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}
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+ if (wdd->ops->restart) {
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+ wdd->restart_nb.notifier_call = watchdog_restart_notifier;
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+
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+ ret = register_restart_handler(&wdd->restart_nb);
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+ if (ret)
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+ dev_warn(wdd->dev, "Cannot register restart handler (%d)\n",
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+ ret);
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+ }
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+
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return 0;
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}
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@@ -238,6 +283,9 @@ static void __watchdog_unregister_device
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if (wdd == NULL)
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return;
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+ if (wdd->ops->restart)
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+ unregister_restart_handler(&wdd->restart_nb);
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+
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devno = wdd->cdev.dev;
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ret = watchdog_dev_unregister(wdd);
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if (ret)
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--- a/include/linux/watchdog.h
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+++ b/include/linux/watchdog.h
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@@ -12,6 +12,7 @@
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#include <linux/bitops.h>
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#include <linux/device.h>
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#include <linux/cdev.h>
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+#include <linux/notifier.h>
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#include <uapi/linux/watchdog.h>
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struct watchdog_ops;
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@@ -26,6 +27,7 @@ struct watchdog_device;
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* @status: The routine that shows the status of the watchdog device.
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* @set_timeout:The routine for setting the watchdog devices timeout value (in seconds).
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* @get_timeleft:The routine that gets the time left before a reset (in seconds).
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+ * @restart: The routine for restarting the machine.
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* @ref: The ref operation for dyn. allocated watchdog_device structs
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* @unref: The unref operation for dyn. allocated watchdog_device structs
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* @ioctl: The routines that handles extra ioctl calls.
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@@ -45,6 +47,7 @@ struct watchdog_ops {
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unsigned int (*status)(struct watchdog_device *);
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int (*set_timeout)(struct watchdog_device *, unsigned int);
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unsigned int (*get_timeleft)(struct watchdog_device *);
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+ int (*restart)(struct watchdog_device *);
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void (*ref)(struct watchdog_device *);
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void (*unref)(struct watchdog_device *);
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long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
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@@ -62,6 +65,7 @@ struct watchdog_ops {
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* @timeout: The watchdog devices timeout value (in seconds).
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* @min_timeout:The watchdog devices minimum timeout value (in seconds).
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* @max_timeout:The watchdog devices maximum timeout value (in seconds).
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+ * @restart_nb: The notifier block to register a restart function.
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* @driver-data:Pointer to the drivers private data.
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* @lock: Lock for watchdog core internal use only.
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* @status: Field that contains the devices internal status bits.
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@@ -88,6 +92,7 @@ struct watchdog_device {
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unsigned int timeout;
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unsigned int min_timeout;
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unsigned int max_timeout;
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+ struct notifier_block restart_nb;
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void *driver_data;
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struct mutex lock;
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unsigned long status;
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@@ -142,6 +147,7 @@ static inline void *watchdog_get_drvdata
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}
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/* drivers/watchdog/watchdog_core.c */
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+void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
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extern int watchdog_init_timeout(struct watchdog_device *wdd,
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unsigned int timeout_parm, struct device *dev);
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extern int watchdog_register_device(struct watchdog_device *);
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