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