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authorDamien Riegel <damien.riegel@savoirfairelinux.com>2015-11-16 20:27:59 +0300
committerWim Van Sebroeck <wim@iguana.be>2015-12-13 17:27:10 +0300
commit2165bf524da5f5e496d1cdb8c5afae1345ecce1e (patch)
tree75a24ea774d08021e1c45e201ffc9f7a164ca661 /Documentation/watchdog/watchdog-kernel-api.txt
parent1f32f83e5d81c1e99a1c16366e71d5867cd1e364 (diff)
downloadlinux-2165bf524da5f5e496d1cdb8c5afae1345ecce1e.tar.xz
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>
Diffstat (limited to 'Documentation/watchdog/watchdog-kernel-api.txt')
-rw-r--r--Documentation/watchdog/watchdog-kernel-api.txt19
1 files changed, 19 insertions, 0 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index d8b0d3367706..dbc6a65f0bd1 100644
--- 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 routines/operations are:
(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 parameter is invalid). Best practice is
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