diff options
Diffstat (limited to 'Documentation/watchdog/watchdog-kernel-api.txt')
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index 7f31125c123e..ea277478982f 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -48,8 +48,10 @@ struct watchdog_device { const struct attribute_group **groups; const struct watchdog_info *info; const struct watchdog_ops *ops; + const struct watchdog_governor *gov; unsigned int bootstatus; unsigned int timeout; + unsigned int pretimeout; unsigned int min_timeout; unsigned int max_timeout; unsigned int min_hw_heartbeat_ms; @@ -74,9 +76,11 @@ It contains following fields: * info: a pointer to a watchdog_info structure. This structure gives some additional information about the watchdog timer itself. (Like it's unique name) * ops: a pointer to the list of watchdog operations that the watchdog supports. +* gov: a pointer to the assigned watchdog device pretimeout governor or NULL. * timeout: the watchdog timer's timeout value (in seconds). This is the time after which the system will reboot if user space does not send a heartbeat request if WDOG_ACTIVE is set. +* pretimeout: the watchdog timer's pretimeout value (in seconds). * min_timeout: the watchdog timer's minimum timeout value (in seconds). If set, the minimum configurable value for 'timeout'. * max_timeout: the watchdog timer's maximum timeout value (in seconds), @@ -121,6 +125,7 @@ struct watchdog_ops { int (*ping)(struct watchdog_device *); unsigned int (*status)(struct watchdog_device *); int (*set_timeout)(struct watchdog_device *, unsigned int); + int (*set_pretimeout)(struct watchdog_device *, unsigned int); unsigned int (*get_timeleft)(struct watchdog_device *); int (*restart)(struct watchdog_device *); void (*ref)(struct watchdog_device *) __deprecated; @@ -188,6 +193,23 @@ they are supported. These optional routines/operations are: If set_timeout is not provided but, WDIOF_SETTIMEOUT is set, the watchdog infrastructure updates the timeout value of the watchdog_device internally to the requested value. + If the pretimeout feature is used (WDIOF_PRETIMEOUT), then set_timeout must + also take care of checking if pretimeout is still valid and set up the timer + accordingly. This can't be done in the core without races, so it is the + duty of the driver. +* set_pretimeout: this routine checks and changes the pretimeout value of + the watchdog. It is optional because not all watchdogs support pretimeout + notification. The timeout value is not an absolute time, but the number of + seconds before the actual timeout would happen. It returns 0 on success, + -EINVAL for "parameter out of range" and -EIO for "could not write value to + the watchdog". A value of 0 disables pretimeout notification. + (Note: the WDIOF_PRETIMEOUT needs to be set in the options field of the + watchdog's info structure). + If the watchdog driver does not have to perform any action but setting the + watchdog_device.pretimeout, this callback can be omitted. That means if + set_pretimeout is not provided but WDIOF_PRETIMEOUT is set, the watchdog + infrastructure updates the pretimeout value of the watchdog_device internally + to the requested value. * 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. @@ -268,3 +290,14 @@ User should follow the following guidelines for setting the priority: * 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 + +To raise a pretimeout notification, the following function should be used: + +void watchdog_notify_pretimeout(struct watchdog_device *wdd) + +The function can be called in the interrupt context. If watchdog pretimeout +governor framework (kbuild CONFIG_WATCHDOG_PRETIMEOUT_GOV symbol) is enabled, +an action is taken by a preconfigured pretimeout governor preassigned to +the watchdog device. If watchdog pretimeout governor framework is not +enabled, watchdog_notify_pretimeout() prints a notification message to +the kernel log buffer. |