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| author | Guenter Roeck <linux@roeck-us.net> | 2016-02-28 13:12:17 -0800 |
|---|---|---|
| committer | Wim Van Sebroeck <wim@iguana.be> | 2016-03-16 21:11:16 +0100 |
| commit | d0684c8a9354953efdea214b437445c00743cf49 (patch) | |
| tree | 0442757196b7ee3e169846a4ef1fa13249870566 /Documentation/watchdog | |
| parent | ee142889e32f564f9b5e57b68b06693ec5473074 (diff) | |
| download | linux-d0684c8a9354953efdea214b437445c00743cf49.tar.gz | |
watchdog: Make stop function optional
Not all hardware watchdogs can be stopped. The driver for such watchdogs would typically only set the WATCHDOG_HW_RUNNING flag in its stop function. Make the stop function optional and set WATCHDOG_HW_RUNNING in the watchdog core if it is not provided. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Diffstat (limited to 'Documentation/watchdog')
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index 954134a5c4a4..9eabca1d9355 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -85,7 +85,8 @@ It contains following fields: If set, the infrastructure will send heartbeats to the watchdog driver if 'timeout' is larger than max_hw_heartbeat_ms, unless WDOG_ACTIVE is set and userspace failed to send a heartbeat for at least 'timeout' - seconds. + seconds. max_hw_heartbeat_ms must be set if a driver does not implement + the stop function. * reboot_nb: notifier block that is registered for reboot notifications, for internal use only. If the driver calls watchdog_stop_on_reboot, watchdog core will stop the watchdog on such notifications. @@ -134,17 +135,20 @@ are: device. The routine needs a pointer to the watchdog timer device structure as a parameter. It returns zero on success or a negative errno code for failure. -* stop: with this routine the watchdog timer device is being stopped. - The routine needs a pointer to the watchdog timer device structure as a - parameter. It returns zero on success or a negative errno code for failure. - Some watchdog timer hardware can only be started and not be stopped. - If a watchdog can not be stopped, the watchdog driver must set the - WDOG_HW_RUNNING flag in its stop function to inform the watchdog core that - the watchdog is still running. Not all watchdog timer hardware supports the same functionality. That's why all other routines/operations are optional. They only need to be provided if they are supported. These optional routines/operations are: +* stop: with this routine the watchdog timer device is being stopped. + The routine needs a pointer to the watchdog timer device structure as a + parameter. It returns zero on success or a negative errno code for failure. + Some watchdog timer hardware can only be started and not be stopped. A + driver supporting such hardware does not have to implement the stop routine. + If a driver has no stop function, the watchdog core will set WDOG_HW_RUNNING + and start calling the driver's keepalive pings function after the watchdog + device is closed. + If a watchdog driver does not implement the stop function, it must set + max_hw_heartbeat_ms. * ping: this is the routine that sends a keepalive ping to the watchdog timer hardware. The routine needs a pointer to the watchdog timer device structure as a |