diff options
Diffstat (limited to 'Documentation/watchdog/watchdog-kernel-api.txt')
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index dd8f912c0576..15a02595ade1 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -52,6 +52,7 @@ struct watchdog_device { unsigned int timeout; unsigned int min_timeout; unsigned int max_timeout; + unsigned int max_hw_heartbeat_ms; struct notifier_block reboot_nb; struct notifier_block restart_nb; void *driver_data; @@ -73,8 +74,18 @@ It contains following fields: 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. * 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. * min_timeout: the watchdog timer's minimum timeout value (in seconds). -* max_timeout: the watchdog timer's maximum timeout value (in seconds). + If set, the minimum configurable value for 'timeout'. +* max_timeout: the watchdog timer's maximum timeout value (in seconds), + as seen from userspace. If set, the maximum configurable value for + 'timeout'. Not used if max_hw_heartbeat_ms is non-zero. +* max_hw_heartbeat_ms: Maximum hardware heartbeat, in milli-seconds. + 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. * 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. @@ -153,7 +164,11 @@ they are supported. These optional routines/operations are: and -EIO for "could not write value to the watchdog". On success this routine should set the timeout value of the watchdog_device to the achieved timeout value (which may be different from the requested one - because the watchdog does not necessarily has a 1 second resolution). + because the watchdog does not necessarily have a 1 second resolution). + Drivers implementing max_hw_heartbeat_ms set the hardware watchdog heartbeat + to the minimum of timeout and max_hw_heartbeat_ms. Those drivers set the + timeout value of the watchdog_device either to the requested timeout value + (if it is larger than max_hw_heartbeat_ms), or to the achieved timeout value. (Note: the WDIOF_SETTIMEOUT 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 |