diff options
Diffstat (limited to 'Documentation/watchdog/watchdog-kernel-api.txt')
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 47 |
1 files changed, 42 insertions, 5 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index d8b0d3367706..da7110955f7a 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -53,6 +53,9 @@ struct watchdog_device { unsigned int timeout; unsigned int min_timeout; unsigned int max_timeout; + unsigned int pretimeout; + unsigned int min_pretimeout; + unsigned int max_pretimeout; void *driver_data; struct mutex lock; unsigned long status; @@ -75,6 +78,9 @@ 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). +* pretimeout: the watchdog timer's pretimeout value (in seconds). +* min_pretimeout: the watchdog timer's minimum pretimeout value (in seconds). +* max_pretimeout: the watchdog timer's maximum pretimeout value (in seconds). * 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. @@ -99,6 +105,7 @@ 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 *); void (*ref)(struct watchdog_device *); void (*unref)(struct watchdog_device *); @@ -160,9 +167,19 @@ 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 has a 1 second resolution; + If the driver supports pretimeout, then the timeout value must be greater + than that). (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the watchdog's info structure). +* set_pretimeout: this routine checks and changes the pretimeout of the + watchdog timer device. It returns 0 on success, -EINVAL for "parameter out of + range" and -EIO for "could not write value to the watchdog". On success this + routine should set the pretimeout value of the watchdog_device to the + achieved pretimeout value (which may be different from the requested one + because the watchdog does not necessarily has a 1 second resolution). + (Note: the WDIOF_PRETIMEOUT 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. * ref: the operation that calls kref_get on the kref of a dynamically allocated watchdog_device struct. @@ -226,8 +243,28 @@ extern int watchdog_init_timeout(struct watchdog_device *wdd, unsigned int timeout_parm, struct device *dev); The watchdog_init_timeout function allows you to initialize the timeout field -using the module timeout parameter or by retrieving the timeout-sec property from -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. +using the module timeout parameter or by retrieving the first element of +the timeout-sec property from 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. + +Some watchdog timers have two stage of timeouts (timeout and pretimeout), +to initialize the timeout and pretimeout fields at the same time, the following +function can be used: + +extern int watchdog_init_timeouts(struct watchdog_device *wdd, + unsigned int pretimeout_parm, + unsigned int timeout_parm, + struct device *dev); + +The watchdog_init_timeouts function allows you to initialize the pretimeout and +timeout fields using the module pretimeout and timeout parameter or by +retrieving the elements in the timeout-sec property (the first element is for +timeout, the second one is for pretimeout) from the device tree (if the module +pretimeout and timeout parameter are invalid). +Best practice is to set the default pretimeout and timeout value as pretimeout +and timeout value in the watchdog_device and then use this function to set the +user "preferred" pretimeout value. This routine returns zero on success and a negative errno code for failure. |