From 7702961ce8dceed94f3efe401e39dc62ccac0e70 Mon Sep 17 00:00:00 2001 From: Ahmad Fatoum Date: Mon, 26 Apr 2021 13:34:08 +0200 Subject: Documentation: user: watchdog: sync with current state Since most of the documentation was written, the watchdog framework has gained three more device parameters. Document them. Signed-off-by: Ahmad Fatoum Link: https://lore.barebox.org/20210426113408.24903-2-a.fatoum@pengutronix.de Signed-off-by: Sascha Hauer --- Documentation/user/watchdog.rst | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-) diff --git a/Documentation/user/watchdog.rst b/Documentation/user/watchdog.rst index 02bd576a89..ff400317a0 100644 --- a/Documentation/user/watchdog.rst +++ b/Documentation/user/watchdog.rst @@ -57,6 +57,9 @@ measured in seconds: barebox@DPTechnics DPT-Module:/ devinfo wdog0 Parameters: autoping: 1 (type: bool) + priority: 100 (type: uint32) + running: 1 (type: enum) (values: "unknown", "1", "0") + seconds_to_expire: 7 (type: uint32) timeout_cur: 7 (type: uint32) timeout_max: 10 (type: uint32) @@ -67,6 +70,34 @@ Use barebox' environment to persist these changes between reboots: nv dev.wdog0.autoping=1 nv dev.wdog0.timeout_cur=7 +Watchdog State +~~~~~~~~~~~~~~ + +To check whether a watchdog is currently running, the ``running`` device +parameter can be consulted. Not all watchdog devices (or their drivers) +provide the information whether a watchdog was running prior to barebox. +In that case, the parameter will contain the value ``unknown``. + +Watchdogs started by barebox can be monitored using the +``seconds_to_expire`` parameter. A well-behaving system of watchdog +device, watchdog driver and clocksource should reset as soon as the +count down reaches zero. + +To manually start a watchdog, :ref:`command_wd` can be used. + +Default Watchdog +~~~~~~~~~~~~~~~~ + +barebox supports multiple concurrent watchdogs. The default watchdog used +with :ref:`command_wd`, ``boot.watchdog_timeout`` and :ref:`command_boot`'s +``-w`` option is the one with the highest positive priority. +If multiple watchdogs share the same priority, only one will be affected. + +The priority is initially set by drivers and can be overridden in the +device tree or via the ``priority`` device parameter. Normally, watchdogs +that have a wider effect should be given the higher priority (e.g. +PMIC watchdog resetting the board vs. SoC's watchdog resetting only itself). + Boot Watchdog Timeout ~~~~~~~~~~~~~~~~~~~~~ @@ -85,7 +116,4 @@ or persistently by nv boot.watchdog_timeout=10 where the used value again is measured in seconds. - -On a system with multiple watchdogs, the watchdog with the highest positive -priority is the one affected by the ``boot.watchdog_timeout`` parameter. If -multiple watchdogs share the same priority, only one will be started. +Only the default watchdog will be started. -- cgit v1.2.3