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authorAhmad Fatoum <a.fatoum@pengutronix.de>2021-04-26 13:34:08 +0200
committerSascha Hauer <s.hauer@pengutronix.de>2021-05-03 12:38:19 +0200
commit7702961ce8dceed94f3efe401e39dc62ccac0e70 (patch)
tree2eba6b936620fc7d2cc998904f6584cdcb6399e0
parent17bedd93623f27e773775b7164d27b7e9edfdf4b (diff)
downloadbarebox-7702961ce8dceed94f3efe401e39dc62ccac0e70.tar.gz
barebox-7702961ce8dceed94f3efe401e39dc62ccac0e70.tar.xz
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 <a.fatoum@pengutronix.de> Link: https://lore.barebox.org/20210426113408.24903-2-a.fatoum@pengutronix.de Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
-rw-r--r--Documentation/user/watchdog.rst36
1 files changed, 32 insertions, 4 deletions
diff --git a/Documentation/user/watchdog.rst b/Documentation/user/watchdog.rst
index 02bd576a8..ff400317a 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.