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authorCurtis Klein <curtis.klein@hpe.com>2021-02-03 23:11:30 +0300
committerWim Van Sebroeck <wim@linux-watchdog.org>2021-06-21 09:49:13 +0300
commit7b7d2fdc8c3e3f9fdb3558d674e1eeddc16c7d9e (patch)
tree4a1146ac64f6ad243e74d7d1fd6fcb5fe1e9c119 /drivers/watchdog/Kconfig
parente1138cef88a53eb24c2536cef788a7293824c789 (diff)
downloadlinux-7b7d2fdc8c3e3f9fdb3558d674e1eeddc16c7d9e.tar.xz
watchdog: Add hrtimer-based pretimeout feature
This adds the option to use a hrtimer to generate a watchdog pretimeout event for hardware watchdogs that do not natively support watchdog pretimeouts. With this enabled, all watchdogs will appear to have pretimeout support in userspace. If no pretimeout value is set, there will be no change in the watchdog's behavior. If a pretimeout value is set for a specific watchdog that does not have built-in pretimeout support, a timer will be started that should fire at the specified time before the watchdog timeout would occur. When the watchdog is successfully pinged, the timer will be restarted. If the timer is allowed to fire it will generate a pretimeout event. However because a software timer is used, it may not be able to fire in every circumstance. If the watchdog does support a pretimeout natively, that functionality will be used instead of the hrtimer. The general design of this feaure was inspired by the software watchdog, specifically its own pretimeout implementation. However the software watchdog and this feature are completely independent. They can be used together; with or without CONFIG_SOFT_WATCHDOG_PRETIMEOUT enabled. The main advantage of using the hrtimer pretimeout with a hardware watchdog, compared to running the software watchdog with a hardware watchdog, is that if the hardware watchdog driver is unable to ping the watchdog (e.g. due to a bus or communication error), then the hrtimer pretimeout would still fire whereas the software watchdog would not. Signed-off-by: Curtis Klein <curtis.klein@hpe.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/1612383090-27110-1-git-send-email-curtis.klein@hpe.com Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Diffstat (limited to 'drivers/watchdog/Kconfig')
-rw-r--r--drivers/watchdog/Kconfig8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index fcc61c948f01..7a33e6a6ac23 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -73,6 +73,14 @@ config WATCHDOG_SYSFS
Say Y here if you want to enable watchdog device status read through
sysfs attributes.
+config WATCHDOG_HRTIMER_PRETIMEOUT
+ bool "Enable watchdog hrtimer-based pretimeouts"
+ help
+ Enable this if you want to use a hrtimer timer based pretimeout for
+ watchdogs that do not natively support pretimeout support. Be aware
+ that because this pretimeout functionality uses hrtimers, it may not
+ be able to fire before the actual watchdog fires in some situations.
+
comment "Watchdog Pretimeout Governors"
config WATCHDOG_PRETIMEOUT_GOV