watchdog: Add ChromeOS EC-based watchdog driver

Embedded Controller (EC) present on Chromebook devices
can be used as a watchdog.
Implement a driver to support it.

Signed-off-by: Lukasz Majczak <lma@chromium.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240126095721.782782-3-lma@chromium.org
Signed-off-by: Lee Jones <lee@kernel.org>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 7d22051..4700b21 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -181,6 +181,17 @@
 	  watchdog. Alternatively say M to compile the driver as a module,
 	  which will be called bd9576_wdt.
 
+config CROS_EC_WATCHDOG
+	tristate "ChromeOS EC-based watchdog"
+	select WATCHDOG_CORE
+	depends on CROS_EC
+	help
+	  Watchdog driver for Chromebook devices equipped with embedded controller.
+	  Trigger event is recorded in EC and checked on the subsequent boot.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called cros_ec_wdt.
+
 config DA9052_WATCHDOG
 	tristate "Dialog DA9052 Watchdog"
 	depends on PMIC_DA9052 || COMPILE_TEST