watchdog: GPIO-controlled watchdog

This patch adds a watchdog driver for devices controlled through GPIO,
(Analog Devices ADM706, Maxim MAX823, National NE555 etc).

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 23 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
new file mode 100644
index 000000000000..37afec194949
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
@@ -0,0 +1,23 @@
+* GPIO-controlled Watchdog
+
+Required Properties:
+- compatible: Should contain "linux,wdt-gpio".
+- gpios: From common gpio binding; gpio connection to WDT reset pin.
+- hw_algo: The algorithm used by the driver. Should be one of the
+  following values:
+  - toggle: Either a high-to-low or a low-to-high transition clears
+    the WDT counter. The watchdog timer is disabled when GPIO is
+    left floating or connected to a three-state buffer.
+  - level: Low or high level starts counting WDT timeout,
+    the opposite level disables the WDT. Active level is determined
+    by the GPIO flags.
+- hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds).
+
+Example:
+        watchdog: watchdog {
+                /* ADM706 */
+                compatible = "linux,wdt-gpio";
+                gpios = <&gpio3 9 GPIO_ACTIVE_LOW>;
+                hw_algo = "toggle";
+                hw_margin_ms = <1600>;
+        };