dt-bindings: watchdog: gpio: Convert bindings to YAML

Convert the gpio-wdt bindings from text to YAML ones, to permit DT validation.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221107160338.27910-1-marex@denx.de
[robh: add missing 'always-running']
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/watchdog/gpio-wdt.txt

-* 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).
-
-Optional Properties:
-- always-running: If the watchdog timer cannot be disabled, add this flag to
-  have the driver keep toggling the signal without a client. It will only cease
-  to toggle the signal when the device is open and the timeout elapsed.
-
-Example:
-	watchdog: watchdog {
-		/* ADM706 */
-		compatible = "linux,wdt-gpio";
-		gpios = <&gpio3 9 GPIO_ACTIVE_LOW>;
-		hw_algo = "toggle";
-		hw_margin_ms = <1600>;
-	};

Documentation/devicetree/bindings/watchdog/linux,wdt-gpio.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/watchdog/linux,wdt-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: GPIO-controlled Watchdog
+
+maintainers:
+  - Guenter Roeck <linux@roeck-us.net>
+
+properties:
+  compatible:
+    const: linux,wdt-gpio
+
+  gpios:
+    description: gpio connection to WDT reset pin
+    maxItems: 1
+
+  hw_algo:
+    description: The algorithm used by the driver.
+    enum: [ level, toggle ]
+
+  hw_margin_ms:
+    description: Maximum time to reset watchdog circuit (milliseconds).
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  always-running:
+    type: boolean
+    description:
+      If the watchdog timer cannot be disabled, add this flag to have the driver
+      keep toggling the signal without a client.
+      It will only cease to toggle the signal when the device is open and the
+      timeout elapsed.
+
+required:
+  - compatible
+  - gpios
+  - hw_algo
+  - hw_margin_ms
+
+allOf:
+  - $ref: watchdog.yaml#
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    watchdog {
+        compatible = "linux,wdt-gpio";
+        gpios = <&gpio3 9 GPIO_ACTIVE_LOW>;
+        hw_algo = "toggle";
+        hw_margin_ms = <1600>;
+    };