dt-bindings: watchdog: Add Cirrus EP93x

Add device tree bindings for the Cirrus Logic EP93xx watchdog block
used in these SoCs.

Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240909-ep93xx-v12-10-e86ab2423d4b@maquefel.me
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Documentation/devicetree/bindings/watchdog/cirrus,ep9301-wdt.yaml

@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/watchdog/cirrus,ep9301-wdt.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Cirrus Logic EP93xx Watchdog Timer
+
+maintainers:
+  - Nikita Shubin <nikita.shubin@maquefel.me>
+  - Alexander Sverdlin <alexander.sverdlin@gmail.com>
+
+allOf:
+  - $ref: watchdog.yaml#
+
+properties:
+  compatible:
+    oneOf:
+      - const: cirrus,ep9301-wdt
+      - items:
+          - enum:
+              - cirrus,ep9302-wdt
+              - cirrus,ep9307-wdt
+              - cirrus,ep9312-wdt
+              - cirrus,ep9315-wdt
+          - const: cirrus,ep9301-wdt
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    watchdog@80940000 {
+        compatible = "cirrus,ep9301-wdt";
+        reg = <0x80940000 0x08>;
+    };