dt-bindings: display: sitronix,st7920: Add DT schema

Add binding for Sitronix ST7920 display.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Iker Pedrosa <ikerpedrosam@gmail.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patch.msgid.link/20251215-st7920-v7-1-36771009ec01@gmail.com

Documentation/devicetree/bindings/display/sitronix,st7920.yaml

@@ -0,0 +1,58 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/sitronix,st7920.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sitronix ST7920 LCD Display Controllers
+
+maintainers:
+  - Iker Pedrosa <ikerpedrosam@gmail.com>
+
+description:
+  The Sitronix ST7920 is a controller for monochrome dot-matrix graphical LCDs,
+  most commonly used for 128x64 pixel displays.
+
+properties:
+  compatible:
+    const: sitronix,st7920
+
+  reg:
+    maxItems: 1
+
+  vdd-supply:
+    description: Regulator that provides 5V Vdd power supply
+
+  reset-gpios:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 600000
+
+required:
+  - compatible
+  - reg
+  - spi-max-frequency
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        display@0 {
+            compatible = "sitronix,st7920";
+            reg = <0>;
+            vdd-supply = <&reg_5v>;
+            reset-gpios = <&gpio 25 GPIO_ACTIVE_LOW>;
+            spi-max-frequency = <600000>;
+            spi-cs-high;
+        };
+    };