dt-bindings: display: elgin,jg10309-01: Add own binding

Currently, the compatible 'elgin,jg10309-01' is documented inside
trivial-devices.yaml, but it does not fit well there as it requires
extra properties such as spi-max-frequency, spi-cpha, and spi-cpol.

This causes the following dt-schema warnings:

make CHECK_DTBS=y rockchip/rv1108-elgin-r1.dtb -j12

  DTC [C] arch/arm/boot/dts/rockchip/rv1108-elgin-r1.dtb
rv1108-elgin-r1.dtb:display@0: 'spi-cpha', 'spi-cpol' do not match any of the regexes:
...

Fix this problem by introducing a specific binding for the Elgin
JG10309-01 SPI-controlled display.

Signed-off-by: Fabio Estevam <[email protected]>
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rob Herring (Arm) <[email protected]>

Documentation/devicetree/bindings/display/elgin,jg10309-01.yaml

@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/elgin,jg10309-01.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Elgin JG10309-01 SPI-controlled display
+
+maintainers:
+  - Fabio Estevam <[email protected]>
+
+description: |
+  The Elgin JG10309-01 SPI-controlled display is used on the RV1108-Elgin-r1
+  board and is a custom display.
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    const: elgin,jg10309-01
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 24000000
+
+  spi-cpha: true
+
+  spi-cpol: true
+
+required:
+  - compatible
+  - reg
+  - spi-cpha
+  - spi-cpol
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        display@0 {
+            compatible = "elgin,jg10309-01";
+            reg = <0>;
+            spi-max-frequency = <24000000>;
+            spi-cpha;
+            spi-cpol;
+        };
+    };

Documentation/devicetree/bindings/trivial-devices.yaml

@@ -101,8 +101,6 @@ properties:
           - domintech,dmard09
             # DMARD10: 3-axis Accelerometer
           - domintech,dmard10
-            # Elgin SPI-controlled LCD
-          - elgin,jg10309-01
             # MMA7660FC: 3-Axis Orientation/Motion Detection Sensor
           - fsl,mma7660
             # MMA8450Q: Xtrinsic Low-power, 3-axis Xtrinsic Accelerometer