dt-bindings: arm: bcm: raspberrypi,bcm2835-firmware: Add touchscreen child node

Convert Raspberry Pi firmware 7" touchscreen controller device tree
binding to json-schema.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250925153144.4082786-2-dario.binacchi@amarulasolutions.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: passgat

Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml

@@ -103,6 +103,28 @@ properties:
       - compatible
       - "#pwm-cells"
 
+  touchscreen:
+    type: object
+    $ref: /schemas/input/touchscreen/touchscreen.yaml#
+    additionalProperties: false
+
+    properties:
+      compatible:
+        const: raspberrypi,firmware-ts
+
+      firmware:
+        deprecated: true
+        description: Phandle to RPi's firmware device node.
+
+      touchscreen-size-x: true
+      touchscreen-size-y: true
+      touchscreen-inverted-x: true
+      touchscreen-inverted-y: true
+      touchscreen-swapped-x-y: true
+
+    required:
+      - compatible
+
 required:
   - compatible
   - mboxes
@@ -135,5 +157,11 @@ examples:
             compatible = "raspberrypi,firmware-poe-pwm";
             #pwm-cells = <2>;
         };
+
+        ts: touchscreen {
+            compatible = "raspberrypi,firmware-ts";
+            touchscreen-size-x = <800>;
+            touchscreen-size-y = <480>;
+        };
     };
 ...