dt-bindings: input: touchscreen: add hynitron cst816x series

Add documentation for Hynitron CST816x series touchscreen bindings.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Oleh Kuzhylnyi <kuzhylol@gmail.com>
Link: https://lore.kernel.org/r/20250921125939.249788-1-kuzhylol@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: kuzhylol

Documentation/devicetree/bindings/input/touchscreen/hynitron,cst816x.yaml

@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/hynitron,cst816x.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Hynitron CST816x Series Capacitive Touch controller
+
+maintainers:
+  - Oleh Kuzhylnyi <kuzhylol@gmail.com>
+
+description: |
+  Bindings for CST816x high performance self-capacitance touch chip series
+  with single point gesture and real two-point operation.
+
+properties:
+  compatible:
+    enum:
+      - hynitron,cst816s
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  reset-gpios:
+    maxItems: 1
+
+  linux,keycodes:
+    minItems: 1
+    items:
+      - description: Slide up gesture
+      - description: Slide down gesture
+      - description: Slide left gesture
+      - description: Slide right gesture
+      - description: Long press gesture
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/input/linux-event-codes.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        touchscreen@15 {
+            compatible = "hynitron,cst816s";
+            reg = <0x15>;
+            interrupt-parent = <&gpio0>;
+            interrupts = <4 IRQ_TYPE_EDGE_RISING>;
+            reset-gpios = <&gpio 17 GPIO_ACTIVE_LOW>;
+            linux,keycodes = <KEY_UP>, <KEY_DOWN>, <KEY_LEFT>, <KEY_RIGHT>,
+                             <BTN_TOOL_TRIPLETAP>;
+        };
+    };
+
+...