dt-bindings: input: Goodix GT7986U SPI HID Touchscreen

The Goodix GT7986U touch controller report touch data according to the
HID protocol through the SPI bus. However, it is incompatible with
Microsoft's HID-over-SPI protocol.

NOTE: these bindings are distinct from the bindings used with the
GT7986U when the chip is running I2C firmware. For some background,
see discussion on the mailing lists in the thread:

https://lore.kernel.org/r/20241018020815.3098263-2-charles.goodix@gmail.com

Signed-off-by: Charles Wang <charles.goodix@gmail.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

Author: charles-goodix

Documentation/devicetree/bindings/input/goodix,gt7986u-spifw.yaml

@@ -0,0 +1,69 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/goodix,gt7986u-spifw.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Goodix GT7986U SPI HID Touchscreen
+
+maintainers:
+  - Charles Wang <charles.goodix@gmail.com>
+
+description: |
+  Supports the Goodix GT7986U touchscreen.
+  This touch controller reports data packaged according to the HID protocol
+  over the SPI bus, but it is incompatible with Microsoft's HID-over-SPI protocol.
+
+  NOTE: these bindings are distinct from the bindings used with the
+  GT7986U when the chip is running I2C firmware. This is because there's
+  not a single device that talks over both I2C and SPI but rather
+  distinct touchscreens that happen to be built with the same ASIC but
+  that are distinct products running distinct firmware.
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - goodix,gt7986u-spifw
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  reset-gpios:
+    maxItems: 1
+
+  spi-max-frequency: true
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - reset-gpios
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      touchscreen@0 {
+        compatible = "goodix,gt7986u-spifw";
+        reg = <0>;
+        interrupt-parent = <&gpio>;
+        interrupts = <25 IRQ_TYPE_LEVEL_LOW>;
+        reset-gpios = <&gpio1 1 GPIO_ACTIVE_LOW>;
+        spi-max-frequency = <10000000>;
+      };
+    };
+
+...