dt-bindings: input: tm2-touchkey: convert to yaml

Convert the device tree bindings for tm2-touchkey to the YAML format.

While we're at it, clarify the descriptions a bit to make it clear that
this driver can be used for many different MCUs that all implement
a similar I2C protocol. Depending on the MCU the voltage requirements
may be different, on some devices the controller uses 2.2V, 2.8V or
even 3.3V for vcc-supply instead of 1.8V.
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201203131242.44397-1-stephan@gerhold.netSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/cypress,tm2-touchkey.txt

-Samsung tm2-touchkey
-
-Required properties:
-- compatible:
-    * "cypress,tm2-touchkey" - for the touchkey found on the tm2 board
-    * "cypress,midas-touchkey" - for the touchkey found on midas boards
-    * "cypress,aries-touchkey" - for the touchkey found on aries boards
-    * "coreriver,tc360-touchkey" - for the Coreriver TouchCore 360 touchkey
-- reg: I2C address of the chip.
-- interrupts: interrupt to which the chip is connected (see interrupt
-	binding[0]).
-- vcc-supply : internal regulator output. 1.8V
-- vdd-supply : power supply for IC 3.3V
-
-Optional properties:
-- linux,keycodes: array of keycodes (max 4), default KEY_PHONE and KEY_BACK
-
-[0]: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
-
-Example:
-	&i2c0 {
-		/* ... */
-
-		touchkey@20 {
-			compatible = "cypress,tm2-touchkey";
-			reg = <0x20>;
-			interrupt-parent = <&gpa3>;
-			interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
-			vcc-supply=<&ldo32_reg>;
-			vdd-supply=<&ldo33_reg>;
-			linux,keycodes = <KEY_PHONE KEY_BACK>;
-		};
-	};

Documentation/devicetree/bindings/input/cypress,tm2-touchkey.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/cypress,tm2-touchkey.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Samsung TM2 touch key controller
+
+maintainers:
+  - Stephan Gerhold <stephan@gerhold.net>
+
+description: |
+  Touch key controllers similar to the TM2 can be found in a wide range of
+  Samsung devices. They are implemented using many different MCUs, but use
+  a similar I2C protocol.
+
+allOf:
+  - $ref: input.yaml#
+
+properties:
+  compatible:
+    enum:
+      - cypress,tm2-touchkey
+      - cypress,midas-touchkey
+      - cypress,aries-touchkey
+      - coreriver,tc360-touchkey
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  vdd-supply:
+    description: Optional regulator for LED voltage, 3.3V.
+
+  vcc-supply:
+    description: Optional regulator for MCU, 1.8V-3.3V (depending on MCU).
+
+  linux,keycodes:
+    minItems: 1
+    maxItems: 4
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/input/input.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        touchkey@20 {
+            compatible = "cypress,tm2-touchkey";
+            reg = <0x20>;
+            interrupt-parent = <&gpa3>;
+            interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
+            vcc-supply = <&ldo32_reg>;
+            vdd-supply = <&ldo33_reg>;
+            linux,keycodes = <KEY_MENU KEY_BACK>;
+        };
+    };