dt-bindings: input: touchscreen: convert ad7879 to yaml format

Convert binding doc ad7879.txt to yaml format.
Additional change:
- Add ref to /schemas/spi/spi-peripheral-props.yaml
- Add #gpio-cell
- Remove spi-cpol and spi-cpha in example, the place hold 'spi' can't
correct detect spi-controler.yaml. So these two properties can't
be recongnized.

Fix warning:
arch/arm64/boot/dts/freescale/imx8dx-colibri-aster.dtb:
/bus@5a000000/i2c@5a800000/touchscreen@2c: failed to match any schema with compatible: ['adi,ad7879-1']

Signed-off-by: Frank Li <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/touchscreen/ad7879.txt

···
-* Analog Devices AD7879(-1)/AD7889(-1) touchscreen interface (SPI/I2C)
-
-Required properties:
-- compatible			: for SPI slave, use "adi,ad7879"
-				  for I2C slave, use "adi,ad7879-1"
-- reg				: SPI chipselect/I2C slave address
-				  See spi-bus.txt for more SPI slave properties
-- interrupts			: touch controller interrupt
-- touchscreen-max-pressure	: maximum reported pressure
-- adi,resistance-plate-x	: total resistance of X-plate (for pressure
-				  calculation)
-Optional properties:
-- touchscreen-swapped-x-y	: X and Y axis are swapped (boolean)
-- adi,first-conversion-delay	: 0-12: In 128us steps (starting with 128us)
-				  13  : 2.560ms
-				  14  : 3.584ms
-				  15  : 4.096ms
-				  This property has to be a '/bits/ 8' value
-- adi,acquisition-time		: 0: 2us
-				  1: 4us
-				  2: 8us
-				  3: 16us
-				  This property has to be a '/bits/ 8' value
-- adi,median-filter-size	: 0: disabled
-				  1: 4 measurements
-				  2: 8 measurements
-				  3: 16 measurements
-				  This property has to be a '/bits/ 8' value
-- adi,averaging			: 0: 2 middle values (1 if median disabled)
-				  1: 4 middle values
-				  2: 8 middle values
-				  3: 16 values
-				  This property has to be a '/bits/ 8' value
-- adi,conversion-interval:	: 0    : convert one time only
-				  1-255: 515us + val * 35us (up to 9.440ms)
-				  This property has to be a '/bits/ 8' value
-- gpio-controller		: Switch AUX/VBAT/GPIO pin to GPIO mode
-
-Example:
-
-	touchscreen0@2c {
-		compatible = "adi,ad7879-1";
-		reg = <0x2c>;
-		interrupt-parent = <&gpio1>;
-		interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
-		touchscreen-max-pressure = <4096>;
-		adi,resistance-plate-x = <120>;
-		adi,first-conversion-delay = /bits/ 8 <3>;
-		adi,acquisition-time = /bits/ 8 <1>;
-		adi,median-filter-size = /bits/ 8 <2>;
-		adi,averaging = /bits/ 8 <1>;
-		adi,conversion-interval = /bits/ 8 <255>;
-	};
-
-	touchscreen1@1 {
-		compatible = "adi,ad7879";
-		spi-max-frequency = <5000000>;
-		reg = <1>;
-		spi-cpol;
-		spi-cpha;
-		gpio-controller;
-		interrupt-parent = <&gpio1>;
-		interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
-		touchscreen-max-pressure = <4096>;
-		adi,resistance-plate-x = <120>;
-		adi,first-conversion-delay = /bits/ 8 <3>;
-		adi,acquisition-time = /bits/ 8 <1>;
-		adi,median-filter-size = /bits/ 8 <2>;
-		adi,averaging = /bits/ 8 <1>;
-		adi,conversion-interval = /bits/ 8 <255>;
-	};

Documentation/devicetree/bindings/input/touchscreen/adi,ad7879.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/adi,ad7879.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD7879(-1)/AD7889(-1) touchscreen interface (SPI/I2C)
+
+maintainers:
+  - Frank Li <[e-mail]>
+
+properties:
+  compatible:
+    description: |
+      for SPI slave, use "adi,ad7879"
+      for I2C slave, use "adi,ad7879-1"
+    enum:
+      - adi,ad7879
+      - adi,ad7879-1
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  touchscreen-max-pressure:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: maximum reported pressure
+
+  adi,resistance-plate-x:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: total resistance of X-plate (for pressure calculation)
+
+  touchscreen-swapped-x-y:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: X and Y axis are swapped (boolean)
+
+  adi,first-conversion-delay:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    default: 0
+    minimum: 0
+    maximum: 15
+    description: |
+      0-12: In 128us steps (starting with 128us)
+      13  : 2.560ms
+      14  : 3.584ms
+      15  : 4.096ms
+      This property has to be a '/bits/ 8' value
+
+  adi,acquisition-time:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    default: 0
+    enum: [0, 1, 2, 3]
+    description: |
+      0: 2us
+      1: 4us
+      2: 8us
+      3: 16us
+      This property has to be a '/bits/ 8' value
+
+  adi,median-filter-size:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    default: 0
+    enum: [0, 1, 2, 3]
+    description: |
+      0: disabled
+      1: 4 measurements
+      2: 8 measurements
+      3: 16 measurements
+      This property has to be a '/bits/ 8' value
+
+  adi,averaging:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    default: 0
+    enum: [0, 1, 2, 3]
+    description: |
+      0: 2 middle values (1 if median disabled)
+      1: 4 middle values
+      2: 8 middle values
+      3: 16 values
+      This property has to be a '/bits/ 8' value
+
+  adi,conversion-interval:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    default: 0
+    description: |
+      0    : convert one time only
+      1-255: 515us + val * 35us (up to 9.440ms)
+      This property has to be a '/bits/ 8' value
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        touchscreen0@2c {
+            compatible = "adi,ad7879-1";
+            reg = <0x2c>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
+            touchscreen-max-pressure = <4096>;
+            adi,resistance-plate-x = <120>;
+            adi,first-conversion-delay = /bits/ 8 <3>;
+            adi,acquisition-time = /bits/ 8 <1>;
+            adi,median-filter-size = /bits/ 8 <2>;
+            adi,averaging = /bits/ 8 <1>;
+            adi,conversion-interval = /bits/ 8 <255>;
+        };
+    };
+
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        touchscreen1@1 {
+            compatible = "adi,ad7879";
+            reg = <1>;
+            spi-max-frequency = <5000000>;
+            gpio-controller;
+            #gpio-cells = <1>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
+            touchscreen-max-pressure = <4096>;
+            adi,resistance-plate-x = <120>;
+            adi,first-conversion-delay = /bits/ 8 <3>;
+            adi,acquisition-time = /bits/ 8 <1>;
+            adi,median-filter-size = /bits/ 8 <2>;
+            adi,averaging = /bits/ 8 <1>;
+            adi,conversion-interval = /bits/ 8 <255>;
+        };
+    };