dt-bindings: iio/adc: Convert ingenic-adc docs to YAML.

Convert the textual documentation of Device Tree bindings for the
Ingenic JZ47xx SoCs ADC controller to YAML.

The `interrupts` property is now explicitly listed and marked as
required. While missing from the previous textual documentation, this
property has been used with all the boards which probe this driver.
Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
Tested-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt

-* Ingenic JZ47xx ADC controller IIO bindings
-
-Required properties:
-
-- compatible: Should be one of:
-  * ingenic,jz4725b-adc
-  * ingenic,jz4740-adc
-  * ingenic,jz4770-adc
-- reg: ADC controller registers location and length.
-- clocks: phandle to the SoC's ADC clock.
-- clock-names: Must be set to "adc".
-- #io-channel-cells: Must be set to <1> to indicate channels are selected
-  by index.
-
-ADC clients must use the format described in iio-bindings.txt, giving
-a phandle and IIO specifier pair ("io-channels") to the ADC controller.
-
-Example:
-
-#include <dt-bindings/iio/adc/ingenic,adc.h>
-
-adc: adc@10070000 {
-	compatible = "ingenic,jz4740-adc";
-	#io-channel-cells = <1>;
-
-	reg = <0x10070000 0x30>;
-
-	clocks = <&cgu JZ4740_CLK_ADC>;
-	clock-names = "adc";
-
-	interrupt-parent = <&intc>;
-	interrupts = <18>;
-};
-
-adc-keys {
-	...
-	compatible = "adc-keys";
-	io-channels = <&adc INGENIC_ADC_AUX>;
-	io-channel-names = "buttons";
-	...
-};
-
-battery {
-	...
-	compatible = "ingenic,jz4740-battery";
-	io-channels = <&adc INGENIC_ADC_BATTERY>;
-	io-channel-names = "battery";
-	...
-};

Documentation/devicetree/bindings/iio/adc/ingenic,adc.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2019-2020 Artur Rojek
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/iio/adc/ingenic,adc.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Ingenic JZ47xx ADC controller IIO bindings
+
+maintainers:
+  - Artur Rojek <contact@artur-rojek.eu>
+
+description: >
+  Industrial I/O subsystem bindings for ADC controller found in
+  Ingenic JZ47xx SoCs.
+
+  ADC clients must use the format described in iio-bindings.txt, giving
+  a phandle and IIO specifier pair ("io-channels") to the ADC controller.
+
+properties:
+  compatible:
+    enum:
+      - ingenic,jz4725b-adc
+      - ingenic,jz4740-adc
+      - ingenic,jz4770-adc
+
+  '#io-channel-cells':
+    const: 1
+    description:
+      Must be set to <1> to indicate channels are selected by index.
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: adc
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - '#io-channel-cells'
+  - reg
+  - clocks
+  - clock-names
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/jz4740-cgu.h>
+    #include <dt-bindings/iio/adc/ingenic,adc.h>
+
+    adc@10070000 {
+            compatible = "ingenic,jz4740-adc";
+            #io-channel-cells = <1>;
+
+            reg = <0x10070000 0x30>;
+
+            clocks = <&cgu JZ4740_CLK_ADC>;
+            clock-names = "adc";
+
+            interrupt-parent = <&intc>;
+            interrupts = <18>;
+    };