dt-bindings:iio:adc:fsl,imx25-gcq yaml conversion

This binding has a few corners that would have been done different today
but hopefully the yaml schema captures the constraints correctly.

The child node names are not constrained hence the fairly open regexp.
I've also documented the defaults for the two references that the
driver seems to use and copied the value descriptions from the header
because I think they should be in the dt-binding itself.

This is part of a general effort to convert all the IIO bindings
over to yaml

Unfortunately I don't have a current address for Markus, so
have put myself as the maintainer for this binding until someone else
steps up!
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20200909175946.395313-21-jic23@kernel.org

Documentation/devicetree/bindings/iio/adc/fsl,imx25-gcq.txt

-Freescale i.MX25 ADC GCQ device
-
-This is a generic conversion queue device that can convert any of the
-analog inputs using the ADC unit of the i.MX25.
-
-Required properties:
- - compatible: Should be "fsl,imx25-gcq".
- - reg: Should be the register range of the module.
- - interrupts: Should be the interrupt number of the module.
-   Typically this is <1>.
- - #address-cells: Should be <1> (setting for the subnodes)
- - #size-cells: Should be <0> (setting for the subnodes)
-
-Optional properties:
- - vref-ext-supply: The regulator supplying the ADC reference voltage.
-   Required when at least one subnode uses the this reference.
- - vref-xp-supply: The regulator supplying the ADC reference voltage on pin XP.
-   Required when at least one subnode uses this reference.
- - vref-yp-supply: The regulator supplying the ADC reference voltage on pin YP.
-   Required when at least one subnode uses this reference.
-
-Sub-nodes:
-Optionally you can define subnodes which define the reference voltage
-for the analog inputs.
-
-Required properties for subnodes:
- - reg: Should be the number of the analog input.
-     0: xp
-     1: yp
-     2: xn
-     3: yn
-     4: wiper
-     5: inaux0
-     6: inaux1
-     7: inaux2
-Optional properties for subnodes:
- - fsl,adc-refp: specifies the positive reference input as defined in
-     <dt-bindings/iio/adc/fsl-imx25-gcq.h>
- - fsl,adc-refn: specifies the negative reference input as defined in
-     <dt-bindings/iio/adc/fsl-imx25-gcq.h>
-
-Example:
-
-	adc: adc@50030800 {
-		compatible = "fsl,imx25-gcq";
-		reg = <0x50030800 0x60>;
-		interrupt-parent = <&tscadc>;
-		interrupts = <1>;
-		#address-cells = <1>;
-		#size-cells = <0>;
-
-		inaux@5 {
-			reg = <5>;
-			fsl,adc-refp = <MX25_ADC_REFP_INT>;
-			fsl,adc-refn = <MX25_ADC_REFN_NGND>;
-		};
-	};

Documentation/devicetree/bindings/iio/adc/fsl,imx25-gcq.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/fsl,imx25-gcq.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale ADC GCQ device
+
+description:
+  This is a generic conversion queue device that can convert any of the
+  analog inputs using the ADC unit of the i.MX25.
+
+maintainers:
+  - Jonathan Cameron <jic23@kernel.org>
+
+properties:
+  compatible:
+    const: fsl,imx25-gcq
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  vref-ext-supply:
+    description:
+      The regulator supplying the ADC reference voltage.
+      Required when at least one subnode uses the this reference.
+
+  vref-xp-supply:
+    description:
+      The regulator supplying the ADC reference voltage on pin XP.
+      Required when at least one subnode uses this reference.
+
+  vref-yp-supply:
+    description:
+      The regulator supplying the ADC reference voltage on pin YP.
+      Required when at least one subnode uses this reference.
+
+  "#io-channel-cells":
+    const: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - "#address-cells"
+  - "#size-cells"
+
+patternProperties:
+  "[a-z][a-z0-9]+@[0-9a-f]+$":
+    type: object
+    description:
+      Child nodes used to define the reference voltages used for each channel
+
+    properties:
+      reg:
+        description: |
+          Number of the analog input.
+          0: xp
+          1: yp
+          2: xn
+          3: yn
+          4: wiper
+          5: inaux0
+          6: inaux1
+          7: inaux2
+        items:
+          - minimum: 0
+            maximum: 7
+
+      fsl,adc-refp:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: |
+          Specifies the positive reference input as defined in
+          <dt-bindings/iio/adc/fsl-imx25-gcq.h>
+          0: YP voltage reference
+          1: XP voltage reference
+          2: External voltage reference
+          3: Internal voltage reference (default)
+        minimum: 0
+        maximum: 3
+
+      fsl,adc-refn:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: |
+          Specifies the negative reference input as defined in
+          <dt-bindings/iio/adc/fsl-imx25-gcq.h>
+          0: XN ground reference
+          1: YN ground reference
+          2: Internal ground reference
+          3: External ground reference (default)
+        minimum: 0
+        maximum: 3
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/iio/adc/fsl-imx25-gcq.h>
+    soc {
+        #address-cells = <1>;
+        #size-cells = <1>;
+        adc@50030800 {
+            compatible = "fsl,imx25-gcq";
+            reg = <0x50030800 0x60>;
+            interrupt-parent = <&tscadc>;
+            interrupts = <1>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            inaux@5 {
+                reg = <5>;
+                fsl,adc-refp = <MX25_ADC_REFP_INT>;
+                fsl,adc-refn = <MX25_ADC_REFN_NGND>;
+            };
+        };
+    };
+...