dt-bindings: iio: adc: ROHM BD79112 ADC/GPIO

The ROHM BD79112 is an ADC/GPIO with 32 channels. The channel inputs can
be used as ADC or GPIO. Using the GPIOs as IRQ sources isn't supported.

The ADC is 12-bit, supporting input voltages up to 5.7V, and separate I/O
voltage supply. Maximum SPI clock rate is 20 MHz (10 MHz with
daisy-chain configuration) and maximum sampling rate is 1MSPS.

Add a device tree binding document for the ROHM BD79112.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/rohm,bd79112.yaml

@@ -0,0 +1,104 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/rohm,bd79112.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ROHM BD79112 ADC/GPO
+
+maintainers:
+  - Matti Vaittinen <mazziesaccount@gmail.com>
+
+description: |
+  The ROHM BD79112 is a 12-bit, 32-channel, SAR ADC. ADC input pins can be
+  also configured as general purpose inputs/outputs. SPI should use MODE 3.
+
+properties:
+  compatible:
+    const: rohm,bd79112
+
+  reg:
+    maxItems: 1
+
+  spi-cpha: true
+  spi-cpol: true
+
+  gpio-controller: true
+  "#gpio-cells":
+    const: 2
+
+  vdd-supply: true
+
+  iovdd-supply: true
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  "^channel@([0-9]|[12][0-9]|3[01])$":
+    type: object
+    $ref: /schemas/iio/adc/adc.yaml#
+    description: Represents ADC channel. Omitted channels' inputs are GPIOs.
+
+    properties:
+      reg:
+        description: AIN pin number
+        minimum: 0
+        maximum: 31
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - iovdd-supply
+  - vdd-supply
+  - spi-cpha
+  - spi-cpol
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        adc: adc@0 {
+            compatible = "rohm,bd79112";
+            reg = <0x0>;
+
+            spi-cpha;
+            spi-cpol;
+
+            vdd-supply = <&dummyreg>;
+            iovdd-supply = <&dummyreg>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            gpio-controller;
+            #gpio-cells = <2>;
+
+            channel@0 {
+                reg = <0>;
+            };
+            channel@1 {
+                reg = <1>;
+            };
+            channel@2 {
+                reg = <2>;
+            };
+            channel@16 {
+                reg = <16>;
+            };
+            channel@20 {
+                reg = <20>;
+            };
+        };
+    };