[PATCH 1/2] dt-bindings: iio: adc: Add TI ADS1220

[Nguyen Minh Tien]

The ADS1220 is a 24-bit, 2-kSPS, 4-channel delta-sigma ADC from Texas
Instruments with an SPI (mode 1) interface, a programmable gain amplifier,
an internal 2.048V reference and a dedicated DRDY data-ready output.

Add a device tree binding describing the SPI device and its per-input
channel child nodes (single-ended AINx or the multiplexer's differential
pairs), the optional external/AVDD reference selection and the DRDY
interrupt.

Signed-off-by: Nguyen Minh Tien <zizuzacker@xxxxxxxxx>
---
 .../bindings/iio/adc/ti,ads1220.yaml          | 146 ++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,ads1220.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads1220.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads1220.yaml
new file mode 100644
index 000000000..1fedffc2a
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti,ads1220.yaml
@@ -0,0 +1,146 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/ti,ads1220.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments ADS1220 ADC
+
+maintainers:
+  - Nguyen Minh Tien <zizuzacker@xxxxxxxxx>
+
+description:
+  The TI ADS1220 is a precision 24-bit, 2-kSPS, delta-sigma ADC with an SPI
+  (mode 1) interface. It provides two differential or four single-ended inputs
+  through a multiplexer, a programmable gain amplifier (gain 1 to 128), an
+  internal 2.048V reference and oscillator, two programmable excitation current
+  sources and a 50/60Hz rejection filter. A dedicated DRDY output signals when a
+  new conversion result is available.
+
+properties:
+  compatible:
+    const: ti,ads1220
+
+  reg:
+    maxItems: 1
+
+  spi-cpha: true
+
+  interrupts:
+    description: DRDY pin, signals that a new conversion result is ready.
+    maxItems: 1
+
+  avdd-supply:
+    description: Analog power supply (AVDD/AVSS).
+
+  dvdd-supply:
+    description: Digital power supply (DVDD/DGND).
+
+  vref-supply:
+    description:
+      External reference voltage (REFP0/REFN0). If omitted, the internal
+      2.048V reference is used unless ti,vref-avdd is set.
+
+  ti,vref-avdd:
+    type: boolean
+    description:
+      Use the analog supply (AVDD/AVSS) as the conversion reference instead of
+      the internal 2.048V reference. Suited to ratiometric single-supply
+      measurements (for example a potentiometer wired across AVDD), giving a
+      full 0..AVDD input range without an external reference. Ignored when
+      vref-supply is present.
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+  "#io-channel-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - "#address-cells"
+  - "#size-cells"
+  - avdd-supply
+  - dvdd-supply
+
+patternProperties:
+  "^channel@[0-6]$":
+    $ref: adc.yaml
+    type: object
+    description: Represents one ADC input configuration (channel).
+
+    properties:
+      reg:
+        minimum: 0
+        maximum: 6
+
+      diff-channels:
+        description:
+          Differential input pair routable by the ADS1220 multiplexer.
+        oneOf:
+          - items: [const: 0, const: 1]
+          - items: [const: 0, const: 2]
+          - items: [const: 0, const: 3]
+          - items: [const: 1, const: 2]
+          - items: [const: 1, const: 3]
+          - items: [const: 2, const: 3]
+          - items: [const: 1, const: 0]
+          - items: [const: 3, const: 2]
+
+      single-channel:
+        description:
+          Single-ended input channel AINx measured against AVSS.
+        minimum: 0
+        maximum: 3
+
+    oneOf:
+      - required: [diff-channels]
+      - required: [single-channel]
+
+    required:
+      - reg
+
+    unevaluatedProperties: false
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "ti,ads1220";
+            reg = <0>;
+            spi-max-frequency = <2500000>;
+            spi-cpha;
+            interrupt-parent = <&pio>;
+            interrupts = <4 4 IRQ_TYPE_EDGE_FALLING>;
+            avdd-supply = <&reg_vcc3v3>;
+            dvdd-supply = <&reg_vcc3v3>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            #io-channel-cells = <1>;
+
+            channel@0 {
+                reg = <0>;
+                single-channel = <0>;
+            };
+
+            channel@1 {
+                reg = <1>;
+                diff-channels = <0 1>;
+            };
+        };
+    };
+...
-- 
2.34.1