dt-bindings: adc: ad7173: add support for ad411x

Add support for: AD4111, AD4112, AD4114, AD4115, AD4116.

AD411x family ADCs support a VCOM pin. The purpose of this pin is to
offer a dedicated common-mode voltage input for single-ended channels.
This pin is specified as supporting a differential channel with VIN10 on
model AD4116.

AD4111/AD4112 support current channels. Support is implemented using
single-channel and "adi,current-channel".
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Dumitru Ceclan <dumitru.ceclan@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20240607-ad4111-v7-2-97e3855900a0@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml

@@ -19,7 +19,18 @@ description: |
   primarily for measurement of signals close to DC but also delivers
   outstanding performance with input bandwidths out to ~10kHz.
 
+  Analog Devices AD411x ADC's:
+  The AD411X family encompasses a series of low power, low noise, 24-bit,
+  sigma-delta analog-to-digital converters that offer a versatile range of
+  specifications. They integrate an analog front end suitable for processing
+  fully differential/single-ended and bipolar voltage inputs.
+
   Datasheets for supported chips:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/AD4111.pdf
+    https://www.analog.com/media/en/technical-documentation/data-sheets/AD4112.pdf
+    https://www.analog.com/media/en/technical-documentation/data-sheets/AD4114.pdf
+    https://www.analog.com/media/en/technical-documentation/data-sheets/AD4115.pdf
+    https://www.analog.com/media/en/technical-documentation/data-sheets/AD4116.pdf
     https://www.analog.com/media/en/technical-documentation/data-sheets/AD7172-2.pdf
     https://www.analog.com/media/en/technical-documentation/data-sheets/AD7172-4.pdf
     https://www.analog.com/media/en/technical-documentation/data-sheets/AD7173-8.pdf
@@ -31,6 +42,11 @@ description: |
 properties:
   compatible:
     enum:
+      - adi,ad4111
+      - adi,ad4112
+      - adi,ad4114
+      - adi,ad4115
+      - adi,ad4116
       - adi,ad7172-2
       - adi,ad7172-4
       - adi,ad7173-8
@@ -129,10 +145,56 @@ patternProperties:
         maximum: 15
 
       diff-channels:
+        description: |
+          This property is used for defining the inputs of a differential
+          voltage channel. The first value is the positive input and the second
+          value is the negative input of the channel.
+
+          Family AD411x supports a dedicated VINCOM voltage input.
+          To select it set the second channel to 16.
+            (VIN2, VINCOM) -> diff-channels = <2 16>
+
+          There are special values that can be selected besides the voltage
+          analog inputs:
+            21: REF+
+            22: REF−
+
+          Supported only by AD7172-2, AD7172-4, AD7175-2, AD7175-8, AD7177-2,
+          must be paired together and can be used to monitor the power supply
+          of the ADC:
+            19: ((AVDD1 − AVSS)/5)+
+            20: ((AVDD1 − AVSS)/5)−
+
         items:
           minimum: 0
           maximum: 31
 
+      single-channel:
+        description: |
+          This property is used for defining a current channel or the positive
+          input of a voltage channel (single-ended or pseudo-differential).
+
+          Models AD4111 and AD4112 support current channels.
+            Example: (IIN2+, IIN2−) -> single-channel = <2>
+          To correctly configure a current channel set the "adi,current-channel"
+          property to true.
+
+          To configure a single-ended/pseudo-differential channel set the
+          "common-mode-channel" property to the desired negative voltage input.
+
+          When used as a voltage channel, special inputs are valid as well.
+        minimum: 0
+        maximum: 31
+
+      common-mode-channel:
+        description:
+          This property is used for defining the negative input of a
+          single-ended or pseudo-differential voltage channel.
+
+          Special inputs are valid as well.
+        minimum: 0
+        maximum: 31
+
       adi,reference-select:
         description: |
           Select the reference source to use when converting on
@@ -154,9 +216,31 @@ patternProperties:
           - avdd
         default: refout-avss
 
+      adi,current-channel:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: |
+          Signal that the selected inputs are current channels.
+          Only available on AD4111 and AD4112.
+
     required:
       - reg
-      - diff-channels
+
+    allOf:
+      - oneOf:
+          - required: [single-channel]
+            properties:
+              diff-channels: false
+          - required: [diff-channels]
+            properties:
+              single-channel: false
+              adi,current-channel: false
+              common-mode-channel: false
+
+      - if:
+          required: [common-mode-channel]
+        then:
+          properties:
+            adi,current-channel: false
 
 required:
   - compatible
@@ -166,7 +250,6 @@ allOf:
   - $ref: /schemas/spi/spi-peripheral-props.yaml#
 
   # Only ad7172-4, ad7173-8 and ad7175-8 support vref2
-  # Other models have [0-3] channel registers
   - if:
       properties:
         compatible:
@@ -187,6 +270,37 @@ allOf:
                 - vref
                 - refout-avss
                 - avdd
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad4114
+              - adi,ad4115
+              - adi,ad4116
+              - adi,ad7173-8
+              - adi,ad7175-8
+    then:
+      patternProperties:
+        "^channel@[0-9a-f]$":
+          properties:
+            reg:
+              maximum: 15
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7172-2
+              - adi,ad7175-2
+              - adi,ad7176-2
+              - adi,ad7177-2
+    then:
+      patternProperties:
+        "^channel@[0-9a-f]$":
+          properties:
             reg:
               maximum: 3
 
@@ -210,6 +324,34 @@ allOf:
           required:
             - adi,reference-select
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad4111
+              - adi,ad4112
+              - adi,ad4114
+              - adi,ad4115
+              - adi,ad4116
+    then:
+      properties:
+        avdd2-supply: false
+
+  - if:
+      properties:
+        compatible:
+          not:
+            contains:
+              enum:
+                - adi,ad4111
+                - adi,ad4112
+    then:
+      patternProperties:
+        "^channel@[0-9a-f]$":
+          properties:
+            adi,current-channel: false
+
   - if:
       anyOf:
         - required: [clock-names]
@@ -221,6 +363,7 @@ allOf:
 unevaluatedProperties: false
 
 examples:
+  # Example AD7173-8 with external reference connected to REF+/REF-:
   - |
     #include <dt-bindings/gpio/gpio.h>
     #include <dt-bindings/interrupt-controller/irq.h>
@@ -277,3 +420,50 @@ examples:
         };
       };
     };
+
+  # Example AD4111 with current channel and single-ended channel:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+       adc@0 {
+        compatible = "adi,ad4111";
+        reg = <0>;
+
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
+        interrupt-names = "rdy";
+        interrupt-parent = <&gpio>;
+        spi-max-frequency = <5000000>;
+        gpio-controller;
+        #gpio-cells = <2>;
+        #clock-cells = <0>;
+
+        channel@0 {
+          reg = <0>;
+          bipolar;
+          diff-channels = <4 5>;
+        };
+
+        // Single ended channel VIN2/VINCOM
+        channel@1 {
+          reg = <1>;
+          bipolar;
+          single-channel = <2>;
+          common-mode-channel = <16>;
+        };
+
+        // Current channel IN2+/IN2-
+        channel@2 {
+          reg = <2>;
+          single-channel = <2>;
+          adi,current-channel;
+        };
+      };
+    };