Re: [PATCH RFC 1/4] dt-bindings: iio: adc: ad7380: add adaq4370-4 and adaq4380-4 compatible parts

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 15 Oct 2024 11:09:06 +0200
Julien Stephan <jstephan@baylibre.com> wrote:

> adaq4370-4 (2MSPS) and adaq4380-4 (4MSPS) are quad-channel precision data
> acquisition signal chain μModule solutions compatible with the ad738x
> family, with the following differences:
> 
> - configurable gain in front of each 4 adc
As per quick review I gave for the driver code, I'm not seeing why
a configurable gain is a DT thing on an ADC vs something that belongs
in userspace control.  I may be missing something though.

It exists for the ad4000 because the control isn't via registers
but via pin straps so we can't control it sensibly from userspace.

Jonathan

> - internal reference is 3V derived from refin-supply (5V)
> - additional supplies
> 
> To configure the gain a new patternProperties is added to describe each
> channel. It is restricted to adaq devices.
> 
> Signed-off-by: Julien Stephan <jstephan@baylibre.com>
> ---
>  .../devicetree/bindings/iio/adc/adi,ad7380.yaml    | 117 +++++++++++++++++++++
>  1 file changed, 117 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
> index 74d82721637c..3007d8e39684 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
> @@ -25,6 +25,8 @@ description: |
>    * https://www.analog.com/en/products/ad7386-4.html
>    * https://www.analog.com/en/products/ad7387-4.html
>    * https://www.analog.com/en/products/ad7388-4.html
> +  * https://www.analog.com/en/products/adaq4370-4.html
> +  * https://www.analog.com/en/products/adaq4380-4.html
>  
>  
>  $ref: /schemas/spi/spi-peripheral-props.yaml#
> @@ -46,6 +48,8 @@ properties:
>        - adi,ad7386-4
>        - adi,ad7387-4
>        - adi,ad7388-4
> +      - adi,adaq4370-4
> +      - adi,adaq4380-4
>  
>    reg:
>      maxItems: 1
> @@ -59,6 +63,9 @@ properties:
>    vlogic-supply: true
>    refio-supply: true
>    refin-supply: true
> +  vs-p-supply: true
> +  vs-n-supply: true
> +  ldo-supply: true
>  
>    aina-supply:
>      description:
> @@ -86,12 +93,43 @@ properties:
>        specify the ALERT interrupt.
>      maxItems: 1
>  
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
>  required:
>    - compatible
>    - reg
>    - vcc-supply
>    - vlogic-supply
>  
> +patternProperties:
> +  "^channel@([0-3])$":
> +    $ref: adc.yaml
> +    type: object
> +
> +    properties:
> +      reg:
> +        description:
> +          The channel number. From 0 to 3 corresponding to channels A,B,C,D
> +        items:
> +          minimum: 0
> +          maximum: 3
> +
> +      adi,gain-milli:
> +        description:
> +          The hardware gain applied to the ADC input (in milli units).
> +          If not present, default to 1000 (no actual gain applied).
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        default: 1000
> +
> +    required:
> +      - reg
> +
> +    additionalProperties: false
> +
>  unevaluatedProperties: false
>  
>  allOf:
> @@ -128,7 +166,21 @@ allOf:
>          ainc-supply: false
>          aind-supply: false
>  
> +  # Using channel to declare gain property only applies to adaq devices
> +  - if:
> +      properties:
> +        compatible:
> +          not:
> +            contains:
> +              enum:
> +                - adi,adaq4370-4
> +                - adi,adaq4380-4
> +    then:
> +      patternProperties:
> +        "^channel@([0-3])$": false
> +
>    # ad7380-4 uses refin-supply as external reference.
> +  # adaq devices use internal reference only, derived from refin-supply
>    # All other chips from ad738x family use refio as optional external reference.
>    # When refio-supply is omitted, internal reference is used.
>    - if:
> @@ -136,6 +188,8 @@ allOf:
>          compatible:
>            enum:
>              - adi,ad7380-4
> +            - adi,adaq4370-4
> +            - adi,adaq4380-4
>      then:
>        properties:
>          refio-supply: false
> @@ -145,6 +199,24 @@ allOf:
>        properties:
>          refin-supply: false
>  
> +  # adaq devices need more supplies
> +  - if:
> +      properties:
> +        compatible:
> +          enum:
> +            - adi,adaq4370-4
> +            - adi,adaq4380-4
> +    then:
> +      required:
> +        - vs-p-supply
> +        - vs-n-supply
> +        - ldo-supply
> +    else:
> +      properties:
> +        vs-p-supply: false
> +        vs-n-supply: false
> +        ldo-supply: false
> +
>  examples:
>    - |
>      #include <dt-bindings/interrupt-controller/irq.h>
> @@ -169,3 +241,48 @@ examples:
>              refio-supply = <&supply_2_5V>;
>          };
>      };
> +
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        adc@0 {
> +            compatible = "adi,adaq4380-4";
> +            reg = <0>;
> +
> +            spi-cpol;
> +            spi-cpha;
> +            spi-max-frequency = <80000000>;
> +
> +            interrupts = <27 IRQ_TYPE_EDGE_FALLING>;
> +            interrupt-parent = <&gpio0>;
> +
> +            vcc-supply = <&supply_3_3V>;
> +            vlogic-supply = <&supply_3_3V>;
> +            refin-supply = <&supply_5V>;
> +            vs-p-supply = <&supply_5V>;
> +            vs-n-supply = <&supply_0V>;
> +            ldo-supply = <&supply_5V>;
> +
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            channel@0 {
> +                reg = <0>;
> +                adi,gain-milli = <300>;
> +            };
> +
> +            channel@2 {
> +                reg = <2>;
> +                adi,gain-milli = <600>;
> +            };
> +
> +            channel@3 {
> +                reg = <3>;
> +                adi,gain-milli = <1000>;
> +            };
> +        };
> +    };
>