linux-kernel - Re: [PATCH v2 7/8] dt-bindings: iio: adc: adi,ad4030: Add ADAQ4216 and ADAQ4224

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Message-ID: <20250919-unsure-mounted-0fc49ce72216@spud>
Date: Fri, 19 Sep 2025 18:36:12 +0100
From: Conor Dooley <conor@...nel.org>
To: Marcelo Schmitt <marcelo.schmitt@...log.com>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org, jic23@...nel.org,
	michael.hennerich@...log.com, nuno.sa@...log.com,
	eblanc@...libre.com, dlechner@...libre.com, andy@...nel.org,
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
	corbet@....net, marcelo.schmitt1@...il.com
Subject: Re: [PATCH v2 7/8] dt-bindings: iio: adc: adi,ad4030: Add ADAQ4216
 and ADAQ4224

On Thu, Sep 18, 2025 at 02:39:29PM -0300, Marcelo Schmitt wrote:
> ADAQ4216 and ADAQ4224 are similar to AD4030 except that ADAQ devices have a
> PGA (programmable gain amplifier) that scales the input signal prior to it
> reaching the ADC inputs. The PGA is controlled through a couple of pins (A0
> and A1) that set one of four possible signal gain configurations.
> 
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@...log.com>
> ---
> Change log v1 -> v2
> - Use pattern to specify devices that require gain related properties.
> - Disallow gain related properties for devices that don't come with embedded PGA.
> - Documented VDDH and VDD_FDA supplies for ADAQ4216 and ADAQ4224.
> - Updated PGA gain constants.
> 
>  .../bindings/iio/adc/adi,ad4030.yaml          | 65 +++++++++++++++++--
>  1 file changed, 60 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml
> index 564b6f67a96e..bd43c617ae11 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml
> @@ -19,6 +19,8 @@ description: |
>    * https://www.analog.com/media/en/technical-documentation/data-sheets/ad4030-24-4032-24.pdf
>    * https://www.analog.com/media/en/technical-documentation/data-sheets/ad4630-24_ad4632-24.pdf
>    * https://www.analog.com/media/en/technical-documentation/data-sheets/ad4630-16-4632-16.pdf
> +  * https://www.analog.com/media/en/technical-documentation/data-sheets/adaq4216.pdf
> +  * https://www.analog.com/media/en/technical-documentation/data-sheets/adaq4224.pdf
>  
>  $ref: /schemas/spi/spi-peripheral-props.yaml#
>  
> @@ -31,6 +33,8 @@ properties:
>        - adi,ad4630-24
>        - adi,ad4632-16
>        - adi,ad4632-24
> +      - adi,adaq4216
> +      - adi,adaq4224
>  
>    reg:
>      maxItems: 1
> @@ -54,6 +58,14 @@ properties:
>      description:
>        Internal buffered Reference. Used when ref-supply is not connected.
>  
> +  vddh-supply:
> +    description:
> +      PGIA Positive Power Supply.
> +
> +  vdd-fda-supply:
> +    description:
> +      FDA Positive Power Supply.
> +
>    cnv-gpios:
>      description:
>        The Convert Input (CNV). It initiates the sampling conversions.
> @@ -64,6 +76,27 @@ properties:
>        The Reset Input (/RST). Used for asynchronous device reset.
>      maxItems: 1
>  
> +  pga-gpios:
> +    description:
> +      A0 and A1 pins for gain selection. For devices that have PGA configuration
> +      input pins, pga-gpios should be defined if adi,gain-milli is absent.
> +    minItems: 2
> +    maxItems: 2
> +
> +  adi,pga-value:
> +    $ref: /schemas/types.yaml#/definitions/uint32

How come this is "value" rather than "gain"?

> +    description: |
> +      Should be present if PGA control inputs are pin-strapped. The values
> +      specify the gain per mille. For example, 333 means the input signal is
> +      scaled by a 0.333 factor (i.e. attenuated to one third of it's original
> +      magnitude). Possible values:
> +      Gain 333 (A1=0, A0=0)
> +      Gain 555 (A1=0, A0=1)
> +      Gain 2222 (A1=1, A0=0)
> +      Gain 6666 (A1=1, A0=1)
> +      If defined, pga-gpios must be absent.
> +    enum: [333, 555, 2222, 6666]
> +
>    pwms:
>      description: PWM signal connected to the CNV pin.
>      maxItems: 1
> @@ -86,11 +119,33 @@ required:
>    - vio-supply
>    - cnv-gpios
>  
> -oneOf:
> -  - required:
> -      - ref-supply
> -  - required:
> -      - refin-supply
> +allOf:
> +  - oneOf:
> +      - required:
> +          - ref-supply
> +      - required:
> +          - refin-supply
> +  # ADAQ devices require a gain property to indicate how hardware PGA is set
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            pattern: ^adi,adaq
> +    then:
> +      allOf:
> +        - required: [vddh-supply, vdd-fda-supply]
> +          properties:
> +            ref-supply: false
> +        - oneOf:
> +            - required:
> +                - adi,pga-value
> +            - required:
> +                - pga-gpios
> +    else:
> +      properties:
> +        adi,pga-value: false
> +        pga-gpios: false
> +
>  
>  unevaluatedProperties: false
>  
> -- 
> 2.50.1
> 

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