linux-kernel - Re: [PATCH v2 2/9] dt-bindings: iio: dac: adi-axi-adc: Add ad7606 variant

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Message-ID: <9ff2ba8c-fdb6-4792-905a-71ca2ddc58b9@baylibre.com>
Date: Wed, 11 Dec 2024 16:01:49 -0600
From: David Lechner <dlechner@...libre.com>
To: Guillaume Stols <gstols@...libre.com>,
 Lars-Peter Clausen <lars@...afoo.de>,
 Michael Hennerich <Michael.Hennerich@...log.com>,
 Jonathan Cameron <jic23@...nel.org>, Nuno Sa <nuno.sa@...log.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, jstephan@...libre.com, aardelean@...libre.com,
 adureghello@...libre.com
Subject: Re: [PATCH v2 2/9] dt-bindings: iio: dac: adi-axi-adc: Add ad7606
 variant

On 12/10/24 4:46 AM, Guillaume Stols wrote:
> A new compatible is added to reflect the specialized version of the HDL.
> We use the parallel interface to write the ADC's registers, and
> accessing this interface requires to use
> ADI_AXI_REG_CONFIG_RD,ADI_AXI_REG_CONFIG_WR and ADI_AXI_REG_CONFIG_CTRL
> in a custom fashion.
> 
> Signed-off-by: Guillaume Stols <gstols@...libre.com>
> ---
>  .../devicetree/bindings/iio/adc/adi,axi-adc.yaml   | 53 ++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml b/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
> index e1f450b80db2..6c3fc44422cc 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
> @@ -17,13 +17,22 @@ description: |
>    interface for the actual ADC, while this IP core will interface
>    to the data-lines of the ADC and handle the streaming of data into
>    memory via DMA.
> +  In some cases, the AXI ADC interface is used to perform specialized
> +  operation to a particular ADC, e.g access the physical bus through
> +  specific registers to write ADC registers.
> +  In this case, we use a different compatible whch indicates the target

s/whch/which/

> +  chip(s)'s name.

s/chip(s)'s/IP core's/

> +  The following IP is currently supported:
> +    -axi_ad7606X: Backend for all the chips from the ad7606 family.

s/axi_ad7606X/AXI AD7606X/ # proper name of the IP core
s/Backend/Specialized version of the IP core/

>  
>    https://wiki.analog.com/resources/fpga/docs/axi_adc_ip
> +  http://analogdevicesinc.github.io/hdl/library/axi_ad7606x/index.html
>  
>  properties:
>    compatible:
>      enum:
>        - adi,axi-adc-10.0.a
> +      - adi,axi-ad7606x
>  
>    reg:
>      maxItems: 1
> @@ -53,6 +62,24 @@ required:
>    - reg
>    - clocks
>  
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: adi,axi-ad7606x
> +    then:
> +      patternProperties:
> +        "^adc@[0-9a-f]+$":
> +          type: object
> +          properties:
> +            reg:
> +              maxItems: 1
> +          additionalProperties: true
> +          required:
> +            - compatible
> +            - reg
> +

The preferred way to compatible-specific bindings is to add
everything at the top level and then disable ones that don't
apply using -if: blocks.

So under the top-level properties:, add

  '#address-cells':
    const: 1
  '#size-cells':
    const 0

and move the patternProperties: to the top level.

Then add not: to the -if: and make the then:

    properties:
      '#address-cells': false
      '#size-cells': false
    patternProperties:
      "^adc@[0-9a-f]+$": false

>  additionalProperties: false
>  
>  examples:
> @@ -65,4 +92,30 @@ examples:
>          clocks = <&axi_clk>;
>          #io-backend-cells = <0>;
>      };
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    axi-adc@...00000 {

Shouldn't we have the label iio_backend: here?

Also, could use a more generic name like "parallel-bus-controller"
instead of "axi-adc".

> +        compatible = "adi,axi-ad7606x";
> +        reg = <0x44a00000 0x10000>;
> +        dmas = <&rx_dma 0>;
> +        dma-names = "rx";
> +        clocks = <&ext_clk>;
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        adi_adc@0 {
> +            compatible = "adi,ad7606b";
> +            reg = <0>;
> +            pwms = <&axi_pwm_gen 0 0>;
> +            pwm-names = "cnvst_n";
> +            avcc-supply = <&adc_vref>;
> +            reset-gpios = <&gpio0 91 GPIO_ACTIVE_HIGH>;
> +            standby-gpios = <&gpio0 90 GPIO_ACTIVE_LOW>;
> +            adi,range-gpios = <&gpio0 89 GPIO_ACTIVE_HIGH>;
> +            adi,oversampling-ratio-gpios = <&gpio0 88 GPIO_ACTIVE_HIGH
> +                            &gpio0 87 GPIO_ACTIVE_HIGH
> +                            &gpio0 86 GPIO_ACTIVE_HIGH>;
> +            io-backends = <&iio_backend>;
> +        };
> +    };
>  ...
>