Re: [PATCH v3 04/10] dt-bindings: iio: dac: ad3552r: add io-backend support

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 19 Sep 2024 11:20:00 +0200
Angelo Dureghello <adureghello@baylibre.com> wrote:

> From: Angelo Dureghello <adureghello@baylibre.com>
> 
> There is a version AXI DAC IP block (for FPGAs) that provides
> a physical bus for AD3552R and similar chips, and acts as
> an SPI controller.

Wrap is a bit short. Aim for < 75 chars for patch descriptions.

> 
> For this case, the binding is modified to include some
> additional properties.
> 
> Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
> ---
>  .../devicetree/bindings/iio/dac/adi,ad3552r.yaml   | 42 ++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml b/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
> index 41fe00034742..aca4a41c2633 100644
> --- a/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
> +++ b/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
> @@ -60,6 +60,18 @@ properties:
>      $ref: /schemas/types.yaml#/definitions/uint32
>      enum: [0, 1, 2, 3]
>  
> +  io-backends:
> +    description: The iio backend reference.

Give a description of what the backend does in this case.  I.e. that it is
a qspi DDR backend with ...

> +      An example backend can be found at
> +        https://analogdevicesinc.github.io/hdl/library/axi_ad3552r/index.html
> +    maxItems: 1
> +
> +  adi,synchronous-mode:
> +    description: Enable waiting for external synchronization signal.
> +      Some AXI IP configuration can implement a dual-IP layout, with internal
> +      wirings for streaming synchronization.

I've no idea what a dual-IP layout is.  Can you provide a little more info
here?  What are the two IPs?

> +    type: boolean
> +
>    '#address-cells':
>      const: 1
>  
> @@ -128,6 +140,7 @@ patternProperties:
>            - custom-output-range-config
>  
>  allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
>    - if:
>        properties:
>          compatible:
> @@ -238,4 +251,33 @@ examples:
>              };
>          };
>      };
> +
> +  - |
> +    axi_dac: spi@44a70000 {
> +        compatible = "adi,axi-ad3552r";
> +        reg = <0x44a70000 0x1000>;
> +        dmas = <&dac_tx_dma 0>;
> +        dma-names = "tx";
> +        #io-backend-cells = <0>;
> +        clocks = <&ref_clk>;
> +
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        dac@0 {
> +            compatible = "adi,ad3552r";
> +            reg = <0>;
> +            reset-gpios = <&gpio0 92 0>;
> +            io-backends = <&axi_dac>;
> +            spi-max-frequency = <66000000>;
> +
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            channel@0 {
> +                reg = <0>;
> +                adi,output-range-microvolt = <(-10000000) (10000000)>;
> +            };
> +        };
> +    };
>  ...
>