Re: [PATCH 4/8] dt-bindings: iio: dfsdm: move to backend framework

[Conor Dooley <conor@kernel.org>]

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On Tue, Jun 18, 2024 at 06:08:30PM +0200, Olivier Moysan wrote:
> Change the DFSDM binding to use the new IIO backend framework,
> along with the adoption of IIO generic channels.
> This binding change allows to add scaling support to the DFSDM.
> 
> Keep the legacy binding as deprecated for backward compatibility.
> 
> The io-backends property is supported only in generic IIO channel
> binding.
> 
> - Channel description with the generic binding (Audio and Analog):
> 
>   Properties supersed by generic properties:
>     st,adc-channels: becomes "reg" property in channel node
>     st,adc-channel-names: becomes "label" property in channel node
>   Properties moved to channel child node:
>     st,adc-channel-types, st,adc-channel-clk-src, st,adc-alt-channel
> 
> - Analog binding:
> 
>   DFSDM filter channel is configured as an IIO backend consumer.
>   Add io-backends property in channel child nodes.
> 
>   DFSDM is no more configured as a channel consumer from SD modulator.
>   Use of io-channels in DFSDM node is deprecated.
> 
> - Audio binding:
> 
>   DFSDM audio DAI is configured as a channel consumer from DFSDM filter.
>   No change compare to legacy.
> 
> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
> ---
>  .../bindings/iio/adc/st,stm32-dfsdm-adc.yaml  | 158 +++++++++++++++++-
>  1 file changed, 152 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
> index c1b1324fa132..dd414bab74c1 100644
> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
> @@ -102,9 +102,11 @@ patternProperties:
>          items:
>            minimum: 0
>            maximum: 7
> +        deprecated: true
>  
>        st,adc-channel-names:
>          description: List of single-ended channel names.
> +        deprecated: true
>  
>        st,filter-order:
>          description: |
> @@ -118,6 +120,12 @@ patternProperties:
>        "#io-channel-cells":
>          const: 1
>  
> +      '#address-cells':
> +        const: 1
> +
> +      '#size-cells':
> +        const: 0
> +
>        st,adc-channel-types:
>          description: |
>            Single-ended channel input type.
> @@ -128,6 +136,7 @@ patternProperties:
>          items:
>            enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
>          $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> +        deprecated: true
>  
>        st,adc-channel-clk-src:
>          description: |
> @@ -139,6 +148,7 @@ patternProperties:
>          items:
>            enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
>          $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> +        deprecated: true
>  
>        st,adc-alt-channel:
>          description:
> @@ -147,6 +157,7 @@ patternProperties:
>            If not set, channel n is connected to SPI input n.
>            If set, channel n is connected to SPI input n + 1.
>          type: boolean
> +        deprecated: true
>  
>        st,filter0-sync:
>          description:
> @@ -165,11 +176,65 @@ patternProperties:
>        - compatible
>        - reg
>        - interrupts
> -      - st,adc-channels
> -      - st,adc-channel-names
>        - st,filter-order
>        - "#io-channel-cells"
>  
> +    patternProperties:
> +      "^channel@([0-9]|1[0-9])$":
> +        type: object
> +        $ref: adc.yaml
> +        description: Represents the external channels which are connected to the DFSDM.
> +
> +        properties:
> +          reg:
> +            items:
> +              minimum: 0
> +              maximum: 8
> +
> +          label:
> +            description:
> +              Unique name to identify which channel this is.
> +
> +          st,adc-channel-types:
> +            description: |
> +              Single-ended channel input type.
> +              - "SPI_R": SPI with data on rising edge (default)
> +              - "SPI_F": SPI with data on falling edge
> +              - "MANCH_R": manchester codec, rising edge = logic 0, falling edge = logic 1
> +              - "MANCH_F": manchester codec, rising edge = logic 1, falling edge = logic 0
> +            items:
> +              enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
> +            $ref: /schemas/types.yaml#/definitions/non-unique-string-array

Why is this an array? And why is the property plural? Can a channel have
more than one type?

> +
> +          st,adc-channel-clk-src:
> +            description: |
> +              Conversion clock source.
> +              - "CLKIN": external SPI clock (CLKIN x)
> +              - "CLKOUT": internal SPI clock (CLKOUT) (default)
> +              - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
> +              - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
> +            items:
> +              enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
> +            $ref: /schemas/types.yaml#/definitions/non-unique-string-array

Ditto here, but s/type/clock source/

Thanks,
Conor.

> +
> +          st,adc-alt-channel:
> +            description:
> +              Must be defined if two sigma delta modulators are
> +              connected on same SPI input.
> +              If not set, channel n is connected to SPI input n.
> +              If set, channel n is connected to SPI input n + 1.
> +            type: boolean
> +
> +          io-backends:
> +            description:
> +              From common IIO binding.

Drop this from the description.

> Used to pipe external sigma delta
> +              modulator or internal ADC backend to DFSDM channel.
> +
> +        required:
> +          - reg
> +
> +        additionalProperties: false
> +
>      allOf:
>        - if:
>            properties:
> @@ -199,9 +264,19 @@ patternProperties:
>                description:
>                  From common IIO binding. Used to pipe external sigma delta
>                  modulator or internal ADC output to DFSDM channel.
> +              deprecated: true
>  
> -          required:
> -            - io-channels
> +          if:
> +            required:
> +              - st,adc-channels
> +          then:
> +            required:
> +              - io-channels
> +
> +          patternProperties:
> +            "^channel@([0-9]|1[0-9])$":
> +              required:
> +                - io-backends

Why is this here, rather than with reg above? Only some channels require
a backend?

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