Re: [RFC v2 03/11] dt-bindings: iio: stm32-dfsdm-adc: add scaling support

[Olivier MOYSAN <olivier.moysan@xxxxxxxxxxx>]

Hi Rob,

On 8/11/23 19:10, Rob Herring wrote:
> On Thu, Jul 27, 2023 at 05:03:14PM +0200, Olivier Moysan wrote:
> > Add scaling support to STM32 DFSDM.
> >
> > This introduces the following changes:
>
> Why?

This RFC is an attempt to support scaling through a change in DFSDM 
topology.

These changes have some impacts on DFSDM and sd modulator bindings.
To keep things simple in this RFC, I skipped legacy support, to put the 
emphasis on the new bindings proposal.
There are two changes here: adoption of the generic IIO bindings and new 
"io-backends" property. This needs to be put in two separate patches at 
the end, I think (as already done for driver patches)

Anyway, the current bindings would become deprecated with these changes. 
I still have to consider how to support these legacy bindings for next 
step, However.

BRs
Olivier

> > - Add ADC generic channel binding and remove support of deprecated
> > channel bindings.
>
> When was it deprecated?
>
> > - DFSDM is now implemented as a channel provider, so remove io-channels
> > properties.
> > - Add iio-backend property to connect DFSDM to an SD modulator.
>
> io-backends
>
> All sorts of ABI issues with this change. Please explain why you don't
> care.
>
> > Signed-off-by: Olivier Moysan <olivier.moysan@xxxxxxxxxxx>
> > ---
> >   .../bindings/iio/adc/st,stm32-dfsdm-adc.yaml  | 189 ++++++------------
> >   1 file changed, 63 insertions(+), 126 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 1970503389aa..128545cedc7f 100644
> > --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
> > +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
> > @@ -85,22 +85,14 @@ patternProperties:
> >           description: Specifies the DFSDM filter instance used.
> >           maxItems: 1
> >   
> > -      interrupts:
> > -        maxItems: 1
> > +      '#address-cells':
> > +        const: 1
> >   
> > -      st,adc-channels:
> > -        description: |
> > -          List of single-ended channels muxed for this ADC.
> > -          On stm32h7 and stm32mp1:
> > -          - For st,stm32-dfsdm-adc: up to 8 channels numbered from 0 to 7.
> > -          - For st,stm32-dfsdm-dmic: 1 channel numbered from 0 to 7.
> > -        $ref: /schemas/types.yaml#/definitions/uint32-array
> > -        items:
> > -          minimum: 0
> > -          maximum: 7
> > +      '#size-cells':
> > +        const: 0
> >   
> > -      st,adc-channel-names:
> > -        description: List of single-ended channel names.
> > +      interrupts:
> > +        maxItems: 1
> >   
> >         st,filter-order:
> >           description: |
> > @@ -111,39 +103,6 @@ patternProperties:
> >           $ref: /schemas/types.yaml#/definitions/uint32
> >           maximum: 5
> >   
> > -      "#io-channel-cells":
> > -        const: 1
> > -
> > -      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
> > -
> > -      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 ]
> > -        $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> > -
> > -      st,adc-alt-channel:
> > -        description:
> > -          Must be defined if two sigma delta modulators are
> > -          connected on same SPI input.
> > -          If not set, channel n is connected to SPI input n.
> > -          If set, channel n is connected to SPI input n + 1.
> > -        type: boolean
> > -
> >         st,filter0-sync:
> >           description:
> >             Set to 1 to synchronize with DFSDM filter instance 0.
> > @@ -157,14 +116,68 @@ patternProperties:
> >           items:
> >             - const: rx
> >   
> > +    patternProperties:
> > +      "^channel@([0-9]|1[0-9])$":
> > +        type: object
> > +        $ref: "adc.yaml"
> > +        description: Represents the external channels which are connected to the DFSDM.
> > +
> > +        properties:
> > +          reg:
> > +            items:
> > +              minimum: 0
> > +              maximum: 19
> > +
> > +          label:
> > +            description: |
> > +              Unique name to identify channel.
> > +
> > +          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
> > +
> > +          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
> > +
> > +          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: |
> > +              phandle to an external sigma delta modulator or internal ADC output.
> > +            $ref: /schemas/types.yaml#/definitions/phandle
> > +
> > +        required:
> > +          - reg
> > +          - io-backends
> > +
> > +        additionalProperties: false
> > +
> >       required:
> >         - compatible
> >         - reg
> >         - interrupts
> > -      - st,adc-channels
> > -      - st,adc-channel-names
> >         - st,filter-order
> > -      - "#io-channel-cells"
> >   
> >       allOf:
> >         - if:
> > @@ -175,14 +188,6 @@ patternProperties:
> >   
> >           then:
> >             properties:
> > -            st,adc-channels:
> > -              minItems: 1
> > -              maxItems: 8
> > -
> > -            st,adc-channel-names:
> > -              minItems: 1
> > -              maxItems: 8
> > -
> >               st,adc-channel-types:
> >                 minItems: 1
> >                 maxItems: 8
> > @@ -191,14 +196,6 @@ patternProperties:
> >                 minItems: 1
> >                 maxItems: 8
> >   
> > -            io-channels:
> > -              description:
> > -                From common IIO binding. Used to pipe external sigma delta
> > -                modulator or internal ADC output to DFSDM channel.
> > -
> > -          required:
> > -            - io-channels
> > -
> >         - if:
> >             properties:
> >               compatible:
> > @@ -207,12 +204,6 @@ patternProperties:
> >   
> >           then:
> >             properties:
> > -            st,adc-channels:
> > -              maxItems: 1
> > -
> > -            st,adc-channel-names:
> > -              maxItems: 1
> > -
> >               st,adc-channel-types:
> >                 maxItems: 1
> >   
> > @@ -237,15 +228,9 @@ patternProperties:
> >                   "#sound-dai-cells":
> >                     const: 0
> >   
> > -                io-channels:
> > -                  description:
> > -                    From common IIO binding. Used to pipe external sigma delta
> > -                    modulator or internal ADC output to DFSDM channel.
> > -
> >                 required:
> >                   - compatible
> >                   - "#sound-dai-cells"
> > -                - io-channels
> >   
> >   allOf:
> >     - if:
> > @@ -278,52 +263,4 @@ allOf:
> >                   minimum: 0
> >                   maximum: 5
> >   
> > -examples:
> > -  - |
> > -    #include <dt-bindings/interrupt-controller/arm-gic.h>
> > -    #include <dt-bindings/clock/stm32mp1-clks.h>
> > -    dfsdm: dfsdm@4400d000 {
> > -      compatible = "st,stm32mp1-dfsdm";
> > -      reg = <0x4400d000 0x800>;
> > -      clocks = <&rcc DFSDM_K>, <&rcc ADFSDM_K>;
> > -      clock-names = "dfsdm", "audio";
> > -      #address-cells = <1>;
> > -      #size-cells = <0>;
> > -
> > -      dfsdm0: filter@0 {
> > -        compatible = "st,stm32-dfsdm-dmic";
> > -        reg = <0>;
> > -        interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
> > -        dmas = <&dmamux1 101 0x400 0x01>;
> > -        dma-names = "rx";
> > -        #io-channel-cells = <1>;
> > -        st,adc-channels = <1>;
> > -        st,adc-channel-names = "dmic0";
> > -        st,adc-channel-types = "SPI_R";
> > -        st,adc-channel-clk-src = "CLKOUT";
> > -        st,filter-order = <5>;
> > -
> > -        asoc_pdm0: dfsdm-dai {
> > -          compatible = "st,stm32h7-dfsdm-dai";
> > -          #sound-dai-cells = <0>;
> > -          io-channels = <&dfsdm0 0>;
> > -        };
> > -      };
> > -
> > -      dfsdm_pdm1: filter@1 {
> > -        compatible = "st,stm32-dfsdm-adc";
> > -        reg = <1>;
> > -        interrupts = <GIC_SPI 111 IRQ_TYPE_LEVEL_HIGH>;
> > -        dmas = <&dmamux1 102 0x400 0x01>;
> > -        dma-names = "rx";
> > -        #io-channel-cells = <1>;
> > -        st,adc-channels = <2 3>;
> > -        st,adc-channel-names = "in2", "in3";
> > -        st,adc-channel-types = "SPI_R", "SPI_R";
> > -        st,adc-channel-clk-src = "CLKOUT_F", "CLKOUT_F";
> > -        io-channels = <&sd_adc2 &sd_adc3>;
> > -        st,filter-order = <1>;
> > -      };
> > -    };
> > -
> >   ...
> > --
> > 2.25.1