Re: [PATCH v2 4/8] dt-bindings: iio: dfsdm: move to backend framework

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Hi Rob,

On 6/28/24 23:35, Rob Herring wrote:
On Tue, Jun 25, 2024 at 05:07:12PM +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   Properties superseded by generic properties: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: becomes st,adc-channel-type
     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@xxxxxxxxxxx>
---
  .../bindings/iio/adc/st,stm32-dfsdm-adc.yaml  | 157 +++++++++++++++++-
  1 file changed, 151 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..1802120b16b0 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 ]
          $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+        deprecated: true
st,adc-alt-channel:
          description:
@@ -147,6 +157,7 @@ patternProperties:
            If not set, channel n is connected to SPI input n.
            If set, channel n is connected to SPI input n + 1.
          type: boolean
+        deprecated: true
st,filter0-sync:
          description:
@@ -165,11 +176,64 @@ patternProperties:
        - compatible
        - reg
        - interrupts
-      - st,adc-channels
-      - st,adc-channel-names
        - st,filter-order
        - "#io-channel-cells"
+ patternProperties:
+      "^channel@([0-9]|1[0-9])$":

Unit-addresses are normally hex. And according to reg below, the max
value is 8.


Right. The maximum number of serial interfaces is 8.
So, the pattern can be reduced to "^channel@([0-7])$":

+        type: object
+        $ref: adc.yaml
+        description: Represents the external channels which are connected to the DFSDM.
+
+        properties:
+          reg:
+            items:
+              minimum: 0
+              maximum: 8

More than 1 reg entry valid? Either way, you need maxItems. Or you can
just drop 'items'


Added "maxItems: 1" and dropped items.

+
+          label:
+            description:
+              Unique name to identify which channel this is.
+
+          st,adc-channel-type:
+            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:

'items' is for arrays, but...


Removed items

+              enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
+            $ref: /schemas/types.yaml#/definitions/string

not an 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:

ditto


Done

+              enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
+            $ref: /schemas/types.yaml#/definitions/string
+
+          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:
+              Used to pipe external sigma delta modulator or internal ADC backend to DFSDM channel.

How many entries (maxItems)?

+
+        required:
+          - reg
+
+        additionalProperties: false

Put this next to the $ref for the node. And switch to
unevaluatedProperties and drop 'label' from here.


Done

+
      allOf:
        - if:
            properties:
@@ -199,9 +263,19 @@ 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

Don't think this is needed here. If channel node is present, the
io-backends should always be required, right? Then this can go under the
node schema.


The io-backends property is required only when we use st,stm32-dfsdm-adc compatible. In other words, when we are in an analog use case. In this case the channel is a consumer of a backend (typically a sd modulator) In an audio use case (compatible st,stm32-dfsdm-dmic) the backend is not required.

BRs
Olivier

Rob






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