Re: [PATCH 1/7] dt-bindings: iio: adc: add generic channel binding

On Wed, 8 Sep 2021 17:54:46 +0200 Olivier Moysan olivier.moysan@foss.st.com wrote:

dt-bindings: iio: adc: stm32-adc: ...

Add ADC generic channel binding. This binding should be used as an alternate to legacy channel properties whenever possible. ADC generic channel binding allows to identify supported internal channels through the following reserved label names: "vddcore", "vrefint" and "vbat". This binding also allows to set a different sampling time for each channel.

Signed-off-by: Olivier Moysan olivier.moysan@foss.st.com

Note: The schema here is too permissive as either legacy or generic channels properties are required. These properties are mutually exclusive, however all attempts to describe this constraint are failing. In particular the following schemas and their variants have shown unsucessful.

Given yaml still drives me crazy I'll rely on Rob's expertise for suggestions here.

The new binding text itself looks great to me.

oneOf:

• anyOf:

• required:

  • st,adc-channels

• required:

  • st,adc-diff-channels

• anyOf:

• required:

  • $nodename

• if: patternProperties: "^channel@([0-9]|1[0-9])$": type: object

then: properties: st,adc-channels: false st,adc-diff-channels: false else:

• anyOf:
  • required:
    • st,adc-channels
  • required:
    • st,adc-diff-channels

---

.../bindings/iio/adc/st,stm32-adc.yaml | 100 ++++++++++++++++-- 1 file changed, 93 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml index a58334c3bb76..a1f6cbe144ba 100644 --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml @@ -222,6 +222,12 @@ patternProperties: '#io-channel-cells': const: 1

•  '#address-cells':
  

•    const: 1
  

•  '#size-cells':
  

•    const: 0
  

•  interrupts:
     description: |
       IRQ Line for the ADC instance. Valid values are:
  

@@ -265,7 +271,9 @@ patternProperties: <vinp vinn>, <vinp vinn>,... vinp and vinn are numbered from 0 to 19.

       Note: At least one of "st,adc-channels" or "st,adc-diff-channels" is

•      required. Both properties can be used together. Some channels can be
  

•      required if no adc generic channel is defined. These legacy channel
  

•      properties are exclusive with adc generic channel bindings.
  

•      Both properties can be used together. Some channels can be
       used as single-ended and some other ones as differential (mixed). But
       channels can't be configured both as single-ended and differential.
     $ref: /schemas/types.yaml#/definitions/uint32-matrix
  

@@ -290,6 +298,44 @@ patternProperties: each channel. $ref: /schemas/types.yaml#/definitions/uint32-array

• patternProperties:

•  "^channel@([0-9]|1[0-9])$":
  

•    type: object
  

•    $ref: "adc.yaml"
  

•    description: |
  

•      Represents the external channels which are connected to the ADC.
  

•    properties:
  

•      reg:
  

•        items:
  

•          minimum: 0
  

•          maximum: 19
  

•      label:
  

•        description: |
  

•          Unique name to identify which channel this is.
  

•          Reserved label names "vddcore", "vrefint" and "vbat"
  

•          are used to identify internal channels with matching names.
  

•      diff-channels:
  

•        $ref: /schemas/types.yaml#/definitions/uint32-array
  

•        items:
  

•          minimum: 0
  

•          maximum: 19
  

•      st,min-sample-time-nsecs:
  

•        $ref: /schemas/types.yaml#/definitions/uint32
  

•        description: |
  

•          Minimum sampling time in nanoseconds. Depending on hardware (board)
  

•          e.g. high/low analog input source impedance, fine tune of ADC
  

•          sampling time may be recommended.
  

•    required:
  

•      - reg
  

• dependencies:

•  $nodename: [ '#address-cells', '#size-cells' ]
  

• allOf: - if: properties:

@@ -369,12 +415,6 @@ patternProperties:

 additionalProperties: false

• anyOf:

•  - required:
  

•      - st,adc-channels
  

•  - required:
  

•      - st,adc-diff-channels
  

• required: - compatible - reg

@@ -451,4 +491,50 @@ examples: // other adc child node follow... };

• • |
• // Example 3: with stm32mp157c to setup ADC2 with:
• // - internal channels 13, 14, 15.

•  #include <dt-bindings/interrupt-controller/arm-gic.h>
  

•  #include <dt-bindings/clock/stm32mp1-clks.h>
  

•  adc122: adc@48003000 {
  

•    compatible = "st,stm32mp1-adc-core";
  

•    reg = <0x48003000 0x400>;
  

•    interrupts = <GIC_SPI 18 IRQ_TYPE_LEVEL_HIGH>,
  

•                 <GIC_SPI 90 IRQ_TYPE_LEVEL_HIGH>;
  

•    clocks = <&rcc ADC12>, <&rcc ADC12_K>;
  

•    clock-names = "bus", "adc";
  

•    booster-supply = <&booster>;
  

•    vdd-supply = <&vdd>;
  

•    vdda-supply = <&vdda>;
  

•    vref-supply = <&vref>;
  

•    st,syscfg = <&syscfg>;
  

•    interrupt-controller;
  

•    #interrupt-cells = <1>;
  

•    #address-cells = <1>;
  

•    #size-cells = <0>;
  

•    adc@100 {
  

•      compatible = "st,stm32mp1-adc";
  

•      #io-channel-cells = <1>;
  

•      reg = <0x100>;
  

•      interrupts = <1>;
  

•      #address-cells = <1>;
  

•      #size-cells = <0>;
  

•      channel@13 {
  

•        reg = <13>;
  

•        label = "vrefint";
  

•        st,min-sample-time-nsecs = <9000>;
  

•      };
  

•      channel@14 {
  

•        reg = <14>;
  

•        label = "vddcore";
  

•        st,min-sample-time-nsecs = <9000>;
  

•      };
  

•      channel@15 {
  

•        reg = <15>;
  

•        label = "vbat";
  

•        st,min-sample-time-nsecs = <9000>;
  

•      };
  

•    };
  

•  };
  

...