Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.yaml

# SPDX-License-Identifier: GPL-2.0-only
%YAML 1.2
---
$id: http://devicetree.org/schemas/iio/adc/qcom,spmi-vadc.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Qualcomm's SPMI PMIC ADC

maintainers:
  - Andy Gross <agross@kernel.org>
  - Bjorn Andersson <bjorn.andersson@linaro.org>

description: |
  SPMI PMIC voltage ADC (VADC) provides interface to clients to read
  voltage. The VADC is a 15-bit sigma-delta ADC.
  SPMI PMIC5/PMIC7 voltage ADC (ADC) provides interface to clients to read
  voltage. The VADC is a 16-bit sigma-delta ADC.

properties:
  compatible:
    oneOf:
      - items:
          - const: qcom,pms405-adc
          - const: qcom,spmi-adc-rev2

      - items:
          - enum:
              - qcom,spmi-vadc
              - qcom,spmi-adc5
              - qcom,spmi-adc-rev2
              - qcom,spmi-adc7

  reg:
    description: VADC base address in the SPMI PMIC register map
    maxItems: 1

  '#address-cells':
    const: 1

  '#size-cells':
    const: 0

  '#io-channel-cells':
    const: 1

  interrupts:
    maxItems: 1
    description:
      End of conversion interrupt.

required:
  - compatible
  - reg
  - '#address-cells'
  - '#size-cells'
  - '#io-channel-cells'

patternProperties:
  "^.*@[0-9a-f]+$":
    type: object
    description: |
      Represents the external channels which are connected to the ADC.
      For compatible property "qcom,spmi-vadc" following channels, also known as
      reference point channels, are used for result calibration and their channel
      configuration nodes should be defined:
      VADC_REF_625MV and/or VADC_SPARE1(based on PMIC version) VADC_REF_1250MV,
      VADC_GND_REF and VADC_VDD_VADC.

    properties:
      reg:
        description: |
          ADC channel number.
          See include/dt-bindings/iio/qcom,spmi-vadc.h
          For PMIC7 ADC, the channel numbers are specified separately per PMIC
          in the PMIC-specific files in include/dt-bindings/iio/.

      label:
        $ref: /schemas/types.yaml#/definitions/string
        description: |
            ADC input of the platform as seen in the schematics.
            For thermistor inputs connected to generic AMUX or GPIO inputs
            these can vary across platform for the same pins. Hence select
            the platform schematics name for this channel.

      qcom,decimation:
        $ref: /schemas/types.yaml#/definitions/uint32
        description: |
            This parameter is used to decrease ADC sampling rate.
            Quicker measurements can be made by reducing decimation ratio.

      qcom,pre-scaling:
        description: |
            Used for scaling the channel input signal before the signal is
            fed to VADC. The configuration for this node is to know the
            pre-determined ratio and use it for post scaling. It is a pair of
            integers, denoting the numerator and denominator of the fraction by which
            input signal is multiplied. For example, <1 3> indicates the signal is scaled
            down to 1/3 of its value before ADC measurement.
            If property is not found default value depending on chip will be used.
        $ref: /schemas/types.yaml#/definitions/uint32-array
        oneOf:
          - items:
              - const: 1
              - enum: [ 1, 3, 4, 6, 20, 8, 10 ]
          - items:
              - const: 10
              - const: 81

      qcom,ratiometric:
        description: |
            Channel calibration type.
            - For compatible property "qcom,spmi-vadc", if this property is
              specified VADC will use the VDD reference (1.8V) and GND for
              channel calibration. If property is not found, channel will be
              calibrated with 0.625V and 1.25V reference channels, also
              known as absolute calibration.
            - For compatible property "qcom,spmi-adc5", "qcom,spmi-adc7" and
              "qcom,spmi-adc-rev2", if this property is specified VADC will use
              the VDD reference (1.875V) and GND for channel calibration. If
              property is not found, channel will be calibrated with 0V and 1.25V
              reference channels, also known as absolute calibration.
        type: boolean

      qcom,hw-settle-time:
        $ref: /schemas/types.yaml#/definitions/uint32
        description: |
            Time between AMUX getting configured and the ADC starting
            conversion. The 'hw_settle_time' is an index used from valid values
            and programmed in hardware to achieve the hardware settling delay.

      qcom,avg-samples:
        $ref: /schemas/types.yaml#/definitions/uint32
        description: |
            Number of samples to be used for measurement.
            Averaging provides the option to obtain a single measurement
            from the ADC that is an average of multiple samples. The value
            selected is 2^(value).

    required:
      - reg

allOf:
  - if:
      properties:
        compatible:
          contains:
            const: qcom,spmi-vadc

    then:
      patternProperties:
        "^.*@[0-9a-f]+$":
          properties:
            qcom,decimation:
              enum: [ 512, 1024, 2048, 4096 ]
              default: 512

            qcom,hw-settle-time:
              enum: [ 0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1, 2,
                      4, 6, 8, 10 ]
              default: 0

            qcom,avg-samples:
              enum: [ 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 ]
              default: 1

  - if:
      properties:
        compatible:
          contains:
            const: qcom,spmi-adc-rev2

    then:
      patternProperties:
        "^.*@[0-9a-f]+$":
          properties:
            qcom,decimation:
              enum: [ 256, 512, 1024 ]
              default: 1024

            qcom,hw-settle-time:
              enum: [ 0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1, 2,
                      4, 6, 8, 10 ]
              default: 0

            qcom,avg-samples:
              enum: [ 1, 2, 4, 8, 16 ]
              default: 1

  - if:
      properties:
        compatible:
          contains:
            const: qcom,spmi-adc5

    then:
      patternProperties:
        "^.*@[0-9a-f]+$":
          properties:
            qcom,decimation:
              enum: [ 250, 420, 840 ]
              default: 840

            qcom,hw-settle-time:
              enum: [ 15, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1, 2,
                      4, 6, 8, 10, 16, 32, 64, 128 ]
              default: 15

            qcom,avg-samples:
              enum: [ 1, 2, 4, 8, 16 ]
              default: 1

  - if:
      properties:
        compatible:
          contains:
            const: qcom,spmi-adc7

    then:
      patternProperties:
        "^.*@[0-9a-f]+$":
          properties:
            qcom,decimation:
              enum: [ 85, 340, 1360 ]
              default: 1360

            qcom,hw-settle-time:
              enum: [ 15, 100, 200, 300, 400, 500, 600, 700, 1000, 2000, 4000,
                      8000, 16000, 32000, 64000, 128000 ]
              default: 15

            qcom,avg-samples:
              enum: [ 1, 2, 4, 8, 16 ]
              default: 1

examples:
  - |
    spmi_bus {
      #address-cells = <1>;
      #size-cells = <0>;
      /* VADC node */
      pmic_vadc: adc@3100 {
        compatible = "qcom,spmi-vadc";
        reg = <0x3100>;
        interrupts = <0x0 0x31 0x0 0x1>;
        #address-cells = <1>;
        #size-cells = <0>;
        #io-channel-cells = <1>;
        io-channel-ranges;

        /* Channel node */
        adc-chan@39 {
          reg = <0x39>;
          qcom,decimation = <512>;
          qcom,ratiometric;
          qcom,hw-settle-time = <200>;
          qcom,avg-samples = <1>;
          qcom,pre-scaling = <1 3>;
        };

        adc-chan@9 {
          reg = <0x9>;
        };

        adc-chan@a {
          reg = <0xa>;
        };

        adc-chan@e {
          reg = <0xe>;
        };

        adc-chan@f {
          reg = <0xf>;
        };
      };
    };