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

title: IIO Common Properties for ADC Channels

maintainers:
  - Jonathan Cameron <jic23@kernel.org>

description:
  A few properties are defined in a common way ADC channels.

properties:
  $nodename:
    pattern: "^channel(@[0-9a-f]+)?$"
    description:
      A channel index should match reg.

  reg:
    maxItems: 1

  label:
    description: Unique name to identify which channel this is.

  bipolar:
    $ref: /schemas/types.yaml#/definitions/flag
    description: If provided, the channel is to be used in bipolar mode.

  diff-channels:
    $ref: /schemas/types.yaml#/definitions/uint32-array
    maxItems: 2
    minItems: 2
    description:
      Many ADCs have dual Muxes to allow different input pins to be routed
      to both the positive and negative inputs of a differential ADC.
      The first value specifies the positive input pin, the second
      specifies the negative input pin.
      There are also some ADCs, where the differential channel has dedicated
      positive and negative inputs which can be used to measure differential
      voltage levels. For those setups, this property can be configured with
      the 'reg' property for both inputs (i.e. diff-channels = <reg reg>).

  single-channel:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      When devices combine single-ended and differential channels, allow the
      channel for a single element to be specified, independent of reg (as for
      differential channels). If this and diff-channels are not present reg
      shall be used instead.

  common-mode-channel:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      Some ADCs have differential input pins that can be used to measure
      single-ended or pseudo-differential inputs. This property can be used
      in addition to single-channel to signal software that this channel is
      not differential but still specify two inputs.

      The input pair is specified by setting single-channel to the positive
      input pin and common-mode-channel to the negative pin.

  settling-time-us:
    description:
      Time between enabling the channel and first stable readings.

  oversampling-ratio:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      Oversampling is used as replacement of or addition to the low-pass filter.
      In some cases, the desired filtering characteristics are a function the
      device design and can interact with other characteristics such as
      settling time.

  reference-sources:
    $ref: /schemas/types.yaml#/definitions/string-array
    description:
      Indicates the voltage reference source or sources for this channel. Some
      ADCs usually allow choosing between internal reference sources or a pair
      of external pins.

  input-chopping:
    type: boolean
    description:
      If set, the positive and negative input channels are swapped on every
      other conversion to reduce offset error. This generally comes at the
      expense of added settling time between conversions, so should be omitted
      on systems with high-frequency signals or high data rate requirements.

  excitation-channels:
    $ref: /schemas/types.yaml#/definitions/uint32-array
    description:
      Excitation current sources provide current to resistive temperature
      devices (RTDs), thermistors, diodes and other resistive sensors that
      require constant current biasing.

      This array describes the mux configuration of the excitation current
      sources. The values correspond to pins similar to the diff-channels and
      single-channel properties.

  excitation-current-nanoamp:
    description:
      Excitation current sources provide current to resistive temperature
      devices (RTDs), thermistors, diodes and other resistive sensors that
      require constant current biasing.

      This array describes the current configuration of the excitation current
      sources. The index in the array corresponds to the same index in the
      excitation-channels array.

  burn-out-current-nanoamp:
    description:
      Burn-out current sources provide current to the channel's input pins for
      open-circuit or short-circuit detection.

anyOf:
  - oneOf:
      - required:
          - reg
          - diff-channels
      - required:
          - reg
          - single-channel
  - required:
      - reg

additionalProperties: true