example-schema.yaml

# SPDX-License-Identifier: BSD-2-Clause
# Copyright 2018 Linaro Ltd.
%YAML 1.2
---
# All the top-level keys are standard json-schema keywords except for
# 'maintainers' and 'select'

# $id is a unique idenifier based on the filename
$id: http://devicetree.org/schemas/example-schema.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: An example schema annotated with jsonschema details

maintainers:
  - Rob Herring <robh@kernel.org>

description: |
  A more detailed multi-line description of the binding.

  Details about the hardware device and any links to datasheets can go here.

  The end of the description is marked by indentation less than the first line
  in the description.

select: false
  # 'select' is a schema applied to a DT node to determine if this binding
  # schema should be applied to the node. It is optional and by default the
  # possible compatible strings are extracted and used to match.

properties:
  # A dictionary of DT properties for this binding schema
  compatible:
    # More complicated schema can use oneOf (XOR), anyOf (OR), or allOf (AND)
    # to handle different conditions.
    # In this case, it's needed to handle a variable number of values as there
    # isn't another way to express a constraint of the last string value.
    # The boolean schema must be a list of schemas.
    oneOf:
      - items:
          # items is a list of possible values for the property. The number of
          # values is determined by the number of elements in the list.
          # Order in lists is significant, order in dicts is not
          # Must be one of the 1st enums followed by the 2nd enum
          #
          # Each element in items should be 'enum' or 'const'
          - enum:
              - vendor,soc4-ip
              - vendor,soc3-ip
              - vendor,soc2-ip
          - enum:
              - vendor,soc1-ip
        # additionalItems being false is implied
        # minItems/maxItems equal to 2 is implied
      - items:
          # 'const' is just a special case of an enum with a single possible value
          - const: vendor,soc1-ip

  reg:
    # The description of each element defines the order and implicitly defines
    # the number of reg entries
    items:
      - description: core registers
      - description: aux registers
    # minItems/maxItems equal to 2 is implied

  reg-names:
    # The core schema enforces this is a string array
    items:
      - const: core
      - const: aux

  clocks:
    # Only a single entry, so just need to set the max number of items.
    maxItems: 1

  clock-names:
    items:
      - const: bus

  interrupts:
    # Either 1 or 2 interrupts can be present
    minItems: 1
    maxItems: 2
    items:
      - description: tx or combined interrupt
      - description: rx interrupt

    description: |
      A variable number of interrupts warrants a description of what conditions
      affect the number of interrupts. Otherwise, descriptions on standard
      properties are not necessary.

  interrupt-names:
    # minItems must be specified here because the default would be 2
    minItems: 1
    items:
      - const: "tx irq"
      - const: "rx irq"

  # Property names starting with '#' must be quoted
  '#interrupt-cells':
    # A simple case where the value must always be '2'.
    # The core schema handles that this must be a single integer.
    const: 2

  interrupt-controller: {}
    # The core checks this is a boolean, so just have to list it here to be
    # valid for this binding.

  clock-frequency:
    # The type is set in the core schema. Per device schema only need to set
    # constraints on the possible values.
    minimum: 100
    maximum: 400000
    # The value that should be used if the property is not present
    default: 200

  foo-gpios:
    maxItems: 1
    description: A connection of the 'foo' gpio line.

  vendor,int-property:
    description: Vendor specific properties must have a description
    type: integer # A type is also required
    enum: [2, 4, 6, 8, 10]

  vendor,bool-property:
    description: Vendor specific properties must have a description
    type: boolean

required:
  - compatible
  - reg
  - interrupts
  - interrupt-controller

examples:
  - |
    /{
          compatible = "vendor,soc4-ip", "vendor,soc1-ip";
          reg = <0x1000 0x80>,
                <0x3000 0x80>;
          reg-names = "core", "aux";
          interrupts = <10>;
          interrupt-controller;
    };