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+# SPDX-License-Identifier: (GPL-2.0-only OR 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'
+
+# $id is a unique identifier based on the filename. There may or may not be a
+# file present at the URL.
+$id: http://devicetree.org/schemas/example-schema.yaml#
+# $schema is the meta-schema this schema should be validated with.
+$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.
+
+ Literal blocks are marked with the '|' at the beginning. The end is marked by
+ indentation less than the first line of the literal block. Lines also cannot
+ begin with a tab character.
+
+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.
+
+ # In this case, a 'false' schema will never 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 core schema already checks that reg values are numbers, so device
+ # specific schema don't need to do those checks.
+ # 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 (*-names) is a string array
+ items:
+ - const: core
+ - const: aux
+
+ clocks:
+ # Cases that have only a single entry just need to express that with maxItems
+ maxItems: 1
+ description: bus clock. A description is only needed for a single item if
+ there's something unique to add.
+ The items should have a fixed order, so pattern matching names are
+ discouraged.
+
+ 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.
+ The items should have a fixed order, so pattern matching names are
+ discouraged.
+
+ interrupt-names:
+ # minItems must be specified here because the default would be 2
+ minItems: 1
+ maxItems: 2
+ 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: true
+ # 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.
+
+ # *-supply is always a single phandle, so nothing more to define.
+ foo-supply: true
+
+ # Vendor specific properties
+ #
+ # Vendor specific properties have slightly different schema requirements than
+ # common properties. They must have at least a type definition and
+ # 'description'.
+ vendor,int-property:
+ description: Vendor specific properties must have a description
+ $ref: /schemas/types.yaml#/definitions/uint32
+ enum: [2, 4, 6, 8, 10]
+
+ vendor,bool-property:
+ description: Vendor specific properties must have a description. Boolean
+ properties are one case where the json-schema 'type' keyword can be used
+ directly.
+ type: boolean
+
+ vendor,string-array-property:
+ description: Vendor specific properties should reference a type in the
+ core schema.
+ $ref: /schemas/types.yaml#/definitions/string-array
+ items:
+ - enum: [foo, bar]
+ - enum: [baz, boo]
+
+ vendor,property-in-standard-units-microvolt:
+ description: Vendor specific properties having a standard unit suffix
+ don't need a type.
+ enum: [ 100, 200, 300 ]
+
+ child-node:
+ description: Child nodes are just another property from a json-schema
+ perspective.
+ type: object # DT nodes are json objects
+ properties:
+ vendor,a-child-node-property:
+ description: Child node properties have all the same schema
+ requirements.
+ type: boolean
+
+ required:
+ - vendor,a-child-node-property
+
+# Describe the relationship between different properties
+dependencies:
+ # 'vendor,bool-property' is only allowed when 'vendor,string-array-property'
+ # is present
+ vendor,bool-property: [ 'vendor,string-array-property' ]
+ # Expressing 2 properties in both orders means all of the set of properties
+ # must be present or none of them.
+ vendor,string-array-property: [ 'vendor,bool-property' ]
+
+required:
+ - compatible
+ - reg
+ - interrupts
+ - interrupt-controller
+
+# if/then schema can be used to handle conditions on a property affecting
+# another property. A typical case is a specific 'compatible' value changes the
+# constraints on other properties.
+#
+# For multiple 'if' schema, group them under an 'allOf'.
+#
+# If the conditionals become too unweldy, then it may be better to just split
+# the binding into separate schema documents.
+allOf:
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: vendor,soc2-ip
+ then:
+ required:
+ - foo-supply
+ # Altering schema depending on presence of properties is usually done by
+ # dependencies (see above), however some adjustments might require if:
+ - if:
+ required:
+ - vendor,bool-property
+ then:
+ properties:
+ vendor,int-property:
+ enum: [2, 4, 6]
+
+# Ideally, the schema should have this line otherwise any other properties
+# present are allowed. There's a few common properties such as 'status' and
+# 'pinctrl-*' which are added automatically by the tooling.
+#
+# This can't be used in cases where another schema is referenced
+# (i.e. allOf: [{$ref: ...}]).
+# If and only if another schema is referenced and arbitrary children nodes can
+# appear, "unevaluatedProperties: false" could be used. A typical example is
+# an I2C controller where no name pattern matching for children can be added.
+additionalProperties: false
+
+examples:
+ # Examples are now compiled with dtc and validated against the schemas
+ #
+ # Examples have a default #address-cells and #size-cells value of 1. This can
+ # be overridden or an appropriate parent bus node should be shown (such as on
+ # i2c buses).
+ #
+ # Any includes used have to be explicitly included.
+ - |
+ node@1000 {
+ compatible = "vendor,soc4-ip", "vendor,soc1-ip";
+ reg = <0x1000 0x80>,
+ <0x3000 0x80>;
+ reg-names = "core", "aux";
+ interrupts = <10>;
+ interrupt-controller;
+ };