devicetree/bindings/writing-schema.rst

3 Writing Devicetree Bindings in json-schema
6 Devicetree bindings are written using json-schema vocabulary. Schema files are
11 Also see :ref:`example-schema`.
13 Schema Contents
16 Each schema doc is a structured json-schema which is defined by a set of
18 top-level json-schema properties used are:
21   A json-schema unique identifier string. The string must be a valid
22   URI typically containing the binding's filename and path. For DT schema, it must
24   references to other files specified in schema "$ref" properties. A $ref value
27   components of the current schema file's '$id' value. A URL is used even for
30 $schema
31   Indicates the meta-schema the schema file adheres to.
34   A one-line description on the contents of the binding schema.
47   Optional. A json-schema used to match nodes for applying the
48   schema. By default, without 'select', nodes are matched against their possible
57   A set of sub-schema defining all the DT properties for the
58   binding. The exact schema syntax depends on whether properties are known,
65 For more details on properties sections, see 'Property Schema' section.
80 Property Schema
83 The 'properties' section of the schema contains all the DT properties for a
84 binding. Each property contains a set of constraints using json-schema
89 binding schema need to be defined such as how many values are valid or what
92 Vendor-specific properties will typically need more detailed schema. With the
98 boilerplate. The tools process the schema files to produce the final schema for
101 The default for arrays in json-schema is they are variable-sized and allow more
114 Use YAML coding style (two-space indentation). For DTS examples in the schema,
123 The DT schema project must be installed in order to validate the DT schema
124 binding documents and validate DTS files using the DT schema. The DT schema
134 Several executables (dt-doc-validate, dt-mk-schema, dt-validate) will be
142 The DT schema binding documents must be validated using the meta-schema (the
143 schema for the schema) to ensure they are both valid json-schema and valid
144 binding schema. All of the DT binding documents can be validated using the
153 Note that ``dtbs_check`` will skip any binding schema files with errors. It is
155 binding schema files.
161 It is also possible to run checks with a subset of matching schema files by
162 setting the ``DT_SCHEMA_FILES`` variable to a specific schema file or pattern.
171 json-schema Resources
175 `JSON-Schema Specifications <http://json-schema.org/>`_
177 `Using JSON Schema Book <http://usingjsonschema.com/>`_
179 .. _example-schema:
181 Annotated Example Schema
184 Also available as a separate file: :download:`example-schema.yaml`
186 .. literalinclude:: example-schema.yaml