Lines Matching +full:dt +full:- +full:schema
1 .. SPDX-License-Identifier: GPL-2.0
3 Writing Devicetree Bindings in json-schema
6 Devicetree bindings are written using json-schema vocabulary. Schema files are
7 written in a JSON-compatible subset of YAML. YAML is used instead of JSON as it
11 Also see :ref:`example-schema`.
13 Schema Contents
14 ---------------
16 Each schema doc is a structured json-schema which is defined by a set of
17 top-level properties. Generally, there is one binding defined per file. The
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 of the hardware being described in the binding schema.
37 A DT specific property. Contains a list of email address(es)
41 Optional. A multi-line text block containing any detailed
70 multi-line YAML text blocks can be found online:
72 https://yaml-multiline.info/
77 Optional. A json-schema used to match nodes for applying the
78 schema. By default, without 'select', nodes are matched against their possible
79 compatible-string values or node name. Most bindings should not need select.
87 A set of sub-schema defining all the DT properties for the
88 binding. The exact schema syntax depends on whether properties are known,
89 common properties (e.g. 'interrupts') or are binding/vendor-specific
92 A property can also define a child DT node with child properties defined
95 For more details on properties sections, see 'Property Schema' section.
101 A list of DT properties from the 'properties' section that
105 Keywords controlling how schema will validate properties not matched by this
106 schema's 'properties' or 'patternProperties'. Each schema is supposed to
107 have exactly one of these keywords in top-level part, so either
112 Most common case, where no additional schema is referenced or if this
116 Used when this binding references other schema whose all properties
122 'unevaluatedProperties: false'. Typically bus or common-part schemas.
132 Property Schema
133 ---------------
135 The 'properties' section of the schema contains all the DT properties for a
136 binding. Each property contains a set of constraints using json-schema
138 validation of DT files.
141 binding schema need to be defined such as how many values are valid or what
144 Vendor-specific properties will typically need more detailed schema. With the
148 The Devicetree schemas don't exactly match the YAML-encoded DT data produced by
150 boilerplate. The tools process the schema files to produce the final schema for
153 The default for arrays in json-schema is they are variable-sized and allow more
164 ------------
166 Use YAML coding style (two-space indentation). For DTS examples in the schema,
167 preferred is four-space indentation.
170 -------
175 The DT schema project must be installed in order to validate the DT schema
176 binding documents and validate DTS files using the DT schema. The DT schema
184 apt install swig python3-dev
186 Several executables (dt-doc-validate, dt-mk-schema, dt-validate) will be
194 The DT schema binding documents must be validated using the meta-schema (the
195 schema for the schema) to ensure they are both valid json-schema and valid
196 binding schema. All of the DT binding documents can be validated using the
201 In order to perform validation of DT source files, use the ``dtbs_check`` target::
205 Note that ``dtbs_check`` will skip any binding schema files with errors. It is
207 binding schema files.
213 It is also possible to run checks with a subset of matching schema files by
214 setting the ``DT_SCHEMA_FILES`` variable to 1 or more specific schema files or
220 make dt_binding_check DT_SCHEMA_FILES=trivial-devices.yaml
221 make dt_binding_check DT_SCHEMA_FILES=trivial-devices.yaml:rtc.yaml
223 make dtbs_check DT_SCHEMA_FILES=trivial-devices.yaml
226 json-schema Resources
227 ---------------------
230 `JSON-Schema Specifications <http://json-schema.org/>`_
232 `Using JSON Schema Book <http://usingjsonschema.com/>`_
234 .. _example-schema:
236 Annotated Example Schema
237 ------------------------
239 Also available as a separate file: :download:`example-schema.yaml`
241 .. literalinclude:: example-schema.yaml