1# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) 2# Copyright 2018 Linaro Ltd. 3%YAML 1.2 4--- 5# All the top-level keys are standard json-schema keywords except for 6# 'maintainers' and 'select' 7 8# $id is a unique identifier based on the filename. There may or may not be a 9# file present at the URL. 10$id: http://devicetree.org/schemas/example-schema.yaml# 11# $schema is the meta-schema this schema should be validated with. 12$schema: http://devicetree.org/meta-schemas/core.yaml# 13 14title: An example schema annotated with jsonschema details 15 16maintainers: 17 - Rob Herring <robh@kernel.org> 18 19description: | 20 A more detailed multi-line description of the binding. 21 22 Details about the hardware device and any links to datasheets can go here. 23 24 Literal blocks are marked with the '|' at the beginning. The end is marked by 25 indentation less than the first line of the literal block. Lines also cannot 26 begin with a tab character. 27 28select: false 29 # 'select' is a schema applied to a DT node to determine if this binding 30 # schema should be applied to the node. It is optional and by default the 31 # possible compatible strings are extracted and used to match. 32 33 # In this case, a 'false' schema will never match. 34 35properties: 36 # A dictionary of DT properties for this binding schema 37 compatible: 38 # More complicated schema can use oneOf (XOR), anyOf (OR), or allOf (AND) 39 # to handle different conditions. 40 # In this case, it's needed to handle a variable number of values as there 41 # isn't another way to express a constraint of the last string value. 42 # The boolean schema must be a list of schemas. 43 oneOf: 44 - items: 45 # items is a list of possible values for the property. The number of 46 # values is determined by the number of elements in the list. 47 # Order in lists is significant, order in dicts is not 48 # Must be one of the 1st enums followed by the 2nd enum 49 # 50 # Each element in items should be 'enum' or 'const' 51 - enum: 52 - vendor,soc4-ip 53 - vendor,soc3-ip 54 - vendor,soc2-ip 55 - enum: 56 - vendor,soc1-ip 57 # additionalItems being false is implied 58 # minItems/maxItems equal to 2 is implied 59 - items: 60 # 'const' is just a special case of an enum with a single possible value 61 - const: vendor,soc1-ip 62 63 reg: 64 # The core schema already checks that reg values are numbers, so device 65 # specific schema don't need to do those checks. 66 # The description of each element defines the order and implicitly defines 67 # the number of reg entries. 68 items: 69 - description: core registers 70 - description: aux registers 71 # minItems/maxItems equal to 2 is implied 72 73 reg-names: 74 # The core schema enforces this (*-names) is a string array 75 items: 76 - const: core 77 - const: aux 78 79 clocks: 80 # Cases that have only a single entry just need to express that with maxItems 81 maxItems: 1 82 description: bus clock. A description is only needed for a single item if 83 there's something unique to add. 84 The items should have a fixed order, so pattern matching names are 85 discouraged. 86 87 clock-names: 88 items: 89 - const: bus 90 91 interrupts: 92 # Either 1 or 2 interrupts can be present 93 minItems: 1 94 items: 95 - description: tx or combined interrupt 96 - description: rx interrupt 97 description: 98 A variable number of interrupts warrants a description of what conditions 99 affect the number of interrupts. Otherwise, descriptions on standard 100 properties are not necessary. 101 The items should have a fixed order, so pattern matching names are 102 discouraged. 103 104 interrupt-names: 105 # minItems must be specified here because the default would be 2 106 minItems: 1 107 items: 108 - const: tx irq 109 - const: rx irq 110 111 # Property names starting with '#' must be quoted 112 '#interrupt-cells': 113 # A simple case where the value must always be '2'. 114 # The core schema handles that this must be a single integer. 115 const: 2 116 117 interrupt-controller: true 118 # The core checks this is a boolean, so just have to list it here to be 119 # valid for this binding. 120 121 clock-frequency: 122 # The type is set in the core schema. Per-device schema only need to set 123 # constraints on the possible values. 124 minimum: 100 125 maximum: 400000 126 # The value that should be used if the property is not present 127 default: 200 128 129 foo-gpios: 130 maxItems: 1 131 description: A connection of the 'foo' gpio line. 132 133 # *-supply is always a single phandle, so nothing more to define. 134 foo-supply: true 135 136 # Vendor-specific properties 137 # 138 # Vendor-specific properties have slightly different schema requirements than 139 # common properties. They must have at least a type definition and 140 # 'description'. 141 vendor,int-property: 142 description: Vendor-specific properties must have a description 143 $ref: /schemas/types.yaml#/definitions/uint32 144 enum: [2, 4, 6, 8, 10] 145 146 vendor,bool-property: 147 description: Vendor-specific properties must have a description. Boolean 148 properties are one case where the json-schema 'type' keyword can be used 149 directly. 150 type: boolean 151 152 vendor,string-array-property: 153 description: Vendor-specific properties should reference a type in the 154 core schema. 155 $ref: /schemas/types.yaml#/definitions/string-array 156 items: 157 - enum: [foo, bar] 158 - enum: [baz, boo] 159 160 vendor,property-in-standard-units-microvolt: 161 description: Vendor-specific properties having a standard unit suffix 162 don't need a type. 163 enum: [ 100, 200, 300 ] 164 165 vendor,int-array-variable-length-and-constrained-values: 166 description: Array might define what type of elements might be used (e.g. 167 their range). 168 $ref: /schemas/types.yaml#/definitions/uint32-array 169 minItems: 2 170 maxItems: 3 171 items: 172 minimum: 0 173 maximum: 8 174 175 child-node: 176 description: Child nodes are just another property from a json-schema 177 perspective. 178 type: object # DT nodes are json objects 179 properties: 180 vendor,a-child-node-property: 181 description: Child node properties have all the same schema 182 requirements. 183 type: boolean 184 185 required: 186 - vendor,a-child-node-property 187 188# Describe the relationship between different properties 189dependencies: 190 # 'vendor,bool-property' is only allowed when 'vendor,string-array-property' 191 # is present 192 vendor,bool-property: [ 'vendor,string-array-property' ] 193 # Expressing 2 properties in both orders means all of the set of properties 194 # must be present or none of them. 195 vendor,string-array-property: [ 'vendor,bool-property' ] 196 197required: 198 - compatible 199 - reg 200 - interrupts 201 - interrupt-controller 202 203# if/then schema can be used to handle conditions on a property affecting 204# another property. A typical case is a specific 'compatible' value changes the 205# constraints on other properties. 206# 207# For multiple 'if' schema, group them under an 'allOf'. 208# 209# If the conditionals become too unweldy, then it may be better to just split 210# the binding into separate schema documents. 211allOf: 212 - if: 213 properties: 214 compatible: 215 contains: 216 const: vendor,soc2-ip 217 then: 218 required: 219 - foo-supply 220 else: 221 # If otherwise the property is not allowed: 222 properties: 223 foo-supply: false 224 # Altering schema depending on presence of properties is usually done by 225 # dependencies (see above), however some adjustments might require if: 226 - if: 227 required: 228 - vendor,bool-property 229 then: 230 properties: 231 vendor,int-property: 232 enum: [2, 4, 6] 233 234# Ideally, the schema should have this line otherwise any other properties 235# present are allowed. There's a few common properties such as 'status' and 236# 'pinctrl-*' which are added automatically by the tooling. 237# 238# This can't be used in cases where another schema is referenced 239# (i.e. allOf: [{$ref: ...}]). 240# If and only if another schema is referenced and arbitrary children nodes can 241# appear, "unevaluatedProperties: false" could be used. A typical example is 242# an I2C controller where no name pattern matching for children can be added. 243additionalProperties: false 244 245examples: 246 # Examples are now compiled with dtc and validated against the schemas 247 # 248 # Examples have a default #address-cells and #size-cells value of 1. This can 249 # be overridden or an appropriate parent bus node should be shown (such as on 250 # i2c buses). 251 # 252 # Any includes used have to be explicitly included. Use 4-space indentation. 253 - | 254 node@1000 { 255 compatible = "vendor,soc4-ip", "vendor,soc1-ip"; 256 reg = <0x1000 0x80>, 257 <0x3000 0x80>; 258 reg-names = "core", "aux"; 259 interrupts = <10>; 260 interrupt-controller; 261 }; 262