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 85 clock-names: 86 items: 87 - const: bus 88 89 interrupts: 90 # Either 1 or 2 interrupts can be present 91 minItems: 1 92 maxItems: 2 93 items: 94 - description: tx or combined interrupt 95 - description: rx interrupt 96 description: 97 A variable number of interrupts warrants a description of what conditions 98 affect the number of interrupts. Otherwise, descriptions on standard 99 properties are not necessary. 100 101 interrupt-names: 102 # minItems must be specified here because the default would be 2 103 minItems: 1 104 maxItems: 2 105 items: 106 - const: tx irq 107 - const: rx irq 108 109 # Property names starting with '#' must be quoted 110 '#interrupt-cells': 111 # A simple case where the value must always be '2'. 112 # The core schema handles that this must be a single integer. 113 const: 2 114 115 interrupt-controller: true 116 # The core checks this is a boolean, so just have to list it here to be 117 # valid for this binding. 118 119 clock-frequency: 120 # The type is set in the core schema. Per device schema only need to set 121 # constraints on the possible values. 122 minimum: 100 123 maximum: 400000 124 # The value that should be used if the property is not present 125 default: 200 126 127 foo-gpios: 128 maxItems: 1 129 description: A connection of the 'foo' gpio line. 130 131 # *-supply is always a single phandle, so nothing more to define. 132 foo-supply: true 133 134 # Vendor specific properties 135 # 136 # Vendor specific properties have slightly different schema requirements than 137 # common properties. They must have at least a type definition and 138 # 'description'. 139 vendor,int-property: 140 description: Vendor specific properties must have a description 141 $ref: /schemas/types.yaml#/definitions/uint32 142 enum: [2, 4, 6, 8, 10] 143 144 vendor,bool-property: 145 description: Vendor specific properties must have a description. Boolean 146 properties are one case where the json-schema 'type' keyword can be used 147 directly. 148 type: boolean 149 150 vendor,string-array-property: 151 description: Vendor specific properties should reference a type in the 152 core schema. 153 $ref: /schemas/types.yaml#/definitions/string-array 154 items: 155 - enum: [foo, bar] 156 - enum: [baz, boo] 157 158 vendor,property-in-standard-units-microvolt: 159 description: Vendor specific properties having a standard unit suffix 160 don't need a type. 161 enum: [ 100, 200, 300 ] 162 163 child-node: 164 description: Child nodes are just another property from a json-schema 165 perspective. 166 type: object # DT nodes are json objects 167 properties: 168 vendor,a-child-node-property: 169 description: Child node properties have all the same schema 170 requirements. 171 type: boolean 172 173 required: 174 - vendor,a-child-node-property 175 176# Describe the relationship between different properties 177dependencies: 178 # 'vendor,bool-property' is only allowed when 'vendor,string-array-property' 179 # is present 180 vendor,bool-property: [ 'vendor,string-array-property' ] 181 # Expressing 2 properties in both orders means all of the set of properties 182 # must be present or none of them. 183 vendor,string-array-property: [ 'vendor,bool-property' ] 184 185required: 186 - compatible 187 - reg 188 - interrupts 189 - interrupt-controller 190 191# if/then schema can be used to handle conditions on a property affecting 192# another property. A typical case is a specific 'compatible' value changes the 193# constraints on other properties. 194# 195# For multiple 'if' schema, group them under an 'allOf'. 196# 197# If the conditionals become too unweldy, then it may be better to just split 198# the binding into separate schema documents. 199if: 200 properties: 201 compatible: 202 contains: 203 const: vendor,soc2-ip 204then: 205 required: 206 - foo-supply 207 208# Ideally, the schema should have this line otherwise any other properties 209# present are allowed. There's a few common properties such as 'status' and 210# 'pinctrl-*' which are added automatically by the tooling. 211# 212# This can't be used in cases where another schema is referenced 213# (i.e. allOf: [{$ref: ...}]). 214additionalProperties: false 215 216examples: 217 # Examples are now compiled with dtc and validated against the schemas 218 # 219 # Examples have a default #address-cells and #size-cells value of 1. This can 220 # be overridden or an appropriate parent bus node should be shown (such as on 221 # i2c buses). 222 # 223 # Any includes used have to be explicitly included. 224 - | 225 node@1000 { 226 compatible = "vendor,soc4-ip", "vendor,soc1-ip"; 227 reg = <0x1000 0x80>, 228 <0x3000 0x80>; 229 reg-names = "core", "aux"; 230 interrupts = <10>; 231 interrupt-controller; 232 }; 233