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Devicetree bindings syntax

This page documents the syntax of Zephyr’s bindings format. Zephyr bindings files are YAML files. A simple example was given in the introduction page.

Top level keys

The top level of a bindings file maps keys to values. The top-level keys look like this:

# A high level description of the device the binding applies to:
description: |
   This is the Vendomatic company's foo-device.

   Descriptions which span multiple lines (like this) are OK,
   and are encouraged for complex bindings.

   See for formatting help.

# You can include definitions from other bindings using this syntax:
include: other.yaml

# Used to match nodes to this binding:
compatible: "manufacturer,foo-device"

  # Requirements for and descriptions of the properties that this
  # binding's nodes need to satisfy go here.

  # You can constrain the children of the nodes matching this binding
  # using this key.

# If the node describes bus hardware, like an SPI bus controller
# on an SoC, use 'bus:' to say which one, like this:
bus: spi

# If the node instead appears as a device on a bus, like an external
# SPI memory chip, use 'on-bus:' to say what type of bus, like this.
# Like 'compatible', this key also influences the way nodes match
# bindings.
on-bus: spi

  # "Specifier" cell names for the 'foo' domain go here; example 'foo'
  # values are 'gpio', 'pwm', and 'dma'. See below for more information.

These keys are explained in the following sections.


A free-form description of node hardware goes here. You can put links to datasheets or example nodes or properties as well.


This key is used to match nodes to this binding as described in Introduction to Devicetree Bindings. It should look like this in a binding file:

# Note the comma-separated vendor prefix and device name
compatible: "manufacturer,device"

This devicetree node would match the above binding:

device {
     compatible = "manufacturer,device";

Assuming no binding has compatible: "manufacturer,device-v2", it would also match this node:

device-2 {
    compatible = "manufacturer,device-v2", "manufacturer,device";

Each node’s compatible property is tried in order. The first matching binding is used. The on-bus: key can be used to refine the search.

If more than one binding for a compatible is found, an error is raised.

The manufacturer prefix identifies the device vendor. See dts/bindings/vendor-prefixes.txt for a list of accepted vendor prefixes. The device part is usually from the datasheet.

Some bindings apply to a generic class of devices which do not have a specific vendor. In these cases, there is no vendor prefix. One example is the gpio-leds compatible which is commonly used to describe board LEDs connected to GPIOs.


The properties: key describes properties that nodes which match the binding contain. For example, a binding for a UART peripheral might look something like this:

compatible: "manufacturer,serial"

    type: array
    description: UART peripheral MMIO register space
    required: true
    type: int
    description: current baud rate
    required: true

In this example, a node with compatible "manufacturer,serial" must contain a node named current-speed. The property’s value must be a single integer. Similarly, the node must contain a reg property.

The build system uses bindings to generate C macros for devicetree properties that appear in DTS files. You can read more about how to get property values in source code from these macros in Devicetree access from C/C++. Generally speaking, the build system only generates macros for properties listed in the properties: key for the matching binding. Properties not mentioned in the binding are generally ignored by the build system.

The one exception is that the build system will always generate macros for standard properties, like reg, whose meaning is defined by the devicetree specification. This happens regardless of whether the node has a matching binding or not.

Property entry syntax

Property entries in properties: are written in this syntax:

<property name>:
  required: <true | false>
  type: <string | int | boolean | array | uint8-array | string-array |
         phandle | phandles | phandle-array | path | compound>
  deprecated: <true | false>
  default: <default>
  description: <description of the property>
    - <item1>
    - <item2>
    - <itemN>
  const: <string | int | array | uint8-array | string-array>
  specifier-space: <space-name>

Example property definitions

Here are some more examples.

    # Describes a property like 'current-speed = <115200>;'. We pretend that
    # it's obligatory for the example node and set 'required: true'.
        type: int
        required: true
        description: Initial baud rate for bar-device

    # Describes an optional property like 'keys = "foo", "bar";'
        type: string-array
        description: Keys for bar-device

    # Describes an optional property like 'maximum-speed = "full-speed";'
    # the enum specifies known values that the string property may take
        type: string
        description: Configures USB controllers to work up to a specific speed.
           - "low-speed"
           - "full-speed"
           - "high-speed"
           - "super-speed"

    # Describes an optional property like 'resolution = <16>;'
    # the enum specifies known values that the int property may take
      type: int
       - 8
       - 16
       - 24
       - 32

    # Describes a required property '#address-cells = <1>';  the const
    # specifies that the value for the property is expected to be the value 1
        type: int
        required: true
        const: 1

        type: int
        default: 123
        description: Value for int register, default is power-up configuration.

        type: array
        default: [1, 2, 3] # Same as 'array-with-default = <1 2 3>'

        type: string
        default: "foo"

        type: string-array
        default: ["foo", "bar"] # Same as 'string-array-with-default = "foo", "bar"'

        type: uint8-array
        default: [0x12, 0x34] # Same as 'uint8-array-with-default = [12 34]'


Adding required: true to a property definition will fail the build if a node matches the binding, but does not contain the property.

The default setting is required: false; that is, properties are optional by default. Using required: false is therefore redundant and strongly discouraged.


The type of a property constrains its values. The following types are available. See Writing property values for more details about writing values of each type in a DTS file. See Phandles for more information about the phandle* type properties.



Example in DTS


exactly one string

status = "disabled";


exactly one 32-bit value (cell)

current-speed = <115200>;


flags that don’t take a value when true, and are absent if false



zero or more 32-bit values (cells)

offsets = <0x100 0x200 0x300>;


zero or more bytes, in hex (‘bytestring’ in the Devicetree specification)

local-mac-address = [de ad be ef 12 34];


zero or more strings

dma-names = "tx", "rx";


exactly one phandle

interrupt-parent = <&gic>;


zero or more phandles

pinctrl-0 = <&usart2_tx_pd5 &usart2_rx_pd6>;


a list of phandles and 32-bit cells (usually specifiers)

dmas = <&dma0 2>, <&dma0 3>;


a path to a node as a phandle path reference or path string

zephyr,bt-c2h-uart = &uart0; or foo = "/path/to/some/node";


a catch-all for more complex types (no macros will be generated)

foo = <&label>, [01 02];


A property with deprecated: true indicates to both the user and the tooling that the property is meant to be phased out.

The tooling will report a warning if the devicetree includes the property that is flagged as deprecated. (This warning is upgraded to an error in the Test Runner (Twister) for upstream pull requests.)

The default setting is deprecated: false. Using deprecated: false is therefore redundant and strongly discouraged.


The optional default: setting gives a value that will be used if the property is missing from the devicetree node.

For example, with this binding fragment:

    type: int
    default: 3

If property foo is missing in a matching node, then the output will be as if foo = <3>; had appeared in the DTS (except YAML data types are used for the default value).

Note that combining default: with required: true will raise an error.

For rules related to default in upstream Zephyr bindings, see Rules for default values.

See Example property definitions for examples. Putting default: on any property type besides those used in Example property definitions will raise an error.


The enum: line is followed by a list of values the property may contain. If a property value in DTS is not in the enum: list in the binding, an error is raised. See Example property definitions for examples.


This specifies a constant value the property must take. It is mainly useful for constraining the values of common properties for a particular piece of hardware.



It is an abuse of this feature to use it to name properties in unconventional ways.

For example, this feature is not meant for cases like naming a property my-pin, then assigning it to the “gpio” specifier space using this feature. Properties which refer to GPIOs should use conventional names, i.e. end in -gpios or -gpio.

This property, if present, manually sets the specifier space associated with a property with type phandle-array.

Normally, the specifier space is encoded implicitly in the property name. A property named foos with type phandle-array implicitly has specifier space foo. As a special case, *-gpios properties have specifier space “gpio”, so that foo-gpios will have specifier space “gpio” rather than “foo-gpio”.

You can use specifier-space to manually provide a space if using this convention would result in an awkward or unconventional name.

For example:

compatible: ...
    type: phandle-array
    specifier-space: my-custom-space

Above, the bar property’s specifier space is set to “my-custom-space”.

You could then use the property in a devicetree like this:

controller1: custom-controller@1000 {
        #my-custom-space-cells = <2>;

controller2: custom-controller@2000 {
        #my-custom-space-cells = <1>;

my-node {
        bar = <&controller1 10 20>, <&controller2 30>;

Generally speaking, you should reserve this feature for cases where the implicit specifier space naming convention doesn’t work. One appropriate example is an mboxes property with specifier space “mbox”, not “mboxe”. You can write this property as follows:

    type: phandle-array
    specifier-space: mbox


child-binding can be used when a node has children that all share the same properties. Each child gets the contents of child-binding as its binding, though an explicit compatible = ... on the child node takes precedence, if a binding is found for it.

Consider a binding for a PWM LED node like this one, where the child nodes are required to have a pwms property:

pwmleds {
        compatible = "pwm-leds";

        red_pwm_led {
                pwms = <&pwm3 4 15625000>;
        green_pwm_led {
                pwms = <&pwm3 0 15625000>;
        /* ... */

The binding would look like this:

compatible: "pwm-leds"

  description: LED that uses PWM

      type: phandle-array
      required: true

child-binding also works recursively. For example, this binding:

compatible: foo

        type: int
        required: true

will apply to the grandchild node in this DTS:

parent {
        compatible = "foo";
        child {
                grandchild {
                        my-property = <123>;


If the node is a bus controller, use bus: in the binding to say what type of bus. For example, a binding for a SPI peripheral on an SoC would look like this:

compatible: "manufacturer,spi-peripheral"
bus: spi
# ...

The presence of this key in the binding informs the build system that the children of any node matching this binding appear on this type of bus.

This in turn influences the way on-bus: is used to match bindings for the child nodes.

For a single bus supporting multiple protocols, e.g. I3C and I2C, the bus: in the binding can have a list as value:

compatible: "manufacturer,i3c-controller"
bus: [i3c, i2c]
# ...


If the node appears as a device on a bus, use on-bus: in the binding to say what type of bus.

For example, a binding for an external SPI memory chip should include this line:

on-bus: spi

And a binding for an I2C based temperature sensor should include this line:

on-bus: i2c

When looking for a binding for a node, the build system checks if the binding for the parent node contains bus: <bus type>. If it does, then only bindings with a matching on-bus: <bus type> and bindings without an explicit on-bus are considered. Bindings with an explicit on-bus: <bus type> are searched for first, before bindings without an explicit on-bus. The search repeats for each item in the node’s compatible property, in order.

This feature allows the same device to have different bindings depending on what bus it appears on. For example, consider a sensor device with compatible manufacturer,sensor which can be used via either I2C or SPI.

The sensor node may therefore appear in the devicetree as a child node of either an SPI or an I2C controller, like this:

spi-bus@0 {
   /* ... some compatible with 'bus: spi', etc. ... */

   sensor@0 {
       compatible = "manufacturer,sensor";
       reg = <0>;
       /* ... */

i2c-bus@0 {
   /* ... some compatible with 'bus: i2c', etc. ... */

   sensor@79 {
       compatible = "manufacturer,sensor";
       reg = <79>;
       /* ... */

You can write two separate binding files which match these individual sensor nodes, even though they have the same compatible:

# manufacturer,sensor-spi.yaml, which matches sensor@0 on the SPI bus:
compatible: "manufacturer,sensor"
on-bus: spi

# manufacturer,sensor-i2c.yaml, which matches sensor@79 on the I2C bus:
compatible: "manufacturer,sensor"
    type: boolean
on-bus: i2c

Only sensor@79 can have a use-clock-stretching property. The bus-sensitive logic ignores manufacturer,sensor-i2c.yaml when searching for a binding for sensor@0.

Specifier cell names (*-cells)

This section documents how to name the cells in a specifier within a binding. These concepts are discussed in detail later in this guide in phandle-array properties.

Consider a binding for a node whose phandle may appear in a phandle-array property, like the PWM controllers pwm1 and pwm2 in this example:

pwm1: pwm@deadbeef {
    compatible = "foo,pwm";
    #pwm-cells = <2>;

pwm2: pwm@deadbeef {
    compatible = "bar,pwm";
    #pwm-cells = <1>;

my-node {
    pwms = <&pwm1 1 2000>, <&pwm2 3000>;

The bindings for compatible "foo,pwm" and "bar,pwm" must give a name to the cells that appear in a PWM specifier using pwm-cells:, like this:

# foo,pwm.yaml
compatible: "foo,pwm"
  - channel
  - period

# bar,pwm.yaml
compatible: "bar,pwm"
  - period

A *-names (e.g. pwm-names) property can appear on the node as well, giving a name to each entry.

This allows the cells in the specifiers to be accessed by name, e.g. using APIs like DT_PWMS_CHANNEL_BY_NAME.

If the specifier is empty (e.g. #clock-cells = <0>), then *-cells can either be omitted (recommended) or set to an empty array. Note that an empty array is specified as e.g. clock-cells: [] in YAML.


Bindings can include other files, which can be used to share common property definitions between bindings. Use the include: key for this. Its value is either a string or a list.

In the simplest case, you can include another file by giving its name as a string, like this:

include: foo.yaml

If any file named foo.yaml is found (see Where bindings are located for the search process), it will be included into this binding.

Included files are merged into bindings with a simple recursive dictionary merge. The build system will check that the resulting merged binding is well-formed. It is allowed to include at any level, including child-binding, like this:

# foo.yaml will be merged with content at this level
include: foo.yaml

  # bar.yaml will be merged with content at this level
  include: bar.yaml

It is an error if a key appears with a different value in a binding and in a file it includes, with one exception: a binding can have required: true for a property definition for which the included file has required: false. The required: true takes precedence, allowing bindings to strengthen requirements from included files.

Note that weakening requirements by having required: false where the included file has required: true is an error. This is meant to keep the organization clean.

The file base.yaml contains definitions for many common properties. When writing a new binding, it is a good idea to check if base.yaml already defines some of the needed properties, and include it if it does.

Note that you can make a property defined in base.yaml obligatory like this, taking reg as an example:

  required: true

This relies on the dictionary merge to fill in the other keys for reg, like type.

To include multiple files, you can use a list of strings:

  - foo.yaml
  - bar.yaml

This includes the files foo.yaml and bar.yaml. (You can write this list in a single line of YAML as include: [foo.yaml, bar.yaml].)

When including multiple files, any overlapping required keys on properties in the included files are ORed together. This makes sure that a required: true is always respected.

In some cases, you may want to include some property definitions from a file, but not all of them. In this case, include: should be a list, and you can filter out just the definitions you want by putting a mapping in the list, like this:

  - name: foo.yaml
      - i-want-this-one
      - and-this-one
  - name: bar.yaml
      - do-not-include-this-one
      - or-this-one

Each map element must have a name key which is the filename to include, and may have property-allowlist and property-blocklist keys that filter which properties are included.

You cannot have a single map element with both property-allowlist and property-blocklist keys. A map element with neither property-allowlist nor property-blocklist is valid; no additional filtering is done.

You can freely intermix strings and mappings in a single include: list:

  - foo.yaml
  - name: bar.yaml
      - do-not-include-this-one
      - or-this-one

Finally, you can filter from a child binding like this:

  - name: bar.yaml
        - child-prop-to-allow

Nexus nodes and maps

All phandle-array type properties support mapping through *-map properties, e.g. gpio-map, as defined by the Devicetree specification.

This is used, for example, to define connector nodes for common breakout headers, such as the arduino_header nodes that are conventionally defined in the devicetrees for boards with Arduino compatible expansion headers.