Platform Driver and Device Tree Binding¶

A platform driver is commonly used for devices that are not discoverable by a hardware enumeration bus. On embedded Linux systems, the Device Tree describes the hardware, and the kernel matches Device Tree nodes to platform drivers through the compatible property.

Binding Flow¶

Device Tree node
    compatible = "myvendor,mygpio-led"
        ↓
of_device_id table
        ↓
platform_driver
        ↓
probe()

Key Names¶

Name	Role
Device Tree node name	Human-readable hardware node name
Device Tree label	Internal DTS reference label
`compatible`	Driver matching key
Driver name	Kernel-side driver identity
`/dev/<name>`	User-space device node created by the driver

GPIO Resource Mapping¶

Modern GPIO drivers should request GPIOs by function name, not by global GPIO number.

devm_gpiod_get(dev, "led", GPIOD_OUT_LOW);

This maps to the Device Tree property:

led-gpios = <&gpio 17 GPIO_ACTIVE_HIGH>;

Common Pitfalls¶

Warning

The Device Tree node name does not decide which driver is used. The compatible string does.

Warning

The name passed to devm_gpiod_get(dev, "xxx", ...) maps to the Device Tree property xxx-gpios.