DeviceTree on Rishav's Digital Garden

Device Tree (DT) in Linux Kernel

Mon, 27 Jan 2025 17:41:00 +0000

Overview

The Device Tree (DT) is a data structure used to describe the hardware components of a system in a way that is independent of the operating system and software. It is particularly relevant for systems based on the ARM architecture, where the hardware varies significantly across devices.

Instead of hardcoding hardware details in the kernel, the device tree provides a flexible way to inform the kernel about the system’s hardware layout. This simplifies kernel code and enables easier reuse across multiple hardware platforms.

Example Image Tree Source File (.its)

Fri, 08 Nov 2024 11:31:00 +0000

Example Image Tree Source (`.its`) file

/dts-v1/;
/ {
description = "U-Boot FIT source file for arm";
images {
uboot {
data = /incbin/("uboot.img.enc");
type = "standalone";
arch = "arm64";
compression = "none";
load = <0xffffff00>;
hash {
algo = "sha256";
};
};
};
configurations {
default = "conf";
conf {
rollback-index = <0x00>;
uboot = "uboot";
board-type = "MU_BOARD";
signature {
algo = "sha256,rsa2048";
padding = "pss";
key-name-hint = "dev";
sign-images = "uboot";
};
};
};
};

References

https://devicetree-specification.readthedocs.io/en/stable/index.html

Flattened Devicetree (DTB) Format

Fri, 08 Nov 2024 11:31:00 +0000

Device Tree

Standard Properties

compatible

The compatible property value consists of one or more strings that define the specific programming model for the device. This list of strings should be used by a client program for device driver selection. The property value consists of a concatenated list of null terminated strings, from most specific to most general. They allow a device to express its compatibility with a family of similar devices, potentially allowing a single device driver to match against several devices.