fdt-rs

A Flattened Device Tree parser for embedded no-std environments

Usage

Add this to your Cargo.toml:

[dependencies.fdt-rs]
version = "0.2"

and this to your crate root:

extern crate fdt_rs;

Features

This crate can be used without the standard library (#![no_std]) by disabling the default std feature. Use this in Cargo.toml:

[dependencies.fdt-rs]
version = "0.2"
default-features = false
# features = ["ascii"]    # <--- Uncomment if you wish to use the ascii crate for str's

The "ascii" feature will configure the Str type returned by string accessor methods to be of type AsciiStr provided by the ascii crate. Without this feature enabled, str references will be returned.

Example

The following example stashes a flattened device tree in memory, parses that device tree into a fdt_rs::DevTree object, searches the device tree for the first "ns16550a" compatible node, and if found prints that node's name.

extern crate fdt_rs;
use fdt_rs::*;

// Place a device tree image into the rust binary and
// align it to a 32-byte boundary by using a wrapper struct.
#[repr(align(4))] struct _Wrapper<T>(T);
pub const FDT: &[u8] = &_Wrapper(*include_bytes!("../tests/riscv64-virt.dtb")).0;

fn main() {
    // Initialize the devtree using an &[u8] array.
    let devtree = unsafe {

        // Get the actual size of the device tree after reading its header.
        let size = DevTree::read_totalsize(FDT).unwrap();
        let buf = &FDT[..size];

        // Create the device tree handle
        DevTree::new(buf).unwrap()
    };

    // Find the first "ns16550a" compatible node within the device tree.
    // If found, print the name of that node (including unit address).
    if let Some(node) = devtree.find_first_compatible_node("ns16550a") {
        println!("{}", node.name().unwrap());
    }


    // Use our own custom search method to find bootargs
    //
    // Find a node with a custom zero-length property "company,secret"
    if let Some((compatible_prop, _)) = devtree.find_prop(
            |prop|
                Ok((prop.name()? == "bootargs"))) {
        unsafe {
            println!("{}", compatible_prop.get_str().unwrap());
        }
    }
}