dtoolkit 0.1.1

A library for parsing and manipulating Flattened Device Tree (FDT) blobs.
Documentation 
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// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use core::fmt::{self, Display, Formatter};
use core::ops::Deref;

use crate::error::{PropertyError, StandardError};
use crate::fdt::{Fdt, FdtNode};
use crate::{Cells, Node, Property};

impl<'a> Fdt<'a> {
    /// Returns the `/cpus` node.
    ///
    /// This should always be included in a valid device tree.
    ///
    /// # Errors
    ///
    /// Returns a parse error if there was a problem reading the FDT structure
    /// to find the node, or [`StandardError::CpusMissing`] if the CPUs node is
    /// missing.
    pub fn cpus(self) -> Result<Cpus<FdtNode<'a>>, StandardError> {
        let node = self.find_node("/cpus").ok_or(StandardError::CpusMissing)?;
        Ok(Cpus { node })
    }
}

/// Typed wrapper for a `/cpus` node.
#[derive(Clone, Copy, Debug)]
pub struct Cpus<N> {
    node: N,
}

impl<N> Deref for Cpus<N> {
    type Target = N;

    fn deref(&self) -> &Self::Target {
        &self.node
    }
}

impl<N: Display> Display for Cpus<N> {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        self.node.fmt(f)
    }
}

impl<'a, N: Node<'a>> Cpus<N> {
    /// Returns an iterator over the `/cpus/cpu@*` nodes.
    pub fn cpus(&self) -> impl Iterator<Item = Cpu<N>> + use<'a, N> {
        self.node.children().filter_map(|child| {
            if child.name_without_address() == "cpu" {
                Some(Cpu { node: child })
            } else {
                None
            }
        })
    }
}

/// Typed wrapper for a `/cpus/cpu` node.
#[derive(Clone, Copy, Debug)]
pub struct Cpu<N> {
    node: N,
}

impl<N> Deref for Cpu<N> {
    type Target = N;

    fn deref(&self) -> &Self::Target {
        &self.node
    }
}

impl<N: Display> Display for Cpu<N> {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        self.node.fmt(f)
    }
}

impl<'a, N: Node<'a>> Cpu<N> {
    /// Returns the value of the standard `enable-method` property if it is
    /// present.
    pub fn enable_method(&self) -> Option<impl Iterator<Item = &'a str>> {
        Some(self.node.property("enable-method")?.as_str_list())
    }

    /// Returns the value of the standard `cpu-release-addr` property if it is
    /// present.
    ///
    /// # Errors
    ///
    /// Returns an error if the value of the property isn't 8 bytes long.
    pub fn cpu_release_addr(&self) -> Result<Option<u64>, PropertyError> {
        self.node
            .property("cpu-release-addr")
            .map(|value| value.as_u64())
            .transpose()
    }
}

impl<'a> Cpu<FdtNode<'a>> {
    /// Returns an iterator over the IDs of the CPU, from the standard `reg`
    /// property.
    ///
    /// # Errors
    ///
    /// Returns an error if a property's name or value cannot be read, or the
    /// `reg` property is missing, or the size of the value isn't a multiple of
    /// the expected number of address and size cells.
    pub fn ids(&self) -> Result<impl Iterator<Item = Cells<'a>> + use<'a>, StandardError> {
        Ok(self
            .node
            .reg()?
            .ok_or(StandardError::CpuMissingReg)?
            .map(|reg| reg.address))
    }
}