feat: add more types and methods for standard nodes (#25)

* Add methods to get standard /reserved-memory subnodes and properties.

* Add methods to get standard /chosen node and properties.

* Add more methods for standard properties on CPU nodes.

Author: qwandor

src/lib.rs

@@ -258,6 +258,19 @@ pub trait Property<'a>: Sized {
             .map_err(|_| PropertyError::InvalidLength)
     }
 
+    /// Returns the value of this property as a slide of 32-bit cells.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the value of the property isn't a multiple of 4
+    /// bytes long.
+    fn as_cells(&self) -> Result<Cells<'a>, PropertyError> {
+        Ok(Cells(
+            <[big_endian::U32]>::ref_from_bytes(self.value())
+                .map_err(|_| PropertyError::InvalidLength)?,
+        ))
+    }
+
     /// Returns the value of this property as a string.
     ///
     /// # Errors

src/standard.rs

@@ -8,14 +8,16 @@
 
 //! Standard nodes and properties.
 
+mod chosen;
 mod cpus;
 mod memory;
 mod ranges;
 mod reg;
 mod status;
 
+pub use self::chosen::Chosen;
 pub use self::cpus::{Cpu, Cpus};
-pub use self::memory::{InitialMappedArea, Memory};
+pub use self::memory::{InitialMappedArea, Memory, ReservedMemory};
 pub use self::ranges::Range;
 pub use self::reg::Reg;
 pub use self::status::Status;

src/standard/chosen.rs

@@ -0,0 +1,84 @@
+// Copyright 2026 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;
+use crate::fdt::{Fdt, FdtNode};
+use crate::{Node, Property};
+
+impl<'a> Fdt<'a> {
+    /// Returns the `/chosen` node, if it exists.
+    #[must_use]
+    pub fn chosen(self) -> Option<Chosen<FdtNode<'a>>> {
+        let node = self.find_node("/chosen")?;
+        Some(Chosen { node })
+    }
+}
+
+/// Typed wrapper for a `/chosen` node.
+#[derive(Clone, Copy, Debug)]
+pub struct Chosen<N> {
+    node: N,
+}
+
+impl<N> Deref for Chosen<N> {
+    type Target = N;
+
+    fn deref(&self) -> &Self::Target {
+        &self.node
+    }
+}
+
+impl<N: Display> Display for Chosen<N> {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        self.node.fmt(f)
+    }
+}
+
+impl<'a, N: Node<'a>> Chosen<N> {
+    /// Returns the value of the standard `bootargs` property.
+    ///
+    /// # Errors
+    ///
+    /// Returns an [`PropertyError::InvalidString`] if the property's value is
+    /// not a null-terminated string or contains invalid UTF-8.
+    pub fn bootargs(&self) -> Result<Option<&'a str>, PropertyError> {
+        self.node
+            .property("bootargs")
+            .map(|value| value.as_str())
+            .transpose()
+    }
+
+    /// Returns the value of the standard `stdout-path` property.
+    ///
+    /// # Errors
+    ///
+    /// Returns an [`PropertyError::InvalidString`] if the property's value is
+    /// not a null-terminated string or contains invalid UTF-8.
+    pub fn stdout_path(&self) -> Result<Option<&'a str>, PropertyError> {
+        self.node
+            .property("stdout-path")
+            .map(|value| value.as_str())
+            .transpose()
+    }
+
+    /// Returns the value of the standard `stdin-path` property.
+    ///
+    /// # Errors
+    ///
+    /// Returns an [`PropertyError::InvalidString`] if the property's value is
+    /// not a null-terminated string or contains invalid UTF-8.
+    pub fn stdin_path(&self) -> Result<Option<&'a str>, PropertyError> {
+        self.node
+            .property("stdin-path")
+            .map(|value| value.as_str())
+            .transpose()
+    }
+}

src/standard/cpus.rs

@@ -9,9 +9,9 @@
 use core::fmt::{self, Display, Formatter};
 use core::ops::Deref;
 
-use crate::error::StandardError;
+use crate::error::{PropertyError, StandardError};
 use crate::fdt::{Fdt, FdtNode};
-use crate::{Cells, Node};
+use crate::{Cells, Node, Property};
 
 impl<'a> Fdt<'a> {
     /// Returns the `/cpus` node.
@@ -82,6 +82,27 @@ impl<N: Display> Display for Cpu<N> {
     }
 }
 
+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.

src/standard/memory.rs

@@ -11,6 +11,7 @@ use core::ops::Deref;
 
 use crate::error::{PropertyError, StandardError};
 use crate::fdt::{Fdt, FdtNode};
+use crate::standard::Reg;
 use crate::{Cells, Node, Property};
 
 impl<'a> Fdt<'a> {
@@ -27,6 +28,16 @@ impl<'a> Fdt<'a> {
             .ok_or(StandardError::MemoryMissing)?;
         Ok(Memory { node })
     }
+
+    /// Returns the `/reserved-memory/*` nodes, if any.
+    #[must_use]
+    pub fn reserved_memory(self) -> Option<impl Iterator<Item = ReservedMemory<FdtNode<'a>>>> {
+        Some(
+            self.find_node("/reserved-memory")?
+                .children()
+                .map(|node| ReservedMemory { node }),
+        )
+    }
 }
 
 /// Typed wrapper for a `/memory` node.
@@ -107,3 +118,92 @@ impl InitialMappedArea {
         }
     }
 }
+
+/// Typed wrapper for a `/reserved-memory/*` node.
+#[derive(Clone, Copy, Debug)]
+pub struct ReservedMemory<N> {
+    node: N,
+}
+
+impl<N> Deref for ReservedMemory<N> {
+    type Target = N;
+
+    fn deref(&self) -> &Self::Target {
+        &self.node
+    }
+}
+
+impl<N: Display> Display for ReservedMemory<N> {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        self.node.fmt(f)
+    }
+}
+
+impl<'a, N: Node<'a>> ReservedMemory<N> {
+    /// Returns the value of the standard `size` property of the reserved memory
+    /// node, if it is present.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the value of the property isn't a multiple of 4
+    /// bytes long.
+    pub fn size(&self) -> Result<Option<Cells<'a>>, PropertyError> {
+        self.node
+            .property("size")
+            .map(|value| value.as_cells())
+            .transpose()
+    }
+
+    /// Returns the value of the standard `alignment` property of the reserved
+    /// memory node, if it is present.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the value of the property isn't a multiple of 4
+    /// bytes long.
+    pub fn alignment(&self) -> Result<Option<Cells<'a>>, PropertyError> {
+        self.node
+            .property("alignment")
+            .map(|value| value.as_cells())
+            .transpose()
+    }
+
+    /// Returns whether the standard `no-map` property is present.
+    pub fn no_map(&self) -> bool {
+        self.node.property("no-map").is_some()
+    }
+
+    /// Returns whether the standard `no-map-fixup` property is present.
+    pub fn no_map_fixup(&self) -> bool {
+        self.node.property("no-map-fixup").is_some()
+    }
+
+    /// Returns whether the standard `reusable` property is present.
+    pub fn reusable(&self) -> bool {
+        self.node.property("reusable").is_some()
+    }
+}
+
+impl<'a> ReservedMemory<FdtNode<'a>> {
+    /// Returns the value of the standard `alloc-ranges` property.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the size of the value isn't a multiple of the
+    /// expected number of address and size cells.
+    pub fn alloc_ranges(
+        &self,
+    ) -> Result<Option<impl Iterator<Item = Reg<'a>> + use<'a>>, StandardError> {
+        let address_cells = self.node.parent_address_space.address_cells as usize;
+        let size_cells = self.node.parent_address_space.size_cells as usize;
+        if let Some(property) = self.property("alloc_ranges") {
+            Ok(Some(
+                property
+                    .as_prop_encoded_array([address_cells, size_cells])?
+                    .map(Reg::from_cells),
+            ))
+        } else {
+            Ok(None)
+        }
+    }
+}

tests/dtb/test_pretty_print.dtb

@@ -26,4 +26,20 @@
         initial-mapped-area = <0x00 0x1234 0x00 0x4321 0x1000>;
         hotpluggable;
     };
+
+    reserved-memory {
+        #address-cells = <0x01>;
+        #size-cells = <0x01>;
+        ranges;
+
+        shared {
+            reusable;
+            size = <0x4000000>;
+            alignment = <0x2000>;
+        };
+
+        foo@78000000 {
+            reg = <0x78000000 0x800000>;
+        };
+    };
 };

tests/dts/test_pretty_print.dts

@@ -258,6 +258,43 @@ fn memory() {
     );
 }
 
+#[test]
+fn reserved_memory() {
+    let dtb = include_bytes!("dtb/test_pretty_print.dtb");
+    let fdt = Fdt::new(dtb).unwrap();
+
+    let reserved = fdt.reserved_memory().unwrap().collect::<Vec<_>>();
+
+    assert!(reserved[0].reg().unwrap().is_none());
+    assert_eq!(
+        reserved[0]
+            .size()
+            .unwrap()
+            .unwrap()
+            .to_int::<u32>()
+            .unwrap(),
+        0x400_0000
+    );
+    assert_eq!(
+        reserved[0]
+            .alignment()
+            .unwrap()
+            .unwrap()
+            .to_int::<u32>()
+            .unwrap(),
+        0x2000
+    );
+    assert!(reserved[0].reusable());
+
+    assert!(reserved[1].size().unwrap().is_none());
+    assert!(reserved[1].alignment().unwrap().is_none());
+    assert!(!reserved[1].reusable());
+    let reg = reserved[1].reg().unwrap().unwrap().collect::<Vec<_>>();
+    assert_eq!(reg.len(), 1);
+    assert_eq!(reg[0].address::<u32>().unwrap(), 0x7800_0000);
+    assert_eq!(reg[0].size::<u32>().unwrap(), 0x80_0000);
+}
+
 #[macro_export]
 macro_rules! load_dtb_dts_pair {
     ($name:expr) => {