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# Copyright (c) 2019, Nordic Semiconductor
# SPDX-License-Identifier: BSD-3-Clause
# Tip: You can view just the documentation with 'pydoc3 devicetree.dtlib'
A library for extracting information from .dts (devicetree) files. See the
documentation for the DT and Node classes for more information.
The top-level entry point of the library is the DT class. DT.__init__() takes a
.dts file to parse and a list of directories to search for any /include/d
import collections
import enum
import errno
import os
import re
import string
import sys
import textwrap
from typing import Any, Dict, Iterable, List, \
NamedTuple, NoReturn, Optional, Tuple, Union
# NOTE: tests/ is the test suite for this library.
class DTError(Exception):
"Exception raised for devicetree-related errors"
class Node:
Represents a node in the devicetree ('node-name { ... };').
These attributes are available on Node instances:
The name of the node (a string).
The portion after the '@' in the node's name, or the empty string if the
name has no '@' in it.
Note that this is a string. Run int(node.unit_addr, 16) to get an
A collections.OrderedDict that maps the properties defined on the node to
their values. 'props' is indexed by property name (a string), and values
are Property objects.
To convert property values to Python numbers or strings, use
dtlib.to_num(), dtlib.to_nums(), or dtlib.to_string().
Property values are represented as 'bytes' arrays to support the full
generality of DTS, which allows assignments like
x = "foo", < 0x12345678 >, [ 9A ];
This gives x the value b"foo\0\x12\x34\x56\x78\x9A". Numbers in DTS are
stored in big-endian format.
A collections.OrderedDict containing the subnodes of the node, indexed by
A list with all labels pointing to the node, in the same order as the
labels appear, but with duplicates removed.
'label_1: label_2: node { ... };' gives 'labels' the value
["label_1", "label_2"].
The parent Node of the node. 'None' for the root node.
The path to the node as a string, e.g. "/foo/bar".
The DT instance this node belongs to.
# Public interface
def __init__(self, name: str, parent: Optional['Node'], dt: 'DT'):
Node constructor. Not meant to be called directly by clients.
""" = name
self.parent = parent
self.dt = dt
if name.count("@") > 1:
dt._parse_error("multiple '@' in node name")
if not name == "/":
for char in name:
if char not in _nodename_chars:
dt._parse_error(f"{self.path}: bad character '{char}' "
"in node name")
self.props: Dict[str, 'Property'] = collections.OrderedDict()
self.nodes: Dict[str, 'Node'] = collections.OrderedDict()
self.labels: List[str] = []
self._omit_if_no_ref = False
self._is_referenced = False
def unit_addr(self) -> str:
See the class documentation.
def path(self) -> str:
See the class documentation.
node_names = []
cur = self
while cur.parent:
cur = cur.parent
return "/" + "/".join(reversed(node_names))
def node_iter(self) -> Iterable['Node']:
Returns a generator for iterating over the node and its children,
For example, this will iterate over all nodes in the tree (like
for node in dt.root.node_iter():
yield self
for node in self.nodes.values():
yield from node.node_iter()
def _get_prop(self, name: str) -> 'Property':
# Returns the property named 'name' on the node, creating it if it
# doesn't already exist
prop = self.props.get(name)
if not prop:
prop = Property(self, name)
self.props[name] = prop
return prop
def _del(self) -> None:
# Removes the node from the tree
self.parent.nodes.pop( # type: ignore
def __str__(self):
Returns a DTS representation of the node. Called automatically if the
node is print()ed.
s = "".join(label + ": " for label in self.labels)
s += f"{} {{\n"
for prop in self.props.values():
s += "\t" + str(prop) + "\n"
for child in self.nodes.values():
s += textwrap.indent(child.__str__(), "\t") + "\n"
s += "};"
return s
def __repr__(self):
Returns some information about the Node instance. Called automatically
if the Node instance is evaluated.
return f"<Node {self.path} in '{self.dt.filename}'>"
# See Property.type
class Type(enum.IntEnum):
NUM = 2
NUMS = 3
PATH = 6
class _MarkerType(enum.IntEnum):
# Types of markers in property values
# References
PATH = 0 # &foo
PHANDLE = 1 # <&foo>
LABEL = 2 # foo: <1 2 3>
# Start of data blocks of specific type
UINT8 = 3 # [00 01 02] (and also used for /incbin/)
UINT16 = 4 # /bits/ 16 <1 2 3>
UINT32 = 5 # <1 2 3>
UINT64 = 6 # /bits/ 64 <1 2 3>
STRING = 7 # "foo"
class Property:
Represents a property ('x = ...').
These attributes are available on Property instances:
The name of the property (a string).
The value of the property, as a 'bytes' string. Numbers are stored in
big-endian format, and strings are null-terminated. Putting multiple
comma-separated values in an assignment (e.g., 'x = < 1 >, "foo"') will
concatenate the values.
See the to_*() methods for converting the value to other types.
The type of the property, inferred from the syntax used in the
assignment. This is one of the following constants (with example
Assignment | Property.type
foo; | dtlib.Type.EMPTY
foo = []; | dtlib.Type.BYTES
foo = [01 02]; | dtlib.Type.BYTES
foo = /bits/ 8 <1>; | dtlib.Type.BYTES
foo = <1>; | dtlib.Type.NUM
foo = <>; | dtlib.Type.NUMS
foo = <1 2 3>; | dtlib.Type.NUMS
foo = <1 2>, <3>; | dtlib.Type.NUMS
foo = "foo"; | dtlib.Type.STRING
foo = "foo", "bar"; | dtlib.Type.STRINGS
foo = <&l>; | dtlib.Type.PHANDLE
foo = <&l1 &l2 &l3>; | dtlib.Type.PHANDLES
foo = <&l1 &l2>, <&l3>; | dtlib.Type.PHANDLES
foo = <&l1 1 2 &l2 3 4>; | dtlib.Type.PHANDLES_AND_NUMS
foo = <&l1 1 2>, <&l2 3 4>; | dtlib.Type.PHANDLES_AND_NUMS
foo = &l; | dtlib.Type.PATH
*Anything else* | dtlib.Type.COMPOUND
*Anything else* includes properties mixing phandle (<&label>) and node
path (&label) references with other data.
Data labels in the property value do not influence the type.
A list with all labels pointing to the property, in the same order as the
labels appear, but with duplicates removed.
'label_1: label2: x = ...' gives 'labels' the value
{"label_1", "label_2"}.
A dictionary that maps any labels within the property's value to their
offset, in bytes. For example, 'x = < 0 label_1: 1 label_2: >' gives
'offset_labels' the value {"label_1": 4, "label_2": 8}.
Iteration order will match the order of the labels on Python versions
that preserve dict insertion order.
The Node the property is on.
# Public interface
def __init__(self, node: Node, name: str):
if "@" in name:
node.dt._parse_error("'@' is only allowed in node names") = name
self.node = node
self.value = b""
self.labels: List[str] = []
self._label_offset_lst: List[Tuple[str, int]] = []
# We have to wait to set this until later, when we've got
# the entire tree.
self.offset_labels: Dict[str, int] = {}
# A list of [offset, label, type] lists (sorted by offset),
# giving the locations of references within the value. 'type'
# is either _MarkerType.PATH, for a node path reference,
# _MarkerType.PHANDLE, for a phandle reference, or
# _MarkerType.LABEL, for a label on/within data. Node paths
# and phandles need to be patched in after parsing.
self._markers: List[List] = []
def to_num(self, signed=False) -> int:
Returns the value of the property as a number.
Raises DTError if the property was not assigned with this syntax (has
Property.type Type.NUM):
foo = < 1 >;
signed (default: False):
If True, the value will be interpreted as signed rather than
if self.type is not Type.NUM:
_err("expected property '{0}' on {1} in {2} to be assigned with "
"'{0} = < (number) >;', not '{3}'"
.format(, self.node.path, self.node.dt.filename,
return int.from_bytes(self.value, "big", signed=signed)
def to_nums(self, signed=False) -> List[int]:
Returns the value of the property as a list of numbers.
Raises DTError if the property was not assigned with this syntax (has
Property.type Type.NUM or Type.NUMS):
foo = < 1 2 ... >;
signed (default: False):
If True, the values will be interpreted as signed rather than
if self.type not in (Type.NUM, Type.NUMS):
_err("expected property '{0}' on {1} in {2} to be assigned with "
"'{0} = < (number) (number) ... >;', not '{3}'"
.format(, self.node.path, self.node.dt.filename,
return [int.from_bytes(self.value[i:i + 4], "big", signed=signed)
for i in range(0, len(self.value), 4)]
def to_bytes(self) -> bytes:
Returns the value of the property as a raw 'bytes', like
Property.value, except with added type checking.
Raises DTError if the property was not assigned with this syntax (has
Property.type Type.BYTES):
foo = [ 01 ... ];
if self.type is not Type.BYTES:
_err("expected property '{0}' on {1} in {2} to be assigned with "
"'{0} = [ (byte) (byte) ... ];', not '{3}'"
.format(, self.node.path, self.node.dt.filename,
return self.value
def to_string(self) -> str:
Returns the value of the property as a string.
Raises DTError if the property was not assigned with this syntax (has
Property.type Type.STRING):
foo = "string";
This function might also raise UnicodeDecodeError if the string is
not valid UTF-8.
if self.type is not Type.STRING:
_err("expected property '{0}' on {1} in {2} to be assigned with "
"'{0} = \"string\";', not '{3}'"
.format(, self.node.path, self.node.dt.filename,
ret = self.value.decode("utf-8")[:-1] # Strip null
except UnicodeDecodeError:
_err(f"value of property '{}' ({self.value!r}) "
f"on {self.node.path} in {self.node.dt.filename} "
"is not valid UTF-8")
return ret # The separate 'return' appeases the type checker.
def to_strings(self) -> List[str]:
Returns the value of the property as a list of strings.
Raises DTError if the property was not assigned with this syntax (has
Property.type Type.STRING or Type.STRINGS):
foo = "string", "string", ... ;
Also raises DTError if any of the strings are not valid UTF-8.
if self.type not in (Type.STRING, Type.STRINGS):
_err("expected property '{0}' on {1} in {2} to be assigned with "
"'{0} = \"string\", \"string\", ... ;', not '{3}'"
.format(, self.node.path, self.node.dt.filename,
ret = self.value.decode("utf-8").split("\0")[:-1]
except UnicodeDecodeError:
_err(f"value of property '{}' ({self.value!r}) "
f"on {self.node.path} in {self.node.dt.filename} "
"is not valid UTF-8")
return ret # The separate 'return' appeases the type checker.
def to_node(self) -> Node:
Returns the Node the phandle in the property points to.
Raises DTError if the property was not assigned with this syntax (has
Property.type Type.PHANDLE).
foo = < &bar >;
if self.type is not Type.PHANDLE:
_err("expected property '{0}' on {1} in {2} to be assigned with "
"'{0} = < &foo >;', not '{3}'"
.format(, self.node.path, self.node.dt.filename,
return self.node.dt.phandle2node[int.from_bytes(self.value, "big")]
def to_nodes(self) -> List[Node]:
Returns a list with the Nodes the phandles in the property point to.
Raises DTError if the property value contains anything other than
phandles. All of the following are accepted:
foo = < >
foo = < &bar >;
foo = < &bar &baz ... >;
foo = < &bar ... >, < &baz ... >;
def type_ok():
if self.type in (Type.PHANDLE, Type.PHANDLES):
return True
# Also accept 'foo = < >;'
return self.type is Type.NUMS and not self.value
if not type_ok():
_err("expected property '{0}' on {1} in {2} to be assigned with "
"'{0} = < &foo &bar ... >;', not '{3}'"
.format(, self.node.path,
self.node.dt.filename, self))
return [self.node.dt.phandle2node[int.from_bytes(self.value[i:i + 4],
for i in range(0, len(self.value), 4)]
def to_path(self) -> Node:
Returns the Node referenced by the path stored in the property.
Raises DTError if the property was not assigned with either of these
syntaxes (has Property.type Type.PATH or Type.STRING):
foo = &bar;
foo = "/bar";
For the second case, DTError is raised if the path does not exist.
if self.type not in (Type.PATH, Type.STRING):
_err("expected property '{0}' on {1} in {2} to be assigned with "
"either '{0} = &foo' or '{0} = \"/path/to/node\"', not '{3}'"
.format(, self.node.path, self.node.dt.filename,
path = self.value.decode("utf-8")[:-1]
except UnicodeDecodeError:
_err(f"value of property '{}' ({self.value!r}) "
f"on {self.node.path} in {self.node.dt.filename} "
"is not valid UTF-8")
ret = self.node.dt.get_node(path)
except DTError:
_err(f"property '{}' on {self.node.path} in "
f"{self.node.dt.filename} points to the non-existent node "
return ret # The separate 'return' appeases the type checker.
def type(self) -> int:
See the class docstring.
# Data labels (e.g. 'foo = label: <3>') are irrelevant, so filter them
# out
types = [marker[1] for marker in self._markers
if marker[1] != _MarkerType.LABEL]
if not types:
return Type.EMPTY
if types == [_MarkerType.UINT8]:
return Type.BYTES
if types == [_MarkerType.UINT32]:
return Type.NUM if len(self.value) == 4 else Type.NUMS
# Treat 'foo = <1 2 3>, <4 5>, ...' as Type.NUMS too
if set(types) == {_MarkerType.UINT32}:
return Type.NUMS
if set(types) == {_MarkerType.STRING}:
return Type.STRING if len(types) == 1 else Type.STRINGS
if types == [_MarkerType.PATH]:
return Type.PATH
if types == [_MarkerType.UINT32, _MarkerType.PHANDLE] and \
len(self.value) == 4:
return Type.PHANDLE
if set(types) == {_MarkerType.UINT32, _MarkerType.PHANDLE}:
if len(self.value) == 4*types.count(_MarkerType.PHANDLE):
# Array with just phandles in it
return Type.PHANDLES
# Array with both phandles and numbers
return Type.COMPOUND
def __str__(self):
s = "".join(label + ": " for label in self.labels) +
if not self.value:
return s + ";"
s += " ="
for i, (pos, marker_type, ref) in enumerate(self._markers):
if i < len(self._markers) - 1:
next_marker = self._markers[i + 1]
next_marker = None
# End of current marker
end = next_marker[0] if next_marker else len(self.value)
if marker_type is _MarkerType.STRING:
# end - 1 to strip off the null terminator
s += f' "{_decode_and_escape(self.value[pos:end - 1])}"'
if end != len(self.value):
s += ","
elif marker_type is _MarkerType.PATH:
s += " &" + ref
if end != len(self.value):
s += ","
# <> or []
if marker_type is _MarkerType.LABEL:
s += f" {ref}:"
elif marker_type is _MarkerType.PHANDLE:
s += " &" + ref
pos += 4
# Subtle: There might be more data between the phandle and
# the next marker, so we can't 'continue' here
else: # marker_type is _MarkerType.UINT*
elm_size = _TYPE_TO_N_BYTES[marker_type]
s += _N_BYTES_TO_START_STR[elm_size]
while pos != end:
num = int.from_bytes(self.value[pos:pos + elm_size],
if elm_size == 1:
s += f" {num:02X}"
s += f" {hex(num)}"
pos += elm_size
if pos != 0 and \
(not next_marker or
next_marker[1] not in (_MarkerType.PHANDLE, _MarkerType.LABEL)):
s += _N_BYTES_TO_END_STR[elm_size]
if pos != len(self.value):
s += ","
return s + ";"
def __repr__(self):
return f"<Property '{}' at '{self.node.path}' in " \
# Internal functions
def _add_marker(self, marker_type: _MarkerType, data: Any = None):
# Helper for registering markers in the value that are processed after
# parsing. See _fixup_props(). 'marker_type' identifies the type of
# marker, and 'data' has any optional data associated with the marker.
# len(self.value) gives the current offset. This function is called
# while the value is built. We use a list instead of a tuple to be able
# to fix up offsets later (they might increase if the value includes
# path references, e.g. 'foo = &bar, <3>;', which are expanded later).
self._markers.append([len(self.value), marker_type, data])
# For phandle references, add a dummy value with the same length as a
# phandle. This is handy for the length check in _register_phandles().
if marker_type is _MarkerType.PHANDLE:
self.value += b"\0\0\0\0"
class _T(enum.IntEnum):
# Token IDs used by the DT lexer.
# These values must be contiguous and start from 1.
LINE = 2
DTS_V1 = 4
BITS = 7
LABEL = 11
REF = 13
SKIP = 15
EOF = 16
# These values must be larger than the above contiguous range.
NUM = 17
MISC = 19
BYTE = 20
BAD = 21
class _FileStackElt(NamedTuple):
# Used for maintaining the /include/ stack.
filename: str
lineno: int
contents: str
pos: int
_TokVal = Union[int, str]
class _Token(NamedTuple):
id: int
val: _TokVal
def __repr__(self):
id_repr = _T(
return f'Token(id=_T.{id_repr}, val={repr(self.val)})'
class DT:
Represents a devicetree parsed from a .dts file (or from many files, if the
.dts file /include/s other files). Creating many instances of this class is
fine. The library has no global state.
These attributes are available on DT instances:
A Node instance representing the root (/) node.
A dictionary that maps maps alias strings (from /aliases) to Node
A dictionary that maps each node label (a string) to the Node instance
for the node.
A dictionary that maps each property label (a string) to a Property
A dictionary that maps each label (a string) within a property value
(e.g., 'x = label_1: < 1 label2: 2 >;') to a (prop, offset) tuple, where
'prop' is a Property instance and 'offset' the byte offset (0 for label_1
and 4 for label_2 in the example).
A dictionary that maps each phandle (a number) to a Node instance.
A list of (labels, address, length) tuples for the /memreserve/s in the
.dts file, in the same order as they appear in the file.
'labels' is a possibly empty set with all labels preceding the memreserve
(e.g., 'label1: label2: /memreserve/ ...'). 'address' and 'length' are
The filename passed to the DT constructor.
# Public interface
def __init__(self, filename: str, include_path: Iterable[str] = (),
force: bool = False):
Parses a DTS file to create a DT instance. Raises OSError if 'filename'
can't be opened, and DTError for any parse errors.
Path to the .dts file to parse.
An iterable (e.g. list or tuple) containing paths to search for
/include/d and /incbin/'d files. By default, files are only looked up
relative to the .dts file that contains the /include/ or /incbin/.
Try not to raise DTError even if the input tree has errors.
For experimental use; results not guaranteed.
self.filename = filename
self._include_path = list(include_path)
self._force = force
with open(filename, encoding="utf-8") as f:
self._file_contents =
self._tok_i = self._tok_end_i = 0
self._filestack: List[_FileStackElt] = []
self.alias2node: Dict[str, Node] = {}
self._lexer_state: int = _DEFAULT
self._saved_token: Optional[_Token] = None
self._lineno: int = 1
self._root: Optional[Node] = None
def root(self) -> Node:
See the class documentation.
# This is necessary because mypy can't tell that we never
# treat self._root as a non-None value until it's initialized
# properly in _parse_dt().
return self._root # type: ignore
def get_node(self, path: str) -> Node:
Returns the Node instance for the node with path or alias 'path' (a
string). Raises DTError if the path or alias doesn't exist.
For example, both dt.get_node("/foo/bar") and dt.get_node("bar-alias")
will return the 'bar' node below:
/ {
foo {
bar_label: bar {
baz {
aliases {
bar-alias = &bar-label;
Fetching subnodes via aliases is supported:
dt.get_node("bar-alias/baz") returns the 'baz' node.
if path.startswith("/"):
return _root_and_path_to_node(self.root, path, path)
# Path does not start with '/'. First component must be an alias.
alias, _, rest = path.partition("/")
if alias not in self.alias2node:
_err(f"no alias '{alias}' found -- did you forget the leading "
"'/' in the node path?")
return _root_and_path_to_node(self.alias2node[alias], rest, path)
def has_node(self, path: str) -> bool:
Returns True if the path or alias 'path' exists. See Node.get_node().
return True
except DTError:
return False
def node_iter(self) -> Iterable[Node]:
Returns a generator for iterating over all nodes in the devicetree.
For example, this will print the name of each node that has a property
called 'foo':
for node in dt.node_iter():
if "foo" in node.props:
yield from self.root.node_iter()
def __str__(self):
Returns a DTS representation of the devicetree. Called automatically if
the DT instance is print()ed.
s = "/dts-v1/;\n\n"
if self.memreserves:
for labels, address, offset in self.memreserves:
# List the labels in a consistent order to help with testing
for label in labels:
s += f"{label}: "
s += f"/memreserve/ {address:#018x} {offset:#018x};\n"
s += "\n"
return s + str(self.root)
def __repr__(self):
Returns some information about the DT instance. Called automatically if
the DT instance is evaluated.
return f"DT(filename='{self.filename}', " \
# Parsing
def _parse_dt(self):
# Top-level parsing loop
while True:
tok = self._next_token()
if tok.val == "/":
# '/ { ... };', the root node
if not self._root:
self._root = Node(name="/", parent=None, dt=self)
elif in (_T.LABEL, _T.REF):
# '&foo { ... };' or 'label: &foo { ... };'. The C tools only
# support a single label here too.
if == _T.LABEL:
label = tok.val
tok = self._next_token()
if != _T.REF:
self._parse_error("expected label reference (&foo)")
label = None
node = self._ref2node(tok.val)
except DTError as e:
node = self._parse_node(node)
if label:
_append_no_dup(node.labels, label)
elif == _T.DEL_NODE:
elif == _T.OMIT_IF_NO_REF:
self._next_ref2node()._omit_if_no_ref = True
elif == _T.EOF:
if not self._root:
self._parse_error("no root node defined")
self._parse_error("expected '/' or label reference (&foo)")
def _parse_header(self):
# Parses /dts-v1/ (expected) and /plugin/ (unsupported) at the start of
# files. There may be multiple /dts-v1/ at the start of a file.
has_dts_v1 = False
while self._peek_token().id == _T.DTS_V1:
has_dts_v1 = True
# /plugin/ always comes after /dts-v1/
if self._peek_token().id == _T.PLUGIN:
self._parse_error("/plugin/ is not supported")
if not has_dts_v1:
self._parse_error("expected '/dts-v1/;' at start of file")
def _parse_memreserves(self):
# Parses /memreserve/, which appears after /dts-v1/
self.memreserves = []
while True:
# Labels before /memreserve/
labels = []
while self._peek_token().id == _T.LABEL:
_append_no_dup(labels, self._next_token().val)
if self._peek_token().id == _T.MEMRESERVE:
(labels, self._eval_prim(), self._eval_prim()))
elif labels:
self._parse_error("expected /memreserve/ after labels at "
"beginning of file")
def _parse_node(self, node):
# Parses the '{ ... };' part of 'node-name { ... };'. Returns the new
# Node.
while True:
labels, omit_if_no_ref = self._parse_propnode_labels()
tok = self._next_token()
if self._peek_token().val == "{":
# '<tok> { ...', expect node
# Fetch the existing node if it already exists. This
# happens when overriding nodes.
child = node.nodes.get(tok.val) or \
Node(name=tok.val, parent=node, dt=self)
for label in labels:
_append_no_dup(child.labels, label)
if omit_if_no_ref:
child._omit_if_no_ref = True
node.nodes[] = child
# Not '<tok> { ...', expect property assignment
if omit_if_no_ref:
"/omit-if-no-ref/ can only be used on nodes")
prop = node._get_prop(tok.val)
if self._check_token("="):
elif not self._check_token(";"):
# ';' is for an empty property, like 'foo;'
self._parse_error("expected '{', '=', or ';'")
for label in labels:
_append_no_dup(prop.labels, label)
elif == _T.DEL_NODE:
tok2 = self._next_token()
self._parse_error("expected node name")
if tok2.val in node.nodes:
elif == _T.DEL_PROP:
tok2 = self._next_token()
self._parse_error("expected property name")
node.props.pop(tok2.val, None)
elif tok.val == "}":
return node
self._parse_error("expected node name, property name, or '}'")
def _parse_propnode_labels(self):
# _parse_node() helpers for parsing labels and /omit-if-no-ref/s before
# nodes and properties. Returns a (<label list>, <omit-if-no-ref bool>)
# tuple.
labels = []
omit_if_no_ref = False
while True:
tok = self._peek_token()
if == _T.LABEL:
_append_no_dup(labels, tok.val)
elif == _T.OMIT_IF_NO_REF:
omit_if_no_ref = True
elif (labels or omit_if_no_ref) and != _T.PROPNODENAME:
# Got something like 'foo: bar: }'
self._parse_error("expected node or property name")
return labels, omit_if_no_ref
def _parse_assignment(self, prop):
# Parses the right-hand side of property assignment
# prop:
# 'Property' instance being assigned
# Remove any old value, path/phandle references, and in-value labels,
# in case the property value is being overridden
prop.value = b""
prop._markers = []
while True:
# Parse labels before the value (e.g., '..., label: < 0 >')
tok = self._next_token()
if tok.val == "<":
self._parse_cells(prop, 4)
elif == _T.BITS:
n_bits = self._expect_num()
if n_bits not in {8, 16, 32, 64}:
self._parse_error("expected 8, 16, 32, or 64")
self._parse_cells(prop, n_bits//8)
elif tok.val == "[":
elif == _T.STRING:
prop.value += self._unescape(tok.val.encode("utf-8")) + b"\0"
elif == _T.REF:
prop._add_marker(_MarkerType.PATH, tok.val)
elif == _T.INCBIN:
self._parse_error("malformed value")
# Parse labels after the value (e.g., '< 0 > label:, ...')
tok = self._next_token()
if tok.val == ";":
if tok.val == ",":
self._parse_error("expected ';' or ','")
def _parse_cells(self, prop, n_bytes):
# Parses '<...>'
while True:
tok = self._peek_token()
if == _T.REF:
if n_bytes != 4:
self._parse_error("phandle references are only allowed in "
"arrays with 32-bit elements")
prop._add_marker(_MarkerType.PHANDLE, tok.val)
elif == _T.LABEL:
prop._add_marker(_MarkerType.LABEL, tok.val)
elif self._check_token(">"):
# Literal value
num = self._eval_prim()
prop.value += num.to_bytes(n_bytes, "big")
except OverflowError:
# Try again as a signed number, in case it's negative
prop.value += num.to_bytes(n_bytes, "big", signed=True)
except OverflowError:
f"{num} does not fit in {8*n_bytes} bits")
def _parse_bytes(self, prop):
# Parses '[ ... ]'
while True:
tok = self._next_token()
if == _T.BYTE:
prop.value += tok.val.to_bytes(1, "big")
elif == _T.LABEL:
prop._add_marker(_MarkerType.LABEL, tok.val)
elif tok.val == "]":
self._parse_error("expected two-digit byte or ']'")
def _parse_incbin(self, prop):
# Parses
# /incbin/ ("filename")
# and
# /incbin/ ("filename", <offset>, <size>)
tok = self._next_token()
if != _T.STRING:
self._parse_error("expected quoted filename")
filename = tok.val
tok = self._next_token()
if tok.val == ",":
offset = self._eval_prim()
size = self._eval_prim()
if tok.val != ")":
self._parse_error("expected ',' or ')'")
offset = None
with self._open(filename, "rb") as f:
if offset is None:
prop.value +=
prop.value +=
except OSError as e:
self._parse_error(f"could not read '{filename}': {e}")
def _parse_value_labels(self, prop):
# _parse_assignment() helper for parsing labels before/after each
# comma-separated value
while True:
tok = self._peek_token()
if != _T.LABEL:
prop._add_marker(_MarkerType.LABEL, tok.val)
def _node_phandle(self, node):
# Returns the phandle for Node 'node', creating a new phandle if the
# node has no phandle, and fixing up the value for existing
# self-referential phandles (which get set to b'\0\0\0\0' initially).
# Self-referential phandles must be rewritten instead of recreated, so
# that labels are preserved.
if "phandle" in node.props:
phandle_prop = node.props["phandle"]
phandle_prop = Property(node, "phandle")
phandle_prop._add_marker(_MarkerType.UINT32) # For displaying
phandle_prop.value = b'\0\0\0\0'
if phandle_prop.value == b'\0\0\0\0':
phandle_i = 1
while phandle_i in self.phandle2node:
phandle_i += 1
self.phandle2node[phandle_i] = node
phandle_prop.value = phandle_i.to_bytes(4, "big")
node.props["phandle"] = phandle_prop
return phandle_prop.value
# Expression evaluation
def _eval_prim(self):
tok = self._peek_token()
if in (_T.NUM, _T.CHAR_LITERAL):
return self._next_token().val
tok = self._next_token()
if tok.val != "(":
self._parse_error("expected number or parenthesized expression")
val = self._eval_ternary()
return val
def _eval_ternary(self):
val = self._eval_or()
if self._check_token("?"):
if_val = self._eval_ternary()
else_val = self._eval_ternary()
return if_val if val else else_val
return val
def _eval_or(self):
val = self._eval_and()
while self._check_token("||"):
val = 1 if self._eval_and() or val else 0
return val
def _eval_and(self):
val = self._eval_bitor()
while self._check_token("&&"):
val = 1 if self._eval_bitor() and val else 0
return val
def _eval_bitor(self):
val = self._eval_bitxor()
while self._check_token("|"):
val |= self._eval_bitxor()
return val
def _eval_bitxor(self):
val = self._eval_bitand()
while self._check_token("^"):
val ^= self._eval_bitand()
return val
def _eval_bitand(self):
val = self._eval_eq()
while self._check_token("&"):
val &= self._eval_eq()
return val
def _eval_eq(self):
val = self._eval_rela()
while True:
if self._check_token("=="):
val = 1 if val == self._eval_rela() else 0
elif self._check_token("!="):
val = 1 if val != self._eval_rela() else 0
return val
def _eval_rela(self):
val = self._eval_shift()
while True:
if self._check_token("<"):
val = 1 if val < self._eval_shift() else 0
elif self._check_token(">"):
val = 1 if val > self._eval_shift() else 0
elif self._check_token("<="):
val = 1 if val <= self._eval_shift() else 0
elif self._check_token(">="):
val = 1 if val >= self._eval_shift() else 0
return val
def _eval_shift(self):
val = self._eval_add()
while True:
if self._check_token("<<"):
val <<= self._eval_add()
elif self._check_token(">>"):
val >>= self._eval_add()
return val
def _eval_add(self):
val = self._eval_mul()
while True:
if self._check_token("+"):
val += self._eval_mul()
elif self._check_token("-"):
val -= self._eval_mul()
return val
def _eval_mul(self):
val = self._eval_unary()
while True:
if self._check_token("*"):
val *= self._eval_unary()
elif self._check_token("/"):
denom = self._eval_unary()
if not denom:
self._parse_error("division by zero")
val //= denom
elif self._check_token("%"):
denom = self._eval_unary()
if not denom:
self._parse_error("division by zero")
val %= denom
return val
def _eval_unary(self):
if self._check_token("-"):
return -self._eval_unary()
if self._check_token("~"):
return ~self._eval_unary()
if self._check_token("!"):
return 0 if self._eval_unary() else 1
return self._eval_prim()
# Lexing
def _check_token(self, val):
if self._peek_token().val == val:
return True
return False
def _peek_token(self):
if not self._saved_token:
self._saved_token = self._next_token()
return self._saved_token
def _next_token(self):
if self._saved_token:
tmp = self._saved_token
self._saved_token = None
return tmp
while True:
tok_id = None
match = _token_re.match(self._file_contents, self._tok_end_i)
if match:
tok_id = match.lastindex
if tok_id == _T.CHAR_LITERAL:
val = self._unescape("utf-8"))
if len(val) != 1:
self._parse_error("character literals must be length 1")
tok_val = ord(val)
tok_val =
elif self._lexer_state is _DEFAULT:
match = _num_re.match(self._file_contents, self._tok_end_i)
if match:
tok_id = _T.NUM
num_s =
tok_val = int(num_s,
16 if num_s.startswith(("0x", "0X")) else
8 if num_s[0] == "0" else
elif self._lexer_state is _EXPECT_PROPNODENAME:
match = _propnodename_re.match(self._file_contents,
if match:
tok_val =
self._lexer_state = _DEFAULT
else: # self._lexer_state is _EXPECT_BYTE
match = _byte_re.match(self._file_contents, self._tok_end_i)
if match:
tok_id = _T.BYTE
tok_val = int(, 16)
if not tok_id:
match = _misc_re.match(self._file_contents, self._tok_end_i)
if match:
tok_id = _T.MISC
tok_val =
self._tok_i = self._tok_end_i
# Could get here due to a node/property naming appearing in
# an unexpected context as well as for bad characters in
# files. Generate a token for it so that the error can
# trickle up to some context where we can give a more
# helpful error message.
return _Token(_T.BAD, "<unknown token>")
self._tok_i = match.start()
self._tok_end_i = match.end()
if tok_id == _T.SKIP:
self._lineno += tok_val.count("\n")
# /include/ is handled in the lexer in the C tools as well, and can
# appear anywhere
if tok_id == _T.INCLUDE:
# Can have newlines between /include/ and the filename
self._lineno += tok_val.count("\n")
# Do this manual extraction instead of doing it in the regex so
# that we can properly count newlines
filename = tok_val[tok_val.find('"') + 1:-1]
if tok_id == _T.LINE:
# #line directive
self._lineno = int(tok_val.split()[0]) - 1
self.filename = tok_val[tok_val.find('"') + 1:-1]
if tok_id == _T.EOF:
if self._filestack:
return _Token(_T.EOF, "<EOF>")
# State handling
if tok_id in (_T.DEL_PROP, _T.DEL_NODE, _T.OMIT_IF_NO_REF) or \
tok_val in ("{", ";"):
self._lexer_state = _EXPECT_PROPNODENAME
elif tok_val == "[":
self._lexer_state = _EXPECT_BYTE
elif tok_id in (_T.MEMRESERVE, _T.BITS) or tok_val == "]":
self._lexer_state = _DEFAULT
return _Token(tok_id, tok_val)
def _expect_token(self, tok_val):
# Raises an error if the next token does not have the string value
# 'tok_val'. Returns the token.
tok = self._next_token()
if tok.val != tok_val:
self._parse_error(f"expected '{tok_val}', not '{tok.val}'")
return tok
def _expect_num(self):
# Raises an error if the next token is not a number. Returns the token.
tok = self._next_token()
if != _T.NUM:
self._parse_error("expected number")
return tok.val
def _parse_error(self, s):
# This works out for the first line of the file too, where rfind()
# returns -1
column = self._tok_i - self._file_contents.rfind("\n", 0,
self._tok_i + 1)
_err(f"{self.filename}:{self._lineno} (column {column}): "
f"parse error: {s}")
def _enter_file(self, filename):
# Enters the /include/d file 'filename', remembering the position in
# the /include/ing file for later
_FileStackElt(self.filename, self._lineno,
self._file_contents, self._tok_end_i))
# Handle escapes in filenames, just for completeness
filename = self._unescape(filename.encode("utf-8"))
filename = filename.decode("utf-8")
except UnicodeDecodeError:
self._parse_error("filename is not valid UTF-8")
with self._open(filename, encoding="utf-8") as f:
self._file_contents =
except OSError as e:
# Check for recursive /include/
for i, parent in enumerate(self._filestack):
if filename == parent[0]:
self._parse_error("recursive /include/:\n" + " ->\n".join(
for parent in self._filestack[i:]] +
self.filename =
self._lineno = 1
self._tok_end_i = 0
def _leave_file(self):
# Leaves an /include/d file, returning to the file that /include/d it
self.filename, self._lineno, self._file_contents, self._tok_end_i = \
def _next_ref2node(self):
# Checks that the next token is a label/path reference and returns the
# Node it points to. Only used during parsing, so uses _parse_error()
# on errors to save some code in callers.
label = self._next_token()
if != _T.REF:
"expected label (&foo) or path (&{/foo/bar}) reference")
return self._ref2node(label.val)
except DTError as e:
def _ref2node(self, s):
# Returns the Node the label/path reference 's' points to
if s[0] == "{":
# Path reference (&{/foo/bar})
path = s[1:-1]
if not path.startswith("/"):
_err(f"node path '{path}' does not start with '/'")
# Will raise DTError if the path doesn't exist
return _root_and_path_to_node(self.root, path, path)
# Label reference (&foo).
# label2node hasn't been filled in yet, and using it would get messy
# when nodes are deleted
for node in self.node_iter():
if s in node.labels:
return node
_err(f"undefined node label '{s}'")
# Post-processing
def _register_phandles(self):
# Registers any manually-inserted phandle properties in
# self.phandle2node, so that we can avoid allocating any phandles from
# that set. Also checks the format of the phandles and does misc.
# sanity checking.
self.phandle2node = {}
for node in self.node_iter():
phandle = node.props.get("phandle")
if phandle:
if len(phandle.value) != 4:
_err(f"{node.path}: bad phandle length "
f"({len(phandle.value)}), expected 4 bytes")
is_self_referential = False
for marker in phandle._markers:
_, marker_type, ref = marker
if marker_type is _MarkerType.PHANDLE:
# The phandle's value is itself a phandle reference
if self._ref2node(ref) is node:
# Alright to set a node's phandle equal to its own
# phandle. It'll force a new phandle to be
# allocated even if the node is otherwise
# unreferenced.
is_self_referential = True
_err(f"{node.path}: {} "
"refers to another node")
# Could put on else on the 'for' above too, but keep it
# somewhat readable
if not is_self_referential:
phandle_val = int.from_bytes(phandle.value, "big")
if phandle_val in {0, 0xFFFFFFFF}:
_err(f"{node.path}: bad value {phandle_val:#010x} "
f"for {}")
if phandle_val in self.phandle2node:
_err(f"{node.path}: duplicated phandle {phandle_val:#x} "
"(seen before at "
self.phandle2node[phandle_val] = node
def _fixup_props(self):
# Fills in node path and phandle references in property values, and
# registers labels within values. This must be done after parsing,
# since forwards references are allowed and nodes and properties might
# be deleted.
for node in self.node_iter():
# The tuple() avoids a 'dictionary changed size during iteration'
# error
for prop in tuple(node.props.values()):
# 'prev_pos' and 'pos' are indices in the unpatched
# property value. The result is built up in 'res'.
prev_pos = 0
res = b""
for marker in prop._markers:
pos, marker_type, ref = marker
# Add data before the marker, reading from the unpatched
# property value
res += prop.value[prev_pos:pos]
# Fix the marker offset so that it's correct for the
# patched property value, for later (not used in this
# function). The offset might change due to path
# references, which expand to something like "/foo/bar".
marker[0] = len(res)
if marker_type is _MarkerType.LABEL:
# This is a temporary format so that we can catch
# duplicate references. prop._label_offset_lst is changed
# to a dictionary that maps labels to offsets in
# _register_labels().
_append_no_dup(prop._label_offset_lst, (ref, len(res)))
elif marker_type in (_MarkerType.PATH, _MarkerType.PHANDLE):
# Path or phandle reference
ref_node = self._ref2node(ref)
except DTError as e:
_err(f"{prop.node.path}: {e}")
# For /omit-if-no-ref/
ref_node._is_referenced = True
if marker_type is _MarkerType.PATH:
res += ref_node.path.encode("utf-8") + b'\0'
else: # marker_type is PHANDLE
res += self._node_phandle(ref_node)
# Skip over the dummy phandle placeholder
pos += 4
prev_pos = pos
# Store the final fixed-up value. Add the data after the last
# marker.
prop.value = res + prop.value[prev_pos:]
def _register_aliases(self):
# Registers aliases from the /aliases node in self.alias2node. Also
# checks the format of the alias properties.
# We copy this to self.alias2node at the end to avoid get_node()
# looking up paths via other aliases while verifying aliases
alias2node = {}
alias_re = re.compile("[0-9a-z-]+$")
aliases = self.root.nodes.get("aliases")
if aliases:
for prop in aliases.props.values():
if not alias_re.match(
_err(f"/aliases: alias property name '{}' "
"should include only characters from [0-9a-z-]")
# Property.to_path() checks that the node exists, has
# the right type, etc. Swallow errors for invalid
# aliases with self._force.
alias2node[] = prop.to_path()
except DTError:
if self._force:
self.alias2node = alias2node
def _remove_unreferenced(self):
# Removes any unreferenced nodes marked with /omit-if-no-ref/ from the
# tree
# tuple() is to avoid 'RuntimeError: dictionary changed size during
# iteration' errors
for node in tuple(self.node_iter()):
if node._omit_if_no_ref and not node._is_referenced:
def _register_labels(self):
# Checks for duplicate labels and registers labels in label2node,
# label2prop, and label2prop_offset
label2things = collections.defaultdict(set)
self.label2node = {}
self.label2prop = {}
self.label2prop_offset = {}
# Register all labels and the nodes/props they point to in label2things
for node in self.node_iter():
for label in node.labels:
self.label2node[label] = node
for prop in node.props.values():
for label in prop.labels:
self.label2prop[label] = prop
for label, offset in prop._label_offset_lst:
label2things[label].add((prop, offset))
self.label2prop_offset[label] = (prop, offset)
# See _fixup_props()
prop.offset_labels = dict(prop._label_offset_lst)
for label, things in label2things.items():
if len(things) > 1:
strings = []
for thing in things:
if isinstance(thing, Node):
strings.append(f"on {thing.path}")
elif isinstance(thing, Property):
strings.append(f"on property '{}' "
f"of node {thing.node.path}")
# Label within property value
strings.append("in the value of property "
f"'{thing[0].name}' of node "
# Give consistent error messages to help with testing
_err(f"Label '{label}' appears " + " and ".join(strings))
# Misc.
def _unescape(self, b):
# Replaces backslash escapes in the 'bytes' array 'b'. We can't do this at
# the string level, because the result might not be valid UTF-8 when
# octal/hex escapes are involved.
def sub(match):
esc =
if esc == b"a": return b"\a"
if esc == b"b": return b"\b"
if esc == b"t": return b"\t"
if esc == b"n": return b"\n"
if esc == b"v": return b"\v"
if esc == b"f": return b"\f"
if esc == b"r": return b"\r"
if esc[0] in b"01234567":
# Octal escape
return int(esc, 8).to_bytes(1, "big")
except OverflowError:
self._parse_error("octal escape out of range (> 255)")
if esc[0] == ord("x") and len(esc) > 1:
# Hex escape
return int(esc[1:], 16).to_bytes(1, "big")
# Return <char> as-is for other \<char>
return esc[0].to_bytes(1, "big")
return _unescape_re.sub(sub, b)
def _open(self, filename, mode="r", **kwargs):
# Wrapper around standard Python open(), accepting the same params.
# But searches for a 'filename' file in the directory of the current
# file and the include path.
# The C tools support specifying stdin with '-' too
if filename == "-":
return sys.stdin.buffer if "b" in mode else sys.stdin
# Try the directory of the current file first
dirname = os.path.dirname(self.filename)
return open(os.path.join(dirname, filename), mode, **kwargs)
except OSError as e:
if e.errno != errno.ENOENT:
# Try each directory from the include path
for path in self._include_path:
return open(os.path.join(path, filename), mode, **kwargs)
except OSError as e:
if e.errno != errno.ENOENT:
self._parse_error(f"'{filename}' could not be found")
# Public functions
def to_num(data: bytes, length: Optional[int] = None,
signed: bool = False) -> int:
Converts the 'bytes' array 'data' to a number. The value is expected to be
in big-endian format, which is standard in devicetree.
length (default: None):
The expected length of the value in bytes, as a simple type check. If
None, the length check is skipped.
signed (default: False):
If True, the value will be interpreted as signed rather than unsigned.
if length is not None:
if len(data) != length:
_err(f"{data!r} is {len(data)} bytes long, expected {length}")
return int.from_bytes(data, "big", signed=signed)
def to_nums(data: bytes, length: int = 4, signed: bool = False) -> List[int]:
Like Property.to_nums(), but takes an arbitrary 'bytes' array. The values
are assumed to be in big-endian format, which is standard in devicetree.
if len(data) % length:
_err(f"{data!r} is {len(data)} bytes long, "
f"expected a length that's a a multiple of {length}")
return [int.from_bytes(data[i:i + length], "big", signed=signed)
for i in range(0, len(data), length)]
# Public constants
def _check_is_bytes(data):
if not isinstance(data, bytes):
_err(f"'{data}' has type '{type(data).__name__}', expected 'bytes'")
def _check_length_positive(length):
if length < 1:
_err("'length' must be greater than zero, was " + str(length))
def _append_no_dup(lst, elm):
# Appends 'elm' to 'lst', but only if it isn't already in 'lst'. Lets us
# preserve order, which a set() doesn't.
if elm not in lst:
def _decode_and_escape(b):
# Decodes the 'bytes' array 'b' as UTF-8 and backslash-escapes special
# characters
# Hacky but robust way to avoid double-escaping any '\' spit out by
# 'backslashreplace' bytes.translate() can't map to more than a single
# byte, but str.translate() can map to more than one character, so it's
# nice here. There's probably a nicer way to do this.
return b.decode("utf-8", "surrogateescape") \
.translate(_escape_table) \
.encode("utf-8", "surrogateescape") \
.decode("utf-8", "backslashreplace")
def _root_and_path_to_node(cur, path, fullpath):
# Returns the node pointed at by 'path', relative to the Node 'cur'. For
# example, if 'cur' has path /foo/bar, and 'path' is "baz/qaz", then the
# node with path /foo/bar/baz/qaz is returned. 'fullpath' is the path as
# given in the .dts file, for error messages.
for component in path.split("/"):
# Collapse multiple / in a row, and allow a / at the end
if not component:
if component not in cur.nodes:
_err(f"component '{component}' in path '{fullpath}' "
"does not exist")
cur = cur.nodes[component]
return cur
def _err(msg) -> NoReturn:
raise DTError(msg)
_escape_table = str.maketrans({
"\\": "\\\\",
'"': '\\"',
"\a": "\\a",
"\b": "\\b",
"\t": "\\t",
"\n": "\\n",
"\v": "\\v",
"\f": "\\f",
"\r": "\\r"})
# Lexer states
_num_re = re.compile(r"(0[xX][0-9a-fA-F]+|[0-9]+)(?:ULL|UL|LL|U|L)?")
# A leading \ is allowed property and node names, probably to allow weird node
# names that would clash with other stuff
_propnodename_re = re.compile(r"\\?([a-zA-Z0-9,._+*#?@-]+)")
# Node names are more restrictive than property names.
_nodename_chars = set(string.ascii_letters + string.digits + ',._+-@')
# Misc. tokens that are tried after a property/node name. This is important, as
# there's overlap with the allowed characters in names.
_misc_re = re.compile(
"|".join(re.escape(pat) for pat in (
"==", "!=", "!", "=", ",", ";", "+", "-", "*", "/", "%", "~", "?", ":",
"^", "(", ")", "{", "}", "[", "]", "<<", "<=", "<", ">>", ">=", ">",
"||", "|", "&&", "&")))
_byte_re = re.compile(r"[0-9a-fA-F]{2}")
# Matches a backslash escape within a 'bytes' array. Captures the 'c' part of
# '\c', where c might be a single character or an octal/hex escape.
_unescape_re = re.compile(br'\\([0-7]{1,3}|x[0-9A-Fa-f]{1,2}|.)')
def _init_tokens():
# Builds a (<token 1>)|(<token 2>)|... regex and returns it. The
# way this is constructed makes the token's value as an int appear
# in match.lastindex after a match.
# Each pattern must have exactly one capturing group, which can capture any
# part of the pattern. This makes match.lastindex match the token type.
# _Token.val is based on the captured string.
token_spec = {
_T.INCLUDE: r'(/include/\s*"(?:[^\\"]|\\.)*")',
# #line directive or GCC linemarker
r'^#(?:line)?[ \t]+([0-9]+[ \t]+"(?:[^\\"]|\\.)*")(?:[ \t]+[0-9]+){0,4}',
_T.STRING: r'"((?:[^\\"]|\\.)*)"',
_T.DTS_V1: r"(/dts-v1/)",
_T.PLUGIN: r"(/plugin/)",
_T.MEMRESERVE: r"(/memreserve/)",
_T.BITS: r"(/bits/)",
_T.DEL_PROP: r"(/delete-property/)",
_T.DEL_NODE: r"(/delete-node/)",
_T.OMIT_IF_NO_REF: r"(/omit-if-no-ref/)",
_T.LABEL: r"([a-zA-Z_][a-zA-Z0-9_]*):",
_T.CHAR_LITERAL: r"'((?:[^\\']|\\.)*)'",
_T.REF: r"&([a-zA-Z_][a-zA-Z0-9_]*|{[a-zA-Z0-9,._+*#?@/-]*})",
_T.INCBIN: r"(/incbin/)",
# Whitespace, C comments, and C++ comments
_T.SKIP: r"(\s+|(?:/\*(?:.|\n)*?\*/)|//.*$)",
# Return a token for end-of-file so that the parsing code can
# always assume that there are more tokens when looking
# ahead. This simplifies things.
_T.EOF: r"(\Z)",
# MULTILINE is needed for C++ comments and #line directives
return re.compile("|".join(token_spec[tok_id] for tok_id in
range(1, _T.EOF + 1)),
_token_re = _init_tokens()
_MarkerType.UINT8: 1,
_MarkerType.UINT16: 2,
_MarkerType.UINT32: 4,
_MarkerType.UINT64: 8,
1: _MarkerType.UINT8,
2: _MarkerType.UINT16,
4: _MarkerType.UINT32,
8: _MarkerType.UINT64,
1: " [",
2: " /bits/ 16 <",
4: " <",
8: " /bits/ 64 <",
1: " ]",
2: " >",
4: " >",
8: " >",