214 lines
6.6 KiB
Python
214 lines
6.6 KiB
Python
#!/usr/bin/python
|
|
#
|
|
# Copyright (C) 2016 Google, Inc
|
|
# Written by Simon Glass <sjg@chromium.org>
|
|
#
|
|
# SPDX-License-Identifier: GPL-2.0+
|
|
#
|
|
|
|
import command
|
|
import fdt_util
|
|
import sys
|
|
|
|
# This deals with a device tree, presenting it as a list of Node and Prop
|
|
# objects, representing nodes and properties, respectively.
|
|
#
|
|
# This implementation uses the fdtget tool to access the device tree, so it
|
|
# is not very efficient for larger trees. The tool is called once for each
|
|
# node and property in the tree.
|
|
|
|
class Prop:
|
|
"""A device tree property
|
|
|
|
Properties:
|
|
name: Property name (as per the device tree)
|
|
value: Property value as a string of bytes, or a list of strings of
|
|
bytes
|
|
type: Value type
|
|
"""
|
|
def __init__(self, name, byte_list_str):
|
|
self.name = name
|
|
self.value = None
|
|
if not byte_list_str.strip():
|
|
self.type = fdt_util.TYPE_BOOL
|
|
return
|
|
bytes = [chr(int(byte, 16)) for byte in byte_list_str.strip().split(' ')]
|
|
self.type, self.value = fdt_util.BytesToValue(''.join(bytes))
|
|
|
|
def GetPhandle(self):
|
|
"""Get a (single) phandle value from a property
|
|
|
|
Gets the phandle valuie from a property and returns it as an integer
|
|
"""
|
|
return fdt_util.fdt32_to_cpu(self.value[:4])
|
|
|
|
def Widen(self, newprop):
|
|
"""Figure out which property type is more general
|
|
|
|
Given a current property and a new property, this function returns the
|
|
one that is less specific as to type. The less specific property will
|
|
be ble to represent the data in the more specific property. This is
|
|
used for things like:
|
|
|
|
node1 {
|
|
compatible = "fred";
|
|
value = <1>;
|
|
};
|
|
node1 {
|
|
compatible = "fred";
|
|
value = <1 2>;
|
|
};
|
|
|
|
He we want to use an int array for 'value'. The first property
|
|
suggests that a single int is enough, but the second one shows that
|
|
it is not. Calling this function with these two propertes would
|
|
update the current property to be like the second, since it is less
|
|
specific.
|
|
"""
|
|
if newprop.type < self.type:
|
|
self.type = newprop.type
|
|
|
|
if type(newprop.value) == list and type(self.value) != list:
|
|
self.value = newprop.value
|
|
|
|
if type(self.value) == list and len(newprop.value) > len(self.value):
|
|
val = fdt_util.GetEmpty(self.type)
|
|
while len(self.value) < len(newprop.value):
|
|
self.value.append(val)
|
|
|
|
|
|
class Node:
|
|
"""A device tree node
|
|
|
|
Properties:
|
|
name: Device tree node tname
|
|
path: Full path to node, along with the node name itself
|
|
_fdt: Device tree object
|
|
subnodes: A list of subnodes for this node, each a Node object
|
|
props: A dict of properties for this node, each a Prop object.
|
|
Keyed by property name
|
|
"""
|
|
def __init__(self, fdt, name, path):
|
|
self.name = name
|
|
self.path = path
|
|
self._fdt = fdt
|
|
self.subnodes = []
|
|
self.props = {}
|
|
|
|
def Scan(self):
|
|
"""Scan a node's properties and subnodes
|
|
|
|
This fills in the props and subnodes properties, recursively
|
|
searching into subnodes so that the entire tree is built.
|
|
"""
|
|
for name, byte_list_str in self._fdt.GetProps(self.path).iteritems():
|
|
prop = Prop(name, byte_list_str)
|
|
self.props[name] = prop
|
|
|
|
for name in self._fdt.GetSubNodes(self.path):
|
|
sep = '' if self.path[-1] == '/' else '/'
|
|
path = self.path + sep + name
|
|
node = Node(self._fdt, name, path)
|
|
self.subnodes.append(node)
|
|
|
|
node.Scan()
|
|
|
|
|
|
class Fdt:
|
|
"""Provides simple access to a flat device tree blob.
|
|
|
|
Properties:
|
|
fname: Filename of fdt
|
|
_root: Root of device tree (a Node object)
|
|
"""
|
|
|
|
def __init__(self, fname):
|
|
self.fname = fname
|
|
|
|
def Scan(self):
|
|
"""Scan a device tree, building up a tree of Node objects
|
|
|
|
This fills in the self._root property
|
|
"""
|
|
self._root = Node(self, '/', '/')
|
|
self._root.Scan()
|
|
|
|
def GetRoot(self):
|
|
"""Get the root Node of the device tree
|
|
|
|
Returns:
|
|
The root Node object
|
|
"""
|
|
return self._root
|
|
|
|
def GetSubNodes(self, node):
|
|
"""Returns a list of sub-nodes of a given node
|
|
|
|
Args:
|
|
node: Node name to return children from
|
|
|
|
Returns:
|
|
List of children in the node (each a string node name)
|
|
|
|
Raises:
|
|
CmdError: if the node does not exist.
|
|
"""
|
|
out = command.Output('fdtget', self.fname, '-l', node)
|
|
return out.strip().splitlines()
|
|
|
|
def GetProps(self, node, convert_dashes=False):
|
|
"""Get all properties from a node
|
|
|
|
Args:
|
|
node: full path to node name to look in
|
|
convert_dashes: True to convert - to _ in node names
|
|
|
|
Returns:
|
|
A dictionary containing all the properties, indexed by node name.
|
|
The entries are simply strings - no decoding of lists or numbers
|
|
is done.
|
|
|
|
Raises:
|
|
CmdError: if the node does not exist.
|
|
"""
|
|
out = command.Output('fdtget', self.fname, node, '-p')
|
|
props = out.strip().splitlines()
|
|
props_dict = {}
|
|
for prop in props:
|
|
name = prop
|
|
if convert_dashes:
|
|
prop = re.sub('-', '_', prop)
|
|
props_dict[prop] = self.GetProp(node, name)
|
|
return props_dict
|
|
|
|
def GetProp(self, node, prop, default=None, typespec=None):
|
|
"""Get a property from a device tree.
|
|
|
|
This looks up the given node and property, and returns the value as a
|
|
string,
|
|
|
|
If the node or property does not exist, this will return the default
|
|
value.
|
|
|
|
Args:
|
|
node: Full path to node to look up.
|
|
prop: Property name to look up.
|
|
default: Default value to return if nothing is present in the fdt,
|
|
or None to raise in this case. This will be converted to a
|
|
string.
|
|
typespec: Type character to use (None for default, 's' for string)
|
|
|
|
Returns:
|
|
string containing the property value.
|
|
|
|
Raises:
|
|
CmdError: if the property does not exist and no default is provided.
|
|
"""
|
|
args = [self.fname, node, prop, '-t', 'bx']
|
|
if default is not None:
|
|
args += ['-d', str(default)]
|
|
if typespec is not None:
|
|
args += ['-t%s' % typespec]
|
|
out = command.Output('fdtget', *args)
|
|
return out.strip()
|