import sys
import fdt_util
+import libfdt
# This deals with a device tree, presenting it as an assortment of Node and
# Prop objects, representing nodes and properties, respectively. This file
-# contains the base classes and defines the high-level API. Most of the
-# implementation is in the FdtNormal subclass. See fdt_select.py for how to
-# create an Fdt object.
+# contains the base classes and defines the high-level API. See fdt_select.py
+# for how to create an Fdt object.
+
+# This implementation uses a libfdt Python library to access the device tree,
+# so it is fairly efficient.
# A list of types we support
(TYPE_BYTE, TYPE_INT, TYPE_STRING, TYPE_BOOL) = range(4)
raise ValueError('Error %d: %s: %s' %
(errnum, libfdt.fdt_strerror(errnum), msg))
-class PropBase:
+class Prop:
"""A device tree property
Properties:
bytes
type: Value type
"""
- def __init__(self, node, offset, name):
+ def __init__(self, node, offset, name, bytes):
self._node = node
self._offset = offset
self.name = name
self.value = None
+ self.bytes = str(bytes)
+ if not bytes:
+ self.type = TYPE_BOOL
+ self.value = True
+ return
+ self.type, self.value = self.BytesToValue(bytes)
def GetPhandle(self):
"""Get a (single) phandle value from a property
def GetOffset(self):
"""Get the offset of a property
- This can be implemented by subclasses.
-
Returns:
- The offset of the property (struct fdt_property) within the
- file, or None if not known.
+ The offset of the property (struct fdt_property) within the file
"""
- return None
+ return self._node._fdt.GetStructOffset(self._offset)
-class NodeBase:
+class Node:
"""A device tree node
Properties:
return subnode
return None
+ def Offset(self):
+ """Returns the offset of a node, after checking the cache
+
+ This should be used instead of self._offset directly, to ensure that
+ the cache does not contain invalid offsets.
+ """
+ self._fdt.CheckCache()
+ return self._offset
+
def Scan(self):
- """Scan the subnodes of a node
+ """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.
+ """
+ self.props = self._fdt.GetProps(self)
+
+ offset = libfdt.fdt_first_subnode(self._fdt.GetFdt(), self.Offset())
+ while offset >= 0:
+ sep = '' if self.path[-1] == '/' else '/'
+ name = self._fdt._fdt_obj.get_name(offset)
+ path = self.path + sep + name
+ node = Node(self._fdt, offset, name, path)
+ self.subnodes.append(node)
- This should be implemented by subclasses
+ node.Scan()
+ offset = libfdt.fdt_next_subnode(self._fdt.GetFdt(), offset)
+
+ def Refresh(self, my_offset):
+ """Fix up the _offset for each node, recursively
+
+ Note: This does not take account of property offsets - these will not
+ be updated.
"""
- raise NotImplementedError()
+ if self._offset != my_offset:
+ #print '%s: %d -> %d\n' % (self.path, self._offset, my_offset)
+ self._offset = my_offset
+ offset = libfdt.fdt_first_subnode(self._fdt.GetFdt(), self._offset)
+ for subnode in self.subnodes:
+ subnode.Refresh(offset)
+ offset = libfdt.fdt_next_subnode(self._fdt.GetFdt(), offset)
def DeleteProp(self, prop_name):
"""Delete a property of a node
- This should be implemented by subclasses
+ The property is deleted and the offset cache is invalidated.
Args:
prop_name: Name of the property to delete
+ Raises:
+ ValueError if the property does not exist
"""
- raise NotImplementedError()
+ CheckErr(libfdt.fdt_delprop(self._fdt.GetFdt(), self.Offset(), prop_name),
+ "Node '%s': delete property: '%s'" % (self.path, prop_name))
+ del self.props[prop_name]
+ self._fdt.Invalidate()
class Fdt:
- """Provides simple access to a flat device tree blob.
+ """Provides simple access to a flat device tree blob using libfdts.
Properties:
fname: Filename of fdt
"""
def __init__(self, fname):
self._fname = fname
+ self._cached_offsets = False
+ if self._fname:
+ self._fname = fdt_util.EnsureCompiled(self._fname)
+
+ with open(self._fname) as fd:
+ self._fdt = bytearray(fd.read())
+ self._fdt_obj = libfdt.Fdt(self._fdt)
def Scan(self, root='/'):
"""Scan a device tree, building up a tree of Node objects
"""Flush device tree changes back to the file
If the device tree has changed in memory, write it back to the file.
- Subclasses can implement this if needed.
"""
- pass
+ with open(self._fname, 'wb') as fd:
+ fd.write(self._fdt)
def Pack(self):
"""Pack the device tree down to its minimum size
When nodes and properties shrink or are deleted, wasted space can
- build up in the device tree binary. Subclasses can implement this
- to remove that spare space.
+ build up in the device tree binary.
+ """
+ CheckErr(libfdt.fdt_pack(self._fdt), 'pack')
+ fdt_len = libfdt.fdt_totalsize(self._fdt)
+ del self._fdt[fdt_len:]
+
+ def GetFdt(self):
+ """Get the contents of the FDT
+
+ Returns:
+ The FDT contents as a string of bytes
+ """
+ return self._fdt
+
+ def CheckErr(errnum, msg):
+ if errnum:
+ raise ValueError('Error %d: %s: %s' %
+ (errnum, libfdt.fdt_strerror(errnum), msg))
+
+
+ def GetProps(self, node):
+ """Get all properties from a node.
+
+ Args:
+ node: Full path to node name to look in.
+
+ Returns:
+ A dictionary containing all the properties, indexed by node name.
+ The entries are Prop objects.
+
+ Raises:
+ ValueError: if the node does not exist.
+ """
+ props_dict = {}
+ poffset = libfdt.fdt_first_property_offset(self._fdt, node._offset)
+ while poffset >= 0:
+ p = self._fdt_obj.get_property_by_offset(poffset)
+ prop = Prop(node, poffset, p.name, p.value)
+ props_dict[prop.name] = prop
+
+ poffset = libfdt.fdt_next_property_offset(self._fdt, poffset)
+ return props_dict
+
+ def Invalidate(self):
+ """Mark our offset cache as invalid"""
+ self._cached_offsets = False
+
+ def CheckCache(self):
+ """Refresh the offset cache if needed"""
+ if self._cached_offsets:
+ return
+ self.Refresh()
+ self._cached_offsets = True
+
+ def Refresh(self):
+ """Refresh the offset cache"""
+ self._root.Refresh(0)
+
+ def GetStructOffset(self, offset):
+ """Get the file offset of a given struct offset
+
+ Args:
+ offset: Offset within the 'struct' region of the device tree
+ Returns:
+ Position of @offset within the device tree binary
"""
- pass
+ return libfdt.fdt_off_dt_struct(self._fdt) + offset
+
+ @classmethod
+ def Node(self, fdt, offset, name, path):
+ """Create a new node
+
+ This is used by Fdt.Scan() to create a new node using the correct
+ class.
+
+ Args:
+ fdt: Fdt object
+ offset: Offset of node
+ name: Node name
+ path: Full path to node
+ """
+ node = Node(fdt, offset, name, path)
+ return node
+++ /dev/null
-#!/usr/bin/python
-#
-# Copyright (C) 2016 Google, Inc
-# Written by Simon Glass <sjg@chromium.org>
-#
-# SPDX-License-Identifier: GPL-2.0+
-#
-
-import struct
-import sys
-
-import fdt
-from fdt import Fdt, NodeBase, PropBase
-import fdt_util
-import libfdt
-
-
-# This deals with a device tree, presenting it as a list of Node and Prop
-# objects, representing nodes and properties, respectively.
-#
-# This implementation uses a libfdt Python library to access the device tree,
-# so it is fairly efficient.
-
-def CheckErr(errnum, msg):
- if errnum:
- raise ValueError('Error %d: %s: %s' %
- (errnum, libfdt.fdt_strerror(errnum), msg))
-
-class Prop(PropBase):
- """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, node, offset, name, bytes):
- PropBase.__init__(self, node, offset, name)
- self.bytes = str(bytes)
- if not bytes:
- self.type = fdt.TYPE_BOOL
- self.value = True
- return
- self.type, self.value = self.BytesToValue(bytes)
-
- def GetOffset(self):
- """Get the offset of a property
-
- Returns:
- The offset of the property (struct fdt_property) within the file
- """
- return self._node._fdt.GetStructOffset(self._offset)
-
-class Node(NodeBase):
- """A device tree node
-
- Properties:
- offset: Integer offset in the device tree
- 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, offset, name, path):
- NodeBase.__init__(self, fdt, offset, name, path)
-
- def Offset(self):
- """Returns the offset of a node, after checking the cache
-
- This should be used instead of self._offset directly, to ensure that
- the cache does not contain invalid offsets.
- """
- self._fdt.CheckCache()
- return self._offset
-
- 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.
- """
- self.props = self._fdt.GetProps(self)
-
- offset = libfdt.fdt_first_subnode(self._fdt.GetFdt(), self.Offset())
- while offset >= 0:
- sep = '' if self.path[-1] == '/' else '/'
- name = self._fdt._fdt_obj.get_name(offset)
- path = self.path + sep + name
- node = Node(self._fdt, offset, name, path)
- self.subnodes.append(node)
-
- node.Scan()
- offset = libfdt.fdt_next_subnode(self._fdt.GetFdt(), offset)
-
- def Refresh(self, my_offset):
- """Fix up the _offset for each node, recursively
-
- Note: This does not take account of property offsets - these will not
- be updated.
- """
- if self._offset != my_offset:
- #print '%s: %d -> %d\n' % (self.path, self._offset, my_offset)
- self._offset = my_offset
- offset = libfdt.fdt_first_subnode(self._fdt.GetFdt(), self._offset)
- for subnode in self.subnodes:
- subnode.Refresh(offset)
- offset = libfdt.fdt_next_subnode(self._fdt.GetFdt(), offset)
-
- def DeleteProp(self, prop_name):
- """Delete a property of a node
-
- The property is deleted and the offset cache is invalidated.
-
- Args:
- prop_name: Name of the property to delete
- Raises:
- ValueError if the property does not exist
- """
- CheckErr(libfdt.fdt_delprop(self._fdt.GetFdt(), self.Offset(), prop_name),
- "Node '%s': delete property: '%s'" % (self.path, prop_name))
- del self.props[prop_name]
- self._fdt.Invalidate()
-
-class FdtNormal(Fdt):
- """Provides simple access to a flat device tree blob using libfdt.
-
- Properties:
- _fdt: Device tree contents (bytearray)
- _cached_offsets: True if all the nodes have a valid _offset property,
- False if something has changed to invalidate the offsets
- """
- def __init__(self, fname):
- Fdt.__init__(self, fname)
- self._cached_offsets = False
- if self._fname:
- self._fname = fdt_util.EnsureCompiled(self._fname)
-
- with open(self._fname) as fd:
- self._fdt = bytearray(fd.read())
- self._fdt_obj = libfdt.Fdt(self._fdt)
-
- def GetFdt(self):
- """Get the contents of the FDT
-
- Returns:
- The FDT contents as a string of bytes
- """
- return self._fdt
-
- def Flush(self):
- """Flush device tree changes back to the file"""
- with open(self._fname, 'wb') as fd:
- fd.write(self._fdt)
-
- def Pack(self):
- """Pack the device tree down to its minimum size"""
- CheckErr(libfdt.fdt_pack(self._fdt), 'pack')
- fdt_len = libfdt.fdt_totalsize(self._fdt)
- del self._fdt[fdt_len:]
-
- def GetProps(self, node):
- """Get all properties from a node.
-
- Args:
- node: Full path to node name to look in.
-
- Returns:
- A dictionary containing all the properties, indexed by node name.
- The entries are Prop objects.
-
- Raises:
- ValueError: if the node does not exist.
- """
- props_dict = {}
- poffset = libfdt.fdt_first_property_offset(self._fdt, node._offset)
- while poffset >= 0:
- p = self._fdt_obj.get_property_by_offset(poffset)
- prop = Prop(node, poffset, p.name, p.value)
- props_dict[prop.name] = prop
-
- poffset = libfdt.fdt_next_property_offset(self._fdt, poffset)
- return props_dict
-
- def Invalidate(self):
- """Mark our offset cache as invalid"""
- self._cached_offsets = False
-
- def CheckCache(self):
- """Refresh the offset cache if needed"""
- if self._cached_offsets:
- return
- self.Refresh()
- self._cached_offsets = True
-
- def Refresh(self):
- """Refresh the offset cache"""
- self._root.Refresh(0)
-
- def GetStructOffset(self, offset):
- """Get the file offset of a given struct offset
-
- Args:
- offset: Offset within the 'struct' region of the device tree
- Returns:
- Position of @offset within the device tree binary
- """
- return libfdt.fdt_off_dt_struct(self._fdt) + offset
-
- @classmethod
- def Node(self, fdt, offset, name, path):
- """Create a new node
-
- This is used by Fdt.Scan() to create a new node using the correct
- class.
-
- Args:
- fdt: Fdt object
- offset: Offset of node
- name: Node name
- path: Full path to node
- """
- node = Node(fdt, offset, name, path)
- return node
# SPDX-License-Identifier: GPL-2.0+
#
-# Bring in either the normal fdt library (which relies on libfdt) or the
-# fallback one (which uses fdtget and is slower). Both provide the same
-# interface for this file to use.
-import fdt_normal
+# Bring in the normal fdt library (which relies on libfdt)
+import fdt
def FdtScan(fname):
"""Returns a new Fdt object from the implementation we are using"""
- dtb = fdt_normal.FdtNormal(fname)
+ dtb = fdt.Fdt(fname)
dtb.Scan()
return dtb
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