#!/usr/bin/python
+# SPDX-License-Identifier: GPL-2.0+
#
# Copyright (C) 2016 Google, Inc
# Written by Simon Glass <sjg@chromium.org>
#
-# SPDX-License-Identifier: GPL-2.0+
-#
import struct
import sys
import fdt_util
+import libfdt
+from libfdt import QUIET_NOTFOUND
# 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. You can use
+# FdtScan() as a convenience function to create and scan an Fdt.
+
+# 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)
+(TYPE_BYTE, TYPE_INT, TYPE_STRING, TYPE_BOOL, TYPE_INT64) = range(5)
def CheckErr(errnum, msg):
if errnum:
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
else:
return TYPE_INT, val
+ @classmethod
def GetEmpty(self, type):
"""Get an empty / zero value of the given type
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:
props: A dict of properties for this node, each a Prop object.
Keyed by property name
"""
- def __init__(self, fdt, offset, name, path):
+ def __init__(self, fdt, parent, offset, name, path):
self._fdt = fdt
+ self.parent = parent
self._offset = offset
self.name = name
self.path = path
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 should be implemented by subclasses
+ This fills in the props and subnodes properties, recursively
+ searching into subnodes so that the entire tree is built.
+ """
+ fdt_obj = self._fdt._fdt_obj
+ self.props = self._fdt.GetProps(self)
+ phandle = fdt_obj.get_phandle(self.Offset())
+ if phandle:
+ self._fdt.phandle_to_node[phandle] = self
+
+ offset = fdt_obj.first_subnode(self.Offset(), QUIET_NOTFOUND)
+ while offset >= 0:
+ sep = '' if self.path[-1] == '/' else '/'
+ name = fdt_obj.get_name(offset)
+ path = self.path + sep + name
+ node = Node(self._fdt, self, offset, name, path)
+ self.subnodes.append(node)
+
+ node.Scan()
+ offset = fdt_obj.next_subnode(offset, QUIET_NOTFOUND)
+
+ 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()
+ fdt_obj = self._fdt._fdt_obj
+ if self._offset != my_offset:
+ self._offset = my_offset
+ offset = fdt_obj.first_subnode(self._offset, QUIET_NOTFOUND)
+ for subnode in self.subnodes:
+ subnode.Refresh(offset)
+ offset = fdt_obj.next_subnode(offset, QUIET_NOTFOUND)
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(self._fdt._fdt_obj.delprop(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
+ self.phandle_to_node = {}
+ if self._fname:
+ self._fname = fdt_util.EnsureCompiled(self._fname)
+
+ with open(self._fname) as fd:
+ self._fdt_obj = libfdt.Fdt(fd.read())
def Scan(self, root='/'):
"""Scan a device tree, building up a tree of Node objects
TODO(sjg@chromium.org): Implement the 'root' parameter
"""
- self._root = self.Node(self, 0, '/', '/')
+ self._root = self.Node(self, None, 0, '/', '/')
self._root.Scan()
def GetRoot(self):
"""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_obj.as_bytearray())
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.
"""
- pass
+ CheckErr(self._fdt_obj.pack(), 'pack')
+ self.Invalidate()
+
+ def GetContents(self):
+ """Get the contents of the FDT
+
+ Returns:
+ The FDT contents as a string of bytes
+ """
+ return self._fdt_obj.as_bytearray()
+
+ def GetFdtObj(self):
+ """Get the contents of the FDT
+
+ Returns:
+ The FDT contents as a libfdt.Fdt object
+ """
+ return self._fdt_obj
+
+ def CheckErr(self, 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 = self._fdt_obj.first_property_offset(node._offset,
+ QUIET_NOTFOUND)
+ while poffset >= 0:
+ p = self._fdt_obj.get_property_by_offset(poffset)
+ prop = Prop(node, poffset, p.name, p)
+ props_dict[prop.name] = prop
+
+ poffset = self._fdt_obj.next_property_offset(poffset,
+ QUIET_NOTFOUND)
+ 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 self._fdt_obj.off_dt_struct() + offset
+
+ @classmethod
+ def Node(self, fdt, parent, 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
+ parent: Parent node, or None if this is the root node
+ offset: Offset of node
+ name: Node name
+ path: Full path to node
+ """
+ node = Node(fdt, parent, offset, name, path)
+ return node
+
+def FdtScan(fname):
+ """Returns a new Fdt object from the implementation we are using"""
+ dtb = Fdt(fname)
+ dtb.Scan()
+ return dtb
projects / u-boot / blobdiff