diff options
Diffstat (limited to 'tools/dtoc/fdt_normal.py')
| -rw-r--r-- | tools/dtoc/fdt_normal.py | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/tools/dtoc/fdt_normal.py b/tools/dtoc/fdt_normal.py new file mode 100644 index 0000000..aae258e --- /dev/null +++ b/tools/dtoc/fdt_normal.py @@ -0,0 +1,228 @@ +#!/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 = 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, self.path) + + offset = libfdt.fdt_first_subnode(self._fdt.GetFdt(), self.Offset()) + while offset >= 0: + sep = '' if self.path[-1] == '/' else '/' + name = libfdt.Name(self._fdt.GetFdt(), 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()) + + 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, path): + """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. + """ + offset = libfdt.fdt_path_offset(self._fdt, path) + if offset < 0: + libfdt.Raise(offset) + props_dict = {} + poffset = libfdt.fdt_first_property_offset(self._fdt, offset) + while poffset >= 0: + dprop, plen = libfdt.fdt_get_property_by_offset(self._fdt, poffset) + prop = Prop(node, poffset, libfdt.String(self._fdt, dprop.nameoff), + libfdt.Data(dprop)) + 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 |