Since we only have one Fdt implementation now we don't need to have a base class. Merge the implementation and the base class together. Signed-off-by: Simon Glass <sjg@chromium.org>master
Simon Glass
7 years ago
parent
515d3f0801
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7b75b4482d
@ -1,226 +0,0 @@ |
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#!/usr/bin/python |
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# |
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# Copyright (C) 2016 Google, Inc |
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# Written by Simon Glass <sjg@chromium.org> |
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# |
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# SPDX-License-Identifier: GPL-2.0+ |
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# |
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|
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import struct |
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import sys |
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|
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import fdt |
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from fdt import Fdt, NodeBase, PropBase |
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import fdt_util |
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import libfdt |
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# This deals with a device tree, presenting it as a list of Node and Prop |
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# objects, representing nodes and properties, respectively. |
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# |
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# This implementation uses a libfdt Python library to access the device tree, |
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# so it is fairly efficient. |
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|
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def CheckErr(errnum, msg): |
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if errnum: |
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raise ValueError('Error %d: %s: %s' % |
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(errnum, libfdt.fdt_strerror(errnum), msg)) |
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|
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class Prop(PropBase): |
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"""A device tree property |
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Properties: |
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name: Property name (as per the device tree) |
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value: Property value as a string of bytes, or a list of strings of |
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bytes |
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type: Value type |
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""" |
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def __init__(self, node, offset, name, bytes): |
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PropBase.__init__(self, node, offset, name) |
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self.bytes = str(bytes) |
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if not bytes: |
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self.type = fdt.TYPE_BOOL |
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self.value = True |
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return |
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self.type, self.value = self.BytesToValue(bytes) |
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|
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def GetOffset(self): |
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"""Get the offset of a property |
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Returns: |
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The offset of the property (struct fdt_property) within the file |
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""" |
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return self._node._fdt.GetStructOffset(self._offset) |
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|
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class Node(NodeBase): |
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"""A device tree node |
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Properties: |
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offset: Integer offset in the device tree |
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name: Device tree node tname |
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path: Full path to node, along with the node name itself |
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_fdt: Device tree object |
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subnodes: A list of subnodes for this node, each a Node object |
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props: A dict of properties for this node, each a Prop object. |
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Keyed by property name |
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""" |
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def __init__(self, fdt, offset, name, path): |
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NodeBase.__init__(self, fdt, offset, name, path) |
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def Offset(self): |
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"""Returns the offset of a node, after checking the cache |
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This should be used instead of self._offset directly, to ensure that |
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the cache does not contain invalid offsets. |
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""" |
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self._fdt.CheckCache() |
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return self._offset |
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def Scan(self): |
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"""Scan a node's properties and subnodes |
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This fills in the props and subnodes properties, recursively |
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searching into subnodes so that the entire tree is built. |
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""" |
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self.props = self._fdt.GetProps(self) |
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offset = libfdt.fdt_first_subnode(self._fdt.GetFdt(), self.Offset()) |
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while offset >= 0: |
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sep = '' if self.path[-1] == '/' else '/' |
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name = self._fdt._fdt_obj.get_name(offset) |
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path = self.path + sep + name |
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node = Node(self._fdt, offset, name, path) |
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self.subnodes.append(node) |
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node.Scan() |
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offset = libfdt.fdt_next_subnode(self._fdt.GetFdt(), offset) |
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def Refresh(self, my_offset): |
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"""Fix up the _offset for each node, recursively |
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Note: This does not take account of property offsets - these will not |
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be updated. |
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""" |
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if self._offset != my_offset: |
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#print '%s: %d -> %d\n' % (self.path, self._offset, my_offset) |
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self._offset = my_offset |
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offset = libfdt.fdt_first_subnode(self._fdt.GetFdt(), self._offset) |
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for subnode in self.subnodes: |
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subnode.Refresh(offset) |
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offset = libfdt.fdt_next_subnode(self._fdt.GetFdt(), offset) |
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def DeleteProp(self, prop_name): |
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"""Delete a property of a node |
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The property is deleted and the offset cache is invalidated. |
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Args: |
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prop_name: Name of the property to delete |
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Raises: |
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ValueError if the property does not exist |
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""" |
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CheckErr(libfdt.fdt_delprop(self._fdt.GetFdt(), self.Offset(), prop_name), |
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"Node '%s': delete property: '%s'" % (self.path, prop_name)) |
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del self.props[prop_name] |
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self._fdt.Invalidate() |
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class FdtNormal(Fdt): |
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"""Provides simple access to a flat device tree blob using libfdt. |
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Properties: |
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_fdt: Device tree contents (bytearray) |
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_cached_offsets: True if all the nodes have a valid _offset property, |
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False if something has changed to invalidate the offsets |
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""" |
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def __init__(self, fname): |
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Fdt.__init__(self, fname) |
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self._cached_offsets = False |
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if self._fname: |
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self._fname = fdt_util.EnsureCompiled(self._fname) |
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with open(self._fname) as fd: |
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self._fdt = bytearray(fd.read()) |
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self._fdt_obj = libfdt.Fdt(self._fdt) |
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def GetFdt(self): |
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"""Get the contents of the FDT |
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Returns: |
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The FDT contents as a string of bytes |
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""" |
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return self._fdt |
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def Flush(self): |
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"""Flush device tree changes back to the file""" |
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with open(self._fname, 'wb') as fd: |
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fd.write(self._fdt) |
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def Pack(self): |
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"""Pack the device tree down to its minimum size""" |
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CheckErr(libfdt.fdt_pack(self._fdt), 'pack') |
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fdt_len = libfdt.fdt_totalsize(self._fdt) |
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del self._fdt[fdt_len:] |
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def GetProps(self, node): |
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"""Get all properties from a node. |
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Args: |
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node: Full path to node name to look in. |
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Returns: |
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A dictionary containing all the properties, indexed by node name. |
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The entries are Prop objects. |
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Raises: |
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ValueError: if the node does not exist. |
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""" |
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props_dict = {} |
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poffset = libfdt.fdt_first_property_offset(self._fdt, node._offset) |
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while poffset >= 0: |
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p = self._fdt_obj.get_property_by_offset(poffset) |
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prop = Prop(node, poffset, p.name, p.value) |
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props_dict[prop.name] = prop |
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poffset = libfdt.fdt_next_property_offset(self._fdt, poffset) |
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return props_dict |
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def Invalidate(self): |
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"""Mark our offset cache as invalid""" |
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self._cached_offsets = False |
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def CheckCache(self): |
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"""Refresh the offset cache if needed""" |
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if self._cached_offsets: |
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return |
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self.Refresh() |
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self._cached_offsets = True |
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def Refresh(self): |
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"""Refresh the offset cache""" |
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self._root.Refresh(0) |
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def GetStructOffset(self, offset): |
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"""Get the file offset of a given struct offset |
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Args: |
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offset: Offset within the 'struct' region of the device tree |
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Returns: |
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Position of @offset within the device tree binary |
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""" |
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return libfdt.fdt_off_dt_struct(self._fdt) + offset |
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@classmethod |
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def Node(self, fdt, offset, name, path): |
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"""Create a new node |
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This is used by Fdt.Scan() to create a new node using the correct |
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class. |
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Args: |
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fdt: Fdt object |
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offset: Offset of node |
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name: Node name |
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path: Full path to node |
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""" |
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node = Node(fdt, offset, name, path) |
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return node |
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