2 # SPDX-License-Identifier: GPL-2.0+
4 # Copyright (C) 2016 Google, Inc
5 # Written by Simon Glass <sjg@chromium.org>
8 from enum import IntEnum
12 from dtoc import fdt_util
14 from libfdt import QUIET_NOTFOUND
15 from patman import tools
17 # This deals with a device tree, presenting it as an assortment of Node and
18 # Prop objects, representing nodes and properties, respectively. This file
19 # contains the base classes and defines the high-level API. You can use
20 # FdtScan() as a convenience function to create and scan an Fdt.
22 # This implementation uses a libfdt Python library to access the device tree,
23 # so it is fairly efficient.
25 # A list of types we support
27 (BYTE, INT, STRING, BOOL, INT64) = range(5)
29 def is_wider_than(self, other):
30 """Check if another type is 'wider' than this one
32 A wider type is one that holds more information than an earlier one,
33 similar to the concept of type-widening in C.
35 This uses a simple arithmetic comparison, since type values are in order
36 from narrowest (BYTE) to widest (INT64).
39 other: Other type to compare against
42 True if the other type is wider
44 return self.value > other.value
46 def CheckErr(errnum, msg):
48 raise ValueError('Error %d: %s: %s' %
49 (errnum, libfdt.fdt_strerror(errnum), msg))
52 def BytesToValue(data):
53 """Converts a string of bytes into a type and value
56 A bytes value (which on Python 2 is an alias for str)
61 Data, either a single element or a list of elements. Each element
63 Type.STRING: str/bytes value from the property
64 Type.INT: a byte-swapped integer stored as a 4-byte str/bytes
65 Type.BYTE: a byte stored as a single-byte str/bytes
69 strings = data.split(b'\0')
71 count = len(strings) - 1
72 if count > 0 and not len(strings[-1]):
73 for string in strings[:-1]:
78 if ch < 32 or ch > 127:
85 return Type.STRING, strings[0].decode()
87 return Type.STRING, [s.decode() for s in strings[:-1]]
90 return Type.BYTE, chr(data[0])
92 return Type.BYTE, [chr(ch) for ch in list(data)]
94 for i in range(0, size, 4):
95 val.append(data[i:i + 4])
97 return Type.INT, val[0]
103 """A device tree property
106 name: Property name (as per the device tree)
107 value: Property value as a string of bytes, or a list of strings of
111 def __init__(self, node, offset, name, data):
113 self._offset = offset
116 self.bytes = bytes(data)
119 self.type = Type.BOOL
122 self.type, self.value = BytesToValue(bytes(data))
124 def RefreshOffset(self, poffset):
125 self._offset = poffset
127 def Widen(self, newprop):
128 """Figure out which property type is more general
130 Given a current property and a new property, this function returns the
131 one that is less specific as to type. The less specific property will
132 be ble to represent the data in the more specific property. This is
133 used for things like:
144 He we want to use an int array for 'value'. The first property
145 suggests that a single int is enough, but the second one shows that
146 it is not. Calling this function with these two propertes would
147 update the current property to be like the second, since it is less
150 if self.type.is_wider_than(newprop.type):
151 if self.type == Type.INT and newprop.type == Type.BYTE:
152 if type(self.value) == list:
154 for val in self.value:
155 new_value += [chr(by) for by in val]
157 new_value = [chr(by) for by in self.value]
158 self.value = new_value
159 self.type = newprop.type
161 if type(newprop.value) == list and type(self.value) != list:
162 self.value = [self.value]
164 if type(self.value) == list and len(newprop.value) > len(self.value):
165 val = self.GetEmpty(self.type)
166 while len(self.value) < len(newprop.value):
167 self.value.append(val)
170 def GetEmpty(self, type):
171 """Get an empty / zero value of the given type
174 A single value of the given type
176 if type == Type.BYTE:
178 elif type == Type.INT:
179 return struct.pack('>I', 0);
180 elif type == Type.STRING:
186 """Get the offset of a property
189 The offset of the property (struct fdt_property) within the file
191 self._node._fdt.CheckCache()
192 return self._node._fdt.GetStructOffset(self._offset)
194 def SetInt(self, val):
195 """Set the integer value of the property
197 The device tree is marked dirty so that the value will be written to
198 the block on the next sync.
201 val: Integer value (32-bit, single cell)
203 self.bytes = struct.pack('>I', val);
204 self.value = self.bytes
208 def SetData(self, bytes):
209 """Set the value of a property as bytes
212 bytes: New property value to set
215 self.type, self.value = BytesToValue(bytes)
218 def Sync(self, auto_resize=False):
219 """Sync property changes back to the device tree
221 This updates the device tree blob with any changes to this property
225 auto_resize: Resize the device tree automatically if it does not
226 have enough space for the update
229 FdtException if auto_resize is False and there is not enough space
231 if self._offset is None or self.dirty:
233 fdt_obj = node._fdt._fdt_obj
235 while fdt_obj.setprop(node.Offset(), self.name, self.bytes,
236 (libfdt.NOSPACE,)) == -libfdt.NOSPACE:
237 fdt_obj.resize(fdt_obj.totalsize() + 1024 +
239 fdt_obj.setprop(node.Offset(), self.name, self.bytes)
241 fdt_obj.setprop(node.Offset(), self.name, self.bytes)
245 """A device tree node
248 offset: Integer offset in the device tree
249 name: Device tree node tname
250 path: Full path to node, along with the node name itself
251 _fdt: Device tree object
252 subnodes: A list of subnodes for this node, each a Node object
253 props: A dict of properties for this node, each a Prop object.
254 Keyed by property name
256 def __init__(self, fdt, parent, offset, name, path):
259 self._offset = offset
266 """Get the Fdt object for this node
273 def FindNode(self, name):
274 """Find a node given its name
277 name: Node name to look for
279 Node object if found, else None
281 for subnode in self.subnodes:
282 if subnode.name == name:
287 """Returns the offset of a node, after checking the cache
289 This should be used instead of self._offset directly, to ensure that
290 the cache does not contain invalid offsets.
292 self._fdt.CheckCache()
296 """Scan a node's properties and subnodes
298 This fills in the props and subnodes properties, recursively
299 searching into subnodes so that the entire tree is built.
301 fdt_obj = self._fdt._fdt_obj
302 self.props = self._fdt.GetProps(self)
303 phandle = fdt_obj.get_phandle(self.Offset())
305 self._fdt.phandle_to_node[phandle] = self
307 offset = fdt_obj.first_subnode(self.Offset(), QUIET_NOTFOUND)
309 sep = '' if self.path[-1] == '/' else '/'
310 name = fdt_obj.get_name(offset)
311 path = self.path + sep + name
312 node = Node(self._fdt, self, offset, name, path)
313 self.subnodes.append(node)
316 offset = fdt_obj.next_subnode(offset, QUIET_NOTFOUND)
318 def Refresh(self, my_offset):
319 """Fix up the _offset for each node, recursively
321 Note: This does not take account of property offsets - these will not
324 fdt_obj = self._fdt._fdt_obj
325 if self._offset != my_offset:
326 self._offset = my_offset
327 offset = fdt_obj.first_subnode(self._offset, QUIET_NOTFOUND)
328 for subnode in self.subnodes:
329 if subnode.name != fdt_obj.get_name(offset):
330 raise ValueError('Internal error, node name mismatch %s != %s' %
331 (subnode.name, fdt_obj.get_name(offset)))
332 subnode.Refresh(offset)
333 offset = fdt_obj.next_subnode(offset, QUIET_NOTFOUND)
334 if offset != -libfdt.FDT_ERR_NOTFOUND:
335 raise ValueError('Internal error, offset == %d' % offset)
337 poffset = fdt_obj.first_property_offset(self._offset, QUIET_NOTFOUND)
339 p = fdt_obj.get_property_by_offset(poffset)
340 prop = self.props.get(p.name)
342 raise ValueError("Internal error, property '%s' missing, "
343 'offset %d' % (p.name, poffset))
344 prop.RefreshOffset(poffset)
345 poffset = fdt_obj.next_property_offset(poffset, QUIET_NOTFOUND)
347 def DeleteProp(self, prop_name):
348 """Delete a property of a node
350 The property is deleted and the offset cache is invalidated.
353 prop_name: Name of the property to delete
355 ValueError if the property does not exist
357 CheckErr(self._fdt._fdt_obj.delprop(self.Offset(), prop_name),
358 "Node '%s': delete property: '%s'" % (self.path, prop_name))
359 del self.props[prop_name]
360 self._fdt.Invalidate()
362 def AddZeroProp(self, prop_name):
363 """Add a new property to the device tree with an integer value of 0.
366 prop_name: Name of property
368 self.props[prop_name] = Prop(self, None, prop_name,
369 tools.GetBytes(0, 4))
371 def AddEmptyProp(self, prop_name, len):
372 """Add a property with a fixed data size, for filling in later
374 The device tree is marked dirty so that the value will be written to
375 the blob on the next sync.
378 prop_name: Name of property
379 len: Length of data in property
381 value = tools.GetBytes(0, len)
382 self.props[prop_name] = Prop(self, None, prop_name, value)
384 def _CheckProp(self, prop_name):
385 """Check if a property is present
388 prop_name: Name of property
394 ValueError if the property is missing
396 if prop_name not in self.props:
397 raise ValueError("Fdt '%s', node '%s': Missing property '%s'" %
398 (self._fdt._fname, self.path, prop_name))
401 def SetInt(self, prop_name, val):
402 """Update an integer property int the device tree.
404 This is not allowed to change the size of the FDT.
406 The device tree is marked dirty so that the value will be written to
407 the blob on the next sync.
410 prop_name: Name of property
413 self._CheckProp(prop_name).props[prop_name].SetInt(val)
415 def SetData(self, prop_name, val):
416 """Set the data value of a property
418 The device tree is marked dirty so that the value will be written to
419 the blob on the next sync.
422 prop_name: Name of property to set
423 val: Data value to set
425 self._CheckProp(prop_name).props[prop_name].SetData(val)
427 def SetString(self, prop_name, val):
428 """Set the string value of a property
430 The device tree is marked dirty so that the value will be written to
431 the blob on the next sync.
434 prop_name: Name of property to set
435 val: String value to set (will be \0-terminated in DT)
438 val = val.encode('utf-8')
439 self._CheckProp(prop_name).props[prop_name].SetData(val + b'\0')
441 def AddData(self, prop_name, val):
442 """Add a new property to a node
444 The device tree is marked dirty so that the value will be written to
445 the blob on the next sync.
448 prop_name: Name of property to add
449 val: Bytes value of property
451 self.props[prop_name] = Prop(self, None, prop_name, val)
453 def AddString(self, prop_name, val):
454 """Add a new string property to a node
456 The device tree is marked dirty so that the value will be written to
457 the blob on the next sync.
460 prop_name: Name of property to add
461 val: String value of property
463 if sys.version_info[0] >= 3: # pragma: no cover
464 val = bytes(val, 'utf-8')
465 self.AddData(prop_name, val + b'\0')
467 def AddSubnode(self, name):
468 """Add a new subnode to the node
471 name: name of node to add
474 New subnode that was created
476 path = self.path + '/' + name
477 subnode = Node(self._fdt, self, None, name, path)
478 self.subnodes.append(subnode)
481 def Sync(self, auto_resize=False):
482 """Sync node changes back to the device tree
484 This updates the device tree blob with any changes to this node and its
485 subnodes since the last sync.
488 auto_resize: Resize the device tree automatically if it does not
489 have enough space for the update
492 FdtException if auto_resize is False and there is not enough space
494 if self._offset is None:
495 # The subnode doesn't exist yet, so add it
496 fdt_obj = self._fdt._fdt_obj
499 offset = fdt_obj.add_subnode(self.parent._offset, self.name,
501 if offset != -libfdt.NOSPACE:
503 fdt_obj.resize(fdt_obj.totalsize() + 1024)
505 offset = fdt_obj.add_subnode(self.parent._offset, self.name)
506 self._offset = offset
508 # Sync subnodes in reverse so that we don't disturb node offsets for
509 # nodes that are earlier in the DT. This avoids an O(n^2) rescan of
511 for node in reversed(self.subnodes):
512 node.Sync(auto_resize)
514 # Sync properties now, whose offsets should not have been disturbed.
515 # We do this after subnodes, since this disturbs the offsets of these
516 # properties. Note that new properties will have an offset of None here,
517 # which Python 3 cannot sort against int. So use a large value instead
518 # to ensure that the new properties are added first.
519 prop_list = sorted(self.props.values(),
520 key=lambda prop: prop._offset or 1 << 31,
522 for prop in prop_list:
523 prop.Sync(auto_resize)
527 """Provides simple access to a flat device tree blob using libfdts.
530 fname: Filename of fdt
531 _root: Root of device tree (a Node object)
532 name: Helpful name for this Fdt for the user (useful when creating the
533 DT from data rather than a file)
535 def __init__(self, fname):
537 self._cached_offsets = False
538 self.phandle_to_node = {}
541 self.name = self._fname
542 self._fname = fdt_util.EnsureCompiled(self._fname)
544 with open(self._fname, 'rb') as fd:
545 self._fdt_obj = libfdt.Fdt(fd.read())
548 def FromData(data, name=''):
549 """Create a new Fdt object from the given data
552 data: Device-tree data blob
553 name: Helpful name for this Fdt for the user
556 Fdt object containing the data
559 fdt._fdt_obj = libfdt.Fdt(bytes(data))
563 def LookupPhandle(self, phandle):
567 phandle: Phandle to look up (int)
570 Node object the phandle points to
572 return self.phandle_to_node.get(phandle)
574 def Scan(self, root='/'):
575 """Scan a device tree, building up a tree of Node objects
577 This fills in the self._root property
582 TODO(sjg@chromium.org): Implement the 'root' parameter
584 self._cached_offsets = True
585 self._root = self.Node(self, None, 0, '/', '/')
589 """Get the root Node of the device tree
596 def GetNode(self, path):
597 """Look up a node from its path
600 path: Path to look up, e.g. '/microcode/update@0'
602 Node object, or None if not found
605 parts = path.split('/')
608 if len(parts) == 2 and parts[1] == '':
610 for part in parts[1:]:
611 node = node.FindNode(part)
617 """Flush device tree changes back to the file
619 If the device tree has changed in memory, write it back to the file.
621 with open(self._fname, 'wb') as fd:
622 fd.write(self._fdt_obj.as_bytearray())
624 def Sync(self, auto_resize=False):
625 """Make sure any DT changes are written to the blob
628 auto_resize: Resize the device tree automatically if it does not
629 have enough space for the update
632 FdtException if auto_resize is False and there is not enough space
634 self._root.Sync(auto_resize)
638 """Pack the device tree down to its minimum size
640 When nodes and properties shrink or are deleted, wasted space can
641 build up in the device tree binary.
643 CheckErr(self._fdt_obj.pack(), 'pack')
646 def GetContents(self):
647 """Get the contents of the FDT
650 The FDT contents as a string of bytes
652 return bytes(self._fdt_obj.as_bytearray())
655 """Get the contents of the FDT
658 The FDT contents as a libfdt.Fdt object
662 def GetProps(self, node):
663 """Get all properties from a node.
666 node: Full path to node name to look in.
669 A dictionary containing all the properties, indexed by node name.
670 The entries are Prop objects.
673 ValueError: if the node does not exist.
676 poffset = self._fdt_obj.first_property_offset(node._offset,
679 p = self._fdt_obj.get_property_by_offset(poffset)
680 prop = Prop(node, poffset, p.name, p)
681 props_dict[prop.name] = prop
683 poffset = self._fdt_obj.next_property_offset(poffset,
687 def Invalidate(self):
688 """Mark our offset cache as invalid"""
689 self._cached_offsets = False
691 def CheckCache(self):
692 """Refresh the offset cache if needed"""
693 if self._cached_offsets:
696 self._cached_offsets = True
699 """Refresh the offset cache"""
700 self._root.Refresh(0)
702 def GetStructOffset(self, offset):
703 """Get the file offset of a given struct offset
706 offset: Offset within the 'struct' region of the device tree
708 Position of @offset within the device tree binary
710 return self._fdt_obj.off_dt_struct() + offset
713 def Node(self, fdt, parent, offset, name, path):
716 This is used by Fdt.Scan() to create a new node using the correct
721 parent: Parent node, or None if this is the root node
722 offset: Offset of node
724 path: Full path to node
726 node = Node(fdt, parent, offset, name, path)
729 def GetFilename(self):
730 """Get the filename of the device tree
738 """Returns a new Fdt object"""