diff options
Diffstat (limited to 'tools/dtoc/fdt.py')
| -rw-r--r-- | tools/dtoc/fdt.py | 176 |
1 files changed, 154 insertions, 22 deletions
diff --git a/tools/dtoc/fdt.py b/tools/dtoc/fdt.py index dedd3d75010..bff31d1c921 100644 --- a/tools/dtoc/fdt.py +++ b/tools/dtoc/fdt.py @@ -10,12 +10,15 @@ import struct 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) @@ -25,7 +28,7 @@ def CheckErr(errnum, msg): raise ValueError('Error %d: %s: %s' % (errnum, libfdt.fdt_strerror(errnum), msg)) -class PropBase: +class Prop: """A device tree property Properties: @@ -34,11 +37,17 @@ class PropBase: 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 @@ -148,15 +157,12 @@ class PropBase: 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: @@ -189,25 +195,65 @@ class NodeBase: 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 @@ -215,6 +261,13 @@ class 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 @@ -256,15 +309,94 @@ class Fdt: """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 |