--- /dev/null
+#!/usr/bin/python
+#
+# Copyright (C) 2016 Google, Inc
+# Written by Simon Glass <sjg@chromium.org>
+#
+# SPDX-License-Identifier: GPL-2.0+
+#
+
+import command
+import fdt_util
+import sys
+
+# This deals with a device tree, presenting it as a list of Node and Prop
+# objects, representing nodes and properties, respectively.
+#
+# This implementation uses the fdtget tool to access the device tree, so it
+# is not very efficient for larger trees. The tool is called once for each
+# node and property in the tree.
+
+class Prop:
+ """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, name, byte_list_str):
+ self.name = name
+ self.value = None
+ if not byte_list_str.strip():
+ self.type = fdt_util.TYPE_BOOL
+ return
+ bytes = [chr(int(byte, 16)) for byte in byte_list_str.strip().split(' ')]
+ self.type, self.value = fdt_util.BytesToValue(''.join(bytes))
+
+ def GetPhandle(self):
+ """Get a (single) phandle value from a property
+
+ Gets the phandle valuie from a property and returns it as an integer
+ """
+ return fdt_util.fdt32_to_cpu(self.value[:4])
+
+ def Widen(self, newprop):
+ """Figure out which property type is more general
+
+ Given a current property and a new property, this function returns the
+ one that is less specific as to type. The less specific property will
+ be ble to represent the data in the more specific property. This is
+ used for things like:
+
+ node1 {
+ compatible = "fred";
+ value = <1>;
+ };
+ node1 {
+ compatible = "fred";
+ value = <1 2>;
+ };
+
+ He we want to use an int array for 'value'. The first property
+ suggests that a single int is enough, but the second one shows that
+ it is not. Calling this function with these two propertes would
+ update the current property to be like the second, since it is less
+ specific.
+ """
+ if newprop.type < self.type:
+ self.type = newprop.type
+
+ if type(newprop.value) == list and type(self.value) != list:
+ self.value = newprop.value
+
+class Node:
+ """A device tree node
+
+ Properties:
+ 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, name, path):
+ self.name = name
+ self.path = path
+ self._fdt = fdt
+ self.subnodes = []
+ self.props = {}
+
+ 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.
+ """
+ for name, byte_list_str in self._fdt.GetProps(self.path).iteritems():
+ prop = Prop(name, byte_list_str)
+ self.props[name] = prop
+
+ for name in self._fdt.GetSubNodes(self.path):
+ sep = '' if self.path[-1] == '/' else '/'
+ path = self.path + sep + name
+ node = Node(self._fdt, name, path)
+ self.subnodes.append(node)
+
+ node.Scan()
+
+
+class Fdt:
+ """Provides simple access to a flat device tree blob.
+
+ Properties:
+ fname: Filename of fdt
+ _root: Root of device tree (a Node object)
+ """
+
+ def __init__(self, fname):
+ self.fname = fname
+
+ def Scan(self):
+ """Scan a device tree, building up a tree of Node objects
+
+ This fills in the self._root property
+ """
+ self._root = Node(self, '/', '/')
+ self._root.Scan()
+
+ def GetRoot(self):
+ """Get the root Node of the device tree
+
+ Returns:
+ The root Node object
+ """
+ return self._root
+
+ def GetSubNodes(self, node):
+ """Returns a list of sub-nodes of a given node
+
+ Args:
+ node: Node name to return children from
+
+ Returns:
+ List of children in the node (each a string node name)
+
+ Raises:
+ CmdError: if the node does not exist.
+ """
+ out = command.Output('fdtget', self.fname, '-l', node)
+ return out.strip().splitlines()
+
+ def GetProps(self, node, convert_dashes=False):
+ """Get all properties from a node
+
+ Args:
+ node: full path to node name to look in
+ convert_dashes: True to convert - to _ in node names
+
+ Returns:
+ A dictionary containing all the properties, indexed by node name.
+ The entries are simply strings - no decoding of lists or numbers
+ is done.
+
+ Raises:
+ CmdError: if the node does not exist.
+ """
+ out = command.Output('fdtget', self.fname, node, '-p')
+ props = out.strip().splitlines()
+ props_dict = {}
+ for prop in props:
+ name = prop
+ if convert_dashes:
+ prop = re.sub('-', '_', prop)
+ props_dict[prop] = self.GetProp(node, name)
+ return props_dict
+
+ def GetProp(self, node, prop, default=None, typespec=None):
+ """Get a property from a device tree.
+
+ This looks up the given node and property, and returns the value as a
+ string,
+
+ If the node or property does not exist, this will return the default
+ value.
+
+ Args:
+ node: Full path to node to look up.
+ prop: Property name to look up.
+ default: Default value to return if nothing is present in the fdt,
+ or None to raise in this case. This will be converted to a
+ string.
+ typespec: Type character to use (None for default, 's' for string)
+
+ Returns:
+ string containing the property value.
+
+ Raises:
+ CmdError: if the property does not exist and no default is provided.
+ """
+ args = [self.fname, node, prop, '-t', 'bx']
+ if default is not None:
+ args += ['-d', str(default)]
+ if typespec is not None:
+ args += ['-t%s' % typespec]
+ out = command.Output('fdtget', *args)
+ return out.strip()
--- /dev/null
+#!/usr/bin/python
+#
+# Copyright (C) 2016 Google, Inc
+# Written by Simon Glass <sjg@chromium.org>
+#
+# SPDX-License-Identifier: GPL-2.0+
+#
+
+import struct
+
+# A list of types we support
+(TYPE_BYTE, TYPE_INT, TYPE_STRING, TYPE_BOOL) = range(4)
+
+def BytesToValue(bytes):
+ """Converts a string of bytes into a type and value
+
+ Args:
+ A string containing bytes
+
+ Return:
+ A tuple:
+ Type of data
+ Data, either a single element or a list of elements. Each element
+ is one of:
+ TYPE_STRING: string value from the property
+ TYPE_INT: a byte-swapped integer stored as a 4-byte string
+ TYPE_BYTE: a byte stored as a single-byte string
+ """
+ size = len(bytes)
+ strings = bytes.split('\0')
+ is_string = True
+ count = len(strings) - 1
+ if count > 0 and not strings[-1]:
+ for string in strings[:-1]:
+ if not string:
+ is_string = False
+ break
+ for ch in string:
+ if ch < ' ' or ch > '~':
+ is_string = False
+ break
+ else:
+ is_string = False
+ if is_string:
+ if count == 1:
+ return TYPE_STRING, strings[0]
+ else:
+ return TYPE_STRING, strings[:-1]
+ if size % 4:
+ if size == 1:
+ return TYPE_BYTE, bytes[0]
+ else:
+ return TYPE_BYTE, list(bytes)
+ val = []
+ for i in range(0, size, 4):
+ val.append(bytes[i:i + 4])
+ if size == 4:
+ return TYPE_INT, val[0]
+ else:
+ return TYPE_INT, val
+
+def GetEmpty(type):
+ """Get an empty / zero value of the given type
+
+ Returns:
+ A single value of the given type
+ """
+ if type == TYPE_BYTE:
+ return chr(0)
+ elif type == TYPE_INT:
+ return struct.pack('<I', 0);
+ elif type == TYPE_STRING:
+ return ''
+ else:
+ return True
+
+def fdt32_to_cpu(val):
+ """Convert a device tree cell to an integer
+
+ Args:
+ Value to convert (4-character string representing the cell value)
+
+ Return:
+ A native-endian integer value
+ """
+ return struct.unpack(">I", val)[0]
projects / u-boot / commitdiff