dm: Add a more efficient libfdt library
Add a Python version of the libfdt library which contains enough features to
support the dtoc tool. This is only a very bare-bones implementation. It
requires the 'swig' to build.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/dtoc/fdt.py b/tools/dtoc/fdt.py
new file mode 100644
index 0000000..1d913a9
--- /dev/null
+++ b/tools/dtoc/fdt.py
@@ -0,0 +1,180 @@
+#!/usr/bin/python
+#
+# Copyright (C) 2016 Google, Inc
+# Written by Simon Glass <sjg@chromium.org>
+#
+# SPDX-License-Identifier: GPL-2.0+
+#
+
+import fdt_util
+import libfdt
+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 a libfdt Python library to access the device tree,
+# so it is fairly efficient.
+
+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, bytes):
+ self.name = name
+ self.value = None
+ if not bytes:
+ self.type = fdt_util.TYPE_BOOL
+ self.value = True
+ return
+ self.type, self.value = fdt_util.BytesToValue(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 = [self.value]
+
+ if type(self.value) == list and len(newprop.value) > len(self.value):
+ val = fdt_util.GetEmpty(self.type)
+ while len(self.value) < len(newprop.value):
+ self.value.append(val)
+
+
+class Node:
+ """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):
+ self.offset = offset
+ 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.
+ """
+ self.props = self._fdt.GetProps(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)
+
+
+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
+ with open(fname) as fd:
+ self._fdt = fd.read()
+
+ def GetFdt(self):
+ """Get the contents of the FDT
+
+ Returns:
+ The FDT contents as a string of bytes
+ """
+ return self._fdt
+
+ 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, 0, '/', '/')
+ self._root.Scan()
+
+ def GetRoot(self):
+ """Get the root Node of the device tree
+
+ Returns:
+ The root Node object
+ """
+ return self._root
+
+ 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.
+ """
+ offset = libfdt.fdt_path_offset(self._fdt, node)
+ 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(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