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>

lib/libfdt/libfdt.swig

@@ -0,0 +1,89 @@
+/* File: libfdt.i */
+%module libfdt
+
+%{
+#define SWIG_FILE_WITH_INIT
+#include "libfdt.h"
+%}
+
+%pythoncode %{
+def Raise(errnum):
+    raise ValueError('Error %s' % fdt_strerror(errnum))
+
+def Name(fdt, offset):
+    name, len = fdt_get_name(fdt, offset)
+    return name
+
+def String(fdt, offset):
+    offset = fdt32_to_cpu(offset)
+    name = fdt_string(fdt, offset)
+    return name
+
+def swap32(x):
+    return (((x << 24) & 0xFF000000) |
+            ((x <<  8) & 0x00FF0000) |
+            ((x >>  8) & 0x0000FF00) |
+            ((x >> 24) & 0x000000FF))
+
+def fdt32_to_cpu(x):
+    return swap32(x)
+
+def Data(prop):
+    set_prop(prop)
+    return get_prop_data()
+%}
+
+%include "typemaps.i"
+%include "cstring.i"
+
+%typemap(in) void* = char*;
+
+typedef int fdt32_t;
+
+struct fdt_property {
+        fdt32_t tag;
+        fdt32_t len;
+        fdt32_t nameoff;
+        char data[0];
+};
+
+/*
+ * This is a work-around since I'm not sure of a better way to copy out the
+ * contents of a string. This is used in dtoc/GetProps(). The intent is to
+ * pass in a pointer to a property and access the data field at the end of
+ * it. Ideally the Data() function above would be able to do this directly,
+ * but I'm not sure how to do that.
+ */
+#pragma SWIG nowarn=454
+%inline %{
+    static struct fdt_property *cur_prop;
+
+    void set_prop(struct fdt_property *prop) {
+        cur_prop = prop;
+    }
+%}
+
+%cstring_output_allocate_size(char **s, int *sz, free(*$1));
+%inline %{
+    void get_prop_data(char **s, int *sz) {
+        *sz = fdt32_to_cpu(cur_prop->len);
+        *s = (char *)malloc(*sz);
+        if (!*s)
+            *sz = 0;
+        else
+            memcpy(*s, cur_prop + 1, *sz);
+    }
+%}
+
+const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int checklen);
+int fdt_path_offset(const void *fdt, const char *path);
+int fdt_first_property_offset(const void *fdt, int nodeoffset);
+int fdt_next_property_offset(const void *fdt, int offset);
+const char *fdt_strerror(int errval);
+const struct fdt_property *fdt_get_property_by_offset(const void *fdt,
+                                                      int offset,
+                                                      int *OUTPUT);
+const char *fdt_get_name(const void *fdt, int nodeoffset, int *OUTPUT);
+const char *fdt_string(const void *fdt, int stroffset);
+int fdt_first_subnode(const void *fdt, int offset);
+int fdt_next_subnode(const void *fdt, int offset);

lib/libfdt/setup.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python
+
+"""
+setup.py file for SWIG libfdt
+"""
+
+from distutils.core import setup, Extension
+import os
+import sys
+
+# Don't cross-compile - always use the host compiler.
+del os.environ['CROSS_COMPILE']
+del os.environ['CC']
+
+progname = sys.argv[0]
+cflags = sys.argv[1]
+files = sys.argv[2:]
+
+if cflags:
+    cflags = [flag for flag in cflags.split(' ') if flag]
+else:
+    cflags = None
+
+libfdt_module = Extension(
+    '_libfdt',
+    sources = files,
+    extra_compile_args =  cflags
+)
+
+sys.argv = [progname, '--quiet', 'build_ext', '--inplace']
+
+setup (name = 'libfdt',
+       version = '0.1',
+       author      = "SWIG Docs",
+       description = """Simple swig libfdt from docs""",
+       ext_modules = [libfdt_module],
+       py_modules = ["libfdt"],
+       )

lib/libfdt/test_libfdt.py

@@ -0,0 +1,14 @@
+#!/usr/bin/python
+
+import os
+import sys
+
+our_path = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(our_path, '../../b/sandbox_spl/tools'))
+
+import libfdt
+
+with open('b/sandbox_spl/u-boot.dtb') as fd:
+    fdt = fd.read()
+
+print libfdt.fdt_path_offset(fdt, "/aliases")

scripts/Makefile.host

@@ -28,12 +28,16 @@ __hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))
 # C code
 # Executables compiled from a single .c file
 host-csingle	:= $(foreach m,$(__hostprogs), \
-			$(if $($(m)-objs)$($(m)-cxxobjs),,$(m)))
+			$(if $($(m)-objs)$($(m)-cxxobjs)$($(m)-sharedobjs),,$(m)))
 
 # C executables linked based on several .o files
 host-cmulti	:= $(foreach m,$(__hostprogs),\
 		   $(if $($(m)-cxxobjs),,$(if $($(m)-objs),$(m))))
 
+# Shared object libraries
+host-shared	:= $(foreach m,$(__hostprogs),\
+		   $(if $($(m)-sharedobjs),$(m))))
+
 # Object (.o) files compiled from .c files
 host-cobjs	:= $(sort $(foreach m,$(__hostprogs),$($(m)-objs)))
 
@@ -59,6 +63,7 @@ host-cmulti	:= $(addprefix $(obj)/,$(host-cmulti))
 host-cobjs	:= $(addprefix $(obj)/,$(host-cobjs))
 host-cxxmulti	:= $(addprefix $(obj)/,$(host-cxxmulti))
 host-cxxobjs	:= $(addprefix $(obj)/,$(host-cxxobjs))
+host-shared	:= $(addprefix $(obj)/,$(host-shared))
 host-objdirs    := $(addprefix $(obj)/,$(host-objdirs))
 
 obj-dirs += $(host-objdirs)
@@ -128,4 +133,4 @@ $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
 	$(call if_changed_dep,host-cxxobjs)
 
 targets += $(host-csingle)  $(host-cmulti) $(host-cobjs)\
-	   $(host-cxxmulti) $(host-cxxobjs)
+	   $(host-cxxmulti) $(host-cxxobjs) $(host-shared)

tools/Makefile

@@ -107,6 +107,17 @@ mkimage-objs   := $(dumpimage-mkimage-objs) mkimage.o
 fit_info-objs   := $(dumpimage-mkimage-objs) fit_info.o
 fit_check_sign-objs   := $(dumpimage-mkimage-objs) fit_check_sign.o
 
+hostprogs-$(CONFIG_SPL_OF_PLATDATA) += _libfdt.so
+_libfdt.so-sharedobjs += $(LIBFDT_OBJS)
+libfdt:
+
+tools/_libfdt.so: $(patsubst %.o,%.c,$(LIBFDT_OBJS)) tools/libfdt_wrap.c
+	python $(srctree)/lib/libfdt/setup.py "$(_hostc_flags)" $^
+	mv _libfdt.so $@
+
+tools/libfdt_wrap.c: $(srctree)/lib/libfdt/libfdt.swig
+	swig -python -o $@ $<
+
 # TODO(sjg@chromium.org): Is this correct on Mac OS?
 
 ifneq ($(CONFIG_MX23)$(CONFIG_MX28),)

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