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")