pylibfdt: move pylibfdt to scripts/dtc/pylibfdt and refactor makefile

The pylibfdt is used by dtoc (and, indirectly by binman), but there
is no reason why it must be generated in the tools/ directory.

Recently, U-Boot switched over to the bundled DTC, and the directory
structure under scripts/dtc/ now mirrors the upstream DTC project.
So, scripts/dtc/pylibfdt is the best location.

I also rewrote the Makefile in a cleaner Kbuild style.

The scripts from the upstream have been moved as follows:

  lib/libfdt/pylibfdt/setup.py -> scripts/dtc/pylibfdt/setup.py
  lib/libfdt/pylibfdt/libfdt.i -> scripts/dtc/pylibfdt/libfdt.i_shipped

The .i_shipped is coped to .i during building because the .i must be
located in the objtree when we build it out of tree.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/dtc/pylibfdt/setup.py

@@ -0,0 +1,123 @@
+#!/usr/bin/env python
+
+"""
+setup.py file for SWIG libfdt
+Copyright (C) 2017 Google, Inc.
+Written by Simon Glass <sjg@chromium.org>
+
+SPDX-License-Identifier:	GPL-2.0+ BSD-2-Clause
+
+Files to be built into the extension are provided in SOURCES
+C flags to use are provided in CPPFLAGS
+Object file directory is provided in OBJDIR
+Version is provided in VERSION
+
+If these variables are not given they are parsed from the Makefiles. This
+allows this script to be run stand-alone, e.g.:
+
+    ./pylibfdt/setup.py install [--prefix=...]
+"""
+
+from distutils.core import setup, Extension
+import os
+import re
+import sys
+
+# Decodes a Makefile assignment line into key and value (and plus for +=)
+RE_KEY_VALUE = re.compile('(?P<key>\w+) *(?P<plus>[+])?= *(?P<value>.*)$')
+
+
+def ParseMakefile(fname):
+    """Parse a Makefile to obtain its variables.
+
+    This collects variable assigments of the form:
+
+        VAR = value
+        VAR += more
+
+    It does not pick out := assignments, as these are not needed here. It does
+    handle line continuation.
+
+    Returns a dict:
+        key: Variable name (e.g. 'VAR')
+        value: Variable value (e.g. 'value more')
+    """
+    makevars = {}
+    with open(fname) as fd:
+        prev_text = ''  # Continuation text from previous line(s)
+        for line in fd.read().splitlines():
+          if line and line[-1] == '\\':  # Deal with line continuation
+            prev_text += line[:-1]
+            continue
+          elif prev_text:
+            line = prev_text + line
+            prev_text = ''  # Continuation is now used up
+          m = RE_KEY_VALUE.match(line)
+          if m:
+            value = m.group('value') or ''
+            key = m.group('key')
+
+            # Appending to a variable inserts a space beforehand
+            if 'plus' in m.groupdict() and key in makevars:
+              makevars[key] += ' ' + value
+            else:
+              makevars[key] = value
+    return makevars
+
+def GetEnvFromMakefiles():
+    """Scan the Makefiles to obtain the settings we need.
+
+    This assumes that this script is being run from the top-level directory,
+    not the pylibfdt directory.
+
+    Returns:
+        Tuple with:
+            List of swig options
+            Version string
+            List of files to build
+            List of extra C preprocessor flags needed
+            Object directory to use (always '')
+    """
+    basedir = os.path.dirname(os.path.dirname(os.path.abspath(sys.argv[0])))
+    swig_opts = ['-I%s' % basedir]
+    makevars = ParseMakefile(os.path.join(basedir, 'Makefile'))
+    version = '%s.%s.%s' % (makevars['VERSION'], makevars['PATCHLEVEL'],
+                            makevars['SUBLEVEL'])
+    makevars = ParseMakefile(os.path.join(basedir, 'libfdt', 'Makefile.libfdt'))
+    files = makevars['LIBFDT_SRCS'].split()
+    files = [os.path.join(basedir, 'libfdt', fname) for fname in files]
+    files.append('pylibfdt/libfdt.i')
+    cflags = ['-I%s' % basedir, '-I%s/libfdt' % basedir]
+    objdir = ''
+    return swig_opts, version, files, cflags, objdir
+
+
+progname = sys.argv[0]
+files = os.environ.get('SOURCES', '').split()
+cflags = os.environ.get('CPPFLAGS', '').split()
+objdir = os.environ.get('OBJDIR')
+version = os.environ.get('VERSION')
+swig_opts = os.environ.get('SWIG_OPTS', '').split()
+
+# If we were called directly rather than through our Makefile (which is often
+# the case with Python module installation), read the settings from the
+# Makefile.
+if not all((swig_opts, version, files, cflags, objdir)):
+    swig_opts, version, files, cflags, objdir = GetEnvFromMakefiles()
+
+libfdt_module = Extension(
+    '_libfdt',
+    sources = files,
+    extra_compile_args = cflags,
+    swig_opts = swig_opts,
+)
+
+setup(
+    name='libfdt',
+    version= version,
+    author='Simon Glass <sjg@chromium.org>',
+    description='Python binding for libfdt',
+    ext_modules=[libfdt_module],
+    package_dir={'': objdir},
+    py_modules=['pylibfdt/libfdt'],
+)