dtoc: Allow the device tree to be compiled from source

If a source device tree is provide to the Fdt() constructors, compile it
automatically. This will be used in tests, where we want to build a
particular test .dts file and check that it works correctly in binman.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/dtoc/fdt_fallback.py

@@ -80,6 +80,8 @@ class FdtFallback(Fdt):
 
     def __init__(self, fname):
         Fdt.__init__(self, fname)
+        if self._fname:
+            self._fname = fdt_util.EnsureCompiled(self._fname)
 
     def GetSubNodes(self, node):
         """Returns a list of sub-nodes of a given node

tools/dtoc/fdt_normal.py

@@ -83,8 +83,11 @@ class FdtNormal(Fdt):
     """
     def __init__(self, fname):
         Fdt.__init__(self, fname)
-        with open(self._fname) as fd:
+        if self._fname:
-            self._fdt = fd.read()
+            self._fname = fdt_util.EnsureCompiled(self._fname)
+
+            with open(self._fname) as fd:
+                self._fdt = fd.read()
 
     def GetFdt(self):
         """Get the contents of the FDT

tools/dtoc/fdt_util.py

@@ -6,7 +6,12 @@
 # SPDX-License-Identifier:      GPL-2.0+
 #
 
+import os
 import struct
+import tempfile
+
+import command
+import tools
 
 def fdt32_to_cpu(val):
     """Convert a device tree cell to an integer
@@ -18,3 +23,39 @@ def fdt32_to_cpu(val):
         A native-endian integer value
     """
     return struct.unpack(">I", val)[0]
+
+def EnsureCompiled(fname):
+    """Compile an fdt .dts source file into a .dtb binary blob if needed.
+
+    Args:
+        fname: Filename (if .dts it will be compiled). It not it will be
+            left alone
+
+    Returns:
+        Filename of resulting .dtb file
+    """
+    _, ext = os.path.splitext(fname)
+    if ext != '.dts':
+        return fname
+
+    dts_input = tools.GetOutputFilename('source.dts')
+    dtb_output = tools.GetOutputFilename('source.dtb')
+
+    search_paths = [os.path.join(os.getcwd(), 'include')]
+    root, _ = os.path.splitext(fname)
+    args = ['-E', '-P', '-x', 'assembler-with-cpp', '-D__ASSEMBLY__']
+    args += ['-Ulinux']
+    for path in search_paths:
+        args.extend(['-I', path])
+    args += ['-o', dts_input, fname]
+    command.Run('cc', *args)
+
+    # If we don't have a directory, put it in the tools tempdir
+    search_list = []
+    for path in search_paths:
+        search_list.extend(['-i', path])
+    args = ['-I', 'dts', '-o', dtb_output, '-O', 'dtb']
+    args.extend(search_list)
+    args.append(dts_input)
+    command.Run('dtc', *args)
+    return dtb_output