dtoc: Add a way to create an Fdt object from a data block

Support creating an Fdt object without having to write the data to a file
first.

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

tools/dtoc/fdt.py

@@ -472,6 +472,20 @@ class Fdt:
             with open(self._fname) as fd:
                 self._fdt_obj = libfdt.Fdt(fd.read())
 
+    @staticmethod
+    def FromData(data):
+        """Create a new Fdt object from the given data
+
+        Args:
+            data: Device-tree data blob
+
+        Returns:
+            Fdt object containing the data
+        """
+        fdt = Fdt(None)
+        fdt._fdt_obj = libfdt.Fdt(bytearray(data))
+        return fdt
+
     def LookupPhandle(self, phandle):
         """Look up a phandle
 

tools/dtoc/test_fdt.py

@@ -407,6 +407,14 @@ class TestProp(unittest.TestCase):
         self.node.SetData('empty', '123')
         self.assertEqual('123', prop.bytes)
 
+    def testFromData(self):
+        dtb2 = fdt.Fdt.FromData(self.dtb.GetContents())
+        self.assertEqual(dtb2.GetContents(), self.dtb.GetContents())
+
+        self.node.AddEmptyProp('empty', 5)
+        self.dtb.Sync(auto_resize=True)
+        self.assertTrue(dtb2.GetContents() != self.dtb.GetContents())
+
 
 class TestFdtUtil(unittest.TestCase):
     """Tests for the fdt_util module