dtoc: Update Fdt.GetNode() to handle the root node

This function currently fails if the root node is requested. Requesting
the root node is sometimes useful, so fix the bug.
Signed-off-by: NSimon Glass <sjg@chromium.org>

tools/dtoc/fdt.py

@@ -574,6 +574,8 @@ class Fdt:
         parts = path.split('/')
         if len(parts) < 2:
             return None
+        if len(parts) == 2 and parts[1] == '':
+            return node
         for part in parts[1:]:
             node = node.FindNode(part)
             if not node:

tools/dtoc/test_fdt.py

@@ -77,11 +77,16 @@ class TestFdt(unittest.TestCase):
         """Test the GetNode() method"""
         node = self.dtb.GetNode('/spl-test')
         self.assertTrue(isinstance(node, fdt.Node))
+
         node = self.dtb.GetNode('/i2c@0/pmic@9')
         self.assertTrue(isinstance(node, fdt.Node))
         self.assertEqual('pmic@9', node.name)
         self.assertIsNone(self.dtb.GetNode('/i2c@0/pmic@9/missing'))
 
+        node = self.dtb.GetNode('/')
+        self.assertTrue(isinstance(node, fdt.Node))
+        self.assertEqual(0, node.Offset())
+
     def testFlush(self):
         """Check that we can flush the device tree out to its file"""
         fname = self.dtb._fname