pylibfdt: Add support for fdt_subnode_offset()

Add this into the class to simplify use of this function.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

pylibfdt/libfdt.i

@@ -174,6 +174,23 @@ class Fdt:
         self._fdt = bytearray(data)
         check_err(fdt_check_header(self._fdt));
 
+    def subnode_offset(self, parentoffset, name, quiet=()):
+        """Get the offset of a named subnode
+
+        Args:
+            parentoffset: Offset of the parent node to check
+            name: Name of the required subnode, e.g. 'subnode@1'
+            quiet: Errors to ignore (empty to raise on all errors)
+
+        Returns:
+            The node offset of the found node, if any
+
+        Raises
+            FdtException if there is no node with that name, or other error
+        """
+        return check_err(fdt_subnode_offset(self._fdt, parentoffset, name),
+                         quiet)
+
     def path_offset(self, path, quiet=()):
         """Get the offset for a given path
 

tests/pylibfdt_tests.py

@@ -118,6 +118,18 @@ class PyLibfdtTests(unittest.TestCase):
             fdt = libfdt.Fdt('a string')
         self.assertEquals(e.exception.err, -libfdt.BADMAGIC)
 
+    def testSubnodeOffset(self):
+        """check that we can locate a subnode by name"""
+        node1 = self.fdt.path_offset('/subnode@1')
+        self.assertEquals(self.fdt.subnode_offset(0, 'subnode@1'), node1)
+
+        with self.assertRaises(FdtException) as e:
+            self.fdt.subnode_offset(0, 'missing')
+        self.assertEquals(e.exception.err, -libfdt.NOTFOUND)
+
+        node2 = self.fdt.path_offset('/subnode@1/subsubnode')
+        self.assertEquals(self.fdt.subnode_offset(node1, 'subsubnode'), node2)
+
     def testPathOffset(self):
         """Check that we can find the offset of a node"""
         self.assertEquals(self.fdt.path_offset('/'), 0)