pylibfdt: Add a means to add and delete notes

These methods are needed to permit larger changes to the device tree blob.
Add two new methods and an associate test.

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

pylibfdt/libfdt.i

@@ -689,6 +689,35 @@ class Fdt(FdtRo):
         """
         return check_err(fdt_delprop(self._fdt, nodeoffset, prop_name), quiet)
 
+    def add_subnode(self, parentoffset, name, quiet=()):
+        """Add a new subnode to a node
+
+        Args:
+            parentoffset: Parent offset to add the subnode to
+            name: Name of node to add
+
+        Returns:
+            offset of the node created, or negative error code on failure
+
+        Raises:
+            FdtError if there is not enough space, or another error occurs
+        """
+        return check_err(fdt_add_subnode(self._fdt, parentoffset, name), quiet)
+
+    def del_node(self, nodeoffset, quiet=()):
+        """Delete a node
+
+        Args:
+            nodeoffset: Offset of node to delete
+
+        Returns:
+            Error code, or 0 if OK
+
+        Raises:
+            FdtError if an error occurs
+        """
+        return check_err(fdt_del_node(self._fdt, nodeoffset), quiet)
+
 
 class Property(bytearray):
     """Holds a device tree property name and value.

tests/pylibfdt_tests.py

@@ -139,6 +139,24 @@ class PyLibfdtBasicTests(unittest.TestCase):
             poffset = self.fdt.next_property_offset(poffset, QUIET_NOTFOUND)
         return prop_list
 
+    def GetSubnodes(self, node_path):
+        """Read a list of subnodes from a node
+
+        Args:
+            node_path: Full path to node, e.g. '/subnode@1/subsubnode'
+
+        Returns:
+            List of subnode names for that node, e.g. ['subsubnode', 'ss1']
+        """
+        subnode_list = []
+        node = self.fdt.path_offset(node_path)
+        offset = self.fdt.first_subnode(node, QUIET_NOTFOUND)
+        while offset > 0:
+            name = self.fdt.get_name(offset)
+            subnode_list.append(name)
+            offset = self.fdt.next_subnode(offset, QUIET_NOTFOUND)
+        return subnode_list
+
     def testImport(self):
         """Check that we can import the library correctly"""
         self.assertEquals(type(libfdt), types.ModuleType)
@@ -495,6 +513,19 @@ class PyLibfdtBasicTests(unittest.TestCase):
             self.fdt.set_name(node, 'name\0')
         self.assertIn('embedded nul', str(e.exception))
 
+    def testAddDeleteNodes(self):
+        """Test that we can add and delete nodes"""
+        node_name = '/subnode@1'
+        self.assertEquals(self.GetSubnodes(node_name), ['subsubnode', 'ss1'])
+        node = self.fdt.path_offset('%s/subsubnode' % node_name)
+        self.assertEquals(self.fdt.del_node(node, 'subsubnode'), 0)
+        self.assertEquals(self.GetSubnodes(node_name), ['ss1'])
+
+        node = self.fdt.path_offset(node_name)
+        offset = self.fdt.add_subnode(node, 'more')
+        self.assertTrue(offset > 0)
+        self.assertEquals(self.GetSubnodes(node_name), ['more', 'ss1'])
+
 
 class PyLibfdtSwTests(unittest.TestCase):
     """Test class for pylibfdt sequential-write DT creation