dtoc: Support deleting device tree properties

Add support for deleting a device tree property. With the fallback
implementation this uses fdtput. With libfdt it uses the API call and
updates the offsets afterwards.

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

lib/libfdt/libfdt.swig

@@ -95,3 +95,15 @@ const char *fdt_get_name(const void *fdt, int nodeoffset, int *OUTPUT);
 const char *fdt_string(const void *fdt, int stroffset);
 int fdt_first_subnode(const void *fdt, int offset);
 int fdt_next_subnode(const void *fdt, int offset);
+
+%typemap(in) (void *) {
+  if (!PyByteArray_Check($input)) {
+    SWIG_exception_fail(SWIG_TypeError, "in method '" "$symname" "', argument "
+                       "$argnum"" of type '" "$type""'");
+  }
+  $1 = PyByteArray_AsString($input);
+}
+
+int fdt_delprop(void *fdt, int nodeoffset, const char *name);
+
+const char *fdt_strerror(int errval);

tools/dtoc/fdt.py

@@ -184,6 +184,16 @@ class NodeBase:
         """
         raise NotImplementedError()
 
+    def DeleteProp(self, prop_name):
+        """Delete a property of a node
+
+        This should be implemented by subclasses
+
+        Args:
+            prop_name: Name of the property to delete
+        """
+        raise NotImplementedError()
+
 class Fdt:
     """Provides simple access to a flat device tree blob.
 

tools/dtoc/fdt_fallback.py

@@ -70,6 +70,19 @@ class Node(NodeBase):
 
             node.Scan()
 
+    def DeleteProp(self, prop_name):
+        """Delete a property of a node
+
+        The property is deleted using fdtput.
+
+        Args:
+            prop_name: Name of the property to delete
+        Raises:
+            CommandError if the property does not exist
+        """
+        args = [self._fdt._fname, '-d', self.path, prop_name]
+        command.Output('fdtput', *args)
+        del self.props[prop_name]
 
 class FdtFallback(Fdt):
     """Provides simple access to a flat device tree blob using fdtget/fdtput

tools/dtoc/fdt_normal.py

@@ -20,6 +20,11 @@ import libfdt
 # This implementation uses a libfdt Python library to access the device tree,
 # so it is fairly efficient.
 
+def CheckErr(errnum, msg):
+    if errnum:
+        raise ValueError('Error %d: %s: %s' %
+            (errnum, libfdt.fdt_strerror(errnum), msg))
+
 class Prop(PropBase):
     """A device tree property
 
@@ -95,6 +100,21 @@ class Node(NodeBase):
             subnode.Refresh(offset)
             offset = libfdt.fdt_next_subnode(self._fdt.GetFdt(), offset)
 
+    def DeleteProp(self, prop_name):
+        """Delete a property of a node
+
+        The property is deleted and the offset cache is invalidated.
+
+        Args:
+            prop_name: Name of the property to delete
+        Raises:
+            ValueError if the property does not exist
+        """
+        CheckErr(libfdt.fdt_delprop(self._fdt.GetFdt(), self.Offset(), prop_name),
+                 "Node '%s': delete property: '%s'" % (self.path, prop_name))
+        del self.props[prop_name]
+        self._fdt.Invalidate()
+
 class FdtNormal(Fdt):
     """Provides simple access to a flat device tree blob using libfdt.