dtoc: Update Fdt.FromData() to allow a name

It is confusing when something goes wrong with a device tree which was
created from data rather than a file, since there is no identifying
filename. Add an option to provide this. Use the filename as the name,
where available

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

tools/dtoc/fdt.py

@@ -498,29 +498,35 @@ class Fdt:
     Properties:
       fname: Filename of fdt
       _root: Root of device tree (a Node object)
+      name: Helpful name for this Fdt for the user (useful when creating the
+        DT from data rather than a file)
     """
     def __init__(self, fname):
         self._fname = fname
         self._cached_offsets = False
         self.phandle_to_node = {}
+        self.name = ''
         if self._fname:
+            self.name = self._fname
             self._fname = fdt_util.EnsureCompiled(self._fname)
 
             with open(self._fname, 'rb') as fd:
                 self._fdt_obj = libfdt.Fdt(fd.read())
 
     @staticmethod
-    def FromData(data):
+    def FromData(data, name=''):
         """Create a new Fdt object from the given data
 
         Args:
             data: Device-tree data blob
+            name: Helpful name for this Fdt for the user
 
         Returns:
             Fdt object containing the data
         """
         fdt = Fdt(None)
         fdt._fdt_obj = libfdt.Fdt(bytes(data))
+        fdt.name = name
         return fdt
 
     def LookupPhandle(self, phandle):