enhance pack_firmware_image

* including fmap header in fmap areas
* initializing blobs by string value

BUG=chromium-os:15633
TEST=emerge-tegra2_{seaboard,kaen} chromeos-bios

Change-Id: Ib87a3f60fb11804888c4bc023d595629e017f589
Reviewed-on: http://gerrit.chromium.org/gerrit/1427
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Che-Liang Chiou <clchiou@chromium.org>

utility/pack_firmware_image

@@ -80,7 +80,17 @@ class Entry(dict):
     raise PackError('class Entry does not implement Pack()')
 
 
-class EntryFmap(Entry):
+class EntryFmapArea(Entry):
+
+  def __init__(self, **kwargs):
+    Entry._CheckFields(kwargs, ('flags',))
+    super(EntryFmapArea, self).__init__(**kwargs)
+
+  def Pack(self, firmware_image, entries):
+    pass
+
+
+class EntryFmap(EntryFmapArea):
 
   def __init__(self, **kwargs):
     Entry._CheckFields(kwargs, ('ver_major', 'ver_minor', 'base', 'size'))
@@ -90,9 +100,8 @@ class EntryFmap(Entry):
     # prepare header areas
     areas = []
     for e in entries:
-      if isinstance(e, EntryFmapArea):
-        areas.append(dict((name, e[name] if name != 'size' else e['length'])
-                          for name in FMAP_AREA_NAMES))
+      areas.append(dict((name, e[name] if name != 'size' else e['length'])
+                        for name in FMAP_AREA_NAMES))
 
     # prepare header
     obj = {'areas':areas}
@@ -114,16 +123,6 @@ class EntryFmap(Entry):
     firmware_image.write(blob)
 
 
-class EntryFmapArea(Entry):
-
-  def __init__(self, **kwargs):
-    Entry._CheckFields(kwargs, ('flags',))
-    super(EntryFmapArea, self).__init__(**kwargs)
-
-  def Pack(self, firmware_image, entries):
-    pass
-
-
 class EntryWiped(EntryFmapArea):
 
   def __init__(self, **kwargs):
@@ -147,6 +146,20 @@ class EntryWiped(EntryFmapArea):
     firmware_image.write(self.wipe_value * self.length)
 
 
+class EntryBlobString(EntryFmapArea):
+
+  def __init__(self, **kwargs):
+    Entry._CheckFields(kwargs, ('value',))
+    super(EntryBlobString, self).__init__(**kwargs)
+
+  def Pack(self, firmware_image, entries):
+    if len(self.value) > self.length:
+      raise PackError('string too large: len(%s) > %d' %
+                      (self.value, self.length))
+    firmware_image.seek(self.offset)
+    firmware_image.write(self.value)
+
+
 class EntryBlob(EntryFmapArea):
 
   def __init__(self, **kwargs):