binman: Support an entry that holds text

It is useful to able to write an identifying string to the image within an
entry. Add a 'text' entry type to handle this. The actual text is
typically passed to binman on the command line. The text is not itself
nul-terminated but this can be achieved if required by setting the size of
the entry to something larger than the text.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index c54cd12..6968896 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -41,6 +41,9 @@
 CMC_DATA              = 'cmc'
 VBT_DATA              = 'vbt'
 MRC_DATA              = 'mrc'
+TEXT_DATA             = 'text'
+TEXT_DATA2            = 'text2'
+TEXT_DATA3            = 'text3'
 
 class TestFunctional(unittest.TestCase):
     """Functional tests for binman
@@ -1161,6 +1164,19 @@
         self.assertIn('GetArg() internal error: Unknown data type ',
                       str(e.exception))
 
+    def testText(self):
+        """Test for a text entry type"""
+        entry_args = {
+            'test-id': TEXT_DATA,
+            'test-id2': TEXT_DATA2,
+            'test-id3': TEXT_DATA3,
+        }
+        data, _, _, _ = self._DoReadFileDtb('66_text.dts',
+                                            entry_args=entry_args)
+        expected = (TEXT_DATA + chr(0) * (8 - len(TEXT_DATA)) + TEXT_DATA2 +
+                    TEXT_DATA3 + 'some text')
+        self.assertEqual(expected, data)
+
 
 if __name__ == "__main__":
     unittest.main()