binman: Correct fmap output on x86

Normally x86 platforms use the end-at-4gb option. This currently produces
an FMAP with positions which have a large offset. The use of end-at-4gb is
a useful convenience within binman, but we don't really want to export
a map with these offsets.

Fix this by subtracting the 'skip at start' parameter.

Also put the code which convers names to fmap format, for clarity.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index f8faef1..1abb768 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -1663,6 +1663,51 @@
         self.assertEqual('tplnodtb with microc' + pos_and_size +
                          'ter somewhere in here', first)
 
+    def testFmapX86(self):
+        """Basic test of generation of a flashrom fmap"""
+        data = self._DoReadFile('94_fmap_x86.dts')
+        fhdr, fentries = fmap_util.DecodeFmap(data[32:])
+        expected = U_BOOT_DATA + MRC_DATA + 'a' * (32 - 7)
+        self.assertEqual(expected, data[:32])
+        fhdr, fentries = fmap_util.DecodeFmap(data[32:])
+
+        self.assertEqual(0x100, fhdr.image_size)
+
+        self.assertEqual(0, fentries[0].offset)
+        self.assertEqual(4, fentries[0].size)
+        self.assertEqual('U_BOOT', fentries[0].name)
+
+        self.assertEqual(4, fentries[1].offset)
+        self.assertEqual(3, fentries[1].size)
+        self.assertEqual('INTEL_MRC', fentries[1].name)
+
+        self.assertEqual(32, fentries[2].offset)
+        self.assertEqual(fmap_util.FMAP_HEADER_LEN +
+                         fmap_util.FMAP_AREA_LEN * 3, fentries[2].size)
+        self.assertEqual('FMAP', fentries[2].name)
+
+    def testFmapX86Section(self):
+        """Basic test of generation of a flashrom fmap"""
+        data = self._DoReadFile('95_fmap_x86_section.dts')
+        expected = U_BOOT_DATA + MRC_DATA + 'b' * (32 - 7)
+        self.assertEqual(expected, data[:32])
+        fhdr, fentries = fmap_util.DecodeFmap(data[36:])
+
+        self.assertEqual(0x100, fhdr.image_size)
+
+        self.assertEqual(0, fentries[0].offset)
+        self.assertEqual(4, fentries[0].size)
+        self.assertEqual('U_BOOT', fentries[0].name)
+
+        self.assertEqual(4, fentries[1].offset)
+        self.assertEqual(3, fentries[1].size)
+        self.assertEqual('INTEL_MRC', fentries[1].name)
+
+        self.assertEqual(36, fentries[2].offset)
+        self.assertEqual(fmap_util.FMAP_HEADER_LEN +
+                         fmap_util.FMAP_AREA_LEN * 3, fentries[2].size)
+        self.assertEqual('FMAP', fentries[2].name)
+
 
 if __name__ == "__main__":
     unittest.main()