leverage flashrom fast partial read function to speed up VPD read.

include/lib/vpd.h

 /*
  * Copyright (C) 2010 Google Inc.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 2
  * of the License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 15 matching lines @@
 enum vpd_types {
   VPD_TYPE_FIRMWARE = 0,
   VPD_TYPE_SYSTEM,
   VPD_TYPE_END                  = 127,
   VPD_TYPE_BINARY_BLOB_POINTER  = 241,
 };
 
 /* The default RO VPD location in BIOS image.
  * If VPD partition cannot be found on fmap, buildEpsAndTables() will use
  * this value to count the offset fields of SPD and VPD 2.0.
- *
- * A user can specify -E argument to change the EPS base value. */
-#define GOOGLE_EPS_BASE 0x000000
+ * User can specify -E argument to change the EPS base value.
+ */
+#define GOOGLE_EPS_BASE 0xFFFFFFFF
+/* 0xFFFFFFFF is a special value, which is the value of a blank flash.
+ * It means we don't know the eps->table_address.
+ * This usually happens when we are creating a new VPD partition without
+ * knowing the flash topology (fmap). */
 
 #define GOOGLE_SPD_OFFSET 0x400
 #define GOOGLE_SPD_UUID "75f4926b-9e43-4b32-8979-eb20c0eda76a"
 #define GOOGLE_SPD_VENDOR "Google"
 #define GOOGLE_SPD_DESCRIPTION "Google SPD"
 #define GOOGLE_SPD_VARIANT ""
 
 #define GOOGLE_VPD_2_0_OFFSET 0x600
 #define GOOGLE_VPD_2_0_UUID "0a7c23d3-8a27-4252-99bf-7868a2e26b61"
 #define GOOGLE_VPD_2_0_VENDOR "Google"
 #define GOOGLE_VPD_2_0_DESCRIPTION "Google VPD 2.0"
 #define GOOGLE_VPD_2_0_VARIANT ""
 
 #define CONFIG_EPS_VPD_MAJOR_VERSION 2
 #define CONFIG_EPS_VPD_MINOR_VERSION 6
 
 #endif /* __LIB_VPD_H__ */