(factory-2460.B)vboot_reference: add "set_gbb_flags" script.

A simple script to help setting GBB flags on-the-fly, with help information for
flag value meanings.

BUG=chrome-os-partner:10389
TEST=./set_gbb_flags.sh 0x20
     ./set_gbb_flags.sh 0x0

Reviewed-on: https://gerrit.chromium.org/gerrit/26224
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>

(cherry picked from commit 61603e2d6128d6fadd2fd8b1f16d60c5df8c00bd)

Change-Id: Ib63a813e35eb7b254411e3d64f4c71f41e51b817
Reviewed-on: https://gerrit.chromium.org/gerrit/27435
Reviewed-by: Jay Kim <yongjaek@chromium.org>
Tested-by: Jay Kim <yongjaek@chromium.org>
diff --git a/scripts/image_signing/set_gbb_flags.sh b/scripts/image_signing/set_gbb_flags.sh
new file mode 100755
index 0000000..bb23149
--- /dev/null
+++ b/scripts/image_signing/set_gbb_flags.sh
@@ -0,0 +1,76 @@
+#!/bin/sh
+#
+# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+#
+# This script can change GBB flags in system live firmware or a given image
+# file.
+
+SCRIPT_BASE="$(dirname "$0")"
+. "$SCRIPT_BASE/common_minimal.sh"
+load_shflags || exit 1
+
+# DEFINE_string name default_value description flag
+DEFINE_string file "" "Path to firmware image. Default to system firmware." "f"
+
+# Globals
+# ----------------------------------------------------------------------------
+set -e
+
+# Values from vboot_reference/firmware/include/gbb_header.h
+GBBFLAGS_DESCRIPTION="
+  Defined flags (some values may be not supported by all systems):
+
+  GBB_FLAG_DEV_SCREEN_SHORT_DELAY     0x00000001
+  GBB_FLAG_LOAD_OPTION_ROMS           0x00000002
+  GBB_FLAG_ENABLE_ALTERNATE_OS        0x00000004
+  GBB_FLAG_FORCE_DEV_SWITCH_ON        0x00000008
+  GBB_FLAG_FORCE_DEV_BOOT_USB         0x00000010
+  GBB_FLAG_DISABLE_FW_ROLLBACK_CHECK  0x00000020
+
+  To get a developer-friendly device, try 0x11 (short_delay + boot_usb).
+  For factory-related tests (always DEV), try 0x39.
+"
+
+FLAGS_HELP="Changes ChromeOS Firmware GBB Flags value.
+
+  Usage: $0 [option_flags] GBB_FLAGS_VALUE
+  $GBBFLAGS_DESCRIPTION"
+
+FLASHROM_COMMON_OPT="-p internal:bus=spi"
+FLASHROM_READ_OPT="$FLASHROM_COMMON_OPT -i GBB -r"
+FLASHROM_WRITE_OPT="$FLASHROM_COMMON_OPT -i GBB --fast-verify -w"
+
+# Main
+# ----------------------------------------------------------------------------
+main() {
+  if [ "$#" != "1" ]; then
+    flags_help
+    exit 1
+  fi
+
+  local value="$(($1))"
+  local image_file="$FLAGS_file"
+
+  if [ -z "$FLAGS_file" ]; then
+    image_file="$(make_temp_file)"
+    flashrom $FLASHROM_READ_OPT "$image_file"
+  fi
+
+  # Process file
+  local old_value="$(gbb_utility -g --flags "$image_file")"
+  printf "Setting GBB flags from %s to 0x%x.." "$old_value" "$value" >&2
+  gbb_utility -s --flags="$value" "$image_file"
+
+  if [ -z "$FLAGS_file" ]; then
+    flashrom $FLASHROM_WRITE_OPT "$image_file"
+  fi
+}
+
+# Parse command line
+FLAGS "$@" || exit 1
+ORIGINAL_PARAMS="$@"
+eval set -- "$FLAGS_ARGV"
+
+main "$@"