Create new cros_write_firmware tool based on write_tegra_bios.

host/share/cros_write_firmware/spi.script

Index: host/share/cros_write_firmware/spi.script
diff --git a/host/share/cros_write_firmware/spi.script b/host/share/cros_write_firmware/spi.script
new file mode 100644
index 0000000000000000000000000000000000000000..cba7cd180d952fae216bb95564d6a411ad05dc3e
--- /dev/null
+++ b/host/share/cros_write_firmware/spi.script
@@ -0,0 +1,16 @@
+setenv _crc    crc32 ${address} ${firmware_size}

[vb, 2011/03/04 00:58:31]

This is a u-boot script. Can you please put the command sequences in double
quotes.  This way semicolon escapes won't be needed.

[robotboy, 2011/03/04 16:58:57]

Done.

+setenv _init   echo Initing SPI\;  sf probe            0
+setenv _erase  echo Erasing SPI\;  sf erase            0 ${length}
+setenv _write  echo Writing SPI\;  sf write ${address} 0 ${length}
+setenv _clear  echo Clearing RAM\; mw.b     ${address} 0 ${length}
+setenv _read   echo Reading SPI\;  sf read  ${address} 0 ${length}
+
+run _crc
+run _init
+run _erase
+run _write
+run _clear
+run _read
+run _crc
+
+echo If the 2 CRCs above are equal, flash was successful