u-boot/board/boundary/nitrogen6x/6x_upgrade.txt

setenv stdout serial,vga
echo "check U-Boot" ;
setenv offset 0x400
if ${fs}load ${dtype} ${disk}:1 12000000 u-boot.imx || ${fs}load ${dtype} ${disk}:1 12000000 u-boot.nopadding ; then
      echo "read $filesize bytes from SD card" ;
      if sf probe || sf probe || \
	 sf probe 1 27000000 || sf probe 1 27000000 ; then
	   echo "probed SPI ROM" ;
           if sf read 0x12400000 $offset $filesize ; then
               if cmp.b 0x12000000 0x12400000 $filesize ; then
                   echo "------- U-Boot versions match" ;
               else
                   echo "Need U-Boot upgrade" ;
                   echo "Program in 5 seconds" ;
                   for n in 5 4 3 2 1 ; do
                        echo $n ;
                        sleep 1 ;
                   done
		   echo "erasing" ;
                   sf erase 0 0x50000 ;
		   # two steps to prevent bricking
		   echo "programming" ;
                   sf write 0x12000000 $offset $filesize ;
		   echo "verifying" ;
                   if sf read 0x12400000 $offset $filesize ; then
                       if cmp.b 0x12000000 0x12400000 $filesize ; then
                           while echo "---- U-Boot upgraded. reset" ; do
				sleep 120
			   done
                       else
                           echo "Read verification error" ;
                       fi
                   else
                        echo "Error re-reading EEPROM" ;
                   fi
               fi
           else
               echo "Error reading boot loader from EEPROM" ;
           fi
      else
           echo "Error initializing EEPROM" ;
      fi ;
else
     echo "No U-Boot image found on SD card" ;
fi