U-Boot for TX53
                                        ===============

Building U-Boot
---------------

Note: There are currently two variants of the TX53 module, that
      require slightly different U-Boot configurations. They are
      distinguished through the last digit of the module name. Replace
      the '?' in the following description with the corresponding
      number from your TX51 module.
      E.g. TX53-8031 => 'make tx53-xx31_config'

Unpacking the source
--------------------
mkdir u-boot
cd u-boot
tar -xjf /cdrom/U-Boot/u-boot-src.tar.bz2

Compiling U-Boot
----------------
export ARCH=arm
export CROSS_COMPILE=arm-cortexa8-linux-gnueabi-
make tx53-xx3?_config            (see above Note!)
make


Flashing U-Boot Image
---------------------
If you want to replace a working U-Boot with a new version, you can
load the new U-Boot image via TFTP and program it like any other flash
partition with:
nand erase.part u-boot;nand write ${fileaddr} u-boot ${filesize}

If you want to revive a bricked module, you can use one of the
flashtools provided with the BSP to reprogram the flash.


U-Boot Features
---------------

Environment variables:

cpu_clk       <CPU freq [MHz]>
touchpanel    {tsc2007|edt-ft5x06}
otg_mode      [host|device|none]
video_mode    <video mode as understood by Linux fb_find_mode() function>
              e.g.: VGA-1:640x480MR-24@60
baseboard     {stk5-v3|stk5-v5} selects type of baseboard
	      'stk5-v5' setting enables CAN transceiver switch on GPIO4_21 and
	      disables USB Host mode on USBOTG port.
	      strings not starting in 'stk5' prevent the STK5 specific
	      pad initialization to be done.
splashimage   memory address of a BMP file to be displayed instead of
	      the built-in logo. Since NAND flash is not accessible in
	      a memory mapped fashion, U-Boot will try to load the
	      contents of the flash partition 'logo' to the address
	      given with 'splashimage'.

Note: Some variables (like 'cpu_clk' or 'splashimage') may render the
      board unbootable if incorrectly set. Therefore these variables
      will not be evaluated in case the board has been reset through a
      watchdog reset or a character is available on the serial console
      during startup to give the user a chance to recover from this
      situation.