U-Boot for TX51
                                        ===============

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

Note: There are currently six variants of the TX51 module, that
      require slightly different U-Boot configurations. They are
      distinguished through the first and last digit of the module
      name suffix. Replace the '?' in the following description with
      the corresponding numbers from your TX51 module.
      E.g. TX51-8021 => 'make tx51-8xx1_config'

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

Alternatively you can access the current source via the git repository:
git://git.kernelconcepts.de/karo-tx-uboot.git master


Compiling U-Boot
----------------
export ARCH=arm
export CROSS_COMPILE=arm-cortexa8-linux-gnueabi-
make tx51-?xx?_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 disables USB Host mode on USBOTG port.
	      strings not starting in 'stk5' prevent the STK5 specific
	      pad initialization to be done.
splashimage   either: memory address (e.g. ${loadaddr}) 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.bmp' to the address given with
	      'splashimage'.

	      or: the name of an MTD partition, that contains a raw
	      dump of the frame buffer contents which will be loaded
	      to the framebuffer.

splashpos     (when 'splashimage' contains a memory address) the
	      position ('x,y') on the screen at which the BMP image
	      will be displayed.
	      Setting splashpos to 'm,m' will center the image on the
	      screen.

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.