This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

WARNING: alpha quality software, read the instructions in the installation section.

This project fixes the U-Boot port published by Transcend in source format. The SD controller driver was broken, not allowing access from U-Boot and leaving the controller in an inconsistent state which prevented the Linux driver from working as well.

A few other improvements have been implemented. Look below for a complete list.

Note that this port is hacked in and held together by duct tape, but since the required functionality is quite limited, I don't think it would be worth the time to clean it up and merge it with a more recent U-Boot version.

You'll need to have an ARM toolchain set up. If you're cross-compiling on x86, you can use the one built by Linaro, Sourcery CodeBench, one provided by your distribution, etc.

If you're cross-compiling, you'll need to append the following string at the end of each command:

ARCH=arm CROSS_COMPILE=prefix-of-toolchain

Where prefix-of-toolchain will probably looks something like arm-none-eabi-.

Clean:

make distclean

Config:

make ka2000_config

Build:

make

WARNING: since this bootloader hasn't been tested thoroughly it is highly recommended that you set up an UART terminal for debugging. See this thread for the pinout.

• As a second stage bootloader

Because there's a possibility of bricking the ARM SoC part of the card each time the bootloader is flashed, it is highly recommended to simply use it as a second stage bootloader loaded from the SD card by the original U-Boot binary.

To do this, rename the u-boot.bin file produced by the build process to program.bin and copy it to the root of the FAT partition on your card.

• Flashing the device

WARNING: If you choose to install this version in the flash memory, be warned: automatic loading of program.bin has been disabled, which means that you will need an UART terminal to upgrade any of the bootloader, kernel, or rootfs images.

To flash u-boot.bin, copy it together with program.bin from one of the binary firmware upgrade packages to the root of the FAT partition on the card.

• Fixed the SD controller driver, which works in the binary release but not in the source release.
• Disabled automatic loading of program.bin, to prevent accidental flashing and to allow loading from the SD card of this version as a second stage bootloader (see installation as a second stage bootloader above) without entering a loop.
• Fix access to the SD from U-Boot when the device is simply powered on but not connected to an SD card reader. This will enable stand-alone use. Note that even though U-Boot now works in this case, the Transcend-provided Linux system doesn't. I'm working on this.

• While this version of U-Boot can run in stand-alone mode (with power applied but without the device being connected to an SD card reader), the Transcend-provided Linux system still doesn't work in that mode. I'm working on a fix.
• If an external card reader writes to the SD while u-boot is running, all subsequent SD operations from u-boot will fail. A power cycle is required.