U-Boot

Important Notice

We're not using U-Boot in this release. But during the R&D phase, the U-Boot is very convenient to use. The information below is left here just for your reference.

Introduction

Das U-Boot - the Universal Boot Loader WIKI Website is the main entry point for this bootloader / debugging tool available on several processors. It is of course available for AT91 ARM processors.

Details of U-Boot are available in http://www.at91.com/linux4sam/bin/view/Linux4SAM/U-Boot , where you can find the guide on how to use U-Boot.

Pre-built Images

U-Boot 1.3.4 (1.3.4-exp.5.patch)
Board	Description	Binary
at91sam9m10-g45-ek	U-Boot binary for AT91SAM9M10 MCU	u-boot-1.3.4-exp.5-at91sam9m10g45ek-sam9m10_nandflash.bin
at91sam9m10-g45-ek	U-Boot binary for AT91SAM9G45 MCU	u-boot-1.3.4-exp.5-at91sam9m10g45ek-sam9g45_nandflash.bin

Load U-Boot on AT91EK Boards

This section describes how to load U-Boot into the boot media with SAM-BA on AT91SAM9M10-G45-EK.

• Connect the USB Device Interface to your host machine using the USB Device Cable
• Make sure that the chip can execute the bootROM monitor SAM-BA-boot :
• Check and conform to the Default Jumpers Settings
• JP8 must be opened (BMS=1) to boot from the on-chip Boot ROM
• Remove NAND Flash Jumper (JP10)
• Power up the board
• Verify that the USB connection is established (ATMEL AT91xxxxx Test Board appears in taskbar notification area)
• Close NAND Flash Jumper (JP10)
• Start SAM-BA GUI Application
• Select the the board in the drop-down menu and choose the USB Connection

  

• Eventually plug back a jumper to access the media on which U-Boot must be loaded to
• In the main SAM-BA window :

  

1. Choose the proper media tab (NandFlash.) in the SAM-BA GUI interface
2. Initialize the media choosing the Enable action in the Scripts rolling menu and press Execute
3. Press on Send File Name Browse button
4. Choose u-boot.bin binary file and press Open
5. Enter the proper address on media in the Address text field. You can find a media map for each product in Android4SAM NandFlash demo Memory
6. Press Send File button
7. Close SAM-BA, remove the USB cable

Now you should have a running U-Boot flashed on your board. To verify, you can have a look at the DBGU serial interface once you have reset the board.

Build U-Boot From Source Code

To build U-Boot from source code, please go through the following steps.

Getting U-Boot Source Code

Dedicated page on U-Boot wiki : http://www.denx.de/wiki/U-Boot/SourceCode

To get the U-Boot bootloader sources for AT91 products, let's take U-Boot 1.3.4 as an example

• Download the u-boot sources from the link in the second below and extract it:

      wget ftp://ftp.denx.de/pub/u-boot/u-boot-1.3.4.tar.bz2
      tar xvjf u-boot-1.3.4.tar.bz2
      cd u-boot-1.3.4

Get ATMEL U-Boot Patch

• Take the corresponding AT91 U-Boot patch set

      wget ftp://www.at91.com/pub/uboot/u-boot-1.3.4-exp.5/u-boot-1.3.4-exp.5.diff

• Apply it on top of the original U-Boot code

      cat u-boot-1.3.4-exp.5.diff | patch -p1

Get Android U-Boot Patch

• Download U-boot patch for Android set

    wget ftp://ftp.linux4sam.org/pub/Android4SAM/9m10g45/v1.1/patches/u-boot-1.3.4-exp.5-Android-2.1_r2-ver1.1.diff

• Apply it on top of the original U-Boot code

      cat u-boot-1.3.4-exp.5-android-2.1_r2-ver1.1.diff | patch -p1

Choosing Proper Configuration

Modify the location of the U-Boot environmen to your needs :

Please go to the top-level Makefile or read the README.at91 file in the doc directory of U-Boot to find the exact target when invoking make.

To put environment variables in nandflash:

   make at91sam9xxxek_nandflash_config

Please go to the top-level Makefile or read the README.at91 file in the doc directory of U-Boot to find the exact target when invoking make.

Cross-compiling U-Boot

Once the AT91 u-boot sources available, cross-compile U-Boot is made in two steps : configuration and compiling. Check the Configuration chapter in U-Boot reference manual.

Note that both arm-elf- and arm-linux- ARM GCC cross-compiler types are suitable for U-Boot building.

  make distclean

For AT91SAM9M10-G45-EK board with AT91SAM9G45 MCU:

  make at91sam9g45ekes_nandflash_config
  make CROSS_COMPILE=<path_to_cross-compiler/cross-compiler-prefix->

For AT91SAM9M10-G45-EK board with AT91SAM9M10 MCU

  make at91sam9m10g45ek_nandflash_config
  make CROSS_COMPILE=<path_to_cross-compiler/cross-compiler-prefix->

path_to_cross-compiler is only needed if it is not in your PATH.
Usually cross-compiler-prefix- looks like arm-linux- or arm-elf-

The result includes several binary files. Two import files are

• u-boot.bin is the file you should store on the board
• u-boot is the ELF format binary file you may use to debug U-Boot through a JTag link for instance.

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See also: LinuxKernel

Load U-Boot on AT91EK Boards

This section describes how to load U-Boot into the boot media with SAM-BA on AT91SAM9M10-G45-EK.