AT91Bootstrap Project

AT91Bootstrap is the 2nd level bootloader for Atmel SMART microprocessors (aka AT91). It providing a set of algorithms to manage the hardware initialization such as clock speed configuration, PIO settings, DRAM initialization, to download your main application from specified boot media: NAND FLASH, serial FLASH (both AT25-compatible of DataFlash), serial EEPROM, SD Card, etc. to main memory and to start it.

1 GNU ARM Toolchain

AT91Bootstrap has been compiled and tested under Linux using the following GNU ARM Toolchain:

• gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
• gcc version 4.7.3 (Sourcery CodeBench Lite 2013.05-24)
• gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)
• gcc version 4.8.3 (Sourcery CodeBench Lite 2014.05-29)
• gcc version 4.9.3 (Linaro GCC 2014.11)
• gcc version 5.1.1 (Linaro GCC 5.1-2015.08)
• gcc version 7.2.1 (Linaro GCC 7.2-2017.11)
• gcc version 7.3.1 (Linaro GCC 7.2-2018.05)
• gcc version 8.2.0 (Ubuntu 8.2.0-7ubuntu1)

WARNING: check KNOWN_ISSUES for issues with older gcc versions. We recommend using a toolchain newer than 6.0.

2 Compile AT91Bootstrap

2.1 Compile DataFlashBoot

Let's use at91sam9x5ek as an example.

2.1.1 Compile booting u-boot image from DataFlash

$ cd <project directory>
$ make mrproper
$ make at91sam9x5ekdf_uboot_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

2.1.2 Compile booting kernel image from DataFlash

$ cd <project directory>
$ make mrproper
$ make at91sam9x5ekdf_linux_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

2.1.3 Compile booting kernel & dt image from DataFlash

$ cd <project directory>
$ make mrproper
$ make at91sam9x5ekdf_linux_dt_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

2.2 Compile NandFlashBoot

Let's use at91sam9m10g45ek as an example.

2.2.1 Compile booting u-boot image from NandFlash

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eknf_uboot_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

2.2.2 Compile booting kernel image from NandFlash

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eknf_linux_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

2.2.3 Compile booting kernel & dt image from NandFlash

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eknf_linux_dt_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

2.3 Compile SDCardBoot

Let's use at91sam9m10g45ek as an example,

2.3.1 Compile booting u-boot image from SDCard

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eksd_uboot_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

2.3.2 Compile booting linux image from SDCard

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eksd_linux_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

2.3.3 Compile booting linux & dt image from SDCard

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eksd_linux_dt_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

3 Release

If you plan to release the project, you can use the command as below

$ cd <project directory>
$ make tarball

If the command is successful, the .tar.gz tar package can be found under the project top directory.

4 Others

4.1 About booting from NOR flash.

4.1.1 ROM Code version

Booting from the external NOR flash is supported in ROM code v2.1 for SAMA5D3x. Bootstrap relocates the binary to the internal SRAM and run.

4.1.2 SAM-BA

Using SAM-BA to program the binary to the NOR flash is a little different from other booting mode. Namely, there is no 'Send Boot File' command for NOR flash.

You should use 'Send File' command to send the binary file the same like for a normal file, with 'Address' selected to 0.

5 Contributing your own board

If the system board that you have is not listed, then you will need to port AT91Bootstrap to your hardware platform. To do this, follow these steps:

1. Create a new directory to hold your board specific code under contrib/board/ directory. Add any files you need.
In your board directory, you will need at least the "board.mk", a ".c", ".h", "Config.in.board", and "Config.in.boardname".
2. Create the necessary default configuration files such as "df_uboot_defconfig" in your new board directory.
3. Add(source) your board's "Config.in.board" in "contrib/board/Config.in.board" file.
4. Add(source) your board's "Config.in.boardname" in the "contrib/board/Config.in.boardname" file.
5. Add your board's ".h" in the "contrib/include/contrib_board.h" file.
6. Run "make df_uboot_defconfig" with your new name.
7. Type "make", and you should get the final .bin image can be found under the binaries/ directory.

6 Contributing

To contribute to AT91Bootstrap you should submit the patches for review to the github pull-request facility directly or the forum. And don't forget to Cc the maintainers.

AT91 Forum:

http://www.at91.com/discussions/

Maintainers:

Eugen Hristev eugen.hristev@microchip.com

Nicolas Ferre nicolas.ferre@microchip.com

When creating patches insert the [at91bootstrap] tag in the subject, for example use something like:

git format-patch -s --subject-prefix='at91bootstrap][PATCH' <origin>

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