U-Boot for LibreTech AC
=======================

LibreTech AC is a single board computer manufactured by Libre Technology
with the following specifications:

 - Amlogic S805X ARM Cortex-A53 quad-core SoC @ 1.2GHz
 - ARM Mali 450 GPU
 - 512MiB DDR4 SDRAM
 - 10/100 Ethernet
 - HDMI 2.0 4K/60Hz display
 - 40-pin GPIO header
 - 4 x USB 2.0 Host
 - eMMC, SPI NOR Flash
 - Infrared receiver

Schematics are available on the manufacturer website.

Currently the U-Boot port supports the following devices:
 - serial
 - eMMC
 - Ethernet
 - USB

U-Boot compilation
==================

 > export ARCH=arm
 > export CROSS_COMPILE=aarch64-none-elf-
 > make libretech-ac_defconfig
 > make

Image creation
==============

Amlogic doesn't provide sources for the firmware and for tools needed
to create the bootloader image, so it is necessary to obtain them from
the git tree published by the board vendor:

 > wget https://releases.linaro.org/archive/13.11/components/toolchain/binaries/gcc-linaro-aarch64-none-elf-4.8-2013.11_linux.tar.xz
 > wget https://releases.linaro.org/archive/13.11/components/toolchain/binaries/gcc-linaro-arm-none-eabi-4.8-2013.11_linux.tar.xz
 > tar xvfJ gcc-linaro-aarch64-none-elf-4.8-2013.11_linux.tar.xz
 > tar xvfJ gcc-linaro-arm-none-eabi-4.8-2013.11_linux.tar.xz
 > export PATH=$PWD/gcc-linaro-aarch64-none-elf-4.8-2013.11_linux/bin:$PWD/gcc-linaro-arm-none-eabi-4.8-2013.11_linux/bin:$PATH
 > git clone https://github.com/BayLibre/u-boot.git -b libretech-ac amlogic-u-boot
 > cd amlogic-u-boot
 > wget https://raw.githubusercontent.com/BayLibre/u-boot/libretech-cc/fip/blx_fix.sh
 > make libretech_ac_defconfig
 > make
 > export UBOOTDIR=$PWD

Download the latest Amlogic Buildroot package, and extract it :
 > wget http://openlinux2.amlogic.com:8000/ARM/filesystem/Linux_BSP/buildroot_openlinux_kernel_4.9_fbdev_20180418.tar.gz
 > tar xfz buildroot_openlinux_kernel_4.9_fbdev_20180418.tar.gz buildroot_openlinux_kernel_4.9_fbdev_20180418/bootloader
 > export BRDIR=$PWD/buildroot_openlinux_kernel_4.9_fbdev_20180418

Go back to mainline U-Boot source tree then :
 > mkdir fip

 > cp $UBOOTDIR/build/scp_task/bl301.bin fip/
 > cp $UBOOTDIR/build/board/amlogic/libretech_ac/firmware/bl21.bin fip/
 > cp $UBOOTDIR/build/board/amlogic/libretech_ac/firmware/acs.bin fip/
 > cp $BRDIR/bootloader/uboot-repo/bl2/bin/gxl/bl2.bin fip/
 > cp $BRDIR/bootloader/uboot-repo/bl30/bin/gxl/bl30.bin fip/
 > cp $BRDIR/bootloader/uboot-repo/bl31/bin/gxl/bl31.img fip/
 > cp u-boot.bin fip/bl33.bin

 > sh $UBOOTDIR/blx_fix.sh \
	fip/bl30.bin \
	fip/zero_tmp \
	fip/bl30_zero.bin \
	fip/bl301.bin \
	fip/bl301_zero.bin \
	fip/bl30_new.bin \
	bl30

 > $BRDIR/bootloader/uboot-repo/fip/acs_tool.pyc fip/bl2.bin fip/bl2_acs.bin fip/acs.bin 0

 > sh $UBOOTDIR/blx_fix.sh \
	fip/bl2_acs.bin \
	fip/zero_tmp \
	fip/bl2_zero.bin \
	fip/bl21.bin \
	fip/bl21_zero.bin \
	fip/bl2_new.bin \
	bl2

 > $BRDIR/bootloader/uboot-repo/fip/gxl/aml_encrypt_gxl --bl3enc --input fip/bl30_new.bin
 > $BRDIR/bootloader/uboot-repo/fip/gxl/aml_encrypt_gxl --bl3enc --input fip/bl31.img
 > $BRDIR/bootloader/uboot-repo/fip/gxl/aml_encrypt_gxl --bl3enc --input fip/bl33.bin
 > $BRDIR/bootloader/uboot-repo/fip/gxl/aml_encrypt_gxl --bl2sig --input fip/bl2_new.bin --output fip/bl2.n.bin.sig
 > $BRDIR/bootloader/uboot-repo/fip/gxl/aml_encrypt_gxl --bootmk \
		--output fip/u-boot.bin \
		--bl2 fip/bl2.n.bin.sig \
		--bl30 fip/bl30_new.bin.enc \
		--bl31 fip/bl31.img.enc \
		--bl33 fip/bl33.bin.enc

and then write the image to SD with:

 > DEV=/dev/your_sd_device
 > dd if=fip/u-boot.bin.sd.bin of=$DEV conv=fsync,notrunc bs=512 skip=1 seek=1
 > dd if=fip/u-boot.bin.sd.bin of=$DEV conv=fsync,notrunc bs=1 count=444