4.34. TI K3 AM62lx based boards

The TI AM62lx is SoC in the line of TI K3 64-bit ARM SoCs.

The boot process of the TI AM62x SoCs is a two step process. The first stage boot loader is loaded by the ROM code and executed on the Cortex-A53 processor. This stage contains some firmware files and a BL1 which is responsible for setting up the initial clocks, power domains and DRAM. When this is done the BL1 branches back to the ROM which loads the second stage which contains the TF-A BL31, barebox proper and optionally OP-TEE.

The AM62lx support currently depends on a modified downstream version of the TF-A. See https://lore.kernel.org/20250617090142.3000882-1-s.hauer@pengutronix.de for a patch series to be applied on the Downstream TF-A. Be aware that barebox might need further changes to be compatible with future upstream TF-A support. Specifically the SCMI clock IDs used in the assigned-clock-parents properties might not match the future upstream solution.

4.34.1. Building TF-A

The Arm Trusted Firmware is built from https://github.com/ARM-software/arm-trusted-firmware.git:

make CROSS_COMPILE=$CROSS_COMPILE_64 ARCH=aarch64 PLAT=k3 SPD=opteed \
      TARGET_BOARD=am62l
cp build/k3/am62l/release/bl1.bin $BAREBOX_SOURCE/firmware/am62lx-bl1.bin
cp build/k3/am62l/release/bl31.bin $BAREBOX_SOURCE/firmware/am62lx-bl31.bin

Note

As time of writing the AM62lx support is not yet supported in upstream TF-A. Build from https://github.com/TexasInstruments/arm-trusted-firmware.git 11.00.11 instead.

4.34.2. Bulding OP-TEE

OP-TEE is built from https://github.com/OP-TEE/optee_os.git:

make CROSS_COMPILE64=$CC64 CFG_ARM64_core=y CFG_WITH_SOFTWARE_PRNG=y \
      PLATFORM=k3-am62lx
cp out/arm-plat-k3/core/tee-raw.bin $BAREBOX_SOURCE/firmware/am62lx-bl32.bin

OP-TEE is optional. barebox will continue without OP-TEE when the file does not exist. In that case drop the SPD=opteed option above when building the TF-A

Note

As time of writing the AM62lx OP-TEE support has not yet landed in a release. Use the master branch for building OP-TEE

4.34.3. Building barebox

The am62lx images are built as part of the multi_v8_defconfig:

export ARCH=arm CROSS_COMPILE=CROSS_COMPILE_64
make multi_v8_defconfig
make
cp images/barebox-am62lx-evm-tiboot3.img $TI_BOOT/tiboot3.bin
cp images/barebox-am62lx-evm.img $TI_BOOT/tispl.bin

4.34.4. USB DFU boot

K3 Boards can be booted via USB DFU. When in USB boot mode the initial stage can be uploaded using dfu-util:

dfu-util -D images/barebox-am62lx-evm-tiboot3.img -a 0

This will start the initial stage which then expects the following stage which can be uploaded with dfu-util as well:

dfu-util -D images/barebox-am62lx-evm.img -a 0

4.34.5. eMMC boot

K3 boards can boot from eMMC boot partitions. In this mode the ROM reads the tiboot3.bin raw from the active boot partition. In this mode barebox expects the FIP image with the following stages in the same boot partition at offset 1MiB. There is a barebox update handler which takes a combined image consisting of tiboot3.bin and the FIP image to allow for a failsafe update. This image can’t be generated by the barebox build system though. It has to be generated by a build system or manually:

dd if=images/barebox-am62lx-evm-tiboot3.img of=barebox-am62lx-evm-emmc.img
dd if=images/barebox-am62lx-evm.img of=barebox-am62lx-evm-emmc.img bs=1024 seek=512