J721S2 and AM68 Platforms

Introduction:

The J721S2 family of SoCs are part of K3 Multicore SoC architecture platform targeting automotive applications. They are designed as a low power, high performance and highly integrated device architecture, adding significant enhancement on processing power, graphics capability, video and imaging processing, virtualization and coherent memory support.

The AM68 Starter Kit/Evaluation Module (EVM) is based on the J721S2 family of SoCs. They are designed for machine vision, traffic monitoring, retail automation, and factory automation.

The device is partitioned into three functional domains, each containing specific processing cores and peripherals:

Wake-up (WKUP) domain:
- ARM Cortex-M4F processor, runs TI Foundational Security (TIFS)
Microcontroller (MCU) domain:
- Dual core ARM Cortex-R5F processor, runs device management and SoC early boot
MAIN domain:
- Dual core 64-bit ARM Cortex-A72, runs HLOS

More info can be found in TRM: https://www.ti.com/lit/pdf/spruj28

Platform information:

Boot Flow:

Below is the pictorial representation of boot flow:

On this platform, “TI Foundational Security” (TIFS) functions as the security enclave master while “Device Manager” (DM), also known as the “TISCI server” in TI terminology, offers all the essential services.
As illustrated in the diagram above, R5 SPL manages power and clock services independently before handing over control to “DM”. The A72 or the C7x (Aux core) software components request TIFS/DM to handle security or device management services.

Sources:

Das U-Boot

source: https://source.denx.de/u-boot/u-boot.git

branch: master
Trusted Firmware-A (TF-A)

source: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/

branch: master
Open Portable Trusted Execution Environment (OP-TEE)

source: https://github.com/OP-TEE/optee_os.git

branch: master
TI Firmware (TIFS, DM, SYSFW)

source: https://git.ti.com/git/processor-firmware/ti-linux-firmware.git

branch: ti-linux-firmware

Note

The TI Firmware required for functionality of the system can be one of the following combination (see platform specific boot diagram for further information as to which component runs on which processor):

TIFS - TI Foundational Security Firmware - Consists of purely firmware meant to run on the security enclave.

DM - Device Management firmware also called TI System Control Interface server (TISCI Server) - This component purely plays the role of managing device resources such as power, clock, interrupts, dma etc. This firmware runs on a dedicated or multi-use microcontroller outside the security enclave.

OR

SYSFW - System firmware - consists of both TIFS and DM both running on the security enclave.

Build procedure:

Setup the environment variables:

Generic environment variables
S/w Component	Env Variable	Description
All Software	CC32	Cross compiler for ARMv7 (ARM 32bit), typically arm-linux-gnueabihf-
All Software	CC64	Cross compiler for ARMv8 (ARM 64bit), typically aarch64-linux-gnu-
All Software	LNX_FW_PATH	Path to TI Linux firmware repository
All Software	TFA_PATH	Path to source of Trusted Firmware-A
All Software	OPTEE_PATH	Path to source of OP-TEE

Board specific environment variables
S/w Component	Env Variable	Description
U-Boot	UBOOT_CFG_CORTEXR	Defconfig for Cortex-R (Boot processor).
U-Boot	UBOOT_CFG_CORTEXA	Defconfig for Cortex-A (MPU processor).
Trusted Firmware-A	TFA_BOARD	Platform name used for building TF-A for Cortex-A Processor.
Trusted Firmware-A	TFA_EXTRA_ARGS	Any extra arguments used for building TF-A.
OP-TEE	OPTEE_PLATFORM	Platform name used for building OP-TEE for Cortex-A Processor.
OP-TEE	OPTEE_EXTRA_ARGS	Any extra arguments used for building OP-TEE.

Set the variables corresponding to this platform:

export CC32=arm-linux-gnueabihf-
export CC64=aarch64-linux-gnu-
export LNX_FW_PATH=path/to/ti-linux-firmware
export TFA_PATH=path/to/trusted-firmware-a
export OPTEE_PATH=path/to/optee_os

export UBOOT_CFG_CORTEXR=j721s2_evm_r5_defconfig
export UBOOT_CFG_CORTEXA=j721s2_evm_a72_defconfig
export TFA_BOARD=generic
export TFA_EXTRA_ARGS="K3_USART=0x8"
# The following is not a typo, j784s4 is the OP-TEE platform for j721s2
export OPTEE_PLATFORM=k3-j784s4
export OPTEE_EXTRA_ARGS="CFG_CONSOLE_UART=0x8"

Trusted Firmware-A:

# inside trusted-firmware-a source
make CROSS_COMPILE=$CC64 ARCH=aarch64 PLAT=k3 SPD=opteed $TFA_EXTRA_ARGS \
     TARGET_BOARD=$TFA_BOARD

OP-TEE:

# inside optee_os source
make CROSS_COMPILE=$CC32 CROSS_COMPILE64=$CC64 CFG_ARM64_core=y $OPTEE_EXTRA_ARGS \
      PLATFORM=$OPTEE_PLATFORM

U-Boot:

3.1 R5:

# inside u-boot source
make $UBOOT_CFG_CORTEXR
make CROSS_COMPILE=$CC32 BINMAN_INDIRS=$LNX_FW_PATH

3.2 A72:

# inside u-boot source
make $UBOOT_CFG_CORTEXA
make CROSS_COMPILE=$CC64 BINMAN_INDIRS=$LNX_FW_PATH \
       BL31=$TFA_PATH/build/k3/$TFA_BOARD/release/bl31.bin \
       TEE=$OPTEE_PATH/out/arm-plat-k3/core/tee-raw.bin

Note

It is also possible to pick up a custom DM binary by adding TI_DM argument pointing to the file. If not provided, it defaults to picking up the DM binary from BINMAN_INDIRS. This is only applicable to devices that utilize split firmware.

Target Images

In order to boot we need tiboot3.bin, tispl.bin and u-boot.img. Each SoC variant (GP, HS-FS, HS-SE) requires a different source for these files.

GP

tiboot3-j721s2-gp-evm.bin from step 3.1

tispl.bin_unsigned, u-boot.img_unsigned from step 3.2

HS-FS

tiboot3-j721s2-hs-fs-evm.bin from step 3.1

tispl.bin, u-boot.img from step 3.2

HS-SE

tiboot3-j721s2-hs-evm.bin from step 3.1

tispl.bin, u-boot.img from step 3.2

Image formats:

tiboot3.bin

tispl.bin

R5 Memory Map:

Region	Start Address	End Address
SPL	0x41c00000	0x41c40000
EMPTY	0x41c40000	0x41c61f20
STACK	0x41c65f20	0x41c61f20
Global data	0x41c65f20	0x41c66000
Heap	0x41c66000	0x41c76000
BSS	0x41c76000	0x41c80000
DM DATA	0x41c80000	0x41c84130
EMPTY	0x41c84130	0x41cff9fc
MCU Scratchpad	0x41cff9fc	0x41cffbfc
ROM DATA	0x41cffbfc	0x41cfffff

Switch Setting for Boot Mode

Boot Mode pins provide means to select the boot mode and options before the device is powered up. After every POR, they are the main source to populate the Boot Parameter Tables.

Boot Mode Pins for J721S2-EVM

The following table shows some common boot modes used on J721S2 platform. More details can be found in the Technical Reference Manual: https://www.ti.com/lit/pdf/spruj28 under the Boot Mode Pins section.

Boot Modes
Switch Label	SW9: 12345678	SW8: 12345678
SD	00000000	10000010
EMMC	01000000	10000000
OSPI	01000000	00000110
UART	01110000	00000000
USB DFU	00100000	10000000

For SW8 and SW9, the switch state in the “ON” position = 1.

Boot Mode Pins for SK-AM68

The following table shows some common boot modes used on AM68-SK platform. More details can be found in the User Guide for AM68-SK: https://www.ti.com/lit/pdf/spruj68 under the Bootmode Settings section.

Boot Modes
Switch Label	SW1: 1234
SD	0000
xSPI	0010
UART	1010
Ethernet	0100

For SW1, the switch state in the “ON” position = 1.

Debugging U-Boot

See Common Debugging environment - OpenOCD: for detailed setup information.

Warning

OpenOCD support since: v0.12.0

If the default package version of OpenOCD in your development environment’s distribution needs to be updated, it might be necessary to build OpenOCD from the source.

Debugging U-Boot on J721S2-EVM

Integrated JTAG adapter/dongle: The board has a micro-USB connector labelled XDS110 USB or JTAG. Connect a USB cable to the board to the mentioned port.

Note

There are multiple USB ports on a typical board, So, ensure you have read the user guide for the board and confirmed the silk screen label to ensure connecting to the correct port.

To start OpenOCD and connect to the board

openocd -f board/ti_j721s2evm.cfg

Debugging U-Boot on SK-AM68

cTI20 connector: The TI’s cTI20 connector is probably the most prevelant on TI platforms. Though many TI boards have an onboard XDS110, cTI20 connector is usually provided as an alternate scheme to connect alternatives such as Lauterbach or XDS560.

To debug on these boards, the following combinations is suggested:

TUMPA or equivalent dongles supported by OpenOCD.
Cable such as Tag-connect ribbon cable
Adapter to convert cTI20 to ARM20 such as those from Segger or Lauterbach LA-3780 Or optionally, if you have manufacturing capability then you could try BeagleBone JTAG Adapter

Warning

XDS560 and Lauterbach are proprietary solutions and is not supported by OpenOCD. When purchasing an off the shelf adapter/dongle, you do want to be careful about the signalling though. Please read for additional info.

External JTAG adapter/interface: In other cases, where an adapter/dongle is used, a simple cfg file can be created to integrate the SoC and adapter information. See supported TI K3 SoCs to decide if the SoC is supported or not.

openocd -f openocd_connect.cfg

For SK-AM68, the openocd_connect.cfg is as follows:

# TUMPA example:
# http://www.tiaowiki.com/w/TIAO_USB_Multi_Protocol_Adapter_User's_Manual
source [find interface/ftdi/tumpa.cfg]

transport select jtag

# default JTAG configuration has only SRST and no TRST
reset_config srst_only srst_push_pull

# delay after SRST goes inactive
adapter srst delay 20

if { ![info exists SOC] } {
  # Set the SoC of interest
  set SOC j721s2
}

source [find target/ti_k3.cfg]

ftdi tdo_sample_edge falling

# Speeds for FT2232H are in multiples of 2, and 32MHz is tops
# max speed we seem to achieve is ~20MHz.. so we pick 16MHz
adapter speed 16000