3.10. ARM Trusted Firmware-AΒΆ
Overview
Trusted Firmware-A (TF-A) provides a reference implementation of secure world software for Armv7-A and Armv8-A, including a Secure Monitor executing at Exception Level 3 (EL3).
ATF is used as the initial start code on ARMv8-A cores for all K3 platforms. After setting up the initial core state and applying any needed errata fixes it sets up itself as the EL3 monitor handler. After this is installs the secure world software (OP-TEE) and passes execution on to either the Linux kernel or U-Boot in the non-secure world.
Getting the ATF Source Code
The pre-built TF-A binary should be packaged in TI Processor SDK: <path-to-processor-sdk>/board-support/prebuilt-images/<optional-build-machine-name>/bl31.bin. Use this binary since it has been tested with TI Processor SDK.
If it is not possible to use pre-build binary, use the following:
$ git clone https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git
$ git checkout <hash>
Where <hash> is the OPTEE commit shown here: tf-a-release-notes.
Building ATF
$ make CROSS_COMPILE=aarch64-none-linux-gnu- ARCH=aarch64 PLAT=k3 TARGET_BOARD=j784s4 SPD=opteed K3_USART=0x8
Default load locations
+---------------------------+------------+
| ATF image | 0x70000000 |
+---------------------------+------------+
| OP-TEE image | 0x9e800000 |
+---------------------------+------------+
| U-Boot/Linux kernel image | 0x80080000 |
+---------------------------+------------+
| DTB | 0x82000000 |
+---------------------------+------------+