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System Firmware (SYSFW) and Configuration Image Generator TI K3 Family SoCs

Overview

This tool is intended to be a simple solution to allow users to create an image tree blob (a.k.a. FIT image) comprising a signed System Firmware image as well as the binary configuration artifacts needed to bring up SYSFW as part of the U-Boot SPL startup. Note that the final SYSFW configuration itself is expected to be performed by the end user by directly modifying different C source files included into this project as needed for an application and board-specific use case. The domain-specific configuration artifacts to be tailored are:

  • board-cfg.c contains the general board configuration
  • pm-cfg.c contains the power management / clock related configuration
  • rm-cfg.c contains the resource management / allocation related configuration
  • sec-cfg.c contains the security configuration

These files exist under {srcroot}/soc/{soc}/{configuration}/ folders, Where: * srcroot - Is the root folder of source code * soc - Is one of the supported SoCs. Example: am65x * configuration - This is one of the supported configurations for various resource division desired. Example: evm

NOTE: The definitions for the same are available under {srcroot}/include/soc/{soc} folder

The build process consumes a raw (unsigned) SYSFW binary image as released by the SYSFW development team and signs it by adding an X.509 certificate using a random key.

The signed SYSFW image as well as the configuration artifacts will then all get build into an ITB blob (FIT image) named sysfw-{soc}-{configuration}.itb ready for consumption by U-Boot SPL.

Building SYSFW Image and Configuration Data

First, ensure you have a current mkimage tool and ARMv7 cross toolchain installed. The SYSFW configuration generator was developed and tested using...

$ mkimage -V
mkimage version 2013.10

$ arm-linux-gnueabihf-gcc --version
arm-linux-gnueabihf-gcc (Linaro GCC 7.2-2017.11) 7.2.1 20171011
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Also make sure to have a proper unsigned SYSFW image populated at the root of this project, otherwise a version specified in the Makefile via Git commit hash will be downloaded from the TI SYSFW release URL (see download location below).

The default SYSFW image consumed by the build process is called ti-sci-firmware-{soc}-gp.bin however this may be overwritten and customized using the SYSFW_PATH make variable. The build process will fail if the image can't be downloaded to {srcroot} or no such file has gotten populated into that folder by other means.

Further note by default the SYSFW image for use with general purpose (GP) devices (as opposed to high security devices) is signed with the TI degenerate key to optimize boot time (less processing time needed by ROM) but can also be signed with a random cryptoraphic key or another user-provided key. This signing behavior is controlled through the KEY make variable. Not explicitly setting KEY will result in the use of the TI degenerate key. To use a custom key populate the KEY variable to point to the key to get used. By clearing the default key setting by passing in KEY="" a random key will get generated and used during the build process.

In order to download the SYSFW release image (if needed) and build the final sysfw-{soc}-{configuration}.itb for consumption by U-Boot SPL simply by perform a make.

$ make

Note that in case of filesystem-based boot such as booting from SD card sysfw-{soc}-{configuration}.itb needs to be manually renamed to syswfw.itb before populating it to the (SD card) boot media as this is the file name U-Boot SPL will be trying to load early during the boot process. This renaming step is not necessary for RAW boot modes such as eMMC (in RAW mode), (x)SPI, and others.

$ mv sysfw-{soc}-{configuration}.itb syswfw.itb

To extract and show the release version of the SYSFW image being used...

$ make sysfw_version
SYSFW Version: v2018.08a (Curious Crow)

To extract the 'creator' information from the final generated sysfw-{soc}-{configuration}.itb image tree blob...

$ fdtget sysfw-am65x-evm.itb / creator
SIG am65x/evm-ti2019.01-14-g47b8d

The workspace can be cleaned up by doing...

$ make clean

To also remove the SYSFW image do this...

$ make mrproper

The following flags further modify the build steps: * SOC - Choose one of the supported SoCs (see folder name under {srcroot}/soc). Defaults to am65x * CONFIG - Choose of various configurations supported (see folder name under {srcroot}/soc/{soc}). Defaults to evm * O - Choose where the intermediate build files need to be located * BIN_DIR - Choose where the final output sysfw-{soc}-{configuration}.itb needs to be generated to. * KEY - Choose key to use for the signing system firmware image * ENABLE_TRACE=1 - Choose to enable sysfw traces while booting.

Building SYSFW Image for High-Security(HS) devices

The process for building and image suitable for use with HS devices is similar to the above process with the following differences:

The make commands should be appended with HS=1,

$ make HS=1

The environment variable TI_SECURE_DEV_PKG should be defined to point to the TI Secure Development Tools package.

There are two images downloaded and consumed by the build process.

* ti-sci-firmware-{soc}-hs-enc.bin: Encrypted HS SYSFW image
* ti-sci-firmware-{soc}-hs-cert.bin: Inner-certificate for HS SYSFW image

The inner-certificate is signed by the key provided by the TI_SECURE_DEV_PKG path producing an outer-certificate. These images are then appended to produce the final sysfw-{soc}-{configuration}.bin which is bundled with the configuration data exactly as the non-HS version above.

Important Notes

There is a strong dependency of the used System Firmware release version and how the board configuration data needs to be structured and/or filled in. Using config data that is not compatible with a given SYSFW release may lead to failures during loading of the data by U-Boot SPL, or failures later downstream in U-Boot or during Linux boot.

It is strongly recommended to review System Firmware release documentation in great detail(!) to make sure suitable board configuration is provided. Common pitfalls preventing proper system operation include but are not limited to using an unsuitable or invalid resource management configuration.

References