|
|
|
|
Socionext UniPhier
|
|
|
|
|
==================
|
|
|
|
|
|
|
|
|
|
Socionext UniPhier Armv8-A SoCs use Trusted Firmware-A (TF-A) as the secure
|
|
|
|
|
world firmware, supporting BL2 and BL31.
|
|
|
|
|
|
|
|
|
|
UniPhier SoC family implements its internal boot ROM, which loads 64KB [1]_
|
|
|
|
|
image from a non-volatile storage to the on-chip SRAM, and jumps over to it.
|
|
|
|
|
TF-A provides a special mode, BL2-AT-EL3, which enables BL2 to execute at EL3.
|
|
|
|
|
It is useful for platforms with non-TF-A boot ROM, like UniPhier. Here, a
|
|
|
|
|
problem is BL2 does not fit in the 64KB limit if `Trusted Board Boot`_ (TBB)
|
|
|
|
|
is enabled. To solve this issue, Socionext provides a first stage loader
|
|
|
|
|
called `UniPhier BL`_. This loader runs in the on-chip SRAM, initializes the
|
|
|
|
|
DRAM, expands BL2 there, and hands the control over to it. Therefore, all images
|
|
|
|
|
of TF-A run in DRAM.
|
|
|
|
|
|
|
|
|
|
The UniPhier platform works with/without TBB. See below for the build process
|
|
|
|
|
of each case. The image authentication for the UniPhier platform fully
|
|
|
|
|
complies with the Trusted Board Boot Requirements (TBBR) specification.
|
|
|
|
|
|
|
|
|
|
The UniPhier BL does not implement the authentication functionality, that is,
|
|
|
|
|
it can not verify the BL2 image by itself. Instead, the UniPhier BL assures
|
|
|
|
|
the BL2 validity in a different way; BL2 is GZIP-compressed and appended to
|
|
|
|
|
the UniPhier BL. The concatenation of the UniPhier BL and the compressed BL2
|
|
|
|
|
fits in the 64KB limit. The concatenated image is loaded by the internal boot
|
|
|
|
|
ROM (and verified if the chip fuses are blown).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Boot Flow
|
|
|
|
|
---------
|
|
|
|
|
|
|
|
|
|
1. The Boot ROM
|
|
|
|
|
|
|
|
|
|
This is hard-wired ROM, so never corrupted. It loads the UniPhier BL (with
|
|
|
|
|
compressed-BL2 appended) into the on-chip SRAM. If the SoC fuses are blown,
|
|
|
|
|
the image is verified by the SoC's own method.
|
|
|
|
|
|
|
|
|
|
2. UniPhier BL
|
|
|
|
|
|
|
|
|
|
This runs in the on-chip SRAM. After the minimum SoC initialization and DRAM
|
|
|
|
|
setup, it decompresses the appended BL2 image into the DRAM, then jumps to
|
|
|
|
|
the BL2 entry.
|
|
|
|
|
|
|
|
|
|
3. BL2 (at EL3)
|
|
|
|
|
|
|
|
|
|
This runs in the DRAM. It extracts more images such as BL31, BL33 (optionally
|
|
|
|
|
SCP_BL2, BL32 as well) from Firmware Image Package (FIP). If TBB is enabled,
|
|
|
|
|
they are all authenticated by the standard mechanism of TF-A.
|
|
|
|
|
After loading all the images, it jumps to the BL31 entry.
|
|
|
|
|
|
|
|
|
|
4. BL31, BL32, and BL33
|
|
|
|
|
|
|
|
|
|
They all run in the DRAM. See `Firmware Design`_ for details.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Basic Build
|
|
|
|
|
-----------
|
|
|
|
|
|
|
|
|
|
BL2 must be compressed for the reason above. The UniPhier's platform makefile
|
|
|
|
|
provides a build target ``bl2_gzip`` for this.
|
|
|
|
|
|
|
|
|
|
For a non-secure boot loader (aka BL33), U-Boot is well supported for UniPhier
|
|
|
|
|
SoCs. The U-Boot image (``u-boot.bin``) must be built in advance. For the build
|
|
|
|
|
procedure of U-Boot, refer to the document in the `U-Boot`_ project.
|
|
|
|
|
|
|
|
|
|
To build minimum functionality for UniPhier (without TBB)::
|
|
|
|
|
|
|
|
|
|
make CROSS_COMPILE=<gcc-prefix> PLAT=uniphier BL33=<path-to-BL33> bl2_gzip fip
|
|
|
|
|
|
|
|
|
|
Output images:
|
|
|
|
|
|
|
|
|
|
- ``bl2.bin.gz``
|
|
|
|
|
- ``fip.bin``
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Optional features
|
|
|
|
|
-----------------
|
|
|
|
|
|
|
|
|
|
- Trusted Board Boot
|
|
|
|
|
|
|
|
|
|
`mbed TLS`_ is needed as the cryptographic and image parser modules.
|
|
|
|
|
Refer to the `User Guide`_ for the appropriate version of mbed TLS.
|
|
|
|
|
|
|
|
|
|
To enable TBB, add the following options to the build command::
|
|
|
|
|
|
|
|
|
|
TRUSTED_BOARD_BOOT=1 GENERATE_COT=1 MBEDTLS_DIR=<path-to-mbedtls>
|
|
|
|
|
|
|
|
|
|
- System Control Processor (SCP)
|
|
|
|
|
|
|
|
|
|
If desired, FIP can include an SCP BL2 image. If BL2 finds an SCP BL2 image
|
|
|
|
|
in FIP, BL2 loads it into DRAM and kicks the SCP. Most of UniPhier boards
|
|
|
|
|
still work without SCP, but SCP provides better power management support.
|
|
|
|
|
|
|
|
|
|
To include SCP BL2, add the following option to the build command::
|
|
|
|
|
|
|
|
|
|
SCP_BL2=<path-to-SCP>
|
|
|
|
|
|
|
|
|
|
- BL32 (Secure Payload)
|
|
|
|
|
|
|
|
|
|
To enable BL32, add the following options to the build command::
|
|
|
|
|
|
|
|
|
|
SPD=<spd> BL32=<path-to-BL32>
|
|
|
|
|
|
|
|
|
|
If you use TSP for BL32, ``BL32=<path-to-BL32>`` is not required. Just add the
|
|
|
|
|
following::
|
|
|
|
|
|
|
|
|
|
SPD=tspd
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
.. [1] Some SoCs can load 80KB, but the software implementation must be aligned
|
|
|
|
|
to the lowest common denominator.
|
|
|
|
|
.. _Trusted Board Boot: ../trusted-board-boot.rst
|
|
|
|
|
.. _UniPhier BL: https://github.com/uniphier/uniphier-bl
|
|
|
|
|
.. _Firmware Design: ../firmware-design.rst
|
|
|
|
|
.. _U-Boot: https://www.denx.de/wiki/U-Boot
|
|
|
|
|
.. _mbed TLS: https://tls.mbed.org/
|
|
|
|
|
.. _User Guide: ../user-guide.rst
|
