This series is the u-boot fix to a problem we encountered when enabling
OPTEE/TrustZone on the WaRP7. The symptom is once TrustZone is activated
the first page of CAAM registers becomes read-only, read-zero from the
perspective of Linux and other non TrustZone contexts.
Offlining the problem with Peng Fan[1] we eventually came to realise the
problem could be worked around by
1. Making Linux skip RNG initialisation - a set of patches should be
hitting LKML to do just that.
2. Initialising the RNG either from u-boot or OPTEE. In this case u-boot is
the right place to-do that because there's upstream code in u-boot that
just works. Patch #2 does that for the WaRP7.
3. Ensuring the job-ring registers are assigned to the non TrustZone mode.
On the i.MX7 after the BootROM runs the job-ring registers are assigned
to TrustZone. Patch #1 does that for all CAAM hardware.
On point #3 this ordinarily isn't a problem because unless TrustZone is
activated the restrictions on the job-ring registers don't kick in, its
only after enabling TrustZone that Linux will loose access to the job-ring
registers.
Finally should OPTEE or another TEE want to do things with the job-ring
registers it will have sufficient privilege to assign whichever job-ring
registers it wants to OPTEE/TEE but will naturally then have to arbitrate
with Linux to inform the Kernel CAAM driver which job-ring registers it can
and cannot access.
That arbitration process is for a future putative OPTEE/TEE CAAM driver to
solve and is out of scope of this patchset.
[1] Thanks for all of your help BTW - Peng, there's no way this would be
working without you giving direction on how.
Bryan O'Donoghue (2):
drivers/crypto/fsl: assign job-rings to non-TrustZone
warp7 : run sec_init for CAAM RNG
board/warp7/warp7.c | 6 +++++-
drivers/crypto/fsl/jr.c | 9 +++++++++
drivers/crypto/fsl/jr.h | 1 +
3 files changed, 15 insertions(+), 1 deletion(-)
--
2.7.4
_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
https://lists.denx.de/listinfo/u-boot
