tpm/tpm_ftpm_tee: Document fTPM TEE driver

Documentation briefly the new fTPM driver running inside TEE.

Signed-off-by: Sasha Levin <sashal@kernel.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
This commit is contained in:
Sasha Levin 2019-07-05 16:47:46 -04:00 committed by Jarkko Sakkinen
parent 09e574831b
commit e8bd417aab
2 changed files with 28 additions and 0 deletions

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@ -6,3 +6,4 @@ Trusted Platform Module documentation
tpm_vtpm_proxy
xen-tpmfront
tpm_ftpm_tee

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=============================================
Firmware TPM Driver
=============================================
This document describes the firmware Trusted Platform Module (fTPM)
device driver.
Introduction
============
This driver is a shim for firmware implemented in ARM's TrustZone
environment. The driver allows programs to interact with the TPM in the same
way they would interact with a hardware TPM.
Design
======
The driver acts as a thin layer that passes commands to and from a TPM
implemented in firmware. The driver itself doesn't contain much logic and is
used more like a dumb pipe between firmware and kernel/userspace.
The firmware itself is based on the following paper:
https://www.microsoft.com/en-us/research/wp-content/uploads/2017/06/ftpm1.pdf
When the driver is loaded it will expose ``/dev/tpmX`` character devices to
userspace which will enable userspace to communicate with the firmware TPM
through this device.