Commit e8bd417a authored by Sasha Levin's avatar Sasha Levin Committed by Jarkko Sakkinen
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tpm/tpm_ftpm_tee: Document fTPM TEE driver 



Documentation briefly the new fTPM driver running inside TEE.

Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Reviewed-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
parent 09e57483

Documentation/security/tpm/index.rst

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   tpm_vtpm_proxy

   xen-tpmfront

   tpm_ftpm_tee

Documentation/security/tpm/tpm_ftpm_tee.rst

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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.