tpm_ftpm_tee.rst

 1=============================================
 2Firmware TPM Driver
 3=============================================
 4
 5This document describes the firmware Trusted Platform Module (fTPM)
 6device driver.
 7
 8Introduction
 9============
10
11This driver is a shim for firmware implemented in ARM's TrustZone
12environment. The driver allows programs to interact with the TPM in the same
13way they would interact with a hardware TPM.
14
15Design
16======
17
18The driver acts as a thin layer that passes commands to and from a TPM
19implemented in firmware. The driver itself doesn't contain much logic and is
20used more like a dumb pipe between firmware and kernel/userspace.
21
22The firmware itself is based on the following paper:
23https://www.microsoft.com/en-us/research/wp-content/uploads/2017/06/ftpm1.pdf
24
25When the driver is loaded it will expose ``/dev/tpmX`` character devices to
26userspace which will enable userspace to communicate with the firmware TPM
27through this device.