| ============================================= |
| 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. |
