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1=============================================2Firmware TPM Driver3=============================================4 5This document describes the firmware Trusted Platform Module (fTPM)6device driver.7 8Introduction9============10 11This driver is a shim for firmware implemented in ARM's TrustZone12environment. The driver allows programs to interact with the TPM in the same13way they would interact with a hardware TPM.14 15Design16======17 18The driver acts as a thin layer that passes commands to and from a TPM19implemented in firmware. The driver itself doesn't contain much logic and is20used 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.pdf24 25When the driver is loaded it will expose ``/dev/tpmX`` character devices to26userspace which will enable userspace to communicate with the firmware TPM27through this device.28