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repo: https://github.com/T-head-Semi/linux commit: b1313fe517ca3703119dcc99ef3bbf75ab42bcfb Change-Id: I6cbb35294024ea3a66140e311f4bb705fd7fd626
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=============================================
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Firmware TPM Driver
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=============================================
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This document describes the firmware Trusted Platform Module (fTPM)
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device driver.
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Introduction
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============
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This driver is a shim for firmware implemented in ARM's TrustZone
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environment. The driver allows programs to interact with the TPM in the same
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way they would interact with a hardware TPM.
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Design
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======
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The driver acts as a thin layer that passes commands to and from a TPM
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implemented in firmware. The driver itself doesn't contain much logic and is
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used more like a dumb pipe between firmware and kernel/userspace.
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The firmware itself is based on the following paper:
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https://www.microsoft.com/en-us/research/wp-content/uploads/2017/06/ftpm1.pdf
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When the driver is loaded it will expose ``/dev/tpmX`` character devices to
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userspace which will enable userspace to communicate with the firmware TPM
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through this device.
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