tpm_crb: Add support for CRB devices based on Pluton
Pluton is an integrated security processor present in some recent Ryzen parts. If it's enabled, it presents two devices - an MSFT0101 ACPI device that's broadly an implementation of a Command Response Buffer TPM2, and an MSFT0200 ACPI device whose functionality I haven't examined in detail yet. This patch only attempts to add support for the TPM device. There's a few things that need to be handled here. The first is that the TPM2 ACPI table uses a previously undefined start method identifier. The table format appears to include 16 bytes of startup data, which corresponds to one 64-bit address for a start message and one 64-bit address for a completion response. The second is that the ACPI tables on the Thinkpad Z13 I'm testing this on don't define any memory windows in _CRS (or, more accurately, there are two empty memory windows). This check doesn't seem strictly necessary, so I've skipped that. Finally, it seems like chip needs to be explicitly asked to transition into ready status on every command. Failing to do this means that if two commands are sent in succession without an idle/ready transition in between, everything will appear to work fine but the response is simply the original command. I'm working without any docs here, so I'm not sure if this is actually the required behaviour or if I'm missing something somewhere else, but doing this results in the chip working reliably. Reviewed-by:Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by:
Matthew Garrett <mjg59@srcf.ucam.org> Signed-off-by:
Jarkko Sakkinen <jarkko@kernel.org>
parent
0f5d4a0b
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