tFrom 1dc5533382b9951c70b1a38f02065b41453b175a Mon Sep 17 00:00:00 2001

Stuart Yoder
2025-03-12T21:58:37Z

Firmware Framework for Arm A-profile (FF-A) is a messaging framework
for Arm-based systems, and in the context of the TPM CRB driver is used
to signal 'start' to a CRB-based TPM service which is hosted in an
FF-A secure partition running in TrustZone.

These patches add support for the CRB FF-A start method defined
in the TCG ACPI specification v1.4 and the FF-A ABI defined
in the Arm TPM Service CRB over FF-A (DEN0138) specification:
https://developer.arm.com/documentation/den0138/latest/

The first patch adds an FF-A driver to handle the FF-A messaging when
communicating with a CRB-based TPM secure partition built on FF-A.
The driver is probed when the TPM secure partition is discovered by
the Linux FF-A infrastructure.

The second patch consolidates the check for idle support in the CRB
driver to one place.

The third patch defines the new ACPI start method enumeration for
CRB over FF-A.

The fourth patch adds support for the FF-A ACPI start method to
the TPM crb driver.

The fifth patch adds documentation explaining how the CRB driver
and FF-A relate.

Version 8
-all changes made to patch 1:
-fixed link error when tpm_crb was built-in and tpm_ffa_crb
was built as module by changing IS_ENABLED() to IS_REACHABLE()
in tpm_ffa_crb.h
-cleaned up Kconfig definition for tpm_ffa_crb
-added Jarkko's Reviewed-by tag
-added ffa_tpm: to subject

Version 7
-added the tpm_ffa_crb documentation to index.rst

Version 6
-in tpm_crb removed unnecessary brackets from if statement and
fixed comment style
-noticed and fixed bug in patch 2, polarity of return value
from tpm_crb_has_idle() was wrong and wasn't caught in past
testing
-added Reviewed-by tag to patches 2 and 5

Version 5
-tpm_ffa_crb patch: removed module version
-tpm_ffa_crb patch: fixed module description
-tpm_ffa_crb patch: updated comment on mutex declaration
-reworded commit message for patch 2 as per Jarkko's
suggestion
-added Acked tag by Sudeep to patch 1 for FF-A changes
-added Reviewed-by tag to patches 3 and 4

Version 4
-fix warning from kernel test robot in patch 1
-fix warnings from checkpatch.pl --strict
-clean up unnecessary parenthesis usage
-update variable declaration to be reverse tree order
-document exported functions in tpm_crb_ffa driver
-remove unnecessary author and maintainer info in tpm_crb_ffa driver
-fix declaration of variables to be in reverse tree order

Version 3
-changed prefixes used throughout patch series to tpm_crb_ffa*

Version 2
-updates to cover letter to define FF-A
-added new patch with documentation
-created pull request in ACPIA and added link to the patch
updating actbl3.h
-added tpm_ prefix to the FF-A CRB driver

Stuart Yoder (5):
tpm_crb: ffa_tpm: implement driver compliant to CRB over FF-A
tpm_crb: clean-up and refactor check for idle support
ACPICA: add start method for Arm FF-A
tpm_crb: add support for the Arm FF-A start method
Documentation: tpm: add documentation for the CRB FF-A interface

Documentation/security/tpm/index.rst | 1 +
Documentation/security/tpm/tpm_ffa_crb.rst | 65 ++++
drivers/char/tpm/Kconfig | 9 +
drivers/char/tpm/Makefile | 1 +
drivers/char/tpm/tpm_crb.c | 105 +++++--
drivers/char/tpm/tpm_crb_ffa.c | 348 +++++++++++++++++++++
drivers/char/tpm/tpm_crb_ffa.h | 25 ++
include/acpi/actbl3.h | 1 +
8 files changed, 536 insertions(+), 19 deletions(-)
create mode 100644 Documentation/security/tpm/tpm_ffa_crb.rst
create mode 100644 drivers/char/tpm/tpm_crb_ffa.c
create mode 100644 drivers/char/tpm/tpm_crb_ffa.h

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