[PATCH v3 0/2] tpm: OP-TEE transport core for discrete and firmware TPMs

[Jorge Ramirez-Ortiz <jorge.ramirez@oss.qualcomm.com>]

This adds a driver for a discrete TPM that OP-TEE owns and the normal
world cannot reach directly, and factors the shared OP-TEE TEE transport
into a small core so the existing fTPM driver uses it too:

  - a transport core shared by the OP-TEE TPM front-ends;
  - a new discrete TPM front-end;
  - the fTPM driver converted onto the core, keeping its name, its
    platform/OF binding and its shutdown path.

Patch 1 is the feature; patch 2 is the fTPM conversion that justifies the
core. Both front-ends were exercised on the Qualcomm Lemans EVK over the
shared core: the discrete ST33 TPM (patch 1) and the MS-TPM-20 firmware
TPM TA (patch 2), each presenting a working /dev/tpm0 (tpm2_getrandom,
PCR read). The fTPM TA is the same MS-TPM-20 reference the existing
tpm_ftpm_tee platforms use.

This is the normal-world half. The secure-world OP-TEE support it binds
to -- the in-core TPM2 SPI (TIS) driver and the mediator pseudo TA that
relays commands to it -- is under review separately:

  OP-TEE support: https://github.com/OP-TEE/optee_os/pull/8155
  locality 4:     https://github.com/OP-TEE/optee_os/issues/8160
                  (design follow-up: the secure world policing
                  normal-world locality access to the shared chip)

Build and test it on the Qualcomm Lemans EVK (a discrete ST33 TPM on
SPI, owned by OP-TEE):

  https://qualcomm-linux.github.io/qcom-buildroot/lemans/quick-start.html

v1: https://lore.kernel.org/linux-integrity/20261026163259.1900439-1-jorge.ramirez@oss.qualcomm.com/
v2: https://lore.kernel.org/linux-integrity/20261110141923.3100770-1-jorge.ramirez@oss.qualcomm.com/

Changes since v2:
 - tpm_optee_dtpm: give the discrete-TPM front-end a .shutdown callback so
   it releases its TEE session and dynamic shared memory on shutdown/kexec,
   as the fTPM front-end already did; without it the session and the
   normal-world pages stayed registered in OP-TEE across a kexec, which can
   stop the next kernel opening a session to the chip.
 - move the shared tpm_optee_shutdown() helper into the core patch so that
   patch builds on its own; the dTPM front-end no longer forward-references
   a symbol that was added in patch 2.

Changes since v1:
 - split the shared TEE transport into a core; the discrete chip is now a
   thin front-end, the tpm_tis_core-style solution that was asked for.
 - convert the fTPM driver onto the same core instead of duplicating it.
 - use an optee-prefixed name for the new modules; the fTPM driver keeps
   its name, no module rename.
 - rewrite the commit message with a plain description of the components
   and the rationale for a separate front-end.
 - drop the explicit zeroing in favour of initialisers, and reword the
   module description.

Jorge Ramirez-Ortiz (2):
  tpm: add OP-TEE transport core and a discrete TPM driver
  tpm_ftpm_tee: use the tpm_optee transport core

 MAINTAINERS                       |   8 +
 drivers/char/tpm/Kconfig          |  28 +++
 drivers/char/tpm/Makefile         |   2 +
 drivers/char/tpm/tpm_ftpm_tee.c   | 295 ++----------------------------
 drivers/char/tpm/tpm_ftpm_tee.h   |  35 ----
 drivers/char/tpm/tpm_optee.c      | 253 +++++++++++++++++++++++++
 drivers/char/tpm/tpm_optee.h      |  32 ++++
 drivers/char/tpm/tpm_optee_dtpm.c |  73 ++++++++
 8 files changed, 414 insertions(+), 312 deletions(-)
 delete mode 100644 drivers/char/tpm/tpm_ftpm_tee.h
 create mode 100644 drivers/char/tpm/tpm_optee.c
 create mode 100644 drivers/char/tpm/tpm_optee.h
 create mode 100644 drivers/char/tpm/tpm_optee_dtpm.c


base-commit: c03c1a14507dfaf8b856c2608f9ac216021fc222
-- 
2.55.0