tpm: OP-TEE transport core for discrete and firmware TPMs

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/[email protected]/
v2: https://lore.kernel.org/linux-integrity/[email protected]/
v3: https://lore.kernel.org/linux-integrity/[email protected]/

Changes since v3:
- rebased onto the tpmdd tree, which already carries the treewide devm_kmalloc_obj() conversion; the series now applies cleanly without the merge fixups that were needed when v3 was picked up.
- tpm_optee: allocate the private data with devm_kzalloc_obj() instead of devm_kzalloc() with an explicit sizeof(), matching the type-based convention now used across the tree (and already used by the converted tpm_ftpm_tee front-end). No functional change.

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   | 294 ++----------------------------
 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(+), 311 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: c3d9e7297e8d1934c8f2aaa0b9d82018ab15376e

2.55.0