[PATCH v2 0/4] tpm: Cache ACPI TPM2 start method and gate tpm_crb_ffa probe

[Siddharth Chintamaneni <sidchintamaneni@gmail.com>]

This series caches the ACPI TPM2 start method in tpm_init() and uses
the cached tpm2_acpi_start_method value across tpm_crb_ffa, tpm_tis,
and tpm_crb.

Patch 1 caches the ACPI TPM2 start method once in tpm_init() into
tpm2_acpi_start_method (defaulting to ACPI_TPM2_NOT_ALLOWED when
absent or invalid).
Patch 2 checks tpm2_acpi_start_method in tpm_crb_ffa_probe() and
returns -ENODEV unless ACPI advertises ACPI_TPM2_CRB_WITH_ARM_FFA,
skipping FF-A probing on non-FF-A platforms while keeping modular
tpm_crb/tpm_crb_ffa loading intact.
Patches 3 and 4 update tpm_tis and tpm_crb to use the cached
tpm2_acpi_start_method value during probe.

Changes in v2:
- Expand into a 4-patch series caching tpm2_acpi_start_method in
  tpm_init() and converting tpm_crb_ffa, tpm_tis, and tpm_crb to use
  it (Jarkko Sakkinen).
- Move the tpm_crb_ffa start_method check from module_init into
  tpm_crb_ffa_probe() so tpm_crb.ko and tpm_crb_ffa.ko still load
  cleanly on non-FF-A systems when built as modules.

v1: https://lore.kernel.org/linux-integrity/20261112233807.70664-1-sidchintamaneni@gmail.com/

Jarkko Sakkinen (1):
  tpm: Cache TPM2 start method

Siddharth Chintamaneni (3):
  tpm: tpm_crb_ffa: Only probe when ACPI TPM2 uses FF-A
  tpm: tpm_tis: Use cached tpm2_acpi_start_method
  tpm: tpm_crb: Use cached tpm2_acpi_start_method

 drivers/char/tpm/tpm-interface.c | 21 +++++++++++++++++++++
 drivers/char/tpm/tpm.h           |  1 +
 drivers/char/tpm/tpm_crb.c       | 19 ++++++++++++-------
 drivers/char/tpm/tpm_crb_ffa.c   |  5 +++++
 drivers/char/tpm/tpm_tis.c       | 18 +++++++-----------
 5 files changed, 46 insertions(+), 18 deletions(-)


base-commit: 912c3bad2eb993eb3e83c2689cd4e17361ef087f
-- 
2.45.4