[PATCH v3 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) and logs it when a TPM2 ACPI table is present.
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 directly.

Changes in v3:
- Log tpm2_acpi_start_method in tpm_init() after acpi_put_table() and
  use a single-line acpi_get_table() call with typeof(tbl->header)
  cast (Jarkko Sakkinen).
- Remove check_acpi_tpm2() in tpm_tis and open-code the check in
  tpm_tis_init(), dropping dev_err() and returning -ENODEV (Jarkko
  Sakkinen).
- Remove priv->sm and local sm in tpm_crb, use tpm2_acpi_start_method
  throughout, drop the probe dev_err() messages, and return -ENODEV
  (Jarkko Sakkinen).

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.

v2: https://lore.kernel.org/linux-integrity/20261114193434.117714-1-sidchintamaneni@gmail.com/
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       | 82 +++++++++++++++-----------------
 drivers/char/tpm/tpm_crb_ffa.c   |  5 ++
 drivers/char/tpm/tpm_tis.c       | 45 +++---------------
 5 files changed, 71 insertions(+), 83 deletions(-)


base-commit: 7e52fc165aa50e70e8df3c879d04fc0ff1673d4a
-- 
2.45.4