tpm_tis_core: Choose appropriate timeout for reading burstcount
authorAlexander Steffen <Alexander.Steffen@infineon.com>
Thu, 16 Feb 2017 15:33:36 +0000 (15:33 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 25 May 2017 13:44:30 +0000 (15:44 +0200)
commit5c1bd0cb49929e84bfafc2c442dfa9b54e26a4a4
tree3fdacf90815a7cff2887d817acd3403bf0fd024d
parent3888f62943bbc77496dc919080296c3a954b56a9
tpm_tis_core: Choose appropriate timeout for reading burstcount

commit 302a6ad7fc77146191126a1f3e2c5d724fd72416 upstream.

TIS v1.3 for TPM 1.2 and PTP for TPM 2.0 disagree about which timeout
value applies to reading a valid burstcount. It is TIMEOUT_D according to
TIS, but TIMEOUT_A according to PTP, so choose the appropriate value
depending on whether we deal with a TPM 1.2 or a TPM 2.0.

This is important since according to the PTP TIMEOUT_D is much smaller
than TIMEOUT_A. So the previous implementation could run into timeouts
with a TPM 2.0, even though the TPM was behaving perfectly fine.

During tpm2_probe TIMEOUT_D will be used even with a TPM 2.0, because
TPM_CHIP_FLAG_TPM2 is not yet set. This is fine, since the timeout values
will only be changed afterwards by tpm_get_timeouts. Until then
TIS_TIMEOUT_D_MAX applies, which is large enough.

Fixes: aec04cbdf723 ("tpm: TPM 2.0 FIFO Interface")
Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Signed-off-by: Peter Huewe <peter.huewe@infineon.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/char/tpm/tpm_tis_core.c