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tpm_tis_core: Choose appropriate timeout for reading burstcount

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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.

Cc: stable@vger.kernel.org
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>
This commit is contained in:
Alexander Steffen 2017-02-16 15:33:36 +00:00 committed by Jarkko Sakkinen
parent ddb99e118e
commit 302a6ad7fc
1 changed files with 4 additions and 2 deletions
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6
drivers/char/tpm/tpm_tis_core.c
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@ -160,8 +160,10 @@ static int get_burstcount(struct tpm_chip *chip)
u32 value;
/* wait for burstcount */
/* which timeout value, spec has 2 answers (c & d) */
stop = jiffies + chip->timeout_d;
if (chip->flags & TPM_CHIP_FLAG_TPM2)
stop = jiffies + chip->timeout_a;
else
stop = jiffies + chip->timeout_d;
do {
rc = tpm_tis_read32(priv, TPM_STS(priv->locality), &value);
if (rc < 0)