diff options
| author | Andrey Pronin <apronin@chromium.org> | 2016-06-30 10:25:43 -0700 |
|---|---|---|
| committer | Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> | 2016-07-19 17:43:38 +0300 |
| commit | 9754d45e997000ad4021bc4606cc266bb38d876f (patch) | |
| tree | 1d4cd24830105e0ea9c14bc6bb6bc11ee23995c3 /drivers/char | |
| parent | 1b0612b04090e416828c0dd5ed197b0913d834a0 (diff) | |
tpm: read burstcount from TPM_STS in one 32-bit transaction
Some chips incorrectly support partial reads from TPM_STS register
at non-zero offsets. Read the entire 32-bits register instead of
making two 8-bit reads to support such devices and reduce the number
of bus transactions when obtaining the burstcount from TPM_STS.
Fixes: 27084efee0c3 ("tpm: driver for next generation TPM chips")
Signed-off-by: Andrey Pronin <apronin@chromium.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/tpm/tpm_tis_core.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index ace95b39566f..fb8c3de55746 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -157,22 +157,17 @@ static int get_burstcount(struct tpm_chip *chip) struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); unsigned long stop; int burstcnt, rc; - u8 value; + u32 value; /* wait for burstcount */ /* which timeout value, spec has 2 answers (c & d) */ stop = jiffies + chip->timeout_d; do { - rc = tpm_tis_read8(priv, TPM_STS(priv->locality) + 1, &value); + rc = tpm_tis_read32(priv, TPM_STS(priv->locality), &value); if (rc < 0) return rc; - burstcnt = value; - rc = tpm_tis_read8(priv, TPM_STS(priv->locality) + 2, &value); - if (rc < 0) - return rc; - - burstcnt += value << 8; + burstcnt = (value >> 8) & 0xFFFF; if (burstcnt) return burstcnt; msleep(TPM_TIMEOUT); |