From ffbce80bcb9d378c86e0fe47be6572b2fc1c5baa Mon Sep 17 00:00:00 2001 From: Andrey Pronin Date: Thu, 30 Jun 2016 10:25:43 -0700 Subject: [PATCH] tpm: read burstcount from TPM_STS in one 32-bit transaction commit 9754d45e997000ad4021bc4606cc266bb38d876f upstream. 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 Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen [bwh: Backported to 3.2: - Use raw ioread32() instead of tpm_tis_read32() - Adjust filename, context] Signed-off-by: Ben Hutchings --- drivers/char/tpm/tpm_tis.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c index f8e94fe197b9..0c4885dd43b8 100644 --- a/drivers/char/tpm/tpm_tis.c +++ b/drivers/char/tpm/tpm_tis.c @@ -176,16 +176,15 @@ static int get_burstcount(struct tpm_chip *chip) { unsigned long stop; int burstcnt; + u32 value; /* wait for burstcount */ /* which timeout value, spec has 2 answers (c & d) */ stop = jiffies + chip->vendor.timeout_d; do { - burstcnt = ioread8(chip->vendor.iobase + - TPM_STS(chip->vendor.locality) + 1); - burstcnt += ioread8(chip->vendor.iobase + - TPM_STS(chip->vendor.locality) + - 2) << 8; + value = ioread32(chip->vendor.iobase + + TPM_STS(chip->vendor.locality)); + burstcnt = (value >> 8) & 0xFFFF; if (burstcnt) return burstcnt; msleep(TPM_TIMEOUT); -- 2.39.2