From mboxrd@z Thu Jan 1 00:00:00 1970 From: apronin-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org Subject: [RESEND][PATCH] tpm: read burstcount from TPM_STS in one 32-bit transaction Date: Thu, 30 Jun 2016 10:25:43 -0700 Message-ID: <1467307543-44566-1-git-send-email-apronin@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Jarkko Sakkinen Cc: Christophe Ricard , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net From: Andrey Pronin 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. Signed-off-by: Andrey Pronin --- No changes. Re-sending to tpmdd-devel member-only list after subscribing. drivers/char/tpm/tpm_tis_core.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 03a06b3..8110b52 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); -- 2.6.6 ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape