From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752485AbcGAIoN (ORCPT ); Fri, 1 Jul 2016 04:44:13 -0400 Received: from mga02.intel.com ([134.134.136.20]:31500 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751975AbcGAIoE (ORCPT ); Fri, 1 Jul 2016 04:44:04 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.26,556,1459839600"; d="scan'208";a="986950250" Date: Fri, 1 Jul 2016 11:43:23 +0300 From: Jarkko Sakkinen To: apronin@chromium.org Cc: Peter Huewe , Marcel Selhorst , Jason Gunthorpe , Christophe Ricard , tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [RESEND][PATCH] tpm: read burstcount from TPM_STS in one 32-bit transaction Message-ID: <20160701084323.GA15718@intel.com> References: <1467307543-44566-1-git-send-email-apronin@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1467307543-44566-1-git-send-email-apronin@chromium.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 30, 2016 at 10:25:43AM -0700, apronin@chromium.org wrote: > 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 Reviewed-by: Jarkko Sakkinen /Jarkko > --- > > 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 >