From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753350AbdBUOpR (ORCPT ); Tue, 21 Feb 2017 09:45:17 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:49272 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752740AbdBUOpL (ORCPT ); Tue, 21 Feb 2017 09:45:11 -0500 From: Enric Balletbo i Serra To: Peter Huewe , Marcel Selhorst Cc: apronin@google.com, tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Bryan Freed Subject: [PATCH 1/2] tpm: Apply an adapterlimit for retransmission. Date: Tue, 21 Feb 2017 15:44:59 +0100 Message-Id: <20170221144500.502-1-enric.balletbo@collabora.com> X-Mailer: git-send-email 2.9.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bryan Freed When the I2C Infineon part is attached to an I2C adapter that imposes a size limitation, large requests will fail -EINVAL. Retry them with size backoff without re-issuing the 0x05 command as this appears to occasionally put the TPM in a bad state. Signed-off-by: Bryan Freed Signed-off-by: Enric Balletbo i Serra --- drivers/char/tpm/tpm_i2c_infineon.c | 44 ++++++++++++++++++++++--------------- 1 file changed, 26 insertions(+), 18 deletions(-) diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c index 62ee44e..f04c6b7 100644 --- a/drivers/char/tpm/tpm_i2c_infineon.c +++ b/drivers/char/tpm/tpm_i2c_infineon.c @@ -111,35 +111,24 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) int rc = 0; int count; + int adapterlimit = len; /* Lock the adapter for the duration of the whole sequence. */ if (!tpm_dev.client->adapter->algo->master_xfer) return -EOPNOTSUPP; i2c_lock_adapter(tpm_dev.client->adapter); - if (tpm_dev.chip_type == SLB9645) { - /* use a combined read for newer chips - * unfortunately the smbus functions are not suitable due to - * the 32 byte limit of the smbus. - * retries should usually not be needed, but are kept just to - * be on the safe side. - */ - for (count = 0; count < MAX_COUNT; count++) { - rc = __i2c_transfer(tpm_dev.client->adapter, msgs, 2); - if (rc > 0) - break; /* break here to skip sleep */ - usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); - } - } else { + /* Expect to send one command message and one data message, but + * support looping over each or both if necessary. + */ + while (len > 0) { /* slb9635 protocol should work in all cases */ for (count = 0; count < MAX_COUNT; count++) { rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1); if (rc > 0) - break; /* break here to skip sleep */ - + break; usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); } - if (rc <= 0) goto out; @@ -149,10 +138,29 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) */ for (count = 0; count < MAX_COUNT; count++) { usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); + msg2.len = min(adapterlimit, len); rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1); - if (rc > 0) + if (rc > 0) { + /* Since len is unsigned, make doubly sure we + * do not underflow it. + */ + if (msg2.len > len) + len = 0; + else + len -= msg2.len; + msg2.buf += msg2.len; break; + } + /* If the I2C adapter rejected the request, + * try a smaller chunk. + */ + if (rc == -EINVAL) { + adapterlimit = (adapterlimit + 1) / 2; + adapterlimit = max(adapterlimit, 32); + } } + if (rc <= 0) + goto out; } out: -- 2.9.3