Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753808AbdC1PaP (ORCPT ); Tue, 28 Mar 2017 11:30:15 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:50642 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753211AbdC1PaN (ORCPT ); Tue, 28 Mar 2017 11:30:13 -0400 From: Enric Balletbo i Serra To: Peter Huewe Cc: Andrew Lunn , tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, wsa@the-dreams.de, Jarkko Sakkinen , Bryan Freed Subject: [PATCH v3] tpm: Apply a sane minimum adapterlimit value for retransmission. Date: Tue, 28 Mar 2017 17:29:38 +0200 Message-Id: <20170328152938.14539-1-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 Content-Length: 4173 Lines: 130 From: Bryan Freed When the I2C Infineon part is attached to an I2C adapter that imposes a size limitation, large requests will fail with -EOPNOTSUPP. Retry them with a sane minimum size without re-issuing the 0x05 command as this appears to occasionally put the TPM in a bad state. Signed-off-by: Bryan Freed [rework the patch to adapt to the feedback received] Signed-off-by: Enric Balletbo i Serra --- This is a reworked version of the original patch based on the suggestion made by Wolfram Sang to simply fall back to a sane minimum when the maximum fails. Changes since v2: - Do not remove faster transfers when chip is SLB9645 (Peter Huewe) - Remember the adapterlimit length once it fails to not generate extra i2c core messages (suggested by Andrew Lunn) Changes since v1: - Check the correct return value (-EOPNOTSUPP instead of -EINVAL) - Fall back len to I2C_SMBUS_BLOCK_MAX if fails. drivers/char/tpm/tpm_i2c_infineon.c | 76 +++++++++++++++++++++++++++---------- 1 file changed, 56 insertions(+), 20 deletions(-) diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c index 62ee44e..fdefcdb 100644 --- a/drivers/char/tpm/tpm_i2c_infineon.c +++ b/drivers/char/tpm/tpm_i2c_infineon.c @@ -70,6 +70,7 @@ struct tpm_inf_dev { u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */ struct tpm_chip *chip; enum i2c_chip_type chip_type; + unsigned int adapterlimit; }; static struct tpm_inf_dev tpm_dev; @@ -111,6 +112,7 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) int rc = 0; int count; + unsigned int msglen = len; /* Lock the adapter for the duration of the whole sequence. */ if (!tpm_dev.client->adapter->algo->master_xfer) @@ -131,27 +133,61 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); } } else { - /* 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 */ - - usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); - } - - if (rc <= 0) - goto out; - - /* After the TPM has successfully received the register address - * it needs some time, thus we're sleeping here again, before - * retrieving the data + /* Expect to send one command message and one data message, but + * support looping over each or both if necessary. */ - for (count = 0; count < MAX_COUNT; count++) { - usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); - rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1); - if (rc > 0) - break; + 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 */ + + usleep_range(SLEEP_DURATION_LOW, + SLEEP_DURATION_HI); + } + + if (rc <= 0) + goto out; + + /* After the TPM has successfully received the register + * address it needs some time, thus we're sleeping here + * again, before retrieving the data + */ + for (count = 0; count < MAX_COUNT; count++) { + if (tpm_dev.adapterlimit) { + msglen = min_t(unsigned int, + tpm_dev.adapterlimit, + len); + msg2.len = msglen; + } + usleep_range(SLEEP_DURATION_LOW, + SLEEP_DURATION_HI); + rc = __i2c_transfer(tpm_dev.client->adapter, + &msg2, 1); + if (rc > 0) { + /* Since len is unsigned, make doubly + * sure we do not underflow it. + */ + if (msglen > len) + len = 0; + else + len -= msglen; + msg2.buf += msglen; + break; + } + /* If the I2C adapter rejected the request (e.g + * when the quirk read_max_len < len) fall back + * to a sane minimum value and try again. + */ + if (rc == -EOPNOTSUPP) + tpm_dev.adapterlimit = + I2C_SMBUS_BLOCK_MAX; + } + + if (rc <= 0) + goto out; } } -- 2.9.3