Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752739AbdCAPgg (ORCPT ); Wed, 1 Mar 2017 10:36:36 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:44225 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752001AbdCAPgf (ORCPT ); Wed, 1 Mar 2017 10:36:35 -0500 From: Enric Balletbo i Serra To: Peter Huewe Cc: Andrew Lunn , wsa@the-dreams.de, tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Bryan Freed Subject: [PATCH v2] tpm: Apply a sane minimum adapterlimit value for retransmission. Date: Wed, 1 Mar 2017 16:36:17 +0100 Message-Id: <20170301153617.10106-1-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: 3389 Lines: 106 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 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 | 45 +++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 19 deletions(-) diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c index 62ee44e..88bf947 100644 --- a/drivers/char/tpm/tpm_i2c_infineon.c +++ b/drivers/char/tpm/tpm_i2c_infineon.c @@ -107,39 +107,27 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) .len = len, .buf = buffer }; - struct i2c_msg msgs[] = {msg1, msg2}; int rc = 0; int count; + unsigned 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; @@ -148,11 +136,30 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) * retrieving the data */ for (count = 0; count < MAX_COUNT; count++) { + unsigned int msglen = msg2.len = + min_t(unsigned int, adapterlimit, len); usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); 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 (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) + adapterlimit = I2C_SMBUS_BLOCK_MAX; } + if (rc <= 0) + goto out; } out: -- 2.9.3