Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755552Ab2EBPRo (ORCPT ); Wed, 2 May 2012 11:17:44 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:34717 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754294Ab2EBPRm (ORCPT ); Wed, 2 May 2012 11:17:42 -0400 Date: Wed, 2 May 2012 17:17:34 +0200 From: Andi Shyti To: Peter Huewe Cc: Rajiv Andrade , tpmdd@selhorst.net, tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Olof Johansson , Luigi Semenzato , Bryan Freed Subject: Re: [PATCH] CHROMIUM: tpm: tpm_tis_i2c: Lock the I2C adapter for a sequence of requests. Message-ID: <20120502151734.GD16981@andi> Mail-Followup-To: Peter Huewe , Rajiv Andrade , tpmdd@selhorst.net, tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Olof Johansson , Luigi Semenzato , Bryan Freed References: <1335967293-7728-1-git-send-email-peter.huewe@infineon.com> <1335967416-7564-1-git-send-email-peter.huewe@infineon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1335967416-7564-1-git-send-email-peter.huewe@infineon.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4388 Lines: 138 Hi again :), On Wed, May 02, 2012 at 04:03:36PM +0200, Peter Huewe wrote: > From: Bryan Freed > > This is derived from Peter Huewe's recommended fix: > > On some ChromeOS systems, a TPM sharing the I2C bus with another device > gets confused when it sees I2C requests to that other device. > This change locks the I2C adapter for the duration of the full sequence > of I2C requests the TPM needs to complete. > > smbus_xfer is not supported, but SMBUS is not supported by the original > driver, either. > > Signed-off-by: Bryan Freed > Signed-off-by: Peter Huewe > --- > drivers/char/tpm/tpm_tis_i2c.c | 42 ++++++++++++++++++++++++++++++++++++--- > 1 files changed, 38 insertions(+), 4 deletions(-) > > diff --git a/drivers/char/tpm/tpm_tis_i2c.c b/drivers/char/tpm/tpm_tis_i2c.c > index 8975abf..e68f209 100644 > --- a/drivers/char/tpm/tpm_tis_i2c.c > +++ b/drivers/char/tpm/tpm_tis_i2c.c > @@ -61,6 +61,28 @@ static struct tpm_inf_dev tpm_dev; > > > /* > + * Copy i2c-core:i2c_transfer() as close as possible without the adapter locks > + * and algorithm check. These are done by the caller for atomicity. > + */ > +static int i2c_transfer_nolock(struct i2c_adapter *adap, struct i2c_msg *msgs, > + int num) > +{ > + unsigned long orig_jiffies; > + int ret, try; > + > + /* Retry automatically on arbitration loss */ > + orig_jiffies = jiffies; > + for (ret = 0, try = 0; try <= adap->retries; try++) { > + ret = adap->algo->master_xfer(adap, msgs, num); > + if (ret != -EAGAIN) > + break; > + if (time_after(jiffies, orig_jiffies + adap->timeout)) > + break; > + } > + return ret; > +} > + > +/* > * iic_tpm_read() - read from TPM register > * @addr: register address to read from > * @buffer: provided by caller > @@ -83,8 +105,13 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) > int rc; > int count; > > + /* 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); > + > for (count = 0; count < MAX_COUNT; count++) { > - rc = i2c_transfer(tpm_dev.client->adapter, &msg1, 1); > + rc = i2c_transfer_nolock(tpm_dev.client->adapter, &msg1, 1); > if (rc > 0) > break; /* break here to skip sleep */ > > @@ -92,19 +119,21 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) > } > > if (rc <= 0) > - return -EIO; > + 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++) { > usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); > - rc = i2c_transfer(tpm_dev.client->adapter, &msg2, 1); > + rc = i2c_transfer_nolock(tpm_dev.client->adapter, &msg2, 1); > if (rc > 0) > break; > > } > > +out: > + i2c_unlock_adapter(tpm_dev.client->adapter); > if (rc <= 0) > return -EIO; > > @@ -121,17 +150,22 @@ static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t len, > > struct i2c_msg msg1 = { tpm_dev.client->addr, 0, len + 1, tpm_dev.buf }; > > + if (!tpm_dev.client->adapter->algo->master_xfer) > + return -EOPNOTSUPP; > + i2c_lock_adapter(tpm_dev.client->adapter); > + > tpm_dev.buf[0] = addr; > memcpy(&(tpm_dev.buf[1]), buffer, len); > > for (count = 0; count < max_count; count++) { > - rc = i2c_transfer(tpm_dev.client->adapter, &msg1, 1); > + rc = i2c_transfer_nolock(tpm_dev.client->adapter, &msg1, 1); > if (rc > 0) > break; > > usleep_range(sleep_low, sleep_hi); > } > > + i2c_unlock_adapter(tpm_dev.client->adapter); > if (rc <= 0) > return -EIO; > try to have a look to the i2c_smbus* function, you could avoid lot of code Andi > -- > 1.7.6.msysgit.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/