Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752808AbaDQSB1 (ORCPT ); Thu, 17 Apr 2014 14:01:27 -0400 Received: from mail-yh0-f74.google.com ([209.85.213.74]:39635 "EHLO mail-yh0-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751725AbaDQSAU (ORCPT ); Thu, 17 Apr 2014 14:00:20 -0400 From: Doug Anderson To: Lee Jones , Stephen Warren , Wolfram Sang Cc: abrestic@chromium.org, dgreid@chromium.org, Olof Johansson , Simon Glass , linux-samsung-soc@vger.kernel.org, linux-tegra@vger.kernel.org, Doug Anderson , Samuel Ortiz , linux-kernel@vger.kernel.org Subject: [PATCH 2/7] mfd: cros_ec: spi: Add mutex to cros_ec_spi Date: Thu, 17 Apr 2014 10:59:25 -0700 Message-Id: <1397757570-19750-3-git-send-email-dianders@chromium.org> X-Mailer: git-send-email 1.9.1.423.g4596e3a In-Reply-To: <1397757570-19750-1-git-send-email-dianders@chromium.org> References: <1397757570-19750-1-git-send-email-dianders@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The main transfer function for cros_ec_spi can be called by more than one client at a time. Make sure that those clients don't stomp on each other by locking the bus for the duration of the transfer function. Signed-off-by: Doug Anderson --- drivers/mfd/cros_ec_spi.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index c185eb6..a2a605d 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c @@ -65,11 +65,13 @@ * if no record * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that * is sent when we want to turn off CS at the end of a transaction. + * @lock: mutex to ensure only one user of cros_ec_command_spi_xfer at a time */ struct cros_ec_spi { struct spi_device *spi; s64 last_transfer_ns; unsigned int end_of_msg_delay; + struct mutex lock; }; static void debug_packet(struct device *dev, const char *name, u8 *ptr, @@ -208,6 +210,13 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, int ret = 0, final_ret; struct timespec ts; + /* + * We have the shared ec_dev buffer plus we do lots of separate spi_sync + * calls, so we need to make sure only one person is using this at a + * time. + */ + mutex_lock(&ec_spi->lock); + len = cros_ec_prepare_tx(ec_dev, ec_msg); dev_dbg(ec_dev->dev, "prepared, len=%d\n", len); @@ -260,7 +269,7 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, ret = final_ret; if (ret < 0) { dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret); - return ret; + goto exit; } /* check response error code */ @@ -269,14 +278,16 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, dev_warn(ec_dev->dev, "command 0x%02x returned an error %d\n", ec_msg->cmd, ptr[0]); debug_packet(ec_dev->dev, "in_err", ptr, len); - return -EINVAL; + ret = -EINVAL; + goto exit; } len = ptr[1]; sum = ptr[0] + ptr[1]; if (len > ec_msg->in_len) { dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)", len, ec_msg->in_len); - return -ENOSPC; + ret = -ENOSPC; + goto exit; } /* copy response packet payload and compute checksum */ @@ -293,10 +304,14 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev, dev_err(ec_dev->dev, "bad packet checksum, expected %02x, got %02x\n", sum, ptr[len + 2]); - return -EBADMSG; + ret = -EBADMSG; + goto exit; } - return 0; + ret = 0; +exit: + mutex_unlock(&ec_spi->lock); + return ret; } static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev) @@ -327,6 +342,7 @@ static int cros_ec_spi_probe(struct spi_device *spi) if (ec_spi == NULL) return -ENOMEM; ec_spi->spi = spi; + mutex_init(&ec_spi->lock); ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL); if (!ec_dev) return -ENOMEM; -- 1.9.1.423.g4596e3a -- 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/