From 6d6e44a953161e4ce60d1fe805d165d8290ce9e8 Mon Sep 17 00:00:00 2001 From: Nicolas Boichat Date: Wed, 25 Nov 2015 13:51:07 +0800 Subject: mfd: cros ec: Lock the SPI bus while holding chipselect cros_ec_cmd_xfer_spi and cros_ec_pkt_xfer_spi generally work like this: - Pull CS down (active), wait a bit, then send a command - Wait for response (multiple requests) - Wait a while, pull CS up (inactive) These operations, individually, lock the SPI bus, but there is nothing preventing the SPI framework from interleaving messages intended for other devices as the bus is unlocked in between. This is a problem as the EC expects CS to be held low for the whole duration. Solution: Lock the SPI bus during the whole transaction, to make sure that no other messages can be interleaved. Signed-off-by: Nicolas Boichat Reviewed-by: Gwendal Grignou Signed-off-by: Lee Jones --- drivers/mfd/cros_ec_spi.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) (limited to 'drivers/mfd/cros_ec_spi.c') diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index 6a0f6ec67c6b..d6af52d18c06 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c @@ -113,7 +113,7 @@ static int terminate_request(struct cros_ec_device *ec_dev) trans.delay_usecs = ec_spi->end_of_msg_delay; spi_message_add_tail(&trans, &msg); - ret = spi_sync(ec_spi->spi, &msg); + ret = spi_sync_locked(ec_spi->spi, &msg); /* Reset end-of-response timer */ ec_spi->last_transfer_ns = ktime_get_ns(); @@ -147,7 +147,7 @@ static int receive_n_bytes(struct cros_ec_device *ec_dev, u8 *buf, int n) spi_message_init(&msg); spi_message_add_tail(&trans, &msg); - ret = spi_sync(ec_spi->spi, &msg); + ret = spi_sync_locked(ec_spi->spi, &msg); if (ret < 0) dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret); @@ -391,10 +391,10 @@ static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev, } rx_buf = kzalloc(len, GFP_KERNEL); - if (!rx_buf) { - ret = -ENOMEM; - goto exit; - } + if (!rx_buf) + return -ENOMEM; + + spi_bus_lock(ec_spi->spi->master); /* * Leave a gap between CS assertion and clocking of data to allow the @@ -414,7 +414,7 @@ static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev, trans.len = len; trans.cs_change = 1; spi_message_add_tail(&trans, &msg); - ret = spi_sync(ec_spi->spi, &msg); + ret = spi_sync_locked(ec_spi->spi, &msg); /* Get the response */ if (!ret) { @@ -440,6 +440,9 @@ static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev, } final_ret = terminate_request(ec_dev); + + spi_bus_unlock(ec_spi->spi->master); + if (!ret) ret = final_ret; if (ret < 0) @@ -520,10 +523,10 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev, } rx_buf = kzalloc(len, GFP_KERNEL); - if (!rx_buf) { - ret = -ENOMEM; - goto exit; - } + if (!rx_buf) + return -ENOMEM; + + spi_bus_lock(ec_spi->spi->master); /* Transmit phase - send our message */ debug_packet(ec_dev->dev, "out", ec_dev->dout, len); @@ -534,7 +537,7 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev, trans.cs_change = 1; spi_message_init(&msg); spi_message_add_tail(&trans, &msg); - ret = spi_sync(ec_spi->spi, &msg); + ret = spi_sync_locked(ec_spi->spi, &msg); /* Get the response */ if (!ret) { @@ -560,6 +563,9 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev, } final_ret = terminate_request(ec_dev); + + spi_bus_unlock(ec_spi->spi->master); + if (!ret) ret = final_ret; if (ret < 0) -- cgit v1.2.3