On Wed, 30 Apr 2014, Doug Anderson wrote:
> 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 <dianders@xxxxxxxxxxxx>
> Acked-by: Lee Jones <lee.jones@xxxxxxxxxx>
> Reviewed-by: Simon Glass <sjg@xxxxxxxxxxxx>
> Tested-by: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
> Tested-by: Stephen Warren <swarren@xxxxxxxxxx>
> ---
> Changes in v3: None
> Changes in v2: None
>
> drivers/mfd/cros_ec_spi.c | 26 +++++++++++++++++++++-----
> 1 file changed, 21 insertions(+), 5 deletions(-)
Applied, thanks.
> 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;
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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