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mfd: cros_ec: spi: Add mutex to cros_ec_spi

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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@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Andrew Bresticker <abrestic@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Doug Anderson 2014-04-30 10:44:05 -07:00 committed by Lee Jones
parent 1fe368665b
commit 362196e5d0
1 changed files with 21 additions and 5 deletions
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26
drivers/mfd/cros_ec_spi.c
View file

@ -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;