[PATCH v8] staging: adis16060: Remove iio_dev mlock and refactor code

[simran singhal]

The IIO subsystem is redefining iio_dev->mlock to be used by
the IIO core only for protecting device operating mode changes.
ie. Changes between INDIO_DIRECT_MODE, INDIO_BUFFER_* modes.

In this driver, mlock was being used to protect hardware state changes.

In the driver, buf_lock protects both the adis16060_spi_write() and
adis16060_spi_read() functions and both are always called in
pair. First write, then read. Refactor the code to have
one single function adis16060_spi_write_than_read() and remove
the use of mlock as adis16060_read_raw() does not require an
iio_dev->mlock for reads.

Signed-off-by: simran singhal <singhalsimran0 at gmail.com>
---

 v8:
   -change subject
   -change commit message
 v7:
   -Change subject
   -Remove lock from read_raw instead from
    function adis16060_spi_write_than_read().
 v6:
   -Change commit message
   -Remove nested lock
 v5:
   -Rename val in adis16060_spi_write_than_read() to conf.
   -Rename val2 in adis16060_spi_write_than_read() to val.
   -Corrected Checkpatch issues.
   -Removed goto from adis16060_read_raw().
 v4:
   -Refactored code
   -change commit subject
   -change commit message
 v3:
   -Removed new lock to reuse the existing lock
 v2:
   -Fixed compilation error

 drivers/staging/iio/gyro/adis16060_core.c | 33 ++++++++-----------------------
 1 file changed, 8 insertions(+), 25 deletions(-)

diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c
index c9d46e7..e96fce5 100644
--- a/drivers/staging/iio/gyro/adis16060_core.c
+++ b/drivers/staging/iio/gyro/adis16060_core.c
@@ -40,25 +40,18 @@ struct adis16060_state {
 
 static struct iio_dev *adis16060_iio_dev;
 
-static int adis16060_spi_write(struct iio_dev *indio_dev, u8 val)
+static int adis16060_spi_write_than_read(struct iio_dev *indio_dev,
+					 u8 conf, u16 *val)
 {
 	int ret;
 	struct adis16060_state *st = iio_priv(indio_dev);
 
 	mutex_lock(&st->buf_lock);
-	st->buf[2] = val; /* The last 8 bits clocked in are latched */
+	st->buf[2] = conf; /* The last 8 bits clocked in are latched */
 	ret = spi_write(st->us_w, st->buf, 3);
-	mutex_unlock(&st->buf_lock);
-
-	return ret;
-}
-
-static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val)
-{
-	int ret;
-	struct adis16060_state *st = iio_priv(indio_dev);
 
-	mutex_lock(&st->buf_lock);
+	if (ret < 0)
+		return ret;
 
 	ret = spi_read(st->us_r, st->buf, 3);
 
@@ -86,17 +79,11 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
-		/* Take the iio_dev status lock */
-		mutex_lock(&indio_dev->mlock);
-		ret = adis16060_spi_write(indio_dev, chan->address);
+		ret = adis16060_spi_write_than_read(indio_dev,
+						    chan->address, &tval);
 		if (ret < 0)
-			goto out_unlock;
+			return ret;
 
-		ret = adis16060_spi_read(indio_dev, &tval);
-		if (ret < 0)
-			goto out_unlock;
-
-		mutex_unlock(&indio_dev->mlock);
 		*val = tval;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_OFFSET:
@@ -110,10 +97,6 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
 	}
 
 	return -EINVAL;
-
-out_unlock:
-	mutex_unlock(&indio_dev->mlock);
-	return ret;
 }
 
 static const struct iio_info adis16060_info = {
-- 
2.7.4