[RFC] staging: iio: ad7759: Replace mlock with driver private buf_lock

[Arushi 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.  Replace it with a buf_lock in the devices global data.

Signed-off-by: Arushi Singhal <arushisinghal19971997@xxxxxxxxx>
---
 drivers/staging/iio/meter/ade7759.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/iio/meter/ade7759.c b/drivers/staging/iio/meter/ade7759.c
index 0b65f1847510..514a4f6bb8f9 100644
--- a/drivers/staging/iio/meter/ade7759.c
+++ b/drivers/staging/iio/meter/ade7759.c
@@ -429,7 +429,7 @@ static ssize_t ade7759_write_frequency(struct device *dev,
 	if (!val)
 		return -EINVAL;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&st->buf_lock);
 
 	t = 27900 / val;
 	if (t > 0)
@@ -447,10 +447,13 @@ static ssize_t ade7759_write_frequency(struct device *dev,
 	reg &= ~(3 << 13);
 	reg |= t << 13;
 
-	ret = ade7759_spi_write_reg_16(dev, ADE7759_MODE, reg);
+	st->tx[0] = ADE7754_WRITE_REG(ADE7754_WAVMODE);
+	st->tx[1] = reg;
+
+	ret = spi_write(st->us, st->tx, 2);
 
 out:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&st->buf_lock);
 
 	return ret ? ret : len;
 }
-- 
2.11.0