iio:magnetometer:mag3110: Report busy in _read_raw() / write_raw() when buffer is enabled

individual reads are not permitted concurrently with buffered reads
Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/magnetometer/mag3110.c

@@ -154,6 +154,9 @@ static int mag3110_read_raw(struct iio_dev *indio_dev,
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
+		if (iio_buffer_enabled(indio_dev))
+			return -EBUSY;
+
 		switch (chan->type) {
 		case IIO_MAGN: /* in 0.1 uT / LSB */
 			ret = mag3110_read(data, buffer);
@@ -199,6 +202,9 @@ static int mag3110_write_raw(struct iio_dev *indio_dev,
 	struct mag3110_data *data = iio_priv(indio_dev);
 	int rate;
 
+	if (iio_buffer_enabled(indio_dev))
+		return -EBUSY;
+
 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		rate = mag3110_get_samp_freq_index(data, val, val2);