iio: imu: adis16480: use state lock for filter freq set

It's the only operation that does 2 operations (a read & a write), so the
unlocked functions can be used under a single state lock.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/adis16480.c

@@ -555,6 +555,7 @@ static int adis16480_set_filter_freq(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, unsigned int freq)
 {
 	struct adis16480 *st = iio_priv(indio_dev);
+	struct mutex *slock = &st->adis.state_lock;
 	unsigned int enable_mask, offset, reg;
 	unsigned int diff, best_diff;
 	unsigned int i, best_freq;
@@ -565,9 +566,11 @@ static int adis16480_set_filter_freq(struct iio_dev *indio_dev,
 	offset = ad16480_filter_data[chan->scan_index][1];
 	enable_mask = BIT(offset + 2);
 
-	ret = adis_read_reg_16(&st->adis, reg, &val);
+	mutex_lock(slock);
+
+	ret = __adis_read_reg_16(&st->adis, reg, &val);
 	if (ret)
-		return ret;
+		goto out_unlock;
 
 	if (freq == 0) {
 		val &= ~enable_mask;
@@ -589,7 +592,11 @@ static int adis16480_set_filter_freq(struct iio_dev *indio_dev,
 		val |= enable_mask;
 	}
 
-	return adis_write_reg_16(&st->adis, reg, val);
+	ret = __adis_write_reg_16(&st->adis, reg, val);
+out_unlock:
+	mutex_unlock(slock);
+
+	return ret;
 }
 
 static int adis16480_read_raw(struct iio_dev *indio_dev,