iio: light: bu27034: Fix scale format

The driver is expecting accuracy of NANOs for intensity scale in
raw_write. The IIO core is however defaulting to MICROs. This leads the
raw-write of smallest scales to never succeed as correct selector(s) are
not found.

Fix this by implementing the .write_raw_get_fmt callback to use NANO
accuracy for writes of IIO_CHAN_INFO_SCALE.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Fixes: e52afbd ("iio: light: ROHM BU27034 Ambient Light Sensor")
Link: https://lore.kernel.org/r/5369117315cf05b88cf0ccb87373fd77190f6ca2.1686648422.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: M-Vaittinen

drivers/iio/light/rohm-bu27034.c

@@ -575,7 +575,7 @@ static int bu27034_set_scale(struct bu27034_data *data, int chan,
 		return -EINVAL;
 
 	if (chan == BU27034_CHAN_ALS) {
-		if (val == 0 && val2 == 1000)
+		if (val == 0 && val2 == 1000000)
 			return 0;
 
 		return -EINVAL;
@@ -587,7 +587,7 @@ static int bu27034_set_scale(struct bu27034_data *data, int chan,
 		goto unlock_out;
 
 	ret = iio_gts_find_gain_sel_for_scale_using_time(&data->gts, time_sel,
-						val, val2 * 1000, &gain_sel);
+						val, val2, &gain_sel);
 	if (ret) {
 		/*
 		 * Could not support scale with given time. Need to change time.
@@ -624,7 +624,7 @@ static int bu27034_set_scale(struct bu27034_data *data, int chan,
 
 			/* Can we provide requested scale with this time? */
 			ret = iio_gts_find_gain_sel_for_scale_using_time(
-				&data->gts, new_time_sel, val, val2 * 1000,
+				&data->gts, new_time_sel, val, val2,
 				&gain_sel);
 			if (ret)
 				continue;
@@ -1217,6 +1217,21 @@ static int bu27034_read_raw(struct iio_dev *idev,
 	}
 }
 
+static int bu27034_write_raw_get_fmt(struct iio_dev *indio_dev,
+				     struct iio_chan_spec const *chan,
+				     long mask)
+{
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_INT_TIME:
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
 static int bu27034_write_raw(struct iio_dev *idev,
 			     struct iio_chan_spec const *chan,
 			     int val, int val2, long mask)
@@ -1267,6 +1282,7 @@ static int bu27034_read_avail(struct iio_dev *idev,
 static const struct iio_info bu27034_info = {
 	.read_raw = &bu27034_read_raw,
 	.write_raw = &bu27034_write_raw,
+	.write_raw_get_fmt = &bu27034_write_raw_get_fmt,
 	.read_avail = &bu27034_read_avail,
 };