[PATCH v2 3/3] iio: light: ltr390: Calculate 'counts_per_uvi' dynamically

[Abhash Jha <abhashkumarjha123@gmail.com>]

    counts_per_uvi depends on the current value of gain and
    resolution. Hence we cannot use the hardcoded value of 96.
    The `counts_per_uvi` function gives the count based on the
    current gain and resolution (integration time).

Signed-off-by: Abhash Jha <abhashkumarjha123@gmail.com>
---
 drivers/iio/light/ltr390.c | 41 ++++++++++++++++++++++++++++----------
 1 file changed, 31 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/light/ltr390.c b/drivers/iio/light/ltr390.c
index d1a259141..aceb97e3d 100644
--- a/drivers/iio/light/ltr390.c
+++ b/drivers/iio/light/ltr390.c
@@ -45,6 +45,8 @@
 #define LTR390_UVS_MODE	      BIT(3)
 #define LTR390_SENSOR_ENABLE  BIT(1)
 
+#define LTR390_FRACTIONAL_PRECISION 100
+
 /*
  * At 20-bit resolution (integration time: 400ms) and 18x gain, 2300 counts of
  * the sensor are equal to 1 UV Index [Datasheet Page#8].
@@ -122,6 +124,19 @@ static int ltr390_set_mode(struct ltr390_data *data, int mode)
 	return 0;
 }
 
+static int ltr390_counts_per_uvi(struct ltr390_data *data)
+{
+	int orig_gain = 18;
+	int orig_int_time = 400;
+	int divisor = orig_gain * orig_int_time;
+	int gain = data->gain;
+
+	int int_time_ms = DIV_ROUND_CLOSEST(data->int_time_us, 1000);
+	int uvi = DIV_ROUND_CLOSEST(2300 * gain * int_time_ms, divisor);
+
+	return uvi;
+}
+
 static int ltr390_read_raw(struct iio_dev *iio_device,
 			   struct iio_chan_spec const *chan, int *val,
 			   int *val2, long mask)
@@ -167,8 +182,8 @@ static int ltr390_read_raw(struct iio_dev *iio_device,
 			if (ret < 0)
 				return ret;
 
-			*val = LTR390_WINDOW_FACTOR;
-			*val2 = LTR390_COUNTS_PER_UVI;
+			*val = LTR390_WINDOW_FACTOR * LTR390_FRACTIONAL_PRECISION;
+			*val2 = ltr390_counts_per_uvi(data);
 			return IIO_VAL_FRACTIONAL;
 
 		case IIO_INTENSITY:
@@ -202,17 +217,21 @@ static const struct iio_chan_spec ltr390_channels[] = {
 	{
 		.type = IIO_UVINDEX,
 		.scan_index = 0,
-		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+					BIT(IIO_CHAN_INFO_SCALE),
 		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
-		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) | BIT(IIO_CHAN_INFO_SCALE)
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) |
+							BIT(IIO_CHAN_INFO_SCALE)
 	},
 	/* ALS sensor */
 	{
 		.type = IIO_INTENSITY,
 		.scan_index = 1,
-		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+					BIT(IIO_CHAN_INFO_SCALE),
 		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
-		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) | BIT(IIO_CHAN_INFO_SCALE)
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME) |
+							BIT(IIO_CHAN_INFO_SCALE)
 	},
 };
 
@@ -261,8 +280,9 @@ static int ltr390_set_int_time(struct ltr390_data *data, int val)
 	return 0;
 }
 
-static int ltr390_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
-				const int **vals, int *type, int *length, long mask)
+static int ltr390_read_avail(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan,
+			const int **vals, int *type, int *length, long mask)
 {
 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE:
@@ -280,8 +300,9 @@ static int ltr390_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec con
 	}
 }
 
-static int ltr390_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
-				int val, int val2, long mask)
+static int ltr390_write_raw(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan,
+			int val, int val2, long mask)
 {
 	struct ltr390_data *data = iio_priv(indio_dev);
 
-- 
2.43.0