staging: iio: tsl2x7x: correct IIO_EV_INFO_PERIOD values

The thresh periods assumed an integration time of 3ms. This patch adds
support for the correct integration time (2.72ms or 2.73ms). The code
had the ALS filter values as going up to 15, however the values actually
went up to 60 since the values scaled in increments of 5 once the
persistence value went above 3.
Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/light/tsl2x7x.c

@@ -103,8 +103,6 @@
 #define TSL2X7X_CNTL_PROXPON_ENBL	0x0F
 #define TSL2X7X_CNTL_INTPROXPON_ENBL	0x2F
 
-#define TSL2X7X_MIN_ITIME		3
-
 /* TAOS txx2x7x Device family members */
 enum {
 	tsl2571,
@@ -984,7 +982,7 @@ static int tsl2x7x_write_event_value(struct iio_dev *indio_dev,
 				     int val, int val2)
 {
 	struct tsl2X7X_chip *chip = iio_priv(indio_dev);
-	int ret = -EINVAL, y, z, filter_delay;
+	int ret = -EINVAL, count, persistence;
 	u8 time;
 
 	switch (info) {
@@ -1023,15 +1021,20 @@ static int tsl2x7x_write_event_value(struct iio_dev *indio_dev,
 		else
 			time = chip->settings.prox_time;
 
-		y = (TSL2X7X_MAX_TIMER_CNT - time) + 1;
-		z = y * TSL2X7X_MIN_ITIME;
+		count = 256 - time;
+		persistence = ((val * 1000000) + val2) /
+			(count * tsl2x7x_int_time_avail[chip->id][3]);
 
-		filter_delay = DIV_ROUND_UP((val * 1000) + val2, z);
+		if (chan->type == IIO_INTENSITY) {
+			/* ALS filter values are 1, 2, 3, 5, 10, 15, ..., 60 */
+			if (persistence > 3)
+				persistence = (persistence / 5) + 3;
+
+			chip->settings.als_persistence = persistence;
+		} else {
+			chip->settings.prox_persistence = persistence;
+		}
 
-		if (chan->type == IIO_INTENSITY)
-			chip->settings.als_persistence = filter_delay;
-		else
-			chip->settings.prox_persistence = filter_delay;
 		ret = 0;
 		break;
 	default:
@@ -1052,7 +1055,7 @@ static int tsl2x7x_read_event_value(struct iio_dev *indio_dev,
 				    int *val, int *val2)
 {
 	struct tsl2X7X_chip *chip = iio_priv(indio_dev);
-	int filter_delay, mult;
+	int filter_delay, persistence;
 	u8 time;
 
 	switch (info) {
@@ -1084,18 +1087,21 @@ static int tsl2x7x_read_event_value(struct iio_dev *indio_dev,
 	case IIO_EV_INFO_PERIOD:
 		if (chan->type == IIO_INTENSITY) {
 			time = chip->settings.als_time;
-			mult = chip->settings.als_persistence;
+			persistence = chip->settings.als_persistence;
+
+			/* ALS filter values are 1, 2, 3, 5, 10, 15, ..., 60 */
+			if (persistence > 3)
+				persistence = (persistence - 3) * 5;
 		} else {
 			time = chip->settings.prox_time;
-			mult = chip->settings.prox_persistence;
+			persistence = chip->settings.prox_persistence;
 		}
 
-		/* Determine integration time */
-		*val = (TSL2X7X_MAX_TIMER_CNT - time) + 1;
-		*val2 = *val * TSL2X7X_MIN_ITIME;
-		filter_delay = *val2 * mult;
-		*val = filter_delay / 1000;
-		*val2 = filter_delay % 1000;
+		filter_delay = persistence * (256 - time) *
+			tsl2x7x_int_time_avail[chip->id][3];
+
+		*val = filter_delay / 1000000;
+		*val2 = filter_delay % 1000000;
 		return IIO_VAL_INT_PLUS_MICRO;
 	default:
 		return -EINVAL;

drivers/staging/iio/light/tsl2x7x.h

@@ -31,7 +31,6 @@ struct tsl2x7x_lux {
 #define TSL2X7X_50_mA                   0x01
 #define TSL2X7X_25_mA                   0x02
 #define TSL2X7X_13_mA                   0x03
-#define TSL2X7X_MAX_TIMER_CNT           0xFF
 
 /**
  * struct tsl2x7x_settings - Settings for the tsl2x7x driver