staging: iio: isl29028: fix incorrect sleep time when taking initial proximity reading

When proximity is enabled in isl29028_enable_proximity(), the function
msleep() is called with the sampling frequency, which is not correct.
This patch changes the code to sleep the specified amount of time listed
in the datasheet instead.
Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/light/isl29028.c

@@ -63,6 +63,9 @@
 
 #define ISL29028_POWER_OFF_DELAY_MS		2000
 
+static const unsigned int isl29028_prox_sleep_time[] = {800, 400, 200, 100, 75,
+							50, 12, 0};
+
 enum isl29028_als_ir_mode {
 	ISL29028_MODE_NONE = 0,
 	ISL29028_MODE_ALS,
@@ -78,22 +81,29 @@ struct isl29028_chip {
 	enum isl29028_als_ir_mode	als_ir_mode;
 };
 
-static int isl29028_set_proxim_sampling(struct isl29028_chip *chip,
-					unsigned int sampling)
+static int isl29028_find_prox_sleep_time_index(int sampling)
 {
-	struct device *dev = regmap_get_device(chip->regmap);
-	static unsigned int prox_period[] = {800, 400, 200, 100, 75, 50, 12, 0};
 	unsigned int period = DIV_ROUND_UP(1000, sampling);
-	int sel, ret;
+	int i;
 
-	for (sel = 0; sel < ARRAY_SIZE(prox_period); ++sel) {
-		if (period >= prox_period[sel])
+	for (i = 0; i < ARRAY_SIZE(isl29028_prox_sleep_time); ++i) {
+		if (period >= isl29028_prox_sleep_time[i])
 			break;
 	}
 
+	return i;
+}
+
+static int isl29028_set_proxim_sampling(struct isl29028_chip *chip,
+					unsigned int sampling)
+{
+	struct device *dev = regmap_get_device(chip->regmap);
+	int sleep_index, ret;
+
+	sleep_index = isl29028_find_prox_sleep_time_index(sampling);
 	ret = regmap_update_bits(chip->regmap, ISL29028_REG_CONFIGURE,
 				 ISL29028_CONF_PROX_SLP_MASK,
-				 sel << ISL29028_CONF_PROX_SLP_SH);
+				 sleep_index << ISL29028_CONF_PROX_SLP_SH);
 
 	if (ret < 0) {
 		dev_err(dev, "%s(): Error %d setting the proximity sampling\n",
@@ -108,7 +118,7 @@ static int isl29028_set_proxim_sampling(struct isl29028_chip *chip,
 
 static int isl29028_enable_proximity(struct isl29028_chip *chip)
 {
-	int ret;
+	int sleep_index, ret;
 
 	ret = isl29028_set_proxim_sampling(chip, chip->prox_sampling);
 	if (ret < 0)
@@ -121,7 +131,8 @@ static int isl29028_enable_proximity(struct isl29028_chip *chip)
 		return ret;
 
 	/* Wait for conversion to be complete for first sample */
-	msleep(DIV_ROUND_UP(1000, chip->prox_sampling));
+	sleep_index = isl29028_find_prox_sleep_time_index(chip->prox_sampling);
+	msleep(isl29028_prox_sleep_time[sleep_index]);
 
 	return 0;
 }