light: tsl2591: simplify tsl2591_persist functions via lookup table

Replace switch statements with an indexed lookup table for
persist cycle conversions.

Both functions contain redundant switch statements. This
reduces code duplication and makes future updates to
TSL2591_PRST_ALS_INT_CYCLE_* definitions easier to maintain
by keeping the mapping in a single place.

Signed-off-by: Matheus Silveira <matheus.feitosa@usp.br>
Co-developed-by: Lucas Rabaquim <lucas.rabaquim@usp.br>
Signed-off-by: Lucas Rabaquim <lucas.rabaquim@usp.br>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Author: MatheusSilver

drivers/iio/light/tsl2591.c

@@ -192,6 +192,24 @@ static const int tsl2591_calibscale_available[] = {
 	1, 25, 428, 9876,
 };
 
+static const u8 tsl2591_persist_table[] = {
+	[TSL2591_PRST_ALS_INT_CYCLE_ANY] = 1,
+	[TSL2591_PRST_ALS_INT_CYCLE_2]   = 2,
+	[TSL2591_PRST_ALS_INT_CYCLE_3]   = 3,
+	[TSL2591_PRST_ALS_INT_CYCLE_5]   = 5,
+	[TSL2591_PRST_ALS_INT_CYCLE_10]  = 10,
+	[TSL2591_PRST_ALS_INT_CYCLE_15]  = 15,
+	[TSL2591_PRST_ALS_INT_CYCLE_20]  = 20,
+	[TSL2591_PRST_ALS_INT_CYCLE_25]  = 25,
+	[TSL2591_PRST_ALS_INT_CYCLE_30]  = 30,
+	[TSL2591_PRST_ALS_INT_CYCLE_35]  = 35,
+	[TSL2591_PRST_ALS_INT_CYCLE_40]  = 40,
+	[TSL2591_PRST_ALS_INT_CYCLE_45]  = 45,
+	[TSL2591_PRST_ALS_INT_CYCLE_50]  = 50,
+	[TSL2591_PRST_ALS_INT_CYCLE_55]  = 55,
+	[TSL2591_PRST_ALS_INT_CYCLE_60]  = 60,
+};
+
 static int tsl2591_set_als_lower_threshold(struct tsl2591_chip *chip,
 					   u16 als_lower_threshold);
 static int tsl2591_set_als_upper_threshold(struct tsl2591_chip *chip,
@@ -231,78 +249,22 @@ static int tsl2591_multiplier_to_gain(const u32 multiplier)
 
 static int tsl2591_persist_cycle_to_lit(const u8 als_persist)
 {
-	switch (als_persist) {
-	case TSL2591_PRST_ALS_INT_CYCLE_ANY:
-		return 1;
-	case TSL2591_PRST_ALS_INT_CYCLE_2:
-		return 2;
-	case TSL2591_PRST_ALS_INT_CYCLE_3:
-		return 3;
-	case TSL2591_PRST_ALS_INT_CYCLE_5:
-		return 5;
-	case TSL2591_PRST_ALS_INT_CYCLE_10:
-		return 10;
-	case TSL2591_PRST_ALS_INT_CYCLE_15:
-		return 15;
-	case TSL2591_PRST_ALS_INT_CYCLE_20:
-		return 20;
-	case TSL2591_PRST_ALS_INT_CYCLE_25:
-		return 25;
-	case TSL2591_PRST_ALS_INT_CYCLE_30:
-		return 30;
-	case TSL2591_PRST_ALS_INT_CYCLE_35:
-		return 35;
-	case TSL2591_PRST_ALS_INT_CYCLE_40:
-		return 40;
-	case TSL2591_PRST_ALS_INT_CYCLE_45:
-		return 45;
-	case TSL2591_PRST_ALS_INT_CYCLE_50:
-		return 50;
-	case TSL2591_PRST_ALS_INT_CYCLE_55:
-		return 55;
-	case TSL2591_PRST_ALS_INT_CYCLE_60:
-		return 60;
-	default:
+	if (als_persist >= ARRAY_SIZE(tsl2591_persist_table) ||
+	    !tsl2591_persist_table[als_persist])
 		return -EINVAL;
-	}
+
+	return tsl2591_persist_table[als_persist];
 }
 
 static int tsl2591_persist_lit_to_cycle(const u8 als_persist)
 {
-	switch (als_persist) {
-	case 1:
-		return TSL2591_PRST_ALS_INT_CYCLE_ANY;
-	case 2:
-		return TSL2591_PRST_ALS_INT_CYCLE_2;
-	case 3:
-		return TSL2591_PRST_ALS_INT_CYCLE_3;
-	case 5:
-		return TSL2591_PRST_ALS_INT_CYCLE_5;
-	case 10:
-		return TSL2591_PRST_ALS_INT_CYCLE_10;
-	case 15:
-		return TSL2591_PRST_ALS_INT_CYCLE_15;
-	case 20:
-		return TSL2591_PRST_ALS_INT_CYCLE_20;
-	case 25:
-		return TSL2591_PRST_ALS_INT_CYCLE_25;
-	case 30:
-		return TSL2591_PRST_ALS_INT_CYCLE_30;
-	case 35:
-		return TSL2591_PRST_ALS_INT_CYCLE_35;
-	case 40:
-		return TSL2591_PRST_ALS_INT_CYCLE_40;
-	case 45:
-		return TSL2591_PRST_ALS_INT_CYCLE_45;
-	case 50:
-		return TSL2591_PRST_ALS_INT_CYCLE_50;
-	case 55:
-		return TSL2591_PRST_ALS_INT_CYCLE_55;
-	case 60:
-		return TSL2591_PRST_ALS_INT_CYCLE_60;
-	default:
-		return -EINVAL;
+	for (unsigned int i = TSL2591_PRST_ALS_INT_CYCLE_ANY;
+	     i < ARRAY_SIZE(tsl2591_persist_table); i++) {
+		if (als_persist == tsl2591_persist_table[i])
+			return i;
 	}
+
+	return -EINVAL;
 }
 
 static int tsl2591_compatible_int_time(struct tsl2591_chip *chip,