new macro: find_closest()

new file mode 100644
index 0000000..d5f4fb6
@@ -0,0 +1,40 @@
+#ifndef _LINUX_HELPER_MACROS_H_
+#define _LINUX_HELPER_MACROS_H_
+
+#define __find_closest(x, a, as, op)					\
+({									\
+	typeof(as) __fc_i, __fc_as = (as) - 1;				\
+	typeof(x) __fc_x = (x);						\
+	typeof(*a) *__fc_a = (a);					\
+	for (__fc_i = 0; __fc_i < __fc_as; __fc_i++) {			\
+		if (__fc_x op DIV_ROUND_CLOSEST(__fc_a[__fc_i] +	\
+						__fc_a[__fc_i + 1], 2))	\
+			break;						\
+	}								\
+	(__fc_i);							\
+})
+
+/**
+ * find_closest - locate the closest element in a sorted array
+ * @x: The reference value.
+ * @a: The array in which to look for the closest element. Must be sorted
+ *  in ascending order.
+ * @as: Size of 'a'.
+ *
+ * Returns the index of the element closest to 'x'.
+ */
+#define find_closest(x, a, as) __find_closest(x, a, as, <=)
+
+/**
+ * find_closest_descending - locate the closest element in a sorted array
+ * @x: The reference value.
+ * @a: The array in which to look for the closest element. Must be sorted
+ *  in descending order.
+ * @as: Size of 'a'.
+ *
+ * Similar to find_closest() but 'a' is expected to be sorted in descending
+ * order.
+ */
+#define find_closest_descending(x, a, as) __find_closest(x, a, as, >=)
+
+#endif

index d1542b7..4d28150 100644
@@ -36,6 +36,7 @@
 #include <linux/jiffies.h>
 #include <linux/of.h>
 #include <linux/delay.h>
+#include <linux/util_macros.h>
 
 #include <linux/platform_data/ina2xx.h>
 

@@ -141,19 +142,6 @@ static const struct ina2xx_config ina2xx_config[] = {
  */
 static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };
 
-static int ina226_avg_bits(int avg)
-{
-	int i;
-
-	/* Get the closest average from the tab. */
-	for (i = 0; i < ARRAY_SIZE(ina226_avg_tab) - 1; i++) {
-		if (avg <= (ina226_avg_tab[i] + ina226_avg_tab[i + 1]) / 2)
-			break;
-	}
-
-	return i; /* Return 0b0111 for values greater than 1024. */
-}
-
 static int ina226_reg_to_interval(u16 config)
 {
 	int avg = ina226_avg_tab[INA226_READ_AVG(config)];

@@ -171,7 +159,8 @@ static u16 ina226_interval_to_reg(int interval, u16 config)
 
 	avg = DIV_ROUND_CLOSEST(interval * 1000,
 				INA226_TOTAL_CONV_TIME_DEFAULT);
-	avg_bits = ina226_avg_bits(avg);
+	avg_bits = find_closest(avg, ina226_avg_tab,
+				ARRAY_SIZE(ina226_avg_tab));
 
 	return (config & ~INA226_AVG_RD_MASK) | INA226_SHIFT_AVG(avg_bits);
 }

index 2b4b419..6ff773f 100644
@@ -34,6 +34,7 @@
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <linux/util_macros.h>
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x2c, 0x2d, 0x2e, I2C_CLIENT_END };

@@ -190,15 +191,7 @@ static const int lm85_range_map[] = {
 
 static int RANGE_TO_REG(long range)
 {
-	int i;
-
-	/* Find the closest match */
-	for (i = 0; i < 15; ++i) {
-		if (range <= (lm85_range_map[i] + lm85_range_map[i + 1]) / 2)
-			break;
-	}
-
-	return i;
+	return find_closest(range, lm85_range_map, ARRAY_SIZE(lm85_range_map));
 }
 #define RANGE_FROM_REG(val)	lm85_range_map[(val) & 0x0f]
 

@@ -209,16 +202,12 @@ static const int lm85_freq_map[8] = { /* 1 Hz */
 static const int adm1027_freq_map[8] = { /* 1 Hz */
 	11, 15, 22, 29, 35, 44, 59, 88
 };
+#define FREQ_MAP_LEN	8
 
-static int FREQ_TO_REG(const int *map, unsigned long freq)
+static int FREQ_TO_REG(const int *map,
+		       unsigned int map_size, unsigned long freq)
 {
-	int i;
-
-	/* Find the closest match */
-	for (i = 0; i < 7; ++i)
-		if (freq <= (map[i] + map[i + 1]) / 2)
-			break;
-	return i;
+	return find_closest(freq, map, map_size);
 }
 
 static int FREQ_FROM_REG(const int *map, u8 reg)

@@ -828,7 +817,8 @@ static ssize_t set_pwm_freq(struct device *dev,
 		data->cfg5 &= ~ADT7468_HFPWM;
 		lm85_write_value(client, ADT7468_REG_CFG5, data->cfg5);
 	} else {					/* Low freq. mode */
-		data->pwm_freq[nr] = FREQ_TO_REG(data->freq_map, val);
+		data->pwm_freq[nr] = FREQ_TO_REG(data->freq_map,
+						 FREQ_MAP_LEN, val);
 		lm85_write_value(client, LM85_REG_AFAN_RANGE(nr),
 				 (data->zone[nr].range << 4)
 				 | data->pwm_freq[nr]);

index 2189413..49276bb 100644
@@ -35,6 +35,7 @@
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/jiffies.h>
+#include <linux/util_macros.h>
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = {

@@ -308,11 +309,8 @@ static u8 pwm_freq_to_reg(unsigned long val, u16 clkin)
 	unsigned long best0, best1;
 
 	/* Best fit for cksel = 0 */
-	for (reg0 = 0; reg0 < ARRAY_SIZE(pwm_freq_cksel0) - 1; reg0++) {
-		if (val > (pwm_freq_cksel0[reg0] +
-			   pwm_freq_cksel0[reg0 + 1]) / 2)
-			break;
-	}
+	reg0 = find_closest_descending(val, pwm_freq_cksel0,
+				       ARRAY_SIZE(pwm_freq_cksel0));
 	if (val < 375)	/* cksel = 1 can't beat this */
 		return reg0;
 	best0 = pwm_freq_cksel0[reg0];