iio: hid-sensor-attributes: Convert to use int_pow()

Instead of linear approach to calculate power of 10, use generic int_pow()
which does it better.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
index a8a3fe4..b9dd19b 100644 (file)
--- a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
+++ b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
@@ -8,6 +8,7 @@
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/hid-sensor-hub.h>
 #include <linux/iio/iio.h>
@@ -68,16 +69,6 @@ static struct {
        {HID_USAGE_SENSOR_HUMIDITY, 0, 1000, 0},
 };
 
-static int pow_10(unsigned power)
-{
-       int i;
-       int ret = 1;
-       for (i = 0; i < power; ++i)
-               ret = ret * 10;
-
-       return ret;
-}
-
 static void simple_div(int dividend, int divisor, int *whole,
                                int *micro_frac)
 {
@@ -96,14 +87,14 @@ static void simple_div(int dividend, int divisor, int *whole,
                        rem *= 10;
                        exp++;
                }
-               *micro_frac = (rem / divisor) * pow_10(6-exp);
+               *micro_frac = (rem / divisor) * int_pow(10, 6 - exp);
        }
 }
 
 static void split_micro_fraction(unsigned int no, int exp, int *val1, int *val2)
 {
-       *val1 = no/pow_10(exp);
-       *val2 = no%pow_10(exp) * pow_10(6-exp);
+       *val1 = no / int_pow(10, exp);
+       *val2 = no % int_pow(10, exp) * int_pow(10, 6 - exp);
 }
 
 /*
@@ -125,7 +116,7 @@ static void convert_from_vtf_format(u32 value, int size, int exp,
        }
        exp = hid_sensor_convert_exponent(exp);
        if (exp >= 0) {
-               *val1 = sign * value * pow_10(exp);
+               *val1 = sign * value * int_pow(10, exp);
                *val2 = 0;
        } else {
                split_micro_fraction(value, -exp, val1, val2);
@@ -145,10 +136,10 @@ static u32 convert_to_vtf_format(int size, int exp, int val1, int val2)
                sign = -1;
        exp = hid_sensor_convert_exponent(exp);
        if (exp < 0) {
-               value = abs(val1) * pow_10(-exp);
-               value += abs(val2) / pow_10(6+exp);
+               value = abs(val1) * int_pow(10, -exp);
+               value += abs(val2) / int_pow(10, 6 + exp);
        } else
-               value = abs(val1) / pow_10(exp);
+               value = abs(val1) / int_pow(10, exp);
        if (sign < 0)
                value =  ((1LL << (size * 8)) - value);
 
@@ -211,12 +202,12 @@ int hid_sensor_write_samp_freq_value(struct hid_sensor_common *st,
        if (val1 < 0 || val2 < 0)
                return -EINVAL;
 
-       value = val1 * pow_10(6) + val2;
+       value = val1 * int_pow(10, 6) + val2;
        if (value) {
                if (st->poll.units == HID_USAGE_SENSOR_UNITS_MILLISECOND)
-                       value = pow_10(9)/value;
+                       value = int_pow(10, 9) / value;
                else if (st->poll.units == HID_USAGE_SENSOR_UNITS_SECOND)
-                       value = pow_10(6)/value;
+                       value = int_pow(10, 6) / value;
                else
                        value = 0;
        }
@@ -311,34 +302,34 @@ static void adjust_exponent_nano(int *val0, int *val1, int scale0,
        int rem;
 
        if (exp > 0) {
-               *val0 = scale0 * pow_10(exp);
+               *val0 = scale0 * int_pow(10, exp);
                res = 0;
                if (exp > 9) {
                        *val1 = 0;
                        return;
                }
                for (i = 0; i < exp; ++i) {
-                       x = scale1 / pow_10(8 - i);
-                       res += (pow_10(exp - 1 - i) * x);
-                       scale1 = scale1 % pow_10(8 - i);
+                       x = scale1 / int_pow(10, 8 - i);
+                       res += int_pow(10, exp - 1 - i) * x;
+                       scale1 = scale1 % int_pow(10, 8 - i);
                }
                *val0 += res;
-               *val1 = scale1 * pow_10(exp);
+               *val1 = scale1 * int_pow(10, exp);
        } else if (exp < 0) {
                exp = abs(exp);
                if (exp > 9) {
                        *val0 = *val1 = 0;
                        return;
                }
-               *val0 = scale0 / pow_10(exp);
-               rem = scale0 % pow_10(exp);
+               *val0 = scale0 / int_pow(10, exp);
+               rem = scale0 % int_pow(10, exp);
                res = 0;
                for (i = 0; i < (9 - exp); ++i) {
-                       x = scale1 / pow_10(8 - i);
-                       res += (pow_10(8 - exp - i) * x);
-                       scale1 = scale1 % pow_10(8 - i);
+                       x = scale1 / int_pow(10, 8 - i);
+                       res += int_pow(10, 8 - exp - i) * x;
+                       scale1 = scale1 % int_pow(10, 8 - i);
                }
-               *val1 = rem * pow_10(9 - exp) + res;
+               *val1 = rem * int_pow(10, 9 - exp) + res;
        } else {
                *val0 = scale0;
                *val1 = scale1;