hwmon: (adt7473) Fix voltage conversion routines

Fix voltage conversion routines. Based on an earlier patch from
Paulius Zaleckas.

According to the datasheet voltage is scaled with resistors and
value 192 is nominal voltage. 0 is 0V.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
Cc: Darrick J. Wong <djwong@us.ibm.com>

diff --git a/drivers/hwmon/adt7473.c b/drivers/hwmon/adt7473.c
index 3a0b63136479d7c4c701dc8eb6e3652e033c1831..b9a8ea30c99c822542682017fc40a4c83e99b4f7 100644 (file)
--- a/drivers/hwmon/adt7473.c
+++ b/drivers/hwmon/adt7473.c
@@ -319,35 +319,24 @@ out:
 }
 
 /*
- * On this chip, voltages are given as a count of steps between a minimum
- * and maximum voltage, not a direct voltage.
+ * Conversions
  */
-static const int volt_convert_table[][2] = {
-       {2997, 3},
-       {4395, 4},
+
+/* IN are scaled acording to built-in resistors */
+static const int adt7473_scaling[] = {  /* .001 Volts */
+       2250, 3300
 };
+#define SCALE(val, from, to)   (((val) * (to) + ((from) / 2)) / (from))
 
 static int decode_volt(int volt_index, u8 raw)
 {
-       int cmax = volt_convert_table[volt_index][0];
-       int cmin = volt_convert_table[volt_index][1];
-       return ((raw * (cmax - cmin)) / 255) + cmin;
+       return SCALE(raw, 192, adt7473_scaling[volt_index]);
 }
 
 static u8 encode_volt(int volt_index, int cooked)
 {
-       int cmax = volt_convert_table[volt_index][0];
-       int cmin = volt_convert_table[volt_index][1];
-       u8 x;
-
-       if (cooked > cmax)
-               cooked = cmax;
-       else if (cooked < cmin)
-               cooked = cmin;
-
-       x = ((cooked - cmin) * 255) / (cmax - cmin);
-
-       return x;
+       int raw = SCALE(cooked, adt7473_scaling[volt_index], 192);
+       return SENSORS_LIMIT(raw, 0, 255);
 }
 
 static ssize_t show_volt_min(struct device *dev,