hwmon: (lm80) Simplify TEMP_FROM_REG

TEMP_FROM_REG gets 12 bits of temperature data in the upper 12 bit
of a signed 16 bit parameter, with the integer part (including sign)
in the upper 8 bit and the remainder in bit 4..7. The lower 4 bit of
the 16 bit data is always 0. We can use that information to convert
the temperature directly into display data (1/1000th of degree C).

Note that the stored temperature data is not shifted right as the
comment claimed, so remove that misleading comment.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/lm80.c b/drivers/hwmon/lm80.c
index bd0a1ebbf867c31be2ce98b6c45e766370eca5fe..8e9a0b1dc437b7a54cc0d3052664f117a96034fe 100644 (file)
--- a/drivers/hwmon/lm80.c
+++ b/drivers/hwmon/lm80.c
@@ -86,18 +86,7 @@ static inline unsigned char FAN_TO_REG(unsigned rpm, unsigned div)
 #define FAN_FROM_REG(val, div) ((val) == 0 ? -1 : \
                                (val) == 255 ? 0 : 1350000/((div) * (val)))
 
-static inline long TEMP_FROM_REG(u16 temp)
-{
-       long res;
-
-       temp >>= 4;
-       if (temp < 0x0800)
-               res = 625 * (long) temp;
-       else
-               res = ((long) temp - 0x01000) * 625;
-
-       return res / 10;
-}
+#define TEMP_FROM_REG(temp) ((temp) * 125 / 32)
 
 #define TEMP_LIMIT_FROM_REG(val)       (((val) > 0x80 ? \
        (val) - 0x100 : (val)) * 1000)
@@ -124,7 +113,7 @@ struct lm80_data {
        u8 fan[2];              /* Register value */
        u8 fan_min[2];          /* Register value */
        u8 fan_div[2];          /* Register encoding, shifted right */
-       u16 temp;               /* Register values, shifted right */
+       s16 temp;               /* Register values */
        u8 temp_hot_max;        /* Register value */
        u8 temp_hot_hyst;       /* Register value */
        u8 temp_os_max;         /* Register value */
@@ -309,7 +298,7 @@ static ssize_t show_temp_input1(struct device *dev,
        struct lm80_data *data = lm80_update_device(dev);
        if (IS_ERR(data))
                return PTR_ERR(data);
-       return sprintf(buf, "%ld\n", TEMP_FROM_REG(data->temp));
+       return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp));
 }
 
 #define show_temp(suffix, value) \