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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>
This commit is contained in:
Guenter Roeck 2014-04-13 09:15:09 -07:00
parent a0ac840d99
commit 9028ff8e3d
1 changed files with 3 additions and 14 deletions
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17
drivers/hwmon/lm80.c
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@ -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) \