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hwmon: (ltc2990) Fix incorrect conversion of negative temperatures 

Fix incorrect conversion of negative temperatures by using
sign_extend32() instead of a home-grown conversion function.

Fixes: df92270357 ("hwmon: Add LTC2990 sensor driver")
Signed-off-by: Tom Levens <tom.levens@cern.ch>
[groeck: Updated subject and description]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Tom Levens 2017-07-03 06:28:58 +02:00 committed by Guenter Roeck
parent 59df4f4e8e
commit a6282d1703
1 changed files with 4 additions and 14 deletions
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18
drivers/hwmon/ltc2990.c
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@ -11,6 +11,7 @@
* the chip's internal temperature and Vcc power supply voltage.
*/
#include <linux/bitops.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
@ -34,15 +35,6 @@
#define LTC2990_CONTROL_MODE_CURRENT 0x06
#define LTC2990_CONTROL_MODE_VOLTAGE 0x07
/* convert raw register value to sign-extended integer in 16-bit range */
static int ltc2990_voltage_to_int(int raw)
{
if (raw & BIT(14))
return -(0x4000 - (raw & 0x3FFF)) << 2;
else
return (raw & 0x3FFF) << 2;
}
/* Return the converted value from the given register in uV or mC */
static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
{
@ -55,18 +47,16 @@ static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
switch (reg) {
case LTC2990_TINT_MSB:
/* internal temp, 0.0625 degrees/LSB, 13-bit */
val = (val & 0x1FFF) << 3;
*result = (val * 1000) >> 7;
*result = sign_extend32(val, 12) * 1000 / 16;
break;
case LTC2990_V1_MSB:
case LTC2990_V3_MSB:
/* Vx-Vy, 19.42uV/LSB. Depends on mode. */
*result = ltc2990_voltage_to_int(val) * 1942 / (4 * 100);
*result = sign_extend32(val, 14) * 1942 / 100;
break;
case LTC2990_VCC_MSB:
/* Vcc, 305.18μV/LSB, 2.5V offset */
*result = (ltc2990_voltage_to_int(val) * 30518 /
(4 * 100 * 1000)) + 2500;
*result = sign_extend32(val, 14) * 30518 / (100 * 1000) + 2500;
break;
default:
return -EINVAL; /* won't happen, keep compiler happy */