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Commit a6282d17 authored by Tom Levens's avatar Tom Levens Committed by Guenter Roeck
Browse files

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: df922703 ("hwmon: Add LTC2990 sensor driver")
Signed-off-by: default avatarTom Levens <tom.levens@cern.ch>
[groeck: Updated subject and description]
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 59df4f4e

drivers/hwmon/ltc2990.c

+4 −14
Original line number Diff line number Diff line
@@ -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 */