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Subject[PATCH v3 1/3] hwmon: ltc2990: refactor value conversion
Date
Conversion from raw values to signed integers has been refactored using
bitops.h. This also fixes a bug where negative temperatures were
converted incorrectly.

Signed-off-by: Tom Levens <tom.levens@cern.ch>
---
drivers/hwmon/ltc2990.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/drivers/hwmon/ltc2990.c b/drivers/hwmon/ltc2990.c
index 8f8fe05..e320d21 100644
--- a/drivers/hwmon/ltc2990.c
+++ b/drivers/hwmon/ltc2990.c
@@ -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 */
--
1.8.3.1
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