diff mbox series

[3/3] hwmon: tmp421: fix rounding for negative values

Message ID 20210922134154.20766-3-fercerpav@gmail.com (mailing list archive)
State Superseded
Headers show
Series [1/3] hwmon: tmp421: handle I2C errors | expand

Commit Message

Paul Fertser Sept. 22, 2021, 1:41 p.m. UTC 
Current code produces -24999 for 0b1110011100000000 input in standard
format due to always rounding up rather than "away from zero". Use the
common macro for division, unify and simplify the conversion code along
the way.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>
---
 drivers/hwmon/tmp421.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)
diff mbox series

Patch

diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
index 9ee4c61531f3..dec3aced3d8b 100644
--- a/drivers/hwmon/tmp421.c
+++ b/drivers/hwmon/tmp421.c
@@ -100,23 +100,17 @@  struct tmp421_data {
 	s16 temp[4];
 };
 
-static int temp_from_s16(s16 reg)
+static int temp_from_raw(u16 reg, bool extended)
 {
 	/* Mask out status bits */
 	int temp = reg & ~0xf;
 
-	return (temp * 1000 + 128) / 256;
-}
-
-static int temp_from_u16(u16 reg)
-{
-	/* Mask out status bits */
-	int temp = reg & ~0xf;
-
-	/* Add offset for extended temperature range. */
-	temp -= 64 * 256;
+	if (extended)
+		temp = temp - 64 * 256;
+	else
+		temp = (s16)temp;
 
-	return (temp * 1000 + 128) / 256;
+	return DIV_ROUND_CLOSEST(temp * 1000, 256);
 }
 
 static struct tmp421_data *tmp421_update_device(struct device *dev)
@@ -167,10 +161,8 @@  static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
 
 	switch (attr) {
 	case hwmon_temp_input:
-		if (tmp421->config & TMP421_CONFIG_RANGE)
-			*val = temp_from_u16(tmp421->temp[channel]);
-		else
-			*val = temp_from_s16(tmp421->temp[channel]);
+		*val = temp_from_raw(tmp421->temp[channel],
+				     tmp421->config & TMP421_CONFIG_RANGE);
 		return 0;
 	case hwmon_temp_fault:
 		/*