hwmon: (ds1621) Fix temperature rounding operations
Commit "hwmon: (ds1621) Add ds1721 chip support" broke rounding
for chips or configurations with less than 12 bit resolution.
Tested-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/drivers/hwmon/ds1621.c b/drivers/hwmon/ds1621.c
index 591758b..a26ba7a 100644
--- a/drivers/hwmon/ds1621.c
+++ b/drivers/hwmon/ds1621.c
@@ -128,6 +128,8 @@
u16 temp[3]; /* Register values, word */
u8 conf; /* Register encoding, combined */
+ u8 zbits; /* Resolution encoded as number of
+ * zero bits */
u16 update_interval; /* Conversion rate in milliseconds */
};
@@ -139,16 +141,14 @@
/*
* TEMP: 0.001C/bit (-55C to +125C)
* REG:
- * - 1621, 1625: 0.5C/bit
- * - 1631, 1721, 1731: 0.0625C/bit
- * Assume highest resolution and let the bits fall where they may..
+ * - 1621, 1625: 0.5C/bit, 7 zero-bits
+ * - 1631, 1721, 1731: 0.0625C/bit, 4 zero-bits
*/
-static inline u16 DS1621_TEMP_TO_REG(long temp)
+static inline u16 DS1621_TEMP_TO_REG(long temp, u8 zbits)
{
- int ntemp = clamp_val(temp, DS1621_TEMP_MIN, DS1621_TEMP_MAX);
- ntemp += (ntemp < 0 ? -31 : 31);
- ntemp = DIV_ROUND_CLOSEST(ntemp * 10, 625) << 4;
- return (u16)ntemp;
+ temp = clamp_val(temp, DS1621_TEMP_MIN, DS1621_TEMP_MAX);
+ temp = DIV_ROUND_CLOSEST(temp * (1 << (8 - zbits)), 1000) << zbits;
+ return temp;
}
static void ds1621_init_client(struct i2c_client *client)
@@ -172,6 +172,7 @@
switch (data->kind) {
case ds1625:
data->update_interval = DS1625_CONVERSION_MAX;
+ data->zbits = 7;
sreg = DS1621_COM_START;
break;
case ds1631:
@@ -180,10 +181,12 @@
resol = (new_conf & DS1621_REG_CONFIG_RESOL) >>
DS1621_REG_CONFIG_RESOL_SHIFT;
data->update_interval = ds1721_convrates[resol];
+ data->zbits = 7 - resol;
sreg = DS1721_COM_START;
break;
default:
data->update_interval = DS1621_CONVERSION_MAX;
+ data->zbits = 7;
sreg = DS1621_COM_START;
break;
}
@@ -254,7 +257,7 @@
return err;
mutex_lock(&data->update_lock);
- data->temp[attr->index] = DS1621_TEMP_TO_REG(val);
+ data->temp[attr->index] = DS1621_TEMP_TO_REG(val, data->zbits);
i2c_smbus_write_word_swapped(client, DS1621_REG_TEMP[attr->index],
data->temp[attr->index]);
mutex_unlock(&data->update_lock);