mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
staging:iio:ad7793: Fix temperature scale and offset
The temperature channel uses the internal 1.17V reference with 0.81 mv/C. The reported temperature is in Kevlin, so we need to add the Kelvin to Celcius offset when reporting the offset for the temperature channel. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
parent
680f8ea0e8
commit
2a9e0662f6
1 changed files with 18 additions and 11 deletions
|
@ -617,30 +617,37 @@ static int ad7793_read_raw(struct iio_dev *indio_dev,
|
|||
return IIO_VAL_INT_PLUS_NANO;
|
||||
} else {
|
||||
/* 1170mV / 2^23 * 6 */
|
||||
scale_uv = (1170ULL * 100000000ULL * 6ULL)
|
||||
>> (chan->scan_type.realbits -
|
||||
(unipolar ? 0 : 1));
|
||||
scale_uv = (1170ULL * 100000000ULL * 6ULL);
|
||||
}
|
||||
break;
|
||||
case IIO_TEMP:
|
||||
/* Always uses unity gain and internal ref */
|
||||
scale_uv = (2500ULL * 100000000ULL)
|
||||
>> (chan->scan_type.realbits -
|
||||
(unipolar ? 0 : 1));
|
||||
/* 1170mV / 0.81 mV/C / 2^23 */
|
||||
scale_uv = 1444444444444ULL;
|
||||
break;
|
||||
default:
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
*val2 = do_div(scale_uv, 100000000) * 10;
|
||||
*val = scale_uv;
|
||||
|
||||
scale_uv >>= (chan->scan_type.realbits - (unipolar ? 0 : 1));
|
||||
*val = 0;
|
||||
*val2 = scale_uv;
|
||||
return IIO_VAL_INT_PLUS_NANO;
|
||||
case IIO_CHAN_INFO_OFFSET:
|
||||
if (!unipolar)
|
||||
*val -= (1 << (chan->scan_type.realbits - 1));
|
||||
*val = -(1 << (chan->scan_type.realbits - 1));
|
||||
else
|
||||
*val = 0;
|
||||
|
||||
/* Kelvin to Celsius */
|
||||
if (chan->type == IIO_TEMP) {
|
||||
unsigned long long offset;
|
||||
unsigned int shift;
|
||||
|
||||
shift = chan->scan_type.realbits - (unipolar ? 0 : 1);
|
||||
offset = 273ULL << shift;
|
||||
do_div(offset, 1444);
|
||||
*val -= offset;
|
||||
}
|
||||
return IIO_VAL_INT;
|
||||
}
|
||||
return -EINVAL;
|
||||
|
|
Loading…
Reference in a new issue