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iio:ad5764: Report scale as fractional value

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Move the complexity of calculating the fixed point scale to the core.

Also fix a off by one error in the comment describing the transfer function.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Lars-Peter Clausen 2013-09-28 10:31:00 +01:00 committed by Jonathan Cameron
parent ae76751f67
commit 3f83dae884
1 changed files with 4 additions and 6 deletions
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10
drivers/iio/dac/ad5764.c
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@ -217,7 +217,6 @@ static int ad5764_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val, int *val2, long info)
{
struct ad5764_state *st = iio_priv(indio_dev);
unsigned long scale_uv;
unsigned int reg;
int vref;
int ret;
@ -245,15 +244,14 @@ static int ad5764_read_raw(struct iio_dev *indio_dev,
*val = sign_extend32(*val, 5);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
/* vout = 4 * vref + ((dac_code / 65535) - 0.5) */
/* vout = 4 * vref + ((dac_code / 65536) - 0.5) */
vref = ad5764_get_channel_vref(st, chan->channel);
if (vref < 0)
return vref;
scale_uv = (vref * 4 * 100) >> chan->scan_type.realbits;
*val = scale_uv / 100000;
*val2 = (scale_uv % 100000) * 10;
return IIO_VAL_INT_PLUS_MICRO;
*val = vref * 4 / 1000;
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
case IIO_CHAN_INFO_OFFSET:
*val = -(1 << chan->scan_type.realbits) / 2;
return IIO_VAL_INT;