| Message ID | 20211115034334.1713050-6-liambeguin@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | iio: afe: add temperature rescaling support | expand |
On Sun, 14 Nov 2021 22:43:25 -0500 Liam Beguin <liambeguin@gmail.com> wrote: > From: Liam Beguin <lvb@xiphos.com> > > Some ADCs use IIO_VAL_INT_PLUS_{NANO,MICRO} scale types. > Add support for these to allow using the iio-rescaler with them. > > Signed-off-by: Liam Beguin <lvb@xiphos.com> > --- > drivers/iio/afe/iio-rescale.c | 36 +++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c > index d0669fd8eac5..2c25a6375f99 100644 > --- a/drivers/iio/afe/iio-rescale.c > +++ b/drivers/iio/afe/iio-rescale.c > @@ -22,6 +22,9 @@ int rescale_process_scale(struct rescale *rescale, int scale_type, > int *val, int *val2) > { > unsigned long long tmp; > + s32 rem; > + u32 mult; > + u32 neg; > > switch (scale_type) { > case IIO_VAL_FRACTIONAL: > @@ -40,6 +43,39 @@ int rescale_process_scale(struct rescale *rescale, int scale_type, > tmp *= rescale->numerator; > do_div(tmp, 1000000000LL); > *val = tmp; > + return scale_type; > + case IIO_VAL_INT_PLUS_NANO: > + case IIO_VAL_INT_PLUS_MICRO: > + if (scale_type == IIO_VAL_INT_PLUS_NANO) > + mult = 1000000000LL; > + else > + mult = 1000000LL; Trivial but perhaps you can use the multipliers defined in include/linux/units.h? mut = MICRO; etc. I think that patch set crossed with the earlier versions of this one but given it's now there I think it would slightly improve readability. > + /* > + * For IIO_VAL_INT_PLUS_{MICRO,NANO} scale types if either *val > + * OR *val2 is negative the schan scale is negative, i.e. > + * *val = 1 and *val2 = -0.5 yields -1.5 not -0.5. > + */ > + neg = *val < 0 || *val2 < 0; > + > + tmp = (s64)abs(*val) * abs(rescale->numerator); > + *val = div_s64_rem(tmp, abs(rescale->denominator), &rem); > + > + tmp = (s64)rem * mult + (s64)abs(*val2) * abs(rescale->numerator); > + tmp = div_s64(tmp, abs(rescale->denominator)); > + > + *val += div_s64_rem(tmp, mult, val2); > + > + /* > + * If only one of the rescaler elements or the schan scale is > + * negative, the combined scale is negative. > + */ > + if (neg ^ ((rescale->numerator < 0) ^ (rescale->denominator < 0))) { > + if (*val) > + *val = -*val; > + else > + *val2 = -*val2; > + } > + > return scale_type; > default: > return -EOPNOTSUPP;
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c index d0669fd8eac5..2c25a6375f99 100644 --- a/drivers/iio/afe/iio-rescale.c +++ b/drivers/iio/afe/iio-rescale.c @@ -22,6 +22,9 @@ int rescale_process_scale(struct rescale *rescale, int scale_type, int *val, int *val2) { unsigned long long tmp; + s32 rem; + u32 mult; + u32 neg; switch (scale_type) { case IIO_VAL_FRACTIONAL: @@ -40,6 +43,39 @@ int rescale_process_scale(struct rescale *rescale, int scale_type, tmp *= rescale->numerator; do_div(tmp, 1000000000LL); *val = tmp; + return scale_type; + case IIO_VAL_INT_PLUS_NANO: + case IIO_VAL_INT_PLUS_MICRO: + if (scale_type == IIO_VAL_INT_PLUS_NANO) + mult = 1000000000LL; + else + mult = 1000000LL; + /* + * For IIO_VAL_INT_PLUS_{MICRO,NANO} scale types if either *val + * OR *val2 is negative the schan scale is negative, i.e. + * *val = 1 and *val2 = -0.5 yields -1.5 not -0.5. + */ + neg = *val < 0 || *val2 < 0; + + tmp = (s64)abs(*val) * abs(rescale->numerator); + *val = div_s64_rem(tmp, abs(rescale->denominator), &rem); + + tmp = (s64)rem * mult + (s64)abs(*val2) * abs(rescale->numerator); + tmp = div_s64(tmp, abs(rescale->denominator)); + + *val += div_s64_rem(tmp, mult, val2); + + /* + * If only one of the rescaler elements or the schan scale is + * negative, the combined scale is negative. + */ + if (neg ^ ((rescale->numerator < 0) ^ (rescale->denominator < 0))) { + if (*val) + *val = -*val; + else + *val2 = -*val2; + } + return scale_type; default: return -EOPNOTSUPP;