Re: [PATCH v9 05/14] iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support
From: Jonathan Cameron <jic23@kernel.org>
Date: 2021-11-21 11:06:41
Also in:
linux-iio, lkml
On Sun, 14 Nov 2021 22:43:25 -0500 Liam Beguin [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: Liam Beguin <redacted> 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 <redacted> --- 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;