| Message ID | 20210701010034.303088-7-liambeguin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | iio: afe: add temperature rescaling support | expand |
On Wed, 30 Jun 2021 21:00:30 -0400 Liam Beguin <liambeguin@gmail.com> wrote: > From: Liam Beguin <lvb@xiphos.com> > > This is a preparatory change required for the addition of temperature > sensing front ends. > > Signed-off-by: Liam Beguin <lvb@xiphos.com> Hi Liam. A few remaining things inline. Looking good in general. Jonathan > --- > drivers/iio/afe/iio-rescale.c | 63 +++++++++++++++++++++++++++++++++++ > 1 file changed, 63 insertions(+) > > diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c > index 8f79c582519c..c8750286c308 100644 > --- a/drivers/iio/afe/iio-rescale.c > +++ b/drivers/iio/afe/iio-rescale.c > @@ -32,6 +32,7 @@ struct rescale { > bool chan_processed; > s32 numerator; > s32 denominator; > + s32 offset; > }; > > static int rescale_read_raw(struct iio_dev *indio_dev, > @@ -39,6 +40,8 @@ static int rescale_read_raw(struct iio_dev *indio_dev, > int *val, int *val2, long mask) > { > struct rescale *rescale = iio_priv(indio_dev); > + int scale, scale2; > + int schan_off = 0; > s64 tmp, tmp2; > u32 factor; > int ret; > @@ -99,6 +102,62 @@ static int rescale_read_raw(struct iio_dev *indio_dev, > dev_err(&indio_dev->dev, "unsupported type %d\n", ret); > return -EOPNOTSUPP; > } > + case IIO_CHAN_INFO_OFFSET: > + /* > + * Processed channels are scaled 1-to-1 and source offset is > + * already taken into account. > + * > + * In other cases, the final offset value is defined by: > + * offset = schan_offset + rescaler_offset / schan_scale Maths is right, but perhaps useful to express how this is derived as I had to scribble it down to check. Want to express real world measurement as: scale * (raw + offset) Given we applying scale and offset recursively we have. rescaler_scale * (schan_scale * (raw + schan_offset) + rescaler_offset) which can be rearrange into the correct form at. rescaler_scale *schan_scale* (raw + (schan_offset + rescaler_offset/schan_scale)) Thus the scale and offset we expose to userspace should be. scale = rescaler_scale * schan_scale offset = schan_offset + rescaler_offset/schan_scale; > + */ > + if (rescale->chan_processed) { > + *val = rescale->offset; > + return IIO_VAL_INT; > + } > + > + if (iio_channel_has_info(rescale->source->channel, > + IIO_CHAN_INFO_OFFSET)) { > + ret = iio_read_channel_offset(rescale->source, > + &schan_off, NULL); > + if (ret < 0) > + return ret; if you've returned in the first branch of the if, no need to worry about the else for checking the second condition. if (ret != IIO_VAL_INT) return... > + else if (ret != IIO_VAL_INT) > + return -EOPNOTSUPP; > + } > + > + ret = iio_read_channel_scale(rescale->source, &scale, &scale2); > + switch (ret) { > + case IIO_VAL_FRACTIONAL: > + tmp = (s64)rescale->offset * scale2; > + *val = div_s64(tmp, scale) + schan_off; > + return IIO_VAL_INT; > + case IIO_VAL_INT: > + *val = div_s64(rescale->offset, scale) + schan_off; > + return IIO_VAL_INT; > + case IIO_VAL_FRACTIONAL_LOG2: > + tmp = (s64)rescale->offset * (1 << scale2); > + *val = div_s64(tmp, scale) + schan_off; > + return IIO_VAL_INT; > + case IIO_VAL_INT_PLUS_NANO: > + tmp = (s64)rescale->offset * 1000000000UL; > + tmp2 = ((s64)scale * 1000000000UL) + scale2; > + factor = gcd(tmp, tmp2); > + tmp /= factor; > + tmp2 /= factor; What is the benefit to doing gcd division before div_s64? > + *val = div_s64(tmp, tmp2) + schan_off; > + return IIO_VAL_INT; > + case IIO_VAL_INT_PLUS_MICRO: > + tmp = (s64)rescale->offset * 1000000UL; > + tmp2 = ((s64)scale * 1000000UL) + scale2; > + factor = gcd(tmp, tmp2); > + tmp /= factor; > + tmp2 /= factor; > + *val = div_s64(tmp, tmp2) + schan_off; > + return IIO_VAL_INT; > + default: > + dev_err(&indio_dev->dev, "unsupported type %d\n", ret); > + return -EOPNOTSUPP; > + } > default: > return -EINVAL; > } > @@ -175,6 +234,9 @@ static int rescale_configure_channel(struct device *dev, > chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | > BIT(IIO_CHAN_INFO_SCALE); > > + if (rescale->offset) > + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_OFFSET); > + > /* > * Using .read_avail() is fringe to begin with and makes no sense > * whatsoever for processed channels, so we make sure that this cannot > @@ -339,6 +401,7 @@ static int rescale_probe(struct platform_device *pdev) > rescale->cfg = of_device_get_match_data(dev); > rescale->numerator = 1; > rescale->denominator = 1; > + rescale->offset = 0; > > ret = rescale->cfg->props(dev, rescale); > if (ret)
On Sun Jul 4, 2021 at 12:53 PM EDT, Jonathan Cameron wrote: > On Wed, 30 Jun 2021 21:00:30 -0400 > Liam Beguin <liambeguin@gmail.com> wrote: > > > From: Liam Beguin <lvb@xiphos.com> > > > > This is a preparatory change required for the addition of temperature > > sensing front ends. > > > > Signed-off-by: Liam Beguin <lvb@xiphos.com> > Hi Liam. > > A few remaining things inline. > > Looking good in general. > > Jonathan > > > --- > > drivers/iio/afe/iio-rescale.c | 63 +++++++++++++++++++++++++++++++++++ > > 1 file changed, 63 insertions(+) > > > > diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c > > index 8f79c582519c..c8750286c308 100644 > > --- a/drivers/iio/afe/iio-rescale.c > > +++ b/drivers/iio/afe/iio-rescale.c > > @@ -32,6 +32,7 @@ struct rescale { > > bool chan_processed; > > s32 numerator; > > s32 denominator; > > + s32 offset; > > }; > > > > static int rescale_read_raw(struct iio_dev *indio_dev, > > @@ -39,6 +40,8 @@ static int rescale_read_raw(struct iio_dev *indio_dev, > > int *val, int *val2, long mask) > > { > > struct rescale *rescale = iio_priv(indio_dev); > > + int scale, scale2; > > + int schan_off = 0; > > s64 tmp, tmp2; > > u32 factor; > > int ret; > > @@ -99,6 +102,62 @@ static int rescale_read_raw(struct iio_dev *indio_dev, > > dev_err(&indio_dev->dev, "unsupported type %d\n", ret); > > return -EOPNOTSUPP; > > } > > + case IIO_CHAN_INFO_OFFSET: > > + /* > > + * Processed channels are scaled 1-to-1 and source offset is > > + * already taken into account. > > + * > > + * In other cases, the final offset value is defined by: > > + * offset = schan_offset + rescaler_offset / schan_scale > > Maths is right, but perhaps useful to express how this is derived as I > had > to scribble it down to check. > > Want to express real world measurement as: > scale * (raw + offset) > Given we applying scale and offset recursively we have. > rescaler_scale * (schan_scale * (raw + schan_offset) + rescaler_offset) > which can be rearrange into the correct form at. > rescaler_scale *schan_scale* (raw + (schan_offset + > rescaler_offset/schan_scale)) > Thus the scale and offset we expose to userspace should be. > scale = rescaler_scale * schan_scale > offset = schan_offset + rescaler_offset/schan_scale; > Understood, I'll update the comment with more details. > > > + */ > > + if (rescale->chan_processed) { > > + *val = rescale->offset; > > + return IIO_VAL_INT; > > + } > > + > > + if (iio_channel_has_info(rescale->source->channel, > > + IIO_CHAN_INFO_OFFSET)) { > > + ret = iio_read_channel_offset(rescale->source, > > + &schan_off, NULL); > > + if (ret < 0) > > + return ret; > if you've returned in the first branch of the if, no need to worry about > the > else for checking the second condition. > > if (ret != IIO_VAL_INT) > return... Right, I'll combine both statements. > > > > + else if (ret != IIO_VAL_INT) > > + return -EOPNOTSUPP; > > + } > > + > > + ret = iio_read_channel_scale(rescale->source, &scale, &scale2); > > + switch (ret) { > > + case IIO_VAL_FRACTIONAL: > > + tmp = (s64)rescale->offset * scale2; > > + *val = div_s64(tmp, scale) + schan_off; > > + return IIO_VAL_INT; > > + case IIO_VAL_INT: > > + *val = div_s64(rescale->offset, scale) + schan_off; > > + return IIO_VAL_INT; > > + case IIO_VAL_FRACTIONAL_LOG2: > > + tmp = (s64)rescale->offset * (1 << scale2); > > + *val = div_s64(tmp, scale) + schan_off; > > + return IIO_VAL_INT; > > + case IIO_VAL_INT_PLUS_NANO: > > + tmp = (s64)rescale->offset * 1000000000UL; > > + tmp2 = ((s64)scale * 1000000000UL) + scale2; > > + factor = gcd(tmp, tmp2); > > + tmp /= factor; > > + tmp2 /= factor; > > What is the benefit to doing gcd division before div_s64? > You're right the GCD division is unnecessary here, will drop. > > + *val = div_s64(tmp, tmp2) + schan_off; > > + return IIO_VAL_INT; > > + case IIO_VAL_INT_PLUS_MICRO: > > + tmp = (s64)rescale->offset * 1000000UL; > > + tmp2 = ((s64)scale * 1000000UL) + scale2; > > + factor = gcd(tmp, tmp2); > > + tmp /= factor; > > + tmp2 /= factor; > > + *val = div_s64(tmp, tmp2) + schan_off; > > + return IIO_VAL_INT; > > + default: > > + dev_err(&indio_dev->dev, "unsupported type %d\n", ret); > > + return -EOPNOTSUPP; > > + } > > default: > > return -EINVAL; > > } > > @@ -175,6 +234,9 @@ static int rescale_configure_channel(struct device *dev, > > chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | > > BIT(IIO_CHAN_INFO_SCALE); > > > > + if (rescale->offset) > > + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_OFFSET); > > + > > /* > > * Using .read_avail() is fringe to begin with and makes no sense > > * whatsoever for processed channels, so we make sure that this cannot > > @@ -339,6 +401,7 @@ static int rescale_probe(struct platform_device *pdev) > > rescale->cfg = of_device_get_match_data(dev); > > rescale->numerator = 1; > > rescale->denominator = 1; > > + rescale->offset = 0; > > > > ret = rescale->cfg->props(dev, rescale); > > if (ret)
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c index 8f79c582519c..c8750286c308 100644 --- a/drivers/iio/afe/iio-rescale.c +++ b/drivers/iio/afe/iio-rescale.c @@ -32,6 +32,7 @@ struct rescale { bool chan_processed; s32 numerator; s32 denominator; + s32 offset; }; static int rescale_read_raw(struct iio_dev *indio_dev, @@ -39,6 +40,8 @@ static int rescale_read_raw(struct iio_dev *indio_dev, int *val, int *val2, long mask) { struct rescale *rescale = iio_priv(indio_dev); + int scale, scale2; + int schan_off = 0; s64 tmp, tmp2; u32 factor; int ret; @@ -99,6 +102,62 @@ static int rescale_read_raw(struct iio_dev *indio_dev, dev_err(&indio_dev->dev, "unsupported type %d\n", ret); return -EOPNOTSUPP; } + case IIO_CHAN_INFO_OFFSET: + /* + * Processed channels are scaled 1-to-1 and source offset is + * already taken into account. + * + * In other cases, the final offset value is defined by: + * offset = schan_offset + rescaler_offset / schan_scale + */ + if (rescale->chan_processed) { + *val = rescale->offset; + return IIO_VAL_INT; + } + + if (iio_channel_has_info(rescale->source->channel, + IIO_CHAN_INFO_OFFSET)) { + ret = iio_read_channel_offset(rescale->source, + &schan_off, NULL); + if (ret < 0) + return ret; + else if (ret != IIO_VAL_INT) + return -EOPNOTSUPP; + } + + ret = iio_read_channel_scale(rescale->source, &scale, &scale2); + switch (ret) { + case IIO_VAL_FRACTIONAL: + tmp = (s64)rescale->offset * scale2; + *val = div_s64(tmp, scale) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_INT: + *val = div_s64(rescale->offset, scale) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_FRACTIONAL_LOG2: + tmp = (s64)rescale->offset * (1 << scale2); + *val = div_s64(tmp, scale) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_INT_PLUS_NANO: + tmp = (s64)rescale->offset * 1000000000UL; + tmp2 = ((s64)scale * 1000000000UL) + scale2; + factor = gcd(tmp, tmp2); + tmp /= factor; + tmp2 /= factor; + *val = div_s64(tmp, tmp2) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_INT_PLUS_MICRO: + tmp = (s64)rescale->offset * 1000000UL; + tmp2 = ((s64)scale * 1000000UL) + scale2; + factor = gcd(tmp, tmp2); + tmp /= factor; + tmp2 /= factor; + *val = div_s64(tmp, tmp2) + schan_off; + return IIO_VAL_INT; + default: + dev_err(&indio_dev->dev, "unsupported type %d\n", ret); + return -EOPNOTSUPP; + } default: return -EINVAL; } @@ -175,6 +234,9 @@ static int rescale_configure_channel(struct device *dev, chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE); + if (rescale->offset) + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_OFFSET); + /* * Using .read_avail() is fringe to begin with and makes no sense * whatsoever for processed channels, so we make sure that this cannot @@ -339,6 +401,7 @@ static int rescale_probe(struct platform_device *pdev) rescale->cfg = of_device_get_match_data(dev); rescale->numerator = 1; rescale->denominator = 1; + rescale->offset = 0; ret = rescale->cfg->props(dev, rescale); if (ret)