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Message-Id: <20220208020441.3081162-4-liambeguin@gmail.com> Date: Mon, 7 Feb 2022 21:04:33 -0500 From: Liam Beguin <liambeguin@...il.com> To: liambeguin@...il.com, peda@...ntia.se, jic23@...nel.org, andy.shevchenko@...il.com, lars@...afoo.de Cc: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org, devicetree@...r.kernel.org, robh+dt@...nel.org Subject: [PATCH v14 03/11] iio: afe: rescale: add offset support This is a preparatory change required for the addition of temperature sensing front ends. Signed-off-by: Liam Beguin <liambeguin@...il.com> Reviewed-by: Peter Rosin <peda@...ntia.se> --- drivers/iio/afe/iio-rescale.c | 81 +++++++++++++++++++++++++++++++++ include/linux/iio/afe/rescale.h | 4 ++ 2 files changed, 85 insertions(+) diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c index f833eb38f8bb..63035b4bce5e 100644 --- a/drivers/iio/afe/iio-rescale.c +++ b/drivers/iio/afe/iio-rescale.c @@ -3,6 +3,7 @@ * IIO rescale driver * * Copyright (C) 2018 Axentia Technologies AB + * Copyright (C) 2022 Liam Beguin <liambeguin@...il.com> * * Author: Peter Rosin <peda@...ntia.se> */ @@ -82,11 +83,46 @@ int rescale_process_scale(struct rescale *rescale, int scale_type, } } +int rescale_process_offset(struct rescale *rescale, int scale_type, + int scale, int scale2, int schan_off, + int *val, int *val2) +{ + s64 tmp, tmp2; + + switch (scale_type) { + 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 * GIGA; + tmp2 = ((s64)scale * GIGA) + scale2; + *val = div64_s64(tmp, tmp2) + schan_off; + return IIO_VAL_INT; + case IIO_VAL_INT_PLUS_MICRO: + tmp = (s64)rescale->offset * MEGA; + tmp2 = ((s64)scale * MEGA) + scale2; + *val = div64_s64(tmp, tmp2) + schan_off; + return IIO_VAL_INT; + default: + return -EOPNOTSUPP; + } +} + static int rescale_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, int *val, int *val2, long mask) { struct rescale *rescale = iio_priv(indio_dev); + int scale, scale2; + int schan_off = 0; int ret; switch (mask) { @@ -113,6 +149,47 @@ static int rescale_read_raw(struct iio_dev *indio_dev, ret = iio_read_channel_scale(rescale->source, val, val2); } return rescale_process_scale(rescale, ret, val, val2); + case IIO_CHAN_INFO_OFFSET: + /* + * Processed channels are scaled 1-to-1 and source offset is + * already taken into account. + * + * In other cases, real world measurement are expressed as: + * + * schan_scale * (raw + schan_offset) + * + * Given that the rescaler parameters are applied recursively: + * + * rescaler_scale * (schan_scale * (raw + schan_offset) + + * rescaler_offset) + * + * Or, + * + * (rescaler_scale * schan_scale) * (raw + + * (schan_offset + rescaler_offset / schan_scale) + * + * Thus, reusing the original expression the parameters exposed + * to userspace are: + * + * scale = schan_scale * rescaler_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 != IIO_VAL_INT) + return ret < 0 ? ret : -EOPNOTSUPP; + } + + ret = iio_read_channel_scale(rescale->source, &scale, &scale2); + return rescale_process_offset(rescale, ret, scale, scale2, + schan_off, val, val2); default: return -EINVAL; } @@ -189,6 +266,9 @@ 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 @@ -353,6 +433,7 @@ 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/include/linux/iio/afe/rescale.h b/include/linux/iio/afe/rescale.h index 8a2eb34af327..6eecb435488f 100644 --- a/include/linux/iio/afe/rescale.h +++ b/include/linux/iio/afe/rescale.h @@ -25,8 +25,12 @@ struct rescale { bool chan_processed; s32 numerator; s32 denominator; + s32 offset; }; int rescale_process_scale(struct rescale *rescale, int scale_type, int *val, int *val2); +int rescale_process_offset(struct rescale *rescale, int scale_type, + int scale, int scale2, int schan_off, + int *val, int *val2); #endif /* __IIO_RESCALE_H__ */ -- 2.35.1.4.g5d01301f2b86
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