601 lines
15 KiB
C
601 lines
15 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* IIO rescale driver
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*
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* Copyright (C) 2018 Axentia Technologies AB
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* Copyright (C) 2022 Liam Beguin <liambeguin@gmail.com>
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*
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* Author: Peter Rosin <peda@axentia.se>
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*/
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#include <linux/err.h>
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#include <linux/gcd.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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#include <linux/iio/afe/rescale.h>
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#include <linux/iio/consumer.h>
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#include <linux/iio/iio.h>
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int rescale_process_scale(struct rescale *rescale, int scale_type,
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int *val, int *val2)
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{
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s64 tmp;
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int _val, _val2;
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s32 rem, rem2;
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u32 mult;
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u32 neg;
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switch (scale_type) {
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case IIO_VAL_INT:
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*val *= rescale->numerator;
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if (rescale->denominator == 1)
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return scale_type;
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*val2 = rescale->denominator;
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return IIO_VAL_FRACTIONAL;
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case IIO_VAL_FRACTIONAL:
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/*
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* When the product of both scales doesn't overflow, avoid
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* potential accuracy loss (for in kernel consumers) by
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* keeping a fractional representation.
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*/
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if (!check_mul_overflow(*val, rescale->numerator, &_val) &&
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!check_mul_overflow(*val2, rescale->denominator, &_val2)) {
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*val = _val;
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*val2 = _val2;
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return IIO_VAL_FRACTIONAL;
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}
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fallthrough;
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case IIO_VAL_FRACTIONAL_LOG2:
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tmp = (s64)*val * 1000000000LL;
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tmp = div_s64(tmp, rescale->denominator);
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tmp *= rescale->numerator;
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tmp = div_s64_rem(tmp, 1000000000LL, &rem);
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*val = tmp;
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if (!rem)
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return scale_type;
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if (scale_type == IIO_VAL_FRACTIONAL)
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tmp = *val2;
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else
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tmp = ULL(1) << *val2;
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rem2 = *val % (int)tmp;
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*val = *val / (int)tmp;
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*val2 = rem / (int)tmp;
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if (rem2)
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*val2 += div_s64((s64)rem2 * 1000000000LL, tmp);
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return IIO_VAL_INT_PLUS_NANO;
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case IIO_VAL_INT_PLUS_NANO:
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case IIO_VAL_INT_PLUS_MICRO:
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mult = scale_type == IIO_VAL_INT_PLUS_NANO ? 1000000000L : 1000000L;
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/*
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* For IIO_VAL_INT_PLUS_{MICRO,NANO} scale types if either *val
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* OR *val2 is negative the schan scale is negative, i.e.
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* *val = 1 and *val2 = -0.5 yields -1.5 not -0.5.
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*/
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neg = *val < 0 || *val2 < 0;
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tmp = (s64)abs(*val) * abs(rescale->numerator);
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*val = div_s64_rem(tmp, abs(rescale->denominator), &rem);
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tmp = (s64)rem * mult + (s64)abs(*val2) * abs(rescale->numerator);
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tmp = div_s64(tmp, abs(rescale->denominator));
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*val += div_s64_rem(tmp, mult, val2);
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/*
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* If only one of the rescaler elements or the schan scale is
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* negative, the combined scale is negative.
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*/
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if (neg ^ ((rescale->numerator < 0) ^ (rescale->denominator < 0))) {
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if (*val)
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*val = -*val;
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else
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*val2 = -*val2;
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}
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return scale_type;
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default:
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return -EOPNOTSUPP;
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}
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}
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EXPORT_SYMBOL_NS_GPL(rescale_process_scale, IIO_RESCALE);
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int rescale_process_offset(struct rescale *rescale, int scale_type,
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int scale, int scale2, int schan_off,
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int *val, int *val2)
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{
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s64 tmp, tmp2;
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switch (scale_type) {
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case IIO_VAL_FRACTIONAL:
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tmp = (s64)rescale->offset * scale2;
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*val = div_s64(tmp, scale) + schan_off;
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return IIO_VAL_INT;
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case IIO_VAL_INT:
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*val = div_s64(rescale->offset, scale) + schan_off;
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return IIO_VAL_INT;
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case IIO_VAL_FRACTIONAL_LOG2:
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tmp = (s64)rescale->offset * (1 << scale2);
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*val = div_s64(tmp, scale) + schan_off;
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return IIO_VAL_INT;
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case IIO_VAL_INT_PLUS_NANO:
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tmp = (s64)rescale->offset * 1000000000LL;
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tmp2 = ((s64)scale * 1000000000LL) + scale2;
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*val = div64_s64(tmp, tmp2) + schan_off;
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return IIO_VAL_INT;
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case IIO_VAL_INT_PLUS_MICRO:
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tmp = (s64)rescale->offset * 1000000LL;
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tmp2 = ((s64)scale * 1000000LL) + scale2;
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*val = div64_s64(tmp, tmp2) + schan_off;
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return IIO_VAL_INT;
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default:
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return -EOPNOTSUPP;
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}
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}
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EXPORT_SYMBOL_NS_GPL(rescale_process_offset, IIO_RESCALE);
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static int rescale_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long mask)
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{
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struct rescale *rescale = iio_priv(indio_dev);
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int scale, scale2;
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int schan_off = 0;
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int ret;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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if (rescale->chan_processed)
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/*
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* When only processed channels are supported, we
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* read the processed data and scale it by 1/1
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* augmented with whatever the rescaler has calculated.
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*/
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return iio_read_channel_processed(rescale->source, val);
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else
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return iio_read_channel_raw(rescale->source, val);
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case IIO_CHAN_INFO_SCALE:
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if (rescale->chan_processed) {
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/*
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* Processed channels are scaled 1-to-1
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*/
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*val = 1;
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*val2 = 1;
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ret = IIO_VAL_FRACTIONAL;
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} else {
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ret = iio_read_channel_scale(rescale->source, val, val2);
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}
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return rescale_process_scale(rescale, ret, val, val2);
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case IIO_CHAN_INFO_OFFSET:
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/*
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* Processed channels are scaled 1-to-1 and source offset is
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* already taken into account.
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*
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* In other cases, real world measurement are expressed as:
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*
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* schan_scale * (raw + schan_offset)
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*
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* Given that the rescaler parameters are applied recursively:
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*
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* rescaler_scale * (schan_scale * (raw + schan_offset) +
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* rescaler_offset)
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*
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* Or,
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*
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* (rescaler_scale * schan_scale) * (raw +
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* (schan_offset + rescaler_offset / schan_scale)
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*
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* Thus, reusing the original expression the parameters exposed
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* to userspace are:
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*
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* scale = schan_scale * rescaler_scale
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* offset = schan_offset + rescaler_offset / schan_scale
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*/
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if (rescale->chan_processed) {
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*val = rescale->offset;
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return IIO_VAL_INT;
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}
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if (iio_channel_has_info(rescale->source->channel,
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IIO_CHAN_INFO_OFFSET)) {
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ret = iio_read_channel_offset(rescale->source,
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&schan_off, NULL);
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if (ret != IIO_VAL_INT)
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return ret < 0 ? ret : -EOPNOTSUPP;
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}
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ret = iio_read_channel_scale(rescale->source, &scale, &scale2);
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return rescale_process_offset(rescale, ret, scale, scale2,
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schan_off, val, val2);
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default:
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return -EINVAL;
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}
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}
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static int rescale_read_avail(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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const int **vals, int *type, int *length,
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long mask)
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{
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struct rescale *rescale = iio_priv(indio_dev);
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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*type = IIO_VAL_INT;
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return iio_read_avail_channel_raw(rescale->source,
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vals, length);
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default:
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return -EINVAL;
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}
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}
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static const struct iio_info rescale_info = {
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.read_raw = rescale_read_raw,
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.read_avail = rescale_read_avail,
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};
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static ssize_t rescale_read_ext_info(struct iio_dev *indio_dev,
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uintptr_t private,
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struct iio_chan_spec const *chan,
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char *buf)
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{
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struct rescale *rescale = iio_priv(indio_dev);
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return iio_read_channel_ext_info(rescale->source,
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rescale->ext_info[private].name,
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buf);
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}
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static ssize_t rescale_write_ext_info(struct iio_dev *indio_dev,
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uintptr_t private,
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struct iio_chan_spec const *chan,
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const char *buf, size_t len)
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{
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struct rescale *rescale = iio_priv(indio_dev);
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return iio_write_channel_ext_info(rescale->source,
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rescale->ext_info[private].name,
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buf, len);
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}
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static int rescale_configure_channel(struct device *dev,
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struct rescale *rescale)
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{
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struct iio_chan_spec *chan = &rescale->chan;
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struct iio_chan_spec const *schan = rescale->source->channel;
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chan->indexed = 1;
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chan->output = schan->output;
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chan->ext_info = rescale->ext_info;
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chan->type = rescale->cfg->type;
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if (iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) &&
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iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE)) {
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dev_info(dev, "using raw+scale source channel\n");
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} else if (iio_channel_has_info(schan, IIO_CHAN_INFO_PROCESSED)) {
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dev_info(dev, "using processed channel\n");
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rescale->chan_processed = true;
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} else {
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dev_err(dev, "source channel is not supported\n");
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return -EINVAL;
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}
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chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
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BIT(IIO_CHAN_INFO_SCALE);
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if (rescale->offset)
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chan->info_mask_separate |= BIT(IIO_CHAN_INFO_OFFSET);
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/*
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* Using .read_avail() is fringe to begin with and makes no sense
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* whatsoever for processed channels, so we make sure that this cannot
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* be called on a processed channel.
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*/
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if (iio_channel_has_available(schan, IIO_CHAN_INFO_RAW) &&
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!rescale->chan_processed)
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chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW);
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return 0;
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}
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static int rescale_current_sense_amplifier_props(struct device *dev,
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struct rescale *rescale)
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{
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u32 sense;
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u32 gain_mult = 1;
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u32 gain_div = 1;
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u32 factor;
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int ret;
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ret = device_property_read_u32(dev, "sense-resistor-micro-ohms",
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&sense);
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if (ret) {
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dev_err(dev, "failed to read the sense resistance: %d\n", ret);
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return ret;
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}
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device_property_read_u32(dev, "sense-gain-mult", &gain_mult);
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device_property_read_u32(dev, "sense-gain-div", &gain_div);
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/*
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* Calculate the scaling factor, 1 / (gain * sense), or
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* gain_div / (gain_mult * sense), while trying to keep the
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* numerator/denominator from overflowing.
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*/
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factor = gcd(sense, 1000000);
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rescale->numerator = 1000000 / factor;
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rescale->denominator = sense / factor;
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factor = gcd(rescale->numerator, gain_mult);
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rescale->numerator /= factor;
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rescale->denominator *= gain_mult / factor;
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factor = gcd(rescale->denominator, gain_div);
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rescale->numerator *= gain_div / factor;
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rescale->denominator /= factor;
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return 0;
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}
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static int rescale_current_sense_shunt_props(struct device *dev,
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struct rescale *rescale)
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{
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u32 shunt;
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u32 factor;
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int ret;
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ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms",
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&shunt);
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if (ret) {
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dev_err(dev, "failed to read the shunt resistance: %d\n", ret);
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return ret;
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}
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factor = gcd(shunt, 1000000);
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rescale->numerator = 1000000 / factor;
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rescale->denominator = shunt / factor;
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int rescale_voltage_divider_props(struct device *dev,
|
||
|
|
struct rescale *rescale)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
u32 factor;
|
||
|
|
|
||
|
|
ret = device_property_read_u32(dev, "output-ohms",
|
||
|
|
&rescale->denominator);
|
||
|
|
if (ret) {
|
||
|
|
dev_err(dev, "failed to read output-ohms: %d\n", ret);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
ret = device_property_read_u32(dev, "full-ohms",
|
||
|
|
&rescale->numerator);
|
||
|
|
if (ret) {
|
||
|
|
dev_err(dev, "failed to read full-ohms: %d\n", ret);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
factor = gcd(rescale->numerator, rescale->denominator);
|
||
|
|
rescale->numerator /= factor;
|
||
|
|
rescale->denominator /= factor;
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int rescale_temp_sense_rtd_props(struct device *dev,
|
||
|
|
struct rescale *rescale)
|
||
|
|
{
|
||
|
|
u32 factor;
|
||
|
|
u32 alpha;
|
||
|
|
u32 iexc;
|
||
|
|
u32 tmp;
|
||
|
|
int ret;
|
||
|
|
u32 r0;
|
||
|
|
|
||
|
|
ret = device_property_read_u32(dev, "excitation-current-microamp",
|
||
|
|
&iexc);
|
||
|
|
if (ret) {
|
||
|
|
dev_err(dev, "failed to read excitation-current-microamp: %d\n",
|
||
|
|
ret);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
ret = device_property_read_u32(dev, "alpha-ppm-per-celsius", &alpha);
|
||
|
|
if (ret) {
|
||
|
|
dev_err(dev, "failed to read alpha-ppm-per-celsius: %d\n",
|
||
|
|
ret);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
ret = device_property_read_u32(dev, "r-naught-ohms", &r0);
|
||
|
|
if (ret) {
|
||
|
|
dev_err(dev, "failed to read r-naught-ohms: %d\n", ret);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
tmp = r0 * iexc * alpha / 1000000;
|
||
|
|
factor = gcd(tmp, 1000000);
|
||
|
|
rescale->numerator = 1000000 / factor;
|
||
|
|
rescale->denominator = tmp / factor;
|
||
|
|
|
||
|
|
rescale->offset = -1 * ((r0 * iexc) / 1000);
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int rescale_temp_transducer_props(struct device *dev,
|
||
|
|
struct rescale *rescale)
|
||
|
|
{
|
||
|
|
s32 offset = 0;
|
||
|
|
s32 sense = 1;
|
||
|
|
s32 alpha;
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
device_property_read_u32(dev, "sense-offset-millicelsius", &offset);
|
||
|
|
device_property_read_u32(dev, "sense-resistor-ohms", &sense);
|
||
|
|
ret = device_property_read_u32(dev, "alpha-ppm-per-celsius", &alpha);
|
||
|
|
if (ret) {
|
||
|
|
dev_err(dev, "failed to read alpha-ppm-per-celsius: %d\n", ret);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
rescale->numerator = 1000000;
|
||
|
|
rescale->denominator = alpha * sense;
|
||
|
|
|
||
|
|
rescale->offset = div_s64((s64)offset * rescale->denominator,
|
||
|
|
rescale->numerator);
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
enum rescale_variant {
|
||
|
|
CURRENT_SENSE_AMPLIFIER,
|
||
|
|
CURRENT_SENSE_SHUNT,
|
||
|
|
VOLTAGE_DIVIDER,
|
||
|
|
TEMP_SENSE_RTD,
|
||
|
|
TEMP_TRANSDUCER,
|
||
|
|
};
|
||
|
|
|
||
|
|
static const struct rescale_cfg rescale_cfg[] = {
|
||
|
|
[CURRENT_SENSE_AMPLIFIER] = {
|
||
|
|
.type = IIO_CURRENT,
|
||
|
|
.props = rescale_current_sense_amplifier_props,
|
||
|
|
},
|
||
|
|
[CURRENT_SENSE_SHUNT] = {
|
||
|
|
.type = IIO_CURRENT,
|
||
|
|
.props = rescale_current_sense_shunt_props,
|
||
|
|
},
|
||
|
|
[VOLTAGE_DIVIDER] = {
|
||
|
|
.type = IIO_VOLTAGE,
|
||
|
|
.props = rescale_voltage_divider_props,
|
||
|
|
},
|
||
|
|
[TEMP_SENSE_RTD] = {
|
||
|
|
.type = IIO_TEMP,
|
||
|
|
.props = rescale_temp_sense_rtd_props,
|
||
|
|
},
|
||
|
|
[TEMP_TRANSDUCER] = {
|
||
|
|
.type = IIO_TEMP,
|
||
|
|
.props = rescale_temp_transducer_props,
|
||
|
|
},
|
||
|
|
};
|
||
|
|
|
||
|
|
static const struct of_device_id rescale_match[] = {
|
||
|
|
{ .compatible = "current-sense-amplifier",
|
||
|
|
.data = &rescale_cfg[CURRENT_SENSE_AMPLIFIER], },
|
||
|
|
{ .compatible = "current-sense-shunt",
|
||
|
|
.data = &rescale_cfg[CURRENT_SENSE_SHUNT], },
|
||
|
|
{ .compatible = "voltage-divider",
|
||
|
|
.data = &rescale_cfg[VOLTAGE_DIVIDER], },
|
||
|
|
{ .compatible = "temperature-sense-rtd",
|
||
|
|
.data = &rescale_cfg[TEMP_SENSE_RTD], },
|
||
|
|
{ .compatible = "temperature-transducer",
|
||
|
|
.data = &rescale_cfg[TEMP_TRANSDUCER], },
|
||
|
|
{ /* sentinel */ }
|
||
|
|
};
|
||
|
|
MODULE_DEVICE_TABLE(of, rescale_match);
|
||
|
|
|
||
|
|
static int rescale_probe(struct platform_device *pdev)
|
||
|
|
{
|
||
|
|
struct device *dev = &pdev->dev;
|
||
|
|
struct iio_dev *indio_dev;
|
||
|
|
struct iio_channel *source;
|
||
|
|
struct rescale *rescale;
|
||
|
|
int sizeof_ext_info;
|
||
|
|
int sizeof_priv;
|
||
|
|
int i;
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
source = devm_iio_channel_get(dev, NULL);
|
||
|
|
if (IS_ERR(source))
|
||
|
|
return dev_err_probe(dev, PTR_ERR(source),
|
||
|
|
"failed to get source channel\n");
|
||
|
|
|
||
|
|
sizeof_ext_info = iio_get_channel_ext_info_count(source);
|
||
|
|
if (sizeof_ext_info) {
|
||
|
|
sizeof_ext_info += 1; /* one extra entry for the sentinel */
|
||
|
|
sizeof_ext_info *= sizeof(*rescale->ext_info);
|
||
|
|
}
|
||
|
|
|
||
|
|
sizeof_priv = sizeof(*rescale) + sizeof_ext_info;
|
||
|
|
|
||
|
|
indio_dev = devm_iio_device_alloc(dev, sizeof_priv);
|
||
|
|
if (!indio_dev)
|
||
|
|
return -ENOMEM;
|
||
|
|
|
||
|
|
rescale = iio_priv(indio_dev);
|
||
|
|
|
||
|
|
rescale->cfg = device_get_match_data(dev);
|
||
|
|
rescale->numerator = 1;
|
||
|
|
rescale->denominator = 1;
|
||
|
|
rescale->offset = 0;
|
||
|
|
|
||
|
|
ret = rescale->cfg->props(dev, rescale);
|
||
|
|
if (ret)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
if (!rescale->numerator || !rescale->denominator) {
|
||
|
|
dev_err(dev, "invalid scaling factor.\n");
|
||
|
|
return -EINVAL;
|
||
|
|
}
|
||
|
|
|
||
|
|
platform_set_drvdata(pdev, indio_dev);
|
||
|
|
|
||
|
|
rescale->source = source;
|
||
|
|
|
||
|
|
indio_dev->name = dev_name(dev);
|
||
|
|
indio_dev->info = &rescale_info;
|
||
|
|
indio_dev->modes = INDIO_DIRECT_MODE;
|
||
|
|
indio_dev->channels = &rescale->chan;
|
||
|
|
indio_dev->num_channels = 1;
|
||
|
|
if (sizeof_ext_info) {
|
||
|
|
rescale->ext_info = devm_kmemdup(dev,
|
||
|
|
source->channel->ext_info,
|
||
|
|
sizeof_ext_info, GFP_KERNEL);
|
||
|
|
if (!rescale->ext_info)
|
||
|
|
return -ENOMEM;
|
||
|
|
|
||
|
|
for (i = 0; rescale->ext_info[i].name; ++i) {
|
||
|
|
struct iio_chan_spec_ext_info *ext_info =
|
||
|
|
&rescale->ext_info[i];
|
||
|
|
|
||
|
|
if (source->channel->ext_info[i].read)
|
||
|
|
ext_info->read = rescale_read_ext_info;
|
||
|
|
if (source->channel->ext_info[i].write)
|
||
|
|
ext_info->write = rescale_write_ext_info;
|
||
|
|
ext_info->private = i;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
ret = rescale_configure_channel(dev, rescale);
|
||
|
|
if (ret)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
return devm_iio_device_register(dev, indio_dev);
|
||
|
|
}
|
||
|
|
|
||
|
|
static struct platform_driver rescale_driver = {
|
||
|
|
.probe = rescale_probe,
|
||
|
|
.driver = {
|
||
|
|
.name = "iio-rescale",
|
||
|
|
.of_match_table = rescale_match,
|
||
|
|
},
|
||
|
|
};
|
||
|
|
module_platform_driver(rescale_driver);
|
||
|
|
|
||
|
|
MODULE_DESCRIPTION("IIO rescale driver");
|
||
|
|
MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
|
||
|
|
MODULE_LICENSE("GPL v2");
|