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![Linus Walleij](/assets/img/avatar_default.png)
It happens that an ADC will only provide raw or processed voltage conversion channels. (adc/ab8500-gpadc.c). On the Samsung GT-I9070 this is used for a light sensor and current sense amplifier so we need to think of something. The idea is to allow processed channels and scale them with 1/1 and then the rescaler can modify the result on top. Link: https://lore.kernel.org/linux-iio/20201101232211.1194304-1-linus.walleij@linaro.org/ Cc: Peter Rosin <peda@axentia.se> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Peter Rosin <peda@axentia.se> Link: https://lore.kernel.org/r/20210518092741.403080-1-linus.walleij@linaro.org Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
385 lines
9.4 KiB
C
385 lines
9.4 KiB
C
// 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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*
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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/iio/consumer.h>
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#include <linux/iio/iio.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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struct rescale;
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struct rescale_cfg {
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enum iio_chan_type type;
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int (*props)(struct device *dev, struct rescale *rescale);
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};
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struct rescale {
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const struct rescale_cfg *cfg;
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struct iio_channel *source;
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struct iio_chan_spec chan;
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struct iio_chan_spec_ext_info *ext_info;
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bool chan_processed;
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s32 numerator;
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s32 denominator;
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};
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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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unsigned long long tmp;
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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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switch (ret) {
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case IIO_VAL_FRACTIONAL:
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*val *= rescale->numerator;
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*val2 *= rescale->denominator;
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return ret;
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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 ret;
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*val2 = rescale->denominator;
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return IIO_VAL_FRACTIONAL;
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case IIO_VAL_FRACTIONAL_LOG2:
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tmp = *val * 1000000000LL;
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do_div(tmp, rescale->denominator);
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tmp *= rescale->numerator;
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do_div(tmp, 1000000000LL);
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*val = tmp;
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return ret;
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default:
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return -EOPNOTSUPP;
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}
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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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/*
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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;
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return 0;
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}
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static int rescale_voltage_divider_props(struct device *dev,
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struct rescale *rescale)
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{
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int ret;
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u32 factor;
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ret = device_property_read_u32(dev, "output-ohms",
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&rescale->denominator);
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if (ret) {
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dev_err(dev, "failed to read output-ohms: %d\n", ret);
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return ret;
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}
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ret = device_property_read_u32(dev, "full-ohms",
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&rescale->numerator);
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if (ret) {
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dev_err(dev, "failed to read full-ohms: %d\n", ret);
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return ret;
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}
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factor = gcd(rescale->numerator, rescale->denominator);
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rescale->numerator /= factor;
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rescale->denominator /= factor;
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return 0;
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}
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enum rescale_variant {
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CURRENT_SENSE_AMPLIFIER,
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CURRENT_SENSE_SHUNT,
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VOLTAGE_DIVIDER,
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};
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static const struct rescale_cfg rescale_cfg[] = {
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[CURRENT_SENSE_AMPLIFIER] = {
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.type = IIO_CURRENT,
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.props = rescale_current_sense_amplifier_props,
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},
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[CURRENT_SENSE_SHUNT] = {
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.type = IIO_CURRENT,
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.props = rescale_current_sense_shunt_props,
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},
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[VOLTAGE_DIVIDER] = {
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.type = IIO_VOLTAGE,
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.props = rescale_voltage_divider_props,
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},
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};
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static const struct of_device_id rescale_match[] = {
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{ .compatible = "current-sense-amplifier",
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.data = &rescale_cfg[CURRENT_SENSE_AMPLIFIER], },
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{ .compatible = "current-sense-shunt",
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.data = &rescale_cfg[CURRENT_SENSE_SHUNT], },
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{ .compatible = "voltage-divider",
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.data = &rescale_cfg[VOLTAGE_DIVIDER], },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, rescale_match);
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static int rescale_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct iio_dev *indio_dev;
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struct iio_channel *source;
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struct rescale *rescale;
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int sizeof_ext_info;
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int sizeof_priv;
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int i;
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int ret;
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source = devm_iio_channel_get(dev, NULL);
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if (IS_ERR(source))
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return dev_err_probe(dev, PTR_ERR(source),
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"failed to get source channel\n");
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sizeof_ext_info = iio_get_channel_ext_info_count(source);
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if (sizeof_ext_info) {
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sizeof_ext_info += 1; /* one extra entry for the sentinel */
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sizeof_ext_info *= sizeof(*rescale->ext_info);
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}
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sizeof_priv = sizeof(*rescale) + sizeof_ext_info;
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indio_dev = devm_iio_device_alloc(dev, sizeof_priv);
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if (!indio_dev)
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return -ENOMEM;
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rescale = iio_priv(indio_dev);
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rescale->cfg = of_device_get_match_data(dev);
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rescale->numerator = 1;
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rescale->denominator = 1;
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ret = rescale->cfg->props(dev, rescale);
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if (ret)
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return ret;
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if (!rescale->numerator || !rescale->denominator) {
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dev_err(dev, "invalid scaling factor.\n");
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return -EINVAL;
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}
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platform_set_drvdata(pdev, indio_dev);
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rescale->source = source;
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indio_dev->name = dev_name(dev);
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indio_dev->info = &rescale_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = &rescale->chan;
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indio_dev->num_channels = 1;
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if (sizeof_ext_info) {
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rescale->ext_info = devm_kmemdup(dev,
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source->channel->ext_info,
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sizeof_ext_info, GFP_KERNEL);
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if (!rescale->ext_info)
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return -ENOMEM;
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for (i = 0; rescale->ext_info[i].name; ++i) {
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struct iio_chan_spec_ext_info *ext_info =
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&rescale->ext_info[i];
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if (source->channel->ext_info[i].read)
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ext_info->read = rescale_read_ext_info;
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if (source->channel->ext_info[i].write)
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ext_info->write = rescale_write_ext_info;
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ext_info->private = i;
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}
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}
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ret = rescale_configure_channel(dev, rescale);
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if (ret)
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return ret;
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return devm_iio_device_register(dev, indio_dev);
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}
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static struct platform_driver rescale_driver = {
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.probe = rescale_probe,
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.driver = {
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.name = "iio-rescale",
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.of_match_table = rescale_match,
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},
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};
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module_platform_driver(rescale_driver);
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MODULE_DESCRIPTION("IIO rescale driver");
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MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
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MODULE_LICENSE("GPL v2");
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