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// SPDX-License-Identifier: GPL-2.0
/*
* IIO rescale driver
*
* Copyright (C) 2018 Axentia Technologies AB
*
* Author: Peter Rosin <peda@axentia.se>
*/
#include <linux/err.h>
#include <linux/gcd.h>
#include <linux/iio/consumer.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/property.h>
struct rescale;
struct rescale_cfg {
enum iio_chan_type type;
int (*props)(struct device *dev, struct rescale *rescale);
};
struct rescale {
const struct rescale_cfg *cfg;
struct iio_channel *source;
struct iio_chan_spec chan;
struct iio_chan_spec_ext_info *ext_info;
s32 numerator;
s32 denominator;
};
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);
unsigned long long tmp;
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
return iio_read_channel_raw(rescale->source, val);
case IIO_CHAN_INFO_SCALE:
ret = iio_read_channel_scale(rescale->source, val, val2);
switch (ret) {
case IIO_VAL_FRACTIONAL:
*val *= rescale->numerator;
*val2 *= rescale->denominator;
return ret;
case IIO_VAL_INT:
*val *= rescale->numerator;
if (rescale->denominator == 1)
return ret;
*val2 = rescale->denominator;
return IIO_VAL_FRACTIONAL;
case IIO_VAL_FRACTIONAL_LOG2:
tmp = *val * 1000000000LL;
do_div(tmp, rescale->denominator);
tmp *= rescale->numerator;
do_div(tmp, 1000000000LL);
*val = tmp;
return ret;
default:
return -EOPNOTSUPP;
}
default:
return -EINVAL;
}
}
static int rescale_read_avail(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
const int **vals, int *type, int *length,
long mask)
{
struct rescale *rescale = iio_priv(indio_dev);
switch (mask) {
case IIO_CHAN_INFO_RAW:
*type = IIO_VAL_INT;
return iio_read_avail_channel_raw(rescale->source,
vals, length);
default:
return -EINVAL;
}
}
static const struct iio_info rescale_info = {
.read_raw = rescale_read_raw,
.read_avail = rescale_read_avail,
};
static ssize_t rescale_read_ext_info(struct iio_dev *indio_dev,
uintptr_t private,
struct iio_chan_spec const *chan,
char *buf)
{
struct rescale *rescale = iio_priv(indio_dev);
return iio_read_channel_ext_info(rescale->source,
rescale->ext_info[private].name,
buf);
}
static ssize_t rescale_write_ext_info(struct iio_dev *indio_dev,
uintptr_t private,
struct iio_chan_spec const *chan,
const char *buf, size_t len)
{
struct rescale *rescale = iio_priv(indio_dev);
return iio_write_channel_ext_info(rescale->source,
rescale->ext_info[private].name,
buf, len);
}
static int rescale_configure_channel(struct device *dev,
struct rescale *rescale)
{
struct iio_chan_spec *chan = &rescale->chan;
struct iio_chan_spec const *schan = rescale->source->channel;
chan->indexed = 1;
chan->output = schan->output;
chan->ext_info = rescale->ext_info;
chan->type = rescale->cfg->type;
if (!iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) ||
!iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE)) {
dev_err(dev, "source channel does not support raw/scale\n");
return -EINVAL;
}
chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE);
if (iio_channel_has_available(schan, IIO_CHAN_INFO_RAW))
chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW);
return 0;
}
static int rescale_current_sense_amplifier_props(struct device *dev,
struct rescale *rescale)
{
u32 sense;
u32 gain_mult = 1;
u32 gain_div = 1;
u32 factor;
int ret;
ret = device_property_read_u32(dev, "sense-resistor-micro-ohms",
&sense);
if (ret) {
dev_err(dev, "failed to read the sense resistance: %d\n", ret);
return ret;
}
device_property_read_u32(dev, "sense-gain-mult", &gain_mult);
device_property_read_u32(dev, "sense-gain-div", &gain_div);
/*
* Calculate the scaling factor, 1 / (gain * sense), or
* gain_div / (gain_mult * sense), while trying to keep the
* numerator/denominator from overflowing.
*/
factor = gcd(sense, 1000000);
rescale->numerator = 1000000 / factor;
rescale->denominator = sense / factor;
factor = gcd(rescale->numerator, gain_mult);
rescale->numerator /= factor;
rescale->denominator *= gain_mult / factor;
factor = gcd(rescale->denominator, gain_div);
rescale->numerator *= gain_div / factor;
rescale->denominator /= factor;
return 0;
}
static int rescale_current_sense_shunt_props(struct device *dev,
struct rescale *rescale)
{
u32 shunt;
u32 factor;
int ret;
ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms",
&shunt);
if (ret) {
dev_err(dev, "failed to read the shunt resistance: %d\n", ret);
return ret;
}
factor = gcd(shunt, 1000000);
rescale->numerator = 1000000 / factor;
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;
}
enum rescale_variant {
CURRENT_SENSE_AMPLIFIER,
CURRENT_SENSE_SHUNT,
VOLTAGE_DIVIDER,
};
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,
},
};
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], },
{ /* 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 = of_device_get_match_data(dev);
rescale->numerator = 1;
rescale->denominator = 1;
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");
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