1 files changed, 359 insertions, 0 deletions

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
new file mode 100644
index 000000000000..e9ceee66d1e7
--- /dev/null
+++ b/drivers/iio/afe/iio-rescale.c
@@ -0,0 +1,359 @@
+// 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)) {
+		if (PTR_ERR(source) != -EPROBE_DEFER)
+			dev_err(dev, "failed to get source channel\n");
+		return PTR_ERR(source);
+	}
+
+	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->dev.parent = 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");