--- /dev/null
+// 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");
projects / openwrt / staging / blogic.git / commitdiff