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-rw-r--r--drivers/iio/afe/Kconfig19
-rw-r--r--drivers/iio/afe/Makefile7
-rw-r--r--drivers/iio/afe/iio-rescale.c611
3 files changed, 637 insertions, 0 deletions
diff --git a/drivers/iio/afe/Kconfig b/drivers/iio/afe/Kconfig
new file mode 100644
index 000000000..9a1d95c1c
--- /dev/null
+++ b/drivers/iio/afe/Kconfig
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Analog Front End drivers
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "Analog Front Ends"
+
+config IIO_RESCALE
+ tristate "IIO rescale"
+ help
+ Say yes here to build support for the IIO rescaling
+ that handles voltage dividers, current sense shunts and
+ current sense amplifiers.
+
+ To compile this driver as a module, choose M here: the
+ module will be called iio-rescale.
+
+endmenu
diff --git a/drivers/iio/afe/Makefile b/drivers/iio/afe/Makefile
new file mode 100644
index 000000000..4c56c8edb
--- /dev/null
+++ b/drivers/iio/afe/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for industrial I/O Analog Front Ends (AFE)
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_IIO_RESCALE) += iio-rescale.o
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
new file mode 100644
index 000000000..56e5913ab
--- /dev/null
+++ b/drivers/iio/afe/iio-rescale.c
@@ -0,0 +1,611 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IIO rescale driver
+ *
+ * Copyright (C) 2018 Axentia Technologies AB
+ * Copyright (C) 2022 Liam Beguin <liambeguin@gmail.com>
+ *
+ * Author: Peter Rosin <peda@axentia.se>
+ */
+
+#include <linux/err.h>
+#include <linux/gcd.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+
+#include <linux/iio/afe/rescale.h>
+#include <linux/iio/consumer.h>
+#include <linux/iio/iio.h>
+
+int rescale_process_scale(struct rescale *rescale, int scale_type,
+ int *val, int *val2)
+{
+ s64 tmp;
+ int _val, _val2;
+ s32 rem, rem2;
+ u32 mult;
+ u32 neg;
+
+ switch (scale_type) {
+ case IIO_VAL_INT:
+ *val *= rescale->numerator;
+ if (rescale->denominator == 1)
+ return scale_type;
+ *val2 = rescale->denominator;
+ return IIO_VAL_FRACTIONAL;
+ case IIO_VAL_FRACTIONAL:
+ /*
+ * When the product of both scales doesn't overflow, avoid
+ * potential accuracy loss (for in kernel consumers) by
+ * keeping a fractional representation.
+ */
+ if (!check_mul_overflow(*val, rescale->numerator, &_val) &&
+ !check_mul_overflow(*val2, rescale->denominator, &_val2)) {
+ *val = _val;
+ *val2 = _val2;
+ return IIO_VAL_FRACTIONAL;
+ }
+ fallthrough;
+ case IIO_VAL_FRACTIONAL_LOG2:
+ tmp = (s64)*val * 1000000000LL;
+ tmp = div_s64(tmp, rescale->denominator);
+ tmp *= rescale->numerator;
+
+ tmp = div_s64_rem(tmp, 1000000000LL, &rem);
+ *val = tmp;
+
+ if (!rem)
+ return scale_type;
+
+ if (scale_type == IIO_VAL_FRACTIONAL)
+ tmp = *val2;
+ else
+ tmp = ULL(1) << *val2;
+
+ rem2 = *val % (int)tmp;
+ *val = *val / (int)tmp;
+
+ *val2 = rem / (int)tmp;
+ if (rem2)
+ *val2 += div_s64((s64)rem2 * 1000000000LL, tmp);
+
+ return IIO_VAL_INT_PLUS_NANO;
+ case IIO_VAL_INT_PLUS_NANO:
+ case IIO_VAL_INT_PLUS_MICRO:
+ mult = scale_type == IIO_VAL_INT_PLUS_NANO ? 1000000000L : 1000000L;
+
+ /*
+ * For IIO_VAL_INT_PLUS_{MICRO,NANO} scale types if either *val
+ * OR *val2 is negative the schan scale is negative, i.e.
+ * *val = 1 and *val2 = -0.5 yields -1.5 not -0.5.
+ */
+ neg = *val < 0 || *val2 < 0;
+
+ tmp = (s64)abs(*val) * abs(rescale->numerator);
+ *val = div_s64_rem(tmp, abs(rescale->denominator), &rem);
+
+ tmp = (s64)rem * mult + (s64)abs(*val2) * abs(rescale->numerator);
+ tmp = div_s64(tmp, abs(rescale->denominator));
+
+ *val += div_s64_rem(tmp, mult, val2);
+
+ /*
+ * If only one of the rescaler elements or the schan scale is
+ * negative, the combined scale is negative.
+ */
+ if (neg ^ ((rescale->numerator < 0) ^ (rescale->denominator < 0))) {
+ if (*val)
+ *val = -*val;
+ else
+ *val2 = -*val2;
+ }
+
+ return scale_type;
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+EXPORT_SYMBOL_NS_GPL(rescale_process_scale, IIO_RESCALE);
+
+int rescale_process_offset(struct rescale *rescale, int scale_type,
+ int scale, int scale2, int schan_off,
+ int *val, int *val2)
+{
+ s64 tmp, tmp2;
+
+ switch (scale_type) {
+ case IIO_VAL_FRACTIONAL:
+ tmp = (s64)rescale->offset * scale2;
+ *val = div_s64(tmp, scale) + schan_off;
+ return IIO_VAL_INT;
+ case IIO_VAL_INT:
+ *val = div_s64(rescale->offset, scale) + schan_off;
+ return IIO_VAL_INT;
+ case IIO_VAL_FRACTIONAL_LOG2:
+ tmp = (s64)rescale->offset * (1 << scale2);
+ *val = div_s64(tmp, scale) + schan_off;
+ return IIO_VAL_INT;
+ case IIO_VAL_INT_PLUS_NANO:
+ tmp = (s64)rescale->offset * 1000000000LL;
+ tmp2 = ((s64)scale * 1000000000LL) + scale2;
+ *val = div64_s64(tmp, tmp2) + schan_off;
+ return IIO_VAL_INT;
+ case IIO_VAL_INT_PLUS_MICRO:
+ tmp = (s64)rescale->offset * 1000000LL;
+ tmp2 = ((s64)scale * 1000000LL) + scale2;
+ *val = div64_s64(tmp, tmp2) + schan_off;
+ return IIO_VAL_INT;
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+EXPORT_SYMBOL_NS_GPL(rescale_process_offset, IIO_RESCALE);
+
+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);
+ int scale, scale2;
+ int schan_off = 0;
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (rescale->chan_processed)
+ /*
+ * When only processed channels are supported, we
+ * read the processed data and scale it by 1/1
+ * augmented with whatever the rescaler has calculated.
+ */
+ return iio_read_channel_processed(rescale->source, val);
+ else
+ return iio_read_channel_raw(rescale->source, val);
+
+ case IIO_CHAN_INFO_SCALE:
+ if (rescale->chan_processed) {
+ /*
+ * Processed channels are scaled 1-to-1
+ */
+ *val = 1;
+ *val2 = 1;
+ ret = IIO_VAL_FRACTIONAL;
+ } else {
+ ret = iio_read_channel_scale(rescale->source, val, val2);
+ }
+ return rescale_process_scale(rescale, ret, val, val2);
+ case IIO_CHAN_INFO_OFFSET:
+ /*
+ * Processed channels are scaled 1-to-1 and source offset is
+ * already taken into account.
+ *
+ * In other cases, real world measurement are expressed as:
+ *
+ * schan_scale * (raw + schan_offset)
+ *
+ * Given that the rescaler parameters are applied recursively:
+ *
+ * rescaler_scale * (schan_scale * (raw + schan_offset) +
+ * rescaler_offset)
+ *
+ * Or,
+ *
+ * (rescaler_scale * schan_scale) * (raw +
+ * (schan_offset + rescaler_offset / schan_scale)
+ *
+ * Thus, reusing the original expression the parameters exposed
+ * to userspace are:
+ *
+ * scale = schan_scale * rescaler_scale
+ * offset = schan_offset + rescaler_offset / schan_scale
+ */
+ if (rescale->chan_processed) {
+ *val = rescale->offset;
+ return IIO_VAL_INT;
+ }
+
+ if (iio_channel_has_info(rescale->source->channel,
+ IIO_CHAN_INFO_OFFSET)) {
+ ret = iio_read_channel_offset(rescale->source,
+ &schan_off, NULL);
+ if (ret != IIO_VAL_INT)
+ return ret < 0 ? ret : -EOPNOTSUPP;
+ }
+
+ if (iio_channel_has_info(rescale->source->channel,
+ IIO_CHAN_INFO_SCALE)) {
+ ret = iio_read_channel_scale(rescale->source, &scale, &scale2);
+ return rescale_process_offset(rescale, ret, scale, scale2,
+ schan_off, val, val2);
+ }
+
+ /*
+ * If we get here we have no scale so scale 1:1 but apply
+ * rescaler and offset, if any.
+ */
+ return rescale_process_offset(rescale, IIO_VAL_FRACTIONAL, 1, 1,
+ schan_off, val, val2);
+ 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) ||
+ iio_channel_has_info(schan, IIO_CHAN_INFO_OFFSET))) {
+ dev_info(dev, "using raw+scale/offset source channel\n");
+ } else if (iio_channel_has_info(schan, IIO_CHAN_INFO_PROCESSED)) {
+ dev_info(dev, "using processed channel\n");
+ rescale->chan_processed = true;
+ } else {
+ dev_err(dev, "source channel is not supported\n");
+ return -EINVAL;
+ }
+
+ chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE);
+
+ if (rescale->offset)
+ chan->info_mask_separate |= BIT(IIO_CHAN_INFO_OFFSET);
+
+ /*
+ * Using .read_avail() is fringe to begin with and makes no sense
+ * whatsoever for processed channels, so we make sure that this cannot
+ * be called on a processed channel.
+ */
+ if (iio_channel_has_available(schan, IIO_CHAN_INFO_RAW) &&
+ !rescale->chan_processed)
+ 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;
+}
+
+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");
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