diff options
Diffstat (limited to 'drivers/iio/afe')
| -rw-r--r-- | drivers/iio/afe/Kconfig | 19 | ||||
| -rw-r--r-- | drivers/iio/afe/Makefile | 6 | ||||
| -rw-r--r-- | drivers/iio/afe/iio-rescale.c | 359 |
3 files changed, 384 insertions, 0 deletions
diff --git a/drivers/iio/afe/Kconfig b/drivers/iio/afe/Kconfig new file mode 100644 index 0000000..c91eef0 --- /dev/null +++ b/drivers/iio/afe/Kconfig @@ -0,0 +1,19 @@ +# +# Analog Front End drivers +# +# When adding new entries keep the list in alphabetical order + +menu "Analog Front Ends" + +config IIO_RESCALE + tristate "IIO rescale" + depends on OF || COMPILE_TEST + 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 0000000..5fabb7b --- /dev/null +++ b/drivers/iio/afe/Makefile @@ -0,0 +1,6 @@ +# +# 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 0000000..e9ceee6 --- /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"); |
