| Message ID | 20180319170246.26830-4-peda@axentia.se (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 19 Mar 2018 18:02:46 +0100 Peter Rosin <peda@axentia.se> wrote: > If an ADC channel measures the midpoint of a voltage divider, the > interesting voltage is often the voltage over the full resistance. > E.g. if the full voltage it too big for the ADC to handle. > Likewise, if an ADC channel measures the voltage across a resistor, > the interesting value is often the current through the resistor. > > This driver solves both problems by allowing to linearly scale a channel > and by allowing changes to the type of the channel. Or both. > > Signed-off-by: Peter Rosin <peda@axentia.se> A few comments inline, but basically the code looks fine, just questions around naming and bindings to answer. Thanks, Jonathan > --- > MAINTAINERS | 1 + > drivers/iio/wrapper/Kconfig | 9 ++ > drivers/iio/wrapper/Makefile | 1 + > drivers/iio/wrapper/iio-unit-converter.c | 268 +++++++++++++++++++++++++++++++ > 4 files changed, 279 insertions(+) > create mode 100644 drivers/iio/wrapper/iio-unit-converter.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 5dd555c7b1b0..b879289f1318 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -6889,6 +6889,7 @@ M: Peter Rosin <peda@axentia.se> > L: linux-iio@vger.kernel.org > S: Maintained > F: Documentation/devicetree/bindings/iio/wrapper/io-channel-unit-converter.txt > +F: drivers/iio/wrapper/iio-unit-converter.c > > IKANOS/ADI EAGLE ADSL USB DRIVER > M: Matthieu Castet <castet.matthieu@free.fr> > diff --git a/drivers/iio/wrapper/Kconfig b/drivers/iio/wrapper/Kconfig > index f27de347c9b3..16554479264a 100644 > --- a/drivers/iio/wrapper/Kconfig > +++ b/drivers/iio/wrapper/Kconfig > @@ -15,4 +15,13 @@ config IIO_MUX > To compile this driver as a module, choose M here: the > module will be called iio-mux. > > +config IIO_UNIT_CONVERTER > + tristate "IIO unit converter" > + depends on OF || COMPILE_TEST > + help > + Say yes here to build support for the IIO unit converter. > + > + To compile this driver as a module, choose M here: the > + module will be called iio-unit-converter. > + > endmenu > diff --git a/drivers/iio/wrapper/Makefile b/drivers/iio/wrapper/Makefile > index 53a7b78734e3..1b9db53bd420 100644 > --- a/drivers/iio/wrapper/Makefile > +++ b/drivers/iio/wrapper/Makefile > @@ -4,3 +4,4 @@ > > # When adding new entries keep the list in alphabetical order > obj-$(CONFIG_IIO_MUX) += iio-mux.o > +obj-$(CONFIG_IIO_UNIT_CONVERTER) += iio-unit-converter.o > diff --git a/drivers/iio/wrapper/iio-unit-converter.c b/drivers/iio/wrapper/iio-unit-converter.c > new file mode 100644 > index 000000000000..53c126f39e4e > --- /dev/null > +++ b/drivers/iio/wrapper/iio-unit-converter.c > @@ -0,0 +1,268 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * IIO unit converter > + * > + * Copyright (C) 2018 Axentia Technologies AB > + * > + * Author: Peter Rosin <peda@axentia.se> > + */ > + > +#include <linux/err.h> > +#include <linux/iio/consumer.h> > +#include <linux/iio/iio.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> > +#include <linux/property.h> > + > +struct unit_converter { > + struct iio_channel *parent; > + struct iio_dev *indio_dev; > + struct iio_chan_spec chan; > + struct iio_chan_spec_ext_info *ext_info; > + s32 numerator; > + s32 denominator; > +}; > + > +static int unit_converter_read_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + int *val, int *val2, long mask) > +{ > + struct unit_converter *uc = iio_priv(indio_dev); > + unsigned long long tmp; > + int ret; > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + return iio_read_channel_raw(uc->parent, val); > + > + case IIO_CHAN_INFO_SCALE: > + ret = iio_read_channel_scale(uc->parent, val, val2); > + switch (ret) { > + case IIO_VAL_FRACTIONAL: > + *val *= uc->numerator; > + *val2 *= uc->denominator; > + return ret; > + case IIO_VAL_INT: > + *val *= uc->numerator; > + if (uc->denominator == 1) > + return ret; > + *val2 = uc->denominator; > + return IIO_VAL_FRACTIONAL; > + case IIO_VAL_FRACTIONAL_LOG2: > + tmp = *val * 1000000000LL; > + do_div(tmp, uc->denominator); > + tmp *= uc->numerator; > + do_div(tmp, 1000000000LL); > + *val = tmp; > + return ret; > + } > + return -EOPNOTSUPP; Slightly clearer and less likely to give warningss from static checkers if you put that return in a default: > + } > + > + return -EINVAL; > +} > + > +static int unit_converter_read_avail(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + const int **vals, int *type, int *length, > + long mask) > +{ > + struct unit_converter *uc = iio_priv(indio_dev); > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + *type = IIO_VAL_INT; > + return iio_read_avail_channel_raw(uc->parent, vals, length); > + } > + > + return -EINVAL; > +} > + > +static int unit_converter_write_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + int val, int val2, long mask) > +{ > + struct unit_converter *uc = iio_priv(indio_dev); > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + return iio_write_channel_raw(uc->parent, val); Talk me through the logic of having this... Supporting a DAC? Bindings don't talk about that possibility... > + } > + > + return -EINVAL; > +} > + > +static const struct iio_info unit_converter_info = { > + .read_raw = unit_converter_read_raw, > + .read_avail = unit_converter_read_avail, > + .write_raw = unit_converter_write_raw, > +}; > + > +static ssize_t unit_converter_read_ext_info(struct iio_dev *indio_dev, > + uintptr_t private, > + struct iio_chan_spec const *chan, > + char *buf) > +{ > + struct unit_converter *uc = iio_priv(indio_dev); > + > + return iio_read_channel_ext_info(uc->parent, > + uc->ext_info[private].name, > + buf); > +} > + > +static ssize_t unit_converter_write_ext_info(struct iio_dev *indio_dev, > + uintptr_t private, > + struct iio_chan_spec const *chan, > + const char *buf, size_t len) > +{ > + struct unit_converter *uc = iio_priv(indio_dev); > + > + return iio_write_channel_ext_info(uc->parent, > + uc->ext_info[private].name, > + buf, len); > +} > + > +static int unit_converter_configure_channel(struct device *dev, > + struct unit_converter *uc, > + enum iio_chan_type type) > +{ > + struct iio_chan_spec *chan = &uc->chan; > + struct iio_chan_spec const *pchan = uc->parent->channel; > + int ret; > + > + chan->indexed = 1; > + chan->output = pchan->output; > + chan->ext_info = uc->ext_info; > + > + if (type == -1) { > + ret = iio_get_channel_type(uc->parent, &type); > + if (ret < 0) { > + dev_err(dev, "failed to get parent channel type\n"); > + return ret; > + } > + } > + chan->type = type; > + > + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_RAW)) > + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_RAW); if the parent doesn't support RAW, is there a lot of point in carrying on? > + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_SCALE)) > + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_SCALE); > + > + if (iio_channel_has_available(pchan, IIO_CHAN_INFO_RAW)) > + chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW); > + > + chan->channel = 0; > + > + return 0; > +} > + > +static int unit_converter_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct iio_dev *indio_dev; > + struct iio_channel *parent; > + struct unit_converter *uc; > + const char *type_name; > + enum iio_chan_type type = -1; /* default to same as parent */ > + int sizeof_ext_info; > + int sizeof_priv; > + int i; > + int ret; > + > + if (!device_property_read_string(dev, "type", &type_name)) { > + if (!strcmp(type_name, "voltage")) > + type = IIO_VOLTAGE; > + else if (!strcmp(type_name, "current")) > + type = IIO_CURRENT; > + else > + return -EINVAL; > + } > + > + parent = devm_iio_channel_get(dev, "parent"); > + if (IS_ERR(parent)) { > + if (PTR_ERR(parent) != -EPROBE_DEFER) > + dev_err(dev, "failed to get parent channel\n"); > + return PTR_ERR(parent); > + } > + > + sizeof_ext_info = iio_get_channel_ext_info_count(parent); > + if (sizeof_ext_info) { > + sizeof_ext_info += 1; /* one extra entry for the sentinel */ > + sizeof_ext_info *= sizeof(*uc->ext_info); > + } > + > + sizeof_priv = sizeof(*uc) + sizeof_ext_info; > + > + indio_dev = devm_iio_device_alloc(dev, sizeof_priv); > + if (!indio_dev) > + return -ENOMEM; > + > + uc = iio_priv(indio_dev); > + > + uc->numerator = 1; > + uc->denominator = 1; > + device_property_read_u32(dev, "numerator", &uc->numerator); > + device_property_read_u32(dev, "denominator", &uc->denominator); > + if (!uc->numerator || !uc->denominator) { > + dev_err(dev, "invalid scaling factor.\n"); > + return -EINVAL; > + } > + > + platform_set_drvdata(pdev, indio_dev); > + > + uc->parent = parent; > + > + indio_dev->name = dev_name(dev); > + indio_dev->dev.parent = dev; > + indio_dev->info = &unit_converter_info; > + indio_dev->modes = INDIO_DIRECT_MODE; > + indio_dev->channels = &uc->chan; > + indio_dev->num_channels = 1; > + if (sizeof_ext_info) { > + uc->ext_info = devm_kmemdup(dev, > + parent->channel->ext_info, > + sizeof_ext_info, GFP_KERNEL); > + if (!uc->ext_info) > + return -ENOMEM; > + > + for (i = 0; uc->ext_info[i].name; ++i) { > + if (parent->channel->ext_info[i].read) > + uc->ext_info[i].read = unit_converter_read_ext_info; > + if (parent->channel->ext_info[i].write) > + uc->ext_info[i].write = unit_converter_write_ext_info; > + uc->ext_info[i].private = i; > + } > + } > + > + ret = unit_converter_configure_channel(dev, uc, type); > + if (ret < 0) > + return ret; > + > + ret = devm_iio_device_register(dev, indio_dev); > + if (ret) { > + dev_err(dev, "failed to register iio device\n"); > + return ret; > + } Drop the return out of the brackets and get rid of return 0 below. > + > + return 0; > +} > + > +static const struct of_device_id unit_converter_match[] = { > + { .compatible = "io-channel-unit-converter" }, > + { /* sentinel */ } > +}; > +MODULE_DEVICE_TABLE(of, unit_converter_match); > + > +static struct platform_driver unit_converter_driver = { > + .probe = unit_converter_probe, > + .driver = { > + .name = "iio-unit-converter", > + .of_match_table = unit_converter_match, > + }, > +}; > +module_platform_driver(unit_converter_driver); > + > +MODULE_DESCRIPTION("IIO unit converter driver"); > +MODULE_AUTHOR("Peter Rosin <peda@axentia.se>"); > +MODULE_LICENSE("GPL v2"); -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2018-03-24 15:03, Jonathan Cameron wrote: > On Mon, 19 Mar 2018 18:02:46 +0100 > Peter Rosin <peda@axentia.se> wrote: > >> If an ADC channel measures the midpoint of a voltage divider, the >> interesting voltage is often the voltage over the full resistance. >> E.g. if the full voltage it too big for the ADC to handle. >> Likewise, if an ADC channel measures the voltage across a resistor, >> the interesting value is often the current through the resistor. >> >> This driver solves both problems by allowing to linearly scale a channel >> and by allowing changes to the type of the channel. Or both. >> >> Signed-off-by: Peter Rosin <peda@axentia.se> > A few comments inline, but basically the code looks fine, just questions > around naming and bindings to answer. > > Thanks, > > Jonathan > *snip* >> +static int unit_converter_write_raw(struct iio_dev *indio_dev, >> + struct iio_chan_spec const *chan, >> + int val, int val2, long mask) >> +{ >> + struct unit_converter *uc = iio_priv(indio_dev); >> + >> + switch (mask) { >> + case IIO_CHAN_INFO_RAW: >> + return iio_write_channel_raw(uc->parent, val); > Talk me through the logic of having this... Supporting a DAC? > Bindings don't talk about that possibility... There's no logic at all, and I don't need it. It's just leftovers, should I remove it? >> + } >> + >> + return -EINVAL; >> +} >> + *snip* >> +static int unit_converter_configure_channel(struct device *dev, >> + struct unit_converter *uc, >> + enum iio_chan_type type) >> +{ >> + struct iio_chan_spec *chan = &uc->chan; >> + struct iio_chan_spec const *pchan = uc->parent->channel; >> + int ret; >> + >> + chan->indexed = 1; >> + chan->output = pchan->output; >> + chan->ext_info = uc->ext_info; >> + >> + if (type == -1) { >> + ret = iio_get_channel_type(uc->parent, &type); >> + if (ret < 0) { >> + dev_err(dev, "failed to get parent channel type\n"); >> + return ret; >> + } >> + } >> + chan->type = type; >> + >> + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_RAW)) >> + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_RAW); > if the parent doesn't support RAW, is there a lot of point in carrying on? Nope, better to error out I suppose. But I'm not familiar with channels without RAW, what alternatives are there anyway? >> + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_SCALE)) >> + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_SCALE); >> + >> + if (iio_channel_has_available(pchan, IIO_CHAN_INFO_RAW)) >> + chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW); >> + >> + chan->channel = 0; >> + >> + return 0; >> +} -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 27 Mar 2018 09:42:40 +0200 Peter Rosin <peda@axentia.se> wrote: > On 2018-03-24 15:03, Jonathan Cameron wrote: > > On Mon, 19 Mar 2018 18:02:46 +0100 > > Peter Rosin <peda@axentia.se> wrote: > > > >> If an ADC channel measures the midpoint of a voltage divider, the > >> interesting voltage is often the voltage over the full resistance. > >> E.g. if the full voltage it too big for the ADC to handle. > >> Likewise, if an ADC channel measures the voltage across a resistor, > >> the interesting value is often the current through the resistor. > >> > >> This driver solves both problems by allowing to linearly scale a channel > >> and by allowing changes to the type of the channel. Or both. > >> > >> Signed-off-by: Peter Rosin <peda@axentia.se> > > A few comments inline, but basically the code looks fine, just questions > > around naming and bindings to answer. > > > > Thanks, > > > > Jonathan > > > > *snip* > > >> +static int unit_converter_write_raw(struct iio_dev *indio_dev, > >> + struct iio_chan_spec const *chan, > >> + int val, int val2, long mask) > >> +{ > >> + struct unit_converter *uc = iio_priv(indio_dev); > >> + > >> + switch (mask) { > >> + case IIO_CHAN_INFO_RAW: > >> + return iio_write_channel_raw(uc->parent, val); > > Talk me through the logic of having this... Supporting a DAC? > > Bindings don't talk about that possibility... > > There's no logic at all, and I don't need it. It's just leftovers, > should I remove it? > > >> + } > >> + > >> + return -EINVAL; > >> +} > >> + > > *snip* > > >> +static int unit_converter_configure_channel(struct device *dev, > >> + struct unit_converter *uc, > >> + enum iio_chan_type type) > >> +{ > >> + struct iio_chan_spec *chan = &uc->chan; > >> + struct iio_chan_spec const *pchan = uc->parent->channel; > >> + int ret; > >> + > >> + chan->indexed = 1; > >> + chan->output = pchan->output; > >> + chan->ext_info = uc->ext_info; > >> + > >> + if (type == -1) { > >> + ret = iio_get_channel_type(uc->parent, &type); > >> + if (ret < 0) { > >> + dev_err(dev, "failed to get parent channel type\n"); > >> + return ret; > >> + } > >> + } > >> + chan->type = type; > >> + > >> + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_RAW)) > >> + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_RAW); > > if the parent doesn't support RAW, is there a lot of point in carrying on? > > Nope, better to error out I suppose. But I'm not familiar with channels > without RAW, what alternatives are there anyway? Potentially _PROCESSED though that will need somewhat different handling. A nasty trick for that might be to map it to RAW and then have the SCALE reflect the divider circuit scale only. It's perfectly possible to have channels with neither _RAW or _PROCESSED but I suspect we don't care about them here. There might be an application that needs to do buffered data flows in the long run, but we can figure out how to do that when one exists. It won't be a huge amount more than you have here, though we might need a trigger pass through as well to allow you to set the trigger for the front end and having it automatically applied to the backend. Jonathan > > >> + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_SCALE)) > >> + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_SCALE); > >> + > >> + if (iio_channel_has_available(pchan, IIO_CHAN_INFO_RAW)) > >> + chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW); > >> + > >> + chan->channel = 0; > >> + > >> + return 0; > >> +} > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2018-03-27 15:22, Jonathan Cameron wrote: > On Tue, 27 Mar 2018 09:42:40 +0200 > Peter Rosin <peda@axentia.se> wrote: >> On 2018-03-24 15:03, Jonathan Cameron wrote: >>> On Mon, 19 Mar 2018 18:02:46 +0100 >>> Peter Rosin <peda@axentia.se> wrote: >>>> + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_RAW)) >>>> + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_RAW); >>> if the parent doesn't support RAW, is there a lot of point in carrying on? >> >> Nope, better to error out I suppose. But I'm not familiar with channels >> without RAW, what alternatives are there anyway? > > Potentially _PROCESSED though that will need somewhat different handling. > A nasty trick for that might be to map it to RAW and then have the SCALE > reflect the divider circuit scale only. Hmm, I think a lot of things might assume RAW to be a pure integer, and maybe they are even correct to do so? So yes, that seems nasty indeed... > It's perfectly possible to have channels with neither _RAW or _PROCESSED > but I suspect we don't care about them here. > > There might be an application that needs to do buffered data flows in the > long run, but we can figure out how to do that when one exists. > > It won't be a huge amount more than you have here, though we might need > a trigger pass through as well to allow you to set the trigger for > the front end and having it automatically applied to the backend. Yes, this is the same for the iio-mux. I don't need it, I in fact need very little bandwidth for these things. Someone with an itch will have to fill in the buffer/trigger handling... Cheers, Peter -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 27 Mar 2018 15:32:13 +0200 Peter Rosin <peda@axentia.se> wrote: > On 2018-03-27 15:22, Jonathan Cameron wrote: > > On Tue, 27 Mar 2018 09:42:40 +0200 > > Peter Rosin <peda@axentia.se> wrote: > >> On 2018-03-24 15:03, Jonathan Cameron wrote: > >>> On Mon, 19 Mar 2018 18:02:46 +0100 > >>> Peter Rosin <peda@axentia.se> wrote: > >>>> + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_RAW)) > >>>> + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_RAW); > >>> if the parent doesn't support RAW, is there a lot of point in carrying on? > >> > >> Nope, better to error out I suppose. But I'm not familiar with channels > >> without RAW, what alternatives are there anyway? > > > > Potentially _PROCESSED though that will need somewhat different handling. > > A nasty trick for that might be to map it to RAW and then have the SCALE > > reflect the divider circuit scale only. > > Hmm, I think a lot of things might assume RAW to be a pure integer, and > maybe they are even correct to do so? So yes, that seems nasty indeed... Seems unlikely to occur often as ADCs are mostly linear, but you never know... We'll figure it out when it happens. > > > It's perfectly possible to have channels with neither _RAW or _PROCESSED > > but I suspect we don't care about them here. > > > > There might be an application that needs to do buffered data flows in the > > long run, but we can figure out how to do that when one exists. > > > > It won't be a huge amount more than you have here, though we might need > > a trigger pass through as well to allow you to set the trigger for > > the front end and having it automatically applied to the backend. > > Yes, this is the same for the iio-mux. I don't need it, I in fact need > very little bandwidth for these things. Someone with an itch will have > to fill in the buffer/trigger handling... Absolutely! > > Cheers, > Peter > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/MAINTAINERS b/MAINTAINERS index 5dd555c7b1b0..b879289f1318 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6889,6 +6889,7 @@ M: Peter Rosin <peda@axentia.se> L: linux-iio@vger.kernel.org S: Maintained F: Documentation/devicetree/bindings/iio/wrapper/io-channel-unit-converter.txt +F: drivers/iio/wrapper/iio-unit-converter.c IKANOS/ADI EAGLE ADSL USB DRIVER M: Matthieu Castet <castet.matthieu@free.fr> diff --git a/drivers/iio/wrapper/Kconfig b/drivers/iio/wrapper/Kconfig index f27de347c9b3..16554479264a 100644 --- a/drivers/iio/wrapper/Kconfig +++ b/drivers/iio/wrapper/Kconfig @@ -15,4 +15,13 @@ config IIO_MUX To compile this driver as a module, choose M here: the module will be called iio-mux. +config IIO_UNIT_CONVERTER + tristate "IIO unit converter" + depends on OF || COMPILE_TEST + help + Say yes here to build support for the IIO unit converter. + + To compile this driver as a module, choose M here: the + module will be called iio-unit-converter. + endmenu diff --git a/drivers/iio/wrapper/Makefile b/drivers/iio/wrapper/Makefile index 53a7b78734e3..1b9db53bd420 100644 --- a/drivers/iio/wrapper/Makefile +++ b/drivers/iio/wrapper/Makefile @@ -4,3 +4,4 @@ # When adding new entries keep the list in alphabetical order obj-$(CONFIG_IIO_MUX) += iio-mux.o +obj-$(CONFIG_IIO_UNIT_CONVERTER) += iio-unit-converter.o diff --git a/drivers/iio/wrapper/iio-unit-converter.c b/drivers/iio/wrapper/iio-unit-converter.c new file mode 100644 index 000000000000..53c126f39e4e --- /dev/null +++ b/drivers/iio/wrapper/iio-unit-converter.c @@ -0,0 +1,268 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * IIO unit converter + * + * Copyright (C) 2018 Axentia Technologies AB + * + * Author: Peter Rosin <peda@axentia.se> + */ + +#include <linux/err.h> +#include <linux/iio/consumer.h> +#include <linux/iio/iio.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/property.h> + +struct unit_converter { + struct iio_channel *parent; + struct iio_dev *indio_dev; + struct iio_chan_spec chan; + struct iio_chan_spec_ext_info *ext_info; + s32 numerator; + s32 denominator; +}; + +static int unit_converter_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct unit_converter *uc = iio_priv(indio_dev); + unsigned long long tmp; + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + return iio_read_channel_raw(uc->parent, val); + + case IIO_CHAN_INFO_SCALE: + ret = iio_read_channel_scale(uc->parent, val, val2); + switch (ret) { + case IIO_VAL_FRACTIONAL: + *val *= uc->numerator; + *val2 *= uc->denominator; + return ret; + case IIO_VAL_INT: + *val *= uc->numerator; + if (uc->denominator == 1) + return ret; + *val2 = uc->denominator; + return IIO_VAL_FRACTIONAL; + case IIO_VAL_FRACTIONAL_LOG2: + tmp = *val * 1000000000LL; + do_div(tmp, uc->denominator); + tmp *= uc->numerator; + do_div(tmp, 1000000000LL); + *val = tmp; + return ret; + } + return -EOPNOTSUPP; + } + + return -EINVAL; +} + +static int unit_converter_read_avail(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + const int **vals, int *type, int *length, + long mask) +{ + struct unit_converter *uc = iio_priv(indio_dev); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + *type = IIO_VAL_INT; + return iio_read_avail_channel_raw(uc->parent, vals, length); + } + + return -EINVAL; +} + +static int unit_converter_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct unit_converter *uc = iio_priv(indio_dev); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + return iio_write_channel_raw(uc->parent, val); + } + + return -EINVAL; +} + +static const struct iio_info unit_converter_info = { + .read_raw = unit_converter_read_raw, + .read_avail = unit_converter_read_avail, + .write_raw = unit_converter_write_raw, +}; + +static ssize_t unit_converter_read_ext_info(struct iio_dev *indio_dev, + uintptr_t private, + struct iio_chan_spec const *chan, + char *buf) +{ + struct unit_converter *uc = iio_priv(indio_dev); + + return iio_read_channel_ext_info(uc->parent, + uc->ext_info[private].name, + buf); +} + +static ssize_t unit_converter_write_ext_info(struct iio_dev *indio_dev, + uintptr_t private, + struct iio_chan_spec const *chan, + const char *buf, size_t len) +{ + struct unit_converter *uc = iio_priv(indio_dev); + + return iio_write_channel_ext_info(uc->parent, + uc->ext_info[private].name, + buf, len); +} + +static int unit_converter_configure_channel(struct device *dev, + struct unit_converter *uc, + enum iio_chan_type type) +{ + struct iio_chan_spec *chan = &uc->chan; + struct iio_chan_spec const *pchan = uc->parent->channel; + int ret; + + chan->indexed = 1; + chan->output = pchan->output; + chan->ext_info = uc->ext_info; + + if (type == -1) { + ret = iio_get_channel_type(uc->parent, &type); + if (ret < 0) { + dev_err(dev, "failed to get parent channel type\n"); + return ret; + } + } + chan->type = type; + + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_RAW)) + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_RAW); + if (iio_channel_has_info(pchan, IIO_CHAN_INFO_SCALE)) + chan->info_mask_separate |= BIT(IIO_CHAN_INFO_SCALE); + + if (iio_channel_has_available(pchan, IIO_CHAN_INFO_RAW)) + chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW); + + chan->channel = 0; + + return 0; +} + +static int unit_converter_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct iio_dev *indio_dev; + struct iio_channel *parent; + struct unit_converter *uc; + const char *type_name; + enum iio_chan_type type = -1; /* default to same as parent */ + int sizeof_ext_info; + int sizeof_priv; + int i; + int ret; + + if (!device_property_read_string(dev, "type", &type_name)) { + if (!strcmp(type_name, "voltage")) + type = IIO_VOLTAGE; + else if (!strcmp(type_name, "current")) + type = IIO_CURRENT; + else + return -EINVAL; + } + + parent = devm_iio_channel_get(dev, "parent"); + if (IS_ERR(parent)) { + if (PTR_ERR(parent) != -EPROBE_DEFER) + dev_err(dev, "failed to get parent channel\n"); + return PTR_ERR(parent); + } + + sizeof_ext_info = iio_get_channel_ext_info_count(parent); + if (sizeof_ext_info) { + sizeof_ext_info += 1; /* one extra entry for the sentinel */ + sizeof_ext_info *= sizeof(*uc->ext_info); + } + + sizeof_priv = sizeof(*uc) + sizeof_ext_info; + + indio_dev = devm_iio_device_alloc(dev, sizeof_priv); + if (!indio_dev) + return -ENOMEM; + + uc = iio_priv(indio_dev); + + uc->numerator = 1; + uc->denominator = 1; + device_property_read_u32(dev, "numerator", &uc->numerator); + device_property_read_u32(dev, "denominator", &uc->denominator); + if (!uc->numerator || !uc->denominator) { + dev_err(dev, "invalid scaling factor.\n"); + return -EINVAL; + } + + platform_set_drvdata(pdev, indio_dev); + + uc->parent = parent; + + indio_dev->name = dev_name(dev); + indio_dev->dev.parent = dev; + indio_dev->info = &unit_converter_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = &uc->chan; + indio_dev->num_channels = 1; + if (sizeof_ext_info) { + uc->ext_info = devm_kmemdup(dev, + parent->channel->ext_info, + sizeof_ext_info, GFP_KERNEL); + if (!uc->ext_info) + return -ENOMEM; + + for (i = 0; uc->ext_info[i].name; ++i) { + if (parent->channel->ext_info[i].read) + uc->ext_info[i].read = unit_converter_read_ext_info; + if (parent->channel->ext_info[i].write) + uc->ext_info[i].write = unit_converter_write_ext_info; + uc->ext_info[i].private = i; + } + } + + ret = unit_converter_configure_channel(dev, uc, type); + if (ret < 0) + return ret; + + ret = devm_iio_device_register(dev, indio_dev); + if (ret) { + dev_err(dev, "failed to register iio device\n"); + return ret; + } + + return 0; +} + +static const struct of_device_id unit_converter_match[] = { + { .compatible = "io-channel-unit-converter" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, unit_converter_match); + +static struct platform_driver unit_converter_driver = { + .probe = unit_converter_probe, + .driver = { + .name = "iio-unit-converter", + .of_match_table = unit_converter_match, + }, +}; +module_platform_driver(unit_converter_driver); + +MODULE_DESCRIPTION("IIO unit converter driver"); +MODULE_AUTHOR("Peter Rosin <peda@axentia.se>"); +MODULE_LICENSE("GPL v2");
If an ADC channel measures the midpoint of a voltage divider, the interesting voltage is often the voltage over the full resistance. E.g. if the full voltage it too big for the ADC to handle. Likewise, if an ADC channel measures the voltage across a resistor, the interesting value is often the current through the resistor. This driver solves both problems by allowing to linearly scale a channel and by allowing changes to the type of the channel. Or both. Signed-off-by: Peter Rosin <peda@axentia.se> --- MAINTAINERS | 1 + drivers/iio/wrapper/Kconfig | 9 ++ drivers/iio/wrapper/Makefile | 1 + drivers/iio/wrapper/iio-unit-converter.c | 268 +++++++++++++++++++++++++++++++ 4 files changed, 279 insertions(+) create mode 100644 drivers/iio/wrapper/iio-unit-converter.c