linux-kernel - Re: [PATCH v5 1/1] thermal: thermal-generic-adc: add temperature sensor channel

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Message-ID: <CAPVz0n1_8dBT-HP=hPwTcrCh7bvPBsA8My0VOt8isuXVfXAzUw@mail.gmail.com>
Date: Sun, 24 Aug 2025 12:15:58 +0300
From: Svyatoslav Ryhel <clamor95@...il.com>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Zhang Rui <rui.zhang@...el.com>, 
	Lukasz Luba <lukasz.luba@....com>, Jonathan Cameron <jic23@...nel.org>, linux-pm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/1] thermal: thermal-generic-adc: add temperature
 sensor channel

пн, 5 трав. 2025 р. о 11:56 Daniel Lezcano <daniel.lezcano@...aro.org> пише:
>
> On Wed, Apr 30, 2025 at 08:58:07AM +0300, Svyatoslav Ryhel wrote:
> > To avoid duplicating sensor functionality and conversion tables, this
> > design allows converting an ADC IIO channel's output directly into a
> > temperature IIO channel. This is particularly useful for devices where
> > hwmon isn't suitable or where temperature data must be accessible through
> > IIO.
> >
> > One such device is, for example, the MAX17040 fuel gauge.
> >
> > Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
> > ---
> >  drivers/thermal/thermal-generic-adc.c | 55 ++++++++++++++++++++++++++-
> >  1 file changed, 54 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/thermal/thermal-generic-adc.c b/drivers/thermal/thermal-generic-adc.c
> > index ee3d0aa31406..7c844589b153 100644
> > --- a/drivers/thermal/thermal-generic-adc.c
> > +++ b/drivers/thermal/thermal-generic-adc.c
> > @@ -7,6 +7,7 @@
> >   * Author: Laxman Dewangan <ldewangan@...dia.com>
> >   */
> >  #include <linux/iio/consumer.h>
> > +#include <linux/iio/iio.h>
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> >  #include <linux/platform_device.h>
> > @@ -73,6 +74,58 @@ static const struct thermal_zone_device_ops gadc_thermal_ops = {
> >       .get_temp = gadc_thermal_get_temp,
> >  };
> >
> > +static const struct iio_chan_spec gadc_thermal_iio_channels[] = {
> > +     {
> > +             .type = IIO_TEMP,
> > +             .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> > +     }
> > +};
> > +
> > +static int gadc_thermal_read_raw(struct iio_dev *indio_dev,
> > +                              struct iio_chan_spec const *chan,
> > +                              int *val, int *val2, long mask)
> > +{
> > +     struct gadc_thermal_info *gtinfo = iio_priv(indio_dev);
> > +     int ret;
> > +
> > +     switch (mask) {
> > +     case IIO_CHAN_INFO_PROCESSED:
> > +             ret = gadc_thermal_get_temp(gtinfo->tz_dev, val);
> > +             if (ret)
> > +                     return ret;
> > +
> > +             return IIO_VAL_INT;
> > +
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static const struct iio_info gadc_thermal_iio_info = {
> > +     .read_raw = gadc_thermal_read_raw,
> > +};
> > +
> > +static int gadc_iio_register(struct device *dev, struct gadc_thermal_info *gti)
> > +{
> > +     struct gadc_thermal_info *gtinfo;
> > +     struct iio_dev *indio_dev;
> > +
> > +     indio_dev = devm_iio_device_alloc(dev, sizeof(*gtinfo));
> > +     if (!indio_dev)
> > +             return -ENOMEM;
> > +
> > +     gtinfo = iio_priv(indio_dev);
> > +     memcpy(gtinfo, gti, sizeof(*gtinfo));
>
> Why copy the structure ?
>
> Copying the thermal zone device pointer should be enough, no ?
>

iio_device_alloc created its own copy of struct gadc_thermal_info
hence memcpy is used to fill struct gadc_thermal_info allocated by iio
using struct gadc_thermal_info from gadc, or how do you propose to
handle this? Maybe you could provide a code example for better
understanding.

> > +     indio_dev->name = dev_name(dev);
> > +     indio_dev->info = &gadc_thermal_iio_info;
> > +     indio_dev->modes = INDIO_DIRECT_MODE;
> > +     indio_dev->channels = gadc_thermal_iio_channels;
> > +     indio_dev->num_channels = ARRAY_SIZE(gadc_thermal_iio_channels);
> > +
> > +     return devm_iio_device_register(dev, indio_dev);
> > +}
> > +
> >  static int gadc_thermal_read_linear_lookup_table(struct device *dev,
> >                                                struct gadc_thermal_info *gti)
> >  {
> > @@ -153,7 +206,7 @@ static int gadc_thermal_probe(struct platform_device *pdev)
> >
> >       devm_thermal_add_hwmon_sysfs(dev, gti->tz_dev);
> >
> > -     return 0;
> > +     return gadc_iio_register(&pdev->dev, gti);
> >  }
> >
> >  static const struct of_device_id of_adc_thermal_match[] = {
> > --
> > 2.48.1
> >
>
> --
>
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