linux-kernel - Re: [PATCH v4 2/2] thermal: thermal-generic-adc: add temperature sensor channel

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Message-ID: <CAPVz0n0NA+=+4da8izPvTn3XacdJndyxrvyMY-QvHdie206wVg@mail.gmail.com>
Date: Sat, 5 Apr 2025 18:23:25 +0300
From: Svyatoslav Ryhel <clamor95@...il.com>
To: Jonathan Cameron <jic23@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Daniel Lezcano <daniel.lezcano@...aro.org>, Zhang Rui <rui.zhang@...el.com>, 
	Lukasz Luba <lukasz.luba@....com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Laxman Dewangan <ldewangan@...dia.com>, Svyatoslav Ryhel <clamor95@...il.com>
Cc: linux-pm@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH v4 2/2] thermal: thermal-generic-adc: add temperature
 sensor channel

пн, 10 бер. 2025 р. о 09:57 Svyatoslav Ryhel <clamor95@...il.com> пише:
>
> 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.
>
> The temperature data, while technically a product of conversion and thus
> categorized as IIO_CHAN_INFO_PROCESSED, maintains its unscaled state
> (milli-degree). To account for this, IIO_CHAN_INFO_RAW is used along with
> IIO_CHAN_INFO_SCALE to provide different degrees of accuracy.
>
> Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
> ---
>  drivers/thermal/thermal-generic-adc.c | 62 ++++++++++++++++++++++++++-
>  1 file changed, 61 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/thermal-generic-adc.c b/drivers/thermal/thermal-generic-adc.c
> index ee3d0aa31406..7dcc2e1168a4 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 +74,65 @@ 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_channel[] = {
> +       {
> +               .type = IIO_TEMP,
> +               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +                                     BIT(IIO_CHAN_INFO_SCALE),
> +       }
> +};
> +
> +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_RAW:
> +               ret = gadc_thermal_get_temp(gtinfo->tz_dev, val);
> +               if (ret)
> +                       return ret;
> +
> +               return IIO_VAL_INT;
> +
> +       case IIO_CHAN_INFO_SCALE:
> +               /* scale to a degree centigrade */
> +               *val = 1;
> +               *val2 = 1000;
> +               return IIO_VAL_FRACTIONAL;
> +
> +       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(struct gadc_thermal_info));
> +       if (!indio_dev)
> +               return -ENOMEM;
> +
> +       gtinfo = iio_priv(indio_dev);
> +       memcpy(gtinfo, gti, sizeof(struct gadc_thermal_info));
> +
> +       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_channel;
> +       indio_dev->num_channels = ARRAY_SIZE(gadc_thermal_iio_channel);
> +
> +       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 +213,7 @@ 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[] = {
> --
> 2.43.0
>

Added Jonathan Cameron and linux-iio@...r.kernel.org to list.

Jonathan, this is newer version of the thermal-generic-adc you have
reviewed recently with channels adjusted like proposed in v3.