Re: [PATCH 1/5] iio: humidity: hts221: report available values via read_avail()

Hi Jonathan,

Thanks for the feedback. I have checked with what Sachiko is saying is correct.
The custom attribute was in_humidity_oversampling_ratio_available while
the current on is in_humidityrelative_oversampling_ratio_available because in
industrial_core.c only has [IIO_HUMIDITYRELATIVE] = "humidityrelative".

For this humidity case in particular, would it be better to keep the legacy
implementation while adding the new read_avail()?

The other case declaration will remain changed.

> > Replace the custom oversampling_ratio_available sysfs attributes with
> > the standard IIO read_avail() callback. This lets the IIO core create
> > and format *_available attributes and exposes the lists to
> > in-kernel consumers.
>
> Sashiko points out that there is an ABI change in here as oddly
> the driver uses
> in_humidity_oversampling_ratio_available rather than
> in_humidityrelative_oversampling_ratio_available
>
> Which makes this an ABI fix.  Therefore this should have a fixes
> tag and be moved to the start of the set.  Please check that logic
> though as maybe I'm missing something.

Regards,
Adi Nata

On Mon, Aug 10, 2026 at 8:09 AM Jonathan Cameron <[email protected]> wrote:
>
> On Sat,  8 Aug 2026 17:00:22 +0800
> Adi Nata <[email protected]> wrote:
>
> > Replace the custom oversampling_ratio_available sysfs attributes with
> > the standard IIO read_avail() callback. This lets the IIO core create
> > and format *_available attributes and exposes the lists to
> > in-kernel consumers.
>
> Sashiko points out that there is an ABI change in here as oddly
> the driver uses
> in_humidity_oversampling_ratio_available rather than
> in_humidityrelative_oversampling_ratio_available
>
> Which makes this an ABI fix.  Therefore this should have a fixes
> tag and be moved to the start of the set.  Please check that logic
> though as maybe I'm missing something.
>
> J
> >
> > Signed-off-by: Adi Nata <[email protected]>
> > ---
> >  drivers/iio/humidity/hts221_core.c | 106 +++++++++++------------------
> >  1 file changed, 40 insertions(+), 66 deletions(-)
> >
> > diff --git a/drivers/iio/humidity/hts221_core.c b/drivers/iio/humidity/hts221_core.c
> > index bfeb0a60d3af..76a391f421f5 100644
> > --- a/drivers/iio/humidity/hts221_core.c
> > +++ b/drivers/iio/humidity/hts221_core.c
> > @@ -10,7 +10,6 @@
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> >  #include <linux/device.h>
> > -#include <linux/iio/sysfs.h>
> >  #include <linux/delay.h>
> >  #include <linux/pm.h>
> >  #include <linux/regmap.h>
> > @@ -49,7 +48,7 @@ struct hts221_odr {
> >  struct hts221_avg {
> >       u8 addr;
> >       u8 mask;
> > -     u16 avg_avl[HTS221_AVG_DEPTH];
> > +     int avg_avl[HTS221_AVG_DEPTH];
> >  };
> >
> >  static const struct hts221_odr hts221_odr_table[] = {
> > @@ -58,6 +57,8 @@ static const struct hts221_odr hts221_odr_table[] = {
> >       { 13, 0x03 },   /* 12.5Hz */
> >  };
> >
> > +static const int hts221_odr_avail[] = { 1, 7, 13 };
> > +
> >  static const struct hts221_avg hts221_avg_list[] = {
> >       {
> >               .addr = 0x10,
> > @@ -97,7 +98,11 @@ static const struct iio_chan_spec hts221_channels[] = {
> >                                     BIT(IIO_CHAN_INFO_OFFSET) |
> >                                     BIT(IIO_CHAN_INFO_SCALE) |
> >                                     BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
> > +             .info_mask_separate_available =
> > +                             BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
> >               .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> > +             .info_mask_shared_by_all_available =
> > +                             BIT(IIO_CHAN_INFO_SAMP_FREQ),
> >               .scan_index = 0,
> >               .scan_type = {
> >                       .sign = 's',
> > @@ -113,7 +118,11 @@ static const struct iio_chan_spec hts221_channels[] = {
> >                                     BIT(IIO_CHAN_INFO_OFFSET) |
> >                                     BIT(IIO_CHAN_INFO_SCALE) |
> >                                     BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
> > +             .info_mask_separate_available =
> > +                             BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
> >               .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> > +             .info_mask_shared_by_all_available =
> > +                             BIT(IIO_CHAN_INFO_SAMP_FREQ),
> >               .scan_index = 1,
> >               .scan_type = {
> >                       .sign = 's',
> > @@ -192,53 +201,35 @@ static int hts221_update_avg(struct hts221_hw *hw,
> >       return 0;
> >  }
> >
> > -static ssize_t hts221_sysfs_sampling_freq(struct device *dev,
> > -                                       struct device_attribute *attr,
> > -                                       char *buf)
> > -{
> > -     int i;
> > -     ssize_t len = 0;
> > -
> > -     for (i = 0; i < ARRAY_SIZE(hts221_odr_table); i++)
> > -             len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
> > -                              hts221_odr_table[i].hz);
> > -     buf[len - 1] = '\n';
> > -
> > -     return len;
> > -}
> > -
> > -static ssize_t
> > -hts221_sysfs_rh_oversampling_avail(struct device *dev,
> > -                                struct device_attribute *attr,
> > -                                char *buf)
> > -{
> > -     const struct hts221_avg *avg = &hts221_avg_list[HTS221_SENSOR_H];
> > -     ssize_t len = 0;
> > -     int i;
> > -
> > -     for (i = 0; i < ARRAY_SIZE(avg->avg_avl); i++)
> > -             len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
> > -                              avg->avg_avl[i]);
> > -     buf[len - 1] = '\n';
> > -
> > -     return len;
> > -}
> > -
> > -static ssize_t
> > -hts221_sysfs_temp_oversampling_avail(struct device *dev,
> > -                                  struct device_attribute *attr,
> > -                                  char *buf)
> > +static int hts221_read_avail(struct iio_dev *indio_dev,
> > +                          struct iio_chan_spec const *chan,
> > +                          const int **vals, int *type, int *length,
> > +                          long mask)
> >  {
> > -     const struct hts221_avg *avg = &hts221_avg_list[HTS221_SENSOR_T];
> > -     ssize_t len = 0;
> > -     int i;
> > -
> > -     for (i = 0; i < ARRAY_SIZE(avg->avg_avl); i++)
> > -             len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
> > -                              avg->avg_avl[i]);
> > -     buf[len - 1] = '\n';
> > -
> > -     return len;
> > +     switch (mask) {
> > +     case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> > +             switch (chan->type) {
> > +             case IIO_HUMIDITYRELATIVE:
> > +                     *vals = hts221_avg_list[HTS221_SENSOR_H].avg_avl;
> > +                     *length = ARRAY_SIZE(hts221_avg_list[HTS221_SENSOR_H].avg_avl);
> > +                     break;
> > +             case IIO_TEMP:
> > +                     *vals = hts221_avg_list[HTS221_SENSOR_T].avg_avl;
> > +                     *length = ARRAY_SIZE(hts221_avg_list[HTS221_SENSOR_T].avg_avl);
> > +                     break;
> > +             default:
> > +                     return -EINVAL;
> > +             }
> > +             *type = IIO_VAL_INT;
> > +             return IIO_AVAIL_LIST;
> > +     case IIO_CHAN_INFO_SAMP_FREQ:
> > +             *vals = hts221_odr_avail;
> > +             *type = IIO_VAL_INT;
> > +             *length = ARRAY_SIZE(hts221_odr_avail);
> > +             return IIO_AVAIL_LIST;
> > +     default:
> > +             return -EINVAL;
> > +     }
> >  }
> >
> >  int hts221_set_enable(struct hts221_hw *hw, bool enable)
> > @@ -521,27 +512,10 @@ static int hts221_validate_trigger(struct iio_dev *iio_dev,
> >       return hw->trig == trig ? 0 : -EINVAL;
> >  }
> >
> > -static IIO_DEVICE_ATTR(in_humidity_oversampling_ratio_available, S_IRUGO,
> > -                    hts221_sysfs_rh_oversampling_avail, NULL, 0);
> > -static IIO_DEVICE_ATTR(in_temp_oversampling_ratio_available, S_IRUGO,
> > -                    hts221_sysfs_temp_oversampling_avail, NULL, 0);
> > -static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(hts221_sysfs_sampling_freq);
> > -
> > -static struct attribute *hts221_attributes[] = {
> > -     &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
> > -     &iio_dev_attr_in_humidity_oversampling_ratio_available.dev_attr.attr,
> > -     &iio_dev_attr_in_temp_oversampling_ratio_available.dev_attr.attr,
> > -     NULL,
> > -};
> > -
> > -static const struct attribute_group hts221_attribute_group = {
> > -     .attrs = hts221_attributes,
> > -};
> > -
> >  static const struct iio_info hts221_info = {
> > -     .attrs = &hts221_attribute_group,
> >       .read_raw = hts221_read_raw,
> >       .write_raw = hts221_write_raw,
> > +     .read_avail = hts221_read_avail,
> >       .validate_trigger = hts221_validate_trigger,
> >  };
> >
>