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

[Jonathan Cameron <jic23@kernel.org>]

On Sat,  8 Aug 2026 17:00:22 +0800
Adi Nata <adinata.softwareengineer@gmail.com> 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 <adinata.softwareengineer@gmail.com>
> ---
>  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,
>  };
>