linux-kernel - Re: [PATCH v3 09/12] iio: inkern: Add a helper to query an available minimum raw value

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Date:   Mon, 12 Jun 2023 17:15:45 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v3 09/12] iio: inkern: Add a helper to query an available
 minimum raw value

On Mon, Jun 12, 2023 at 3:30 PM Herve Codina <herve.codina@...tlin.com> wrote:
>
> A helper, iio_read_max_channel_raw() exists to read the available
> maximum raw value of a channel but nothing similar exists to read the
> available minimum raw value.
>
> This new helper, iio_read_min_channel_raw(), fills the hole and can be
> used for reading the available minimum raw value of a channel.
> It is fully based on the existing iio_read_max_channel_raw().

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> ---
>  drivers/iio/inkern.c         | 63 ++++++++++++++++++++++++++++++++++++
>  include/linux/iio/consumer.h | 12 +++++++
>  2 files changed, 75 insertions(+)
>
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index 4331e74191cf..4f383a5ef59f 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -909,6 +909,69 @@ int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
>  }
>  EXPORT_SYMBOL_GPL(iio_read_max_channel_raw);
>
> +static int iio_channel_read_min(struct iio_channel *chan,
> +                               int *val, int *val2, int *type,
> +                               enum iio_chan_info_enum info)
> +{
> +       const int *vals;
> +       int length;
> +       int ret;
> +
> +       ret = iio_channel_read_avail(chan, &vals, type, &length, info);
> +       if (ret < 0)
> +               return ret;
> +
> +       switch (ret) {
> +       case IIO_AVAIL_RANGE:
> +               switch (*type) {
> +               case IIO_VAL_INT:
> +                       *val = vals[0];
> +                       break;
> +               default:
> +                       *val = vals[0];
> +                       if (val2)
> +                               *val2 = vals[1];
> +               }
> +               return 0;
> +
> +       case IIO_AVAIL_LIST:
> +               if (length <= 0)
> +                       return -EINVAL;
> +               switch (*type) {
> +               case IIO_VAL_INT:
> +                       *val = min_array(vals, length);
> +                       break;
> +               default:
> +                       /* TODO: learn about min for other iio values */
> +                       return -EINVAL;
> +               }
> +               return 0;
> +
> +       default:
> +               return -EINVAL;
> +       }
> +}
> +
> +int iio_read_min_channel_raw(struct iio_channel *chan, int *val)
> +{
> +       struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);
> +       int ret;
> +       int type;
> +
> +       mutex_lock(&iio_dev_opaque->info_exist_lock);
> +       if (!chan->indio_dev->info) {
> +               ret = -ENODEV;
> +               goto err_unlock;
> +       }
> +
> +       ret = iio_channel_read_min(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
> +err_unlock:
> +       mutex_unlock(&iio_dev_opaque->info_exist_lock);
> +
> +       return ret;
> +}
> +EXPORT_SYMBOL_GPL(iio_read_min_channel_raw);
> +
>  int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
>  {
>         struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);
> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> index f536820b9cf2..e9910b41d48e 100644
> --- a/include/linux/iio/consumer.h
> +++ b/include/linux/iio/consumer.h
> @@ -301,6 +301,18 @@ int iio_write_channel_raw(struct iio_channel *chan, int val);
>   */
>  int iio_read_max_channel_raw(struct iio_channel *chan, int *val);
>
> +/**
> + * iio_read_min_channel_raw() - read minimum available raw value from a given
> + *                             channel, i.e. the minimum possible value.
> + * @chan:              The channel being queried.
> + * @val:               Value read back.
> + *
> + * Note, if standard units are required, raw reads from iio channels
> + * need the offset (default 0) and scale (default 1) to be applied
> + * as (raw + offset) * scale.
> + */
> +int iio_read_min_channel_raw(struct iio_channel *chan, int *val);
> +
>  /**
>   * iio_read_avail_channel_raw() - read available raw values from a given channel
>   * @chan:              The channel being queried.
> --
> 2.40.1
>


-- 
With Best Regards,
Andy Shevchenko