On Tue, 23 May 2023 17:12:19 +0200
Herve Codina <herve.codina@xxxxxxxxxxx> 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().
>
> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
Acked-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> ---
> drivers/iio/inkern.c | 70 ++++++++++++++++++++++++++++++++++++
> include/linux/iio/consumer.h | 12 +++++++
> 2 files changed, 82 insertions(+)
>
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index f738db9a0c04..07b26ff8a334 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -915,6 +915,76 @@ 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)
> +{
> + int unused;
> + const int *vals;
> + int length;
> + int ret;
> +
> + if (!val2)
> + val2 = &unused;
> +
> + 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];
> + *val2 = vals[1];
> + }
> + return 0;
> +
> + case IIO_AVAIL_LIST:
> + if (length <= 0)
> + return -EINVAL;
> + switch (*type) {
> + case IIO_VAL_INT:
> + *val = vals[--length];
> + while (length) {
> + if (vals[--length] < *val)
> + *val = vals[length];
> + }
> + break;
> + default:
> + /* FIXME: 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.
