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    Subject[PATCH v6 10/13] iio: inkern: Add a helper to query an available minimum raw value
    Date
    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@bootlin.com>
    Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
    Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.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 19ddd77adb11..7a1f6713318a 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
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