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    SubjectRe: [PATCH v3 2/8] iio: inkern: add helpers to query available values from channels
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    On 23/10/16 23:39, Peter Rosin wrote:
    > Specifically a helper for reading the available maximum raw value of a
    > channel and a helper for forwarding read_avail requests for raw values
    > from one iio driver to an iio channel that is consumed.
    >
    > These rather specific helpers are in turn built with generic helpers
    > making it easy to build more helpers for available values as needed.
    >
    > Signed-off-by: Peter Rosin <peda@axentia.se>
    Looks good to me. Just what I was after.

    Jonathan
    > ---
    > drivers/iio/inkern.c | 97 ++++++++++++++++++++++++++++++++++++++++++++
    > include/linux/iio/consumer.h | 29 +++++++++++++
    > include/linux/iio/iio.h | 17 ++++++++
    > 3 files changed, 143 insertions(+)
    >
    > diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
    > index c4757e6367e7..74808f8a187a 100644
    > --- a/drivers/iio/inkern.c
    > +++ b/drivers/iio/inkern.c
    > @@ -703,6 +703,103 @@ int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
    > }
    > EXPORT_SYMBOL_GPL(iio_read_channel_scale);
    >
    > +static int iio_channel_read_avail(struct iio_channel *chan,
    > + const int **vals, int *type, int *length,
    > + enum iio_chan_info_enum info)
    > +{
    > + if (!iio_channel_has_available(chan->channel, info))
    > + return -EINVAL;
    > +
    > + return chan->indio_dev->info->read_avail(chan->indio_dev, chan->channel,
    > + vals, type, length, info);
    > +}
    > +
    > +int iio_read_avail_channel_raw(struct iio_channel *chan,
    > + const int **vals, int *type, int *length)
    > +{
    > + int ret;
    > +
    > + mutex_lock(&chan->indio_dev->info_exist_lock);
    > + if (!chan->indio_dev->info) {
    > + ret = -ENODEV;
    > + goto err_unlock;
    > + }
    > +
    > + ret = iio_channel_read_avail(chan,
    > + vals, type, length, IIO_CHAN_INFO_RAW);
    > +err_unlock:
    > + mutex_unlock(&chan->indio_dev->info_exist_lock);
    > +
    > + return ret;
    > +}
    > +EXPORT_SYMBOL_GPL(iio_read_avail_channel_raw);
    > +
    > +static int iio_channel_read_max(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);
    > + switch (ret) {
    > + case IIO_AVAIL_RANGE:
    > + switch (*type) {
    > + case IIO_VAL_INT:
    > + *val = vals[2];
    > + break;
    > + default:
    > + *val = vals[4];
    > + *val2 = vals[5];
    > + }
    > + 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 max for other iio values */
    > + return -EINVAL;
    > + }
    > + return 0;
    > +
    > + default:
    > + return ret;
    > + }
    > +}
    > +
    > +int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
    > +{
    > + int ret;
    > + int type;
    > +
    > + mutex_lock(&chan->indio_dev->info_exist_lock);
    > + if (!chan->indio_dev->info) {
    > + ret = -ENODEV;
    > + goto err_unlock;
    > + }
    > +
    > + ret = iio_channel_read_max(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
    > +err_unlock:
    > + mutex_unlock(&chan->indio_dev->info_exist_lock);
    > +
    > + return ret;
    > +}
    > +EXPORT_SYMBOL_GPL(iio_read_max_channel_raw);
    > +
    > int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
    > {
    > int ret = 0;
    > diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
    > index 9edccfba1ffb..baab5e45734f 100644
    > --- a/include/linux/iio/consumer.h
    > +++ b/include/linux/iio/consumer.h
    > @@ -226,6 +226,35 @@ int iio_read_channel_processed(struct iio_channel *chan, int *val);
    > int iio_write_channel_raw(struct iio_channel *chan, int val);
    >
    > /**
    > + * iio_read_max_channel_raw() - read maximum available raw value from a given
    > + * channel
    > + * @chan: The channel being queried.
    > + * @val: Value read back.
    > + *
    > + * Note raw reads from iio channels are in adc counts and hence
    > + * scale will need to be applied if standard units are required.
    > + */
    > +int iio_read_max_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.
    > + * @vals: Available values read back.
    > + * @type: Type of available values in vals.
    > + * @length: Number of entries in vals.
    > + *
    > + * Returns an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST.
    > + *
    > + * For ranges, three vals are always returned; min, step and max.
    > + * For lists, all the possible values are enumerated.
    > + *
    > + * Note raw available values from iio channels are in adc counts and
    > + * hence scale will need to be applied if standard units are required.
    > + */
    > +int iio_read_avail_channel_raw(struct iio_channel *chan,
    > + const int **vals, int *type, int *length);
    > +
    > +/**
    > * iio_get_channel_type() - get the type of a channel
    > * @channel: The channel being queried.
    > * @type: The type of the channel.
    > diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
    > index 45b781084a4b..e565701d13ce 100644
    > --- a/include/linux/iio/iio.h
    > +++ b/include/linux/iio/iio.h
    > @@ -315,6 +315,23 @@ static inline bool iio_channel_has_info(const struct iio_chan_spec *chan,
    > (chan->info_mask_shared_by_all & BIT(type));
    > }
    >
    > +/**
    > + * iio_channel_has_available() - Checks if a channel has an available attribute
    > + * @chan: The channel to be queried
    > + * @type: Type of the available attribute to be checked
    > + *
    > + * Returns true if the channels supports reporting available values for the
    > + * given attribute type, false otherwise.
    > + */
    > +static inline bool iio_channel_has_available(const struct iio_chan_spec *chan,
    > + enum iio_chan_info_enum type)
    > +{
    > + return (chan->info_mask_separate_available & BIT(type)) |
    > + (chan->info_mask_shared_by_type_available & BIT(type)) |
    > + (chan->info_mask_shared_by_dir_available & BIT(type)) |
    > + (chan->info_mask_shared_by_all_available & BIT(type));
    > +}
    > +
    > #define IIO_CHAN_SOFT_TIMESTAMP(_si) { \
    > .type = IIO_TIMESTAMP, \
    > .channel = -1, \
    >

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