Re: [PATCH v3 2/8] iio: inkern: add helpers to query available values from channels

[Jonathan Cameron <jic23@kernel.org>]

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,							\
>