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

[Peter Meerwald-Stadler]

> 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@xxxxxxxxxx>
> Looks good to me.  Just what I was after.

some comments below
 
> 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

"Note: raw reads..." would be easier...
here and below

why is there no val2 here?

just reading the documentation ("maximum available raw value") I am not 
sure what the function does: does it return the maximum value possible? or 
the maximum value in some internal buffer? maximum value ever seen?

> > + * 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.

no vals2?

> > + * @type:		Type of available values in vals.

it is not clear what type is

> > + * @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

channel

> > + * 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,							\
> > 
> 

-- 

Peter Meerwald-Stadler
+43-664-2444418 (mobile)