Channel-less IIO events

[Lars-Peter Clausen <lars@metafoo.de>]

Hi,

Some chips generate events which don't really map to a channel, but are
rather chip global. For example over-temperature events.
Do you think this is something we should add support for or should we rather
use a dummy channel, which doesn't report any actual values, for propagating
the event?

My idea for supporting channel-less events is to add a event_mask to struct
iio_info, which would be used just like a channels event_mask, but there
would be no index for the sysfs attributes and for events we would set the
event number to 0xffff.

Thanks
- Lars