Add general registration support for IIO triggers. These
are currently only used to initialize a 'poll' of a given
device. Examples include the lis3l02dq's data ready signal
being used to initialize a read and gpio triggers being
used to allow externally synchronized sensor reading.
Each trigger can cause any number of 'consumer' devices
to be polled with each storing data into a related ring
buffer.
Two stage triggering is supported with 'fast' and 'slow'
paths. The first is used for things like pulling a data
hold line high and the second for actual read which
may take far longer.
Changes since V2:
* As with IIO triggers now use a registration approach
much closer to that of input leading to cleaner code.
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
1637db4441