We have several pieces of software that make use of the
userspace interface to the GPIO subsystem.
One important prerequisite to being able to use the userspace GPIO interface
is to be able to put the corresponding package pins into GPIO mode, by
modifying the chip's mux settings.
With Fedora 19 on the Pandaboard, we were able to achieve this by poking
around in /sys/kernel/debug/omap_mux. However, when running Fedora 20, this
directory is empty. My assumption is that this functionality has been
subsumed by the pinctrl subsystem in recent kernels. Unfortunately, there
doesn't seem to be any documented userspace API.
I'd greatly appreciate it if someone could give me some pointers about how
to deal with this issue!
Recently, sorry don't remember which kernel, most of the gpio stuff
moved over to the gpiolib interface which changed some of the user
space access but it at least appears to be documented in
Documentation/gpio/sysfs.txt and at least on my Panda-es running
3.15rc3 there is /sys/class/gpio/export interface which is I suspect
From the pinctl PoV looking at a presentation  on the topic I'm
sure there is a userspace API yet according to page 18, although
there's been quite some water under the bridge since 3.9 but it might
be that the gpiolib stuff above is all you need.
But if you do need the pinctrl stuff there's a bunch of options in
/sys/kernel/debug/pinctrl/ and the files in there map out how the pins
are currently mapped and there's means to change them there too.
I've not had time to play with any of the above but hopefully it gives
you enough of a start/help.