Say Y here to add a sysfs interface for GPIOs.

This is mostly useful to work around omissions in a system's
kernel support. Those are common in custom and semicustom
hardware assembled using standard kernels with a minimum of
custom patches. In those cases, userspace code may import
a given GPIO from the kernel, if no kernel driver requested it.

Kernel drivers may also request that a particular GPIO be
exported to userspace; this can be useful when debugging.