UIO: Add the User IO core code

This interface allows the ability to write the majority of a driver in
userspace with only a very small shell of a driver in the kernel itself.
It uses a char device and sysfs to interact with a userspace process to
process interrupts and control memory accesses.

See the docbook documentation for more details on how to use this
interface.

From: Hans J. Koch <hjk@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/uio/Kconfig

@@ -0,0 +1,16 @@
+menu "Userspace I/O"
+	depends on !S390
+
+config UIO
+	tristate "Userspace I/O drivers"
+	default n
+	help
+	  Enable this to allow the userspace driver core code to be
+	  built.  This code allows userspace programs easy access to
+	  kernel interrupts and memory locations, allowing some drivers
+	  to be written in userspace.  Note that a small kernel driver
+	  is also required for interrupt handling to work properly.
+
+	  If you don't know what to do here, say N.
+
+endmenu