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 <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Benedikt Spranger <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/Kconfig

@@ -84,4 +84,5 @@ source "drivers/auxdisplay/Kconfig"
 
 source "drivers/kvm/Kconfig"
 
+source "drivers/uio/Kconfig"
 endmenu

drivers/Makefile

@@ -40,6 +40,7 @@ obj-$(CONFIG_ATA)		+= ata/
 obj-$(CONFIG_FUSION)		+= message/
 obj-$(CONFIG_FIREWIRE)		+= firewire/
 obj-$(CONFIG_IEEE1394)		+= ieee1394/
+obj-$(CONFIG_UIO)		+= uio/
 obj-y				+= cdrom/
 obj-y				+= auxdisplay/
 obj-$(CONFIG_MTD)		+= mtd/

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

drivers/uio/Makefile

@@ -0,0 +1 @@
+obj-$(CONFIG_UIO) += uio.o