UIO: add generic UIO platform driver

This patch adds a generic UIO platform driver. It eliminates the need for a
dedicated kernel module for simple platform devices. Users only need to
implement their irq handler in platform code and fill a struct uio_info
there. This helps avoiding code duplication as UIO platform drivers often
share a lot of common code.

Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Signed-off-by: Hans J. Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
index 78e139c..2e9079d 100644
--- a/drivers/uio/Kconfig
+++ b/drivers/uio/Kconfig
@@ -26,6 +26,13 @@
 	  To compile this driver as a module, choose M here: the module
 	  will be called uio_cif.
 
+config UIO_PDRV
+	tristate "Userspace I/O platform driver"
+	help
+	  Generic platform driver for Userspace I/O devices.
+
+	  If you don't know what to do here, say N.
+
 config UIO_SMX
 	tristate "SMX cryptengine UIO interface"
 	default n