V4L/DVB: add memory-to-memory device helper framework for videobuf

A mem-to-mem device is a device that uses memory buffers passed by
userspace applications for both their source and destination data. This
is different from existing drivers, which utilize memory buffers for either
input or output, but not both.

In terms of V4L2 such a device would be both of OUTPUT and CAPTURE type.

Examples of such devices would be: image 'resizers', 'rotators',
'colorspace converters', etc.

This patch adds a separate Kconfig sub-menu for mem-to-mem devices as well.

Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Vaibhav Hiremath <hvaibhav@ti.com>
Tested-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/Kconfig

@@ -45,6 +45,10 @@ config VIDEO_TUNER
 	tristate
 	depends on MEDIA_TUNER
 
+config V4L2_MEM2MEM_DEV
+	tristate
+	depends on VIDEOBUF_GEN
+
 #
 # Multimedia Video device configuration
 #
@@ -1121,3 +1125,13 @@ config USB_S2255
 
 endif # V4L_USB_DRIVERS
 endif # VIDEO_CAPTURE_DRIVERS
+
+menuconfig V4L_MEM2MEM_DRIVERS
+	bool "Memory-to-memory multimedia devices"
+	depends on VIDEO_V4L2
+	default n
+	---help---
+	  Say Y here to enable selecting drivers for V4L devices that
+	  use system memory for both source and destination buffers, as opposed
+	  to capture and output drivers, which use memory buffers for just
+	  one of those.

drivers/media/video/Makefile

@@ -117,6 +117,8 @@ obj-$(CONFIG_VIDEOBUF_VMALLOC) += videobuf-vmalloc.o
 obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
 obj-$(CONFIG_VIDEO_BTCX)  += btcx-risc.o
 
+obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
+
 obj-$(CONFIG_VIDEO_M32R_AR_M64278) += arv.o
 
 obj-$(CONFIG_VIDEO_CX2341X) += cx2341x.o