dm: implement a DMA uclass

Implement a DMA uclass so that the devices like ethernet, spi,
mmc etc can offload the data transfers from/to the device and
memory.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jagan Teki <jteki@openedev.com>
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index e69de29..58cb6e9 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -0,0 +1,15 @@
+menu "DMA Support"
+
+config DMA
+	bool "Enable Driver Model for DMA drivers"
+	depends on DM
+	help
+	  Enable driver model for DMA. DMA engines can do
+	  asynchronous data transfers without involving the host
+	  CPU. Currently, this framework can be used to offload
+	  memory copies to and from devices like qspi, ethernet
+	  etc Drivers provide methods to access the DMA devices
+	  buses that is used to transfer data to and from memory.
+	  The uclass interface is defined in include/dma.h.
+
+endmenu # menu "DMA Support"