dmaengine: usb-dmac: Add Renesas USB DMA Controller (USB-DMAC) driver

This DMAC is Renesas USB high-speed module DMA controller that
supports slave transfer.

This USB-DMAC has similar register sets with R-Car Gen2 DMAC, but
the USB-DMAC has specific registers to control the USB transactions.
If this code is added into the rcar-dmac driver, it will become
unreadable. So, this driver is independent from the rcar-dmac.

And, this USB-DMAC uses virt-dma infrastructure.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/sh/Kconfig

@@ -64,3 +64,12 @@ config RCAR_DMAC
 	help
 	  This driver supports the general purpose DMA controller found in the
 	  Renesas R-Car second generation SoCs.
+
+config RENESAS_USB_DMAC
+	tristate "Renesas USB-DMA Controller"
+	depends on ARCH_SHMOBILE || COMPILE_TEST
+	select RENESAS_DMA
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  This driver supports the USB-DMA controller found in the Renesas
+	  SoCs.

drivers/dma/sh/Makefile

@@ -17,3 +17,4 @@ obj-$(CONFIG_SUDMAC) += sudmac.o
 obj-$(CONFIG_RCAR_HPB_DMAE) += rcar-hpbdma.o
 obj-$(CONFIG_RCAR_AUDMAC_PP) += rcar-audmapp.o
 obj-$(CONFIG_RCAR_DMAC) += rcar-dmac.o
+obj-$(CONFIG_RENESAS_USB_DMAC) += usb-dmac.o