dmaengine: rcar-dmac: Add Renesas R-Car Gen2 DMA Controller (DMAC) driver

The DMAC is a general purpose multi-channel DMA controller that supports
both slave and memcpy transfers.

The driver currently supports the DMAC found in the r8a7790 and r8a7791
SoCs. Support for compatible DMA controllers (such as the audio DMAC)
will be added later.

Feature-wise, automatic hardware handling of descriptors chains isn't
supported yet. LPAE support is implemented.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

drivers/dma/Makefile

@@ -19,7 +19,7 @@ obj-$(CONFIG_AT_HDMAC) += at_hdmac.o
 obj-$(CONFIG_AT_XDMAC) += at_xdmac.o
 obj-$(CONFIG_MX3_IPU) += ipu/
 obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
-obj-$(CONFIG_SH_DMAE_BASE) += sh/
+obj-$(CONFIG_RENESAS_DMA) += sh/
 obj-$(CONFIG_COH901318) += coh901318.o coh901318_lli.o
 obj-$(CONFIG_AMCC_PPC440SPE_ADMA) += ppc4xx/
 obj-$(CONFIG_IMX_SDMA) += imx-sdma.o

drivers/dma/sh/Kconfig

@@ -2,6 +2,10 @@
 # DMA engine configuration for sh
 #
 
+config RENESAS_DMA
+	bool
+	select DMA_ENGINE
+
 #
 # DMA Engine Helpers
 #
@@ -12,7 +16,7 @@ config SH_DMAE_BASE
 	depends on !SUPERH || SH_DMA
 	depends on !SH_DMA_API
 	default y
-	select DMA_ENGINE
+	select RENESAS_DMA
 	help
 	  Enable support for the Renesas SuperH DMA controllers.
 
@@ -52,3 +56,11 @@ config RCAR_AUDMAC_PP
 	depends on SH_DMAE_BASE
 	help
 	  Enable support for the Renesas R-Car Audio DMAC Peripheral Peripheral controllers.
+
+config RCAR_DMAC
+	tristate "Renesas R-Car Gen2 DMA Controller"
+	depends on ARCH_SHMOBILE || COMPILE_TEST
+	select RENESAS_DMA
+	help
+	  This driver supports the general purpose DMA controller found in the
+	  Renesas R-Car second generation SoCs.

drivers/dma/sh/Makefile

@@ -16,3 +16,4 @@ obj-$(CONFIG_SH_DMAE) += shdma.o
 obj-$(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