dmaengine: sun4i: Add support for the DMA engine on sun[457]i SoCs

This patch adds support for the DMA engine present on Allwinner A10,
A13, A10S and A20 SoCs. This engine has two kinds of channels: normal
and dedicated. The main difference is in the mode of operation;
while a single normal channel may be operating at any given time,
dedicated channels may operate simultaneously provided there is no
overlap of source or destination.

Hardware documentation can be found on A10 User Manual (section 12), A13
User Manual (section 14) and A20 User Manual (section 1.12)
Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Documentation/devicetree/bindings/dma/sun4i-dma.txt

+Allwinner A10 DMA Controller
+
+This driver follows the generic DMA bindings defined in dma.txt.
+
+Required properties:
+
+- compatible:	Must be "allwinner,sun4i-a10-dma"
+- reg:		Should contain the registers base address and length
+- interrupts:	Should contain a reference to the interrupt used by this device
+- clocks:	Should contain a reference to the parent AHB clock
+- #dma-cells :	Should be 2, first cell denoting normal or dedicated dma,
+		second cell holding the request line number.
+
+Example:
+	dma: dma-controller@01c02000 {
+		compatible = "allwinner,sun4i-a10-dma";
+		reg = <0x01c02000 0x1000>;
+		interrupts = <27>;
+		clocks = <&ahb_gates 6>;
+		#dma-cells = <2>;
+	};
+
+Clients:
+
+DMA clients connected to the Allwinner A10 DMA controller must use the
+format described in the dma.txt file, using a three-cell specifier for
+each channel: a phandle plus two integer cells.
+The three cells in order are:
+
+1. A phandle pointing to the DMA controller.
+2. Whether it is using normal (0) or dedicated (1) channels
+3. The port ID as specified in the datasheet
+
+Example:
+	spi2: spi@01c17000 {
+		compatible = "allwinner,sun4i-a10-spi";
+		reg = <0x01c17000 0x1000>;
+		interrupts = <0 12 4>;
+		clocks = <&ahb_gates 22>, <&spi2_clk>;
+		clock-names = "ahb", "mod";
+		dmas = <&dma 1 29>, <&dma 1 28>;
+		dma-names = "rx", "tx";
+		status = "disabled";
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};

drivers/dma/Kconfig

@@ -434,6 +434,17 @@ config XILINX_VDMA
 	  channels, Memory Mapped to Stream (MM2S) and Stream to
 	  Memory Mapped (S2MM) for the data transfers.
 
+config DMA_SUN4I
+	tristate "Allwinner A10 DMA SoCs support"
+	depends on MACH_SUN4I || MACH_SUN5I || MACH_SUN7I || COMPILE_TEST
+	default (MACH_SUN4I || MACH_SUN5I || MACH_SUN7I)
+	select DMA_ENGINE
+	select DMA_OF
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the DMA controller present in the sun4i,
+	  sun5i and sun7i Allwinner ARM SoCs.
+
 config DMA_SUN6I
 	tristate "Allwinner A31 SoCs DMA support"
 	depends on MACH_SUN6I || MACH_SUN8I || COMPILE_TEST

drivers/dma/Makefile

@@ -55,5 +55,6 @@ obj-y += xilinx/
 obj-$(CONFIG_INTEL_MIC_X100_DMA) += mic_x100_dma.o
 obj-$(CONFIG_NBPFAXI_DMA) += nbpfaxi.o
 obj-$(CONFIG_DMA_SUN6I) += sun6i-dma.o
+obj-$(CONFIG_DMA_SUN4I) += sun4i-dma.o
 obj-$(CONFIG_IMG_MDC_DMA) += img-mdc-dma.o
 obj-$(CONFIG_XGENE_DMA) += xgene-dma.o