dmaengine: sirf: enable generic dt binding for dma channels

move to support of_dma_request_slave_channel() and dma_request_slave_channel.
we add a xlate() to let dma clients be able to find right dma_chan by generic
"dmas" properties in dts.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

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

@@ -0,0 +1,43 @@
+* CSR SiRFSoC DMA controller
+
+See dma.txt first
+
+Required properties:
+- compatible: Should be "sirf,prima2-dmac" or "sirf,marco-dmac"
+- reg: Should contain DMA registers location and length.
+- interrupts: Should contain one interrupt shared by all channel
+- #dma-cells: must be <1>. used to represent the number of integer
+    cells in the dmas property of client device.
+- clocks: clock required
+
+Example:
+
+Controller:
+dmac0: dma-controller@b00b0000 {
+	compatible = "sirf,prima2-dmac";
+	reg = <0xb00b0000 0x10000>;
+	interrupts = <12>;
+	clocks = <&clks 24>;
+	#dma-cells = <1>;
+};
+
+
+Client:
+Fill the specific dma request line in dmas. In the below example, spi0 read
+channel request line is 9 of the 2nd dma controller, while write channel uses
+4 of the 2nd dma controller; spi1 read channel request line is 12 of the 1st
+dma controller, while write channel uses 13 of the 1st dma controller:
+
+spi0: spi@b00d0000 {
+	compatible = "sirf,prima2-spi";
+	dmas = <&dmac1 9>,
+		<&dmac1 4>;
+	dma-names = "rx", "tx";
+};
+
+spi1: spi@b0170000 {
+	compatible = "sirf,prima2-spi";
+	dmas = <&dmac0 12>,
+		<&dmac0 13>;
+	dma-names = "rx", "tx";
+};

arch/arm/boot/dts/atlas6.dtsi

@@ -269,6 +269,7 @@
 				reg = <0xb00b0000 0x10000>;
 				interrupts = <12>;
 				clocks = <&clks 24>;
+				#dma-cells = <1>;
 			};
 
 			dmac1: dma-controller@b0160000 {
@@ -277,6 +278,7 @@
 				reg = <0xb0160000 0x10000>;
 				interrupts = <13>;
 				clocks = <&clks 25>;
+				#dma-cells = <1>;
 			};
 
 			vip@b00C0000 {

arch/arm/boot/dts/prima2.dtsi

@@ -286,6 +286,7 @@
 				reg = <0xb00b0000 0x10000>;
 				interrupts = <12>;
 				clocks = <&clks 24>;
+				#dma-cells = <1>;
 			};
 
 			dmac1: dma-controller@b0160000 {
@@ -294,6 +295,7 @@
 				reg = <0xb0160000 0x10000>;
 				interrupts = <13>;
 				clocks = <&clks 25>;
+				#dma-cells = <1>;
 			};
 
 			vip@b00C0000 {

drivers/dma/sirf-dma.c

@@ -18,6 +18,7 @@
 #include <linux/of_device.h>
 #include <linux/of_platform.h>
 #include <linux/clk.h>
+#include <linux/of_dma.h>
 #include <linux/sirfsoc_dma.h>
 
 #include "dmaengine.h"
@@ -659,6 +660,18 @@ static int sirfsoc_dma_device_slave_caps(struct dma_chan *dchan,
 	return 0;
 }
 
+static struct dma_chan *of_dma_sirfsoc_xlate(struct of_phandle_args *dma_spec,
+	struct of_dma *ofdma)
+{
+	struct sirfsoc_dma *sdma = ofdma->of_dma_data;
+	unsigned int request = dma_spec->args[0];
+
+	if (request > SIRFSOC_DMA_CHANNELS)
+		return NULL;
+
+	return dma_get_slave_channel(&sdma->channels[request].chan);
+}
+
 static int sirfsoc_dma_probe(struct platform_device *op)
 {
 	struct device_node *dn = op->dev.of_node;
@@ -764,11 +777,20 @@ static int sirfsoc_dma_probe(struct platform_device *op)
 	if (ret)
 		goto free_irq;
 
+	/* Device-tree DMA controller registration */
+	ret = of_dma_controller_register(dn, of_dma_sirfsoc_xlate, sdma);
+	if (ret) {
+		dev_err(dev, "failed to register DMA controller\n");
+		goto unreg_dma_dev;
+	}
+
 	pm_runtime_enable(&op->dev);
 	dev_info(dev, "initialized SIRFSOC DMAC driver\n");
 
 	return 0;
 
+unreg_dma_dev:
+	dma_async_device_unregister(dma);
 free_irq:
 	free_irq(sdma->irq, sdma);
 irq_dispose:
@@ -781,6 +803,7 @@ static int sirfsoc_dma_remove(struct platform_device *op)
 	struct device *dev = &op->dev;
 	struct sirfsoc_dma *sdma = dev_get_drvdata(dev);
 
+	of_dma_controller_free(op->dev.of_node);
 	dma_async_device_unregister(&sdma->dma);
 	free_irq(sdma->irq, sdma);
 	irq_dispose_mapping(sdma->irq);