dma: imx-sdma: move to generic device tree bindings

Update imx-sdma driver to adopt generic DMA device tree bindings. It
calls of_dma_controller_register() with imx-sdma specific of_dma_xlate
to get the generic DMA device tree helper support. The #dma-cells for
imx-sdma must be 3, which includes request ID, peripheral type and
priority.

The existing way of requesting channel, clients directly call
dma_request_channel(), still work there, and will be removed after
all imx-sdma clients get converted to generic DMA device tree helper.

Signed-off-by: Shawn Guo <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>

Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt

···
 - compatible : Should be "fsl,<chip>-sdma"
 - reg : Should contain SDMA registers location and length
 - interrupts : Should contain SDMA interrupt
+- #dma-cells : Must be <3>.
+  The first cell specifies the DMA request/event ID.  See details below
+  about the second and third cell.
 - fsl,sdma-ram-script-name : Should contain the full path of SDMA RAM
   scripts firmware
+
+The second cell of dma phandle specifies the peripheral type of DMA transfer.
+The full ID of peripheral types can be found below.
+
+	ID	transfer type
+	---------------------
+	0	MCU domain SSI
+	1	Shared SSI
+	2	MMC
+	3	SDHC
+	4	MCU domain UART
+	5	Shared UART
+	6	FIRI
+	7	MCU domain CSPI
+	8	Shared CSPI
+	9	SIM
+	10	ATA
+	11	CCM
+	12	External peripheral
+	13	Memory Stick Host Controller
+	14	Shared Memory Stick Host Controller
+	15	DSP
+	16	Memory
+	17	FIFO type Memory
+	18	SPDIF
+	19	IPU Memory
+	20	ASRC
+	21	ESAI
+
+The third cell specifies the transfer priority as below.
+
+	ID	transfer priority
+	-------------------------
+	0	High
+	1	Medium
+	2	Low
 
 Examples:
 
···
 	compatible = "fsl,imx51-sdma", "fsl,imx35-sdma";
 	reg = <0x83fb0000 0x4000>;
 	interrupts = <6>;
+	#dma-cells = <3>;
 	fsl,sdma-ram-script-name = "sdma-imx51.bin";
+};
+
+DMA clients connected to the i.MX SDMA controller must use the format
+described in the dma.txt file.
+
+Examples:
+
+ssi2: ssi@70014000 {
+	compatible = "fsl,imx51-ssi", "fsl,imx21-ssi";
+	reg = <0x70014000 0x4000>;
+	interrupts = <30>;
+	clocks = <&clks 49>;
+	dmas = <&sdma 24 1 0>,
+	       <&sdma 25 1 0>;
+	dma-names = "rx", "tx";
+	fsl,fifo-depth = <15>;
 };

drivers/dma/imx-sdma.c

···
 #include <linux/dmaengine.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/of_dma.h>
 
 #include <asm/irq.h>
 #include <linux/platform_data/dma-imx-sdma.h>
···
 	return ret;
 }
 
+static bool sdma_filter_fn(struct dma_chan *chan, void *fn_param)
+{
+	struct imx_dma_data *data = fn_param;
+
+	if (!imx_dma_is_general_purpose(chan))
+		return false;
+
+	chan->private = data;
+
+	return true;
+}
+
+static struct dma_chan *sdma_xlate(struct of_phandle_args *dma_spec,
+				   struct of_dma *ofdma)
+{
+	struct sdma_engine *sdma = ofdma->of_dma_data;
+	dma_cap_mask_t mask = sdma->dma_device.cap_mask;
+	struct imx_dma_data data;
+
+	if (dma_spec->args_count != 3)
+		return NULL;
+
+	data.dma_request = dma_spec->args[0];
+	data.peripheral_type = dma_spec->args[1];
+	data.priority = dma_spec->args[2];
+
+	return dma_request_channel(mask, sdma_filter_fn, &data);
+}
+
 static int __init sdma_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *of_id =
···
 		goto err_init;
 	}
 
+	if (np) {
+		ret = of_dma_controller_register(np, sdma_xlate, sdma);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to register controller\n");
+			goto err_register;
+		}
+	}
+
 	dev_info(sdma->dev, "initialized\n");
 
 	return 0;
 
+err_register:
+	dma_async_device_unregister(&sdma->dma_device);
 err_init:
 	kfree(sdma->script_addrs);
 err_alloc: