i2c: i2c-mxs: move to use generic DMA helper

With the generic DMA device tree helper supported by mxs-dma driver,
client devices only need to call dma_request_slave_channel() for
requesting a DMA channel from dmaengine.

Signed-off-by: Shawn Guo <[e-mail]>
Reviewed-by: Arnd Bergmann <[e-mail]>
Acked-by: Wolfram Sang <[e-mail]>

Documentation/devicetree/bindings/i2c/i2c-mxs.txt

···
 Required properties:
 - compatible: Should be "fsl,<chip>-i2c"
 - reg: Should contain registers location and length
-- interrupts: Should contain ERROR and DMA interrupts
+- interrupts: Should contain ERROR interrupt number
 - clock-frequency: Desired I2C bus clock frequency in Hz.
                    Only 100000Hz and 400000Hz modes are supported.
-- fsl,i2c-dma-channel: APBX DMA channel for the I2C
+- dmas: DMA specifier, consisting of a phandle to DMA controller node
+  and I2C DMA channel ID.
+  Refer to dma.txt and fsl-mxs-dma.txt for details.
+- dma-names: Must be "rx-tx".
 
 Examples:
 
···
 	#size-cells = <0>;
 	compatible = "fsl,imx28-i2c";
 	reg = <0x80058000 2000>;
-	interrupts = <111 68>;
+	interrupts = <111>;
 	clock-frequency = <100000>;
-	fsl,i2c-dma-channel = <6>;
+	dmas = <&dma_apbx 6>;
+	dma-names = "rx-tx";
 };

drivers/i2c/busses/i2c-mxs.c

···
 #include <linux/of_i2c.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
-#include <linux/fsl/mxs-dma.h>
 
 #define DRIVER_NAME "mxs-i2c"
 
···
 	uint32_t timing1;
 
 	/* DMA support components */
-	int				dma_channel;
 	struct dma_chan         	*dmach;
-	struct mxs_dma_data		dma_data;
 	uint32_t			pio_data[2];
 	uint32_t			addr_data;
 	struct scatterlist		sg_io[2];
···
 	.functionality = mxs_i2c_func,
 };
 
-static bool mxs_i2c_dma_filter(struct dma_chan *chan, void *param)
-{
-	struct mxs_i2c_dev *i2c = param;
-
-	if (!mxs_dma_is_apbx(chan))
-		return false;
-
-	if (chan->chan_id != i2c->dma_channel)
-		return false;
-
-	chan->private = &i2c->dma_data;
-
-	return true;
-}
-
 static void mxs_i2c_derive_timing(struct mxs_i2c_dev *i2c, int speed)
 {
 	/* The I2C block clock run at 24MHz */
···
 	struct device_node *node = dev->of_node;
 	int ret;
 
-	/*
-	 * TODO: This is a temporary solution and should be changed
-	 * to use generic DMA binding later when the helpers get in.
-	 */
-	ret = of_property_read_u32(node, "fsl,i2c-dma-channel",
-				   &i2c->dma_channel);
-	if (ret) {
-		dev_err(dev, "Failed to get DMA channel!\n");
-		return -ENODEV;
-	}
-
 	ret = of_property_read_u32(node, "clock-frequency", &speed);
 	if (ret) {
 		dev_warn(dev, "No I2C speed selected, using 100kHz\n");
···
 	struct pinctrl *pinctrl;
 	struct resource *res;
 	resource_size_t res_size;
-	int err, irq, dmairq;
-	dma_cap_mask_t mask;
+	int err, irq;
 
 	pinctrl = devm_pinctrl_get_select_default(dev);
 	if (IS_ERR(pinctrl))
···
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	irq = platform_get_irq(pdev, 0);
-	dmairq = platform_get_irq(pdev, 1);
 
-	if (!res || irq < 0 || dmairq < 0)
+	if (!res || irq < 0)
 		return -ENOENT;
 
 	res_size = resource_size(res);
···
 	}
 
 	/* Setup the DMA */
-	dma_cap_zero(mask);
-	dma_cap_set(DMA_SLAVE, mask);
-	i2c->dma_data.chan_irq = dmairq;
-	i2c->dmach = dma_request_channel(mask, mxs_i2c_dma_filter, i2c);
+	i2c->dmach = dma_request_slave_channel(dev, "rx-tx");
 	if (!i2c->dmach) {
 		dev_err(dev, "Failed to request dma\n");
 		return -ENODEV;