dmaengine:sirf:take clock and enable it while probing

there is hardcode which enabled the clock of dmaengine before,
this patch takes the clock by standard clock API and enable it
in probe.
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/sirf-dma.c

@@ -16,6 +16,7 @@
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/of_platform.h>
+#include <linux/clk.h>
 #include <linux/sirfsoc_dma.h>
 
 #include "dmaengine.h"
@@ -78,6 +79,7 @@ struct sirfsoc_dma {
 	struct sirfsoc_dma_chan		channels[SIRFSOC_DMA_CHANNELS];
 	void __iomem			*base;
 	int				irq;
+	struct clk			*clk;
 	bool				is_marco;
 };
 
@@ -639,6 +641,12 @@ static int sirfsoc_dma_probe(struct platform_device *op)
 		return -EINVAL;
 	}
 
+	sdma->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(sdma->clk)) {
+		dev_err(dev, "failed to get a clock.\n");
+		return PTR_ERR(sdma->clk);
+	}
+
 	ret = of_address_to_resource(dn, 0, &res);
 	if (ret) {
 		dev_err(dev, "Error parsing memory region!\n");
@@ -698,6 +706,8 @@ static int sirfsoc_dma_probe(struct platform_device *op)
 
 	tasklet_init(&sdma->tasklet, sirfsoc_dma_tasklet, (unsigned long)sdma);
 
+	clk_prepare_enable(sdma->clk);
+
 	/* Register DMA engine */
 	dev_set_drvdata(dev, sdma);
 	ret = dma_async_device_register(dma);
@@ -720,6 +730,7 @@ static int sirfsoc_dma_remove(struct platform_device *op)
 	struct device *dev = &op->dev;
 	struct sirfsoc_dma *sdma = dev_get_drvdata(dev);
 
+	clk_disable_unprepare(sdma->clk);
 	dma_async_device_unregister(&sdma->dma);
 	free_irq(sdma->irq, sdma);
 	irq_dispose_mapping(sdma->irq);