dma: imx-sdma: use module_platform_driver for SDMA driver

Currently there is no module_exit declared in SDMA driver, so that once
sdma module is inserted, it's shown with permanent attribute by lsmod,
and it can't be removed.
Use module_platform_driver to register/unregister SDMA driver and modify
SDMA's remove operation, to make SDMA driver possible to be removed.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/imx-sdma.c

@@ -1603,6 +1603,8 @@ static int __init sdma_probe(struct platform_device *pdev)
 	sdma->dma_device.dev->dma_parms = &sdma->dma_parms;
 	dma_set_max_seg_size(sdma->dma_device.dev, 65535);
 
+	platform_set_drvdata(pdev, sdma);
+
 	ret = dma_async_device_register(&sdma->dma_device);
 	if (ret) {
 		dev_err(&pdev->dev, "unable to register\n");
@@ -1640,7 +1642,20 @@ err_irq:
 
 static int sdma_remove(struct platform_device *pdev)
 {
-	return -EBUSY;
+	struct sdma_engine *sdma = platform_get_drvdata(pdev);
+	struct resource *iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	int irq = platform_get_irq(pdev, 0);
+
+	dma_async_device_unregister(&sdma->dma_device);
+	kfree(sdma->script_addrs);
+	free_irq(irq, sdma);
+	iounmap(sdma->regs);
+	release_mem_region(iores->start, resource_size(iores));
+	kfree(sdma);
+
+	platform_set_drvdata(pdev, NULL);
+	dev_info(&pdev->dev, "Removed...\n");
+	return 0;
 }
 
 static struct platform_driver sdma_driver = {
@@ -1650,13 +1665,10 @@ static struct platform_driver sdma_driver = {
 	},
 	.id_table	= sdma_devtypes,
 	.remove		= sdma_remove,
+	.probe		= sdma_probe,
 };
 
-static int __init sdma_module_init(void)
-{
-	return platform_driver_probe(&sdma_driver, sdma_probe);
-}
-module_init(sdma_module_init);
+module_platform_driver(sdma_driver);
 
 MODULE_AUTHOR("Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>");
 MODULE_DESCRIPTION("i.MX SDMA driver");