DMA-API: dcdbas: update DMA mask handing

dcdbas was explicitly initializing DMA masks thusly:
	dcdbas_pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
	dcdbas_pdev->dev.dma_mask = &dcdbas_pdev->dev.coherent_dma_mask;
which bypasses the architecture check.  Moreover, it is creating the
dcdbas_pdev device itself, and using the platform_device_register_full()
avoids some of this explicit initialization.

Convert the driver to use platform_device_register_full(), and as it
makes use of coherent DMA, also call dma_set_coherent_mask() to ensure
that the architecture gets to check the mask.
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/firmware/dcdbas.c

@@ -545,12 +545,15 @@ static int dcdbas_probe(struct platform_device *dev)
 	host_control_action = HC_ACTION_NONE;
 	host_control_smi_type = HC_SMITYPE_NONE;
 
+	dcdbas_pdev = dev;
+
 	/*
 	 * BIOS SMI calls require buffer addresses be in 32-bit address space.
 	 * This is done by setting the DMA mask below.
 	 */
-	dcdbas_pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
-	dcdbas_pdev->dev.dma_mask = &dcdbas_pdev->dev.coherent_dma_mask;
+	error = dma_set_coherent_mask(&dcdbas_pdev->dev, DMA_BIT_MASK(32));
+	if (error)
+		return error;
 
 	error = sysfs_create_group(&dev->dev.kobj, &dcdbas_attr_group);
 	if (error)
@@ -581,6 +584,14 @@ static struct platform_driver dcdbas_driver = {
 	.remove		= dcdbas_remove,
 };
 
+static const struct platform_device_info dcdbas_dev_info __initdata = {
+	.name		= DRIVER_NAME,
+	.id		= -1,
+	.dma_mask	= DMA_BIT_MASK(32),
+};
+
+static struct platform_device *dcdbas_pdev_reg;
+
 /**
  * dcdbas_init: initialize driver
  */
@@ -592,20 +603,14 @@ static int __init dcdbas_init(void)
 	if (error)
 		return error;
 
-	dcdbas_pdev = platform_device_alloc(DRIVER_NAME, -1);
-	if (!dcdbas_pdev) {
-		error = -ENOMEM;
+	dcdbas_pdev_reg = platform_device_register_full(&dcdbas_dev_info);
+	if (IS_ERR(dcdbas_pdev_reg)) {
+		error = PTR_ERR(dcdbas_pdev_reg);
 		goto err_unregister_driver;
 	}
 
-	error = platform_device_add(dcdbas_pdev);
-	if (error)
-		goto err_free_device;
-
 	return 0;
 
- err_free_device:
-	platform_device_put(dcdbas_pdev);
  err_unregister_driver:
 	platform_driver_unregister(&dcdbas_driver);
 	return error;
@@ -628,8 +633,9 @@ static void __exit dcdbas_exit(void)
 	 * all sysfs attributes belonging to this module have been
 	 * released.
 	 */
-	smi_data_buf_free();
-	platform_device_unregister(dcdbas_pdev);
+	if (dcdbas_pdev)
+		smi_data_buf_free();
+	platform_device_unregister(dcdbas_pdev_reg);
 	platform_driver_unregister(&dcdbas_driver);
 }