platform/chrome: cros_ec_dev - utilize new cdev_device_add helper function

Replace the open coded registration of the cdev and dev with the
new device_add_cdev() helper. The helper replaces a common pattern by
taking the proper reference against the parent device and adding both
the cdev and the device.

At the same time we cleanup the error path through device_probe
function: we use put_device instead of kfree directly as recommended
by the device_initialize documentation.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/platform/chrome/cros_ec_dev.c

@@ -391,7 +391,6 @@ static int ec_device_probe(struct platform_device *pdev)
 	int retval = -ENOMEM;
 	struct device *dev = &pdev->dev;
 	struct cros_ec_platform *ec_platform = dev_get_platdata(dev);
-	dev_t devno = MKDEV(ec_major, pdev->id);
 	struct cros_ec_dev *ec = kzalloc(sizeof(*ec), GFP_KERNEL);
 
 	if (!ec)
@@ -406,24 +405,12 @@ static int ec_device_probe(struct platform_device *pdev)
 	device_initialize(&ec->class_dev);
 	cdev_init(&ec->cdev, &fops);
 
-	/*
-	 * Add the character device
-	 * Link cdev to the class device to be sure device is not used
-	 * before unbinding it.
-	 */
-	ec->cdev.kobj.parent = &ec->class_dev.kobj;
-	retval = cdev_add(&ec->cdev, devno, 1);
-	if (retval) {
-		dev_err(dev, ": failed to add character device\n");
-		goto cdev_add_failed;
-	}
-
 	/*
 	 * Add the class device
 	 * Link to the character device for creating the /dev entry
 	 * in devtmpfs.
 	 */
-	ec->class_dev.devt = ec->cdev.dev;
+	ec->class_dev.devt = MKDEV(ec_major, pdev->id);
 	ec->class_dev.class = &cros_class;
 	ec->class_dev.parent = dev;
 	ec->class_dev.release = __remove;
@@ -431,13 +418,13 @@ static int ec_device_probe(struct platform_device *pdev)
 	retval = dev_set_name(&ec->class_dev, "%s", ec_platform->ec_name);
 	if (retval) {
 		dev_err(dev, "dev_set_name failed => %d\n", retval);
-		goto set_named_failed;
+		goto failed;
 	}
 
-	retval = device_add(&ec->class_dev);
+	retval = cdev_device_add(&ec->cdev, &ec->class_dev);
 	if (retval) {
-		dev_err(dev, "device_register failed => %d\n", retval);
-		goto dev_reg_failed;
+		dev_err(dev, "cdev_device_add failed => %d\n", retval);
+		goto failed;
 	}
 
 	/* check whether this EC is a sensor hub. */
@@ -446,12 +433,8 @@ static int ec_device_probe(struct platform_device *pdev)
 
 	return 0;
 
-dev_reg_failed:
-set_named_failed:
-	dev_set_drvdata(dev, NULL);
-	cdev_del(&ec->cdev);
-cdev_add_failed:
-	kfree(ec);
+failed:
+	put_device(&ec->class_dev);
 	return retval;
 }