rpmsg: char: Refactor rpmsg_chrdev_eptdev_create function

Introduce the rpmsg_chrdev_eptdev_alloc and rpmsg_chrdev_eptdev_add
internal function to split the allocation part from the device add.

This patch prepares the introduction of a rpmsg channel device for the
char device. An default endpoint will be created,
referenced in the rpmsg_eptdev structure before adding the devices.
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220124102524.295783-9-arnaud.pouliquen@foss.st.com

drivers/rpmsg/rpmsg_char.c

@@ -330,20 +330,18 @@ static void rpmsg_eptdev_release_device(struct device *dev)
 	kfree(eptdev);
 }
 
-int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent,
-			       struct rpmsg_channel_info chinfo)
+static struct rpmsg_eptdev *rpmsg_chrdev_eptdev_alloc(struct rpmsg_device *rpdev,
+						      struct device *parent)
 {
 	struct rpmsg_eptdev *eptdev;
 	struct device *dev;
-	int ret;
 
 	eptdev = kzalloc(sizeof(*eptdev), GFP_KERNEL);
 	if (!eptdev)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	dev = &eptdev->dev;
 	eptdev->rpdev = rpdev;
-	eptdev->chinfo = chinfo;
 
 	mutex_init(&eptdev->ept_lock);
 	spin_lock_init(&eptdev->queue_lock);
@@ -359,6 +357,16 @@ int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent
 	cdev_init(&eptdev->cdev, &rpmsg_eptdev_fops);
 	eptdev->cdev.owner = THIS_MODULE;
 
+	return eptdev;
+}
+
+static int rpmsg_chrdev_eptdev_add(struct rpmsg_eptdev *eptdev, struct rpmsg_channel_info chinfo)
+{
+	struct device *dev = &eptdev->dev;
+	int ret;
+
+	eptdev->chinfo = chinfo;
+
 	ret = ida_simple_get(&rpmsg_minor_ida, 0, RPMSG_DEV_MAX, GFP_KERNEL);
 	if (ret < 0)
 		goto free_eptdev;
@@ -389,6 +397,21 @@ int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent
 
 	return ret;
 }
+
+int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent,
+			       struct rpmsg_channel_info chinfo)
+{
+	struct rpmsg_eptdev *eptdev;
+	int ret;
+
+	eptdev = rpmsg_chrdev_eptdev_alloc(rpdev, parent);
+	if (IS_ERR(eptdev))
+		return PTR_ERR(eptdev);
+
+	ret = rpmsg_chrdev_eptdev_add(eptdev, chinfo);
+
+	return ret;
+}
 EXPORT_SYMBOL(rpmsg_chrdev_eptdev_create);
 
 static int rpmsg_chrdev_init(void)