usb: gadget: factor out two helper functions from composite_bind()

This patch factors out two helper functions from composite_bind()
that is composite_dev_prepare() and its counterpart
composite_dev_cleanup().

This will be used by the configfs which requries a slightly different
bind/setup code because part of its configurations (i.e. config
descripts, cdev, …) are setup in advance and VID/PID and so one should
not be overwritten. Also the setup of ep0 endpoint can be delayed until
the UDC is assigned.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/composite.c

@@ -1394,11 +1394,8 @@ static void __composite_unbind(struct usb_gadget *gadget, bool unbind_driver)
 	if (cdev->driver->unbind && unbind_driver)
 		cdev->driver->unbind(cdev);
 
-	if (cdev->req) {
-		kfree(cdev->req->buf);
-		usb_ep_free_request(gadget->ep0, cdev->req);
-	}
-	device_remove_file(&gadget->dev, &dev_attr_suspended);
+	composite_dev_cleanup(cdev);
+
 	kfree(cdev->def_manufacturer);
 	kfree(cdev);
 	set_gadget_data(gadget, NULL);
@@ -1447,34 +1444,25 @@ static void update_unchanged_dev_desc(struct usb_device_descriptor *new,
 		new->iProduct = iProduct;
 }
 
-static struct usb_composite_driver *to_cdriver(struct usb_gadget_driver *gdrv)
+int composite_dev_prepare(struct usb_composite_driver *composite,
+		struct usb_composite_dev *cdev)
 {
-	return container_of(gdrv, struct usb_composite_driver, gadget_driver);
-}
-
-static int composite_bind(struct usb_gadget *gadget,
-		struct usb_gadget_driver *gdriver)
-{
-	struct usb_composite_dev	*cdev;
-	struct usb_composite_driver	*composite = to_cdriver(gdriver);
-	int				status = -ENOMEM;
-
-	cdev = kzalloc(sizeof *cdev, GFP_KERNEL);
-	if (!cdev)
-		return status;
-
-	spin_lock_init(&cdev->lock);
-	cdev->gadget = gadget;
-	set_gadget_data(gadget, cdev);
-	INIT_LIST_HEAD(&cdev->configs);
+	struct usb_gadget *gadget = cdev->gadget;
+	int ret = -ENOMEM;
 
 	/* preallocate control response and buffer */
 	cdev->req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);
 	if (!cdev->req)
-		goto fail;
+		return -ENOMEM;
+
 	cdev->req->buf = kmalloc(USB_COMP_EP0_BUFSIZ, GFP_KERNEL);
 	if (!cdev->req->buf)
 		goto fail;
+
+	ret = device_create_file(&gadget->dev, &dev_attr_suspended);
+	if (ret)
+		goto fail_dev;
+
 	cdev->req->complete = composite_setup_complete;
 	gadget->ep0->driver_data = cdev;
 
@@ -1492,7 +1480,44 @@ static int composite_bind(struct usb_gadget *gadget,
 	 * we force endpoints to start unassigned; few controller
 	 * drivers will zero ep->driver_data.
 	 */
-	usb_ep_autoconfig_reset(cdev->gadget);
+	usb_ep_autoconfig_reset(gadget);
+	return 0;
+fail_dev:
+	kfree(cdev->req->buf);
+fail:
+	usb_ep_free_request(gadget->ep0, cdev->req);
+	cdev->req = NULL;
+	return ret;
+}
+
+void composite_dev_cleanup(struct usb_composite_dev *cdev)
+{
+	if (cdev->req) {
+		kfree(cdev->req->buf);
+		usb_ep_free_request(cdev->gadget->ep0, cdev->req);
+	}
+	device_remove_file(&cdev->gadget->dev, &dev_attr_suspended);
+}
+
+static int composite_bind(struct usb_gadget *gadget,
+		struct usb_gadget_driver *gdriver)
+{
+	struct usb_composite_dev	*cdev;
+	struct usb_composite_driver	*composite = to_cdriver(gdriver);
+	int				status = -ENOMEM;
+
+	cdev = kzalloc(sizeof *cdev, GFP_KERNEL);
+	if (!cdev)
+		return status;
+
+	spin_lock_init(&cdev->lock);
+	cdev->gadget = gadget;
+	set_gadget_data(gadget, cdev);
+	INIT_LIST_HEAD(&cdev->configs);
+
+	status = composite_dev_prepare(composite, cdev);
+	if (status)
+		goto fail;
 
 	/* composite gadget needs to assign strings for whole device (like
 	 * serial number), register function drivers, potentially update
@@ -1508,11 +1533,6 @@ static int composite_bind(struct usb_gadget *gadget,
 	if (composite->needs_serial && !cdev->desc.iSerialNumber)
 		WARNING(cdev, "userspace failed to provide iSerialNumber\n");
 
-	/* finish up */
-	status = device_create_file(&gadget->dev, &dev_attr_suspended);
-	if (status)
-		goto fail;
-
 	INFO(cdev, "%s ready\n", composite->name);
 	return 0;
 

include/linux/usb/composite.h

@@ -323,7 +323,15 @@ struct usb_composite_driver {
 extern int usb_composite_probe(struct usb_composite_driver *driver);
 extern void usb_composite_unregister(struct usb_composite_driver *driver);
 extern void usb_composite_setup_continue(struct usb_composite_dev *cdev);
+extern int composite_dev_prepare(struct usb_composite_driver *composite,
+		struct usb_composite_dev *cdev);
+void composite_dev_cleanup(struct usb_composite_dev *cdev);
 
+static inline struct usb_composite_driver *to_cdriver(
+		struct usb_gadget_driver *gdrv)
+{
+	return container_of(gdrv, struct usb_composite_driver, gadget_driver);
+}
 
 /**
  * struct usb_composite_device - represents one composite usb gadget