usb: gadget: configfs: pass UDC name via usb_gadget_driver struct

Now when udc-core supports binding to specific UDC by passing
its name via 'udc_name' member of usb_gadget_driver struct,
switch to this generic approach.
Tested-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
[rebased and fixed checkpatch issues]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/configfs.c

@@ -56,7 +56,6 @@ struct gadget_info {
 	struct list_head string_list;
 	struct list_head available_func;
 
-	const char *udc_name;
 	struct usb_composite_driver composite;
 	struct usb_composite_dev cdev;
 	bool use_os_desc;
@@ -233,21 +232,23 @@ static ssize_t gadget_dev_desc_bcdUSB_store(struct config_item *item,
 
 static ssize_t gadget_dev_desc_UDC_show(struct config_item *item, char *page)
 {
-	return sprintf(page, "%s\n", to_gadget_info(item)->udc_name ?: "");
+	char *udc_name = to_gadget_info(item)->composite.gadget_driver.udc_name;
+
+	return sprintf(page, "%s\n", udc_name ?: "");
 }
 
 static int unregister_gadget(struct gadget_info *gi)
 {
 	int ret;
 
-	if (!gi->udc_name)
+	if (!gi->composite.gadget_driver.udc_name)
 		return -ENODEV;
 
 	ret = usb_gadget_unregister_driver(&gi->composite.gadget_driver);
 	if (ret)
 		return ret;
-	kfree(gi->udc_name);
-	gi->udc_name = NULL;
+	kfree(gi->composite.gadget_driver.udc_name);
+	gi->composite.gadget_driver.udc_name = NULL;
 	return 0;
 }
 
@@ -271,14 +272,16 @@ static ssize_t gadget_dev_desc_UDC_store(struct config_item *item,
 		if (ret)
 			goto err;
 	} else {
-		if (gi->udc_name) {
+		if (gi->composite.gadget_driver.udc_name) {
 			ret = -EBUSY;
 			goto err;
 		}
-		ret = usb_udc_attach_driver(name, &gi->composite.gadget_driver);
-		if (ret)
+		gi->composite.gadget_driver.udc_name = name;
+		ret = usb_gadget_probe_driver(&gi->composite.gadget_driver);
+		if (ret) {
+			gi->composite.gadget_driver.udc_name = NULL;
 			goto err;
-		gi->udc_name = name;
+		}
 	}
 	mutex_unlock(&gi->lock);
 	return len;
@@ -427,9 +430,9 @@ static int config_usb_cfg_unlink(
 	 * remove the function.
 	 */
 	mutex_lock(&gi->lock);
-	if (gi->udc_name)
+	if (gi->composite.gadget_driver.udc_name)
 		unregister_gadget(gi);
-	WARN_ON(gi->udc_name);
+	WARN_ON(gi->composite.gadget_driver.udc_name);
 
 	list_for_each_entry(f, &cfg->func_list, list) {
 		if (f->fi == fi) {
@@ -873,10 +876,10 @@ static int os_desc_unlink(struct config_item *os_desc_ci,
 	struct usb_composite_dev *cdev = &gi->cdev;
 
 	mutex_lock(&gi->lock);
-	if (gi->udc_name)
+	if (gi->composite.gadget_driver.udc_name)
 		unregister_gadget(gi);
 	cdev->os_desc_config = NULL;
-	WARN_ON(gi->udc_name);
+	WARN_ON(gi->composite.gadget_driver.udc_name);
 	mutex_unlock(&gi->lock);
 	return 0;
 }