usb: hub: Add a new API to test if a hub device is root hub

Sometimes we need know if a given hub device is root hub or not.
Add a new API to test this. This removes the xHCI driver's own
version is_root_hub() and change to use the new API.

While we are here, remove the unused/commented out get_usb_device()
in the xHCI driver too.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

common/usb_hub.c

@@ -67,6 +67,16 @@ static inline bool usb_hub_is_superspeed(struct usb_device *hdev)
 	return hdev->descriptor.bDeviceProtocol == 3;
 }
 
+#ifdef CONFIG_DM_USB
+bool usb_hub_is_root_hub(struct udevice *hub)
+{
+	if (device_get_uclass_id(hub->parent) != UCLASS_USB_HUB)
+		return true;
+
+	return false;
+}
+#endif
+
 static int usb_get_hub_descriptor(struct usb_device *dev, void *data, int size)
 {
 	unsigned short dtype = USB_DT_HUB;

drivers/usb/host/xhci.c

@@ -1116,26 +1116,6 @@ int usb_lowlevel_stop(int index)
 #endif /* CONFIG_DM_USB */
 
 #ifdef CONFIG_DM_USB
-/*
-static struct usb_device *get_usb_device(struct udevice *dev)
-{
-	struct usb_device *udev;
-
-	if (device_get_uclass_id(dev) == UCLASS_USB)
-		udev = dev_get_uclass_priv(dev);
-	else
-		udev = dev_get_parent_priv(dev);
-
-	return udev;
-}
-*/
-static bool is_root_hub(struct udevice *dev)
-{
-	if (device_get_uclass_id(dev->parent) != UCLASS_USB_HUB)
-		return true;
-
-	return false;
-}
 
 static int xhci_submit_control_msg(struct udevice *dev, struct usb_device *udev,
 				   unsigned long pipe, void *buffer, int length,
@@ -1150,10 +1130,10 @@ static int xhci_submit_control_msg(struct udevice *dev, struct usb_device *udev,
 	hub = udev->dev;
 	if (device_get_uclass_id(hub) == UCLASS_USB_HUB) {
 		/* Figure out our port number on the root hub */
-		if (is_root_hub(hub)) {
+		if (usb_hub_is_root_hub(hub)) {
 			root_portnr = udev->portnr;
 		} else {
-			while (!is_root_hub(hub->parent))
+			while (!usb_hub_is_root_hub(hub->parent))
 				hub = hub->parent;
 			uhop = dev_get_parent_priv(hub);
 			root_portnr = uhop->portnr;

include/usb.h

@@ -776,6 +776,14 @@ int usb_setup_device(struct usb_device *dev, bool do_read,
 		     struct usb_device *parent);
 
 /**
+ * usb_hub_is_root_hub() - Test whether a hub device is root hub or not
+ *
+ * @hub:	USB hub device to test
+ * @return:	true if the hub device is root hub, false otherwise.
+ */
+bool usb_hub_is_root_hub(struct udevice *hub);
+
+/**
  * usb_hub_scan() - Scan a hub and find its devices
  *
  * @hub:	Hub device to scan