Index: uspace/lib/usb/include/usb/usb.h
===================================================================
--- uspace/lib/usb/include/usb/usb.h	(revision 79ae36ddc409577eb0da3750b3a7280e034566a2)
+++ uspace/lib/usb/include/usb/usb.h	(revision a9d85df9ee126de8f372c5cec3a11408064ec8ce)
@@ -69,4 +69,6 @@
 	USB_DIRECTION_BOTH
 } usb_direction_t;
+
+const char *usb_str_direction(usb_direction_t);
 
 /** USB speeds. */