Bring in USB hub-related files from https://github.com/kaushalparikh/nuttx. This is the work of Kaushal Parikh. This initial commit is incomplete. This is quite a bit more hub logic that needs to come in before the port is complete.

drivers/usbhost/Kconfig

@@ -30,6 +30,13 @@ config USBHOST_ISOC_DISABLE
 		On some architectures, selecting this setting will reduce driver size
 		by disabling isochronous endpoint support
 
+config USBHOST_HUB
+	bool "USB Hub Support"
+	default n
+	depends on EXPERIMENTAL
+	---help---
+		Select this option to build in support for USB hubs.
+
 config USBHOST_MSC
 	bool "Mass Storage Class Support"
 	default n

drivers/usbhost/Make.defs

@@ -1,7 +1,7 @@
 ############################################################################
 # drivers/usbhost/Make.defs
 #
-#   Copyright (C) 2010-2014 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2010-2015 Gregory Nutt. All rights reserved.
 #   Author: Gregory Nutt <gnutt@nuttx.org>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -42,6 +42,10 @@ ifeq ($(CONFIG_USBHOST),y)
 CSRCS += usbhost_registry.c usbhost_registerclass.c usbhost_findclass.c
 CSRCS += usbhost_enumerate.c usbhost_storage.c usbhost_devaddr.c
 
+ifeq ($(CONFIG_USBHOST_HUB),y)
+CSRCS += usbhost_hub.c
+endif
+
 ifeq ($(CONFIG_USBHOST_HIDKBD),y)
 CSRCS += usbhost_hidkbd.c
 endif