[usb] Add support for xHCI host controllers

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Author: mcb30

src/config/config_usb.c

@@ -18,3 +18,6 @@ FILE_LICENCE ( GPL2_OR_LATER );
 /*
  * Drag in USB controllers
  */
+#ifdef USB_HCD_XHCI
+REQUIRE_OBJECT ( xhci );
+#endif

src/config/defaults/pcbios.h

@@ -36,6 +36,8 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define	SANBOOT_PROTO_IB_SRP	/* Infiniband SCSI RDMA protocol */
 #define	SANBOOT_PROTO_FCP	/* Fibre Channel protocol */
 
+#define	USB_HCD_XHCI		/* xHCI USB host controller */
+
 #define	REBOOT_CMD		/* Reboot command */
 #define	CPUID_CMD		/* x86 CPU feature detection command */