[usb] Add basic support for USB keyboards

When USB network card drivers are used, the BIOS' legacy USB
capability is necessarily disabled since there is no way to share the
host controller between the BIOS and iPXE.  This currently results in
USB keyboards becoming non-functional in USB-enabled builds of iPXE.

Fix by adding basic support for USB keyboards, enabled by default in
iPXE builds which include USB support.

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

src/config/config_usb.c

@@ -43,3 +43,10 @@ REQUIRE_OBJECT ( ehci );
 #ifdef USB_HCD_UHCI
 REQUIRE_OBJECT ( uhci );
 #endif
+
+/*
+ * Drag in USB peripherals
+ */
+#ifdef USB_KEYBOARD
+REQUIRE_OBJECT ( usbkbd );
+#endif

src/config/defaults/pcbios.h

@@ -39,6 +39,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define	USB_HCD_XHCI		/* xHCI USB host controller */
 #define	USB_HCD_EHCI		/* EHCI USB host controller */
 #define	USB_HCD_UHCI		/* UHCI USB host controller */
+#define	USB_KEYBOARD		/* USB keyboards */
 
 #define	REBOOT_CMD		/* Reboot command */
 #define	CPUID_CMD		/* x86 CPU feature detection command */

src/config/usb.h

@@ -19,6 +19,12 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 //#undef	USB_HCD_EHCI		/* EHCI USB host controller */
 //#undef	USB_HCD_UHCI		/* UHCI USB host controller */
 
+/*
+ * USB peripherals
+ *
+ */
+//#undef	USB_KEYBOARD		/* USB keyboards */
+
 #include <config/named.h>
 #include NAMED_CONFIG(usb.h)
 #include <config/local/usb.h>