[pxe] Notify BIOS via INT 1a,564e for each new network device

Use INT 1a,564e to notify the BIOS of each network device that we
detect.  This provides an opportunity for the BIOS to implement
platform policy such as changing the MAC address by issuing a call to
PXENV_UNDI_SET_STATION_ADDRESS.

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

src/arch/i386/interface/pxe/pxe_call.c

 #include <ipxe/uaccess.h>
 #include <ipxe/init.h>
 #include <ipxe/profile.h>
+#include <ipxe/netdevice.h>
 #include <setjmp.h>
 #include <registers.h>
 #include <biosint.h>
 	return 0;
 }
 
+/**
+ * Notify BIOS of existence of network device
+ *
+ * @v netdev		Network device
+ * @ret rc		Return status code
+ */
+static int pxe_notify ( struct net_device *netdev ) {
+
+	/* Do nothing if we already have a network device */
+	if ( pxe_netdev )
+		return 0;
+
+	/* Activate (and deactivate) PXE stack to notify BIOS */
+	pxe_activate ( netdev );
+	pxe_deactivate();
+
+	return 0;
+}
+
+/** PXE BIOS notification driver */
+struct net_driver pxe_driver __net_driver = {
+	.name = "PXE",
+	.probe = pxe_notify,
+};
+
 REQUIRING_SYMBOL ( pxe_api_call );
 REQUIRE_OBJECT ( pxe_preboot );
 REQUIRE_OBJECT ( pxe_undi );