[netdrvr] sfc: sfc: Add self-test support

Add a set of self-tests accessible thorugh ethtool.
Add hardware loopback and TX disable control code to support them.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/sfc/rx.c b/drivers/net/sfc/rx.c
index 9fd1984..6706223 100644
--- a/drivers/net/sfc/rx.c
+++ b/drivers/net/sfc/rx.c
@@ -19,6 +19,7 @@
 #include "rx.h"
 #include "efx.h"
 #include "falcon.h"
+#include "selftest.h"
 #include "workarounds.h"
 
 /* Number of RX descriptors pushed at once. */
@@ -683,6 +684,15 @@
 	struct sk_buff *skb;
 	int lro = efx->net_dev->features & NETIF_F_LRO;
 
+	/* If we're in loopback test, then pass the packet directly to the
+	 * loopback layer, and free the rx_buf here
+	 */
+	if (unlikely(efx->loopback_selftest)) {
+		efx_loopback_rx_packet(efx, rx_buf->data, rx_buf->len);
+		efx_free_rx_buffer(efx, rx_buf);
+		goto done;
+	}
+
 	if (rx_buf->skb) {
 		prefetch(skb_shinfo(rx_buf->skb));