tsnep: Support XDP BPF program setup

Implement setup of BPF programs for XDP RX path with command
XDP_SETUP_PROG of ndo_bpf(). This is the final step for XDP RX path
support.

There is no need to reinit the RX queues as they are always prepared for
XDP.

Additionally remove $(tsnep-y) from $(tsnep-objs) because it is added
automatically.

Test results with A53 1.2GHz:

XDP_DROP (samples/bpf/xdp1)
proto 17:     883878 pkt/s

XDP_TX (samples/bpf/xdp2)
proto 17:     255693 pkt/s

XDP_REDIRECT (samples/bpf/xdpsock)
 sock0@eth2:0 rxdrop xdp-drv
                   pps            pkts           1.00
rx                 855,582        5,404,523
tx                 0              0

XDP_REDIRECT (samples/bpf/xdp_redirect)
eth2->eth1         613,267 rx/s   0 err,drop/s   613,272 xmit/s

Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/net/ethernet/engleder/tsnep_xdp.c b/drivers/net/ethernet/engleder/tsnep_xdp.c
new file mode 100644
index 000000000000..4d14cb1fd772
--- /dev/null
+++ b/drivers/net/ethernet/engleder/tsnep_xdp.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2022 Gerhard Engleder <gerhard@engleder-embedded.com> */
+
+#include <linux/if_vlan.h>
+#include <net/xdp_sock_drv.h>
+
+#include "tsnep.h"
+
+int tsnep_xdp_setup_prog(struct tsnep_adapter *adapter, struct bpf_prog *prog,
+			 struct netlink_ext_ack *extack)
+{
+	struct bpf_prog *old_prog;
+
+	old_prog = xchg(&adapter->xdp_prog, prog);
+	if (old_prog)
+		bpf_prog_put(old_prog);
+
+	return 0;
+}