1// SPDX-License-Identifier: (GPL-2.0 OR MIT)
 2/*
 3 * net/dsa/tag_hellcreek.c - Hirschmann Hellcreek switch tag format handling
 4 *
 5 * Copyright (C) 2019,2020 Linutronix GmbH
 6 * Author Kurt Kanzenbach <kurt@linutronix.de>
 7 *
 8 * Based on tag_ksz.c.
 9 */
10
11#include <linux/skbuff.h>
12#include <net/dsa.h>
13
14#include "dsa_priv.h"
15
16#define HELLCREEK_TAG_LEN	1
17
18static struct sk_buff *hellcreek_xmit(struct sk_buff *skb,
19				      struct net_device *dev)
20{
21	struct dsa_port *dp = dsa_slave_to_port(dev);
22	u8 *tag;
23
24	/* Tag encoding */
25	tag  = skb_put(skb, HELLCREEK_TAG_LEN);
26	*tag = BIT(dp->index);
27
28	return skb;
29}
30
31static struct sk_buff *hellcreek_rcv(struct sk_buff *skb,
32				     struct net_device *dev,
33				     struct packet_type *pt)
34{
35	/* Tag decoding */
36	u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN;
37	unsigned int port = tag[0] & 0x03;
38
39	skb->dev = dsa_master_find_slave(dev, 0, port);
40	if (!skb->dev) {
41		netdev_warn(dev, "Failed to get source port: %d\n", port);
42		return NULL;
43	}
44
45	pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN);
46
47	skb->offload_fwd_mark = true;
48
49	return skb;
50}
51
52static const struct dsa_device_ops hellcreek_netdev_ops = {
53	.name	  = "hellcreek",
54	.proto	  = DSA_TAG_PROTO_HELLCREEK,
55	.xmit	  = hellcreek_xmit,
56	.rcv	  = hellcreek_rcv,
57	.needed_tailroom = HELLCREEK_TAG_LEN,
58};
59
60MODULE_LICENSE("Dual MIT/GPL");
61MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK);
62
63module_dsa_tag_driver(hellcreek_netdev_ops);