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
hellcreek_xmit(struct sk_buff * skb,struct net_device * dev)18 static 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 /* Calculate checksums (if required) before adding the trailer tag to
25 * avoid including it in calculations. That would lead to wrong
26 * checksums after the switch strips the tag.
27 */
28 if (skb->ip_summed == CHECKSUM_PARTIAL &&
29 skb_checksum_help(skb))
30 return NULL;
31
32 /* Tag encoding */
33 tag = skb_put(skb, HELLCREEK_TAG_LEN);
34 *tag = BIT(dp->index);
35
36 return skb;
37 }
38
hellcreek_rcv(struct sk_buff * skb,struct net_device * dev)39 static struct sk_buff *hellcreek_rcv(struct sk_buff *skb,
40 struct net_device *dev)
41 {
42 /* Tag decoding */
43 u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN;
44 unsigned int port = tag[0] & 0x03;
45
46 skb->dev = dsa_master_find_slave(dev, 0, port);
47 if (!skb->dev) {
48 netdev_warn_once(dev, "Failed to get source port: %d\n", port);
49 return NULL;
50 }
51
52 if (pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN))
53 return NULL;
54
55 dsa_default_offload_fwd_mark(skb);
56
57 return skb;
58 }
59
60 static const struct dsa_device_ops hellcreek_netdev_ops = {
61 .name = "hellcreek",
62 .proto = DSA_TAG_PROTO_HELLCREEK,
63 .xmit = hellcreek_xmit,
64 .rcv = hellcreek_rcv,
65 .needed_tailroom = HELLCREEK_TAG_LEN,
66 };
67
68 MODULE_LICENSE("Dual MIT/GPL");
69 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK);
70
71 module_dsa_tag_driver(hellcreek_netdev_ops);
72
