1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2022 Schneider Electric
4 *
5 * Clément Léger <clement.leger@bootlin.com>
6 */
7
8#include <linux/bitfield.h>
9#include <linux/etherdevice.h>
10#include <linux/if_ether.h>
11#include <net/dsa.h>
12
13#include "tag.h"
14
15/* To define the outgoing port and to discover the incoming port a TAG is
16 * inserted after Src MAC :
17 *
18 * Dest MAC Src MAC TAG Type
19 * ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 5 6 7 8 | 1 2 |...
20 * |<--------------->|
21 *
22 * See struct a5psw_tag for layout
23 */
24
25#define A5PSW_NAME "a5psw"
26
27#define ETH_P_DSA_A5PSW 0xE001
28#define A5PSW_TAG_LEN 8
29#define A5PSW_CTRL_DATA_FORCE_FORWARD BIT(0)
30/* This is both used for xmit tag and rcv tagging */
31#define A5PSW_CTRL_DATA_PORT GENMASK(3, 0)
32
33struct a5psw_tag {
34 __be16 ctrl_tag;
35 __be16 ctrl_data;
36 __be16 ctrl_data2_hi;
37 __be16 ctrl_data2_lo;
38};
39
40static struct sk_buff *a5psw_tag_xmit(struct sk_buff *skb, struct net_device *dev)
41{
42 struct a5psw_tag *ptag;
43 u32 data2_val;
44
45 BUILD_BUG_ON(sizeof(*ptag) != A5PSW_TAG_LEN);
46
47 /* The Ethernet switch we are interfaced with needs packets to be at
48 * least 60 bytes otherwise they will be discarded when they enter the
49 * switch port logic.
50 */
51 if (__skb_put_padto(skb, ETH_ZLEN, free_on_error: false))
52 return NULL;
53
54 /* provide 'A5PSW_TAG_LEN' bytes additional space */
55 skb_push(skb, A5PSW_TAG_LEN);
56
57 /* make room between MACs and Ether-Type to insert tag */
58 dsa_alloc_etype_header(skb, A5PSW_TAG_LEN);
59
60 ptag = dsa_etype_header_pos_tx(skb);
61
62 data2_val = FIELD_PREP(A5PSW_CTRL_DATA_PORT, dsa_xmit_port_mask(skb, dev));
63 ptag->ctrl_tag = htons(ETH_P_DSA_A5PSW);
64 ptag->ctrl_data = htons(A5PSW_CTRL_DATA_FORCE_FORWARD);
65 ptag->ctrl_data2_lo = htons(data2_val);
66 ptag->ctrl_data2_hi = 0;
67
68 return skb;
69}
70
71static struct sk_buff *a5psw_tag_rcv(struct sk_buff *skb,
72 struct net_device *dev)
73{
74 struct a5psw_tag *tag;
75 int port;
76
77 if (unlikely(!pskb_may_pull(skb, A5PSW_TAG_LEN))) {
78 dev_warn_ratelimited(&dev->dev,
79 "Dropping packet, cannot pull\n");
80 return NULL;
81 }
82
83 tag = dsa_etype_header_pos_rx(skb);
84
85 if (tag->ctrl_tag != htons(ETH_P_DSA_A5PSW)) {
86 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid TAG marker\n");
87 return NULL;
88 }
89
90 port = FIELD_GET(A5PSW_CTRL_DATA_PORT, ntohs(tag->ctrl_data));
91
92 skb->dev = dsa_conduit_find_user(dev, device: 0, port);
93 if (!skb->dev)
94 return NULL;
95
96 skb_pull_rcsum(skb, A5PSW_TAG_LEN);
97 dsa_strip_etype_header(skb, A5PSW_TAG_LEN);
98
99 dsa_default_offload_fwd_mark(skb);
100
101 return skb;
102}
103
104static const struct dsa_device_ops a5psw_netdev_ops = {
105 .name = A5PSW_NAME,
106 .proto = DSA_TAG_PROTO_RZN1_A5PSW,
107 .xmit = a5psw_tag_xmit,
108 .rcv = a5psw_tag_rcv,
109 .needed_headroom = A5PSW_TAG_LEN,
110};
111
112MODULE_DESCRIPTION("DSA tag driver for Renesas RZ/N1 A5PSW switch");
113MODULE_LICENSE("GPL v2");
114MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_A5PSW, A5PSW_NAME);
115module_dsa_tag_driver(a5psw_netdev_ops);
116

source code of linux/net/dsa/tag_rzn1_a5psw.c