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
33 struct a5psw_tag {
34 __be16 ctrl_tag;
35 __be16 ctrl_data;
36 __be16 ctrl_data2_hi;
37 __be16 ctrl_data2_lo;
38 };
39
40 static struct sk_buff *a5psw_tag_xmit(struct sk_buff *skb, struct net_device *dev)
41 {
42 struct dsa_port *dp = dsa_user_to_port(dev);
43 struct a5psw_tag *ptag;
44 u32 data2_val;
45
46 BUILD_BUG_ON(sizeof(*ptag) != A5PSW_TAG_LEN);
47
48 /* The Ethernet switch we are interfaced with needs packets to be at
49 * least 60 bytes otherwise they will be discarded when they enter the
50 * switch port logic.
51 */
52 if (__skb_put_padto(skb, ETH_ZLEN, false))
53 return NULL;
54
55 /* provide 'A5PSW_TAG_LEN' bytes additional space */
56 skb_push(skb, A5PSW_TAG_LEN);
57
58 /* make room between MACs and Ether-Type to insert tag */
59 dsa_alloc_etype_header(skb, A5PSW_TAG_LEN);
60
61 ptag = dsa_etype_header_pos_tx(skb);
62
63 data2_val = FIELD_PREP(A5PSW_CTRL_DATA_PORT, BIT(dp->index));
64 ptag->ctrl_tag = htons(ETH_P_DSA_A5PSW);
65 ptag->ctrl_data = htons(A5PSW_CTRL_DATA_FORCE_FORWARD);
66 ptag->ctrl_data2_lo = htons(data2_val);
67 ptag->ctrl_data2_hi = 0;
68
69 return skb;
70 }
71
72 static struct sk_buff *a5psw_tag_rcv(struct sk_buff *skb,
73 struct net_device *dev)
74 {
75 struct a5psw_tag *tag;
76 int port;
77
78 if (unlikely(!pskb_may_pull(skb, A5PSW_TAG_LEN))) {
79 dev_warn_ratelimited(&dev->dev,
80 "Dropping packet, cannot pull\n");
81 return NULL;
82 }
83
84 tag = dsa_etype_header_pos_rx(skb);
85
86 if (tag->ctrl_tag != htons(ETH_P_DSA_A5PSW)) {
87 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid TAG marker\n");
88 return NULL;
89 }
90
91 port = FIELD_GET(A5PSW_CTRL_DATA_PORT, ntohs(tag->ctrl_data));
92
93 skb->dev = dsa_conduit_find_user(dev, 0, port);
94 if (!skb->dev)
95 return NULL;
96
97 skb_pull_rcsum(skb, A5PSW_TAG_LEN);
98 dsa_strip_etype_header(skb, A5PSW_TAG_LEN);
99
100 dsa_default_offload_fwd_mark(skb);
101
102 return skb;
103 }
104
105 static const struct dsa_device_ops a5psw_netdev_ops = {
106 .name = A5PSW_NAME,
107 .proto = DSA_TAG_PROTO_RZN1_A5PSW,
108 .xmit = a5psw_tag_xmit,
109 .rcv = a5psw_tag_rcv,
110 .needed_headroom = A5PSW_TAG_LEN,
111 };
112
113 MODULE_DESCRIPTION("DSA tag driver for Renesas RZ/N1 A5PSW switch");
114 MODULE_LICENSE("GPL v2");
115 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_A5PSW, A5PSW_NAME);
116 module_dsa_tag_driver(a5psw_netdev_ops);
117
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