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efd7fe68 LW |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Handler for Realtek 4 byte DSA switch tags | |
4 | * Currently only supports protocol "A" found in RTL8366RB | |
5 | * Copyright (c) 2020 Linus Walleij <linus.walleij@linaro.org> | |
6 | * | |
7 | * This "proprietary tag" header looks like so: | |
8 | * | |
9 | * ------------------------------------------------- | |
10 | * | MAC DA | MAC SA | 0x8899 | 2 bytes tag | Type | | |
11 | * ------------------------------------------------- | |
12 | * | |
13 | * The 2 bytes tag form a 16 bit big endian word. The exact | |
14 | * meaning has been guessed from packet dumps from ingress | |
86dd9868 | 15 | * frames. |
efd7fe68 LW |
16 | */ |
17 | ||
18 | #include <linux/etherdevice.h> | |
19 | #include <linux/bits.h> | |
20 | ||
bd954b82 | 21 | #include "tag.h" |
efd7fe68 | 22 | |
94793a56 VO |
23 | #define RTL4_A_NAME "rtl4a" |
24 | ||
efd7fe68 | 25 | #define RTL4_A_HDR_LEN 4 |
efd7fe68 LW |
26 | #define RTL4_A_PROTOCOL_SHIFT 12 |
27 | /* | |
28 | * 0x1 = Realtek Remote Control protocol (RRCP) | |
29 | * 0x2/0x3 seems to be used for loopback testing | |
30 | * 0x9 = RTL8306 DSA protocol | |
31 | * 0xa = RTL8366RB DSA protocol | |
32 | */ | |
33 | #define RTL4_A_PROTOCOL_RTL8366RB 0xa | |
34 | ||
35 | static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb, | |
36 | struct net_device *dev) | |
37 | { | |
6ca80638 | 38 | struct dsa_port *dp = dsa_user_to_port(dev); |
9eb8bc59 | 39 | __be16 *p; |
86dd9868 | 40 | u8 *tag; |
86dd9868 LW |
41 | u16 out; |
42 | ||
43 | /* Pad out to at least 60 bytes */ | |
9eb8bc59 | 44 | if (unlikely(__skb_put_padto(skb, ETH_ZLEN, false))) |
86dd9868 LW |
45 | return NULL; |
46 | ||
47 | netdev_dbg(dev, "add realtek tag to package to port %d\n", | |
48 | dp->index); | |
49 | skb_push(skb, RTL4_A_HDR_LEN); | |
50 | ||
6bef794d | 51 | dsa_alloc_etype_header(skb, RTL4_A_HDR_LEN); |
a72808b6 | 52 | tag = dsa_etype_header_pos_tx(skb); |
86dd9868 LW |
53 | |
54 | /* Set Ethertype */ | |
9eb8bc59 | 55 | p = (__be16 *)tag; |
8fedaaca | 56 | *p = htons(ETH_P_REALTEK); |
86dd9868 | 57 | |
339133f6 | 58 | out = (RTL4_A_PROTOCOL_RTL8366RB << RTL4_A_PROTOCOL_SHIFT); |
0e90dfa7 LW |
59 | /* The lower bits indicate the port number */ |
60 | out |= BIT(dp->index); | |
61 | ||
9eb8bc59 | 62 | p = (__be16 *)(tag + 2); |
86dd9868 LW |
63 | *p = htons(out); |
64 | ||
efd7fe68 LW |
65 | return skb; |
66 | } | |
67 | ||
68 | static struct sk_buff *rtl4a_tag_rcv(struct sk_buff *skb, | |
29a097b7 | 69 | struct net_device *dev) |
efd7fe68 LW |
70 | { |
71 | u16 protport; | |
72 | __be16 *p; | |
73 | u16 etype; | |
74 | u8 *tag; | |
75 | u8 prot; | |
76 | u8 port; | |
77 | ||
78 | if (unlikely(!pskb_may_pull(skb, RTL4_A_HDR_LEN))) | |
79 | return NULL; | |
80 | ||
5d928ff4 | 81 | tag = dsa_etype_header_pos_rx(skb); |
efd7fe68 LW |
82 | p = (__be16 *)tag; |
83 | etype = ntohs(*p); | |
8fedaaca | 84 | if (etype != ETH_P_REALTEK) { |
efd7fe68 LW |
85 | /* Not custom, just pass through */ |
86 | netdev_dbg(dev, "non-realtek ethertype 0x%04x\n", etype); | |
87 | return skb; | |
88 | } | |
89 | p = (__be16 *)(tag + 2); | |
90 | protport = ntohs(*p); | |
91 | /* The 4 upper bits are the protocol */ | |
92 | prot = (protport >> RTL4_A_PROTOCOL_SHIFT) & 0x0f; | |
93 | if (prot != RTL4_A_PROTOCOL_RTL8366RB) { | |
94 | netdev_err(dev, "unknown realtek protocol 0x%01x\n", prot); | |
95 | return NULL; | |
96 | } | |
97 | port = protport & 0xff; | |
98 | ||
6ca80638 | 99 | skb->dev = dsa_conduit_find_user(dev, 0, port); |
efd7fe68 | 100 | if (!skb->dev) { |
6ca80638 | 101 | netdev_dbg(dev, "could not find user for port %d\n", port); |
efd7fe68 LW |
102 | return NULL; |
103 | } | |
104 | ||
105 | /* Remove RTL4 tag and recalculate checksum */ | |
106 | skb_pull_rcsum(skb, RTL4_A_HDR_LEN); | |
107 | ||
f1dacd7a | 108 | dsa_strip_etype_header(skb, RTL4_A_HDR_LEN); |
efd7fe68 | 109 | |
bea79078 | 110 | dsa_default_offload_fwd_mark(skb); |
efd7fe68 LW |
111 | |
112 | return skb; | |
113 | } | |
114 | ||
efd7fe68 | 115 | static const struct dsa_device_ops rtl4a_netdev_ops = { |
94793a56 | 116 | .name = RTL4_A_NAME, |
efd7fe68 LW |
117 | .proto = DSA_TAG_PROTO_RTL4_A, |
118 | .xmit = rtl4a_tag_xmit, | |
119 | .rcv = rtl4a_tag_rcv, | |
4e500251 | 120 | .needed_headroom = RTL4_A_HDR_LEN, |
efd7fe68 LW |
121 | }; |
122 | module_dsa_tag_driver(rtl4a_netdev_ops); | |
123 | ||
0ed6e952 | 124 | MODULE_DESCRIPTION("DSA tag driver for Realtek 4 byte protocol A tags"); |
efd7fe68 | 125 | MODULE_LICENSE("GPL"); |
94793a56 | 126 | MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL4_A, RTL4_A_NAME); |