tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Broadcom tag support
3 *
4 * Copyright (C) 2014 Broadcom Corporation
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 */
11
12#include <linux/etherdevice.h>
13#include <linux/list.h>
14#include <linux/slab.h>
15
16#include "dsa_priv.h"
17
18/* This tag length is 4 bytes, older ones were 6 bytes, we do not
19 * handle them
20 */
21#define BRCM_TAG_LEN 4
22
23/* Tag is constructed and desconstructed using byte by byte access
24 * because the tag is placed after the MAC Source Address, which does
25 * not make it 4-bytes aligned, so this might cause unaligned accesses
26 * on most systems where this is used.
27 */
28
29/* Ingress and egress opcodes */
30#define BRCM_OPCODE_SHIFT 5
31#define BRCM_OPCODE_MASK 0x7
32
33/* Ingress fields */
34/* 1st byte in the tag */
35#define BRCM_IG_TC_SHIFT 2
36#define BRCM_IG_TC_MASK 0x7
37/* 2nd byte in the tag */
38#define BRCM_IG_TE_MASK 0x3
39#define BRCM_IG_TS_SHIFT 7
40/* 3rd byte in the tag */
41#define BRCM_IG_DSTMAP2_MASK 1
42#define BRCM_IG_DSTMAP1_MASK 0xff
43
44/* Egress fields */
45
46/* 2nd byte in the tag */
47#define BRCM_EG_CID_MASK 0xff
48
49/* 3rd byte in the tag */
50#define BRCM_EG_RC_MASK 0xff
51#define BRCM_EG_RC_RSVD (3 << 6)
52#define BRCM_EG_RC_EXCEPTION (1 << 5)
53#define BRCM_EG_RC_PROT_SNOOP (1 << 4)
54#define BRCM_EG_RC_PROT_TERM (1 << 3)
55#define BRCM_EG_RC_SWITCH (1 << 2)
56#define BRCM_EG_RC_MAC_LEARN (1 << 1)
57#define BRCM_EG_RC_MIRROR (1 << 0)
58#define BRCM_EG_TC_SHIFT 5
59#define BRCM_EG_TC_MASK 0x7
60#define BRCM_EG_PID_MASK 0x1f
61
62static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
63 struct net_device *dev,
64 unsigned int offset)
65{
66 struct dsa_port *dp = dsa_slave_to_port(dev);
67 u16 queue = skb_get_queue_mapping(skb);
68 u8 *brcm_tag;
69
70 if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
71 return NULL;
72
73 /* The Ethernet switch we are interfaced with needs packets to be at
74 * least 64 bytes (including FCS) otherwise they will be discarded when
75 * they enter the switch port logic. When Broadcom tags are enabled, we
76 * need to make sure that packets are at least 68 bytes
77 * (including FCS and tag) because the length verification is done after
78 * the Broadcom tag is stripped off the ingress packet.
79 *
80 * Let dsa_slave_xmit() free the SKB
81 */
82 if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
83 return NULL;
84
85 skb_push(skb, BRCM_TAG_LEN);
86
87 if (offset)
88 memmove(skb->data, skb->data + BRCM_TAG_LEN, offset);
89
90 brcm_tag = skb->data + offset;
91
92 /* Set the ingress opcode, traffic class, tag enforcment is
93 * deprecated
94 */
95 brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
96 ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
97 brcm_tag[1] = 0;
98 brcm_tag[2] = 0;
99 if (dp->index == 8)
100 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
101 brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;
102
103 /* Now tell the master network device about the desired output queue
104 * as well
105 */
106 skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));
107
108 return skb;
109}
110
111static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
112 struct net_device *dev,
113 struct packet_type *pt,
114 unsigned int offset)
115{
116 int source_port;
117 u8 *brcm_tag;
118
119 if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
120 return NULL;
121
122 brcm_tag = skb->data - offset;
123
124 /* The opcode should never be different than 0b000 */
125 if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
126 return NULL;
127
128 /* We should never see a reserved reason code without knowing how to
129 * handle it
130 */
131 if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
132 return NULL;
133
134 /* Locate which port this is coming from */
135 source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
136
137 skb->dev = dsa_master_find_slave(dev, 0, source_port);
138 if (!skb->dev)
139 return NULL;
140
141 /* Remove Broadcom tag and update checksum */
142 skb_pull_rcsum(skb, BRCM_TAG_LEN);
143
144 return skb;
145}
146
147#ifdef CONFIG_NET_DSA_TAG_BRCM
148static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
149 struct net_device *dev)
150{
151 /* Build the tag after the MAC Source Address */
152 return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
153}
154
155
156static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
157 struct packet_type *pt)
158{
159 struct sk_buff *nskb;
160
161 /* skb->data points to the EtherType, the tag is right before it */
162 nskb = brcm_tag_rcv_ll(skb, dev, pt, 2);
163 if (!nskb)
164 return nskb;
165
166 /* Move the Ethernet DA and SA */
167 memmove(nskb->data - ETH_HLEN,
168 nskb->data - ETH_HLEN - BRCM_TAG_LEN,
169 2 * ETH_ALEN);
170
171 return nskb;
172}
173
174const struct dsa_device_ops brcm_netdev_ops = {
175 .xmit = brcm_tag_xmit,
176 .rcv = brcm_tag_rcv,
177};
178#endif
179
180#ifdef CONFIG_NET_DSA_TAG_BRCM_PREPEND
181static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
182 struct net_device *dev)
183{
184 /* tag is prepended to the packet */
185 return brcm_tag_xmit_ll(skb, dev, 0);
186}
187
188static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
189 struct net_device *dev,
190 struct packet_type *pt)
191{
192 /* tag is prepended to the packet */
193 return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
194}
195
196const struct dsa_device_ops brcm_prepend_netdev_ops = {
197 .xmit = brcm_tag_xmit_prepend,
198 .rcv = brcm_tag_rcv_prepend,
199};
200#endif