summaryrefslogtreecommitdiff
path: root/net/dsa/tag_brcm.c
blob: e934dace39227409b9d972b5bbb6cbec8605ac66 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
// SPDX-License-Identifier: GPL-2.0+
/*
 * Broadcom tag support
 *
 * Copyright (C) 2014 Broadcom Corporation
 */

#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/slab.h>

#include "dsa_priv.h"

/* This tag length is 4 bytes, older ones were 6 bytes, we do not
 * handle them
 */
#define BRCM_TAG_LEN	4

/* Tag is constructed and desconstructed using byte by byte access
 * because the tag is placed after the MAC Source Address, which does
 * not make it 4-bytes aligned, so this might cause unaligned accesses
 * on most systems where this is used.
 */

/* Ingress and egress opcodes */
#define BRCM_OPCODE_SHIFT	5
#define BRCM_OPCODE_MASK	0x7

/* Ingress fields */
/* 1st byte in the tag */
#define BRCM_IG_TC_SHIFT	2
#define BRCM_IG_TC_MASK		0x7
/* 2nd byte in the tag */
#define BRCM_IG_TE_MASK		0x3
#define BRCM_IG_TS_SHIFT	7
/* 3rd byte in the tag */
#define BRCM_IG_DSTMAP2_MASK	1
#define BRCM_IG_DSTMAP1_MASK	0xff

/* Egress fields */

/* 2nd byte in the tag */
#define BRCM_EG_CID_MASK	0xff

/* 3rd byte in the tag */
#define BRCM_EG_RC_MASK		0xff
#define  BRCM_EG_RC_RSVD	(3 << 6)
#define  BRCM_EG_RC_EXCEPTION	(1 << 5)
#define  BRCM_EG_RC_PROT_SNOOP	(1 << 4)
#define  BRCM_EG_RC_PROT_TERM	(1 << 3)
#define  BRCM_EG_RC_SWITCH	(1 << 2)
#define  BRCM_EG_RC_MAC_LEARN	(1 << 1)
#define  BRCM_EG_RC_MIRROR	(1 << 0)
#define BRCM_EG_TC_SHIFT	5
#define BRCM_EG_TC_MASK		0x7
#define BRCM_EG_PID_MASK	0x1f

#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) || \
	IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)

static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
					struct net_device *dev,
					unsigned int offset)
{
	struct dsa_port *dp = dsa_slave_to_port(dev);
	u16 queue = skb_get_queue_mapping(skb);
	u8 *brcm_tag;

	/* The Ethernet switch we are interfaced with needs packets to be at
	 * least 64 bytes (including FCS) otherwise they will be discarded when
	 * they enter the switch port logic. When Broadcom tags are enabled, we
	 * need to make sure that packets are at least 68 bytes
	 * (including FCS and tag) because the length verification is done after
	 * the Broadcom tag is stripped off the ingress packet.
	 *
	 * Let dsa_slave_xmit() free the SKB
	 */
	if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
		return NULL;

	skb_push(skb, BRCM_TAG_LEN);

	if (offset)
		memmove(skb->data, skb->data + BRCM_TAG_LEN, offset);

	brcm_tag = skb->data + offset;

	/* Set the ingress opcode, traffic class, tag enforcment is
	 * deprecated
	 */
	brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
		       ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
	brcm_tag[1] = 0;
	brcm_tag[2] = 0;
	if (dp->index == 8)
		brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
	brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;

	/* Now tell the master network device about the desired output queue
	 * as well
	 */
	skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));

	return skb;
}

/* Frames with this tag have one of these two layouts:
 * -----------------------------------
 * | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM
 * -----------------------------------
 * -----------------------------------
 * | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND
 * -----------------------------------
 * In both cases, at receive time, skb->data points 2 bytes before the actual
 * Ethernet type field and we have an offset of 4bytes between where skb->data
 * and where the payload starts. So the same low-level receive function can be
 * used.
 */
static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
				       struct net_device *dev,
				       struct packet_type *pt,
				       unsigned int offset)
{
	int source_port;
	u8 *brcm_tag;

	if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
		return NULL;

	brcm_tag = skb->data - offset;

	/* The opcode should never be different than 0b000 */
	if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
		return NULL;

	/* We should never see a reserved reason code without knowing how to
	 * handle it
	 */
	if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
		return NULL;

	/* Locate which port this is coming from */
	source_port = brcm_tag[3] & BRCM_EG_PID_MASK;

	skb->dev = dsa_master_find_slave(dev, 0, source_port);
	if (!skb->dev)
		return NULL;

	/* Remove Broadcom tag and update checksum */
	skb_pull_rcsum(skb, BRCM_TAG_LEN);

	skb->offload_fwd_mark = 1;

	return skb;
}
#endif

#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
				     struct net_device *dev)
{
	/* Build the tag after the MAC Source Address */
	return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
}


static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
				    struct packet_type *pt)
{
	struct sk_buff *nskb;

	/* skb->data points to the EtherType, the tag is right before it */
	nskb = brcm_tag_rcv_ll(skb, dev, pt, 2);
	if (!nskb)
		return nskb;

	/* Move the Ethernet DA and SA */
	memmove(nskb->data - ETH_HLEN,
		nskb->data - ETH_HLEN - BRCM_TAG_LEN,
		2 * ETH_ALEN);

	return nskb;
}

static const struct dsa_device_ops brcm_netdev_ops = {
	.name	= "brcm",
	.proto	= DSA_TAG_PROTO_BRCM,
	.xmit	= brcm_tag_xmit,
	.rcv	= brcm_tag_rcv,
	.overhead = BRCM_TAG_LEN,
};

DSA_TAG_DRIVER(brcm_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
#endif

#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
					     struct net_device *dev)
{
	/* tag is prepended to the packet */
	return brcm_tag_xmit_ll(skb, dev, 0);
}

static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
					    struct net_device *dev,
					    struct packet_type *pt)
{
	/* tag is prepended to the packet */
	return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
}

static const struct dsa_device_ops brcm_prepend_netdev_ops = {
	.name	= "brcm-prepend",
	.proto	= DSA_TAG_PROTO_BRCM_PREPEND,
	.xmit	= brcm_tag_xmit_prepend,
	.rcv	= brcm_tag_rcv_prepend,
	.overhead = BRCM_TAG_LEN,
};

DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND);
#endif

static struct dsa_tag_driver *dsa_tag_driver_array[] =	{
#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
	&DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
#endif
#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
	&DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
#endif
};

module_dsa_tag_drivers(dsa_tag_driver_array);

MODULE_LICENSE("GPL");