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
brcm_tag_xmit(struct sk_buff * skb,struct net_device * dev)62 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev)
63 {
64 struct dsa_slave_priv *p = netdev_priv(dev);
65 u16 queue = skb_get_queue_mapping(skb);
66 u8 *brcm_tag;
67
68 if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
69 return NULL;
70
71 skb_push(skb, BRCM_TAG_LEN);
72
73 memmove(skb->data, skb->data + BRCM_TAG_LEN, 2 * ETH_ALEN);
74
75 /* Build the tag after the MAC Source Address */
76 brcm_tag = skb->data + 2 * ETH_ALEN;
77
78 /* Set the ingress opcode, traffic class, tag enforcment is
79 * deprecated
80 */
81 brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
82 ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
83 brcm_tag[1] = 0;
84 brcm_tag[2] = 0;
85 if (p->dp->index == 8)
86 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
87 brcm_tag[3] = (1 << p->dp->index) & BRCM_IG_DSTMAP1_MASK;
88
89 return skb;
90 }
91
brcm_tag_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)92 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
93 struct packet_type *pt)
94 {
95 struct dsa_switch_tree *dst = dev->dsa_ptr;
96 struct dsa_port *cpu_dp = dsa_get_cpu_port(dst);
97 struct dsa_switch *ds = cpu_dp->ds;
98 int source_port;
99 u8 *brcm_tag;
100
101 if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
102 return NULL;
103
104 /* skb->data points to the EtherType, the tag is right before it */
105 brcm_tag = skb->data - 2;
106
107 /* The opcode should never be different than 0b000 */
108 if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
109 return NULL;
110
111 /* We should never see a reserved reason code without knowing how to
112 * handle it
113 */
114 if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
115 return NULL;
116
117 /* Locate which port this is coming from */
118 source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
119
120 /* Validate port against switch setup, either the port is totally */
121 if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
122 return NULL;
123
124 if (unlikely(ds->cpu_port_mask & BIT(source_port)))
125 return NULL;
126
127 /* Remove Broadcom tag and update checksum */
128 skb_pull_rcsum(skb, BRCM_TAG_LEN);
129
130 /* Move the Ethernet DA and SA */
131 memmove(skb->data - ETH_HLEN,
132 skb->data - ETH_HLEN - BRCM_TAG_LEN,
133 2 * ETH_ALEN);
134
135 skb->dev = ds->ports[source_port].netdev;
136
137 skb->offload_fwd_mark = 1;
138
139 return skb;
140 }
141
142 const struct dsa_device_ops brcm_netdev_ops = {
143 .xmit = brcm_tag_xmit,
144 .rcv = brcm_tag_rcv,
145 };
146