tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (C) 2017 Pengutronix, Juergen Borleis <jbe@pengutronix.de>
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * version 2, as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 */
14#include <linux/etherdevice.h>
15#include <linux/list.h>
16#include <linux/slab.h>
17
18#include "dsa_priv.h"
19
20/* To define the outgoing port and to discover the incoming port a regular
21 * VLAN tag is used by the LAN9303. But its VID meaning is 'special':
22 *
23 * Dest MAC Src MAC TAG Type
24 * ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 | 1 2 |...
25 * |<------->|
26 * TAG:
27 * |<------------->|
28 * | 1 2 | 3 4 |
29 * TPID VID
30 * 0x8100
31 *
32 * VID bit 3 indicates a request for an ALR lookup.
33 *
34 * If VID bit 3 is zero, then bits 0 and 1 specify the destination port
35 * (0, 1, 2) or broadcast (3) or the source port (1, 2).
36 *
37 * VID bit 4 is used to specify if the STP port state should be overridden.
38 * Required when no forwarding between the external ports should happen.
39 */
40
41#define LAN9303_TAG_LEN 4
42
43static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
44{
45 struct dsa_slave_priv *p = netdev_priv(dev);
46 u16 *lan9303_tag;
47
48 /* insert a special VLAN tag between the MAC addresses
49 * and the current ethertype field.
50 */
51 if (skb_cow_head(skb, LAN9303_TAG_LEN) < 0) {
52 dev_dbg(&dev->dev,
53 "Cannot make room for the special tag. Dropping packet\n");
54 return NULL;
55 }
56
57 /* provide 'LAN9303_TAG_LEN' bytes additional space */
58 skb_push(skb, LAN9303_TAG_LEN);
59
60 /* make room between MACs and Ether-Type */
61 memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN);
62
63 lan9303_tag = (u16 *)(skb->data + 2 * ETH_ALEN);
64 lan9303_tag[0] = htons(ETH_P_8021Q);
65 lan9303_tag[1] = htons(p->dp->index | BIT(4));
66
67 return skb;
68}
69
70static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
71 struct packet_type *pt)
72{
73 u16 *lan9303_tag;
74 struct dsa_switch_tree *dst = dev->dsa_ptr;
75 struct dsa_switch *ds;
76 unsigned int source_port;
77
78 ds = dst->ds[0];
79
80 if (unlikely(!ds)) {
81 dev_warn_ratelimited(&dev->dev, "Dropping packet, due to missing DSA switch device\n");
82 return NULL;
83 }
84
85 if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
86 dev_warn_ratelimited(&dev->dev,
87 "Dropping packet, cannot pull\n");
88 return NULL;
89 }
90
91 /* '->data' points into the middle of our special VLAN tag information:
92 *
93 * ~ MAC src | 0x81 | 0x00 | 0xyy | 0xzz | ether type
94 * ^
95 * ->data
96 */
97 lan9303_tag = (u16 *)(skb->data - 2);
98
99 if (lan9303_tag[0] != htons(ETH_P_8021Q)) {
100 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n");
101 return NULL;
102 }
103
104 source_port = ntohs(lan9303_tag[1]) & 0x3;
105
106 if (source_port >= ds->num_ports) {
107 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n");
108 return NULL;
109 }
110
111 if (!ds->ports[source_port].netdev) {
112 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid netdev or device\n");
113 return NULL;
114 }
115
116 /* remove the special VLAN tag between the MAC addresses
117 * and the current ethertype field.
118 */
119 skb_pull_rcsum(skb, 2 + 2);
120 memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN),
121 2 * ETH_ALEN);
122
123 /* forward the packet to the dedicated interface */
124 skb->dev = ds->ports[source_port].netdev;
125
126 return skb;
127}
128
129const struct dsa_device_ops lan9303_netdev_ops = {
130 .xmit = lan9303_xmit,
131 .rcv = lan9303_rcv,
132};