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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2017 Pengutronix, Juergen Borleis <[email protected]>
4 */
5#include <linux/dsa/lan9303.h>
6#include <linux/etherdevice.h>
7#include <linux/list.h>
8#include <linux/slab.h>
9
10#include "tag.h"
11
12/* To define the outgoing port and to discover the incoming port a regular
13 * VLAN tag is used by the LAN9303. But its VID meaning is 'special':
14 *
15 * Dest MAC Src MAC TAG Type
16 * ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 | 1 2 |...
17 * |<------->|
18 * TAG:
19 * |<------------->|
20 * | 1 2 | 3 4 |
21 * TPID VID
22 * 0x8100
23 *
24 * VID bit 3 indicates a request for an ALR lookup.
25 *
26 * If VID bit 3 is zero, then bits 0 and 1 specify the destination port
27 * (0, 1, 2) or broadcast (3) or the source port (1, 2).
28 *
29 * VID bit 4 is used to specify if the STP port state should be overridden.
30 * Required when no forwarding between the external ports should happen.
31 */
32
33#define LAN9303_NAME "lan9303"
34
35#define LAN9303_TAG_LEN 4
36# define LAN9303_TAG_TX_USE_ALR BIT(3)
37# define LAN9303_TAG_TX_STP_OVERRIDE BIT(4)
38# define LAN9303_TAG_RX_IGMP BIT(3)
39# define LAN9303_TAG_RX_STP BIT(4)
40# define LAN9303_TAG_RX_TRAPPED_TO_CPU (LAN9303_TAG_RX_IGMP | \
41 LAN9303_TAG_RX_STP)
42
43/* Decide whether to transmit using ALR lookup, or transmit directly to
44 * port using tag. ALR learning is performed only when using ALR lookup.
45 * If the two external ports are bridged and the frame is unicast,
46 * then use ALR lookup to allow ALR learning on CPU port.
47 * Otherwise transmit directly to port with STP state override.
48 * See also: lan9303_separate_ports() and lan9303.pdf 6.4.10.1
49 */
50static int lan9303_xmit_use_arl(struct dsa_port *dp, u8 *dest_addr)
51{
52 struct lan9303 *chip = dp->ds->priv;
53
54 return chip->is_bridged && !is_multicast_ether_addr(dest_addr);
55}
56
57static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
58{
59 struct dsa_port *dp = dsa_user_to_port(dev);
60 __be16 *lan9303_tag;
61 u16 tag;
62
63 /* provide 'LAN9303_TAG_LEN' bytes additional space */
64 skb_push(skb, LAN9303_TAG_LEN);
65
66 /* make room between MACs and Ether-Type */
67 dsa_alloc_etype_header(skb, LAN9303_TAG_LEN);
68
69 lan9303_tag = dsa_etype_header_pos_tx(skb);
70
71 tag = lan9303_xmit_use_arl(dp, skb->data) ?
72 LAN9303_TAG_TX_USE_ALR :
73 dp->index | LAN9303_TAG_TX_STP_OVERRIDE;
74 lan9303_tag[0] = htons(ETH_P_8021Q);
75 lan9303_tag[1] = htons(tag);
76
77 return skb;
78}
79
80static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev)
81{
82 u16 lan9303_tag1;
83 unsigned int source_port;
84
85 if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
86 dev_warn_ratelimited(&dev->dev,
87 "Dropping packet, cannot pull\n");
88 kfree_skb(skb);
89 return NULL;
90 }
91
92 if (skb_vlan_tag_present(skb)) {
93 lan9303_tag1 = skb_vlan_tag_get(skb);
94 __vlan_hwaccel_clear_tag(skb);
95 } else {
96 skb_push_rcsum(skb, ETH_HLEN);
97 __skb_vlan_pop(skb, &lan9303_tag1);
98 skb_pull_rcsum(skb, ETH_HLEN);
99 }
100
101 source_port = lan9303_tag1 & 0x3;
102
103 skb->dev = dsa_conduit_find_user(dev, 0, source_port);
104 if (!skb->dev) {
105 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n");
106 kfree_skb(skb);
107 return NULL;
108 }
109
110 if (!(lan9303_tag1 & LAN9303_TAG_RX_TRAPPED_TO_CPU))
111 dsa_default_offload_fwd_mark(skb);
112
113 return skb;
114}
115
116static const struct dsa_device_ops lan9303_netdev_ops = {
117 .name = LAN9303_NAME,
118 .proto = DSA_TAG_PROTO_LAN9303,
119 .xmit = lan9303_xmit,
120 .rcv = lan9303_rcv,
121 .needed_headroom = LAN9303_TAG_LEN,
122};
123
124MODULE_DESCRIPTION("DSA tag driver for SMSC/Microchip LAN9303 family of switches");
125MODULE_LICENSE("GPL");
126MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_LAN9303, LAN9303_NAME);
127
128module_dsa_tag_driver(lan9303_netdev_ops);