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 #define LAN9303_MAX_PORTS 3 43 44 static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev) 45 { 46 struct dsa_slave_priv *p = netdev_priv(dev); 47 u16 *lan9303_tag; 48 49 /* insert a special VLAN tag between the MAC addresses 50 * and the current ethertype field. 51 */ 52 if (skb_cow_head(skb, LAN9303_TAG_LEN) < 0) { 53 dev_dbg(&dev->dev, 54 "Cannot make room for the special tag. Dropping packet\n"); 55 return NULL; 56 } 57 58 /* provide 'LAN9303_TAG_LEN' bytes additional space */ 59 skb_push(skb, LAN9303_TAG_LEN); 60 61 /* make room between MACs and Ether-Type */ 62 memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN); 63 64 lan9303_tag = (u16 *)(skb->data + 2 * ETH_ALEN); 65 lan9303_tag[0] = htons(ETH_P_8021Q); 66 lan9303_tag[1] = htons(p->dp->index | BIT(4)); 67 68 return skb; 69 } 70 71 static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev, 72 struct packet_type *pt, struct net_device *orig_dev) 73 { 74 u16 *lan9303_tag; 75 struct dsa_switch_tree *dst = dev->dsa_ptr; 76 struct dsa_switch *ds; 77 unsigned int source_port; 78 79 ds = dst->ds[0]; 80 81 if (unlikely(!ds)) { 82 dev_warn_ratelimited(&dev->dev, "Dropping packet, due to missing DSA switch device\n"); 83 return NULL; 84 } 85 86 if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) { 87 dev_warn_ratelimited(&dev->dev, 88 "Dropping packet, cannot pull\n"); 89 return NULL; 90 } 91 92 /* '->data' points into the middle of our special VLAN tag information: 93 * 94 * ~ MAC src | 0x81 | 0x00 | 0xyy | 0xzz | ether type 95 * ^ 96 * ->data 97 */ 98 lan9303_tag = (u16 *)(skb->data - 2); 99 100 if (lan9303_tag[0] != htons(ETH_P_8021Q)) { 101 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n"); 102 return NULL; 103 } 104 105 source_port = ntohs(lan9303_tag[1]) & 0x3; 106 107 if (source_port >= LAN9303_MAX_PORTS) { 108 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n"); 109 return NULL; 110 } 111 112 if (!ds->ports[source_port].netdev) { 113 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid netdev or device\n"); 114 return NULL; 115 } 116 117 /* remove the special VLAN tag between the MAC addresses 118 * and the current ethertype field. 119 */ 120 skb_pull_rcsum(skb, 2 + 2); 121 memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN), 122 2 * ETH_ALEN); 123 124 /* forward the packet to the dedicated interface */ 125 skb->dev = ds->ports[source_port].netdev; 126 127 return skb; 128 } 129 130 const struct dsa_device_ops lan9303_netdev_ops = { 131 .xmit = lan9303_xmit, 132 .rcv = lan9303_rcv, 133 }; 134