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/dsa/lan9303.h> 15 #include <linux/etherdevice.h> 16 #include <linux/list.h> 17 #include <linux/slab.h> 18 19 #include "dsa_priv.h" 20 21 /* To define the outgoing port and to discover the incoming port a regular 22 * VLAN tag is used by the LAN9303. But its VID meaning is 'special': 23 * 24 * Dest MAC Src MAC TAG Type 25 * ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 | 1 2 |... 26 * |<------->| 27 * TAG: 28 * |<------------->| 29 * | 1 2 | 3 4 | 30 * TPID VID 31 * 0x8100 32 * 33 * VID bit 3 indicates a request for an ALR lookup. 34 * 35 * If VID bit 3 is zero, then bits 0 and 1 specify the destination port 36 * (0, 1, 2) or broadcast (3) or the source port (1, 2). 37 * 38 * VID bit 4 is used to specify if the STP port state should be overridden. 39 * Required when no forwarding between the external ports should happen. 40 */ 41 42 #define LAN9303_TAG_LEN 4 43 # define LAN9303_TAG_TX_USE_ALR BIT(3) 44 # define LAN9303_TAG_TX_STP_OVERRIDE BIT(4) 45 # define LAN9303_TAG_RX_IGMP BIT(3) 46 # define LAN9303_TAG_RX_STP BIT(4) 47 # define LAN9303_TAG_RX_TRAPPED_TO_CPU (LAN9303_TAG_RX_IGMP | \ 48 LAN9303_TAG_RX_STP) 49 50 /* Decide whether to transmit using ALR lookup, or transmit directly to 51 * port using tag. ALR learning is performed only when using ALR lookup. 52 * If the two external ports are bridged and the frame is unicast, 53 * then use ALR lookup to allow ALR learning on CPU port. 54 * Otherwise transmit directly to port with STP state override. 55 * See also: lan9303_separate_ports() and lan9303.pdf 6.4.10.1 56 */ 57 static int lan9303_xmit_use_arl(struct dsa_port *dp, u8 *dest_addr) 58 { 59 struct lan9303 *chip = dp->ds->priv; 60 61 return chip->is_bridged && !is_multicast_ether_addr(dest_addr); 62 } 63 64 static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev) 65 { 66 struct dsa_port *dp = dsa_slave_to_port(dev); 67 u16 *lan9303_tag; 68 69 /* insert a special VLAN tag between the MAC addresses 70 * and the current ethertype field. 71 */ 72 if (skb_cow_head(skb, LAN9303_TAG_LEN) < 0) { 73 dev_dbg(&dev->dev, 74 "Cannot make room for the special tag. Dropping packet\n"); 75 return NULL; 76 } 77 78 /* provide 'LAN9303_TAG_LEN' bytes additional space */ 79 skb_push(skb, LAN9303_TAG_LEN); 80 81 /* make room between MACs and Ether-Type */ 82 memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN); 83 84 lan9303_tag = (u16 *)(skb->data + 2 * ETH_ALEN); 85 lan9303_tag[0] = htons(ETH_P_8021Q); 86 lan9303_tag[1] = lan9303_xmit_use_arl(dp, skb->data) ? 87 LAN9303_TAG_TX_USE_ALR : 88 dp->index | LAN9303_TAG_TX_STP_OVERRIDE; 89 lan9303_tag[1] = htons(lan9303_tag[1]); 90 91 return skb; 92 } 93 94 static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev, 95 struct packet_type *pt) 96 { 97 u16 *lan9303_tag; 98 u16 lan9303_tag1; 99 unsigned int source_port; 100 101 if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) { 102 dev_warn_ratelimited(&dev->dev, 103 "Dropping packet, cannot pull\n"); 104 return NULL; 105 } 106 107 /* '->data' points into the middle of our special VLAN tag information: 108 * 109 * ~ MAC src | 0x81 | 0x00 | 0xyy | 0xzz | ether type 110 * ^ 111 * ->data 112 */ 113 lan9303_tag = (u16 *)(skb->data - 2); 114 115 if (lan9303_tag[0] != htons(ETH_P_8021Q)) { 116 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n"); 117 return NULL; 118 } 119 120 lan9303_tag1 = ntohs(lan9303_tag[1]); 121 source_port = lan9303_tag1 & 0x3; 122 123 skb->dev = dsa_master_find_slave(dev, 0, source_port); 124 if (!skb->dev) { 125 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n"); 126 return NULL; 127 } 128 129 /* remove the special VLAN tag between the MAC addresses 130 * and the current ethertype field. 131 */ 132 skb_pull_rcsum(skb, 2 + 2); 133 memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN), 134 2 * ETH_ALEN); 135 skb->offload_fwd_mark = !(lan9303_tag1 & LAN9303_TAG_RX_TRAPPED_TO_CPU); 136 137 return skb; 138 } 139 140 const struct dsa_device_ops lan9303_netdev_ops = { 141 .xmit = lan9303_xmit, 142 .rcv = lan9303_rcv, 143 }; 144