1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2017 Pengutronix, Juergen Borleis <jbe@pengutronix.de> 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 "dsa_priv.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_TAG_LEN 4 34 # define LAN9303_TAG_TX_USE_ALR BIT(3) 35 # define LAN9303_TAG_TX_STP_OVERRIDE BIT(4) 36 # define LAN9303_TAG_RX_IGMP BIT(3) 37 # define LAN9303_TAG_RX_STP BIT(4) 38 # define LAN9303_TAG_RX_TRAPPED_TO_CPU (LAN9303_TAG_RX_IGMP | \ 39 LAN9303_TAG_RX_STP) 40 41 /* Decide whether to transmit using ALR lookup, or transmit directly to 42 * port using tag. ALR learning is performed only when using ALR lookup. 43 * If the two external ports are bridged and the frame is unicast, 44 * then use ALR lookup to allow ALR learning on CPU port. 45 * Otherwise transmit directly to port with STP state override. 46 * See also: lan9303_separate_ports() and lan9303.pdf 6.4.10.1 47 */ 48 static int lan9303_xmit_use_arl(struct dsa_port *dp, u8 *dest_addr) 49 { 50 struct lan9303 *chip = dp->ds->priv; 51 52 return chip->is_bridged && !is_multicast_ether_addr(dest_addr); 53 } 54 55 static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev) 56 { 57 struct dsa_port *dp = dsa_slave_to_port(dev); 58 __be16 *lan9303_tag; 59 u16 tag; 60 61 /* provide 'LAN9303_TAG_LEN' bytes additional space */ 62 skb_push(skb, LAN9303_TAG_LEN); 63 64 /* make room between MACs and Ether-Type */ 65 memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN); 66 67 lan9303_tag = (__be16 *)(skb->data + 2 * ETH_ALEN); 68 tag = lan9303_xmit_use_arl(dp, skb->data) ? 69 LAN9303_TAG_TX_USE_ALR : 70 dp->index | LAN9303_TAG_TX_STP_OVERRIDE; 71 lan9303_tag[0] = htons(ETH_P_8021Q); 72 lan9303_tag[1] = htons(tag); 73 74 return skb; 75 } 76 77 static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev, 78 struct packet_type *pt) 79 { 80 __be16 *lan9303_tag; 81 u16 lan9303_tag1; 82 unsigned int source_port; 83 84 if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) { 85 dev_warn_ratelimited(&dev->dev, 86 "Dropping packet, cannot pull\n"); 87 return NULL; 88 } 89 90 /* '->data' points into the middle of our special VLAN tag information: 91 * 92 * ~ MAC src | 0x81 | 0x00 | 0xyy | 0xzz | ether type 93 * ^ 94 * ->data 95 */ 96 lan9303_tag = (__be16 *)(skb->data - 2); 97 98 if (lan9303_tag[0] != htons(ETH_P_8021Q)) { 99 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n"); 100 return NULL; 101 } 102 103 lan9303_tag1 = ntohs(lan9303_tag[1]); 104 source_port = lan9303_tag1 & 0x3; 105 106 skb->dev = dsa_master_find_slave(dev, 0, source_port); 107 if (!skb->dev) { 108 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n"); 109 return NULL; 110 } 111 112 /* remove the special VLAN tag between the MAC addresses 113 * and the current ethertype field. 114 */ 115 skb_pull_rcsum(skb, 2 + 2); 116 memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN), 117 2 * ETH_ALEN); 118 skb->offload_fwd_mark = !(lan9303_tag1 & LAN9303_TAG_RX_TRAPPED_TO_CPU); 119 120 return skb; 121 } 122 123 static const struct dsa_device_ops lan9303_netdev_ops = { 124 .name = "lan9303", 125 .proto = DSA_TAG_PROTO_LAN9303, 126 .xmit = lan9303_xmit, 127 .rcv = lan9303_rcv, 128 .needed_headroom = LAN9303_TAG_LEN, 129 }; 130 131 MODULE_LICENSE("GPL"); 132 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_LAN9303); 133 134 module_dsa_tag_driver(lan9303_netdev_ops); 135