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 dsa_alloc_etype_header(skb, LAN9303_TAG_LEN); 66 67 lan9303_tag = dsa_etype_header_pos_tx(skb); 68 69 tag = lan9303_xmit_use_arl(dp, skb->data) ? 70 LAN9303_TAG_TX_USE_ALR : 71 dp->index | LAN9303_TAG_TX_STP_OVERRIDE; 72 lan9303_tag[0] = htons(ETH_P_8021Q); 73 lan9303_tag[1] = htons(tag); 74 75 return skb; 76 } 77 78 static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev) 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 lan9303_tag = dsa_etype_header_pos_rx(skb); 91 92 if (lan9303_tag[0] != htons(ETH_P_8021Q)) { 93 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n"); 94 return NULL; 95 } 96 97 lan9303_tag1 = ntohs(lan9303_tag[1]); 98 source_port = lan9303_tag1 & 0x3; 99 100 skb->dev = dsa_master_find_slave(dev, 0, source_port); 101 if (!skb->dev) { 102 dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n"); 103 return NULL; 104 } 105 106 /* remove the special VLAN tag between the MAC addresses 107 * and the current ethertype field. 108 */ 109 skb_pull_rcsum(skb, 2 + 2); 110 111 dsa_strip_etype_header(skb, LAN9303_TAG_LEN); 112 113 if (!(lan9303_tag1 & LAN9303_TAG_RX_TRAPPED_TO_CPU)) 114 dsa_default_offload_fwd_mark(skb); 115 116 return skb; 117 } 118 119 static const struct dsa_device_ops lan9303_netdev_ops = { 120 .name = "lan9303", 121 .proto = DSA_TAG_PROTO_LAN9303, 122 .xmit = lan9303_xmit, 123 .rcv = lan9303_rcv, 124 .needed_headroom = LAN9303_TAG_LEN, 125 }; 126 127 MODULE_LICENSE("GPL"); 128 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_LAN9303); 129 130 module_dsa_tag_driver(lan9303_netdev_ops); 131