1 /* 2 * net/dsa/tag_dsa.c - (Non-ethertype) DSA tagging 3 * Copyright (c) 2008-2009 Marvell Semiconductor 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 */ 10 11 #include <linux/etherdevice.h> 12 #include <linux/list.h> 13 #include <linux/slab.h> 14 #include "dsa_priv.h" 15 16 #define DSA_HLEN 4 17 18 static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev) 19 { 20 struct dsa_slave_priv *p = netdev_priv(dev); 21 u8 *dsa_header; 22 23 /* 24 * Convert the outermost 802.1q tag to a DSA tag for tagged 25 * packets, or insert a DSA tag between the addresses and 26 * the ethertype field for untagged packets. 27 */ 28 if (skb->protocol == htons(ETH_P_8021Q)) { 29 if (skb_cow_head(skb, 0) < 0) 30 goto out_free; 31 32 /* 33 * Construct tagged FROM_CPU DSA tag from 802.1q tag. 34 */ 35 dsa_header = skb->data + 2 * ETH_ALEN; 36 dsa_header[0] = 0x60 | p->parent->index; 37 dsa_header[1] = p->port << 3; 38 39 /* 40 * Move CFI field from byte 2 to byte 1. 41 */ 42 if (dsa_header[2] & 0x10) { 43 dsa_header[1] |= 0x01; 44 dsa_header[2] &= ~0x10; 45 } 46 } else { 47 if (skb_cow_head(skb, DSA_HLEN) < 0) 48 goto out_free; 49 skb_push(skb, DSA_HLEN); 50 51 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN); 52 53 /* 54 * Construct untagged FROM_CPU DSA tag. 55 */ 56 dsa_header = skb->data + 2 * ETH_ALEN; 57 dsa_header[0] = 0x40 | p->parent->index; 58 dsa_header[1] = p->port << 3; 59 dsa_header[2] = 0x00; 60 dsa_header[3] = 0x00; 61 } 62 63 return skb; 64 65 out_free: 66 kfree_skb(skb); 67 return NULL; 68 } 69 70 static int dsa_rcv(struct sk_buff *skb, struct net_device *dev, 71 struct packet_type *pt, struct net_device *orig_dev) 72 { 73 struct dsa_switch_tree *dst = dev->dsa_ptr; 74 struct dsa_switch *ds; 75 u8 *dsa_header; 76 int source_device; 77 int source_port; 78 79 if (unlikely(dst == NULL)) 80 goto out_drop; 81 82 skb = skb_unshare(skb, GFP_ATOMIC); 83 if (skb == NULL) 84 goto out; 85 86 if (unlikely(!pskb_may_pull(skb, DSA_HLEN))) 87 goto out_drop; 88 89 /* 90 * The ethertype field is part of the DSA header. 91 */ 92 dsa_header = skb->data - 2; 93 94 /* 95 * Check that frame type is either TO_CPU or FORWARD. 96 */ 97 if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0) 98 goto out_drop; 99 100 /* 101 * Determine source device and port. 102 */ 103 source_device = dsa_header[0] & 0x1f; 104 source_port = (dsa_header[1] >> 3) & 0x1f; 105 106 /* 107 * Check that the source device exists and that the source 108 * port is a registered DSA port. 109 */ 110 if (source_device >= DSA_MAX_SWITCHES) 111 goto out_drop; 112 113 ds = dst->ds[source_device]; 114 if (!ds) 115 goto out_drop; 116 117 if (source_port >= DSA_MAX_PORTS || !ds->ports[source_port].netdev) 118 goto out_drop; 119 120 /* 121 * Convert the DSA header to an 802.1q header if the 'tagged' 122 * bit in the DSA header is set. If the 'tagged' bit is clear, 123 * delete the DSA header entirely. 124 */ 125 if (dsa_header[0] & 0x20) { 126 u8 new_header[4]; 127 128 /* 129 * Insert 802.1q ethertype and copy the VLAN-related 130 * fields, but clear the bit that will hold CFI (since 131 * DSA uses that bit location for another purpose). 132 */ 133 new_header[0] = (ETH_P_8021Q >> 8) & 0xff; 134 new_header[1] = ETH_P_8021Q & 0xff; 135 new_header[2] = dsa_header[2] & ~0x10; 136 new_header[3] = dsa_header[3]; 137 138 /* 139 * Move CFI bit from its place in the DSA header to 140 * its 802.1q-designated place. 141 */ 142 if (dsa_header[1] & 0x01) 143 new_header[2] |= 0x10; 144 145 /* 146 * Update packet checksum if skb is CHECKSUM_COMPLETE. 147 */ 148 if (skb->ip_summed == CHECKSUM_COMPLETE) { 149 __wsum c = skb->csum; 150 c = csum_add(c, csum_partial(new_header + 2, 2, 0)); 151 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0)); 152 skb->csum = c; 153 } 154 155 memcpy(dsa_header, new_header, DSA_HLEN); 156 } else { 157 /* 158 * Remove DSA tag and update checksum. 159 */ 160 skb_pull_rcsum(skb, DSA_HLEN); 161 memmove(skb->data - ETH_HLEN, 162 skb->data - ETH_HLEN - DSA_HLEN, 163 2 * ETH_ALEN); 164 } 165 166 skb->dev = ds->ports[source_port].netdev; 167 skb_push(skb, ETH_HLEN); 168 skb->pkt_type = PACKET_HOST; 169 skb->protocol = eth_type_trans(skb, skb->dev); 170 171 skb->dev->stats.rx_packets++; 172 skb->dev->stats.rx_bytes += skb->len; 173 174 netif_receive_skb(skb); 175 176 return 0; 177 178 out_drop: 179 kfree_skb(skb); 180 out: 181 return 0; 182 } 183 184 const struct dsa_device_ops dsa_netdev_ops = { 185 .xmit = dsa_xmit, 186 .rcv = dsa_rcv, 187 }; 188