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 >= dst->pd->nr_chips) 111 goto out_drop; 112 ds = dst->ds[source_device]; 113 if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL) 114 goto out_drop; 115 116 /* 117 * Convert the DSA header to an 802.1q header if the 'tagged' 118 * bit in the DSA header is set. If the 'tagged' bit is clear, 119 * delete the DSA header entirely. 120 */ 121 if (dsa_header[0] & 0x20) { 122 u8 new_header[4]; 123 124 /* 125 * Insert 802.1q ethertype and copy the VLAN-related 126 * fields, but clear the bit that will hold CFI (since 127 * DSA uses that bit location for another purpose). 128 */ 129 new_header[0] = (ETH_P_8021Q >> 8) & 0xff; 130 new_header[1] = ETH_P_8021Q & 0xff; 131 new_header[2] = dsa_header[2] & ~0x10; 132 new_header[3] = dsa_header[3]; 133 134 /* 135 * Move CFI bit from its place in the DSA header to 136 * its 802.1q-designated place. 137 */ 138 if (dsa_header[1] & 0x01) 139 new_header[2] |= 0x10; 140 141 /* 142 * Update packet checksum if skb is CHECKSUM_COMPLETE. 143 */ 144 if (skb->ip_summed == CHECKSUM_COMPLETE) { 145 __wsum c = skb->csum; 146 c = csum_add(c, csum_partial(new_header + 2, 2, 0)); 147 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0)); 148 skb->csum = c; 149 } 150 151 memcpy(dsa_header, new_header, DSA_HLEN); 152 } else { 153 /* 154 * Remove DSA tag and update checksum. 155 */ 156 skb_pull_rcsum(skb, DSA_HLEN); 157 memmove(skb->data - ETH_HLEN, 158 skb->data - ETH_HLEN - DSA_HLEN, 159 2 * ETH_ALEN); 160 } 161 162 skb->dev = ds->ports[source_port]; 163 skb_push(skb, ETH_HLEN); 164 skb->pkt_type = PACKET_HOST; 165 skb->protocol = eth_type_trans(skb, skb->dev); 166 167 skb->dev->stats.rx_packets++; 168 skb->dev->stats.rx_bytes += skb->len; 169 170 netif_receive_skb(skb); 171 172 return 0; 173 174 out_drop: 175 kfree_skb(skb); 176 out: 177 return 0; 178 } 179 180 const struct dsa_device_ops dsa_netdev_ops = { 181 .xmit = dsa_xmit, 182 .rcv = dsa_rcv, 183 }; 184