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 15 #include "dsa_priv.h" 16 17 #define DSA_HLEN 4 18 19 static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev) 20 { 21 struct dsa_slave_priv *p = netdev_priv(dev); 22 u8 *dsa_header; 23 24 /* 25 * Convert the outermost 802.1q tag to a DSA tag for tagged 26 * packets, or insert a DSA tag between the addresses and 27 * the ethertype field for untagged packets. 28 */ 29 if (skb->protocol == htons(ETH_P_8021Q)) { 30 if (skb_cow_head(skb, 0) < 0) 31 return NULL; 32 33 /* 34 * Construct tagged FROM_CPU DSA tag from 802.1q tag. 35 */ 36 dsa_header = skb->data + 2 * ETH_ALEN; 37 dsa_header[0] = 0x60 | p->dp->ds->index; 38 dsa_header[1] = p->dp->index << 3; 39 40 /* 41 * Move CFI field from byte 2 to byte 1. 42 */ 43 if (dsa_header[2] & 0x10) { 44 dsa_header[1] |= 0x01; 45 dsa_header[2] &= ~0x10; 46 } 47 } else { 48 if (skb_cow_head(skb, DSA_HLEN) < 0) 49 return NULL; 50 skb_push(skb, DSA_HLEN); 51 52 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN); 53 54 /* 55 * Construct untagged FROM_CPU DSA tag. 56 */ 57 dsa_header = skb->data + 2 * ETH_ALEN; 58 dsa_header[0] = 0x40 | p->dp->ds->index; 59 dsa_header[1] = p->dp->index << 3; 60 dsa_header[2] = 0x00; 61 dsa_header[3] = 0x00; 62 } 63 64 return skb; 65 } 66 67 static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev, 68 struct packet_type *pt) 69 { 70 struct dsa_switch_tree *dst = dev->dsa_ptr; 71 struct dsa_switch *ds; 72 u8 *dsa_header; 73 int source_device; 74 int source_port; 75 76 if (unlikely(!pskb_may_pull(skb, DSA_HLEN))) 77 return NULL; 78 79 /* 80 * The ethertype field is part of the DSA header. 81 */ 82 dsa_header = skb->data - 2; 83 84 /* 85 * Check that frame type is either TO_CPU or FORWARD. 86 */ 87 if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0) 88 return NULL; 89 90 /* 91 * Determine source device and port. 92 */ 93 source_device = dsa_header[0] & 0x1f; 94 source_port = (dsa_header[1] >> 3) & 0x1f; 95 96 /* 97 * Check that the source device exists and that the source 98 * port is a registered DSA port. 99 */ 100 if (source_device >= DSA_MAX_SWITCHES) 101 return NULL; 102 103 ds = dst->ds[source_device]; 104 if (!ds) 105 return NULL; 106 107 if (source_port >= ds->num_ports || !ds->ports[source_port].netdev) 108 return NULL; 109 110 /* 111 * Convert the DSA header to an 802.1q header if the 'tagged' 112 * bit in the DSA header is set. If the 'tagged' bit is clear, 113 * delete the DSA header entirely. 114 */ 115 if (dsa_header[0] & 0x20) { 116 u8 new_header[4]; 117 118 /* 119 * Insert 802.1q ethertype and copy the VLAN-related 120 * fields, but clear the bit that will hold CFI (since 121 * DSA uses that bit location for another purpose). 122 */ 123 new_header[0] = (ETH_P_8021Q >> 8) & 0xff; 124 new_header[1] = ETH_P_8021Q & 0xff; 125 new_header[2] = dsa_header[2] & ~0x10; 126 new_header[3] = dsa_header[3]; 127 128 /* 129 * Move CFI bit from its place in the DSA header to 130 * its 802.1q-designated place. 131 */ 132 if (dsa_header[1] & 0x01) 133 new_header[2] |= 0x10; 134 135 /* 136 * Update packet checksum if skb is CHECKSUM_COMPLETE. 137 */ 138 if (skb->ip_summed == CHECKSUM_COMPLETE) { 139 __wsum c = skb->csum; 140 c = csum_add(c, csum_partial(new_header + 2, 2, 0)); 141 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0)); 142 skb->csum = c; 143 } 144 145 memcpy(dsa_header, new_header, DSA_HLEN); 146 } else { 147 /* 148 * Remove DSA tag and update checksum. 149 */ 150 skb_pull_rcsum(skb, DSA_HLEN); 151 memmove(skb->data - ETH_HLEN, 152 skb->data - ETH_HLEN - DSA_HLEN, 153 2 * ETH_ALEN); 154 } 155 156 skb->dev = ds->ports[source_port].netdev; 157 158 return skb; 159 } 160 161 const struct dsa_device_ops dsa_netdev_ops = { 162 .xmit = dsa_xmit, 163 .rcv = dsa_rcv, 164 }; 165