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_port *dp = dsa_slave_to_port(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 | dp->ds->index; 38 dsa_header[1] = 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 | dp->ds->index; 59 dsa_header[1] = 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 u8 *dsa_header; 71 int source_device; 72 int source_port; 73 74 if (unlikely(!pskb_may_pull(skb, DSA_HLEN))) 75 return NULL; 76 77 /* 78 * The ethertype field is part of the DSA header. 79 */ 80 dsa_header = skb->data - 2; 81 82 /* 83 * Check that frame type is either TO_CPU or FORWARD. 84 */ 85 if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0) 86 return NULL; 87 88 /* 89 * Determine source device and port. 90 */ 91 source_device = dsa_header[0] & 0x1f; 92 source_port = (dsa_header[1] >> 3) & 0x1f; 93 94 skb->dev = dsa_master_find_slave(dev, source_device, source_port); 95 if (!skb->dev) 96 return NULL; 97 98 /* 99 * Convert the DSA header to an 802.1q header if the 'tagged' 100 * bit in the DSA header is set. If the 'tagged' bit is clear, 101 * delete the DSA header entirely. 102 */ 103 if (dsa_header[0] & 0x20) { 104 u8 new_header[4]; 105 106 /* 107 * Insert 802.1q ethertype and copy the VLAN-related 108 * fields, but clear the bit that will hold CFI (since 109 * DSA uses that bit location for another purpose). 110 */ 111 new_header[0] = (ETH_P_8021Q >> 8) & 0xff; 112 new_header[1] = ETH_P_8021Q & 0xff; 113 new_header[2] = dsa_header[2] & ~0x10; 114 new_header[3] = dsa_header[3]; 115 116 /* 117 * Move CFI bit from its place in the DSA header to 118 * its 802.1q-designated place. 119 */ 120 if (dsa_header[1] & 0x01) 121 new_header[2] |= 0x10; 122 123 /* 124 * Update packet checksum if skb is CHECKSUM_COMPLETE. 125 */ 126 if (skb->ip_summed == CHECKSUM_COMPLETE) { 127 __wsum c = skb->csum; 128 c = csum_add(c, csum_partial(new_header + 2, 2, 0)); 129 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0)); 130 skb->csum = c; 131 } 132 133 memcpy(dsa_header, new_header, DSA_HLEN); 134 } else { 135 /* 136 * Remove DSA tag and update checksum. 137 */ 138 skb_pull_rcsum(skb, DSA_HLEN); 139 memmove(skb->data - ETH_HLEN, 140 skb->data - ETH_HLEN - DSA_HLEN, 141 2 * ETH_ALEN); 142 } 143 144 skb->offload_fwd_mark = 1; 145 146 return skb; 147 } 148 149 const struct dsa_device_ops dsa_netdev_ops = { 150 .xmit = dsa_xmit, 151 .rcv = dsa_rcv, 152 }; 153