2 * net/dsa/tag_dsa.c - (Non-ethertype) DSA tagging
3 * Copyright (c) 2008-2009 Marvell Semiconductor
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.
11 #include <linux/etherdevice.h>
12 #include <linux/list.h>
13 #include <linux/slab.h>
19 static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
21 struct dsa_slave_priv *p = netdev_priv(dev);
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.
29 if (skb->protocol == htons(ETH_P_8021Q)) {
30 if (skb_cow_head(skb, 0) < 0)
34 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
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;
41 * Move CFI field from byte 2 to byte 1.
43 if (dsa_header[2] & 0x10) {
44 dsa_header[1] |= 0x01;
45 dsa_header[2] &= ~0x10;
48 if (skb_cow_head(skb, DSA_HLEN) < 0)
50 skb_push(skb, DSA_HLEN);
52 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
55 * Construct untagged FROM_CPU DSA tag.
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;
71 static int dsa_rcv(struct sk_buff *skb, struct net_device *dev,
72 struct packet_type *pt, struct net_device *orig_dev)
74 struct dsa_switch_tree *dst = dev->dsa_ptr;
75 struct dsa_switch *ds;
80 skb = skb_unshare(skb, GFP_ATOMIC);
84 if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
88 * The ethertype field is part of the DSA header.
90 dsa_header = skb->data - 2;
93 * Check that frame type is either TO_CPU or FORWARD.
95 if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
99 * Determine source device and port.
101 source_device = dsa_header[0] & 0x1f;
102 source_port = (dsa_header[1] >> 3) & 0x1f;
105 * Check that the source device exists and that the source
106 * port is a registered DSA port.
108 if (source_device >= DSA_MAX_SWITCHES)
111 ds = dst->ds[source_device];
115 if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
119 * Convert the DSA header to an 802.1q header if the 'tagged'
120 * bit in the DSA header is set. If the 'tagged' bit is clear,
121 * delete the DSA header entirely.
123 if (dsa_header[0] & 0x20) {
127 * Insert 802.1q ethertype and copy the VLAN-related
128 * fields, but clear the bit that will hold CFI (since
129 * DSA uses that bit location for another purpose).
131 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
132 new_header[1] = ETH_P_8021Q & 0xff;
133 new_header[2] = dsa_header[2] & ~0x10;
134 new_header[3] = dsa_header[3];
137 * Move CFI bit from its place in the DSA header to
138 * its 802.1q-designated place.
140 if (dsa_header[1] & 0x01)
141 new_header[2] |= 0x10;
144 * Update packet checksum if skb is CHECKSUM_COMPLETE.
146 if (skb->ip_summed == CHECKSUM_COMPLETE) {
147 __wsum c = skb->csum;
148 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
149 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
153 memcpy(dsa_header, new_header, DSA_HLEN);
156 * Remove DSA tag and update checksum.
158 skb_pull_rcsum(skb, DSA_HLEN);
159 memmove(skb->data - ETH_HLEN,
160 skb->data - ETH_HLEN - DSA_HLEN,
164 skb->dev = ds->ports[source_port].netdev;
165 skb_push(skb, ETH_HLEN);
166 skb->pkt_type = PACKET_HOST;
167 skb->protocol = eth_type_trans(skb, skb->dev);
169 skb->dev->stats.rx_packets++;
170 skb->dev->stats.rx_bytes += skb->len;
172 netif_receive_skb(skb);
182 const struct dsa_device_ops dsa_netdev_ops = {