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tag_edsa.c
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1 /*
2  * net/dsa/tag_edsa.c - 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/netdevice.h>
14 #include <linux/slab.h>
15 #include "dsa_priv.h"
16 
17 #define DSA_HLEN 4
18 #define EDSA_HLEN 8
19 
21 {
22  struct dsa_slave_priv *p = netdev_priv(dev);
23  u8 *edsa_header;
24 
25  dev->stats.tx_packets++;
26  dev->stats.tx_bytes += skb->len;
27 
28  /*
29  * Convert the outermost 802.1q tag to a DSA tag and prepend
30  * a DSA ethertype field is the packet is tagged, or insert
31  * a DSA ethertype plus DSA tag between the addresses and the
32  * current ethertype field if the packet is untagged.
33  */
34  if (skb->protocol == htons(ETH_P_8021Q)) {
35  if (skb_cow_head(skb, DSA_HLEN) < 0)
36  goto out_free;
37  skb_push(skb, DSA_HLEN);
38 
39  memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
40 
41  /*
42  * Construct tagged FROM_CPU DSA tag from 802.1q tag.
43  */
44  edsa_header = skb->data + 2 * ETH_ALEN;
45  edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
46  edsa_header[1] = ETH_P_EDSA & 0xff;
47  edsa_header[2] = 0x00;
48  edsa_header[3] = 0x00;
49  edsa_header[4] = 0x60 | p->parent->index;
50  edsa_header[5] = p->port << 3;
51 
52  /*
53  * Move CFI field from byte 6 to byte 5.
54  */
55  if (edsa_header[6] & 0x10) {
56  edsa_header[5] |= 0x01;
57  edsa_header[6] &= ~0x10;
58  }
59  } else {
60  if (skb_cow_head(skb, EDSA_HLEN) < 0)
61  goto out_free;
62  skb_push(skb, EDSA_HLEN);
63 
64  memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
65 
66  /*
67  * Construct untagged FROM_CPU DSA tag.
68  */
69  edsa_header = skb->data + 2 * ETH_ALEN;
70  edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
71  edsa_header[1] = ETH_P_EDSA & 0xff;
72  edsa_header[2] = 0x00;
73  edsa_header[3] = 0x00;
74  edsa_header[4] = 0x40 | p->parent->index;
75  edsa_header[5] = p->port << 3;
76  edsa_header[6] = 0x00;
77  edsa_header[7] = 0x00;
78  }
79 
80  skb->protocol = htons(ETH_P_EDSA);
81 
82  skb->dev = p->parent->dst->master_netdev;
83  dev_queue_xmit(skb);
84 
85  return NETDEV_TX_OK;
86 
87 out_free:
88  kfree_skb(skb);
89  return NETDEV_TX_OK;
90 }
91 
92 static int edsa_rcv(struct sk_buff *skb, struct net_device *dev,
93  struct packet_type *pt, struct net_device *orig_dev)
94 {
95  struct dsa_switch_tree *dst = dev->dsa_ptr;
96  struct dsa_switch *ds;
97  u8 *edsa_header;
98  int source_device;
99  int source_port;
100 
101  if (unlikely(dst == NULL))
102  goto out_drop;
103 
104  skb = skb_unshare(skb, GFP_ATOMIC);
105  if (skb == NULL)
106  goto out;
107 
108  if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
109  goto out_drop;
110 
111  /*
112  * Skip the two null bytes after the ethertype.
113  */
114  edsa_header = skb->data + 2;
115 
116  /*
117  * Check that frame type is either TO_CPU or FORWARD.
118  */
119  if ((edsa_header[0] & 0xc0) != 0x00 && (edsa_header[0] & 0xc0) != 0xc0)
120  goto out_drop;
121 
122  /*
123  * Determine source device and port.
124  */
125  source_device = edsa_header[0] & 0x1f;
126  source_port = (edsa_header[1] >> 3) & 0x1f;
127 
128  /*
129  * Check that the source device exists and that the source
130  * port is a registered DSA port.
131  */
132  if (source_device >= dst->pd->nr_chips)
133  goto out_drop;
134  ds = dst->ds[source_device];
135  if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
136  goto out_drop;
137 
138  /*
139  * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
140  * tag and delete the ethertype part. If the 'tagged' bit is
141  * clear, delete the ethertype and the DSA tag parts.
142  */
143  if (edsa_header[0] & 0x20) {
144  u8 new_header[4];
145 
146  /*
147  * Insert 802.1q ethertype and copy the VLAN-related
148  * fields, but clear the bit that will hold CFI (since
149  * DSA uses that bit location for another purpose).
150  */
151  new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
152  new_header[1] = ETH_P_8021Q & 0xff;
153  new_header[2] = edsa_header[2] & ~0x10;
154  new_header[3] = edsa_header[3];
155 
156  /*
157  * Move CFI bit from its place in the DSA header to
158  * its 802.1q-designated place.
159  */
160  if (edsa_header[1] & 0x01)
161  new_header[2] |= 0x10;
162 
163  skb_pull_rcsum(skb, DSA_HLEN);
164 
165  /*
166  * Update packet checksum if skb is CHECKSUM_COMPLETE.
167  */
168  if (skb->ip_summed == CHECKSUM_COMPLETE) {
169  __wsum c = skb->csum;
170  c = csum_add(c, csum_partial(new_header + 2, 2, 0));
171  c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
172  skb->csum = c;
173  }
174 
175  memcpy(edsa_header, new_header, DSA_HLEN);
176 
177  memmove(skb->data - ETH_HLEN,
178  skb->data - ETH_HLEN - DSA_HLEN,
179  2 * ETH_ALEN);
180  } else {
181  /*
182  * Remove DSA tag and update checksum.
183  */
185  memmove(skb->data - ETH_HLEN,
186  skb->data - ETH_HLEN - EDSA_HLEN,
187  2 * ETH_ALEN);
188  }
189 
190  skb->dev = ds->ports[source_port];
191  skb_push(skb, ETH_HLEN);
192  skb->pkt_type = PACKET_HOST;
193  skb->protocol = eth_type_trans(skb, skb->dev);
194 
195  skb->dev->stats.rx_packets++;
196  skb->dev->stats.rx_bytes += skb->len;
197 
198  netif_receive_skb(skb);
199 
200  return 0;
201 
202 out_drop:
203  kfree_skb(skb);
204 out:
205  return 0;
206 }
207 
209  .type = cpu_to_be16(ETH_P_EDSA),
210  .func = edsa_rcv,
211 };