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Linux/net/dsa/tag_dsa.c

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  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 netdev_tx_t 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         dev->stats.tx_packets++;
 24         dev->stats.tx_bytes += skb->len;
 25 
 26         /*
 27          * Convert the outermost 802.1q tag to a DSA tag for tagged
 28          * packets, or insert a DSA tag between the addresses and
 29          * the ethertype field for untagged packets.
 30          */
 31         if (skb->protocol == htons(ETH_P_8021Q)) {
 32                 if (skb_cow_head(skb, 0) < 0)
 33                         goto out_free;
 34 
 35                 /*
 36                  * Construct tagged FROM_CPU DSA tag from 802.1q tag.
 37                  */
 38                 dsa_header = skb->data + 2 * ETH_ALEN;
 39                 dsa_header[0] = 0x60 | p->parent->index;
 40                 dsa_header[1] = p->port << 3;
 41 
 42                 /*
 43                  * Move CFI field from byte 2 to byte 1.
 44                  */
 45                 if (dsa_header[2] & 0x10) {
 46                         dsa_header[1] |= 0x01;
 47                         dsa_header[2] &= ~0x10;
 48                 }
 49         } else {
 50                 if (skb_cow_head(skb, DSA_HLEN) < 0)
 51                         goto out_free;
 52                 skb_push(skb, DSA_HLEN);
 53 
 54                 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
 55 
 56                 /*
 57                  * Construct untagged FROM_CPU DSA tag.
 58                  */
 59                 dsa_header = skb->data + 2 * ETH_ALEN;
 60                 dsa_header[0] = 0x40 | p->parent->index;
 61                 dsa_header[1] = p->port << 3;
 62                 dsa_header[2] = 0x00;
 63                 dsa_header[3] = 0x00;
 64         }
 65 
 66         skb->dev = p->parent->dst->master_netdev;
 67         dev_queue_xmit(skb);
 68 
 69         return NETDEV_TX_OK;
 70 
 71 out_free:
 72         kfree_skb(skb);
 73         return NETDEV_TX_OK;
 74 }
 75 
 76 static int dsa_rcv(struct sk_buff *skb, struct net_device *dev,
 77                    struct packet_type *pt, struct net_device *orig_dev)
 78 {
 79         struct dsa_switch_tree *dst = dev->dsa_ptr;
 80         struct dsa_switch *ds;
 81         u8 *dsa_header;
 82         int source_device;
 83         int source_port;
 84 
 85         if (unlikely(dst == NULL))
 86                 goto out_drop;
 87 
 88         skb = skb_unshare(skb, GFP_ATOMIC);
 89         if (skb == NULL)
 90                 goto out;
 91 
 92         if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
 93                 goto out_drop;
 94 
 95         /*
 96          * The ethertype field is part of the DSA header.
 97          */
 98         dsa_header = skb->data - 2;
 99 
100         /*
101          * Check that frame type is either TO_CPU or FORWARD.
102          */
103         if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
104                 goto out_drop;
105 
106         /*
107          * Determine source device and port.
108          */
109         source_device = dsa_header[0] & 0x1f;
110         source_port = (dsa_header[1] >> 3) & 0x1f;
111 
112         /*
113          * Check that the source device exists and that the source
114          * port is a registered DSA port.
115          */
116         if (source_device >= dst->pd->nr_chips)
117                 goto out_drop;
118         ds = dst->ds[source_device];
119         if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
120                 goto out_drop;
121 
122         /*
123          * Convert the DSA header to an 802.1q header if the 'tagged'
124          * bit in the DSA header is set.  If the 'tagged' bit is clear,
125          * delete the DSA header entirely.
126          */
127         if (dsa_header[0] & 0x20) {
128                 u8 new_header[4];
129 
130                 /*
131                  * Insert 802.1q ethertype and copy the VLAN-related
132                  * fields, but clear the bit that will hold CFI (since
133                  * DSA uses that bit location for another purpose).
134                  */
135                 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
136                 new_header[1] = ETH_P_8021Q & 0xff;
137                 new_header[2] = dsa_header[2] & ~0x10;
138                 new_header[3] = dsa_header[3];
139 
140                 /*
141                  * Move CFI bit from its place in the DSA header to
142                  * its 802.1q-designated place.
143                  */
144                 if (dsa_header[1] & 0x01)
145                         new_header[2] |= 0x10;
146 
147                 /*
148                  * Update packet checksum if skb is CHECKSUM_COMPLETE.
149                  */
150                 if (skb->ip_summed == CHECKSUM_COMPLETE) {
151                         __wsum c = skb->csum;
152                         c = csum_add(c, csum_partial(new_header + 2, 2, 0));
153                         c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
154                         skb->csum = c;
155                 }
156 
157                 memcpy(dsa_header, new_header, DSA_HLEN);
158         } else {
159                 /*
160                  * Remove DSA tag and update checksum.
161                  */
162                 skb_pull_rcsum(skb, DSA_HLEN);
163                 memmove(skb->data - ETH_HLEN,
164                         skb->data - ETH_HLEN - DSA_HLEN,
165                         2 * ETH_ALEN);
166         }
167 
168         skb->dev = ds->ports[source_port];
169         skb_push(skb, ETH_HLEN);
170         skb->pkt_type = PACKET_HOST;
171         skb->protocol = eth_type_trans(skb, skb->dev);
172 
173         skb->dev->stats.rx_packets++;
174         skb->dev->stats.rx_bytes += skb->len;
175 
176         netif_receive_skb(skb);
177 
178         return 0;
179 
180 out_drop:
181         kfree_skb(skb);
182 out:
183         return 0;
184 }
185 
186 const struct dsa_device_ops dsa_netdev_ops = {
187         .xmit   = dsa_xmit,
188         .rcv    = dsa_rcv,
189 };
190 

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