Linux 4.8-rc8
[linux/fpc-iii.git] / net / dsa / tag_trailer.c
blob5e3903eb1afa644b8b8861e60e112957346e5104
1 /*
2 * net/dsa/tag_trailer.c - Trailer tag format handling
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.
9 */
11 #include <linux/etherdevice.h>
12 #include <linux/list.h>
13 #include <linux/slab.h>
14 #include "dsa_priv.h"
16 static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
18 struct dsa_slave_priv *p = netdev_priv(dev);
19 struct sk_buff *nskb;
20 int padlen;
21 u8 *trailer;
24 * We have to make sure that the trailer ends up as the very
25 * last 4 bytes of the packet. This means that we have to pad
26 * the packet to the minimum ethernet frame size, if necessary,
27 * before adding the trailer.
29 padlen = 0;
30 if (skb->len < 60)
31 padlen = 60 - skb->len;
33 nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
34 if (nskb == NULL) {
35 kfree_skb(skb);
36 return NULL;
38 skb_reserve(nskb, NET_IP_ALIGN);
40 skb_reset_mac_header(nskb);
41 skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
42 skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
43 skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
44 kfree_skb(skb);
46 if (padlen) {
47 u8 *pad = skb_put(nskb, padlen);
48 memset(pad, 0, padlen);
51 trailer = skb_put(nskb, 4);
52 trailer[0] = 0x80;
53 trailer[1] = 1 << p->port;
54 trailer[2] = 0x10;
55 trailer[3] = 0x00;
57 return nskb;
60 static int trailer_rcv(struct sk_buff *skb, struct net_device *dev,
61 struct packet_type *pt, struct net_device *orig_dev)
63 struct dsa_switch_tree *dst = dev->dsa_ptr;
64 struct dsa_switch *ds;
65 u8 *trailer;
66 int source_port;
68 if (unlikely(dst == NULL))
69 goto out_drop;
70 ds = dst->ds[0];
72 skb = skb_unshare(skb, GFP_ATOMIC);
73 if (skb == NULL)
74 goto out;
76 if (skb_linearize(skb))
77 goto out_drop;
79 trailer = skb_tail_pointer(skb) - 4;
80 if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
81 (trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00)
82 goto out_drop;
84 source_port = trailer[1] & 7;
85 if (source_port >= DSA_MAX_PORTS || !ds->ports[source_port].netdev)
86 goto out_drop;
88 pskb_trim_rcsum(skb, skb->len - 4);
90 skb->dev = ds->ports[source_port].netdev;
91 skb_push(skb, ETH_HLEN);
92 skb->pkt_type = PACKET_HOST;
93 skb->protocol = eth_type_trans(skb, skb->dev);
95 skb->dev->stats.rx_packets++;
96 skb->dev->stats.rx_bytes += skb->len;
98 netif_receive_skb(skb);
100 return 0;
102 out_drop:
103 kfree_skb(skb);
104 out:
105 return 0;
108 const struct dsa_device_ops trailer_netdev_ops = {
109 .xmit = trailer_xmit,
110 .rcv = trailer_rcv,