1/*
2 * net/dsa/tag_trailer.c - Trailer tag format handling
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
16static netdev_tx_t trailer_xmit(struct sk_buff *skb, struct net_device *dev)
17{
18	struct dsa_slave_priv *p = netdev_priv(dev);
19	struct sk_buff *nskb;
20	int padlen;
21	u8 *trailer;
22
23	dev->stats.tx_packets++;
24	dev->stats.tx_bytes += skb->len;
25
26	/*
27	 * We have to make sure that the trailer ends up as the very
28	 * last 4 bytes of the packet.  This means that we have to pad
29	 * the packet to the minimum ethernet frame size, if necessary,
30	 * before adding the trailer.
31	 */
32	padlen = 0;
33	if (skb->len < 60)
34		padlen = 60 - skb->len;
35
36	nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
37	if (nskb == NULL) {
38		kfree_skb(skb);
39		return NETDEV_TX_OK;
40	}
41	skb_reserve(nskb, NET_IP_ALIGN);
42
43	skb_reset_mac_header(nskb);
44	skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
45	skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
46	skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
47	kfree_skb(skb);
48
49	if (padlen) {
50		u8 *pad = skb_put(nskb, padlen);
51		memset(pad, 0, padlen);
52	}
53
54	trailer = skb_put(nskb, 4);
55	trailer[0] = 0x80;
56	trailer[1] = 1 << p->port;
57	trailer[2] = 0x10;
58	trailer[3] = 0x00;
59
60	nskb->protocol = htons(ETH_P_TRAILER);
61
62	nskb->dev = p->parent->dst->master_netdev;
63	dev_queue_xmit(nskb);
64
65	return NETDEV_TX_OK;
66}
67
68static int trailer_rcv(struct sk_buff *skb, struct net_device *dev,
69		       struct packet_type *pt, struct net_device *orig_dev)
70{
71	struct dsa_switch_tree *dst = dev->dsa_ptr;
72	struct dsa_switch *ds;
73	u8 *trailer;
74	int source_port;
75
76	if (unlikely(dst == NULL))
77		goto out_drop;
78	ds = dst->ds[0];
79
80	skb = skb_unshare(skb, GFP_ATOMIC);
81	if (skb == NULL)
82		goto out;
83
84	if (skb_linearize(skb))
85		goto out_drop;
86
87	trailer = skb_tail_pointer(skb) - 4;
88	if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
89	    (trailer[3] & 0xef) != 0x00 || trailer[3] != 0x00)
90		goto out_drop;
91
92	source_port = trailer[1] & 7;
93	if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
94		goto out_drop;
95
96	pskb_trim_rcsum(skb, skb->len - 4);
97
98	skb->dev = ds->ports[source_port];
99	skb_push(skb, ETH_HLEN);
100	skb->pkt_type = PACKET_HOST;
101	skb->protocol = eth_type_trans(skb, skb->dev);
102
103	skb->dev->stats.rx_packets++;
104	skb->dev->stats.rx_bytes += skb->len;
105
106	netif_receive_skb(skb);
107
108	return 0;
109
110out_drop:
111	kfree_skb(skb);
112out:
113	return 0;
114}
115
116const struct dsa_device_ops trailer_netdev_ops = {
117	.xmit	= trailer_xmit,
118	.rcv	= trailer_rcv,
119};
120