1// SPDX-License-Identifier: GPL-2.0+
 2/*
 3 * net/dsa/tag_trailer.c - Trailer tag format handling
 4 * Copyright (c) 2008-2009 Marvell Semiconductor
 
 
 
 
 
 5 */
 6
 7#include <linux/etherdevice.h>
 8#include <linux/list.h>
 9#include <linux/slab.h>
10
11#include "tag.h"
12
13#define TRAILER_NAME "trailer"
14
15static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
16{
17	struct dsa_port *dp = dsa_user_to_port(dev);
 
 
18	u8 *trailer;
19
20	trailer = skb_put(skb, 4);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
21	trailer[0] = 0x80;
22	trailer[1] = 1 << dp->index;
23	trailer[2] = 0x10;
24	trailer[3] = 0x00;
25
26	return skb;
27}
28
29static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev)
 
30{
31	u8 *trailer;
32	int source_port;
33
34	if (skb_linearize(skb))
35		return NULL;
36
37	trailer = skb_tail_pointer(skb) - 4;
38	if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
39	    (trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00)
40		return NULL;
41
42	source_port = trailer[1] & 7;
43
44	skb->dev = dsa_conduit_find_user(dev, 0, source_port);
45	if (!skb->dev)
46		return NULL;
47
48	if (pskb_trim_rcsum(skb, skb->len - 4))
49		return NULL;
50
51	return skb;
52}
53
54static const struct dsa_device_ops trailer_netdev_ops = {
55	.name	= TRAILER_NAME,
56	.proto	= DSA_TAG_PROTO_TRAILER,
57	.xmit	= trailer_xmit,
58	.rcv	= trailer_rcv,
59	.needed_tailroom = 4,
60};
61
62MODULE_DESCRIPTION("DSA tag driver for switches using a trailer tag");
63MODULE_LICENSE("GPL");
64MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_TRAILER, TRAILER_NAME);
65
66module_dsa_tag_driver(trailer_netdev_ops);

 
 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
15#include "dsa_priv.h"
 
 
16
17static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
18{
19	struct dsa_port *dp = dsa_slave_to_port(dev);
20	struct sk_buff *nskb;
21	int padlen;
22	u8 *trailer;
23
24	/*
25	 * We have to make sure that the trailer ends up as the very
26	 * last 4 bytes of the packet.  This means that we have to pad
27	 * the packet to the minimum ethernet frame size, if necessary,
28	 * before adding the trailer.
29	 */
30	padlen = 0;
31	if (skb->len < 60)
32		padlen = 60 - skb->len;
33
34	nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
35	if (!nskb)
36		return NULL;
37	skb_reserve(nskb, NET_IP_ALIGN);
38
39	skb_reset_mac_header(nskb);
40	skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
41	skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
42	skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
43	consume_skb(skb);
44
45	if (padlen) {
46		skb_put_zero(nskb, padlen);
47	}
48
49	trailer = skb_put(nskb, 4);
50	trailer[0] = 0x80;
51	trailer[1] = 1 << dp->index;
52	trailer[2] = 0x10;
53	trailer[3] = 0x00;
54
55	return nskb;
56}
57
58static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev,
59				   struct packet_type *pt)
60{
61	u8 *trailer;
62	int source_port;
63
64	if (skb_linearize(skb))
65		return NULL;
66
67	trailer = skb_tail_pointer(skb) - 4;
68	if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
69	    (trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00)
70		return NULL;
71
72	source_port = trailer[1] & 7;
73
74	skb->dev = dsa_master_find_slave(dev, 0, source_port);
75	if (!skb->dev)
76		return NULL;
77
78	pskb_trim_rcsum(skb, skb->len - 4);
 
79
80	return skb;
81}
82
83const struct dsa_device_ops trailer_netdev_ops = {
 
 
84	.xmit	= trailer_xmit,
85	.rcv	= trailer_rcv,
 
86};