/net/dsa/tag_dsa.c

  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/netdevice.h>
 14#include <linux/slab.h>
 15#include "dsa_priv.h"
 16
 17#define DSA_HLEN	4
 18
 19netdev_tx_t dsa_xmit(struct sk_buff *skb, struct net_device *dev)
 20{
 21	struct dsa_slave_priv *p = netdev_priv(dev);
 22	u8 *dsa_header;
 23
 24	dev->stats.tx_packets++;
 25	dev->stats.tx_bytes += skb->len;
 26
 27	/*
 28	 * Convert the outermost 802.1q tag to a DSA tag for tagged
 29	 * packets, or insert a DSA tag between the addresses and
 30	 * the ethertype field for untagged packets.
 31	 */
 32	if (skb->protocol == htons(ETH_P_8021Q)) {
 33		if (skb_cow_head(skb, 0) < 0)
 34			goto out_free;
 35
 36		/*
 37		 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
 38		 */
 39		dsa_header = skb->data + 2 * ETH_ALEN;
 40		dsa_header[0] = 0x60 | p->parent->index;
 41		dsa_header[1] = p->port << 3;
 42
 43		/*
 44		 * Move CFI field from byte 2 to byte 1.
 45		 */
 46		if (dsa_header[2] & 0x10) {
 47			dsa_header[1] |= 0x01;
 48			dsa_header[2] &= ~0x10;
 49		}
 50	} else {
 51		if (skb_cow_head(skb, DSA_HLEN) < 0)
 52			goto out_free;
 53		skb_push(skb, DSA_HLEN);
 54
 55		memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
 56
 57		/*
 58		 * Construct untagged FROM_CPU DSA tag.
 59		 */
 60		dsa_header = skb->data + 2 * ETH_ALEN;
 61		dsa_header[0] = 0x40 | p->parent->index;
 62		dsa_header[1] = p->port << 3;
 63		dsa_header[2] = 0x00;
 64		dsa_header[3] = 0x00;
 65	}
 66
 67	skb->protocol = htons(ETH_P_DSA);
 68
 69	skb->dev = p->parent->dst->master_netdev;
 70	dev_queue_xmit(skb);
 71
 72	return NETDEV_TX_OK;
 73
 74out_free:
 75	kfree_skb(skb);
 76	return NETDEV_TX_OK;
 77}
 78
 79static int dsa_rcv(struct sk_buff *skb, struct net_device *dev,
 80		   struct packet_type *pt, struct net_device *orig_dev)
 81{
 82	struct dsa_switch_tree *dst = dev->dsa_ptr;
 83	struct dsa_switch *ds;
 84	u8 *dsa_header;
 85	int source_device;
 86	int source_port;
 87
 88	if (unlikely(dst == NULL))
 89		goto out_drop;
 90
 91	skb = skb_unshare(skb, GFP_ATOMIC);
 92	if (skb == NULL)
 93		goto out;
 94
 95	if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
 96		goto out_drop;
 97
 98	/*
 99	 * The ethertype field is part of the DSA header.
100	 */
101	dsa_header = skb->data - 2;
102
103	/*
104	 * Check that frame type is either TO_CPU or FORWARD.
105	 */
106	if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
107		goto out_drop;
108
109	/*
110	 * Determine source device and port.
111	 */
112	source_device = dsa_header[0] & 0x1f;
113	source_port = (dsa_header[1] >> 3) & 0x1f;
114
115	/*
116	 * Check that the source device exists and that the source
117	 * port is a registered DSA port.
118	 */
119	if (source_device >= dst->pd->nr_chips)
120		goto out_drop;
121	ds = dst->ds[source_device];
122	if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
123		goto out_drop;
124
125	/*
126	 * Convert the DSA header to an 802.1q header if the 'tagged'
127	 * bit in the DSA header is set.  If the 'tagged' bit is clear,
128	 * delete the DSA header entirely.
129	 */
130	if (dsa_header[0] & 0x20) {
131		u8 new_header[4];
132
133		/*
134		 * Insert 802.1q ethertype and copy the VLAN-related
135		 * fields, but clear the bit that will hold CFI (since
136		 * DSA uses that bit location for another purpose).
137		 */
138		new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
139		new_header[1] = ETH_P_8021Q & 0xff;
140		new_header[2] = dsa_header[2] & ~0x10;
141		new_header[3] = dsa_header[3];
142
143		/*
144		 * Move CFI bit from its place in the DSA header to
145		 * its 802.1q-designated place.
146		 */
147		if (dsa_header[1] & 0x01)
148			new_header[2] |= 0x10;
149
150		/*
151		 * Update packet checksum if skb is CHECKSUM_COMPLETE.
152		 */
153		if (skb->ip_summed == CHECKSUM_COMPLETE) {
154			__wsum c = skb->csum;
155			c = csum_add(c, csum_partial(new_header + 2, 2, 0));
156			c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
157			skb->csum = c;
158		}
159
160		memcpy(dsa_header, new_header, DSA_HLEN);
161	} else {
162		/*
163		 * Remove DSA tag and update checksum.
164		 */
165		skb_pull_rcsum(skb, DSA_HLEN);
166		memmove(skb->data - ETH_HLEN,
167			skb->data - ETH_HLEN - DSA_HLEN,
168			2 * ETH_ALEN);
169	}
170
171	skb->dev = ds->ports[source_port];
172	skb_push(skb, ETH_HLEN);
173	skb->pkt_type = PACKET_HOST;
174	skb->protocol = eth_type_trans(skb, skb->dev);
175
176	skb->dev->stats.rx_packets++;
177	skb->dev->stats.rx_bytes += skb->len;
178
179	netif_receive_skb(skb);
180
181	return 0;
182
183out_drop:
184	kfree_skb(skb);
185out:
186	return 0;
187}
188
189static struct packet_type dsa_packet_type __read_mostly = {
190	.type	= cpu_to_be16(ETH_P_DSA),
191	.func	= dsa_rcv,
192};
193
194static int __init dsa_init_module(void)
195{
196	dev_add_pack(&dsa_packet_type);
197	return 0;
198}
199module_init(dsa_init_module);
200
201static void __exit dsa_cleanup_module(void)
202{
203	dev_remove_pack(&dsa_packet_type);
204}
205module_exit(dsa_cleanup_module);