1/*
  2 * net/dsa/tag_edsa.c - 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#define EDSA_HLEN	8
 19
 20netdev_tx_t edsa_xmit(struct sk_buff *skb, struct net_device *dev)
 21{
 22	struct dsa_slave_priv *p = netdev_priv(dev);
 23	u8 *edsa_header;
 24
 25	dev->stats.tx_packets++;
 26	dev->stats.tx_bytes += skb->len;
 27
 28	/*
 29	 * Convert the outermost 802.1q tag to a DSA tag and prepend
 30	 * a DSA ethertype field is the packet is tagged, or insert
 31	 * a DSA ethertype plus DSA tag between the addresses and the
 32	 * current ethertype field if the packet is untagged.
 33	 */
 34	if (skb->protocol == htons(ETH_P_8021Q)) {
 35		if (skb_cow_head(skb, DSA_HLEN) < 0)
 36			goto out_free;
 37		skb_push(skb, DSA_HLEN);
 38
 39		memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
 40
 41		/*
 42		 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
 43		 */
 44		edsa_header = skb->data + 2 * ETH_ALEN;
 45		edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
 46		edsa_header[1] = ETH_P_EDSA & 0xff;
 47		edsa_header[2] = 0x00;
 48		edsa_header[3] = 0x00;
 49		edsa_header[4] = 0x60 | p->parent->index;
 50		edsa_header[5] = p->port << 3;
 51
 52		/*
 53		 * Move CFI field from byte 6 to byte 5.
 54		 */
 55		if (edsa_header[6] & 0x10) {
 56			edsa_header[5] |= 0x01;
 57			edsa_header[6] &= ~0x10;
 58		}
 59	} else {
 60		if (skb_cow_head(skb, EDSA_HLEN) < 0)
 61			goto out_free;
 62		skb_push(skb, EDSA_HLEN);
 63
 64		memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
 65
 66		/*
 67		 * Construct untagged FROM_CPU DSA tag.
 68		 */
 69		edsa_header = skb->data + 2 * ETH_ALEN;
 70		edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
 71		edsa_header[1] = ETH_P_EDSA & 0xff;
 72		edsa_header[2] = 0x00;
 73		edsa_header[3] = 0x00;
 74		edsa_header[4] = 0x40 | p->parent->index;
 75		edsa_header[5] = p->port << 3;
 76		edsa_header[6] = 0x00;
 77		edsa_header[7] = 0x00;
 78	}
 79
 80	skb->protocol = htons(ETH_P_EDSA);
 81
 82	skb->dev = p->parent->dst->master_netdev;
 83	dev_queue_xmit(skb);
 84
 85	return NETDEV_TX_OK;
 86
 87out_free:
 88	kfree_skb(skb);
 89	return NETDEV_TX_OK;
 90}
 91
 92static int edsa_rcv(struct sk_buff *skb, struct net_device *dev,
 93		    struct packet_type *pt, struct net_device *orig_dev)
 94{
 95	struct dsa_switch_tree *dst = dev->dsa_ptr;
 96	struct dsa_switch *ds;
 97	u8 *edsa_header;
 98	int source_device;
 99	int source_port;
100
101	if (unlikely(dst == NULL))
102		goto out_drop;
103
104	skb = skb_unshare(skb, GFP_ATOMIC);
105	if (skb == NULL)
106		goto out;
107
108	if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
109		goto out_drop;
110
111	/*
112	 * Skip the two null bytes after the ethertype.
113	 */
114	edsa_header = skb->data + 2;
115
116	/*
117	 * Check that frame type is either TO_CPU or FORWARD.
118	 */
119	if ((edsa_header[0] & 0xc0) != 0x00 && (edsa_header[0] & 0xc0) != 0xc0)
120		goto out_drop;
121
122	/*
123	 * Determine source device and port.
124	 */
125	source_device = edsa_header[0] & 0x1f;
126	source_port = (edsa_header[1] >> 3) & 0x1f;
127
128	/*
129	 * Check that the source device exists and that the source
130	 * port is a registered DSA port.
131	 */
132	if (source_device >= dst->pd->nr_chips)
133		goto out_drop;
134	ds = dst->ds[source_device];
135	if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
136		goto out_drop;
137
138	/*
139	 * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
140	 * tag and delete the ethertype part.  If the 'tagged' bit is
141	 * clear, delete the ethertype and the DSA tag parts.
142	 */
143	if (edsa_header[0] & 0x20) {
144		u8 new_header[4];
145
146		/*
147		 * Insert 802.1q ethertype and copy the VLAN-related
148		 * fields, but clear the bit that will hold CFI (since
149		 * DSA uses that bit location for another purpose).
150		 */
151		new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
152		new_header[1] = ETH_P_8021Q & 0xff;
153		new_header[2] = edsa_header[2] & ~0x10;
154		new_header[3] = edsa_header[3];
155
156		/*
157		 * Move CFI bit from its place in the DSA header to
158		 * its 802.1q-designated place.
159		 */
160		if (edsa_header[1] & 0x01)
161			new_header[2] |= 0x10;
162
163		skb_pull_rcsum(skb, DSA_HLEN);
164
165		/*
166		 * Update packet checksum if skb is CHECKSUM_COMPLETE.
167		 */
168		if (skb->ip_summed == CHECKSUM_COMPLETE) {
169			__wsum c = skb->csum;
170			c = csum_add(c, csum_partial(new_header + 2, 2, 0));
171			c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
172			skb->csum = c;
173		}
174
175		memcpy(edsa_header, new_header, DSA_HLEN);
176
177		memmove(skb->data - ETH_HLEN,
178			skb->data - ETH_HLEN - DSA_HLEN,
179			2 * ETH_ALEN);
180	} else {
181		/*
182		 * Remove DSA tag and update checksum.
183		 */
184		skb_pull_rcsum(skb, EDSA_HLEN);
185		memmove(skb->data - ETH_HLEN,
186			skb->data - ETH_HLEN - EDSA_HLEN,
187			2 * ETH_ALEN);
188	}
189
190	skb->dev = ds->ports[source_port];
191	skb_push(skb, ETH_HLEN);
192	skb->pkt_type = PACKET_HOST;
193	skb->protocol = eth_type_trans(skb, skb->dev);
194
195	skb->dev->stats.rx_packets++;
196	skb->dev->stats.rx_bytes += skb->len;
197
198	netif_receive_skb(skb);
199
200	return 0;
201
202out_drop:
203	kfree_skb(skb);
204out:
205	return 0;
206}
207
208static struct packet_type edsa_packet_type __read_mostly = {
209	.type	= cpu_to_be16(ETH_P_EDSA),
210	.func	= edsa_rcv,
211};
212
213static int __init edsa_init_module(void)
214{
215	dev_add_pack(&edsa_packet_type);
216	return 0;
217}
218module_init(edsa_init_module);
219
220static void __exit edsa_cleanup_module(void)
221{
222	dev_remove_pack(&edsa_packet_type);
223}
224module_exit(edsa_cleanup_module);