1/*
2 * Linux ARCnet driver - "raw mode" packet encapsulation (no soft headers)
3 *
4 * Written 1994-1999 by Avery Pennarun.
5 * Derived from skeleton.c by Donald Becker.
6 *
7 * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
8 *  for sponsoring the further development of this driver.
9 *
10 * **********************
11 *
12 * The original copyright of skeleton.c was as follows:
13 *
14 * skeleton.c Written 1993 by Donald Becker.
15 * Copyright 1993 United States Government as represented by the
16 * Director, National Security Agency.  This software may only be used
17 * and distributed according to the terms of the GNU General Public License as
18 * modified by SRC, incorporated herein by reference.
19 *
20 * **********************
21 *
22 * For more details, see drivers/net/arcnet.c
23 *
24 * **********************
25 */
26
27#include <linux/module.h>
28#include <linux/init.h>
29#include <linux/if_arp.h>
30#include <net/arp.h>
31#include <linux/netdevice.h>
32#include <linux/skbuff.h>
33#include <linux/arcdevice.h>
34
35#define VERSION "arcnet: raw mode (`r') encapsulation support loaded.\n"
36
37
38static void rx(struct net_device *dev, int bufnum,
39	       struct archdr *pkthdr, int length);
40static int build_header(struct sk_buff *skb, struct net_device *dev,
41			unsigned short type, uint8_t daddr);
42static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
43		      int bufnum);
44
45static struct ArcProto rawmode_proto =
46{
47	.suffix		= 'r',
48	.mtu		= XMTU,
49	.rx		= rx,
50	.build_header	= build_header,
51	.prepare_tx	= prepare_tx,
52	.continue_tx    = NULL,
53	.ack_tx         = NULL
54};
55
56
57static int __init arcnet_raw_init(void)
58{
59	int count;
60
61	printk(VERSION);
62
63	for (count = 0; count < 256; count++)
64		if (arc_proto_map[count] == arc_proto_default)
65			arc_proto_map[count] = &rawmode_proto;
66
67	/* for raw mode, we only set the bcast proto if there's no better one */
68	if (arc_bcast_proto == arc_proto_default)
69		arc_bcast_proto = &rawmode_proto;
70
71	arc_proto_default = &rawmode_proto;
72	return 0;
73}
74
75static void __exit arcnet_raw_exit(void)
76{
77	arcnet_unregister_proto(&rawmode_proto);
78}
79
80module_init(arcnet_raw_init);
81module_exit(arcnet_raw_exit);
82
83MODULE_LICENSE("GPL");
84
85
86/* packet receiver */
87static void rx(struct net_device *dev, int bufnum,
88	       struct archdr *pkthdr, int length)
89{
90	struct arcnet_local *lp = dev->priv;
91	struct sk_buff *skb;
92	struct archdr *pkt = pkthdr;
93	int ofs;
94
95	BUGMSG(D_DURING, "it's a raw packet (length=%d)\n", length);
96
97	if (length > MTU)
98		ofs = 512 - length;
99	else
100		ofs = 256 - length;
101
102	skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
103	if (skb == NULL) {
104		BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");
105		lp->stats.rx_dropped++;
106		return;
107	}
108	skb_put(skb, length + ARC_HDR_SIZE);
109	skb->dev = dev;
110
111	pkt = (struct archdr *) skb->data;
112
113	skb_reset_mac_header(skb);
114	skb_pull(skb, ARC_HDR_SIZE);
115
116	/* up to sizeof(pkt->soft) has already been copied from the card */
117	memcpy(pkt, pkthdr, sizeof(struct archdr));
118	if (length > sizeof(pkt->soft))
119		lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
120				      pkt->soft.raw + sizeof(pkt->soft),
121				      length - sizeof(pkt->soft));
122
123	BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "rx");
124
125	skb->protocol = __constant_htons(ETH_P_ARCNET);
126;
127	netif_rx(skb);
128	dev->last_rx = jiffies;
129}
130
131
132/*
133 * Create the ARCnet hard/soft headers for raw mode.
134 * There aren't any soft headers in raw mode - not even the protocol id.
135 */
136static int build_header(struct sk_buff *skb, struct net_device *dev,
137			unsigned short type, uint8_t daddr)
138{
139	int hdr_size = ARC_HDR_SIZE;
140	struct archdr *pkt = (struct archdr *) skb_push(skb, hdr_size);
141
142	/*
143	 * Set the source hardware address.
144	 *
145	 * This is pretty pointless for most purposes, but it can help in
146	 * debugging.  ARCnet does not allow us to change the source address in
147	 * the actual packet sent)
148	 */
149	pkt->hard.source = *dev->dev_addr;
150
151	/* see linux/net/ethernet/eth.c to see where I got the following */
152
153	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
154		pkt->hard.dest = 0;
155		return hdr_size;
156	}
157	/* otherwise, just fill it in and go! */
158	pkt->hard.dest = daddr;
159
160	return hdr_size;	/* success */
161}
162
163
164static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
165		      int bufnum)
166{
167	struct arcnet_local *lp = dev->priv;
168	struct arc_hardware *hard = &pkt->hard;
169	int ofs;
170
171	BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
172	       lp->next_tx, lp->cur_tx, bufnum);
173
174	length -= ARC_HDR_SIZE;	/* hard header is not included in packet length */
175
176	if (length > XMTU) {
177		/* should never happen! other people already check for this. */
178		BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",
179		       length, XMTU);
180		length = XMTU;
181	}
182	if (length >= MinTU) {
183		hard->offset[0] = 0;
184		hard->offset[1] = ofs = 512 - length;
185	} else if (length > MTU) {
186		hard->offset[0] = 0;
187		hard->offset[1] = ofs = 512 - length - 3;
188	} else
189		hard->offset[0] = ofs = 256 - length;
190
191	BUGMSG(D_DURING, "prepare_tx: length=%d ofs=%d\n",
192	       length,ofs);
193
194	lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
195	lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
196
197	lp->lastload_dest = hard->dest;
198
199	return 1;		/* done */
200}
201