1/*
2 * Linux ARCnet driver - RFC1051 ("simple" standard) packet encapsulation
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#define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
28
29#include <linux/module.h>
30#include <linux/gfp.h>
31#include <linux/init.h>
32#include <linux/if_arp.h>
33#include <net/arp.h>
34#include <linux/netdevice.h>
35#include <linux/skbuff.h>
36
37#include "arcdevice.h"
38
39static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
40static void rx(struct net_device *dev, int bufnum,
41 struct archdr *pkthdr, int length);
42static int build_header(struct sk_buff *skb, struct net_device *dev,
43 unsigned short type, uint8_t daddr);
44static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
45 int bufnum);
46
47static struct ArcProto rfc1051_proto = {
48 .suffix = 's',
49 .mtu = XMTU - RFC1051_HDR_SIZE,
50 .is_ip = 1,
51 .rx = rx,
52 .build_header = build_header,
53 .prepare_tx = prepare_tx,
54 .continue_tx = NULL,
55 .ack_tx = NULL
56};
57
58static int __init arcnet_rfc1051_init(void)
59{
60 pr_info("%s\n", "RFC1051 \"simple standard\" (`s') encapsulation support loaded");
61
62 arc_proto_map[ARC_P_IP_RFC1051]
63 = arc_proto_map[ARC_P_ARP_RFC1051]
64 = &rfc1051_proto;
65
66 /* if someone else already owns the broadcast, we won't take it */
67 if (arc_bcast_proto == arc_proto_default)
68 arc_bcast_proto = &rfc1051_proto;
69
70 return 0;
71}
72
73static void __exit arcnet_rfc1051_exit(void)
74{
75 arcnet_unregister_proto(proto: &rfc1051_proto);
76}
77
78module_init(arcnet_rfc1051_init);
79module_exit(arcnet_rfc1051_exit);
80
81MODULE_DESCRIPTION("ARCNet packet format (RFC 1051) module");
82MODULE_LICENSE("GPL");
83
84/* Determine a packet's protocol ID.
85 *
86 * With ARCnet we have to convert everything to Ethernet-style stuff.
87 */
88static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
89{
90 struct archdr *pkt = (struct archdr *)skb->data;
91 struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
92 int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
93
94 /* Pull off the arcnet header. */
95 skb_reset_mac_header(skb);
96 skb_pull(skb, len: hdr_size);
97
98 if (pkt->hard.dest == 0) {
99 skb->pkt_type = PACKET_BROADCAST;
100 } else if (dev->flags & IFF_PROMISC) {
101 /* if we're not sending to ourselves :) */
102 if (pkt->hard.dest != dev->dev_addr[0])
103 skb->pkt_type = PACKET_OTHERHOST;
104 }
105 /* now return the protocol number */
106 switch (soft->proto) {
107 case ARC_P_IP_RFC1051:
108 return htons(ETH_P_IP);
109 case ARC_P_ARP_RFC1051:
110 return htons(ETH_P_ARP);
111
112 default:
113 dev->stats.rx_errors++;
114 dev->stats.rx_crc_errors++;
115 return 0;
116 }
117
118 return htons(ETH_P_IP);
119}
120
121/* packet receiver */
122static void rx(struct net_device *dev, int bufnum,
123 struct archdr *pkthdr, int length)
124{
125 struct arcnet_local *lp = netdev_priv(dev);
126 struct sk_buff *skb;
127 struct archdr *pkt = pkthdr;
128 int ofs;
129
130 arc_printk(D_DURING, dev, "it's a raw packet (length=%d)\n", length);
131
132 if (length >= MinTU)
133 ofs = 512 - length;
134 else
135 ofs = 256 - length;
136
137 skb = alloc_skb(size: length + ARC_HDR_SIZE, GFP_ATOMIC);
138 if (!skb) {
139 dev->stats.rx_dropped++;
140 return;
141 }
142 skb_put(skb, len: length + ARC_HDR_SIZE);
143 skb->dev = dev;
144
145 pkt = (struct archdr *)skb->data;
146
147 /* up to sizeof(pkt->soft) has already been copied from the card */
148 memcpy(pkt, pkthdr, sizeof(struct archdr));
149 if (length > sizeof(pkt->soft))
150 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
151 pkt->soft.raw + sizeof(pkt->soft),
152 length - sizeof(pkt->soft));
153
154 if (BUGLVL(D_SKB))
155 arcnet_dump_skb(dev, skb, desc: "rx");
156
157 skb->protocol = type_trans(skb, dev);
158 netif_rx(skb);
159}
160
161/* Create the ARCnet hard/soft headers for RFC1051 */
162static int build_header(struct sk_buff *skb, struct net_device *dev,
163 unsigned short type, uint8_t daddr)
164{
165 int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
166 struct archdr *pkt = skb_push(skb, len: hdr_size);
167 struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
168
169 /* set the protocol ID according to RFC1051 */
170 switch (type) {
171 case ETH_P_IP:
172 soft->proto = ARC_P_IP_RFC1051;
173 break;
174 case ETH_P_ARP:
175 soft->proto = ARC_P_ARP_RFC1051;
176 break;
177 default:
178 arc_printk(D_NORMAL, dev, "RFC1051: I don't understand protocol %d (%Xh)\n",
179 type, type);
180 dev->stats.tx_errors++;
181 dev->stats.tx_aborted_errors++;
182 return 0;
183 }
184
185 /* Set the source hardware address.
186 *
187 * This is pretty pointless for most purposes, but it can help in
188 * debugging. ARCnet does not allow us to change the source address
189 * in the actual packet sent.
190 */
191 pkt->hard.source = *dev->dev_addr;
192
193 /* see linux/net/ethernet/eth.c to see where I got the following */
194
195 if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
196 /* FIXME: fill in the last byte of the dest ipaddr here to
197 * better comply with RFC1051 in "noarp" mode.
198 */
199 pkt->hard.dest = 0;
200 return hdr_size;
201 }
202 /* otherwise, just fill it in and go! */
203 pkt->hard.dest = daddr;
204
205 return hdr_size; /* success */
206}
207
208static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
209 int bufnum)
210{
211 struct arcnet_local *lp = netdev_priv(dev);
212 struct arc_hardware *hard = &pkt->hard;
213 int ofs;
214
215 arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
216 lp->next_tx, lp->cur_tx, bufnum);
217
218 /* hard header is not included in packet length */
219 length -= ARC_HDR_SIZE;
220
221 if (length > XMTU) {
222 /* should never happen! other people already check for this. */
223 arc_printk(D_NORMAL, dev, "Bug! prepare_tx with size %d (> %d)\n",
224 length, XMTU);
225 length = XMTU;
226 }
227 if (length > MinTU) {
228 hard->offset[0] = 0;
229 hard->offset[1] = ofs = 512 - length;
230 } else if (length > MTU) {
231 hard->offset[0] = 0;
232 hard->offset[1] = ofs = 512 - length - 3;
233 } else {
234 hard->offset[0] = ofs = 256 - length;
235 }
236
237 lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
238 lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
239
240 lp->lastload_dest = hard->dest;
241
242 return 1; /* done */
243}
244

source code of linux/drivers/net/arcnet/rfc1051.c