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#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#include "arcdevice.h"
37
38/* packet receiver */
39static void rx(struct net_device *dev, int bufnum,
40	       struct archdr *pkthdr, int length)
41{
42	struct arcnet_local *lp = netdev_priv(dev);
43	struct sk_buff *skb;
44	struct archdr *pkt = pkthdr;
45	int ofs;
46
47	arc_printk(D_DURING, dev, "it's a raw packet (length=%d)\n", length);
48
49	if (length > MTU)
50		ofs = 512 - length;
51	else
52		ofs = 256 - length;
53
54	skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
55	if (!skb) {
56		dev->stats.rx_dropped++;
57		return;
58	}
59	skb_put(skb, length + ARC_HDR_SIZE);
60	skb->dev = dev;
61
62	pkt = (struct archdr *)skb->data;
63
64	skb_reset_mac_header(skb);
65	skb_pull(skb, ARC_HDR_SIZE);
66
67	/* up to sizeof(pkt->soft) has already been copied from the card */
68	memcpy(pkt, pkthdr, sizeof(struct archdr));
69	if (length > sizeof(pkt->soft))
70		lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
71				      pkt->soft.raw + sizeof(pkt->soft),
72				      length - sizeof(pkt->soft));
73
74	if (BUGLVL(D_SKB))
75		arcnet_dump_skb(dev, skb, "rx");
76
77	skb->protocol = cpu_to_be16(ETH_P_ARCNET);
78	netif_rx(skb);
79}
80
81/* Create the ARCnet hard/soft headers for raw mode.
82 * There aren't any soft headers in raw mode - not even the protocol id.
83 */
84static int build_header(struct sk_buff *skb, struct net_device *dev,
85			unsigned short type, uint8_t daddr)
86{
87	int hdr_size = ARC_HDR_SIZE;
88	struct archdr *pkt = skb_push(skb, hdr_size);
89
90	/* Set the source hardware address.
91	 *
92	 * This is pretty pointless for most purposes, but it can help in
93	 * debugging.  ARCnet does not allow us to change the source address
94	 * in the actual packet sent.
95	 */
96	pkt->hard.source = *dev->dev_addr;
97
98	/* see linux/net/ethernet/eth.c to see where I got the following */
99
100	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
101		/* FIXME: fill in the last byte of the dest ipaddr here
102		 * to better comply with RFC1051 in "noarp" mode.
103		 */
104		pkt->hard.dest = 0;
105		return hdr_size;
106	}
107	/* otherwise, just fill it in and go! */
108	pkt->hard.dest = daddr;
109
110	return hdr_size;	/* success */
111}
112
113static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
114		      int bufnum)
115{
116	struct arcnet_local *lp = netdev_priv(dev);
117	struct arc_hardware *hard = &pkt->hard;
118	int ofs;
119
120	arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
121		   lp->next_tx, lp->cur_tx, bufnum);
122
123	/* hard header is not included in packet length */
124	length -= ARC_HDR_SIZE;
125
126	if (length > XMTU) {
127		/* should never happen! other people already check for this. */
128		arc_printk(D_NORMAL, dev, "Bug!  prepare_tx with size %d (> %d)\n",
129			   length, XMTU);
130		length = XMTU;
131	}
132	if (length >= MinTU) {
133		hard->offset[0] = 0;
134		hard->offset[1] = ofs = 512 - length;
135	} else if (length > MTU) {
136		hard->offset[0] = 0;
137		hard->offset[1] = ofs = 512 - length - 3;
138	} else {
139		hard->offset[0] = ofs = 256 - length;
140	}
141
142	arc_printk(D_DURING, dev, "prepare_tx: length=%d ofs=%d\n",
143		   length, ofs);
144
145	lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
146	lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
147
148	lp->lastload_dest = hard->dest;
149
150	return 1;		/* done */
151}
152
153static struct ArcProto rawmode_proto = {
154	.suffix		= 'r',
155	.mtu		= XMTU,
156	.rx		= rx,
157	.build_header	= build_header,
158	.prepare_tx	= prepare_tx,
159	.continue_tx    = NULL,
160	.ack_tx         = NULL
161};
162
163static int __init arcnet_raw_init(void)
164{
165	int count;
166
167	pr_info("raw mode (`r') encapsulation support loaded\n");
168
169	for (count = 0; count < 256; count++)
170		if (arc_proto_map[count] == arc_proto_default)
171			arc_proto_map[count] = &rawmode_proto;
172
173	/* for raw mode, we only set the bcast proto if there's no better one */
174	if (arc_bcast_proto == arc_proto_default)
175		arc_bcast_proto = &rawmode_proto;
176
177	arc_proto_default = &rawmode_proto;
178	return 0;
179}
180
181static void __exit arcnet_raw_exit(void)
182{
183	arcnet_unregister_proto(&rawmode_proto);
184}
185
186module_init(arcnet_raw_init);
187module_exit(arcnet_raw_exit);
188
189MODULE_DESCRIPTION("ARCnet raw mode packet interface module");
190MODULE_LICENSE("GPL");
191