xref: /openbmc/linux/drivers/net/arcnet/arc-rawmode.c (revision b6dcefde)
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 
38 static void rx(struct net_device *dev, int bufnum,
39 	       struct archdr *pkthdr, int length);
40 static int build_header(struct sk_buff *skb, struct net_device *dev,
41 			unsigned short type, uint8_t daddr);
42 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
43 		      int bufnum);
44 
45 static 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 
57 static 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 
75 static void __exit arcnet_raw_exit(void)
76 {
77 	arcnet_unregister_proto(&rawmode_proto);
78 }
79 
80 module_init(arcnet_raw_init);
81 module_exit(arcnet_raw_exit);
82 
83 MODULE_LICENSE("GPL");
84 
85 
86 /* packet receiver */
87 static void rx(struct net_device *dev, int bufnum,
88 	       struct archdr *pkthdr, int length)
89 {
90 	struct arcnet_local *lp = netdev_priv(dev);
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 		dev->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 = cpu_to_be16(ETH_P_ARCNET);
126 	netif_rx(skb);
127 }
128 
129 
130 /*
131  * Create the ARCnet hard/soft headers for raw mode.
132  * There aren't any soft headers in raw mode - not even the protocol id.
133  */
134 static int build_header(struct sk_buff *skb, struct net_device *dev,
135 			unsigned short type, uint8_t daddr)
136 {
137 	int hdr_size = ARC_HDR_SIZE;
138 	struct archdr *pkt = (struct archdr *) skb_push(skb, hdr_size);
139 
140 	/*
141 	 * Set the source hardware address.
142 	 *
143 	 * This is pretty pointless for most purposes, but it can help in
144 	 * debugging.  ARCnet does not allow us to change the source address in
145 	 * the actual packet sent)
146 	 */
147 	pkt->hard.source = *dev->dev_addr;
148 
149 	/* see linux/net/ethernet/eth.c to see where I got the following */
150 
151 	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
152 		/*
153 		 * FIXME: fill in the last byte of the dest ipaddr here to better
154 		 * comply with RFC1051 in "noarp" mode.
155 		 */
156 		pkt->hard.dest = 0;
157 		return hdr_size;
158 	}
159 	/* otherwise, just fill it in and go! */
160 	pkt->hard.dest = daddr;
161 
162 	return hdr_size;	/* success */
163 }
164 
165 
166 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
167 		      int bufnum)
168 {
169 	struct arcnet_local *lp = netdev_priv(dev);
170 	struct arc_hardware *hard = &pkt->hard;
171 	int ofs;
172 
173 	BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
174 	       lp->next_tx, lp->cur_tx, bufnum);
175 
176 	length -= ARC_HDR_SIZE;	/* hard header is not included in packet length */
177 
178 	if (length > XMTU) {
179 		/* should never happen! other people already check for this. */
180 		BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",
181 		       length, XMTU);
182 		length = XMTU;
183 	}
184 	if (length >= MinTU) {
185 		hard->offset[0] = 0;
186 		hard->offset[1] = ofs = 512 - length;
187 	} else if (length > MTU) {
188 		hard->offset[0] = 0;
189 		hard->offset[1] = ofs = 512 - length - 3;
190 	} else
191 		hard->offset[0] = ofs = 256 - length;
192 
193 	BUGMSG(D_DURING, "prepare_tx: length=%d ofs=%d\n",
194 	       length,ofs);
195 
196 	lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
197 	lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
198 
199 	lp->lastload_dest = hard->dest;
200 
201 	return 1;		/* done */
202 }
203