xref: /openbmc/linux/drivers/net/arcnet/capmode.c (revision 77afe3b8)
1 /*
2  * Linux ARCnet driver - "cap mode" packet encapsulation.
3  * It adds sequence numbers to packets for communicating between a user space
4  * application and the driver. After a transmit it sends a packet with protocol
5  * byte 0 back up to the userspace containing the sequence number of the packet
6  * plus the transmit-status on the ArcNet.
7  *
8  * Written 2002-4 by Esben Nielsen, Vestas Wind Systems A/S
9  * Derived from arc-rawmode.c by Avery Pennarun.
10  * arc-rawmode was in turned based on skeleton.c, see below.
11  *
12  * **********************
13  *
14  * The original copyright of skeleton.c was as follows:
15  *
16  * skeleton.c Written 1993 by Donald Becker.
17  * Copyright 1993 United States Government as represented by the
18  * Director, National Security Agency.  This software may only be used
19  * and distributed according to the terms of the GNU General Public License as
20  * modified by SRC, incorporated herein by reference.
21  *
22  * **********************
23  *
24  * For more details, see drivers/net/arcnet.c
25  *
26  * **********************
27  */
28 
29 #define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
30 
31 #include <linux/module.h>
32 #include <linux/gfp.h>
33 #include <linux/init.h>
34 #include <linux/if_arp.h>
35 #include <net/arp.h>
36 #include <linux/netdevice.h>
37 #include <linux/skbuff.h>
38 
39 #include "arcdevice.h"
40 
41 /* packet receiver */
rx(struct net_device * dev,int bufnum,struct archdr * pkthdr,int length)42 static void rx(struct net_device *dev, int bufnum,
43 	       struct archdr *pkthdr, int length)
44 {
45 	struct arcnet_local *lp = netdev_priv(dev);
46 	struct sk_buff *skb;
47 	struct archdr *pkt;
48 	char *pktbuf, *pkthdrbuf;
49 	int ofs;
50 
51 	arc_printk(D_DURING, dev, "it's a raw(cap) packet (length=%d)\n",
52 		   length);
53 
54 	if (length >= MinTU)
55 		ofs = 512 - length;
56 	else
57 		ofs = 256 - length;
58 
59 	skb = alloc_skb(length + ARC_HDR_SIZE + sizeof(int), GFP_ATOMIC);
60 	if (!skb) {
61 		dev->stats.rx_dropped++;
62 		return;
63 	}
64 	skb_put(skb, length + ARC_HDR_SIZE + sizeof(int));
65 	skb->dev = dev;
66 	skb_reset_mac_header(skb);
67 	pkt = (struct archdr *)skb_mac_header(skb);
68 	skb_pull(skb, ARC_HDR_SIZE);
69 
70 	/* up to sizeof(pkt->soft) has already been copied from the card
71 	 * squeeze in an int for the cap encapsulation
72 	 * use these variables to be sure we count in bytes, not in
73 	 * sizeof(struct archdr)
74 	 */
75 	pktbuf = (char *)pkt;
76 	pkthdrbuf = (char *)pkthdr;
77 	memcpy(pktbuf, pkthdrbuf, ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto));
78 	memcpy(pktbuf + ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto) + sizeof(int),
79 	       pkthdrbuf + ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto),
80 	       sizeof(struct archdr) - ARC_HDR_SIZE - sizeof(pkt->soft.cap.proto));
81 
82 	if (length > sizeof(pkt->soft))
83 		lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
84 				      pkt->soft.raw + sizeof(pkt->soft)
85 				      + sizeof(int),
86 				      length - sizeof(pkt->soft));
87 
88 	if (BUGLVL(D_SKB))
89 		arcnet_dump_skb(dev, skb, "rx");
90 
91 	skb->protocol = cpu_to_be16(ETH_P_ARCNET);
92 	netif_rx(skb);
93 }
94 
95 /* Create the ARCnet hard/soft headers for cap mode.
96  * There aren't any soft headers in cap mode - not even the protocol id.
97  */
build_header(struct sk_buff * skb,struct net_device * dev,unsigned short type,uint8_t daddr)98 static int build_header(struct sk_buff *skb,
99 			struct net_device *dev,
100 			unsigned short type,
101 			uint8_t daddr)
102 {
103 	int hdr_size = ARC_HDR_SIZE;
104 	struct archdr *pkt = skb_push(skb, hdr_size);
105 
106 	arc_printk(D_PROTO, dev, "Preparing header for cap packet %x.\n",
107 		   *((int *)&pkt->soft.cap.cookie[0]));
108 
109 	/* Set the source hardware address.
110 	 *
111 	 * This is pretty pointless for most purposes, but it can help in
112 	 * debugging.  ARCnet does not allow us to change the source address in
113 	 * the actual packet sent)
114 	 */
115 	pkt->hard.source = *dev->dev_addr;
116 
117 	/* see linux/net/ethernet/eth.c to see where I got the following */
118 
119 	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
120 		/* FIXME: fill in the last byte of the dest ipaddr here to
121 		 * better comply with RFC1051 in "noarp" mode.
122 		 */
123 		pkt->hard.dest = 0;
124 		return hdr_size;
125 	}
126 	/* otherwise, just fill it in and go! */
127 	pkt->hard.dest = daddr;
128 
129 	return hdr_size;	/* success */
130 }
131 
prepare_tx(struct net_device * dev,struct archdr * pkt,int length,int bufnum)132 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
133 		      int bufnum)
134 {
135 	struct arcnet_local *lp = netdev_priv(dev);
136 	struct arc_hardware *hard = &pkt->hard;
137 	int ofs;
138 
139 	/* hard header is not included in packet length */
140 	length -= ARC_HDR_SIZE;
141 	/* And neither is the cookie field */
142 	length -= sizeof(int);
143 
144 	arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
145 		   lp->next_tx, lp->cur_tx, bufnum);
146 
147 	arc_printk(D_PROTO, dev, "Sending for cap packet %x.\n",
148 		   *((int *)&pkt->soft.cap.cookie[0]));
149 
150 	if (length > XMTU) {
151 		/* should never happen! other people already check for this. */
152 		arc_printk(D_NORMAL, dev, "Bug!  prepare_tx with size %d (> %d)\n",
153 			   length, XMTU);
154 		length = XMTU;
155 	}
156 	if (length > MinTU) {
157 		hard->offset[0] = 0;
158 		hard->offset[1] = ofs = 512 - length;
159 	} else if (length > MTU) {
160 		hard->offset[0] = 0;
161 		hard->offset[1] = ofs = 512 - length - 3;
162 	} else {
163 		hard->offset[0] = ofs = 256 - length;
164 	}
165 
166 	arc_printk(D_DURING, dev, "prepare_tx: length=%d ofs=%d\n",
167 		   length, ofs);
168 
169 	/* Copy the arcnet-header + the protocol byte down: */
170 	lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
171 	lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft.cap.proto,
172 			    sizeof(pkt->soft.cap.proto));
173 
174 	/* Skip the extra integer we have written into it as a cookie
175 	 * but write the rest of the message:
176 	 */
177 	lp->hw.copy_to_card(dev, bufnum, ofs + 1,
178 			    ((unsigned char *)&pkt->soft.cap.mes), length - 1);
179 
180 	lp->lastload_dest = hard->dest;
181 
182 	return 1;	/* done */
183 }
184 
ack_tx(struct net_device * dev,int acked)185 static int ack_tx(struct net_device *dev, int acked)
186 {
187 	struct arcnet_local *lp = netdev_priv(dev);
188 	struct sk_buff *ackskb;
189 	struct archdr *ackpkt;
190 	int length = sizeof(struct arc_cap);
191 
192 	arc_printk(D_DURING, dev, "capmode: ack_tx: protocol: %x: result: %d\n",
193 		   lp->outgoing.skb->protocol, acked);
194 
195 	if (BUGLVL(D_SKB))
196 		arcnet_dump_skb(dev, lp->outgoing.skb, "ack_tx");
197 
198 	/* Now alloc a skb to send back up through the layers: */
199 	ackskb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
200 	if (!ackskb)
201 		goto free_outskb;
202 
203 	skb_put(ackskb, length + ARC_HDR_SIZE);
204 	ackskb->dev = dev;
205 
206 	skb_reset_mac_header(ackskb);
207 	ackpkt = (struct archdr *)skb_mac_header(ackskb);
208 	/* skb_pull(ackskb, ARC_HDR_SIZE); */
209 
210 	skb_copy_from_linear_data(lp->outgoing.skb, ackpkt,
211 				  ARC_HDR_SIZE + sizeof(struct arc_cap));
212 	ackpkt->soft.cap.proto = 0; /* using protocol 0 for acknowledge */
213 	ackpkt->soft.cap.mes.ack = acked;
214 
215 	arc_printk(D_PROTO, dev, "Acknowledge for cap packet %x.\n",
216 		   *((int *)&ackpkt->soft.cap.cookie[0]));
217 
218 	ackskb->protocol = cpu_to_be16(ETH_P_ARCNET);
219 
220 	if (BUGLVL(D_SKB))
221 		arcnet_dump_skb(dev, ackskb, "ack_tx_recv");
222 	netif_rx(ackskb);
223 
224 free_outskb:
225 	dev_kfree_skb_irq(lp->outgoing.skb);
226 	lp->outgoing.proto = NULL;
227 			/* We are always finished when in this protocol */
228 
229 	return 0;
230 }
231 
232 static struct ArcProto capmode_proto = {
233 	.suffix		= 'r',
234 	.mtu		= XMTU,
235 	.rx		= rx,
236 	.build_header	= build_header,
237 	.prepare_tx	= prepare_tx,
238 	.ack_tx		= ack_tx
239 };
240 
capmode_module_init(void)241 static int __init capmode_module_init(void)
242 {
243 	int count;
244 
245 	pr_info("cap mode (`c') encapsulation support loaded\n");
246 
247 	for (count = 1; count <= 8; count++)
248 		if (arc_proto_map[count] == arc_proto_default)
249 			arc_proto_map[count] = &capmode_proto;
250 
251 	/* for cap mode, we only set the bcast proto if there's no better one */
252 	if (arc_bcast_proto == arc_proto_default)
253 		arc_bcast_proto = &capmode_proto;
254 
255 	arc_proto_default = &capmode_proto;
256 	arc_raw_proto = &capmode_proto;
257 
258 	return 0;
259 }
260 
capmode_module_exit(void)261 static void __exit capmode_module_exit(void)
262 {
263 	arcnet_unregister_proto(&capmode_proto);
264 }
265 module_init(capmode_module_init);
266 module_exit(capmode_module_exit);
267 
268 MODULE_LICENSE("GPL");
269