iwl4965: add comments to rate scaling code
[linux-2.6] / drivers / net / arcnet / rfc1201.c
1 /*
2  * Linux ARCnet driver - RFC1201 (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 #include <linux/module.h>
27 #include <linux/init.h>
28 #include <linux/if_arp.h>
29 #include <linux/netdevice.h>
30 #include <linux/skbuff.h>
31 #include <linux/arcdevice.h>
32
33 MODULE_LICENSE("GPL");
34 #define VERSION "arcnet: RFC1201 \"standard\" (`a') encapsulation support loaded.\n"
35
36
37 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
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 static int continue_tx(struct net_device *dev, int bufnum);
45
46 static struct ArcProto rfc1201_proto =
47 {
48         .suffix         = 'a',
49         .mtu            = 1500, /* could be more, but some receivers can't handle it... */
50         .is_ip          = 1,    /* This is for sending IP and ARP packages */
51         .rx             = rx,
52         .build_header   = build_header,
53         .prepare_tx     = prepare_tx,
54         .continue_tx    = continue_tx,
55         .ack_tx         = NULL
56 };
57
58
59 static int __init arcnet_rfc1201_init(void)
60 {
61         printk(VERSION);
62
63         arc_proto_map[ARC_P_IP]
64             = arc_proto_map[ARC_P_IPV6]
65             = arc_proto_map[ARC_P_ARP]
66             = arc_proto_map[ARC_P_RARP]
67             = arc_proto_map[ARC_P_IPX]
68             = arc_proto_map[ARC_P_NOVELL_EC]
69             = &rfc1201_proto;
70
71         /* if someone else already owns the broadcast, we won't take it */
72         if (arc_bcast_proto == arc_proto_default)
73                 arc_bcast_proto = &rfc1201_proto;
74
75         return 0;
76 }
77
78 static void __exit arcnet_rfc1201_exit(void)
79 {
80         arcnet_unregister_proto(&rfc1201_proto);
81 }
82
83 module_init(arcnet_rfc1201_init);
84 module_exit(arcnet_rfc1201_exit);
85
86 /*
87  * Determine a packet's protocol ID.
88  * 
89  * With ARCnet we have to convert everything to Ethernet-style stuff.
90  */
91 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
92 {
93         struct archdr *pkt = (struct archdr *) skb->data;
94         struct arc_rfc1201 *soft = &pkt->soft.rfc1201;
95         struct arcnet_local *lp = dev->priv;
96         int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;
97
98         /* Pull off the arcnet header. */
99         skb_reset_mac_header(skb);
100         skb_pull(skb, hdr_size);
101
102         if (pkt->hard.dest == 0)
103                 skb->pkt_type = PACKET_BROADCAST;
104         else if (dev->flags & IFF_PROMISC) {
105                 /* if we're not sending to ourselves :) */
106                 if (pkt->hard.dest != dev->dev_addr[0])
107                         skb->pkt_type = PACKET_OTHERHOST;
108         }
109         /* now return the protocol number */
110         switch (soft->proto) {
111         case ARC_P_IP:
112                 return htons(ETH_P_IP);
113         case ARC_P_IPV6:
114                 return htons(ETH_P_IPV6);
115         case ARC_P_ARP:
116                 return htons(ETH_P_ARP);
117         case ARC_P_RARP:
118                 return htons(ETH_P_RARP);
119
120         case ARC_P_IPX:
121         case ARC_P_NOVELL_EC:
122                 return htons(ETH_P_802_3);
123         default:
124                 lp->stats.rx_errors++;
125                 lp->stats.rx_crc_errors++;
126                 return 0;
127         }
128
129         return htons(ETH_P_IP);
130 }
131
132
133 /* packet receiver */
134 static void rx(struct net_device *dev, int bufnum,
135                struct archdr *pkthdr, int length)
136 {
137         struct arcnet_local *lp = dev->priv;
138         struct sk_buff *skb;
139         struct archdr *pkt = pkthdr;
140         struct arc_rfc1201 *soft = &pkthdr->soft.rfc1201;
141         int saddr = pkt->hard.source, ofs;
142         struct Incoming *in = &lp->rfc1201.incoming[saddr];
143
144         BUGMSG(D_DURING, "it's an RFC1201 packet (length=%d)\n", length);
145
146         if (length >= MinTU)
147                 ofs = 512 - length;
148         else
149                 ofs = 256 - length;
150
151         if (soft->split_flag == 0xFF) {         /* Exception Packet */
152                 if (length >= 4 + RFC1201_HDR_SIZE)
153                         BUGMSG(D_DURING, "compensating for exception packet\n");
154                 else {
155                         BUGMSG(D_EXTRA, "short RFC1201 exception packet from %02Xh",
156                                saddr);
157                         return;
158                 }
159
160                 /* skip over 4-byte junkola */
161                 length -= 4;
162                 ofs += 4;
163                 lp->hw.copy_from_card(dev, bufnum, 512 - length,
164                                       soft, sizeof(pkt->soft));
165         }
166         if (!soft->split_flag) {        /* not split */
167                 BUGMSG(D_RX, "incoming is not split (splitflag=%d)\n",
168                        soft->split_flag);
169
170                 if (in->skb) {  /* already assembling one! */
171                         BUGMSG(D_EXTRA, "aborting assembly (seq=%d) for unsplit packet (splitflag=%d, seq=%d)\n",
172                          in->sequence, soft->split_flag, soft->sequence);
173                         lp->rfc1201.aborted_seq = soft->sequence;
174                         dev_kfree_skb_irq(in->skb);
175                         lp->stats.rx_errors++;
176                         lp->stats.rx_missed_errors++;
177                         in->skb = NULL;
178                 }
179                 in->sequence = soft->sequence;
180
181                 skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
182                 if (skb == NULL) {
183                         BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");
184                         lp->stats.rx_dropped++;
185                         return;
186                 }
187                 skb_put(skb, length + ARC_HDR_SIZE);
188                 skb->dev = dev;
189
190                 pkt = (struct archdr *) skb->data;
191                 soft = &pkt->soft.rfc1201;
192
193                 /* up to sizeof(pkt->soft) has already been copied from the card */
194                 memcpy(pkt, pkthdr, sizeof(struct archdr));
195                 if (length > sizeof(pkt->soft))
196                         lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
197                                        pkt->soft.raw + sizeof(pkt->soft),
198                                               length - sizeof(pkt->soft));
199
200                 /*
201                  * ARP packets have problems when sent from some DOS systems: the
202                  * source address is always 0!  So we take the hardware source addr
203                  * (which is impossible to fumble) and insert it ourselves.
204                  */
205                 if (soft->proto == ARC_P_ARP) {
206                         struct arphdr *arp = (struct arphdr *) soft->payload;
207
208                         /* make sure addresses are the right length */
209                         if (arp->ar_hln == 1 && arp->ar_pln == 4) {
210                                 uint8_t *cptr = (uint8_t *) arp + sizeof(struct arphdr);
211
212                                 if (!*cptr) {   /* is saddr = 00? */
213                                         BUGMSG(D_EXTRA,
214                                                "ARP source address was 00h, set to %02Xh.\n",
215                                                saddr);
216                                         lp->stats.rx_crc_errors++;
217                                         *cptr = saddr;
218                                 } else {
219                                         BUGMSG(D_DURING, "ARP source address (%Xh) is fine.\n",
220                                                *cptr);
221                                 }
222                         } else {
223                                 BUGMSG(D_NORMAL, "funny-shaped ARP packet. (%Xh, %Xh)\n",
224                                        arp->ar_hln, arp->ar_pln);
225                                 lp->stats.rx_errors++;
226                                 lp->stats.rx_crc_errors++;
227                         }
228                 }
229                 BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "rx");
230
231                 skb->protocol = type_trans(skb, dev);
232                 netif_rx(skb);
233                 dev->last_rx = jiffies;
234         } else {                /* split packet */
235                 /*
236                  * NOTE: MSDOS ARP packet correction should only need to apply to
237                  * unsplit packets, since ARP packets are so short.
238                  *
239                  * My interpretation of the RFC1201 document is that if a packet is
240                  * received out of order, the entire assembly process should be
241                  * aborted.
242                  *
243                  * The RFC also mentions "it is possible for successfully received
244                  * packets to be retransmitted." As of 0.40 all previously received
245                  * packets are allowed, not just the most recent one.
246                  *
247                  * We allow multiple assembly processes, one for each ARCnet card
248                  * possible on the network.  Seems rather like a waste of memory,
249                  * but there's no other way to be reliable.
250                  */
251
252                 BUGMSG(D_RX, "packet is split (splitflag=%d, seq=%d)\n",
253                        soft->split_flag, in->sequence);
254
255                 if (in->skb && in->sequence != soft->sequence) {
256                         BUGMSG(D_EXTRA, "wrong seq number (saddr=%d, expected=%d, seq=%d, splitflag=%d)\n",
257                                saddr, in->sequence, soft->sequence,
258                                soft->split_flag);
259                         dev_kfree_skb_irq(in->skb);
260                         in->skb = NULL;
261                         lp->stats.rx_errors++;
262                         lp->stats.rx_missed_errors++;
263                         in->lastpacket = in->numpackets = 0;
264                 }
265                 if (soft->split_flag & 1) {     /* first packet in split */
266                         BUGMSG(D_RX, "brand new splitpacket (splitflag=%d)\n",
267                                soft->split_flag);
268                         if (in->skb) {  /* already assembling one! */
269                                 BUGMSG(D_EXTRA, "aborting previous (seq=%d) assembly "
270                                        "(splitflag=%d, seq=%d)\n",
271                                        in->sequence, soft->split_flag,
272                                        soft->sequence);
273                                 lp->stats.rx_errors++;
274                                 lp->stats.rx_missed_errors++;
275                                 dev_kfree_skb_irq(in->skb);
276                         }
277                         in->sequence = soft->sequence;
278                         in->numpackets = ((unsigned) soft->split_flag >> 1) + 2;
279                         in->lastpacket = 1;
280
281                         if (in->numpackets > 16) {
282                                 BUGMSG(D_EXTRA, "incoming packet more than 16 segments; dropping. (splitflag=%d)\n",
283                                        soft->split_flag);
284                                 lp->rfc1201.aborted_seq = soft->sequence;
285                                 lp->stats.rx_errors++;
286                                 lp->stats.rx_length_errors++;
287                                 return;
288                         }
289                         in->skb = skb = alloc_skb(508 * in->numpackets + ARC_HDR_SIZE,
290                                                   GFP_ATOMIC);
291                         if (skb == NULL) {
292                                 BUGMSG(D_NORMAL, "(split) memory squeeze, dropping packet.\n");
293                                 lp->rfc1201.aborted_seq = soft->sequence;
294                                 lp->stats.rx_dropped++;
295                                 return;
296                         }
297                         skb->dev = dev;
298                         pkt = (struct archdr *) skb->data;
299                         soft = &pkt->soft.rfc1201;
300
301                         memcpy(pkt, pkthdr, ARC_HDR_SIZE + RFC1201_HDR_SIZE);
302                         skb_put(skb, ARC_HDR_SIZE + RFC1201_HDR_SIZE);
303
304                         soft->split_flag = 0;   /* end result won't be split */
305                 } else {        /* not first packet */
306                         int packetnum = ((unsigned) soft->split_flag >> 1) + 1;
307
308                         /*
309                          * if we're not assembling, there's no point trying to
310                          * continue.
311                          */
312                         if (!in->skb) {
313                                 if (lp->rfc1201.aborted_seq != soft->sequence) {
314                                         BUGMSG(D_EXTRA, "can't continue split without starting "
315                                                "first! (splitflag=%d, seq=%d, aborted=%d)\n",
316                                         soft->split_flag, soft->sequence,
317                                                lp->rfc1201.aborted_seq);
318                                         lp->stats.rx_errors++;
319                                         lp->stats.rx_missed_errors++;
320                                 }
321                                 return;
322                         }
323                         in->lastpacket++;
324                         if (packetnum != in->lastpacket) {      /* not the right flag! */
325                                 /* harmless duplicate? ignore. */
326                                 if (packetnum <= in->lastpacket - 1) {
327                                         BUGMSG(D_EXTRA, "duplicate splitpacket ignored! (splitflag=%d)\n",
328                                                soft->split_flag);
329                                         lp->stats.rx_errors++;
330                                         lp->stats.rx_frame_errors++;
331                                         return;
332                                 }
333                                 /* "bad" duplicate, kill reassembly */
334                                 BUGMSG(D_EXTRA, "out-of-order splitpacket, reassembly "
335                                        "(seq=%d) aborted (splitflag=%d, seq=%d)\n",
336                                        in->sequence, soft->split_flag, soft->sequence);
337                                 lp->rfc1201.aborted_seq = soft->sequence;
338                                 dev_kfree_skb_irq(in->skb);
339                                 in->skb = NULL;
340                                 lp->stats.rx_errors++;
341                                 lp->stats.rx_missed_errors++;
342                                 in->lastpacket = in->numpackets = 0;
343                                 return;
344                         }
345                         pkt = (struct archdr *) in->skb->data;
346                         soft = &pkt->soft.rfc1201;
347                 }
348
349                 skb = in->skb;
350
351                 lp->hw.copy_from_card(dev, bufnum, ofs + RFC1201_HDR_SIZE,
352                                       skb->data + skb->len,
353                                       length - RFC1201_HDR_SIZE);
354                 skb_put(skb, length - RFC1201_HDR_SIZE);
355
356                 /* are we done? */
357                 if (in->lastpacket == in->numpackets) {
358                         in->skb = NULL;
359                         in->lastpacket = in->numpackets = 0;
360
361             BUGMSG(D_SKB_SIZE, "skb: received %d bytes from %02X (unsplit)\n",
362                 skb->len, pkt->hard.source);
363             BUGMSG(D_SKB_SIZE, "skb: received %d bytes from %02X (split)\n",
364                 skb->len, pkt->hard.source);
365                         BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "rx");
366
367                         skb->protocol = type_trans(skb, dev);
368                         netif_rx(skb);
369                         dev->last_rx = jiffies;
370                 }
371         }
372 }
373
374
375 /* Create the ARCnet hard/soft headers for RFC1201. */
376 static int build_header(struct sk_buff *skb, struct net_device *dev,
377                         unsigned short type, uint8_t daddr)
378 {
379         struct arcnet_local *lp = dev->priv;
380         int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;
381         struct archdr *pkt = (struct archdr *) skb_push(skb, hdr_size);
382         struct arc_rfc1201 *soft = &pkt->soft.rfc1201;
383
384         /* set the protocol ID according to RFC1201 */
385         switch (type) {
386         case ETH_P_IP:
387                 soft->proto = ARC_P_IP;
388                 break;
389         case ETH_P_IPV6:
390                 soft->proto = ARC_P_IPV6;
391                 break;
392         case ETH_P_ARP:
393                 soft->proto = ARC_P_ARP;
394                 break;
395         case ETH_P_RARP:
396                 soft->proto = ARC_P_RARP;
397                 break;
398         case ETH_P_IPX:
399         case ETH_P_802_3:
400         case ETH_P_802_2:
401                 soft->proto = ARC_P_IPX;
402                 break;
403         case ETH_P_ATALK:
404                 soft->proto = ARC_P_ATALK;
405                 break;
406         default:
407                 BUGMSG(D_NORMAL, "RFC1201: I don't understand protocol %d (%Xh)\n",
408                        type, type);
409                 lp->stats.tx_errors++;
410                 lp->stats.tx_aborted_errors++;
411                 return 0;
412         }
413
414         /*
415          * Set the source hardware address.
416          *
417          * This is pretty pointless for most purposes, but it can help in
418          * debugging.  ARCnet does not allow us to change the source address in
419          * the actual packet sent)
420          */
421         pkt->hard.source = *dev->dev_addr;
422
423         soft->sequence = htons(lp->rfc1201.sequence++);
424         soft->split_flag = 0;   /* split packets are done elsewhere */
425
426         /* see linux/net/ethernet/eth.c to see where I got the following */
427
428         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
429                 /* 
430                  * FIXME: fill in the last byte of the dest ipaddr here to better
431                  * comply with RFC1051 in "noarp" mode.  For now, always broadcasting
432                  * will probably at least get packets sent out :)
433                  */
434                 pkt->hard.dest = 0;
435                 return hdr_size;
436         }
437         /* otherwise, drop in the dest address */
438         pkt->hard.dest = daddr;
439         return hdr_size;
440 }
441
442
443 static void load_pkt(struct net_device *dev, struct arc_hardware *hard,
444                      struct arc_rfc1201 *soft, int softlen, int bufnum)
445 {
446         struct arcnet_local *lp = dev->priv;
447         int ofs;
448
449         /* assume length <= XMTU: someone should have handled that by now. */
450
451         if (softlen > MinTU) {
452                 hard->offset[0] = 0;
453                 hard->offset[1] = ofs = 512 - softlen;
454         } else if (softlen > MTU) {     /* exception packet - add an extra header */
455                 struct arc_rfc1201 excsoft;
456
457                 excsoft.proto = soft->proto;
458                 excsoft.split_flag = 0xff;
459                 excsoft.sequence = htons(0xffff);
460
461                 hard->offset[0] = 0;
462                 ofs = 512 - softlen;
463                 hard->offset[1] = ofs - RFC1201_HDR_SIZE;
464                 lp->hw.copy_to_card(dev, bufnum, ofs - RFC1201_HDR_SIZE,
465                                     &excsoft, RFC1201_HDR_SIZE);
466         } else
467                 hard->offset[0] = ofs = 256 - softlen;
468
469         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
470         lp->hw.copy_to_card(dev, bufnum, ofs, soft, softlen);
471
472         lp->lastload_dest = hard->dest;
473 }
474
475
476 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
477                       int bufnum)
478 {
479         struct arcnet_local *lp = dev->priv;
480         const int maxsegsize = XMTU - RFC1201_HDR_SIZE;
481         struct Outgoing *out;
482
483
484         BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
485                lp->next_tx, lp->cur_tx, bufnum);
486
487         length -= ARC_HDR_SIZE; /* hard header is not included in packet length */
488         pkt->soft.rfc1201.split_flag = 0;
489
490         /* need to do a split packet? */
491         if (length > XMTU) {
492                 out = &lp->outgoing;
493
494                 out->length = length - RFC1201_HDR_SIZE;
495                 out->dataleft = lp->outgoing.length;
496                 out->numsegs = (out->dataleft + maxsegsize - 1) / maxsegsize;
497                 out->segnum = 0;
498
499                 BUGMSG(D_DURING, "rfc1201 prep_tx: ready for %d-segment split "
500                        "(%d bytes, seq=%d)\n", out->numsegs, out->length,
501                        pkt->soft.rfc1201.sequence);
502
503                 return 0;       /* not done */
504         }
505         /* just load the packet into the buffers and send it off */
506         load_pkt(dev, &pkt->hard, &pkt->soft.rfc1201, length, bufnum);
507
508         return 1;               /* done */
509 }
510
511
512 static int continue_tx(struct net_device *dev, int bufnum)
513 {
514         struct arcnet_local *lp = dev->priv;
515         struct Outgoing *out = &lp->outgoing;
516         struct arc_hardware *hard = &out->pkt->hard;
517         struct arc_rfc1201 *soft = &out->pkt->soft.rfc1201, *newsoft;
518         int maxsegsize = XMTU - RFC1201_HDR_SIZE;
519         int seglen;
520
521         BUGMSG(D_DURING,
522           "rfc1201 continue_tx: loading segment %d(+1) of %d (seq=%d)\n",
523                out->segnum, out->numsegs, soft->sequence);
524
525         /* the "new" soft header comes right before the data chunk */
526         newsoft = (struct arc_rfc1201 *)
527             (out->pkt->soft.raw + out->length - out->dataleft);
528
529         if (!out->segnum)       /* first packet; newsoft == soft */
530                 newsoft->split_flag = ((out->numsegs - 2) << 1) | 1;
531         else {
532                 newsoft->split_flag = out->segnum << 1;
533                 newsoft->proto = soft->proto;
534                 newsoft->sequence = soft->sequence;
535         }
536
537         seglen = maxsegsize;
538         if (seglen > out->dataleft)
539                 seglen = out->dataleft;
540         out->dataleft -= seglen;
541
542         load_pkt(dev, hard, newsoft, seglen + RFC1201_HDR_SIZE, bufnum);
543
544         out->segnum++;
545         if (out->segnum >= out->numsegs)
546                 return 1;
547         else
548                 return 0;
549 }