Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /********************************************************************* |
| 2 | * |
| 3 | * Filename: wrapper.c |
| 4 | * Version: 1.2 |
| 5 | * Description: IrDA SIR async wrapper layer |
| 6 | * Status: Stable |
| 7 | * Author: Dag Brattli <dagb@cs.uit.no> |
| 8 | * Created at: Mon Aug 4 20:40:53 1997 |
| 9 | * Modified at: Fri Jan 28 13:21:09 2000 |
| 10 | * Modified by: Dag Brattli <dagb@cs.uit.no> |
| 11 | * Modified at: Fri May 28 3:11 CST 1999 |
| 12 | * Modified by: Horst von Brand <vonbrand@sleipnir.valparaiso.cl> |
| 13 | * |
| 14 | * Copyright (c) 1998-2000 Dag Brattli <dagb@cs.uit.no>, |
| 15 | * All Rights Reserved. |
| 16 | * Copyright (c) 2000-2002 Jean Tourrilhes <jt@hpl.hp.com> |
| 17 | * |
| 18 | * This program is free software; you can redistribute it and/or |
| 19 | * modify it under the terms of the GNU General Public License as |
| 20 | * published by the Free Software Foundation; either version 2 of |
| 21 | * the License, or (at your option) any later version. |
| 22 | * |
| 23 | * Neither Dag Brattli nor University of Tromsø admit liability nor |
| 24 | * provide warranty for any of this software. This material is |
| 25 | * provided "AS-IS" and at no charge. |
| 26 | * |
| 27 | ********************************************************************/ |
| 28 | |
| 29 | #include <linux/skbuff.h> |
| 30 | #include <linux/string.h> |
| 31 | #include <linux/module.h> |
| 32 | #include <asm/byteorder.h> |
| 33 | |
| 34 | #include <net/irda/irda.h> |
| 35 | #include <net/irda/wrapper.h> |
| 36 | #include <net/irda/crc.h> |
| 37 | #include <net/irda/irlap.h> |
| 38 | #include <net/irda/irlap_frame.h> |
| 39 | #include <net/irda/irda_device.h> |
| 40 | |
| 41 | /************************** FRAME WRAPPING **************************/ |
| 42 | /* |
| 43 | * Unwrap and unstuff SIR frames |
| 44 | * |
| 45 | * Note : at FIR and MIR, HDLC framing is used and usually handled |
| 46 | * by the controller, so we come here only for SIR... Jean II |
| 47 | */ |
| 48 | |
| 49 | /* |
| 50 | * Function stuff_byte (byte, buf) |
| 51 | * |
| 52 | * Byte stuff one single byte and put the result in buffer pointed to by |
| 53 | * buf. The buffer must at all times be able to have two bytes inserted. |
| 54 | * |
| 55 | * This is in a tight loop, better inline it, so need to be prior to callers. |
| 56 | * (2000 bytes on P6 200MHz, non-inlined ~370us, inline ~170us) - Jean II |
| 57 | */ |
| 58 | static inline int stuff_byte(__u8 byte, __u8 *buf) |
| 59 | { |
| 60 | switch (byte) { |
| 61 | case BOF: /* FALLTHROUGH */ |
| 62 | case EOF: /* FALLTHROUGH */ |
| 63 | case CE: |
| 64 | /* Insert transparently coded */ |
| 65 | buf[0] = CE; /* Send link escape */ |
| 66 | buf[1] = byte^IRDA_TRANS; /* Complement bit 5 */ |
| 67 | return 2; |
| 68 | /* break; */ |
| 69 | default: |
| 70 | /* Non-special value, no transparency required */ |
| 71 | buf[0] = byte; |
| 72 | return 1; |
| 73 | /* break; */ |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | /* |
| 78 | * Function async_wrap (skb, *tx_buff, buffsize) |
| 79 | * |
| 80 | * Makes a new buffer with wrapping and stuffing, should check that |
| 81 | * we don't get tx buffer overflow. |
| 82 | */ |
| 83 | int async_wrap_skb(struct sk_buff *skb, __u8 *tx_buff, int buffsize) |
| 84 | { |
| 85 | struct irda_skb_cb *cb = (struct irda_skb_cb *) skb->cb; |
| 86 | int xbofs; |
| 87 | int i; |
| 88 | int n; |
| 89 | union { |
| 90 | __u16 value; |
| 91 | __u8 bytes[2]; |
| 92 | } fcs; |
| 93 | |
| 94 | /* Initialize variables */ |
| 95 | fcs.value = INIT_FCS; |
| 96 | n = 0; |
| 97 | |
| 98 | /* |
| 99 | * Send XBOF's for required min. turn time and for the negotiated |
| 100 | * additional XBOFS |
| 101 | */ |
| 102 | |
| 103 | if (cb->magic != LAP_MAGIC) { |
| 104 | /* |
| 105 | * This will happen for all frames sent from user-space. |
| 106 | * Nothing to worry about, but we set the default number of |
| 107 | * BOF's |
| 108 | */ |
| 109 | IRDA_DEBUG(1, "%s(), wrong magic in skb!\n", __FUNCTION__); |
| 110 | xbofs = 10; |
| 111 | } else |
| 112 | xbofs = cb->xbofs + cb->xbofs_delay; |
| 113 | |
| 114 | IRDA_DEBUG(4, "%s(), xbofs=%d\n", __FUNCTION__, xbofs); |
| 115 | |
| 116 | /* Check that we never use more than 115 + 48 xbofs */ |
| 117 | if (xbofs > 163) { |
| 118 | IRDA_DEBUG(0, "%s(), too many xbofs (%d)\n", __FUNCTION__, |
| 119 | xbofs); |
| 120 | xbofs = 163; |
| 121 | } |
| 122 | |
| 123 | memset(tx_buff + n, XBOF, xbofs); |
| 124 | n += xbofs; |
| 125 | |
| 126 | /* Start of packet character BOF */ |
| 127 | tx_buff[n++] = BOF; |
| 128 | |
| 129 | /* Insert frame and calc CRC */ |
| 130 | for (i=0; i < skb->len; i++) { |
| 131 | /* |
| 132 | * Check for the possibility of tx buffer overflow. We use |
| 133 | * bufsize-5 since the maximum number of bytes that can be |
| 134 | * transmitted after this point is 5. |
| 135 | */ |
| 136 | if(n >= (buffsize-5)) { |
| 137 | IRDA_ERROR("%s(), tx buffer overflow (n=%d)\n", |
| 138 | __FUNCTION__, n); |
| 139 | return n; |
| 140 | } |
| 141 | |
| 142 | n += stuff_byte(skb->data[i], tx_buff+n); |
| 143 | fcs.value = irda_fcs(fcs.value, skb->data[i]); |
| 144 | } |
| 145 | |
| 146 | /* Insert CRC in little endian format (LSB first) */ |
| 147 | fcs.value = ~fcs.value; |
| 148 | #ifdef __LITTLE_ENDIAN |
| 149 | n += stuff_byte(fcs.bytes[0], tx_buff+n); |
| 150 | n += stuff_byte(fcs.bytes[1], tx_buff+n); |
| 151 | #else /* ifdef __BIG_ENDIAN */ |
| 152 | n += stuff_byte(fcs.bytes[1], tx_buff+n); |
| 153 | n += stuff_byte(fcs.bytes[0], tx_buff+n); |
| 154 | #endif |
| 155 | tx_buff[n++] = EOF; |
| 156 | |
| 157 | return n; |
| 158 | } |
| 159 | EXPORT_SYMBOL(async_wrap_skb); |
| 160 | |
| 161 | /************************* FRAME UNWRAPPING *************************/ |
| 162 | /* |
| 163 | * Unwrap and unstuff SIR frames |
| 164 | * |
| 165 | * Complete rewrite by Jean II : |
| 166 | * More inline, faster, more compact, more logical. Jean II |
| 167 | * (16 bytes on P6 200MHz, old 5 to 7 us, new 4 to 6 us) |
| 168 | * (24 bytes on P6 200MHz, old 9 to 10 us, new 7 to 8 us) |
| 169 | * (for reference, 115200 b/s is 1 byte every 69 us) |
| 170 | * And reduce wrapper.o by ~900B in the process ;-) |
| 171 | * |
| 172 | * Then, we have the addition of ZeroCopy, which is optional |
| 173 | * (i.e. the driver must initiate it) and improve final processing. |
| 174 | * (2005 B frame + EOF on P6 200MHz, without 30 to 50 us, with 10 to 25 us) |
| 175 | * |
| 176 | * Note : at FIR and MIR, HDLC framing is used and usually handled |
| 177 | * by the controller, so we come here only for SIR... Jean II |
| 178 | */ |
| 179 | |
| 180 | /* |
| 181 | * We can also choose where we want to do the CRC calculation. We can |
| 182 | * do it "inline", as we receive the bytes, or "postponed", when |
| 183 | * receiving the End-Of-Frame. |
| 184 | * (16 bytes on P6 200MHz, inlined 4 to 6 us, postponed 4 to 5 us) |
| 185 | * (24 bytes on P6 200MHz, inlined 7 to 8 us, postponed 5 to 7 us) |
| 186 | * With ZeroCopy : |
| 187 | * (2005 B frame on P6 200MHz, inlined 10 to 25 us, postponed 140 to 180 us) |
| 188 | * Without ZeroCopy : |
| 189 | * (2005 B frame on P6 200MHz, inlined 30 to 50 us, postponed 150 to 180 us) |
| 190 | * (Note : numbers taken with irq disabled) |
| 191 | * |
| 192 | * From those numbers, it's not clear which is the best strategy, because |
| 193 | * we end up running through a lot of data one way or another (i.e. cache |
| 194 | * misses). I personally prefer to avoid the huge latency spike of the |
| 195 | * "postponed" solution, because it come just at the time when we have |
| 196 | * lot's of protocol processing to do and it will hurt our ability to |
| 197 | * reach low link turnaround times... Jean II |
| 198 | */ |
| 199 | //#define POSTPONE_RX_CRC |
| 200 | |
| 201 | /* |
| 202 | * Function async_bump (buf, len, stats) |
| 203 | * |
| 204 | * Got a frame, make a copy of it, and pass it up the stack! We can try |
| 205 | * to inline it since it's only called from state_inside_frame |
| 206 | */ |
| 207 | static inline void |
| 208 | async_bump(struct net_device *dev, |
| 209 | struct net_device_stats *stats, |
| 210 | iobuff_t *rx_buff) |
| 211 | { |
| 212 | struct sk_buff *newskb; |
| 213 | struct sk_buff *dataskb; |
| 214 | int docopy; |
| 215 | |
| 216 | /* Check if we need to copy the data to a new skb or not. |
| 217 | * If the driver doesn't use ZeroCopy Rx, we have to do it. |
| 218 | * With ZeroCopy Rx, the rx_buff already point to a valid |
| 219 | * skb. But, if the frame is small, it is more efficient to |
| 220 | * copy it to save memory (copy will be fast anyway - that's |
| 221 | * called Rx-copy-break). Jean II */ |
| 222 | docopy = ((rx_buff->skb == NULL) || |
| 223 | (rx_buff->len < IRDA_RX_COPY_THRESHOLD)); |
| 224 | |
| 225 | /* Allocate a new skb */ |
| 226 | newskb = dev_alloc_skb(docopy ? rx_buff->len + 1 : rx_buff->truesize); |
| 227 | if (!newskb) { |
| 228 | stats->rx_dropped++; |
| 229 | /* We could deliver the current skb if doing ZeroCopy Rx, |
| 230 | * but this would stall the Rx path. Better drop the |
| 231 | * packet... Jean II */ |
| 232 | return; |
| 233 | } |
| 234 | |
| 235 | /* Align IP header to 20 bytes (i.e. increase skb->data) |
| 236 | * Note this is only useful with IrLAN, as PPP has a variable |
| 237 | * header size (2 or 1 bytes) - Jean II */ |
| 238 | skb_reserve(newskb, 1); |
| 239 | |
| 240 | if(docopy) { |
| 241 | /* Copy data without CRC (lenght already checked) */ |
| 242 | memcpy(newskb->data, rx_buff->data, rx_buff->len - 2); |
| 243 | /* Deliver this skb */ |
| 244 | dataskb = newskb; |
| 245 | } else { |
| 246 | /* We are using ZeroCopy. Deliver old skb */ |
| 247 | dataskb = rx_buff->skb; |
| 248 | /* And hook the new skb to the rx_buff */ |
| 249 | rx_buff->skb = newskb; |
| 250 | rx_buff->head = newskb->data; /* NOT newskb->head */ |
| 251 | //printk(KERN_DEBUG "ZeroCopy : len = %d, dataskb = %p, newskb = %p\n", rx_buff->len, dataskb, newskb); |
| 252 | } |
| 253 | |
| 254 | /* Set proper length on skb (without CRC) */ |
| 255 | skb_put(dataskb, rx_buff->len - 2); |
| 256 | |
| 257 | /* Feed it to IrLAP layer */ |
| 258 | dataskb->dev = dev; |
Arnaldo Carvalho de Melo | 459a98e | 2007-03-19 15:30:44 -0700 | [diff] [blame^] | 259 | skb_reset_mac_header(dataskb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 260 | dataskb->protocol = htons(ETH_P_IRDA); |
| 261 | |
| 262 | netif_rx(dataskb); |
| 263 | |
| 264 | stats->rx_packets++; |
| 265 | stats->rx_bytes += rx_buff->len; |
| 266 | |
| 267 | /* Clean up rx_buff (redundant with async_unwrap_bof() ???) */ |
| 268 | rx_buff->data = rx_buff->head; |
| 269 | rx_buff->len = 0; |
| 270 | } |
| 271 | |
| 272 | /* |
| 273 | * Function async_unwrap_bof(dev, byte) |
| 274 | * |
| 275 | * Handle Beginning Of Frame character received within a frame |
| 276 | * |
| 277 | */ |
| 278 | static inline void |
| 279 | async_unwrap_bof(struct net_device *dev, |
| 280 | struct net_device_stats *stats, |
| 281 | iobuff_t *rx_buff, __u8 byte) |
| 282 | { |
| 283 | switch(rx_buff->state) { |
| 284 | case LINK_ESCAPE: |
| 285 | case INSIDE_FRAME: |
| 286 | /* Not supposed to happen, the previous frame is not |
| 287 | * finished - Jean II */ |
| 288 | IRDA_DEBUG(1, "%s(), Discarding incomplete frame\n", |
| 289 | __FUNCTION__); |
| 290 | stats->rx_errors++; |
| 291 | stats->rx_missed_errors++; |
| 292 | irda_device_set_media_busy(dev, TRUE); |
| 293 | break; |
| 294 | |
| 295 | case OUTSIDE_FRAME: |
| 296 | case BEGIN_FRAME: |
| 297 | default: |
YOSHIFUJI Hideaki | 6819bc2 | 2007-02-09 23:24:53 +0900 | [diff] [blame] | 298 | /* We may receive multiple BOF at the start of frame */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 299 | break; |
| 300 | } |
| 301 | |
| 302 | /* Now receiving frame */ |
| 303 | rx_buff->state = BEGIN_FRAME; |
| 304 | rx_buff->in_frame = TRUE; |
| 305 | |
| 306 | /* Time to initialize receive buffer */ |
| 307 | rx_buff->data = rx_buff->head; |
| 308 | rx_buff->len = 0; |
| 309 | rx_buff->fcs = INIT_FCS; |
| 310 | } |
| 311 | |
| 312 | /* |
| 313 | * Function async_unwrap_eof(dev, byte) |
| 314 | * |
| 315 | * Handle End Of Frame character received within a frame |
| 316 | * |
| 317 | */ |
| 318 | static inline void |
| 319 | async_unwrap_eof(struct net_device *dev, |
| 320 | struct net_device_stats *stats, |
| 321 | iobuff_t *rx_buff, __u8 byte) |
| 322 | { |
| 323 | #ifdef POSTPONE_RX_CRC |
| 324 | int i; |
| 325 | #endif |
| 326 | |
| 327 | switch(rx_buff->state) { |
| 328 | case OUTSIDE_FRAME: |
| 329 | /* Probably missed the BOF */ |
| 330 | stats->rx_errors++; |
| 331 | stats->rx_missed_errors++; |
| 332 | irda_device_set_media_busy(dev, TRUE); |
| 333 | break; |
| 334 | |
| 335 | case BEGIN_FRAME: |
| 336 | case LINK_ESCAPE: |
| 337 | case INSIDE_FRAME: |
| 338 | default: |
| 339 | /* Note : in the case of BEGIN_FRAME and LINK_ESCAPE, |
| 340 | * the fcs will most likely not match and generate an |
| 341 | * error, as expected - Jean II */ |
| 342 | rx_buff->state = OUTSIDE_FRAME; |
| 343 | rx_buff->in_frame = FALSE; |
| 344 | |
| 345 | #ifdef POSTPONE_RX_CRC |
| 346 | /* If we haven't done the CRC as we receive bytes, we |
| 347 | * must do it now... Jean II */ |
| 348 | for(i = 0; i < rx_buff->len; i++) |
| 349 | rx_buff->fcs = irda_fcs(rx_buff->fcs, |
| 350 | rx_buff->data[i]); |
| 351 | #endif |
| 352 | |
| 353 | /* Test FCS and signal success if the frame is good */ |
| 354 | if (rx_buff->fcs == GOOD_FCS) { |
| 355 | /* Deliver frame */ |
| 356 | async_bump(dev, stats, rx_buff); |
| 357 | break; |
| 358 | } else { |
| 359 | /* Wrong CRC, discard frame! */ |
| 360 | irda_device_set_media_busy(dev, TRUE); |
| 361 | |
| 362 | IRDA_DEBUG(1, "%s(), crc error\n", __FUNCTION__); |
| 363 | stats->rx_errors++; |
| 364 | stats->rx_crc_errors++; |
| 365 | } |
| 366 | break; |
| 367 | } |
| 368 | } |
| 369 | |
| 370 | /* |
| 371 | * Function async_unwrap_ce(dev, byte) |
| 372 | * |
| 373 | * Handle Character Escape character received within a frame |
| 374 | * |
| 375 | */ |
| 376 | static inline void |
| 377 | async_unwrap_ce(struct net_device *dev, |
| 378 | struct net_device_stats *stats, |
| 379 | iobuff_t *rx_buff, __u8 byte) |
| 380 | { |
| 381 | switch(rx_buff->state) { |
| 382 | case OUTSIDE_FRAME: |
| 383 | /* Activate carrier sense */ |
| 384 | irda_device_set_media_busy(dev, TRUE); |
| 385 | break; |
| 386 | |
| 387 | case LINK_ESCAPE: |
| 388 | IRDA_WARNING("%s: state not defined\n", __FUNCTION__); |
| 389 | break; |
| 390 | |
| 391 | case BEGIN_FRAME: |
| 392 | case INSIDE_FRAME: |
| 393 | default: |
| 394 | /* Stuffed byte coming */ |
| 395 | rx_buff->state = LINK_ESCAPE; |
| 396 | break; |
| 397 | } |
| 398 | } |
| 399 | |
| 400 | /* |
| 401 | * Function async_unwrap_other(dev, byte) |
| 402 | * |
| 403 | * Handle other characters received within a frame |
| 404 | * |
| 405 | */ |
| 406 | static inline void |
| 407 | async_unwrap_other(struct net_device *dev, |
| 408 | struct net_device_stats *stats, |
| 409 | iobuff_t *rx_buff, __u8 byte) |
| 410 | { |
| 411 | switch(rx_buff->state) { |
| 412 | /* This is on the critical path, case are ordered by |
| 413 | * probability (most frequent first) - Jean II */ |
| 414 | case INSIDE_FRAME: |
| 415 | /* Must be the next byte of the frame */ |
| 416 | if (rx_buff->len < rx_buff->truesize) { |
| 417 | rx_buff->data[rx_buff->len++] = byte; |
| 418 | #ifndef POSTPONE_RX_CRC |
| 419 | rx_buff->fcs = irda_fcs(rx_buff->fcs, byte); |
| 420 | #endif |
| 421 | } else { |
| 422 | IRDA_DEBUG(1, "%s(), Rx buffer overflow, aborting\n", |
| 423 | __FUNCTION__); |
| 424 | rx_buff->state = OUTSIDE_FRAME; |
| 425 | } |
| 426 | break; |
| 427 | |
| 428 | case LINK_ESCAPE: |
| 429 | /* |
| 430 | * Stuffed char, complement bit 5 of byte |
| 431 | * following CE, IrLAP p.114 |
| 432 | */ |
| 433 | byte ^= IRDA_TRANS; |
| 434 | if (rx_buff->len < rx_buff->truesize) { |
| 435 | rx_buff->data[rx_buff->len++] = byte; |
| 436 | #ifndef POSTPONE_RX_CRC |
| 437 | rx_buff->fcs = irda_fcs(rx_buff->fcs, byte); |
| 438 | #endif |
| 439 | rx_buff->state = INSIDE_FRAME; |
| 440 | } else { |
| 441 | IRDA_DEBUG(1, "%s(), Rx buffer overflow, aborting\n", |
| 442 | __FUNCTION__); |
| 443 | rx_buff->state = OUTSIDE_FRAME; |
| 444 | } |
| 445 | break; |
| 446 | |
| 447 | case OUTSIDE_FRAME: |
| 448 | /* Activate carrier sense */ |
| 449 | if(byte != XBOF) |
| 450 | irda_device_set_media_busy(dev, TRUE); |
| 451 | break; |
| 452 | |
| 453 | case BEGIN_FRAME: |
| 454 | default: |
| 455 | rx_buff->data[rx_buff->len++] = byte; |
| 456 | #ifndef POSTPONE_RX_CRC |
| 457 | rx_buff->fcs = irda_fcs(rx_buff->fcs, byte); |
| 458 | #endif |
| 459 | rx_buff->state = INSIDE_FRAME; |
| 460 | break; |
| 461 | } |
| 462 | } |
| 463 | |
| 464 | /* |
| 465 | * Function async_unwrap_char (dev, rx_buff, byte) |
| 466 | * |
| 467 | * Parse and de-stuff frame received from the IrDA-port |
| 468 | * |
| 469 | * This is the main entry point for SIR drivers. |
| 470 | */ |
| 471 | void async_unwrap_char(struct net_device *dev, |
| 472 | struct net_device_stats *stats, |
| 473 | iobuff_t *rx_buff, __u8 byte) |
| 474 | { |
| 475 | switch(byte) { |
| 476 | case CE: |
| 477 | async_unwrap_ce(dev, stats, rx_buff, byte); |
| 478 | break; |
| 479 | case BOF: |
| 480 | async_unwrap_bof(dev, stats, rx_buff, byte); |
| 481 | break; |
| 482 | case EOF: |
| 483 | async_unwrap_eof(dev, stats, rx_buff, byte); |
| 484 | break; |
| 485 | default: |
| 486 | async_unwrap_other(dev, stats, rx_buff, byte); |
| 487 | break; |
| 488 | } |
| 489 | } |
| 490 | EXPORT_SYMBOL(async_unwrap_char); |
| 491 | |