drivers/isdn/gigaset/asyncdata.c

   1 /*
   2  * Common data handling layer for ser_gigaset and usb_gigaset
   3  *
   4  * Copyright (c) 2005 by Tilman Schmidt <tilman@imap.cc>,
   5  *                       Hansjoerg Lipp <hjlipp@web.de>,
   6  *                       Stefan Eilers <Eilers.Stefan@epost.de>.
   7  *
   8  * =====================================================================
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License as
  11  *      published by the Free Software Foundation; either version 2 of
  12  *      the License, or (at your option) any later version.
  13  * =====================================================================
  14  */
  15
  16 #include "gigaset.h"
  17 #include <linux/crc-ccitt.h>
  18
  19 //#define GIG_M10x_STUFF_VOICE_DATA
  20
  21 /* check if byte must be stuffed/escaped
  22  * I'm not sure which data should be encoded.
  23  * Therefore I will go the hard way and decode every value
  24  * less than 0x20, the flag sequence and the control escape char.
  25  */
  26 static inline int muststuff(unsigned char c)
  27 {
  28         if (c < PPP_TRANS) return 1;
  29         if (c == PPP_FLAG) return 1;
  30         if (c == PPP_ESCAPE) return 1;
  31         /* other possible candidates: */
  32         /* 0x91: XON with parity set */
  33         /* 0x93: XOFF with parity set */
  34         return 0;
  35 }
  36
  37 /* == data input =========================================================== */
  38
  39 /* process a block of received bytes in command mode (modem response)
  40  * Return value:
  41  *      number of processed bytes
  42  */
  43 static inline int cmd_loop(unsigned char c, unsigned char *src, int numbytes,
  44                            struct inbuf_t *inbuf)
  45 {
  46         struct cardstate *cs = inbuf->cs;
  47         unsigned cbytes      = cs->cbytes;
  48         int inputstate = inbuf->inputstate;
  49         int startbytes = numbytes;
  50
  51         for (;;) {
  52                 cs->respdata[cbytes] = c;
  53                 if (c == 10 || c == 13) {
  54                         dbg(DEBUG_TRANSCMD, "%s: End of Command (%d Bytes)",
  55                             __func__, cbytes);
  56                         cs->cbytes = cbytes;
  57                         gigaset_handle_modem_response(cs); /* can change
  58                                                               cs->dle */
  59                         cbytes = 0;
  60
  61                         if (cs->dle &&
  62                             !(inputstate & INS_DLE_command)) {
  63                                 inputstate &= ~INS_command;
  64                                 break;
  65                         }
  66                 } else {
  67                         /* advance in line buffer, checking for overflow */
  68                         if (cbytes < MAX_RESP_SIZE - 1)
  69                                 cbytes++;
  70                         else
  71                                 warn("response too large");
  72                 }
  73
  74                 if (!numbytes)
  75                         break;
  76                 c = *src++;
  77                 --numbytes;
  78                 if (c == DLE_FLAG &&
  79                     (cs->dle || inputstate & INS_DLE_command)) {
  80                         inputstate |= INS_DLE_char;
  81                         break;
  82                 }
  83         }
  84
  85         cs->cbytes = cbytes;
  86         inbuf->inputstate = inputstate;
  87
  88         return startbytes - numbytes;
  89 }
  90
  91 /* process a block of received bytes in lock mode (tty i/f)
  92  * Return value:
  93  *      number of processed bytes
  94  */
  95 static inline int lock_loop(unsigned char *src, int numbytes,
  96                             struct inbuf_t *inbuf)
  97 {
  98         struct cardstate *cs = inbuf->cs;
  99
 100         gigaset_dbg_buffer(DEBUG_LOCKCMD, "received response",
 101                            numbytes, src, 0);
 102         gigaset_if_receive(cs, src, numbytes);
 103
 104         return numbytes;
 105 }
 106
 107 /* process a block of received bytes in HDLC data mode
 108  * Collect HDLC frames, undoing byte stuffing and watching for DLE escapes.
 109  * When a frame is complete, check the FCS and pass valid frames to the LL.
 110  * If DLE is encountered, return immediately to let the caller handle it.
 111  * Return value:
 112  *      number of processed bytes
 113  *      numbytes (all bytes processed) on error --FIXME
 114  */
 115 static inline int hdlc_loop(unsigned char c, unsigned char *src, int numbytes,
 116                             struct inbuf_t *inbuf)
 117 {
 118         struct cardstate *cs = inbuf->cs;
 119         struct bc_state *bcs = inbuf->bcs;
 120         int inputstate;
 121         __u16 fcs;
 122         struct sk_buff *skb;
 123         unsigned char error;
 124         struct sk_buff *compskb;
 125         int startbytes = numbytes;
 126         int l;
 127
 128         IFNULLRETVAL(bcs, numbytes);
 129         inputstate = bcs->inputstate;
 130         fcs = bcs->fcs;
 131         skb = bcs->skb;
 132         IFNULLRETVAL(skb, numbytes);
 133
 134         if (unlikely(inputstate & INS_byte_stuff)) {
 135                 inputstate &= ~INS_byte_stuff;
 136                 goto byte_stuff;
 137         }
 138         for (;;) {
 139                 if (unlikely(c == PPP_ESCAPE)) {
 140                         if (unlikely(!numbytes)) {
 141                                 inputstate |= INS_byte_stuff;
 142                                 break;
 143                         }
 144                         c = *src++;
 145                         --numbytes;
 146                         if (unlikely(c == DLE_FLAG &&
 147                                      (cs->dle ||
 148                                       inbuf->inputstate & INS_DLE_command))) {
 149                                 inbuf->inputstate |= INS_DLE_char;
 150                                 inputstate |= INS_byte_stuff;
 151                                 break;
 152                         }
 153 byte_stuff:
 154                         c ^= PPP_TRANS;
 155 #ifdef CONFIG_GIGASET_DEBUG
 156                         if (unlikely(!muststuff(c)))
 157                                 dbg(DEBUG_HDLC,
 158                                     "byte stuffed: 0x%02x", c);
 159 #endif
 160                 } else if (unlikely(c == PPP_FLAG)) {
 161                         if (unlikely(inputstate & INS_skip_frame)) {
 162                                 if (!(inputstate & INS_have_data)) { /* 7E 7E */
 163                                         //dbg(DEBUG_HDLC, "(7e)7e------------------------");
 164 #ifdef CONFIG_GIGASET_DEBUG
 165                                         ++bcs->emptycount;
 166 #endif
 167                                 } else
 168                                         dbg(DEBUG_HDLC,
 169                                             "7e----------------------------");
 170
 171                                 /* end of frame */
 172                                 error = 1;
 173                                 gigaset_rcv_error(NULL, cs, bcs);
 174                         } else if (!(inputstate & INS_have_data)) { /* 7E 7E */
 175                                 //dbg(DEBUG_HDLC, "(7e)7e------------------------");
 176 #ifdef CONFIG_GIGASET_DEBUG
 177                                 ++bcs->emptycount;
 178 #endif
 179                                 break;
 180                         } else {
 181                                 dbg(DEBUG_HDLC,
 182                                     "7e----------------------------");
 183
 184                                 /* end of frame */
 185                                 error = 0;
 186
 187                                 if (unlikely(fcs != PPP_GOODFCS)) {
 188                                         err("Packet checksum at %lu failed, "
 189                                             "packet is corrupted (%u bytes)!",
 190                                             bcs->rcvbytes, skb->len);
 191                                         compskb = NULL;
 192                                         gigaset_rcv_error(compskb, cs, bcs);
 193                                         error = 1;
 194                                 } else {
 195                                         if (likely((l = skb->len) > 2)) {
 196                                                 skb->tail -= 2;
 197                                                 skb->len -= 2;
 198                                         } else {
 199                                                 dev_kfree_skb(skb);
 200                                                 skb = NULL;
 201                                                 inputstate |= INS_skip_frame;
 202                                                 if (l == 1) {
 203                                                         err("invalid packet size (1)!");
 204                                                         error = 1;
 205                                                         gigaset_rcv_error(NULL, cs, bcs);
 206                                                 }
 207                                         }
 208                                         if (likely(!(error ||
 209                                                      (inputstate &
 210                                                       INS_skip_frame)))) {
 211                                                 gigaset_rcv_skb(skb, cs, bcs);
 212                                         }
 213                                 }
 214                         }
 215
 216                         if (unlikely(error))
 217                                 if (skb)
 218                                         dev_kfree_skb(skb);
 219
 220                         fcs = PPP_INITFCS;
 221                         inputstate &= ~(INS_have_data | INS_skip_frame);
 222                         if (unlikely(bcs->ignore)) {
 223                                 inputstate |= INS_skip_frame;
 224                                 skb = NULL;
 225                         } else if (likely((skb = dev_alloc_skb(SBUFSIZE + HW_HDR_LEN)) != NULL)) {
 226                                 skb_reserve(skb, HW_HDR_LEN);
 227                         } else {
 228                                 warn("could not allocate new skb");
 229                                 inputstate |= INS_skip_frame;
 230                         }
 231
 232                         break;
 233 #ifdef CONFIG_GIGASET_DEBUG
 234                 } else if (unlikely(muststuff(c))) {
 235                         /* Should not happen. Possible after ZDLE=1<CR><LF>. */
 236                         dbg(DEBUG_HDLC, "not byte stuffed: 0x%02x", c);
 237 #endif
 238                 }
 239
 240                 /* add character */
 241
 242 #ifdef CONFIG_GIGASET_DEBUG
 243                 if (unlikely(!(inputstate & INS_have_data))) {
 244                         dbg(DEBUG_HDLC,
 245                             "7e (%d x) ================", bcs->emptycount);
 246                         bcs->emptycount = 0;
 247                 }
 248 #endif
 249
 250                 inputstate |= INS_have_data;
 251
 252                 if (likely(!(inputstate & INS_skip_frame))) {
 253                         if (unlikely(skb->len == SBUFSIZE)) {
 254                                 warn("received packet too long");
 255                                 dev_kfree_skb_any(skb);
 256                                 skb = NULL;
 257                                 inputstate |= INS_skip_frame;
 258                                 break;
 259                         }
 260                         *gigaset_skb_put_quick(skb, 1) = c;
 261                         /* *__skb_put (skb, 1) = c; */
 262                         fcs = crc_ccitt_byte(fcs, c);
 263                 }
 264
 265                 if (unlikely(!numbytes))
 266                         break;
 267                 c = *src++;
 268                 --numbytes;
 269                 if (unlikely(c == DLE_FLAG &&
 270                              (cs->dle ||
 271                               inbuf->inputstate & INS_DLE_command))) {
 272                         inbuf->inputstate |= INS_DLE_char;
 273                         break;
 274                 }
 275         }
 276         bcs->inputstate = inputstate;
 277         bcs->fcs = fcs;
 278         bcs->skb = skb;
 279         return startbytes - numbytes;
 280 }
 281
 282 /* process a block of received bytes in transparent data mode
 283  * Invert bytes, undoing byte stuffing and watching for DLE escapes.
 284  * If DLE is encountered, return immediately to let the caller handle it.
 285  * Return value:
 286  *      number of processed bytes
 287  *      numbytes (all bytes processed) on error --FIXME
 288  */
 289 static inline int iraw_loop(unsigned char c, unsigned char *src, int numbytes,
 290                             struct inbuf_t *inbuf)
 291 {
 292         struct cardstate *cs = inbuf->cs;
 293         struct bc_state *bcs = inbuf->bcs;
 294         int inputstate;
 295         struct sk_buff *skb;
 296         int startbytes = numbytes;
 297
 298         IFNULLRETVAL(bcs, numbytes);
 299         inputstate = bcs->inputstate;
 300         skb = bcs->skb;
 301         IFNULLRETVAL(skb, numbytes);
 302
 303         for (;;) {
 304                 /* add character */
 305                 inputstate |= INS_have_data;
 306
 307                 if (likely(!(inputstate & INS_skip_frame))) {
 308                         if (unlikely(skb->len == SBUFSIZE)) {
 309                                 //FIXME just pass skb up and allocate a new one
 310                                 warn("received packet too long");
 311                                 dev_kfree_skb_any(skb);
 312                                 skb = NULL;
 313                                 inputstate |= INS_skip_frame;
 314                                 break;
 315                         }
 316                         *gigaset_skb_put_quick(skb, 1) = gigaset_invtab[c];
 317                 }
 318
 319                 if (unlikely(!numbytes))
 320                         break;
 321                 c = *src++;
 322                 --numbytes;
 323                 if (unlikely(c == DLE_FLAG &&
 324                              (cs->dle ||
 325                               inbuf->inputstate & INS_DLE_command))) {
 326                         inbuf->inputstate |= INS_DLE_char;
 327                         break;
 328                 }
 329         }
 330
 331         /* pass data up */
 332         if (likely(inputstate & INS_have_data)) {
 333                 if (likely(!(inputstate & INS_skip_frame))) {
 334                         gigaset_rcv_skb(skb, cs, bcs);
 335                 }
 336                 inputstate &= ~(INS_have_data | INS_skip_frame);
 337                 if (unlikely(bcs->ignore)) {
 338                         inputstate |= INS_skip_frame;
 339                         skb = NULL;
 340                 } else if (likely((skb = dev_alloc_skb(SBUFSIZE + HW_HDR_LEN))
 341                                   != NULL)) {
 342                         skb_reserve(skb, HW_HDR_LEN);
 343                 } else {
 344                         warn("could not allocate new skb");
 345                         inputstate |= INS_skip_frame;
 346                 }
 347         }
 348
 349         bcs->inputstate = inputstate;
 350         bcs->skb = skb;
 351         return startbytes - numbytes;
 352 }
 353
 354 /* process a block of data received from the device
 355  */
 356 void gigaset_m10x_input(struct inbuf_t *inbuf)
 357 {
 358         struct cardstate *cs;
 359         unsigned tail, head, numbytes;
 360         unsigned char *src, c;
 361         int procbytes;
 362
 363         head = atomic_read(&inbuf->head);
 364         tail = atomic_read(&inbuf->tail);
 365         dbg(DEBUG_INTR, "buffer state: %u -> %u", head, tail);
 366
 367         if (head != tail) {
 368                 cs = inbuf->cs;
 369                 src = inbuf->data + head;
 370                 numbytes = (head > tail ? RBUFSIZE : tail) - head;
 371                 dbg(DEBUG_INTR, "processing %u bytes", numbytes);
 372
 373                 while (numbytes) {
 374                         if (atomic_read(&cs->mstate) == MS_LOCKED) {
 375                                 procbytes = lock_loop(src, numbytes, inbuf);
 376                                 src += procbytes;
 377                                 numbytes -= procbytes;
 378                         } else {
 379                                 c = *src++;
 380                                 --numbytes;
 381                                 if (c == DLE_FLAG && (cs->dle ||
 382                                     inbuf->inputstate & INS_DLE_command)) {
 383                                         if (!(inbuf->inputstate & INS_DLE_char)) {
 384                                                 inbuf->inputstate |= INS_DLE_char;
 385                                                 goto nextbyte;
 386                                         }
 387                                         /* <DLE> <DLE> => <DLE> in data stream */
 388                                         inbuf->inputstate &= ~INS_DLE_char;
 389                                 }
 390
 391                                 if (!(inbuf->inputstate & INS_DLE_char)) {
 392
 393                                         /* FIXME use function pointers?  */
 394                                         if (inbuf->inputstate & INS_command)
 395                                                 procbytes = cmd_loop(c, src, numbytes, inbuf);
 396                                         else if (inbuf->bcs->proto2 == ISDN_PROTO_L2_HDLC)
 397                                                 procbytes = hdlc_loop(c, src, numbytes, inbuf);
 398                                         else
 399                                                 procbytes = iraw_loop(c, src, numbytes, inbuf);
 400
 401                                         src += procbytes;
 402                                         numbytes -= procbytes;
 403                                 } else {  /* DLE-char */
 404                                         inbuf->inputstate &= ~INS_DLE_char;
 405                                         switch (c) {
 406                                         case 'X': /*begin of command*/
 407 #ifdef CONFIG_GIGASET_DEBUG
 408                                                 if (inbuf->inputstate & INS_command)
 409                                                         err("received <DLE> 'X' in command mode");
 410 #endif
 411                                                 inbuf->inputstate |=
 412                                                         INS_command | INS_DLE_command;
 413                                                 break;
 414                                         case '.': /*end of command*/
 415 #ifdef CONFIG_GIGASET_DEBUG
 416                                                 if (!(inbuf->inputstate & INS_command))
 417                                                         err("received <DLE> '.' in hdlc mode");
 418 #endif
 419                                                 inbuf->inputstate &= cs->dle ?
 420                                                         ~(INS_DLE_command|INS_command)
 421                                                         : ~INS_DLE_command;
 422                                                 break;
 423                                         //case DLE_FLAG: /*DLE_FLAG in data stream*/ /* schon oben behandelt! */
 424                                         default:
 425                                                 err("received 0x10 0x%02x!", (int) c);
 426                                                 /* FIXME: reset driver?? */
 427                                         }
 428                                 }
 429                         }
 430 nextbyte:
 431                         if (!numbytes) {
 432                                 /* end of buffer, check for wrap */
 433                                 if (head > tail) {
 434                                         head = 0;
 435                                         src = inbuf->data;
 436                                         numbytes = tail;
 437                                 } else {
 438                                         head = tail;
 439                                         break;
 440                                 }
 441                         }
 442                 }
 443
 444                 dbg(DEBUG_INTR, "setting head to %u", head);
 445                 atomic_set(&inbuf->head, head);
 446         }
 447 }
 448
 449
 450 /* == data output ========================================================== */
 451
 452 /* Encoding of a PPP packet into an octet stuffed HDLC frame
 453  * with FCS, opening and closing flags.
 454  * parameters:
 455  *      skb     skb containing original packet (freed upon return)
 456  *      head    number of headroom bytes to allocate in result skb
 457  *      tail    number of tailroom bytes to allocate in result skb
 458  * Return value:
 459  *      pointer to newly allocated skb containing the result frame
 460  */
 461 static struct sk_buff *HDLC_Encode(struct sk_buff *skb, int head, int tail)
 462 {
 463         struct sk_buff *hdlc_skb;
 464         __u16 fcs;
 465         unsigned char c;
 466         unsigned char *cp;
 467         int len;
 468         unsigned int stuf_cnt;
 469
 470         stuf_cnt = 0;
 471         fcs = PPP_INITFCS;
 472         cp = skb->data;
 473         len = skb->len;
 474         while (len--) {
 475                 if (muststuff(*cp))
 476                         stuf_cnt++;
 477                 fcs = crc_ccitt_byte(fcs, *cp++);
 478         }
 479         fcs ^= 0xffff;                 /* complement */
 480
 481         /* size of new buffer: original size + number of stuffing bytes
 482          * + 2 bytes FCS + 2 stuffing bytes for FCS (if needed) + 2 flag bytes
 483          */
 484         hdlc_skb = dev_alloc_skb(skb->len + stuf_cnt + 6 + tail + head);
 485         if (!hdlc_skb) {
 486                 err("unable to allocate memory for HDLC encoding!");
 487                 dev_kfree_skb(skb);
 488                 return NULL;
 489         }
 490         skb_reserve(hdlc_skb, head);
 491
 492         /* Copy acknowledge request into new skb */
 493         memcpy(hdlc_skb->head, skb->head, 2);
 494
 495         /* Add flag sequence in front of everything.. */
 496         *(skb_put(hdlc_skb, 1)) = PPP_FLAG;
 497
 498         /* Perform byte stuffing while copying data. */
 499         while (skb->len--) {
 500                 if (muststuff(*skb->data)) {
 501                         *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
 502                         *(skb_put(hdlc_skb, 1)) = (*skb->data++) ^ PPP_TRANS;
 503                 } else
 504                         *(skb_put(hdlc_skb, 1)) = *skb->data++;
 505         }
 506
 507         /* Finally add FCS (byte stuffed) and flag sequence */
 508         c = (fcs & 0x00ff);      /* least significant byte first */
 509         if (muststuff(c)) {
 510                 *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
 511                 c ^= PPP_TRANS;
 512         }
 513         *(skb_put(hdlc_skb, 1)) = c;
 514
 515         c = ((fcs >> 8) & 0x00ff);
 516         if (muststuff(c)) {
 517                 *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
 518                 c ^= PPP_TRANS;
 519         }
 520         *(skb_put(hdlc_skb, 1)) = c;
 521
 522         *(skb_put(hdlc_skb, 1)) = PPP_FLAG;
 523
 524         dev_kfree_skb(skb);
 525         return hdlc_skb;
 526 }
 527
 528 /* Encoding of a raw packet into an octet stuffed bit inverted frame
 529  * parameters:
 530  *      skb     skb containing original packet (freed upon return)
 531  *      head    number of headroom bytes to allocate in result skb
 532  *      tail    number of tailroom bytes to allocate in result skb
 533  * Return value:
 534  *      pointer to newly allocated skb containing the result frame
 535  */
 536 static struct sk_buff *iraw_encode(struct sk_buff *skb, int head, int tail)
 537 {
 538         struct sk_buff *iraw_skb;
 539         unsigned char c;
 540         unsigned char *cp;
 541         int len;
 542
 543         /* worst case: every byte must be stuffed */
 544         iraw_skb = dev_alloc_skb(2*skb->len + tail + head);
 545         if (!iraw_skb) {
 546                 err("unable to allocate memory for HDLC encoding!");
 547                 dev_kfree_skb(skb);
 548                 return NULL;
 549         }
 550         skb_reserve(iraw_skb, head);
 551
 552         cp = skb->data;
 553         len = skb->len;
 554         while (len--) {
 555                 c = gigaset_invtab[*cp++];
 556                 if (c == DLE_FLAG)
 557                         *(skb_put(iraw_skb, 1)) = c;
 558                 *(skb_put(iraw_skb, 1)) = c;
 559         }
 560         dev_kfree_skb(skb);
 561         return iraw_skb;
 562 }
 563
 564 /* gigaset_send_skb
 565  * called by common.c to queue an skb for sending
 566  * and start transmission if necessary
 567  * parameters:
 568  *      B Channel control structure
 569  *      skb
 570  * Return value:
 571  *      number of bytes accepted for sending
 572  *      (skb->len if ok, 0 if out of buffer space)
 573  *      or error code (< 0, eg. -EINVAL)
 574  */
 575 int gigaset_m10x_send_skb(struct bc_state *bcs, struct sk_buff *skb)
 576 {
 577         unsigned len;
 578
 579         IFNULLRETVAL(bcs, -EFAULT);
 580         IFNULLRETVAL(skb, -EFAULT);
 581         len = skb->len;
 582
 583         if (bcs->proto2 == ISDN_PROTO_L2_HDLC)
 584                 skb = HDLC_Encode(skb, HW_HDR_LEN, 0);
 585         else
 586                 skb = iraw_encode(skb, HW_HDR_LEN, 0);
 587         if (!skb)
 588                 return -ENOMEM;
 589
 590         skb_queue_tail(&bcs->squeue, skb);
 591         tasklet_schedule(&bcs->cs->write_tasklet);
 592
 593         return len;     /* ok so far */
 594 }