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.
   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                         gig_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                                 dev_warn(cs->dev, "response too large\n");
  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);
 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 = bcs->inputstate;
 121         __u16 fcs = bcs->fcs;
 122         struct sk_buff *skb = bcs->skb;
 123         unsigned char error;
 124         struct sk_buff *compskb;
 125         int startbytes = numbytes;
 126         int l;
 127
 128         if (unlikely(inputstate & INS_byte_stuff)) {
 129                 inputstate &= ~INS_byte_stuff;
 130                 goto byte_stuff;
 131         }
 132         for (;;) {
 133                 if (unlikely(c == PPP_ESCAPE)) {
 134                         if (unlikely(!numbytes)) {
 135                                 inputstate |= INS_byte_stuff;
 136                                 break;
 137                         }
 138                         c = *src++;
 139                         --numbytes;
 140                         if (unlikely(c == DLE_FLAG &&
 141                                      (cs->dle ||
 142                                       inbuf->inputstate & INS_DLE_command))) {
 143                                 inbuf->inputstate |= INS_DLE_char;
 144                                 inputstate |= INS_byte_stuff;
 145                                 break;
 146                         }
 147 byte_stuff:
 148                         c ^= PPP_TRANS;
 149 #ifdef CONFIG_GIGASET_DEBUG
 150                         if (unlikely(!muststuff(c)))
 151                                 gig_dbg(DEBUG_HDLC, "byte stuffed: 0x%02x", c);
 152 #endif
 153                 } else if (unlikely(c == PPP_FLAG)) {
 154                         if (unlikely(inputstate & INS_skip_frame)) {
 155                                 if (!(inputstate & INS_have_data)) { /* 7E 7E */
 156 #ifdef CONFIG_GIGASET_DEBUG
 157                                         ++bcs->emptycount;
 158 #endif
 159                                 } else
 160                                         gig_dbg(DEBUG_HDLC,
 161                                             "7e----------------------------");
 162
 163                                 /* end of frame */
 164                                 error = 1;
 165                                 gigaset_rcv_error(NULL, cs, bcs);
 166                         } else if (!(inputstate & INS_have_data)) { /* 7E 7E */
 167 #ifdef CONFIG_GIGASET_DEBUG
 168                                 ++bcs->emptycount;
 169 #endif
 170                                 break;
 171                         } else {
 172                                 gig_dbg(DEBUG_HDLC,
 173                                         "7e----------------------------");
 174
 175                                 /* end of frame */
 176                                 error = 0;
 177
 178                                 if (unlikely(fcs != PPP_GOODFCS)) {
 179                                         dev_err(cs->dev,
 180                                             "Packet checksum at %lu failed, "
 181                                             "packet is corrupted (%u bytes)!\n",
 182                                             bcs->rcvbytes, skb->len);
 183                                         compskb = NULL;
 184                                         gigaset_rcv_error(compskb, cs, bcs);
 185                                         error = 1;
 186                                 } else {
 187                                         if (likely((l = skb->len) > 2)) {
 188                                                 skb->tail -= 2;
 189                                                 skb->len -= 2;
 190                                         } else {
 191                                                 dev_kfree_skb(skb);
 192                                                 skb = NULL;
 193                                                 inputstate |= INS_skip_frame;
 194                                                 if (l == 1) {
 195                                                         dev_err(cs->dev,
 196                                                   "invalid packet size (1)!\n");
 197                                                         error = 1;
 198                                                         gigaset_rcv_error(NULL,
 199                                                                 cs, bcs);
 200                                                 }
 201                                         }
 202                                         if (likely(!(error ||
 203                                                      (inputstate &
 204                                                       INS_skip_frame)))) {
 205                                                 gigaset_rcv_skb(skb, cs, bcs);
 206                                         }
 207                                 }
 208                         }
 209
 210                         if (unlikely(error))
 211                                 if (skb)
 212                                         dev_kfree_skb(skb);
 213
 214                         fcs = PPP_INITFCS;
 215                         inputstate &= ~(INS_have_data | INS_skip_frame);
 216                         if (unlikely(bcs->ignore)) {
 217                                 inputstate |= INS_skip_frame;
 218                                 skb = NULL;
 219                         } else if (likely((skb = dev_alloc_skb(SBUFSIZE + HW_HDR_LEN)) != NULL)) {
 220                                 skb_reserve(skb, HW_HDR_LEN);
 221                         } else {
 222                                 dev_warn(cs->dev,
 223                                          "could not allocate new skb\n");
 224                                 inputstate |= INS_skip_frame;
 225                         }
 226
 227                         break;
 228 #ifdef CONFIG_GIGASET_DEBUG
 229                 } else if (unlikely(muststuff(c))) {
 230                         /* Should not happen. Possible after ZDLE=1<CR><LF>. */
 231                         gig_dbg(DEBUG_HDLC, "not byte stuffed: 0x%02x", c);
 232 #endif
 233                 }
 234
 235                 /* add character */
 236
 237 #ifdef CONFIG_GIGASET_DEBUG
 238                 if (unlikely(!(inputstate & INS_have_data))) {
 239                         gig_dbg(DEBUG_HDLC, "7e (%d x) ================",
 240                                 bcs->emptycount);
 241                         bcs->emptycount = 0;
 242                 }
 243 #endif
 244
 245                 inputstate |= INS_have_data;
 246
 247                 if (likely(!(inputstate & INS_skip_frame))) {
 248                         if (unlikely(skb->len == SBUFSIZE)) {
 249                                 dev_warn(cs->dev, "received packet too long\n");
 250                                 dev_kfree_skb_any(skb);
 251                                 skb = NULL;
 252                                 inputstate |= INS_skip_frame;
 253                                 break;
 254                         }
 255                         *__skb_put(skb, 1) = c;
 256                         fcs = crc_ccitt_byte(fcs, c);
 257                 }
 258
 259                 if (unlikely(!numbytes))
 260                         break;
 261                 c = *src++;
 262                 --numbytes;
 263                 if (unlikely(c == DLE_FLAG &&
 264                              (cs->dle ||
 265                               inbuf->inputstate & INS_DLE_command))) {
 266                         inbuf->inputstate |= INS_DLE_char;
 267                         break;
 268                 }
 269         }
 270         bcs->inputstate = inputstate;
 271         bcs->fcs = fcs;
 272         bcs->skb = skb;
 273         return startbytes - numbytes;
 274 }
 275
 276 /* process a block of received bytes in transparent data mode
 277  * Invert bytes, undoing byte stuffing and watching for DLE escapes.
 278  * If DLE is encountered, return immediately to let the caller handle it.
 279  * Return value:
 280  *      number of processed bytes
 281  *      numbytes (all bytes processed) on error --FIXME
 282  */
 283 static inline int iraw_loop(unsigned char c, unsigned char *src, int numbytes,
 284                             struct inbuf_t *inbuf)
 285 {
 286         struct cardstate *cs = inbuf->cs;
 287         struct bc_state *bcs = inbuf->bcs;
 288         int inputstate = bcs->inputstate;
 289         struct sk_buff *skb = bcs->skb;
 290         int startbytes = numbytes;
 291
 292         for (;;) {
 293                 /* add character */
 294                 inputstate |= INS_have_data;
 295
 296                 if (likely(!(inputstate & INS_skip_frame))) {
 297                         if (unlikely(skb->len == SBUFSIZE)) {
 298                                 //FIXME just pass skb up and allocate a new one
 299                                 dev_warn(cs->dev, "received packet too long\n");
 300                                 dev_kfree_skb_any(skb);
 301                                 skb = NULL;
 302                                 inputstate |= INS_skip_frame;
 303                                 break;
 304                         }
 305                         *__skb_put(skb, 1) = gigaset_invtab[c];
 306                 }
 307
 308                 if (unlikely(!numbytes))
 309                         break;
 310                 c = *src++;
 311                 --numbytes;
 312                 if (unlikely(c == DLE_FLAG &&
 313                              (cs->dle ||
 314                               inbuf->inputstate & INS_DLE_command))) {
 315                         inbuf->inputstate |= INS_DLE_char;
 316                         break;
 317                 }
 318         }
 319
 320         /* pass data up */
 321         if (likely(inputstate & INS_have_data)) {
 322                 if (likely(!(inputstate & INS_skip_frame))) {
 323                         gigaset_rcv_skb(skb, cs, bcs);
 324                 }
 325                 inputstate &= ~(INS_have_data | INS_skip_frame);
 326                 if (unlikely(bcs->ignore)) {
 327                         inputstate |= INS_skip_frame;
 328                         skb = NULL;
 329                 } else if (likely((skb = dev_alloc_skb(SBUFSIZE + HW_HDR_LEN))
 330                                   != NULL)) {
 331                         skb_reserve(skb, HW_HDR_LEN);
 332                 } else {
 333                         dev_warn(cs->dev, "could not allocate new skb\n");
 334                         inputstate |= INS_skip_frame;
 335                 }
 336         }
 337
 338         bcs->inputstate = inputstate;
 339         bcs->skb = skb;
 340         return startbytes - numbytes;
 341 }
 342
 343 /* process a block of data received from the device
 344  */
 345 void gigaset_m10x_input(struct inbuf_t *inbuf)
 346 {
 347         struct cardstate *cs;
 348         unsigned tail, head, numbytes;
 349         unsigned char *src, c;
 350         int procbytes;
 351
 352         head = atomic_read(&inbuf->head);
 353         tail = atomic_read(&inbuf->tail);
 354         gig_dbg(DEBUG_INTR, "buffer state: %u -> %u", head, tail);
 355
 356         if (head != tail) {
 357                 cs = inbuf->cs;
 358                 src = inbuf->data + head;
 359                 numbytes = (head > tail ? RBUFSIZE : tail) - head;
 360                 gig_dbg(DEBUG_INTR, "processing %u bytes", numbytes);
 361
 362                 while (numbytes) {
 363                         if (atomic_read(&cs->mstate) == MS_LOCKED) {
 364                                 procbytes = lock_loop(src, numbytes, inbuf);
 365                                 src += procbytes;
 366                                 numbytes -= procbytes;
 367                         } else {
 368                                 c = *src++;
 369                                 --numbytes;
 370                                 if (c == DLE_FLAG && (cs->dle ||
 371                                     inbuf->inputstate & INS_DLE_command)) {
 372                                         if (!(inbuf->inputstate & INS_DLE_char)) {
 373                                                 inbuf->inputstate |= INS_DLE_char;
 374                                                 goto nextbyte;
 375                                         }
 376                                         /* <DLE> <DLE> => <DLE> in data stream */
 377                                         inbuf->inputstate &= ~INS_DLE_char;
 378                                 }
 379
 380                                 if (!(inbuf->inputstate & INS_DLE_char)) {
 381
 382                                         /* FIXME use function pointers?  */
 383                                         if (inbuf->inputstate & INS_command)
 384                                                 procbytes = cmd_loop(c, src, numbytes, inbuf);
 385                                         else if (inbuf->bcs->proto2 == ISDN_PROTO_L2_HDLC)
 386                                                 procbytes = hdlc_loop(c, src, numbytes, inbuf);
 387                                         else
 388                                                 procbytes = iraw_loop(c, src, numbytes, inbuf);
 389
 390                                         src += procbytes;
 391                                         numbytes -= procbytes;
 392                                 } else {  /* DLE char */
 393                                         inbuf->inputstate &= ~INS_DLE_char;
 394                                         switch (c) {
 395                                         case 'X': /*begin of command*/
 396 #ifdef CONFIG_GIGASET_DEBUG
 397                                                 if (inbuf->inputstate & INS_command)
 398                                                         dev_err(cs->dev,
 399                                         "received <DLE> 'X' in command mode\n");
 400 #endif
 401                                                 inbuf->inputstate |=
 402                                                         INS_command | INS_DLE_command;
 403                                                 break;
 404                                         case '.': /*end of command*/
 405 #ifdef CONFIG_GIGASET_DEBUG
 406                                                 if (!(inbuf->inputstate & INS_command))
 407                                                         dev_err(cs->dev,
 408                                         "received <DLE> '.' in hdlc mode\n");
 409 #endif
 410                                                 inbuf->inputstate &= cs->dle ?
 411                                                         ~(INS_DLE_command|INS_command)
 412                                                         : ~INS_DLE_command;
 413                                                 break;
 414                                         //case DLE_FLAG: /*DLE_FLAG in data stream*/ /* schon oben behandelt! */
 415                                         default:
 416                                                 dev_err(cs->dev,
 417                                                       "received 0x10 0x%02x!\n",
 418                                                         (int) c);
 419                                                 /* FIXME: reset driver?? */
 420                                         }
 421                                 }
 422                         }
 423 nextbyte:
 424                         if (!numbytes) {
 425                                 /* end of buffer, check for wrap */
 426                                 if (head > tail) {
 427                                         head = 0;
 428                                         src = inbuf->data;
 429                                         numbytes = tail;
 430                                 } else {
 431                                         head = tail;
 432                                         break;
 433                                 }
 434                         }
 435                 }
 436
 437                 gig_dbg(DEBUG_INTR, "setting head to %u", head);
 438                 atomic_set(&inbuf->head, head);
 439         }
 440 }
 441
 442
 443 /* == data output ========================================================== */
 444
 445 /* Encoding of a PPP packet into an octet stuffed HDLC frame
 446  * with FCS, opening and closing flags.
 447  * parameters:
 448  *      skb     skb containing original packet (freed upon return)
 449  *      head    number of headroom bytes to allocate in result skb
 450  *      tail    number of tailroom bytes to allocate in result skb
 451  * Return value:
 452  *      pointer to newly allocated skb containing the result frame
 453  */
 454 static struct sk_buff *HDLC_Encode(struct sk_buff *skb, int head, int tail)
 455 {
 456         struct sk_buff *hdlc_skb;
 457         __u16 fcs;
 458         unsigned char c;
 459         unsigned char *cp;
 460         int len;
 461         unsigned int stuf_cnt;
 462
 463         stuf_cnt = 0;
 464         fcs = PPP_INITFCS;
 465         cp = skb->data;
 466         len = skb->len;
 467         while (len--) {
 468                 if (muststuff(*cp))
 469                         stuf_cnt++;
 470                 fcs = crc_ccitt_byte(fcs, *cp++);
 471         }
 472         fcs ^= 0xffff;                  /* complement */
 473
 474         /* size of new buffer: original size + number of stuffing bytes
 475          * + 2 bytes FCS + 2 stuffing bytes for FCS (if needed) + 2 flag bytes
 476          */
 477         hdlc_skb = dev_alloc_skb(skb->len + stuf_cnt + 6 + tail + head);
 478         if (!hdlc_skb) {
 479                 dev_kfree_skb(skb);
 480                 return NULL;
 481         }
 482         skb_reserve(hdlc_skb, head);
 483
 484         /* Copy acknowledge request into new skb */
 485         memcpy(hdlc_skb->head, skb->head, 2);
 486
 487         /* Add flag sequence in front of everything.. */
 488         *(skb_put(hdlc_skb, 1)) = PPP_FLAG;
 489
 490         /* Perform byte stuffing while copying data. */
 491         while (skb->len--) {
 492                 if (muststuff(*skb->data)) {
 493                         *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
 494                         *(skb_put(hdlc_skb, 1)) = (*skb->data++) ^ PPP_TRANS;
 495                 } else
 496                         *(skb_put(hdlc_skb, 1)) = *skb->data++;
 497         }
 498
 499         /* Finally add FCS (byte stuffed) and flag sequence */
 500         c = (fcs & 0x00ff);     /* least significant byte first */
 501         if (muststuff(c)) {
 502                 *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
 503                 c ^= PPP_TRANS;
 504         }
 505         *(skb_put(hdlc_skb, 1)) = c;
 506
 507         c = ((fcs >> 8) & 0x00ff);
 508         if (muststuff(c)) {
 509                 *(skb_put(hdlc_skb, 1)) = PPP_ESCAPE;
 510                 c ^= PPP_TRANS;
 511         }
 512         *(skb_put(hdlc_skb, 1)) = c;
 513
 514         *(skb_put(hdlc_skb, 1)) = PPP_FLAG;
 515
 516         dev_kfree_skb(skb);
 517         return hdlc_skb;
 518 }
 519
 520 /* Encoding of a raw packet into an octet stuffed bit inverted frame
 521  * parameters:
 522  *      skb     skb containing original packet (freed upon return)
 523  *      head    number of headroom bytes to allocate in result skb
 524  *      tail    number of tailroom bytes to allocate in result skb
 525  * Return value:
 526  *      pointer to newly allocated skb containing the result frame
 527  */
 528 static struct sk_buff *iraw_encode(struct sk_buff *skb, int head, int tail)
 529 {
 530         struct sk_buff *iraw_skb;
 531         unsigned char c;
 532         unsigned char *cp;
 533         int len;
 534
 535         /* worst case: every byte must be stuffed */
 536         iraw_skb = dev_alloc_skb(2*skb->len + tail + head);
 537         if (!iraw_skb) {
 538                 dev_kfree_skb(skb);
 539                 return NULL;
 540         }
 541         skb_reserve(iraw_skb, head);
 542
 543         cp = skb->data;
 544         len = skb->len;
 545         while (len--) {
 546                 c = gigaset_invtab[*cp++];
 547                 if (c == DLE_FLAG)
 548                         *(skb_put(iraw_skb, 1)) = c;
 549                 *(skb_put(iraw_skb, 1)) = c;
 550         }
 551         dev_kfree_skb(skb);
 552         return iraw_skb;
 553 }
 554
 555 /* gigaset_send_skb
 556  * called by common.c to queue an skb for sending
 557  * and start transmission if necessary
 558  * parameters:
 559  *      B Channel control structure
 560  *      skb
 561  * Return value:
 562  *      number of bytes accepted for sending
 563  *      (skb->len if ok, 0 if out of buffer space)
 564  *      or error code (< 0, eg. -EINVAL)
 565  */
 566 int gigaset_m10x_send_skb(struct bc_state *bcs, struct sk_buff *skb)
 567 {
 568         unsigned len = skb->len;
 569         unsigned long flags;
 570
 571         if (bcs->proto2 == ISDN_PROTO_L2_HDLC)
 572                 skb = HDLC_Encode(skb, HW_HDR_LEN, 0);
 573         else
 574                 skb = iraw_encode(skb, HW_HDR_LEN, 0);
 575         if (!skb) {
 576                 err("unable to allocate memory for encoding!\n");
 577                 return -ENOMEM;
 578         }
 579
 580         skb_queue_tail(&bcs->squeue, skb);
 581         spin_lock_irqsave(&bcs->cs->lock, flags);
 582         if (bcs->cs->connected)
 583                 tasklet_schedule(&bcs->cs->write_tasklet);
 584         spin_unlock_irqrestore(&bcs->cs->lock, flags);
 585
 586         return len;     /* ok so far */
 587 }