drivers/char/n_r3964.c

   1 /* r3964 linediscipline for linux
   2  *
   3  * -----------------------------------------------------------
   4  * Copyright by
   5  * Philips Automation Projects
   6  * Kassel (Germany)
   7  * http://www.pap-philips.de
   8  * -----------------------------------------------------------
   9  * This software may be used and distributed according to the terms of
  10  * the GNU General Public License, incorporated herein by reference.
  11  *
  12  * Author:
  13  * L. Haag
  14  *
  15  * $Log: n_r3964.c,v $
  16  * Revision 1.10  2001/03/18 13:02:24  dwmw2
  17  * Fix timer usage, use spinlocks properly.
  18  *
  19  * Revision 1.9  2001/03/18 12:52:14  dwmw2
  20  * Merge changes in 2.4.2
  21  *
  22  * Revision 1.8  2000/03/23 14:14:54  dwmw2
  23  * Fix race in sleeping in r3964_read()
  24  *
  25  * Revision 1.7  1999/28/08 11:41:50  dwmw2
  26  * Port to 2.3 kernel
  27  *
  28  * Revision 1.6  1998/09/30 00:40:40  dwmw2
  29  * Fixed compilation on 2.0.x kernels
  30  * Updated to newly registered tty-ldisc number 9
  31  *
  32  * Revision 1.5  1998/09/04 21:57:36  dwmw2
  33  * Signal handling bug fixes, port to 2.1.x.
  34  *
  35  * Revision 1.4  1998/04/02 20:26:59  lhaag
  36  * select, blocking, ...
  37  *
  38  * Revision 1.3  1998/02/12 18:58:43  root
  39  * fixed some memory leaks
  40  * calculation of checksum characters
  41  *
  42  * Revision 1.2  1998/02/07 13:03:34  root
  43  * ioctl read_telegram
  44  *
  45  * Revision 1.1  1998/02/06 19:21:03  root
  46  * Initial revision
  47  *
  48  *
  49  */
  50
  51 #include <linux/module.h>
  52 #include <linux/kernel.h>
  53 #include <linux/sched.h>
  54 #include <linux/types.h>
  55 #include <linux/fcntl.h>
  56 #include <linux/interrupt.h>
  57 #include <linux/ptrace.h>
  58 #include <linux/ioport.h>
  59 #include <linux/in.h>
  60 #include <linux/slab.h>
  61 #include <linux/tty.h>
  62 #include <linux/errno.h>
  63 #include <linux/string.h>   /* used in new tty drivers */
  64 #include <linux/signal.h>   /* used in new tty drivers */
  65 #include <linux/ioctl.h>
  66 #include <linux/n_r3964.h>
  67 #include <linux/poll.h>
  68 #include <linux/init.h>
  69 #include <asm/uaccess.h>
  70
  71
  72 //#define DEBUG_QUEUE
  73
  74 /* Log successful handshake and protocol operations  */
  75 //#define DEBUG_PROTO_S
  76
  77 /* Log handshake and protocol errors: */
  78 //#define DEBUG_PROTO_E
  79
  80 /* Log Linediscipline operations (open, close, read, write...): */
  81 //#define DEBUG_LDISC
  82
  83 /* Log module and memory operations (init, cleanup; kmalloc, kfree): */
  84 //#define DEBUG_MODUL
  85
  86 /* Macro helpers for debug output: */
  87 #define TRACE(format, args...) printk("r3964: " format "\n" , ## args);
  88
  89 #ifdef DEBUG_MODUL
  90 #define TRACE_M(format, args...) printk("r3964: " format "\n" , ## args);
  91 #else
  92 #define TRACE_M(fmt, arg...) /**/
  93 #endif
  94
  95 #ifdef DEBUG_PROTO_S
  96 #define TRACE_PS(format, args...) printk("r3964: " format "\n" , ## args);
  97 #else
  98 #define TRACE_PS(fmt, arg...) /**/
  99 #endif
 100
 101 #ifdef DEBUG_PROTO_E
 102 #define TRACE_PE(format, args...) printk("r3964: " format "\n" , ## args);
 103 #else
 104 #define TRACE_PE(fmt, arg...) /**/
 105 #endif
 106
 107 #ifdef DEBUG_LDISC
 108 #define TRACE_L(format, args...) printk("r3964: " format "\n" , ## args);
 109 #else
 110 #define TRACE_L(fmt, arg...) /**/
 111 #endif
 112
 113 #ifdef DEBUG_QUEUE
 114 #define TRACE_Q(format, args...) printk("r3964: " format "\n" , ## args);
 115 #else
 116 #define TRACE_Q(fmt, arg...) /**/
 117 #endif
 118
 119 static void add_tx_queue(struct r3964_info *, struct r3964_block_header *);
 120 static void remove_from_tx_queue(struct r3964_info *pInfo, int error_code);
 121 static void put_char(struct r3964_info *pInfo, unsigned char ch);
 122 static void trigger_transmit(struct r3964_info *pInfo);
 123 static void retry_transmit(struct r3964_info *pInfo);
 124 static void transmit_block(struct r3964_info *pInfo);
 125 static void receive_char(struct r3964_info *pInfo, const unsigned char c);
 126 static void receive_error(struct r3964_info *pInfo, const char flag);
 127 static void on_timeout(unsigned long priv);
 128 static int enable_signals(struct r3964_info *pInfo, pid_t pid, int arg);
 129 static int read_telegram(struct r3964_info *pInfo, pid_t pid, unsigned char __user *buf);
 130 static void add_msg(struct r3964_client_info *pClient, int msg_id, int arg,
 131              int error_code, struct r3964_block_header *pBlock);
 132 static struct r3964_message* remove_msg(struct r3964_info *pInfo,
 133              struct r3964_client_info *pClient);
 134 static void remove_client_block(struct r3964_info *pInfo,
 135                 struct r3964_client_info *pClient);
 136
 137 static int  r3964_open(struct tty_struct *tty);
 138 static void r3964_close(struct tty_struct *tty);
 139 static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 140                      unsigned char __user *buf, size_t nr);
 141 static ssize_t r3964_write(struct tty_struct * tty, struct file * file,
 142                       const unsigned char * buf, size_t nr);
 143 static int r3964_ioctl(struct tty_struct * tty, struct file * file,
 144                        unsigned int cmd, unsigned long arg);
 145 static void r3964_set_termios(struct tty_struct *tty, struct ktermios * old);
 146 static unsigned int r3964_poll(struct tty_struct * tty, struct file * file,
 147                       struct poll_table_struct  *wait);
 148 static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 149                               char *fp, int count);
 150
 151 static struct tty_ldisc tty_ldisc_N_R3964 = {
 152         .owner   = THIS_MODULE,
 153         .magic  = TTY_LDISC_MAGIC,
 154         .name   = "R3964",
 155         .open   = r3964_open,
 156         .close  = r3964_close,
 157         .read   = r3964_read,
 158         .write  = r3964_write,
 159         .ioctl  = r3964_ioctl,
 160         .set_termios = r3964_set_termios,
 161         .poll   = r3964_poll,
 162         .receive_buf = r3964_receive_buf,
 163 };
 164
 165
 166
 167 static void dump_block(const unsigned char *block, unsigned int length)
 168 {
 169    unsigned int i,j;
 170    char linebuf[16*3+1];
 171
 172    for(i=0;i<length;i+=16)
 173    {
 174       for(j=0;(j<16) && (j+i<length);j++)
 175       {
 176          sprintf(linebuf+3*j,"%02x ",block[i+j]);
 177       }
 178       linebuf[3*j]='\0';
 179       TRACE_PS("%s",linebuf);
 180    }
 181 }
 182
 183
 184
 185
 186 /*************************************************************
 187  * Driver initialisation
 188  *************************************************************/
 189
 190
 191 /*************************************************************
 192  * Module support routines
 193  *************************************************************/
 194
 195 static void __exit r3964_exit(void)
 196 {
 197    int status;
 198
 199    TRACE_M ("cleanup_module()");
 200
 201    status=tty_unregister_ldisc(N_R3964);
 202
 203    if(status!=0)
 204    {
 205       printk(KERN_ERR "r3964: error unregistering linediscipline: %d\n", status);
 206    }
 207    else
 208    {
 209       TRACE_L("linediscipline successfully unregistered");
 210    }
 211
 212 }
 213
 214 static int __init r3964_init(void)
 215 {
 216    int status;
 217
 218    printk ("r3964: Philips r3964 Driver $Revision: 1.10 $\n");
 219
 220    /*
 221     * Register the tty line discipline
 222     */
 223
 224    status = tty_register_ldisc (N_R3964, &tty_ldisc_N_R3964);
 225    if (status == 0)
 226      {
 227        TRACE_L("line discipline %d registered", N_R3964);
 228        TRACE_L("flags=%x num=%x", tty_ldisc_N_R3964.flags,
 229                tty_ldisc_N_R3964.num);
 230        TRACE_L("open=%p", tty_ldisc_N_R3964.open);
 231        TRACE_L("tty_ldisc_N_R3964 = %p", &tty_ldisc_N_R3964);
 232      }
 233    else
 234      {
 235        printk (KERN_ERR "r3964: error registering line discipline: %d\n", status);
 236      }
 237    return status;
 238 }
 239
 240 module_init(r3964_init);
 241 module_exit(r3964_exit);
 242
 243
 244 /*************************************************************
 245  * Protocol implementation routines
 246  *************************************************************/
 247
 248 static void add_tx_queue(struct r3964_info *pInfo, struct r3964_block_header *pHeader)
 249 {
 250    unsigned long flags;
 251
 252    spin_lock_irqsave(&pInfo->lock, flags);
 253
 254    pHeader->next = NULL;
 255
 256    if(pInfo->tx_last == NULL)
 257    {
 258       pInfo->tx_first = pInfo->tx_last = pHeader;
 259    }
 260    else
 261    {
 262       pInfo->tx_last->next = pHeader;
 263       pInfo->tx_last = pHeader;
 264    }
 265
 266    spin_unlock_irqrestore(&pInfo->lock, flags);
 267
 268    TRACE_Q("add_tx_queue %p, length %d, tx_first = %p",
 269           pHeader, pHeader->length, pInfo->tx_first );
 270 }
 271
 272 static void remove_from_tx_queue(struct r3964_info *pInfo, int error_code)
 273 {
 274    struct r3964_block_header *pHeader;
 275    unsigned long flags;
 276 #ifdef DEBUG_QUEUE
 277    struct r3964_block_header *pDump;
 278 #endif
 279
 280    pHeader = pInfo->tx_first;
 281
 282    if(pHeader==NULL)
 283       return;
 284
 285 #ifdef DEBUG_QUEUE
 286    printk("r3964: remove_from_tx_queue: %p, length %u - ",
 287           pHeader, pHeader->length );
 288    for(pDump=pHeader;pDump;pDump=pDump->next)
 289          printk("%p ", pDump);
 290    printk("\n");
 291 #endif
 292
 293
 294    if(pHeader->owner)
 295    {
 296       if(error_code)
 297       {
 298           add_msg(pHeader->owner, R3964_MSG_ACK, 0,
 299                   error_code, NULL);
 300       }
 301       else
 302       {
 303           add_msg(pHeader->owner, R3964_MSG_ACK, pHeader->length,
 304                   error_code, NULL);
 305       }
 306       wake_up_interruptible (&pInfo->read_wait);
 307    }
 308
 309    spin_lock_irqsave(&pInfo->lock, flags);
 310
 311    pInfo->tx_first = pHeader->next;
 312    if(pInfo->tx_first==NULL)
 313    {
 314       pInfo->tx_last = NULL;
 315    }
 316
 317    spin_unlock_irqrestore(&pInfo->lock, flags);
 318
 319    kfree(pHeader);
 320    TRACE_M("remove_from_tx_queue - kfree %p",pHeader);
 321
 322    TRACE_Q("remove_from_tx_queue: tx_first = %p, tx_last = %p",
 323           pInfo->tx_first, pInfo->tx_last );
 324 }
 325
 326 static void add_rx_queue(struct r3964_info *pInfo, struct r3964_block_header *pHeader)
 327 {
 328    unsigned long flags;
 329
 330    spin_lock_irqsave(&pInfo->lock, flags);
 331
 332    pHeader->next = NULL;
 333
 334    if(pInfo->rx_last == NULL)
 335    {
 336       pInfo->rx_first = pInfo->rx_last = pHeader;
 337    }
 338    else
 339    {
 340       pInfo->rx_last->next = pHeader;
 341       pInfo->rx_last = pHeader;
 342    }
 343    pInfo->blocks_in_rx_queue++;
 344
 345    spin_unlock_irqrestore(&pInfo->lock, flags);
 346
 347    TRACE_Q("add_rx_queue: %p, length = %d, rx_first = %p, count = %d",
 348           pHeader, pHeader->length,
 349           pInfo->rx_first, pInfo->blocks_in_rx_queue);
 350 }
 351
 352 static void remove_from_rx_queue(struct r3964_info *pInfo,
 353                  struct r3964_block_header *pHeader)
 354 {
 355    unsigned long flags;
 356    struct r3964_block_header *pFind;
 357
 358    if(pHeader==NULL)
 359       return;
 360
 361    TRACE_Q("remove_from_rx_queue: rx_first = %p, rx_last = %p, count = %d",
 362           pInfo->rx_first, pInfo->rx_last, pInfo->blocks_in_rx_queue );
 363    TRACE_Q("remove_from_rx_queue: %p, length %u",
 364           pHeader, pHeader->length );
 365
 366    spin_lock_irqsave(&pInfo->lock, flags);
 367
 368    if(pInfo->rx_first == pHeader)
 369    {
 370       /* Remove the first block in the linked list: */
 371       pInfo->rx_first = pHeader->next;
 372
 373       if(pInfo->rx_first==NULL)
 374       {
 375          pInfo->rx_last = NULL;
 376       }
 377       pInfo->blocks_in_rx_queue--;
 378    }
 379    else
 380    {
 381       /* Find block to remove: */
 382       for(pFind=pInfo->rx_first; pFind; pFind=pFind->next)
 383       {
 384          if(pFind->next == pHeader)
 385          {
 386             /* Got it. */
 387             pFind->next = pHeader->next;
 388             pInfo->blocks_in_rx_queue--;
 389             if(pFind->next==NULL)
 390             {
 391                /* Oh, removed the last one! */
 392                pInfo->rx_last = pFind;
 393             }
 394             break;
 395          }
 396       }
 397    }
 398
 399    spin_unlock_irqrestore(&pInfo->lock, flags);
 400
 401    kfree(pHeader);
 402    TRACE_M("remove_from_rx_queue - kfree %p",pHeader);
 403
 404    TRACE_Q("remove_from_rx_queue: rx_first = %p, rx_last = %p, count = %d",
 405           pInfo->rx_first, pInfo->rx_last, pInfo->blocks_in_rx_queue );
 406 }
 407
 408 static void put_char(struct r3964_info *pInfo, unsigned char ch)
 409 {
 410    struct tty_struct *tty = pInfo->tty;
 411
 412    if(tty==NULL)
 413       return;
 414
 415    if(tty->driver->put_char)
 416    {
 417       tty->driver->put_char(tty, ch);
 418    }
 419    pInfo->bcc ^= ch;
 420 }
 421
 422 static void flush(struct r3964_info *pInfo)
 423 {
 424    struct tty_struct *tty = pInfo->tty;
 425
 426    if(tty==NULL)
 427       return;
 428
 429    if(tty->driver->flush_chars)
 430    {
 431       tty->driver->flush_chars(tty);
 432    }
 433 }
 434
 435 static void trigger_transmit(struct r3964_info *pInfo)
 436 {
 437    unsigned long flags;
 438
 439
 440    spin_lock_irqsave(&pInfo->lock, flags);
 441
 442    if((pInfo->state == R3964_IDLE) && (pInfo->tx_first!=NULL))
 443    {
 444       pInfo->state = R3964_TX_REQUEST;
 445       pInfo->nRetry=0;
 446       pInfo->flags &= ~R3964_ERROR;
 447       mod_timer(&pInfo->tmr, jiffies + R3964_TO_QVZ);
 448
 449       spin_unlock_irqrestore(&pInfo->lock, flags);
 450
 451       TRACE_PS("trigger_transmit - sent STX");
 452
 453       put_char(pInfo, STX);
 454       flush(pInfo);
 455
 456       pInfo->bcc = 0;
 457    }
 458    else
 459    {
 460       spin_unlock_irqrestore(&pInfo->lock, flags);
 461    }
 462 }
 463
 464 static void retry_transmit(struct r3964_info *pInfo)
 465 {
 466    if(pInfo->nRetry<R3964_MAX_RETRIES)
 467    {
 468       TRACE_PE("transmission failed. Retry #%d",
 469              pInfo->nRetry);
 470       pInfo->bcc = 0;
 471       put_char(pInfo, STX);
 472       flush(pInfo);
 473       pInfo->state = R3964_TX_REQUEST;
 474       pInfo->nRetry++;
 475       mod_timer(&pInfo->tmr, jiffies + R3964_TO_QVZ);
 476    }
 477    else
 478    {
 479       TRACE_PE("transmission failed after %d retries",
 480              R3964_MAX_RETRIES);
 481
 482       remove_from_tx_queue(pInfo, R3964_TX_FAIL);
 483
 484       put_char(pInfo, NAK);
 485       flush(pInfo);
 486       pInfo->state = R3964_IDLE;
 487
 488       trigger_transmit(pInfo);
 489    }
 490 }
 491
 492
 493 static void transmit_block(struct r3964_info *pInfo)
 494 {
 495    struct tty_struct *tty = pInfo->tty;
 496    struct r3964_block_header *pBlock = pInfo->tx_first;
 497    int room=0;
 498
 499    if((tty==NULL) || (pBlock==NULL))
 500    {
 501       return;
 502    }
 503
 504    if(tty->driver->write_room)
 505       room=tty->driver->write_room(tty);
 506
 507    TRACE_PS("transmit_block %p, room %d, length %d",
 508           pBlock, room, pBlock->length);
 509
 510    while(pInfo->tx_position < pBlock->length)
 511    {
 512       if(room<2)
 513          break;
 514
 515       if(pBlock->data[pInfo->tx_position]==DLE)
 516       {
 517          /* send additional DLE char: */
 518          put_char(pInfo, DLE);
 519       }
 520       put_char(pInfo, pBlock->data[pInfo->tx_position++]);
 521
 522       room--;
 523    }
 524
 525    if((pInfo->tx_position == pBlock->length) && (room>=3))
 526    {
 527       put_char(pInfo, DLE);
 528       put_char(pInfo, ETX);
 529       if(pInfo->flags & R3964_BCC)
 530       {
 531          put_char(pInfo, pInfo->bcc);
 532       }
 533       pInfo->state = R3964_WAIT_FOR_TX_ACK;
 534       mod_timer(&pInfo->tmr, jiffies + R3964_TO_QVZ);
 535    }
 536    flush(pInfo);
 537 }
 538
 539 static void on_receive_block(struct r3964_info *pInfo)
 540 {
 541    unsigned int length;
 542    struct r3964_client_info *pClient;
 543    struct r3964_block_header *pBlock;
 544
 545    length=pInfo->rx_position;
 546
 547    /* compare byte checksum characters: */
 548    if(pInfo->flags & R3964_BCC)
 549    {
 550       if(pInfo->bcc!=pInfo->last_rx)
 551       {
 552          TRACE_PE("checksum error - got %x but expected %x",
 553                 pInfo->last_rx, pInfo->bcc);
 554          pInfo->flags |= R3964_CHECKSUM;
 555       }
 556    }
 557
 558    /* check for errors (parity, overrun,...): */
 559    if(pInfo->flags & R3964_ERROR)
 560    {
 561       TRACE_PE("on_receive_block - transmission failed error %x",
 562              pInfo->flags & R3964_ERROR);
 563
 564       put_char(pInfo, NAK);
 565       flush(pInfo);
 566       if(pInfo->nRetry<R3964_MAX_RETRIES)
 567       {
 568          pInfo->state=R3964_WAIT_FOR_RX_REPEAT;
 569          pInfo->nRetry++;
 570          mod_timer(&pInfo->tmr, jiffies + R3964_TO_RX_PANIC);
 571       }
 572       else
 573       {
 574          TRACE_PE("on_receive_block - failed after max retries");
 575          pInfo->state=R3964_IDLE;
 576       }
 577       return;
 578    }
 579
 580
 581    /* received block; submit DLE: */
 582    put_char(pInfo, DLE);
 583    flush(pInfo);
 584    del_timer_sync(&pInfo->tmr);
 585    TRACE_PS(" rx success: got %d chars", length);
 586
 587    /* prepare struct r3964_block_header: */
 588    pBlock = kmalloc(length+sizeof(struct r3964_block_header), GFP_KERNEL);
 589    TRACE_M("on_receive_block - kmalloc %p",pBlock);
 590
 591    if(pBlock==NULL)
 592       return;
 593
 594    pBlock->length = length;
 595    pBlock->data   = ((unsigned char*)pBlock)+sizeof(struct r3964_block_header);
 596    pBlock->locks  = 0;
 597    pBlock->next   = NULL;
 598    pBlock->owner  = NULL;
 599
 600    memcpy(pBlock->data, pInfo->rx_buf, length);
 601
 602    /* queue block into rx_queue: */
 603    add_rx_queue(pInfo, pBlock);
 604
 605    /* notify attached client processes: */
 606    for(pClient=pInfo->firstClient; pClient; pClient=pClient->next)
 607    {
 608       if(pClient->sig_flags & R3964_SIG_DATA)
 609       {
 610          add_msg(pClient, R3964_MSG_DATA, length, R3964_OK, pBlock);
 611       }
 612    }
 613    wake_up_interruptible (&pInfo->read_wait);
 614
 615    pInfo->state = R3964_IDLE;
 616
 617    trigger_transmit(pInfo);
 618 }
 619
 620
 621 static void receive_char(struct r3964_info *pInfo, const unsigned char c)
 622 {
 623    switch(pInfo->state)
 624    {
 625       case R3964_TX_REQUEST:
 626          if(c==DLE)
 627          {
 628             TRACE_PS("TX_REQUEST - got DLE");
 629
 630             pInfo->state = R3964_TRANSMITTING;
 631             pInfo->tx_position = 0;
 632
 633             transmit_block(pInfo);
 634          }
 635          else if(c==STX)
 636          {
 637             if(pInfo->nRetry==0)
 638             {
 639                TRACE_PE("TX_REQUEST - init conflict");
 640                if(pInfo->priority == R3964_SLAVE)
 641                {
 642                   goto start_receiving;
 643                }
 644             }
 645             else
 646             {
 647                TRACE_PE("TX_REQUEST - secondary init conflict!?"
 648                         " Switching to SLAVE mode for next rx.");
 649                goto start_receiving;
 650             }
 651          }
 652          else
 653          {
 654             TRACE_PE("TX_REQUEST - char != DLE: %x", c);
 655             retry_transmit(pInfo);
 656          }
 657          break;
 658       case R3964_TRANSMITTING:
 659          if(c==NAK)
 660          {
 661             TRACE_PE("TRANSMITTING - got NAK");
 662             retry_transmit(pInfo);
 663          }
 664          else
 665          {
 666             TRACE_PE("TRANSMITTING - got invalid char");
 667
 668             pInfo->state = R3964_WAIT_ZVZ_BEFORE_TX_RETRY;
 669             mod_timer(&pInfo->tmr, jiffies + R3964_TO_ZVZ);
 670          }
 671          break;
 672       case R3964_WAIT_FOR_TX_ACK:
 673          if(c==DLE)
 674          {
 675             TRACE_PS("WAIT_FOR_TX_ACK - got DLE");
 676             remove_from_tx_queue(pInfo, R3964_OK);
 677
 678             pInfo->state = R3964_IDLE;
 679             trigger_transmit(pInfo);
 680          }
 681          else
 682          {
 683             retry_transmit(pInfo);
 684          }
 685          break;
 686       case R3964_WAIT_FOR_RX_REPEAT:
 687          /* FALLTROUGH */
 688       case R3964_IDLE:
 689          if(c==STX)
 690          {
 691             /* Prevent rx_queue from overflow: */
 692             if(pInfo->blocks_in_rx_queue >= R3964_MAX_BLOCKS_IN_RX_QUEUE)
 693             {
 694                TRACE_PE("IDLE - got STX but no space in rx_queue!");
 695                pInfo->state=R3964_WAIT_FOR_RX_BUF;
 696                mod_timer(&pInfo->tmr, jiffies + R3964_TO_NO_BUF);
 697                break;
 698             }
 699 start_receiving:
 700             /* Ok, start receiving: */
 701             TRACE_PS("IDLE - got STX");
 702             pInfo->rx_position = 0;
 703             pInfo->last_rx = 0;
 704             pInfo->flags &= ~R3964_ERROR;
 705             pInfo->state=R3964_RECEIVING;
 706             mod_timer(&pInfo->tmr, jiffies + R3964_TO_ZVZ);
 707             pInfo->nRetry = 0;
 708             put_char(pInfo, DLE);
 709             flush(pInfo);
 710             pInfo->bcc = 0;
 711          }
 712          break;
 713       case R3964_RECEIVING:
 714          if(pInfo->rx_position < RX_BUF_SIZE)
 715          {
 716             pInfo->bcc ^= c;
 717
 718             if(c==DLE)
 719             {
 720                if(pInfo->last_rx==DLE)
 721                {
 722                   pInfo->last_rx = 0;
 723                   goto char_to_buf;
 724                }
 725                pInfo->last_rx = DLE;
 726                break;
 727             }
 728             else if((c==ETX) && (pInfo->last_rx==DLE))
 729             {
 730                if(pInfo->flags & R3964_BCC)
 731                {
 732                   pInfo->state = R3964_WAIT_FOR_BCC;
 733                   mod_timer(&pInfo->tmr, jiffies + R3964_TO_ZVZ);
 734                }
 735                else
 736                {
 737                   on_receive_block(pInfo);
 738                }
 739             }
 740             else
 741             {
 742                pInfo->last_rx = c;
 743 char_to_buf:
 744                pInfo->rx_buf[pInfo->rx_position++] = c;
 745                mod_timer(&pInfo->tmr, jiffies + R3964_TO_ZVZ);
 746             }
 747          }
 748         /* else: overflow-msg? BUF_SIZE>MTU; should not happen? */
 749          break;
 750       case R3964_WAIT_FOR_BCC:
 751          pInfo->last_rx = c;
 752          on_receive_block(pInfo);
 753          break;
 754    }
 755 }
 756
 757 static void receive_error(struct r3964_info *pInfo, const char flag)
 758 {
 759     switch (flag)
 760     {
 761     case TTY_NORMAL:
 762         break;
 763     case TTY_BREAK:
 764         TRACE_PE("received break")
 765         pInfo->flags |= R3964_BREAK;
 766         break;
 767     case TTY_PARITY:
 768         TRACE_PE("parity error")
 769         pInfo->flags |= R3964_PARITY;
 770         break;
 771     case TTY_FRAME:
 772         TRACE_PE("frame error")
 773         pInfo->flags |= R3964_FRAME;
 774         break;
 775     case TTY_OVERRUN:
 776         TRACE_PE("frame overrun")
 777         pInfo->flags |= R3964_OVERRUN;
 778         break;
 779     default:
 780         TRACE_PE("receive_error - unknown flag %d", flag);
 781         pInfo->flags |= R3964_UNKNOWN;
 782         break;
 783     }
 784 }
 785
 786 static void on_timeout(unsigned long priv)
 787 {
 788    struct r3964_info *pInfo = (void *)priv;
 789
 790    switch(pInfo->state)
 791    {
 792       case R3964_TX_REQUEST:
 793          TRACE_PE("TX_REQUEST - timeout");
 794          retry_transmit(pInfo);
 795          break;
 796       case R3964_WAIT_ZVZ_BEFORE_TX_RETRY:
 797          put_char(pInfo, NAK);
 798          flush(pInfo);
 799          retry_transmit(pInfo);
 800          break;
 801       case R3964_WAIT_FOR_TX_ACK:
 802          TRACE_PE("WAIT_FOR_TX_ACK - timeout");
 803          retry_transmit(pInfo);
 804          break;
 805       case R3964_WAIT_FOR_RX_BUF:
 806          TRACE_PE("WAIT_FOR_RX_BUF - timeout");
 807          put_char(pInfo, NAK);
 808          flush(pInfo);
 809          pInfo->state=R3964_IDLE;
 810          break;
 811       case R3964_RECEIVING:
 812          TRACE_PE("RECEIVING - timeout after %d chars",
 813                   pInfo->rx_position);
 814          put_char(pInfo, NAK);
 815          flush(pInfo);
 816          pInfo->state=R3964_IDLE;
 817          break;
 818       case R3964_WAIT_FOR_RX_REPEAT:
 819          TRACE_PE("WAIT_FOR_RX_REPEAT - timeout");
 820          pInfo->state=R3964_IDLE;
 821          break;
 822       case R3964_WAIT_FOR_BCC:
 823          TRACE_PE("WAIT_FOR_BCC - timeout");
 824          put_char(pInfo, NAK);
 825          flush(pInfo);
 826          pInfo->state=R3964_IDLE;
 827          break;
 828    }
 829 }
 830
 831 static struct r3964_client_info *findClient(
 832   struct r3964_info *pInfo, pid_t pid)
 833 {
 834    struct r3964_client_info *pClient;
 835
 836    for(pClient=pInfo->firstClient; pClient; pClient=pClient->next)
 837    {
 838       if(pClient->pid == pid)
 839       {
 840          return pClient;
 841       }
 842    }
 843    return NULL;
 844 }
 845
 846 static int enable_signals(struct r3964_info *pInfo, pid_t pid, int arg)
 847 {
 848    struct r3964_client_info *pClient;
 849    struct r3964_client_info **ppClient;
 850    struct r3964_message *pMsg;
 851
 852    if((arg & R3964_SIG_ALL)==0)
 853    {
 854       /* Remove client from client list */
 855       for(ppClient=&pInfo->firstClient; *ppClient; ppClient=&(*ppClient)->next)
 856       {
 857          pClient = *ppClient;
 858
 859          if(pClient->pid == pid)
 860          {
 861             TRACE_PS("removing client %d from client list", pid);
 862             *ppClient = pClient->next;
 863             while(pClient->msg_count)
 864             {
 865                pMsg=remove_msg(pInfo, pClient);
 866                if(pMsg)
 867                {
 868                   kfree(pMsg);
 869                   TRACE_M("enable_signals - msg kfree %p",pMsg);
 870                }
 871             }
 872             kfree(pClient);
 873             TRACE_M("enable_signals - kfree %p",pClient);
 874             return 0;
 875          }
 876       }
 877       return -EINVAL;
 878    }
 879    else
 880    {
 881       pClient=findClient(pInfo, pid);
 882       if(pClient)
 883       {
 884          /* update signal options */
 885          pClient->sig_flags=arg;
 886       }
 887       else
 888       {
 889          /* add client to client list */
 890          pClient=kmalloc(sizeof(struct r3964_client_info), GFP_KERNEL);
 891          TRACE_M("enable_signals - kmalloc %p",pClient);
 892          if(pClient==NULL)
 893             return -ENOMEM;
 894
 895          TRACE_PS("add client %d to client list", pid);
 896          spin_lock_init(&pClient->lock);
 897          pClient->sig_flags=arg;
 898          pClient->pid = pid;
 899          pClient->next=pInfo->firstClient;
 900          pClient->first_msg = NULL;
 901          pClient->last_msg = NULL;
 902          pClient->next_block_to_read = NULL;
 903          pClient->msg_count = 0;
 904          pInfo->firstClient=pClient;
 905       }
 906    }
 907
 908    return 0;
 909 }
 910
 911 static int read_telegram(struct r3964_info *pInfo, pid_t pid, unsigned char __user *buf)
 912 {
 913     struct r3964_client_info *pClient;
 914     struct r3964_block_header *block;
 915
 916     if(!buf)
 917     {
 918         return -EINVAL;
 919     }
 920
 921     pClient=findClient(pInfo,pid);
 922     if(pClient==NULL)
 923     {
 924        return -EINVAL;
 925     }
 926
 927     block=pClient->next_block_to_read;
 928     if(!block)
 929     {
 930        return 0;
 931     }
 932     else
 933     {
 934       if (copy_to_user (buf, block->data, block->length))
 935         return -EFAULT;
 936
 937        remove_client_block(pInfo, pClient);
 938        return block->length;
 939     }
 940
 941     return -EINVAL;
 942 }
 943
 944 static void add_msg(struct r3964_client_info *pClient, int msg_id, int arg,
 945              int error_code, struct r3964_block_header *pBlock)
 946 {
 947    struct r3964_message *pMsg;
 948    unsigned long flags;
 949
 950    if(pClient->msg_count<R3964_MAX_MSG_COUNT-1)
 951    {
 952 queue_the_message:
 953
 954       pMsg = kmalloc(sizeof(struct r3964_message),
 955                      error_code?GFP_ATOMIC:GFP_KERNEL);
 956       TRACE_M("add_msg - kmalloc %p",pMsg);
 957       if(pMsg==NULL) {
 958          return;
 959       }
 960
 961       spin_lock_irqsave(&pClient->lock, flags);
 962
 963       pMsg->msg_id = msg_id;
 964       pMsg->arg    = arg;
 965       pMsg->error_code = error_code;
 966       pMsg->block  = pBlock;
 967       pMsg->next   = NULL;
 968
 969       if(pClient->last_msg==NULL)
 970       {
 971          pClient->first_msg=pClient->last_msg=pMsg;
 972       }
 973       else
 974       {
 975          pClient->last_msg->next = pMsg;
 976          pClient->last_msg=pMsg;
 977       }
 978
 979       pClient->msg_count++;
 980
 981       if(pBlock!=NULL)
 982       {
 983          pBlock->locks++;
 984       }
 985       spin_unlock_irqrestore(&pClient->lock, flags);
 986    }
 987    else
 988    {
 989       if((pClient->last_msg->msg_id == R3964_MSG_ACK)
 990                  && (pClient->last_msg->error_code==R3964_OVERFLOW))
 991       {
 992          pClient->last_msg->arg++;
 993                  TRACE_PE("add_msg - inc prev OVERFLOW-msg");
 994       }
 995       else
 996       {
 997          msg_id = R3964_MSG_ACK;
 998          arg = 0;
 999                  error_code = R3964_OVERFLOW;
1000          pBlock = NULL;
1001                  TRACE_PE("add_msg - queue OVERFLOW-msg");
1002          goto queue_the_message;
1003       }
1004    }
1005    /* Send SIGIO signal to client process: */
1006    if(pClient->sig_flags & R3964_USE_SIGIO)
1007    {
1008       kill_proc(pClient->pid, SIGIO, 1);
1009    }
1010 }
1011
1012 static struct r3964_message *remove_msg(struct r3964_info *pInfo,
1013                        struct r3964_client_info *pClient)
1014 {
1015    struct r3964_message *pMsg=NULL;
1016    unsigned long flags;
1017
1018    if(pClient->first_msg)
1019    {
1020       spin_lock_irqsave(&pClient->lock, flags);
1021
1022       pMsg = pClient->first_msg;
1023       pClient->first_msg = pMsg->next;
1024       if(pClient->first_msg==NULL)
1025       {
1026          pClient->last_msg = NULL;
1027       }
1028
1029       pClient->msg_count--;
1030       if(pMsg->block)
1031       {
1032         remove_client_block(pInfo, pClient);
1033         pClient->next_block_to_read = pMsg->block;
1034       }
1035       spin_unlock_irqrestore(&pClient->lock, flags);
1036    }
1037    return pMsg;
1038 }
1039
1040 static void remove_client_block(struct r3964_info *pInfo,
1041                 struct r3964_client_info *pClient)
1042 {
1043     struct r3964_block_header *block;
1044
1045     TRACE_PS("remove_client_block PID %d", pClient->pid);
1046
1047     block=pClient->next_block_to_read;
1048     if(block)
1049     {
1050         block->locks--;
1051         if(block->locks==0)
1052         {
1053             remove_from_rx_queue(pInfo, block);
1054         }
1055     }
1056     pClient->next_block_to_read = NULL;
1057 }
1058
1059
1060 /*************************************************************
1061  * Line discipline routines
1062  *************************************************************/
1063
1064 static int r3964_open(struct tty_struct *tty)
1065 {
1066    struct r3964_info *pInfo;
1067
1068    TRACE_L("open");
1069    TRACE_L("tty=%p, PID=%d, disc_data=%p",
1070           tty, current->pid, tty->disc_data);
1071
1072    pInfo=kmalloc(sizeof(struct r3964_info), GFP_KERNEL);
1073    TRACE_M("r3964_open - info kmalloc %p",pInfo);
1074
1075    if(!pInfo)
1076    {
1077       printk(KERN_ERR "r3964: failed to alloc info structure\n");
1078       return -ENOMEM;
1079    }
1080
1081    pInfo->rx_buf = kmalloc(RX_BUF_SIZE, GFP_KERNEL);
1082    TRACE_M("r3964_open - rx_buf kmalloc %p",pInfo->rx_buf);
1083
1084    if(!pInfo->rx_buf)
1085    {
1086       printk(KERN_ERR "r3964: failed to alloc receive buffer\n");
1087       kfree(pInfo);
1088       TRACE_M("r3964_open - info kfree %p",pInfo);
1089       return -ENOMEM;
1090    }
1091
1092    pInfo->tx_buf = kmalloc(TX_BUF_SIZE, GFP_KERNEL);
1093    TRACE_M("r3964_open - tx_buf kmalloc %p",pInfo->tx_buf);
1094
1095    if(!pInfo->tx_buf)
1096    {
1097       printk(KERN_ERR "r3964: failed to alloc transmit buffer\n");
1098       kfree(pInfo->rx_buf);
1099       TRACE_M("r3964_open - rx_buf kfree %p",pInfo->rx_buf);
1100       kfree(pInfo);
1101       TRACE_M("r3964_open - info kfree %p",pInfo);
1102       return -ENOMEM;
1103    }
1104
1105    spin_lock_init(&pInfo->lock);
1106    pInfo->tty = tty;
1107    init_waitqueue_head (&pInfo->read_wait);
1108    pInfo->priority = R3964_MASTER;
1109    pInfo->rx_first = pInfo->rx_last = NULL;
1110    pInfo->tx_first = pInfo->tx_last = NULL;
1111    pInfo->rx_position = 0;
1112    pInfo->tx_position = 0;
1113    pInfo->last_rx = 0;
1114    pInfo->blocks_in_rx_queue = 0;
1115    pInfo->firstClient=NULL;
1116    pInfo->state=R3964_IDLE;
1117    pInfo->flags = R3964_DEBUG;
1118    pInfo->nRetry = 0;
1119
1120    tty->disc_data = pInfo;
1121    tty->receive_room = 65536;
1122
1123    init_timer(&pInfo->tmr);
1124    pInfo->tmr.data = (unsigned long)pInfo;
1125    pInfo->tmr.function = on_timeout;
1126
1127    return 0;
1128 }
1129
1130 static void r3964_close(struct tty_struct *tty)
1131 {
1132    struct r3964_info *pInfo=(struct r3964_info*)tty->disc_data;
1133    struct r3964_client_info *pClient, *pNext;
1134    struct r3964_message *pMsg;
1135    struct r3964_block_header *pHeader, *pNextHeader;
1136    unsigned long flags;
1137
1138    TRACE_L("close");
1139
1140     /*
1141      * Make sure that our task queue isn't activated.  If it
1142      * is, take it out of the linked list.
1143      */
1144     del_timer_sync(&pInfo->tmr);
1145
1146    /* Remove client-structs and message queues: */
1147     pClient=pInfo->firstClient;
1148     while(pClient)
1149     {
1150        pNext=pClient->next;
1151        while(pClient->msg_count)
1152        {
1153           pMsg=remove_msg(pInfo, pClient);
1154           if(pMsg)
1155           {
1156              kfree(pMsg);
1157              TRACE_M("r3964_close - msg kfree %p",pMsg);
1158           }
1159        }
1160        kfree(pClient);
1161        TRACE_M("r3964_close - client kfree %p",pClient);
1162        pClient=pNext;
1163     }
1164     /* Remove jobs from tx_queue: */
1165         spin_lock_irqsave(&pInfo->lock, flags);
1166         pHeader=pInfo->tx_first;
1167         pInfo->tx_first=pInfo->tx_last=NULL;
1168         spin_unlock_irqrestore(&pInfo->lock, flags);
1169
1170     while(pHeader)
1171         {
1172            pNextHeader=pHeader->next;
1173            kfree(pHeader);
1174            pHeader=pNextHeader;
1175         }
1176
1177     /* Free buffers: */
1178     wake_up_interruptible(&pInfo->read_wait);
1179     kfree(pInfo->rx_buf);
1180     TRACE_M("r3964_close - rx_buf kfree %p",pInfo->rx_buf);
1181     kfree(pInfo->tx_buf);
1182     TRACE_M("r3964_close - tx_buf kfree %p",pInfo->tx_buf);
1183     kfree(pInfo);
1184     TRACE_M("r3964_close - info kfree %p",pInfo);
1185 }
1186
1187 static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
1188                           unsigned char __user *buf, size_t nr)
1189 {
1190    struct r3964_info *pInfo=(struct r3964_info*)tty->disc_data;
1191    struct r3964_client_info *pClient;
1192    struct r3964_message *pMsg;
1193    struct r3964_client_message theMsg;
1194    DECLARE_WAITQUEUE (wait, current);
1195
1196    int pid = current->pid;
1197    int count;
1198
1199    TRACE_L("read()");
1200
1201    pClient=findClient(pInfo, pid);
1202    if(pClient)
1203    {
1204       pMsg = remove_msg(pInfo, pClient);
1205       if(pMsg==NULL)
1206       {
1207                  /* no messages available. */
1208          if (file->f_flags & O_NONBLOCK)
1209                  {
1210             return -EAGAIN;
1211                  }
1212          /* block until there is a message: */
1213          add_wait_queue(&pInfo->read_wait, &wait);
1214 repeat:
1215          current->state = TASK_INTERRUPTIBLE;
1216          pMsg = remove_msg(pInfo, pClient);
1217          if (!pMsg && !signal_pending(current))
1218                  {
1219             schedule();
1220             goto repeat;
1221          }
1222          current->state = TASK_RUNNING;
1223          remove_wait_queue(&pInfo->read_wait, &wait);
1224       }
1225
1226       /* If we still haven't got a message, we must have been signalled */
1227
1228       if (!pMsg) return -EINTR;
1229
1230       /* deliver msg to client process: */
1231       theMsg.msg_id = pMsg->msg_id;
1232       theMsg.arg    = pMsg->arg;
1233       theMsg.error_code = pMsg->error_code;
1234       count = sizeof(struct r3964_client_message);
1235
1236       kfree(pMsg);
1237       TRACE_M("r3964_read - msg kfree %p",pMsg);
1238
1239       if (copy_to_user(buf,&theMsg, count))
1240         return -EFAULT;
1241
1242       TRACE_PS("read - return %d", count);
1243       return count;
1244    }
1245    return -EPERM;
1246 }
1247
1248 static ssize_t r3964_write(struct tty_struct * tty, struct file * file,
1249                            const unsigned char *data, size_t count)
1250 {
1251    struct r3964_info *pInfo=(struct r3964_info*)tty->disc_data;
1252    struct r3964_block_header *pHeader;
1253    struct r3964_client_info *pClient;
1254    unsigned char *new_data;
1255    int pid;
1256
1257    TRACE_L("write request, %d characters", count);
1258 /*
1259  * Verify the pointers
1260  */
1261
1262    if(!pInfo)
1263       return -EIO;
1264
1265 /*
1266  * Ensure that the caller does not wish to send too much.
1267  */
1268    if (count > R3964_MTU)
1269    {
1270       if (pInfo->flags & R3964_DEBUG)
1271       {
1272          TRACE_L (KERN_WARNING
1273                  "r3964_write: truncating user packet "
1274                  "from %u to mtu %d", count, R3964_MTU);
1275       }
1276       count = R3964_MTU;
1277    }
1278 /*
1279  * Allocate a buffer for the data and copy it from the buffer with header prepended
1280  */
1281    new_data = kmalloc (count+sizeof(struct r3964_block_header), GFP_KERNEL);
1282    TRACE_M("r3964_write - kmalloc %p",new_data);
1283    if (new_data == NULL) {
1284       if (pInfo->flags & R3964_DEBUG)
1285       {
1286          printk (KERN_ERR
1287                "r3964_write: no memory\n");
1288       }
1289       return -ENOSPC;
1290    }
1291
1292    pHeader = (struct r3964_block_header *)new_data;
1293    pHeader->data = new_data + sizeof(struct r3964_block_header);
1294    pHeader->length = count;
1295    pHeader->locks = 0;
1296    pHeader->owner = NULL;
1297
1298    pid=current->pid;
1299
1300    pClient=findClient(pInfo, pid);
1301    if(pClient)
1302    {
1303       pHeader->owner = pClient;
1304    }
1305
1306    memcpy(pHeader->data, data, count); /* We already verified this */
1307
1308    if(pInfo->flags & R3964_DEBUG)
1309    {
1310       dump_block(pHeader->data, count);
1311    }
1312
1313 /*
1314  * Add buffer to transmit-queue:
1315  */
1316    add_tx_queue(pInfo, pHeader);
1317    trigger_transmit(pInfo);
1318
1319    return 0;
1320 }
1321
1322 static int r3964_ioctl(struct tty_struct * tty, struct file * file,
1323                unsigned int cmd, unsigned long arg)
1324 {
1325    struct r3964_info *pInfo=(struct r3964_info*)tty->disc_data;
1326    if(pInfo==NULL)
1327       return -EINVAL;
1328    switch(cmd)
1329    {
1330       case R3964_ENABLE_SIGNALS:
1331          return enable_signals(pInfo, current->pid, arg);
1332       case R3964_SETPRIORITY:
1333          if(arg<R3964_MASTER || arg>R3964_SLAVE)
1334             return -EINVAL;
1335          pInfo->priority = arg & 0xff;
1336          return 0;
1337       case R3964_USE_BCC:
1338              if(arg)
1339             pInfo->flags |= R3964_BCC;
1340          else
1341             pInfo->flags &= ~R3964_BCC;
1342          return 0;
1343       case R3964_READ_TELEGRAM:
1344          return read_telegram(pInfo, current->pid, (unsigned char __user *)arg);
1345       default:
1346          return -ENOIOCTLCMD;
1347    }
1348 }
1349
1350 static void r3964_set_termios(struct tty_struct *tty, struct ktermios * old)
1351 {
1352    TRACE_L("set_termios");
1353 }
1354
1355 /* Called without the kernel lock held - fine */
1356 static unsigned int r3964_poll(struct tty_struct * tty, struct file * file,
1357                       struct poll_table_struct *wait)
1358 {
1359    struct r3964_info *pInfo=(struct r3964_info*)tty->disc_data;
1360    int pid=current->pid;
1361    struct r3964_client_info *pClient;
1362    struct r3964_message *pMsg=NULL;
1363    unsigned long flags;
1364    int result = POLLOUT;
1365
1366    TRACE_L("POLL");
1367
1368    pClient=findClient(pInfo,pid);
1369    if(pClient)
1370      {
1371        poll_wait(file, &pInfo->read_wait, wait);
1372        spin_lock_irqsave(&pInfo->lock, flags);
1373        pMsg=pClient->first_msg;
1374        spin_unlock_irqrestore(&pInfo->lock, flags);
1375        if(pMsg)
1376            result |= POLLIN | POLLRDNORM;
1377      }
1378    else
1379      {
1380        result = -EINVAL;
1381      }
1382    return result;
1383 }
1384
1385 static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1386                               char *fp, int count)
1387 {
1388    struct r3964_info *pInfo=(struct r3964_info*)tty->disc_data;
1389     const unsigned char *p;
1390     char *f, flags = 0;
1391     int i;
1392
1393     for (i=count, p = cp, f = fp; i; i--, p++) {
1394         if (f)
1395             flags = *f++;
1396         if(flags==TTY_NORMAL)
1397         {
1398             receive_char(pInfo, *p);
1399         }
1400         else
1401         {
1402             receive_error(pInfo, flags);
1403         }
1404
1405     }
1406 }
1407
1408 MODULE_LICENSE("GPL");
1409 MODULE_ALIAS_LDISC(N_R3964);