drivers/tty/n_r3964.c

   1 // SPDX-License-Identifier: GPL-1.0+
   2 /* r3964 linediscipline for linux
   3  *
   4  * -----------------------------------------------------------
   5  * Copyright by
   6  * Philips Automation Projects
   7  * Kassel (Germany)
   8  * -----------------------------------------------------------
   9  * Author:
  10  * L. Haag
  11  *
  12  * $Log: n_r3964.c,v $
  13  * Revision 1.10  2001/03/18 13:02:24  dwmw2
  14  * Fix timer usage, use spinlocks properly.
  15  *
  16  * Revision 1.9  2001/03/18 12:52:14  dwmw2
  17  * Merge changes in 2.4.2
  18  *
  19  * Revision 1.8  2000/03/23 14:14:54  dwmw2
  20  * Fix race in sleeping in r3964_read()
  21  *
  22  * Revision 1.7  1999/28/08 11:41:50  dwmw2
  23  * Port to 2.3 kernel
  24  *
  25  * Revision 1.6  1998/09/30 00:40:40  dwmw2
  26  * Fixed compilation on 2.0.x kernels
  27  * Updated to newly registered tty-ldisc number 9
  28  *
  29  * Revision 1.5  1998/09/04 21:57:36  dwmw2
  30  * Signal handling bug fixes, port to 2.1.x.
  31  *
  32  * Revision 1.4  1998/04/02 20:26:59  lhaag
  33  * select, blocking, ...
  34  *
  35  * Revision 1.3  1998/02/12 18:58:43  root
  36  * fixed some memory leaks
  37  * calculation of checksum characters
  38  *
  39  * Revision 1.2  1998/02/07 13:03:34  root
  40  * ioctl read_telegram
  41  *
  42  * Revision 1.1  1998/02/06 19:21:03  root
  43  * Initial revision
  44  *
  45  *
  46  */
  47
  48 #include <linux/module.h>
  49 #include <linux/kernel.h>
  50 #include <linux/sched.h>
  51 #include <linux/types.h>
  52 #include <linux/fcntl.h>
  53 #include <linux/interrupt.h>
  54 #include <linux/ptrace.h>
  55 #include <linux/ioport.h>
  56 #include <linux/in.h>
  57 #include <linux/slab.h>
  58 #include <linux/tty.h>
  59 #include <linux/errno.h>
  60 #include <linux/string.h>       /* used in new tty drivers */
  61 #include <linux/signal.h>       /* used in new tty drivers */
  62 #include <linux/ioctl.h>
  63 #include <linux/n_r3964.h>
  64 #include <linux/poll.h>
  65 #include <linux/init.h>
  66 #include <linux/uaccess.h>
  67
  68 /*#define DEBUG_QUEUE*/
  69
  70 /* Log successful handshake and protocol operations  */
  71 /*#define DEBUG_PROTO_S*/
  72
  73 /* Log handshake and protocol errors: */
  74 /*#define DEBUG_PROTO_E*/
  75
  76 /* Log Linediscipline operations (open, close, read, write...): */
  77 /*#define DEBUG_LDISC*/
  78
  79 /* Log module and memory operations (init, cleanup; kmalloc, kfree): */
  80 /*#define DEBUG_MODUL*/
  81
  82 /* Macro helpers for debug output: */
  83 #define TRACE(format, args...) printk("r3964: " format "\n" , ## args)
  84
  85 #ifdef DEBUG_MODUL
  86 #define TRACE_M(format, args...) printk("r3964: " format "\n" , ## args)
  87 #else
  88 #define TRACE_M(fmt, arg...) do {} while (0)
  89 #endif
  90 #ifdef DEBUG_PROTO_S
  91 #define TRACE_PS(format, args...) printk("r3964: " format "\n" , ## args)
  92 #else
  93 #define TRACE_PS(fmt, arg...) do {} while (0)
  94 #endif
  95 #ifdef DEBUG_PROTO_E
  96 #define TRACE_PE(format, args...) printk("r3964: " format "\n" , ## args)
  97 #else
  98 #define TRACE_PE(fmt, arg...) do {} while (0)
  99 #endif
 100 #ifdef DEBUG_LDISC
 101 #define TRACE_L(format, args...) printk("r3964: " format "\n" , ## args)
 102 #else
 103 #define TRACE_L(fmt, arg...) do {} while (0)
 104 #endif
 105 #ifdef DEBUG_QUEUE
 106 #define TRACE_Q(format, args...) printk("r3964: " format "\n" , ## args)
 107 #else
 108 #define TRACE_Q(fmt, arg...) do {} while (0)
 109 #endif
 110 static void add_tx_queue(struct r3964_info *, struct r3964_block_header *);
 111 static void remove_from_tx_queue(struct r3964_info *pInfo, int error_code);
 112 static void put_char(struct r3964_info *pInfo, unsigned char ch);
 113 static void trigger_transmit(struct r3964_info *pInfo);
 114 static void retry_transmit(struct r3964_info *pInfo);
 115 static void transmit_block(struct r3964_info *pInfo);
 116 static void receive_char(struct r3964_info *pInfo, const unsigned char c);
 117 static void receive_error(struct r3964_info *pInfo, const char flag);
 118 static void on_timeout(struct timer_list *t);
 119 static int enable_signals(struct r3964_info *pInfo, struct pid *pid, int arg);
 120 static int read_telegram(struct r3964_info *pInfo, struct pid *pid,
 121                 unsigned char __user * buf);
 122 static void add_msg(struct r3964_client_info *pClient, int msg_id, int arg,
 123                 int error_code, struct r3964_block_header *pBlock);
 124 static struct r3964_message *remove_msg(struct r3964_info *pInfo,
 125                 struct r3964_client_info *pClient);
 126 static void remove_client_block(struct r3964_info *pInfo,
 127                 struct r3964_client_info *pClient);
 128
 129 static int r3964_open(struct tty_struct *tty);
 130 static void r3964_close(struct tty_struct *tty);
 131 static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 132                 unsigned char __user * buf, size_t nr);
 133 static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
 134                 const unsigned char *buf, size_t nr);
 135 static int r3964_ioctl(struct tty_struct *tty, struct file *file,
 136                 unsigned int cmd, unsigned long arg);
 137 #ifdef CONFIG_COMPAT
 138 static int r3964_compat_ioctl(struct tty_struct *tty, struct file *file,
 139                 unsigned int cmd, unsigned long arg);
 140 #endif
 141 static void r3964_set_termios(struct tty_struct *tty, struct ktermios *old);
 142 static __poll_t r3964_poll(struct tty_struct *tty, struct file *file,
 143                 struct poll_table_struct *wait);
 144 static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 145                 char *fp, int count);
 146
 147 static struct tty_ldisc_ops tty_ldisc_N_R3964 = {
 148         .owner = THIS_MODULE,
 149         .magic = TTY_LDISC_MAGIC,
 150         .name = "R3964",
 151         .open = r3964_open,
 152         .close = r3964_close,
 153         .read = r3964_read,
 154         .write = r3964_write,
 155         .ioctl = r3964_ioctl,
 156 #ifdef CONFIG_COMPAT
 157         .compat_ioctl = r3964_compat_ioctl,
 158 #endif
 159         .set_termios = r3964_set_termios,
 160         .poll = r3964_poll,
 161         .receive_buf = r3964_receive_buf,
 162 };
 163
 164 static void dump_block(const unsigned char *block, unsigned int length)
 165 {
 166         unsigned int i, j;
 167         char linebuf[16 * 3 + 1];
 168
 169         for (i = 0; i < length; i += 16) {
 170                 for (j = 0; (j < 16) && (j + i < length); j++) {
 171                         sprintf(linebuf + 3 * j, "%02x ", block[i + j]);
 172                 }
 173                 linebuf[3 * j] = '\0';
 174                 TRACE_PS("%s", linebuf);
 175         }
 176 }
 177
 178 /*************************************************************
 179  * Driver initialisation
 180  *************************************************************/
 181
 182 /*************************************************************
 183  * Module support routines
 184  *************************************************************/
 185
 186 static void __exit r3964_exit(void)
 187 {
 188         int status;
 189
 190         TRACE_M("cleanup_module()");
 191
 192         status = tty_unregister_ldisc(N_R3964);
 193
 194         if (status != 0) {
 195                 printk(KERN_ERR "r3964: error unregistering linediscipline: "
 196                                 "%d\n", status);
 197         } else {
 198                 TRACE_L("linediscipline successfully unregistered");
 199         }
 200 }
 201
 202 static int __init r3964_init(void)
 203 {
 204         int status;
 205
 206         printk("r3964: Philips r3964 Driver $Revision: 1.10 $\n");
 207
 208         /*
 209          * Register the tty line discipline
 210          */
 211
 212         status = tty_register_ldisc(N_R3964, &tty_ldisc_N_R3964);
 213         if (status == 0) {
 214                 TRACE_L("line discipline %d registered", N_R3964);
 215                 TRACE_L("flags=%x num=%x", tty_ldisc_N_R3964.flags,
 216                         tty_ldisc_N_R3964.num);
 217                 TRACE_L("open=%p", tty_ldisc_N_R3964.open);
 218                 TRACE_L("tty_ldisc_N_R3964 = %p", &tty_ldisc_N_R3964);
 219         } else {
 220                 printk(KERN_ERR "r3964: error registering line discipline: "
 221                                 "%d\n", status);
 222         }
 223         return status;
 224 }
 225
 226 module_init(r3964_init);
 227 module_exit(r3964_exit);
 228
 229 /*************************************************************
 230  * Protocol implementation routines
 231  *************************************************************/
 232
 233 static void add_tx_queue(struct r3964_info *pInfo,
 234                          struct r3964_block_header *pHeader)
 235 {
 236         unsigned long flags;
 237
 238         spin_lock_irqsave(&pInfo->lock, flags);
 239
 240         pHeader->next = NULL;
 241
 242         if (pInfo->tx_last == NULL) {
 243                 pInfo->tx_first = pInfo->tx_last = pHeader;
 244         } else {
 245                 pInfo->tx_last->next = pHeader;
 246                 pInfo->tx_last = pHeader;
 247         }
 248
 249         spin_unlock_irqrestore(&pInfo->lock, flags);
 250
 251         TRACE_Q("add_tx_queue %p, length %d, tx_first = %p",
 252                 pHeader, pHeader->length, pInfo->tx_first);
 253 }
 254
 255 static void remove_from_tx_queue(struct r3964_info *pInfo, int error_code)
 256 {
 257         struct r3964_block_header *pHeader;
 258         unsigned long flags;
 259 #ifdef DEBUG_QUEUE
 260         struct r3964_block_header *pDump;
 261 #endif
 262
 263         pHeader = pInfo->tx_first;
 264
 265         if (pHeader == NULL)
 266                 return;
 267
 268 #ifdef DEBUG_QUEUE
 269         printk("r3964: remove_from_tx_queue: %p, length %u - ",
 270                 pHeader, pHeader->length);
 271         for (pDump = pHeader; pDump; pDump = pDump->next)
 272                 printk("%p ", pDump);
 273         printk("\n");
 274 #endif
 275
 276         if (pHeader->owner) {
 277                 if (error_code) {
 278                         add_msg(pHeader->owner, R3964_MSG_ACK, 0,
 279                                 error_code, NULL);
 280                 } else {
 281                         add_msg(pHeader->owner, R3964_MSG_ACK, pHeader->length,
 282                                 error_code, NULL);
 283                 }
 284                 wake_up_interruptible(&pInfo->tty->read_wait);
 285         }
 286
 287         spin_lock_irqsave(&pInfo->lock, flags);
 288
 289         pInfo->tx_first = pHeader->next;
 290         if (pInfo->tx_first == NULL) {
 291                 pInfo->tx_last = NULL;
 292         }
 293
 294         spin_unlock_irqrestore(&pInfo->lock, flags);
 295
 296         kfree(pHeader);
 297         TRACE_M("remove_from_tx_queue - kfree %p", pHeader);
 298
 299         TRACE_Q("remove_from_tx_queue: tx_first = %p, tx_last = %p",
 300                 pInfo->tx_first, pInfo->tx_last);
 301 }
 302
 303 static void add_rx_queue(struct r3964_info *pInfo,
 304                          struct r3964_block_header *pHeader)
 305 {
 306         unsigned long flags;
 307
 308         spin_lock_irqsave(&pInfo->lock, flags);
 309
 310         pHeader->next = NULL;
 311
 312         if (pInfo->rx_last == NULL) {
 313                 pInfo->rx_first = pInfo->rx_last = pHeader;
 314         } else {
 315                 pInfo->rx_last->next = pHeader;
 316                 pInfo->rx_last = pHeader;
 317         }
 318         pInfo->blocks_in_rx_queue++;
 319
 320         spin_unlock_irqrestore(&pInfo->lock, flags);
 321
 322         TRACE_Q("add_rx_queue: %p, length = %d, rx_first = %p, count = %d",
 323                 pHeader, pHeader->length,
 324                 pInfo->rx_first, pInfo->blocks_in_rx_queue);
 325 }
 326
 327 static void remove_from_rx_queue(struct r3964_info *pInfo,
 328                                  struct r3964_block_header *pHeader)
 329 {
 330         unsigned long flags;
 331         struct r3964_block_header *pFind;
 332
 333         if (pHeader == NULL)
 334                 return;
 335
 336         TRACE_Q("remove_from_rx_queue: rx_first = %p, rx_last = %p, count = %d",
 337                 pInfo->rx_first, pInfo->rx_last, pInfo->blocks_in_rx_queue);
 338         TRACE_Q("remove_from_rx_queue: %p, length %u",
 339                 pHeader, pHeader->length);
 340
 341         spin_lock_irqsave(&pInfo->lock, flags);
 342
 343         if (pInfo->rx_first == pHeader) {
 344                 /* Remove the first block in the linked list: */
 345                 pInfo->rx_first = pHeader->next;
 346
 347                 if (pInfo->rx_first == NULL) {
 348                         pInfo->rx_last = NULL;
 349                 }
 350                 pInfo->blocks_in_rx_queue--;
 351         } else {
 352                 /* Find block to remove: */
 353                 for (pFind = pInfo->rx_first; pFind; pFind = pFind->next) {
 354                         if (pFind->next == pHeader) {
 355                                 /* Got it. */
 356                                 pFind->next = pHeader->next;
 357                                 pInfo->blocks_in_rx_queue--;
 358                                 if (pFind->next == NULL) {
 359                                         /* Oh, removed the last one! */
 360                                         pInfo->rx_last = pFind;
 361                                 }
 362                                 break;
 363                         }
 364                 }
 365         }
 366
 367         spin_unlock_irqrestore(&pInfo->lock, flags);
 368
 369         kfree(pHeader);
 370         TRACE_M("remove_from_rx_queue - kfree %p", pHeader);
 371
 372         TRACE_Q("remove_from_rx_queue: rx_first = %p, rx_last = %p, count = %d",
 373                 pInfo->rx_first, pInfo->rx_last, pInfo->blocks_in_rx_queue);
 374 }
 375
 376 static void put_char(struct r3964_info *pInfo, unsigned char ch)
 377 {
 378         struct tty_struct *tty = pInfo->tty;
 379         /* FIXME: put_char should not be called from an IRQ */
 380         tty_put_char(tty, ch);
 381         pInfo->bcc ^= ch;
 382 }
 383
 384 static void flush(struct r3964_info *pInfo)
 385 {
 386         struct tty_struct *tty = pInfo->tty;
 387
 388         if (tty == NULL || tty->ops->flush_chars == NULL)
 389                 return;
 390         tty->ops->flush_chars(tty);
 391 }
 392
 393 static void trigger_transmit(struct r3964_info *pInfo)
 394 {
 395         unsigned long flags;
 396
 397         spin_lock_irqsave(&pInfo->lock, flags);
 398
 399         if ((pInfo->state == R3964_IDLE) && (pInfo->tx_first != NULL)) {
 400                 pInfo->state = R3964_TX_REQUEST;
 401                 pInfo->nRetry = 0;
 402                 pInfo->flags &= ~R3964_ERROR;
 403                 mod_timer(&pInfo->tmr, jiffies + R3964_TO_QVZ);
 404
 405                 spin_unlock_irqrestore(&pInfo->lock, flags);
 406
 407                 TRACE_PS("trigger_transmit - sent STX");
 408
 409                 put_char(pInfo, STX);
 410                 flush(pInfo);
 411
 412                 pInfo->bcc = 0;
 413         } else {
 414                 spin_unlock_irqrestore(&pInfo->lock, flags);
 415         }
 416 }
 417
 418 static void retry_transmit(struct r3964_info *pInfo)
 419 {
 420         if (pInfo->nRetry < R3964_MAX_RETRIES) {
 421                 TRACE_PE("transmission failed. Retry #%d", pInfo->nRetry);
 422                 pInfo->bcc = 0;
 423                 put_char(pInfo, STX);
 424                 flush(pInfo);
 425                 pInfo->state = R3964_TX_REQUEST;
 426                 pInfo->nRetry++;
 427                 mod_timer(&pInfo->tmr, jiffies + R3964_TO_QVZ);
 428         } else {
 429                 TRACE_PE("transmission failed after %d retries",
 430                          R3964_MAX_RETRIES);
 431
 432                 remove_from_tx_queue(pInfo, R3964_TX_FAIL);
 433
 434                 put_char(pInfo, NAK);
 435                 flush(pInfo);
 436                 pInfo->state = R3964_IDLE;
 437
 438                 trigger_transmit(pInfo);
 439         }
 440 }
 441
 442 static void transmit_block(struct r3964_info *pInfo)
 443 {
 444         struct tty_struct *tty = pInfo->tty;
 445         struct r3964_block_header *pBlock = pInfo->tx_first;
 446         int room = 0;
 447
 448         if (tty == NULL || pBlock == NULL) {
 449                 return;
 450         }
 451
 452         room = tty_write_room(tty);
 453
 454         TRACE_PS("transmit_block %p, room %d, length %d",
 455                  pBlock, room, pBlock->length);
 456
 457         while (pInfo->tx_position < pBlock->length) {
 458                 if (room < 2)
 459                         break;
 460
 461                 if (pBlock->data[pInfo->tx_position] == DLE) {
 462                         /* send additional DLE char: */
 463                         put_char(pInfo, DLE);
 464                 }
 465                 put_char(pInfo, pBlock->data[pInfo->tx_position++]);
 466
 467                 room--;
 468         }
 469
 470         if ((pInfo->tx_position == pBlock->length) && (room >= 3)) {
 471                 put_char(pInfo, DLE);
 472                 put_char(pInfo, ETX);
 473                 if (pInfo->flags & R3964_BCC) {
 474                         put_char(pInfo, pInfo->bcc);
 475                 }
 476                 pInfo->state = R3964_WAIT_FOR_TX_ACK;
 477                 mod_timer(&pInfo->tmr, jiffies + R3964_TO_QVZ);
 478         }
 479         flush(pInfo);
 480 }
 481
 482 static void on_receive_block(struct r3964_info *pInfo)
 483 {
 484         unsigned int length;
 485         struct r3964_client_info *pClient;
 486         struct r3964_block_header *pBlock;
 487
 488         length = pInfo->rx_position;
 489
 490         /* compare byte checksum characters: */
 491         if (pInfo->flags & R3964_BCC) {
 492                 if (pInfo->bcc != pInfo->last_rx) {
 493                         TRACE_PE("checksum error - got %x but expected %x",
 494                                  pInfo->last_rx, pInfo->bcc);
 495                         pInfo->flags |= R3964_CHECKSUM;
 496                 }
 497         }
 498
 499         /* check for errors (parity, overrun,...): */
 500         if (pInfo->flags & R3964_ERROR) {
 501                 TRACE_PE("on_receive_block - transmission failed error %x",
 502                          pInfo->flags & R3964_ERROR);
 503
 504                 put_char(pInfo, NAK);
 505                 flush(pInfo);
 506                 if (pInfo->nRetry < R3964_MAX_RETRIES) {
 507                         pInfo->state = R3964_WAIT_FOR_RX_REPEAT;
 508                         pInfo->nRetry++;
 509                         mod_timer(&pInfo->tmr, jiffies + R3964_TO_RX_PANIC);
 510                 } else {
 511                         TRACE_PE("on_receive_block - failed after max retries");
 512                         pInfo->state = R3964_IDLE;
 513                 }
 514                 return;
 515         }
 516
 517         /* received block; submit DLE: */
 518         put_char(pInfo, DLE);
 519         flush(pInfo);
 520         del_timer_sync(&pInfo->tmr);
 521         TRACE_PS(" rx success: got %d chars", length);
 522
 523         /* prepare struct r3964_block_header: */
 524         pBlock = kmalloc(length + sizeof(struct r3964_block_header),
 525                         GFP_KERNEL);
 526         TRACE_M("on_receive_block - kmalloc %p", pBlock);
 527
 528         if (pBlock == NULL)
 529                 return;
 530
 531         pBlock->length = length;
 532         pBlock->data = ((unsigned char *)pBlock) +
 533                         sizeof(struct r3964_block_header);
 534         pBlock->locks = 0;
 535         pBlock->next = NULL;
 536         pBlock->owner = NULL;
 537
 538         memcpy(pBlock->data, pInfo->rx_buf, length);
 539
 540         /* queue block into rx_queue: */
 541         add_rx_queue(pInfo, pBlock);
 542
 543         /* notify attached client processes: */
 544         for (pClient = pInfo->firstClient; pClient; pClient = pClient->next) {
 545                 if (pClient->sig_flags & R3964_SIG_DATA) {
 546                         add_msg(pClient, R3964_MSG_DATA, length, R3964_OK,
 547                                 pBlock);
 548                 }
 549         }
 550         wake_up_interruptible(&pInfo->tty->read_wait);
 551
 552         pInfo->state = R3964_IDLE;
 553
 554         trigger_transmit(pInfo);
 555 }
 556
 557 static void receive_char(struct r3964_info *pInfo, const unsigned char c)
 558 {
 559         switch (pInfo->state) {
 560         case R3964_TX_REQUEST:
 561                 if (c == DLE) {
 562                         TRACE_PS("TX_REQUEST - got DLE");
 563
 564                         pInfo->state = R3964_TRANSMITTING;
 565                         pInfo->tx_position = 0;
 566
 567                         transmit_block(pInfo);
 568                 } else if (c == STX) {
 569                         if (pInfo->nRetry == 0) {
 570                                 TRACE_PE("TX_REQUEST - init conflict");
 571                                 if (pInfo->priority == R3964_SLAVE) {
 572                                         goto start_receiving;
 573                                 }
 574                         } else {
 575                                 TRACE_PE("TX_REQUEST - secondary init "
 576                                         "conflict!? Switching to SLAVE mode "
 577                                         "for next rx.");
 578                                 goto start_receiving;
 579                         }
 580                 } else {
 581                         TRACE_PE("TX_REQUEST - char != DLE: %x", c);
 582                         retry_transmit(pInfo);
 583                 }
 584                 break;
 585         case R3964_TRANSMITTING:
 586                 if (c == NAK) {
 587                         TRACE_PE("TRANSMITTING - got NAK");
 588                         retry_transmit(pInfo);
 589                 } else {
 590                         TRACE_PE("TRANSMITTING - got invalid char");
 591
 592                         pInfo->state = R3964_WAIT_ZVZ_BEFORE_TX_RETRY;
 593                         mod_timer(&pInfo->tmr, jiffies + R3964_TO_ZVZ);
 594                 }
 595                 break;
 596         case R3964_WAIT_FOR_TX_ACK:
 597                 if (c == DLE) {
 598                         TRACE_PS("WAIT_FOR_TX_ACK - got DLE");
 599                         remove_from_tx_queue(pInfo, R3964_OK);
 600
 601                         pInfo->state = R3964_IDLE;
 602                         trigger_transmit(pInfo);
 603                 } else {
 604                         retry_transmit(pInfo);
 605                 }
 606                 break;
 607         case R3964_WAIT_FOR_RX_REPEAT:
 608                 /* FALLTHROUGH */
 609         case R3964_IDLE:
 610                 if (c == STX) {
 611                         /* Prevent rx_queue from overflow: */
 612                         if (pInfo->blocks_in_rx_queue >=
 613                             R3964_MAX_BLOCKS_IN_RX_QUEUE) {
 614                                 TRACE_PE("IDLE - got STX but no space in "
 615                                                 "rx_queue!");
 616                                 pInfo->state = R3964_WAIT_FOR_RX_BUF;
 617                                 mod_timer(&pInfo->tmr,
 618                                           jiffies + R3964_TO_NO_BUF);
 619                                 break;
 620                         }
 621 start_receiving:
 622                         /* Ok, start receiving: */
 623                         TRACE_PS("IDLE - got STX");
 624                         pInfo->rx_position = 0;
 625                         pInfo->last_rx = 0;
 626                         pInfo->flags &= ~R3964_ERROR;
 627                         pInfo->state = R3964_RECEIVING;
 628                         mod_timer(&pInfo->tmr, jiffies + R3964_TO_ZVZ);
 629                         pInfo->nRetry = 0;
 630                         put_char(pInfo, DLE);
 631                         flush(pInfo);
 632                         pInfo->bcc = 0;
 633                 }
 634                 break;
 635         case R3964_RECEIVING:
 636                 if (pInfo->rx_position < RX_BUF_SIZE) {
 637                         pInfo->bcc ^= c;
 638
 639                         if (c == DLE) {
 640                                 if (pInfo->last_rx == DLE) {
 641                                         pInfo->last_rx = 0;
 642                                         goto char_to_buf;
 643                                 }
 644                                 pInfo->last_rx = DLE;
 645                                 break;
 646                         } else if ((c == ETX) && (pInfo->last_rx == DLE)) {
 647                                 if (pInfo->flags & R3964_BCC) {
 648                                         pInfo->state = R3964_WAIT_FOR_BCC;
 649                                         mod_timer(&pInfo->tmr,
 650                                                   jiffies + R3964_TO_ZVZ);
 651                                 } else {
 652                                         on_receive_block(pInfo);
 653                                 }
 654                         } else {
 655                                 pInfo->last_rx = c;
 656 char_to_buf:
 657                                 pInfo->rx_buf[pInfo->rx_position++] = c;
 658                                 mod_timer(&pInfo->tmr, jiffies + R3964_TO_ZVZ);
 659                         }
 660                 }
 661                 /* else: overflow-msg? BUF_SIZE>MTU; should not happen? */
 662                 break;
 663         case R3964_WAIT_FOR_BCC:
 664                 pInfo->last_rx = c;
 665                 on_receive_block(pInfo);
 666                 break;
 667         }
 668 }
 669
 670 static void receive_error(struct r3964_info *pInfo, const char flag)
 671 {
 672         switch (flag) {
 673         case TTY_NORMAL:
 674                 break;
 675         case TTY_BREAK:
 676                 TRACE_PE("received break");
 677                 pInfo->flags |= R3964_BREAK;
 678                 break;
 679         case TTY_PARITY:
 680                 TRACE_PE("parity error");
 681                 pInfo->flags |= R3964_PARITY;
 682                 break;
 683         case TTY_FRAME:
 684                 TRACE_PE("frame error");
 685                 pInfo->flags |= R3964_FRAME;
 686                 break;
 687         case TTY_OVERRUN:
 688                 TRACE_PE("frame overrun");
 689                 pInfo->flags |= R3964_OVERRUN;
 690                 break;
 691         default:
 692                 TRACE_PE("receive_error - unknown flag %d", flag);
 693                 pInfo->flags |= R3964_UNKNOWN;
 694                 break;
 695         }
 696 }
 697
 698 static void on_timeout(struct timer_list *t)
 699 {
 700         struct r3964_info *pInfo = from_timer(pInfo, t, tmr);
 701
 702         switch (pInfo->state) {
 703         case R3964_TX_REQUEST:
 704                 TRACE_PE("TX_REQUEST - timeout");
 705                 retry_transmit(pInfo);
 706                 break;
 707         case R3964_WAIT_ZVZ_BEFORE_TX_RETRY:
 708                 put_char(pInfo, NAK);
 709                 flush(pInfo);
 710                 retry_transmit(pInfo);
 711                 break;
 712         case R3964_WAIT_FOR_TX_ACK:
 713                 TRACE_PE("WAIT_FOR_TX_ACK - timeout");
 714                 retry_transmit(pInfo);
 715                 break;
 716         case R3964_WAIT_FOR_RX_BUF:
 717                 TRACE_PE("WAIT_FOR_RX_BUF - timeout");
 718                 put_char(pInfo, NAK);
 719                 flush(pInfo);
 720                 pInfo->state = R3964_IDLE;
 721                 break;
 722         case R3964_RECEIVING:
 723                 TRACE_PE("RECEIVING - timeout after %d chars",
 724                          pInfo->rx_position);
 725                 put_char(pInfo, NAK);
 726                 flush(pInfo);
 727                 pInfo->state = R3964_IDLE;
 728                 break;
 729         case R3964_WAIT_FOR_RX_REPEAT:
 730                 TRACE_PE("WAIT_FOR_RX_REPEAT - timeout");
 731                 pInfo->state = R3964_IDLE;
 732                 break;
 733         case R3964_WAIT_FOR_BCC:
 734                 TRACE_PE("WAIT_FOR_BCC - timeout");
 735                 put_char(pInfo, NAK);
 736                 flush(pInfo);
 737                 pInfo->state = R3964_IDLE;
 738                 break;
 739         }
 740 }
 741
 742 static struct r3964_client_info *findClient(struct r3964_info *pInfo,
 743                 struct pid *pid)
 744 {
 745         struct r3964_client_info *pClient;
 746
 747         for (pClient = pInfo->firstClient; pClient; pClient = pClient->next) {
 748                 if (pClient->pid == pid) {
 749                         return pClient;
 750                 }
 751         }
 752         return NULL;
 753 }
 754
 755 static int enable_signals(struct r3964_info *pInfo, struct pid *pid, int arg)
 756 {
 757         struct r3964_client_info *pClient;
 758         struct r3964_client_info **ppClient;
 759         struct r3964_message *pMsg;
 760
 761         if ((arg & R3964_SIG_ALL) == 0) {
 762                 /* Remove client from client list */
 763                 for (ppClient = &pInfo->firstClient; *ppClient;
 764                      ppClient = &(*ppClient)->next) {
 765                         pClient = *ppClient;
 766
 767                         if (pClient->pid == pid) {
 768                                 TRACE_PS("removing client %d from client list",
 769                                          pid_nr(pid));
 770                                 *ppClient = pClient->next;
 771                                 while (pClient->msg_count) {
 772                                         pMsg = remove_msg(pInfo, pClient);
 773                                         if (pMsg) {
 774                                                 kfree(pMsg);
 775                                                 TRACE_M("enable_signals - msg "
 776                                                         "kfree %p", pMsg);
 777                                         }
 778                                 }
 779                                 put_pid(pClient->pid);
 780                                 kfree(pClient);
 781                                 TRACE_M("enable_signals - kfree %p", pClient);
 782                                 return 0;
 783                         }
 784                 }
 785                 return -EINVAL;
 786         } else {
 787                 pClient = findClient(pInfo, pid);
 788                 if (pClient) {
 789                         /* update signal options */
 790                         pClient->sig_flags = arg;
 791                 } else {
 792                         /* add client to client list */
 793                         pClient = kmalloc(sizeof(struct r3964_client_info),
 794                                         GFP_KERNEL);
 795                         TRACE_M("enable_signals - kmalloc %p", pClient);
 796                         if (pClient == NULL)
 797                                 return -ENOMEM;
 798
 799                         TRACE_PS("add client %d to client list", pid_nr(pid));
 800                         spin_lock_init(&pClient->lock);
 801                         pClient->sig_flags = arg;
 802                         pClient->pid = get_pid(pid);
 803                         pClient->next = pInfo->firstClient;
 804                         pClient->first_msg = NULL;
 805                         pClient->last_msg = NULL;
 806                         pClient->next_block_to_read = NULL;
 807                         pClient->msg_count = 0;
 808                         pInfo->firstClient = pClient;
 809                 }
 810         }
 811
 812         return 0;
 813 }
 814
 815 static int read_telegram(struct r3964_info *pInfo, struct pid *pid,
 816                          unsigned char __user * buf)
 817 {
 818         struct r3964_client_info *pClient;
 819         struct r3964_block_header *block;
 820
 821         if (!buf) {
 822                 return -EINVAL;
 823         }
 824
 825         pClient = findClient(pInfo, pid);
 826         if (pClient == NULL) {
 827                 return -EINVAL;
 828         }
 829
 830         block = pClient->next_block_to_read;
 831         if (!block) {
 832                 return 0;
 833         } else {
 834                 if (copy_to_user(buf, block->data, block->length))
 835                         return -EFAULT;
 836
 837                 remove_client_block(pInfo, pClient);
 838                 return block->length;
 839         }
 840
 841         return -EINVAL;
 842 }
 843
 844 static void add_msg(struct r3964_client_info *pClient, int msg_id, int arg,
 845                 int error_code, struct r3964_block_header *pBlock)
 846 {
 847         struct r3964_message *pMsg;
 848         unsigned long flags;
 849
 850         if (pClient->msg_count < R3964_MAX_MSG_COUNT - 1) {
 851 queue_the_message:
 852
 853                 pMsg = kmalloc(sizeof(struct r3964_message),
 854                                 error_code ? GFP_ATOMIC : GFP_KERNEL);
 855                 TRACE_M("add_msg - kmalloc %p", pMsg);
 856                 if (pMsg == NULL) {
 857                         return;
 858                 }
 859
 860                 spin_lock_irqsave(&pClient->lock, flags);
 861
 862                 pMsg->msg_id = msg_id;
 863                 pMsg->arg = arg;
 864                 pMsg->error_code = error_code;
 865                 pMsg->block = pBlock;
 866                 pMsg->next = NULL;
 867
 868                 if (pClient->last_msg == NULL) {
 869                         pClient->first_msg = pClient->last_msg = pMsg;
 870                 } else {
 871                         pClient->last_msg->next = pMsg;
 872                         pClient->last_msg = pMsg;
 873                 }
 874
 875                 pClient->msg_count++;
 876
 877                 if (pBlock != NULL) {
 878                         pBlock->locks++;
 879                 }
 880                 spin_unlock_irqrestore(&pClient->lock, flags);
 881         } else {
 882                 if ((pClient->last_msg->msg_id == R3964_MSG_ACK)
 883                     && (pClient->last_msg->error_code == R3964_OVERFLOW)) {
 884                         pClient->last_msg->arg++;
 885                         TRACE_PE("add_msg - inc prev OVERFLOW-msg");
 886                 } else {
 887                         msg_id = R3964_MSG_ACK;
 888                         arg = 0;
 889                         error_code = R3964_OVERFLOW;
 890                         pBlock = NULL;
 891                         TRACE_PE("add_msg - queue OVERFLOW-msg");
 892                         goto queue_the_message;
 893                 }
 894         }
 895         /* Send SIGIO signal to client process: */
 896         if (pClient->sig_flags & R3964_USE_SIGIO) {
 897                 kill_pid(pClient->pid, SIGIO, 1);
 898         }
 899 }
 900
 901 static struct r3964_message *remove_msg(struct r3964_info *pInfo,
 902                                         struct r3964_client_info *pClient)
 903 {
 904         struct r3964_message *pMsg = NULL;
 905         unsigned long flags;
 906
 907         if (pClient->first_msg) {
 908                 spin_lock_irqsave(&pClient->lock, flags);
 909
 910                 pMsg = pClient->first_msg;
 911                 pClient->first_msg = pMsg->next;
 912                 if (pClient->first_msg == NULL) {
 913                         pClient->last_msg = NULL;
 914                 }
 915
 916                 pClient->msg_count--;
 917                 if (pMsg->block) {
 918                         remove_client_block(pInfo, pClient);
 919                         pClient->next_block_to_read = pMsg->block;
 920                 }
 921                 spin_unlock_irqrestore(&pClient->lock, flags);
 922         }
 923         return pMsg;
 924 }
 925
 926 static void remove_client_block(struct r3964_info *pInfo,
 927                                 struct r3964_client_info *pClient)
 928 {
 929         struct r3964_block_header *block;
 930
 931         TRACE_PS("remove_client_block PID %d", pid_nr(pClient->pid));
 932
 933         block = pClient->next_block_to_read;
 934         if (block) {
 935                 block->locks--;
 936                 if (block->locks == 0) {
 937                         remove_from_rx_queue(pInfo, block);
 938                 }
 939         }
 940         pClient->next_block_to_read = NULL;
 941 }
 942
 943 /*************************************************************
 944  * Line discipline routines
 945  *************************************************************/
 946
 947 static int r3964_open(struct tty_struct *tty)
 948 {
 949         struct r3964_info *pInfo;
 950
 951         TRACE_L("open");
 952         TRACE_L("tty=%p, PID=%d, disc_data=%p",
 953                 tty, current->pid, tty->disc_data);
 954
 955         pInfo = kmalloc(sizeof(struct r3964_info), GFP_KERNEL);
 956         TRACE_M("r3964_open - info kmalloc %p", pInfo);
 957
 958         if (!pInfo) {
 959                 printk(KERN_ERR "r3964: failed to alloc info structure\n");
 960                 return -ENOMEM;
 961         }
 962
 963         pInfo->rx_buf = kmalloc(RX_BUF_SIZE, GFP_KERNEL);
 964         TRACE_M("r3964_open - rx_buf kmalloc %p", pInfo->rx_buf);
 965
 966         if (!pInfo->rx_buf) {
 967                 printk(KERN_ERR "r3964: failed to alloc receive buffer\n");
 968                 kfree(pInfo);
 969                 TRACE_M("r3964_open - info kfree %p", pInfo);
 970                 return -ENOMEM;
 971         }
 972
 973         pInfo->tx_buf = kmalloc(TX_BUF_SIZE, GFP_KERNEL);
 974         TRACE_M("r3964_open - tx_buf kmalloc %p", pInfo->tx_buf);
 975
 976         if (!pInfo->tx_buf) {
 977                 printk(KERN_ERR "r3964: failed to alloc transmit buffer\n");
 978                 kfree(pInfo->rx_buf);
 979                 TRACE_M("r3964_open - rx_buf kfree %p", pInfo->rx_buf);
 980                 kfree(pInfo);
 981                 TRACE_M("r3964_open - info kfree %p", pInfo);
 982                 return -ENOMEM;
 983         }
 984
 985         spin_lock_init(&pInfo->lock);
 986         mutex_init(&pInfo->read_lock);
 987         pInfo->tty = tty;
 988         pInfo->priority = R3964_MASTER;
 989         pInfo->rx_first = pInfo->rx_last = NULL;
 990         pInfo->tx_first = pInfo->tx_last = NULL;
 991         pInfo->rx_position = 0;
 992         pInfo->tx_position = 0;
 993         pInfo->last_rx = 0;
 994         pInfo->blocks_in_rx_queue = 0;
 995         pInfo->firstClient = NULL;
 996         pInfo->state = R3964_IDLE;
 997         pInfo->flags = R3964_DEBUG;
 998         pInfo->nRetry = 0;
 999
1000         tty->disc_data = pInfo;
1001         tty->receive_room = 65536;
1002
1003         timer_setup(&pInfo->tmr, on_timeout, 0);
1004
1005         return 0;
1006 }
1007
1008 static void r3964_close(struct tty_struct *tty)
1009 {
1010         struct r3964_info *pInfo = tty->disc_data;
1011         struct r3964_client_info *pClient, *pNext;
1012         struct r3964_message *pMsg;
1013         struct r3964_block_header *pHeader, *pNextHeader;
1014         unsigned long flags;
1015
1016         TRACE_L("close");
1017
1018         /*
1019          * Make sure that our task queue isn't activated.  If it
1020          * is, take it out of the linked list.
1021          */
1022         del_timer_sync(&pInfo->tmr);
1023
1024         /* Remove client-structs and message queues: */
1025         pClient = pInfo->firstClient;
1026         while (pClient) {
1027                 pNext = pClient->next;
1028                 while (pClient->msg_count) {
1029                         pMsg = remove_msg(pInfo, pClient);
1030                         if (pMsg) {
1031                                 kfree(pMsg);
1032                                 TRACE_M("r3964_close - msg kfree %p", pMsg);
1033                         }
1034                 }
1035                 put_pid(pClient->pid);
1036                 kfree(pClient);
1037                 TRACE_M("r3964_close - client kfree %p", pClient);
1038                 pClient = pNext;
1039         }
1040         /* Remove jobs from tx_queue: */
1041         spin_lock_irqsave(&pInfo->lock, flags);
1042         pHeader = pInfo->tx_first;
1043         pInfo->tx_first = pInfo->tx_last = NULL;
1044         spin_unlock_irqrestore(&pInfo->lock, flags);
1045
1046         while (pHeader) {
1047                 pNextHeader = pHeader->next;
1048                 kfree(pHeader);
1049                 pHeader = pNextHeader;
1050         }
1051
1052         /* Free buffers: */
1053         kfree(pInfo->rx_buf);
1054         TRACE_M("r3964_close - rx_buf kfree %p", pInfo->rx_buf);
1055         kfree(pInfo->tx_buf);
1056         TRACE_M("r3964_close - tx_buf kfree %p", pInfo->tx_buf);
1057         kfree(pInfo);
1058         TRACE_M("r3964_close - info kfree %p", pInfo);
1059 }
1060
1061 static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
1062                           unsigned char __user * buf, size_t nr)
1063 {
1064         struct r3964_info *pInfo = tty->disc_data;
1065         struct r3964_client_info *pClient;
1066         struct r3964_message *pMsg;
1067         struct r3964_client_message theMsg;
1068         int ret;
1069
1070         TRACE_L("read()");
1071
1072         /*
1073          *      Internal serialization of reads.
1074          */
1075         if (file->f_flags & O_NONBLOCK) {
1076                 if (!mutex_trylock(&pInfo->read_lock))
1077                         return -EAGAIN;
1078         } else {
1079                 if (mutex_lock_interruptible(&pInfo->read_lock))
1080                         return -ERESTARTSYS;
1081         }
1082
1083         pClient = findClient(pInfo, task_pid(current));
1084         if (pClient) {
1085                 pMsg = remove_msg(pInfo, pClient);
1086                 if (pMsg == NULL) {
1087                         /* no messages available. */
1088                         if (file->f_flags & O_NONBLOCK) {
1089                                 ret = -EAGAIN;
1090                                 goto unlock;
1091                         }
1092                         /* block until there is a message: */
1093                         wait_event_interruptible(tty->read_wait,
1094                                         (pMsg = remove_msg(pInfo, pClient)));
1095                 }
1096
1097                 /* If we still haven't got a message, we must have been signalled */
1098
1099                 if (!pMsg) {
1100                         ret = -EINTR;
1101                         goto unlock;
1102                 }
1103
1104                 /* deliver msg to client process: */
1105                 theMsg.msg_id = pMsg->msg_id;
1106                 theMsg.arg = pMsg->arg;
1107                 theMsg.error_code = pMsg->error_code;
1108                 ret = sizeof(struct r3964_client_message);
1109
1110                 kfree(pMsg);
1111                 TRACE_M("r3964_read - msg kfree %p", pMsg);
1112
1113                 if (copy_to_user(buf, &theMsg, ret)) {
1114                         ret = -EFAULT;
1115                         goto unlock;
1116                 }
1117
1118                 TRACE_PS("read - return %d", ret);
1119                 goto unlock;
1120         }
1121         ret = -EPERM;
1122 unlock:
1123         mutex_unlock(&pInfo->read_lock);
1124         return ret;
1125 }
1126
1127 static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
1128                            const unsigned char *data, size_t count)
1129 {
1130         struct r3964_info *pInfo = tty->disc_data;
1131         struct r3964_block_header *pHeader;
1132         struct r3964_client_info *pClient;
1133         unsigned char *new_data;
1134
1135         TRACE_L("write request, %d characters", count);
1136 /*
1137  * Verify the pointers
1138  */
1139
1140         if (!pInfo)
1141                 return -EIO;
1142
1143 /*
1144  * Ensure that the caller does not wish to send too much.
1145  */
1146         if (count > R3964_MTU) {
1147                 if (pInfo->flags & R3964_DEBUG) {
1148                         TRACE_L(KERN_WARNING "r3964_write: truncating user "
1149                                 "packet from %u to mtu %d", count, R3964_MTU);
1150                 }
1151                 count = R3964_MTU;
1152         }
1153 /*
1154  * Allocate a buffer for the data and copy it from the buffer with header prepended
1155  */
1156         new_data = kmalloc(count + sizeof(struct r3964_block_header),
1157                         GFP_KERNEL);
1158         TRACE_M("r3964_write - kmalloc %p", new_data);
1159         if (new_data == NULL) {
1160                 if (pInfo->flags & R3964_DEBUG) {
1161                         printk(KERN_ERR "r3964_write: no memory\n");
1162                 }
1163                 return -ENOSPC;
1164         }
1165
1166         pHeader = (struct r3964_block_header *)new_data;
1167         pHeader->data = new_data + sizeof(struct r3964_block_header);
1168         pHeader->length = count;
1169         pHeader->locks = 0;
1170         pHeader->owner = NULL;
1171
1172         pClient = findClient(pInfo, task_pid(current));
1173         if (pClient) {
1174                 pHeader->owner = pClient;
1175         }
1176
1177         memcpy(pHeader->data, data, count);     /* We already verified this */
1178
1179         if (pInfo->flags & R3964_DEBUG) {
1180                 dump_block(pHeader->data, count);
1181         }
1182
1183 /*
1184  * Add buffer to transmit-queue:
1185  */
1186         add_tx_queue(pInfo, pHeader);
1187         trigger_transmit(pInfo);
1188
1189         return 0;
1190 }
1191
1192 static int r3964_ioctl(struct tty_struct *tty, struct file *file,
1193                 unsigned int cmd, unsigned long arg)
1194 {
1195         struct r3964_info *pInfo = tty->disc_data;
1196         if (pInfo == NULL)
1197                 return -EINVAL;
1198         switch (cmd) {
1199         case R3964_ENABLE_SIGNALS:
1200                 return enable_signals(pInfo, task_pid(current), arg);
1201         case R3964_SETPRIORITY:
1202                 if (arg < R3964_MASTER || arg > R3964_SLAVE)
1203                         return -EINVAL;
1204                 pInfo->priority = arg & 0xff;
1205                 return 0;
1206         case R3964_USE_BCC:
1207                 if (arg)
1208                         pInfo->flags |= R3964_BCC;
1209                 else
1210                         pInfo->flags &= ~R3964_BCC;
1211                 return 0;
1212         case R3964_READ_TELEGRAM:
1213                 return read_telegram(pInfo, task_pid(current),
1214                                 (unsigned char __user *)arg);
1215         default:
1216                 return -ENOIOCTLCMD;
1217         }
1218 }
1219
1220 #ifdef CONFIG_COMPAT
1221 static int r3964_compat_ioctl(struct tty_struct *tty, struct file *file,
1222                 unsigned int cmd, unsigned long arg)
1223 {
1224         switch (cmd) {
1225         case R3964_ENABLE_SIGNALS:
1226         case R3964_SETPRIORITY:
1227         case R3964_USE_BCC:
1228                 return r3964_ioctl(tty, file, cmd, arg);
1229         default:
1230                 return -ENOIOCTLCMD;
1231         }
1232 }
1233 #endif
1234
1235 static void r3964_set_termios(struct tty_struct *tty, struct ktermios *old)
1236 {
1237         TRACE_L("set_termios");
1238 }
1239
1240 /* Called without the kernel lock held - fine */
1241 static __poll_t r3964_poll(struct tty_struct *tty, struct file *file,
1242                         struct poll_table_struct *wait)
1243 {
1244         struct r3964_info *pInfo = tty->disc_data;
1245         struct r3964_client_info *pClient;
1246         struct r3964_message *pMsg = NULL;
1247         unsigned long flags;
1248         __poll_t result = EPOLLOUT;
1249
1250         TRACE_L("POLL");
1251
1252         pClient = findClient(pInfo, task_pid(current));
1253         if (pClient) {
1254                 poll_wait(file, &tty->read_wait, wait);
1255                 spin_lock_irqsave(&pInfo->lock, flags);
1256                 pMsg = pClient->first_msg;
1257                 spin_unlock_irqrestore(&pInfo->lock, flags);
1258                 if (pMsg)
1259                         result |= EPOLLIN | EPOLLRDNORM;
1260         } else {
1261                 result = -EINVAL;
1262         }
1263         return result;
1264 }
1265
1266 static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1267                         char *fp, int count)
1268 {
1269         struct r3964_info *pInfo = tty->disc_data;
1270         const unsigned char *p;
1271         char *f, flags = TTY_NORMAL;
1272         int i;
1273
1274         for (i = count, p = cp, f = fp; i; i--, p++) {
1275                 if (f)
1276                         flags = *f++;
1277                 if (flags == TTY_NORMAL) {
1278                         receive_char(pInfo, *p);
1279                 } else {
1280                         receive_error(pInfo, flags);
1281                 }
1282
1283         }
1284 }
1285
1286 MODULE_LICENSE("GPL");
1287 MODULE_ALIAS_LDISC(N_R3964);