drivers/isdn/gigaset/ser-gigaset.c

   1 /* This is the serial hardware link layer (HLL) for the Gigaset 307x isdn
   2  * DECT base (aka Sinus 45 isdn) using the RS232 DECT data module M101,
   3  * written as a line discipline.
   4  *
   5  * =====================================================================
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of
   9  * the License, or (at your option) any later version.
  10  * =====================================================================
  11  */
  12
  13 #include "gigaset.h"
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/completion.h>
  18
  19 /* Version Information */
  20 #define DRIVER_AUTHOR "Tilman Schmidt"
  21 #define DRIVER_DESC "Serial Driver for Gigaset 307x using Siemens M101"
  22
  23 #define GIGASET_MINORS     1
  24 #define GIGASET_MINOR      0
  25 #define GIGASET_MODULENAME "ser_gigaset"
  26 #define GIGASET_DEVNAME    "ttyGS"
  27
  28 /* length limit according to Siemens 3070usb-protokoll.doc ch. 2.1 */
  29 #define IF_WRITEBUF 264
  30
  31 MODULE_AUTHOR(DRIVER_AUTHOR);
  32 MODULE_DESCRIPTION(DRIVER_DESC);
  33 MODULE_LICENSE("GPL");
  34 MODULE_ALIAS_LDISC(N_GIGASET_M101);
  35
  36 static int startmode = SM_ISDN;
  37 module_param(startmode, int, S_IRUGO);
  38 MODULE_PARM_DESC(startmode, "initial operation mode");
  39 static int cidmode = 1;
  40 module_param(cidmode, int, S_IRUGO);
  41 MODULE_PARM_DESC(cidmode, "stay in CID mode when idle");
  42
  43 static struct gigaset_driver *driver;
  44
  45 struct ser_cardstate {
  46         struct platform_device  dev;
  47         struct tty_struct       *tty;
  48         atomic_t                refcnt;
  49         struct completion       dead_cmp;
  50 };
  51
  52 static struct platform_driver device_driver = {
  53         .driver = {
  54                 .name = GIGASET_MODULENAME,
  55         },
  56 };
  57
  58 static void flush_send_queue(struct cardstate *);
  59
  60 /* transmit data from current open skb
  61  * result: number of bytes sent or error code < 0
  62  */
  63 static int write_modem(struct cardstate *cs)
  64 {
  65         struct tty_struct *tty = cs->hw.ser->tty;
  66         struct bc_state *bcs = &cs->bcs[0];     /* only one channel */
  67         struct sk_buff *skb = bcs->tx_skb;
  68         int sent = -EOPNOTSUPP;
  69
  70         if (!tty || !tty->driver || !skb)
  71                 return -EINVAL;
  72
  73         if (!skb->len) {
  74                 dev_kfree_skb_any(skb);
  75                 bcs->tx_skb = NULL;
  76                 return -EINVAL;
  77         }
  78
  79         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  80         if (tty->ops->write)
  81                 sent = tty->ops->write(tty, skb->data, skb->len);
  82         gig_dbg(DEBUG_OUTPUT, "write_modem: sent %d", sent);
  83         if (sent < 0) {
  84                 /* error */
  85                 flush_send_queue(cs);
  86                 return sent;
  87         }
  88         skb_pull(skb, sent);
  89         if (!skb->len) {
  90                 /* skb sent completely */
  91                 gigaset_skb_sent(bcs, skb);
  92
  93                 gig_dbg(DEBUG_INTR, "kfree skb (Adr: %lx)!",
  94                         (unsigned long) skb);
  95                 dev_kfree_skb_any(skb);
  96                 bcs->tx_skb = NULL;
  97         }
  98         return sent;
  99 }
 100
 101 /*
 102  * transmit first queued command buffer
 103  * result: number of bytes sent or error code < 0
 104  */
 105 static int send_cb(struct cardstate *cs)
 106 {
 107         struct tty_struct *tty = cs->hw.ser->tty;
 108         struct cmdbuf_t *cb, *tcb;
 109         unsigned long flags;
 110         int sent = 0;
 111
 112         if (!tty || !tty->driver)
 113                 return -EFAULT;
 114
 115         cb = cs->cmdbuf;
 116         if (!cb)
 117                 return 0;       /* nothing to do */
 118
 119         if (cb->len) {
 120                 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 121                 sent = tty->ops->write(tty, cb->buf + cb->offset, cb->len);
 122                 if (sent < 0) {
 123                         /* error */
 124                         gig_dbg(DEBUG_OUTPUT, "send_cb: write error %d", sent);
 125                         flush_send_queue(cs);
 126                         return sent;
 127                 }
 128                 cb->offset += sent;
 129                 cb->len -= sent;
 130                 gig_dbg(DEBUG_OUTPUT, "send_cb: sent %d, left %u, queued %u",
 131                         sent, cb->len, cs->cmdbytes);
 132         }
 133
 134         while (cb && !cb->len) {
 135                 spin_lock_irqsave(&cs->cmdlock, flags);
 136                 cs->cmdbytes -= cs->curlen;
 137                 tcb = cb;
 138                 cs->cmdbuf = cb = cb->next;
 139                 if (cb) {
 140                         cb->prev = NULL;
 141                         cs->curlen = cb->len;
 142                 } else {
 143                         cs->lastcmdbuf = NULL;
 144                         cs->curlen = 0;
 145                 }
 146                 spin_unlock_irqrestore(&cs->cmdlock, flags);
 147
 148                 if (tcb->wake_tasklet)
 149                         tasklet_schedule(tcb->wake_tasklet);
 150                 kfree(tcb);
 151         }
 152         return sent;
 153 }
 154
 155 /*
 156  * send queue tasklet
 157  * If there is already a skb opened, put data to the transfer buffer
 158  * by calling "write_modem".
 159  * Otherwise take a new skb out of the queue.
 160  */
 161 static void gigaset_modem_fill(unsigned long data)
 162 {
 163         struct cardstate *cs = (struct cardstate *) data;
 164         struct bc_state *bcs;
 165         struct sk_buff *nextskb;
 166         int sent = 0;
 167
 168         if (!cs) {
 169                 gig_dbg(DEBUG_OUTPUT, "%s: no cardstate", __func__);
 170                 return;
 171         }
 172         bcs = cs->bcs;
 173         if (!bcs) {
 174                 gig_dbg(DEBUG_OUTPUT, "%s: no cardstate", __func__);
 175                 return;
 176         }
 177         if (!bcs->tx_skb) {
 178                 /* no skb is being sent; send command if any */
 179                 sent = send_cb(cs);
 180                 gig_dbg(DEBUG_OUTPUT, "%s: send_cb -> %d", __func__, sent);
 181                 if (sent)
 182                         /* something sent or error */
 183                         return;
 184
 185                 /* no command to send; get skb */
 186                 nextskb = skb_dequeue(&bcs->squeue);
 187                 if (!nextskb)
 188                         /* no skb either, nothing to do */
 189                         return;
 190                 bcs->tx_skb = nextskb;
 191
 192                 gig_dbg(DEBUG_INTR, "Dequeued skb (Adr: %lx)",
 193                         (unsigned long) bcs->tx_skb);
 194         }
 195
 196         /* send skb */
 197         gig_dbg(DEBUG_OUTPUT, "%s: tx_skb", __func__);
 198         if (write_modem(cs) < 0)
 199                 gig_dbg(DEBUG_OUTPUT, "%s: write_modem failed", __func__);
 200 }
 201
 202 /*
 203  * throw away all data queued for sending
 204  */
 205 static void flush_send_queue(struct cardstate *cs)
 206 {
 207         struct sk_buff *skb;
 208         struct cmdbuf_t *cb;
 209         unsigned long flags;
 210
 211         /* command queue */
 212         spin_lock_irqsave(&cs->cmdlock, flags);
 213         while ((cb = cs->cmdbuf) != NULL) {
 214                 cs->cmdbuf = cb->next;
 215                 if (cb->wake_tasklet)
 216                         tasklet_schedule(cb->wake_tasklet);
 217                 kfree(cb);
 218         }
 219         cs->cmdbuf = cs->lastcmdbuf = NULL;
 220         cs->cmdbytes = cs->curlen = 0;
 221         spin_unlock_irqrestore(&cs->cmdlock, flags);
 222
 223         /* data queue */
 224         if (cs->bcs->tx_skb)
 225                 dev_kfree_skb_any(cs->bcs->tx_skb);
 226         while ((skb = skb_dequeue(&cs->bcs->squeue)) != NULL)
 227                 dev_kfree_skb_any(skb);
 228 }
 229
 230
 231 /* Gigaset Driver Interface */
 232 /* ======================== */
 233
 234 /*
 235  * queue an AT command string for transmission to the Gigaset device
 236  * parameters:
 237  *      cs              controller state structure
 238  *      buf             buffer containing the string to send
 239  *      len             number of characters to send
 240  *      wake_tasklet    tasklet to run when transmission is complete, or NULL
 241  * return value:
 242  *      number of bytes queued, or error code < 0
 243  */
 244 static int gigaset_write_cmd(struct cardstate *cs, struct cmdbuf_t *cb)
 245 {
 246         unsigned long flags;
 247
 248         gigaset_dbg_buffer(cs->mstate != MS_LOCKED ?
 249                                 DEBUG_TRANSCMD : DEBUG_LOCKCMD,
 250                            "CMD Transmit", cb->len, cb->buf);
 251
 252         spin_lock_irqsave(&cs->cmdlock, flags);
 253         cb->prev = cs->lastcmdbuf;
 254         if (cs->lastcmdbuf)
 255                 cs->lastcmdbuf->next = cb;
 256         else {
 257                 cs->cmdbuf = cb;
 258                 cs->curlen = cb->len;
 259         }
 260         cs->cmdbytes += cb->len;
 261         cs->lastcmdbuf = cb;
 262         spin_unlock_irqrestore(&cs->cmdlock, flags);
 263
 264         spin_lock_irqsave(&cs->lock, flags);
 265         if (cs->connected)
 266                 tasklet_schedule(&cs->write_tasklet);
 267         spin_unlock_irqrestore(&cs->lock, flags);
 268         return cb->len;
 269 }
 270
 271 /*
 272  * tty_driver.write_room interface routine
 273  * return number of characters the driver will accept to be written
 274  * parameter:
 275  *      controller state structure
 276  * return value:
 277  *      number of characters
 278  */
 279 static int gigaset_write_room(struct cardstate *cs)
 280 {
 281         unsigned bytes;
 282
 283         bytes = cs->cmdbytes;
 284         return bytes < IF_WRITEBUF ? IF_WRITEBUF - bytes : 0;
 285 }
 286
 287 /*
 288  * tty_driver.chars_in_buffer interface routine
 289  * return number of characters waiting to be sent
 290  * parameter:
 291  *      controller state structure
 292  * return value:
 293  *      number of characters
 294  */
 295 static int gigaset_chars_in_buffer(struct cardstate *cs)
 296 {
 297         return cs->cmdbytes;
 298 }
 299
 300 /*
 301  * implementation of ioctl(GIGASET_BRKCHARS)
 302  * parameter:
 303  *      controller state structure
 304  * return value:
 305  *      -EINVAL (unimplemented function)
 306  */
 307 static int gigaset_brkchars(struct cardstate *cs, const unsigned char buf[6])
 308 {
 309         /* not implemented */
 310         return -EINVAL;
 311 }
 312
 313 /*
 314  * Open B channel
 315  * Called by "do_action" in ev-layer.c
 316  */
 317 static int gigaset_init_bchannel(struct bc_state *bcs)
 318 {
 319         /* nothing to do for M10x */
 320         gigaset_bchannel_up(bcs);
 321         return 0;
 322 }
 323
 324 /*
 325  * Close B channel
 326  * Called by "do_action" in ev-layer.c
 327  */
 328 static int gigaset_close_bchannel(struct bc_state *bcs)
 329 {
 330         /* nothing to do for M10x */
 331         gigaset_bchannel_down(bcs);
 332         return 0;
 333 }
 334
 335 /*
 336  * Set up B channel structure
 337  * This is called by "gigaset_initcs" in common.c
 338  */
 339 static int gigaset_initbcshw(struct bc_state *bcs)
 340 {
 341         /* unused */
 342         bcs->hw.ser = NULL;
 343         return 1;
 344 }
 345
 346 /*
 347  * Free B channel structure
 348  * Called by "gigaset_freebcs" in common.c
 349  */
 350 static int gigaset_freebcshw(struct bc_state *bcs)
 351 {
 352         /* unused */
 353         return 1;
 354 }
 355
 356 /*
 357  * Reinitialize B channel structure
 358  * This is called by "bcs_reinit" in common.c
 359  */
 360 static void gigaset_reinitbcshw(struct bc_state *bcs)
 361 {
 362         /* nothing to do for M10x */
 363 }
 364
 365 /*
 366  * Free hardware specific device data
 367  * This will be called by "gigaset_freecs" in common.c
 368  */
 369 static void gigaset_freecshw(struct cardstate *cs)
 370 {
 371         tasklet_kill(&cs->write_tasklet);
 372         if (!cs->hw.ser)
 373                 return;
 374         platform_device_unregister(&cs->hw.ser->dev);
 375 }
 376
 377 static void gigaset_device_release(struct device *dev)
 378 {
 379         struct platform_device *pdev = to_platform_device(dev);
 380         struct cardstate *cs = dev_get_drvdata(dev);
 381
 382         /* adapted from platform_device_release() in drivers/base/platform.c */
 383         kfree(dev->platform_data);
 384         kfree(pdev->resource);
 385
 386         if (!cs)
 387                 return;
 388         dev_set_drvdata(dev, NULL);
 389         kfree(cs->hw.ser);
 390         cs->hw.ser = NULL;
 391 }
 392
 393 /*
 394  * Set up hardware specific device data
 395  * This is called by "gigaset_initcs" in common.c
 396  */
 397 static int gigaset_initcshw(struct cardstate *cs)
 398 {
 399         int rc;
 400         struct ser_cardstate *scs;
 401
 402         scs = kzalloc(sizeof(struct ser_cardstate), GFP_KERNEL);
 403         if (!scs) {
 404                 pr_err("out of memory\n");
 405                 return 0;
 406         }
 407         cs->hw.ser = scs;
 408
 409         cs->hw.ser->dev.name = GIGASET_MODULENAME;
 410         cs->hw.ser->dev.id = cs->minor_index;
 411         cs->hw.ser->dev.dev.release = gigaset_device_release;
 412         rc = platform_device_register(&cs->hw.ser->dev);
 413         if (rc != 0) {
 414                 pr_err("error %d registering platform device\n", rc);
 415                 kfree(cs->hw.ser);
 416                 cs->hw.ser = NULL;
 417                 return 0;
 418         }
 419         dev_set_drvdata(&cs->hw.ser->dev.dev, cs);
 420
 421         tasklet_init(&cs->write_tasklet,
 422                      gigaset_modem_fill, (unsigned long) cs);
 423         return 1;
 424 }
 425
 426 /*
 427  * set modem control lines
 428  * Parameters:
 429  *      card state structure
 430  *      modem control line state ([TIOCM_DTR]|[TIOCM_RTS])
 431  * Called by "gigaset_start" and "gigaset_enterconfigmode" in common.c
 432  * and by "if_lock" and "if_termios" in interface.c
 433  */
 434 static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state,
 435                                   unsigned new_state)
 436 {
 437         struct tty_struct *tty = cs->hw.ser->tty;
 438         unsigned int set, clear;
 439
 440         if (!tty || !tty->driver || !tty->ops->tiocmset)
 441                 return -EINVAL;
 442         set = new_state & ~old_state;
 443         clear = old_state & ~new_state;
 444         if (!set && !clear)
 445                 return 0;
 446         gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
 447         return tty->ops->tiocmset(tty, set, clear);
 448 }
 449
 450 static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
 451 {
 452         return -EINVAL;
 453 }
 454
 455 static int gigaset_set_line_ctrl(struct cardstate *cs, unsigned cflag)
 456 {
 457         return -EINVAL;
 458 }
 459
 460 static const struct gigaset_ops ops = {
 461         gigaset_write_cmd,
 462         gigaset_write_room,
 463         gigaset_chars_in_buffer,
 464         gigaset_brkchars,
 465         gigaset_init_bchannel,
 466         gigaset_close_bchannel,
 467         gigaset_initbcshw,
 468         gigaset_freebcshw,
 469         gigaset_reinitbcshw,
 470         gigaset_initcshw,
 471         gigaset_freecshw,
 472         gigaset_set_modem_ctrl,
 473         gigaset_baud_rate,
 474         gigaset_set_line_ctrl,
 475         gigaset_m10x_send_skb,  /* asyncdata.c */
 476         gigaset_m10x_input,     /* asyncdata.c */
 477 };
 478
 479
 480 /* Line Discipline Interface */
 481 /* ========================= */
 482
 483 /* helper functions for cardstate refcounting */
 484 static struct cardstate *cs_get(struct tty_struct *tty)
 485 {
 486         struct cardstate *cs = tty->disc_data;
 487
 488         if (!cs || !cs->hw.ser) {
 489                 gig_dbg(DEBUG_ANY, "%s: no cardstate", __func__);
 490                 return NULL;
 491         }
 492         atomic_inc(&cs->hw.ser->refcnt);
 493         return cs;
 494 }
 495
 496 static void cs_put(struct cardstate *cs)
 497 {
 498         if (atomic_dec_and_test(&cs->hw.ser->refcnt))
 499                 complete(&cs->hw.ser->dead_cmp);
 500 }
 501
 502 /*
 503  * Called by the tty driver when the line discipline is pushed onto the tty.
 504  * Called in process context.
 505  */
 506 static int
 507 gigaset_tty_open(struct tty_struct *tty)
 508 {
 509         struct cardstate *cs;
 510
 511         gig_dbg(DEBUG_INIT, "Starting HLL for Gigaset M101");
 512
 513         pr_info(DRIVER_DESC "\n");
 514
 515         if (!driver) {
 516                 pr_err("%s: no driver structure\n", __func__);
 517                 return -ENODEV;
 518         }
 519
 520         /* allocate memory for our device state and initialize it */
 521         cs = gigaset_initcs(driver, 1, 1, 0, cidmode, GIGASET_MODULENAME);
 522         if (!cs)
 523                 goto error;
 524
 525         cs->dev = &cs->hw.ser->dev.dev;
 526         cs->hw.ser->tty = tty;
 527         atomic_set(&cs->hw.ser->refcnt, 1);
 528         init_completion(&cs->hw.ser->dead_cmp);
 529
 530         tty->disc_data = cs;
 531
 532         /* OK.. Initialization of the datastructures and the HW is done.. Now
 533          * startup system and notify the LL that we are ready to run
 534          */
 535         if (startmode == SM_LOCKED)
 536                 cs->mstate = MS_LOCKED;
 537         if (!gigaset_start(cs)) {
 538                 tasklet_kill(&cs->write_tasklet);
 539                 goto error;
 540         }
 541
 542         gig_dbg(DEBUG_INIT, "Startup of HLL done");
 543         return 0;
 544
 545 error:
 546         gig_dbg(DEBUG_INIT, "Startup of HLL failed");
 547         tty->disc_data = NULL;
 548         gigaset_freecs(cs);
 549         return -ENODEV;
 550 }
 551
 552 /*
 553  * Called by the tty driver when the line discipline is removed.
 554  * Called from process context.
 555  */
 556 static void
 557 gigaset_tty_close(struct tty_struct *tty)
 558 {
 559         struct cardstate *cs = tty->disc_data;
 560
 561         gig_dbg(DEBUG_INIT, "Stopping HLL for Gigaset M101");
 562
 563         if (!cs) {
 564                 gig_dbg(DEBUG_INIT, "%s: no cardstate", __func__);
 565                 return;
 566         }
 567
 568         /* prevent other callers from entering ldisc methods */
 569         tty->disc_data = NULL;
 570
 571         if (!cs->hw.ser)
 572                 pr_err("%s: no hw cardstate\n", __func__);
 573         else {
 574                 /* wait for running methods to finish */
 575                 if (!atomic_dec_and_test(&cs->hw.ser->refcnt))
 576                         wait_for_completion(&cs->hw.ser->dead_cmp);
 577         }
 578
 579         /* stop operations */
 580         gigaset_stop(cs);
 581         tasklet_kill(&cs->write_tasklet);
 582         flush_send_queue(cs);
 583         cs->dev = NULL;
 584         gigaset_freecs(cs);
 585
 586         gig_dbg(DEBUG_INIT, "Shutdown of HLL done");
 587 }
 588
 589 /*
 590  * Called by the tty driver when the tty line is hung up.
 591  * Wait for I/O to driver to complete and unregister ISDN device.
 592  * This is already done by the close routine, so just call that.
 593  * Called from process context.
 594  */
 595 static int gigaset_tty_hangup(struct tty_struct *tty)
 596 {
 597         gigaset_tty_close(tty);
 598         return 0;
 599 }
 600
 601 /*
 602  * Read on the tty.
 603  * Unused, received data goes only to the Gigaset driver.
 604  */
 605 static ssize_t
 606 gigaset_tty_read(struct tty_struct *tty, struct file *file,
 607                  unsigned char __user *buf, size_t count)
 608 {
 609         return -EAGAIN;
 610 }
 611
 612 /*
 613  * Write on the tty.
 614  * Unused, transmit data comes only from the Gigaset driver.
 615  */
 616 static ssize_t
 617 gigaset_tty_write(struct tty_struct *tty, struct file *file,
 618                   const unsigned char *buf, size_t count)
 619 {
 620         return -EAGAIN;
 621 }
 622
 623 /*
 624  * Ioctl on the tty.
 625  * Called in process context only.
 626  * May be re-entered by multiple ioctl calling threads.
 627  */
 628 static int
 629 gigaset_tty_ioctl(struct tty_struct *tty, struct file *file,
 630                   unsigned int cmd, unsigned long arg)
 631 {
 632         struct cardstate *cs = cs_get(tty);
 633         int rc, val;
 634         int __user *p = (int __user *)arg;
 635
 636         if (!cs)
 637                 return -ENXIO;
 638
 639         switch (cmd) {
 640
 641         case FIONREAD:
 642                 /* unused, always return zero */
 643                 val = 0;
 644                 rc = put_user(val, p);
 645                 break;
 646
 647         case TCFLSH:
 648                 /* flush our buffers and the serial port's buffer */
 649                 switch (arg) {
 650                 case TCIFLUSH:
 651                         /* no own input buffer to flush */
 652                         break;
 653                 case TCIOFLUSH:
 654                 case TCOFLUSH:
 655                         flush_send_queue(cs);
 656                         break;
 657                 }
 658                 /* Pass through */
 659
 660         default:
 661                 /* pass through to underlying serial device */
 662                 rc = n_tty_ioctl_helper(tty, file, cmd, arg);
 663                 break;
 664         }
 665         cs_put(cs);
 666         return rc;
 667 }
 668
 669 /*
 670  * Called by the tty driver when a block of data has been received.
 671  * Will not be re-entered while running but other ldisc functions
 672  * may be called in parallel.
 673  * Can be called from hard interrupt level as well as soft interrupt
 674  * level or mainline.
 675  * Parameters:
 676  *      tty     tty structure
 677  *      buf     buffer containing received characters
 678  *      cflags  buffer containing error flags for received characters (ignored)
 679  *      count   number of received characters
 680  */
 681 static void
 682 gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
 683                     char *cflags, int count)
 684 {
 685         struct cardstate *cs = cs_get(tty);
 686         unsigned tail, head, n;
 687         struct inbuf_t *inbuf;
 688
 689         if (!cs)
 690                 return;
 691         inbuf = cs->inbuf;
 692         if (!inbuf) {
 693                 dev_err(cs->dev, "%s: no inbuf\n", __func__);
 694                 cs_put(cs);
 695                 return;
 696         }
 697
 698         tail = inbuf->tail;
 699         head = inbuf->head;
 700         gig_dbg(DEBUG_INTR, "buffer state: %u -> %u, receive %u bytes",
 701                 head, tail, count);
 702
 703         if (head <= tail) {
 704                 /* possible buffer wraparound */
 705                 n = min_t(unsigned, count, RBUFSIZE - tail);
 706                 memcpy(inbuf->data + tail, buf, n);
 707                 tail = (tail + n) % RBUFSIZE;
 708                 buf += n;
 709                 count -= n;
 710         }
 711
 712         if (count > 0) {
 713                 /* tail < head and some data left */
 714                 n = head - tail - 1;
 715                 if (count > n) {
 716                         dev_err(cs->dev,
 717                                 "inbuf overflow, discarding %d bytes\n",
 718                                 count - n);
 719                         count = n;
 720                 }
 721                 memcpy(inbuf->data + tail, buf, count);
 722                 tail += count;
 723         }
 724
 725         gig_dbg(DEBUG_INTR, "setting tail to %u", tail);
 726         inbuf->tail = tail;
 727
 728         /* Everything was received .. Push data into handler */
 729         gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
 730         gigaset_schedule_event(cs);
 731         cs_put(cs);
 732 }
 733
 734 /*
 735  * Called by the tty driver when there's room for more data to send.
 736  */
 737 static void
 738 gigaset_tty_wakeup(struct tty_struct *tty)
 739 {
 740         struct cardstate *cs = cs_get(tty);
 741
 742         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 743         if (!cs)
 744                 return;
 745         tasklet_schedule(&cs->write_tasklet);
 746         cs_put(cs);
 747 }
 748
 749 static struct tty_ldisc_ops gigaset_ldisc = {
 750         .owner          = THIS_MODULE,
 751         .magic          = TTY_LDISC_MAGIC,
 752         .name           = "ser_gigaset",
 753         .open           = gigaset_tty_open,
 754         .close          = gigaset_tty_close,
 755         .hangup         = gigaset_tty_hangup,
 756         .read           = gigaset_tty_read,
 757         .write          = gigaset_tty_write,
 758         .ioctl          = gigaset_tty_ioctl,
 759         .receive_buf    = gigaset_tty_receive,
 760         .write_wakeup   = gigaset_tty_wakeup,
 761 };
 762
 763
 764 /* Initialization / Shutdown */
 765 /* ========================= */
 766
 767 static int __init ser_gigaset_init(void)
 768 {
 769         int rc;
 770
 771         gig_dbg(DEBUG_INIT, "%s", __func__);
 772         rc = platform_driver_register(&device_driver);
 773         if (rc != 0) {
 774                 pr_err("error %d registering platform driver\n", rc);
 775                 return rc;
 776         }
 777
 778         /* allocate memory for our driver state and initialize it */
 779         driver = gigaset_initdriver(GIGASET_MINOR, GIGASET_MINORS,
 780                                           GIGASET_MODULENAME, GIGASET_DEVNAME,
 781                                           &ops, THIS_MODULE);
 782         if (!driver)
 783                 goto error;
 784
 785         rc = tty_register_ldisc(N_GIGASET_M101, &gigaset_ldisc);
 786         if (rc != 0) {
 787                 pr_err("error %d registering line discipline\n", rc);
 788                 goto error;
 789         }
 790
 791         return 0;
 792
 793 error:
 794         if (driver) {
 795                 gigaset_freedriver(driver);
 796                 driver = NULL;
 797         }
 798         platform_driver_unregister(&device_driver);
 799         return rc;
 800 }
 801
 802 static void __exit ser_gigaset_exit(void)
 803 {
 804         int rc;
 805
 806         gig_dbg(DEBUG_INIT, "%s", __func__);
 807
 808         if (driver) {
 809                 gigaset_freedriver(driver);
 810                 driver = NULL;
 811         }
 812
 813         rc = tty_unregister_ldisc(N_GIGASET_M101);
 814         if (rc != 0)
 815                 pr_err("error %d unregistering line discipline\n", rc);
 816
 817         platform_driver_unregister(&device_driver);
 818 }
 819
 820 module_init(ser_gigaset_init);
 821 module_exit(ser_gigaset_exit);