git.oblomov.eu Git - linux-2.6/blob - 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
  15 #include <linux/module.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/tty.h>
  19 #include <linux/completion.h>
  20
  21 /* Version Information */
  22 #define DRIVER_AUTHOR "Tilman Schmidt"
  23 #define DRIVER_DESC "Serial Driver for Gigaset 307x using Siemens M101"
  24
  25 #define GIGASET_MINORS     1
  26 #define GIGASET_MINOR      0
  27 #define GIGASET_MODULENAME "ser_gigaset"
  28 #define GIGASET_DEVNAME    "ttyGS"
  29
  30 /* length limit according to Siemens 3070usb-protokoll.doc ch. 2.1 */
  31 #define IF_WRITEBUF 264
  32
  33 MODULE_AUTHOR(DRIVER_AUTHOR);
  34 MODULE_DESCRIPTION(DRIVER_DESC);
  35 MODULE_LICENSE("GPL");
  36 MODULE_ALIAS_LDISC(N_GIGASET_M101);
  37
  38 static int startmode = SM_ISDN;
  39 module_param(startmode, int, S_IRUGO);
  40 MODULE_PARM_DESC(startmode, "initial operation mode");
  41 static int cidmode = 1;
  42 module_param(cidmode, int, S_IRUGO);
  43 MODULE_PARM_DESC(cidmode, "stay in CID mode when idle");
  44
  45 static struct gigaset_driver *driver;
  46
  47 struct ser_cardstate {
  48         struct platform_device  dev;
  49         struct tty_struct       *tty;
  50         atomic_t                refcnt;
  51         struct completion       dead_cmp;
  52 };
  53
  54 static struct platform_driver device_driver = {
  55         .driver = {
  56                 .name = GIGASET_MODULENAME,
  57         },
  58 };
  59
  60 static void flush_send_queue(struct cardstate *);
  61
  62 /* transmit data from current open skb
  63  * result: number of bytes sent or error code < 0
  64  */
  65 static int write_modem(struct cardstate *cs)
  66 {
  67         struct tty_struct *tty = cs->hw.ser->tty;
  68         struct bc_state *bcs = &cs->bcs[0];     /* only one channel */
  69         struct sk_buff *skb = bcs->tx_skb;
  70         int sent = -EOPNOTSUPP;
  71
  72         if (!tty || !tty->driver || !skb)
  73                 return -EINVAL;
  74
  75         if (!skb->len) {
  76                 dev_kfree_skb_any(skb);
  77                 bcs->tx_skb = NULL;
  78                 return -EINVAL;
  79         }
  80
  81         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  82         if (tty->ops->write)
  83                 sent = tty->ops->write(tty, skb->data, skb->len);
  84         gig_dbg(DEBUG_OUTPUT, "write_modem: sent %d", sent);
  85         if (sent < 0) {
  86                 /* error */
  87                 flush_send_queue(cs);
  88                 return sent;
  89         }
  90         skb_pull(skb, sent);
  91         if (!skb->len) {
  92                 /* skb sent completely */
  93                 gigaset_skb_sent(bcs, skb);
  94
  95                 gig_dbg(DEBUG_INTR, "kfree skb (Adr: %lx)!",
  96                         (unsigned long) skb);
  97                 dev_kfree_skb_any(skb);
  98                 bcs->tx_skb = NULL;
  99         }
 100         return sent;
 101 }
 102
 103 /*
 104  * transmit first queued command buffer
 105  * result: number of bytes sent or error code < 0
 106  */
 107 static int send_cb(struct cardstate *cs)
 108 {
 109         struct tty_struct *tty = cs->hw.ser->tty;
 110         struct cmdbuf_t *cb, *tcb;
 111         unsigned long flags;
 112         int sent = 0;
 113
 114         if (!tty || !tty->driver)
 115                 return -EFAULT;
 116
 117         cb = cs->cmdbuf;
 118         if (!cb)
 119                 return 0;       /* nothing to do */
 120
 121         if (cb->len) {
 122                 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 123                 sent = tty->ops->write(tty, cb->buf + cb->offset, cb->len);
 124                 if (sent < 0) {
 125                         /* error */
 126                         gig_dbg(DEBUG_OUTPUT, "send_cb: write error %d", sent);
 127                         flush_send_queue(cs);
 128                         return sent;
 129                 }
 130                 cb->offset += sent;
 131                 cb->len -= sent;
 132                 gig_dbg(DEBUG_OUTPUT, "send_cb: sent %d, left %u, queued %u",
 133                         sent, cb->len, cs->cmdbytes);
 134         }
 135
 136         while (cb && !cb->len) {
 137                 spin_lock_irqsave(&cs->cmdlock, flags);
 138                 cs->cmdbytes -= cs->curlen;
 139                 tcb = cb;
 140                 cs->cmdbuf = cb = cb->next;
 141                 if (cb) {
 142                         cb->prev = NULL;
 143                         cs->curlen = cb->len;
 144                 } else {
 145                         cs->lastcmdbuf = NULL;
 146                         cs->curlen = 0;
 147                 }
 148                 spin_unlock_irqrestore(&cs->cmdlock, flags);
 149
 150                 if (tcb->wake_tasklet)
 151                         tasklet_schedule(tcb->wake_tasklet);
 152                 kfree(tcb);
 153         }
 154         return sent;
 155 }
 156
 157 /*
 158  * send queue tasklet
 159  * If there is already a skb opened, put data to the transfer buffer
 160  * by calling "write_modem".
 161  * Otherwise take a new skb out of the queue.
 162  */
 163 static void gigaset_modem_fill(unsigned long data)
 164 {
 165         struct cardstate *cs = (struct cardstate *) data;
 166         struct bc_state *bcs;
 167         int sent = 0;
 168
 169         if (!cs || !(bcs = cs->bcs)) {
 170                 gig_dbg(DEBUG_OUTPUT, "%s: no cardstate", __func__);
 171                 return;
 172         }
 173         if (!bcs->tx_skb) {
 174                 /* no skb is being sent; send command if any */
 175                 sent = send_cb(cs);
 176                 gig_dbg(DEBUG_OUTPUT, "%s: send_cb -> %d", __func__, sent);
 177                 if (sent)
 178                         /* something sent or error */
 179                         return;
 180
 181                 /* no command to send; get skb */
 182                 if (!(bcs->tx_skb = skb_dequeue(&bcs->squeue)))
 183                         /* no skb either, nothing to do */
 184                         return;
 185
 186                 gig_dbg(DEBUG_INTR, "Dequeued skb (Adr: %lx)",
 187                         (unsigned long) bcs->tx_skb);
 188         }
 189
 190         /* send skb */
 191         gig_dbg(DEBUG_OUTPUT, "%s: tx_skb", __func__);
 192         if (write_modem(cs) < 0)
 193                 gig_dbg(DEBUG_OUTPUT, "%s: write_modem failed", __func__);
 194 }
 195
 196 /*
 197  * throw away all data queued for sending
 198  */
 199 static void flush_send_queue(struct cardstate *cs)
 200 {
 201         struct sk_buff *skb;
 202         struct cmdbuf_t *cb;
 203         unsigned long flags;
 204
 205         /* command queue */
 206         spin_lock_irqsave(&cs->cmdlock, flags);
 207         while ((cb = cs->cmdbuf) != NULL) {
 208                 cs->cmdbuf = cb->next;
 209                 if (cb->wake_tasklet)
 210                         tasklet_schedule(cb->wake_tasklet);
 211                 kfree(cb);
 212         }
 213         cs->cmdbuf = cs->lastcmdbuf = NULL;
 214         cs->cmdbytes = cs->curlen = 0;
 215         spin_unlock_irqrestore(&cs->cmdlock, flags);
 216
 217         /* data queue */
 218         if (cs->bcs->tx_skb)
 219                 dev_kfree_skb_any(cs->bcs->tx_skb);
 220         while ((skb = skb_dequeue(&cs->bcs->squeue)) != NULL)
 221                 dev_kfree_skb_any(skb);
 222 }
 223
 224
 225 /* Gigaset Driver Interface */
 226 /* ======================== */
 227
 228 /*
 229  * queue an AT command string for transmission to the Gigaset device
 230  * parameters:
 231  *      cs              controller state structure
 232  *      buf             buffer containing the string to send
 233  *      len             number of characters to send
 234  *      wake_tasklet    tasklet to run when transmission is complete, or NULL
 235  * return value:
 236  *      number of bytes queued, or error code < 0
 237  */
 238 static int gigaset_write_cmd(struct cardstate *cs, const unsigned char *buf,
 239                              int len, struct tasklet_struct *wake_tasklet)
 240 {
 241         struct cmdbuf_t *cb;
 242         unsigned long flags;
 243
 244         gigaset_dbg_buffer(cs->mstate != MS_LOCKED ?
 245                              DEBUG_TRANSCMD : DEBUG_LOCKCMD,
 246                            "CMD Transmit", len, buf);
 247
 248         if (len <= 0)
 249                 return 0;
 250
 251         if (!(cb = kmalloc(sizeof(struct cmdbuf_t) + len, GFP_ATOMIC))) {
 252                 dev_err(cs->dev, "%s: out of memory!\n", __func__);
 253                 return -ENOMEM;
 254         }
 255
 256         memcpy(cb->buf, buf, len);
 257         cb->len = len;
 258         cb->offset = 0;
 259         cb->next = NULL;
 260         cb->wake_tasklet = wake_tasklet;
 261
 262         spin_lock_irqsave(&cs->cmdlock, flags);
 263         cb->prev = cs->lastcmdbuf;
 264         if (cs->lastcmdbuf)
 265                 cs->lastcmdbuf->next = cb;
 266         else {
 267                 cs->cmdbuf = cb;
 268                 cs->curlen = len;
 269         }
 270         cs->cmdbytes += len;
 271         cs->lastcmdbuf = cb;
 272         spin_unlock_irqrestore(&cs->cmdlock, flags);
 273
 274         spin_lock_irqsave(&cs->lock, flags);
 275         if (cs->connected)
 276                 tasklet_schedule(&cs->write_tasklet);
 277         spin_unlock_irqrestore(&cs->lock, flags);
 278         return len;
 279 }
 280
 281 /*
 282  * tty_driver.write_room interface routine
 283  * return number of characters the driver will accept to be written
 284  * parameter:
 285  *      controller state structure
 286  * return value:
 287  *      number of characters
 288  */
 289 static int gigaset_write_room(struct cardstate *cs)
 290 {
 291         unsigned bytes;
 292
 293         bytes = cs->cmdbytes;
 294         return bytes < IF_WRITEBUF ? IF_WRITEBUF - bytes : 0;
 295 }
 296
 297 /*
 298  * tty_driver.chars_in_buffer interface routine
 299  * return number of characters waiting to be sent
 300  * parameter:
 301  *      controller state structure
 302  * return value:
 303  *      number of characters
 304  */
 305 static int gigaset_chars_in_buffer(struct cardstate *cs)
 306 {
 307         return cs->cmdbytes;
 308 }
 309
 310 /*
 311  * implementation of ioctl(GIGASET_BRKCHARS)
 312  * parameter:
 313  *      controller state structure
 314  * return value:
 315  *      -EINVAL (unimplemented function)
 316  */
 317 static int gigaset_brkchars(struct cardstate *cs, const unsigned char buf[6])
 318 {
 319         /* not implemented */
 320         return -EINVAL;
 321 }
 322
 323 /*
 324  * Open B channel
 325  * Called by "do_action" in ev-layer.c
 326  */
 327 static int gigaset_init_bchannel(struct bc_state *bcs)
 328 {
 329         /* nothing to do for M10x */
 330         gigaset_bchannel_up(bcs);
 331         return 0;
 332 }
 333
 334 /*
 335  * Close B channel
 336  * Called by "do_action" in ev-layer.c
 337  */
 338 static int gigaset_close_bchannel(struct bc_state *bcs)
 339 {
 340         /* nothing to do for M10x */
 341         gigaset_bchannel_down(bcs);
 342         return 0;
 343 }
 344
 345 /*
 346  * Set up B channel structure
 347  * This is called by "gigaset_initcs" in common.c
 348  */
 349 static int gigaset_initbcshw(struct bc_state *bcs)
 350 {
 351         /* unused */
 352         bcs->hw.ser = NULL;
 353         return 1;
 354 }
 355
 356 /*
 357  * Free B channel structure
 358  * Called by "gigaset_freebcs" in common.c
 359  */
 360 static int gigaset_freebcshw(struct bc_state *bcs)
 361 {
 362         /* unused */
 363         return 1;
 364 }
 365
 366 /*
 367  * Reinitialize B channel structure
 368  * This is called by "bcs_reinit" in common.c
 369  */
 370 static void gigaset_reinitbcshw(struct bc_state *bcs)
 371 {
 372         /* nothing to do for M10x */
 373 }
 374
 375 /*
 376  * Free hardware specific device data
 377  * This will be called by "gigaset_freecs" in common.c
 378  */
 379 static void gigaset_freecshw(struct cardstate *cs)
 380 {
 381         tasklet_kill(&cs->write_tasklet);
 382         if (!cs->hw.ser)
 383                 return;
 384         dev_set_drvdata(&cs->hw.ser->dev.dev, NULL);
 385         platform_device_unregister(&cs->hw.ser->dev);
 386         kfree(cs->hw.ser);
 387         cs->hw.ser = NULL;
 388 }
 389
 390 static void gigaset_device_release(struct device *dev)
 391 {
 392         struct platform_device *pdev = to_platform_device(dev);
 393
 394         /* adapted from platform_device_release() in drivers/base/platform.c */
 395         //FIXME is this actually necessary?
 396         kfree(dev->platform_data);
 397         kfree(pdev->resource);
 398 }
 399
 400 /*
 401  * Set up hardware specific device data
 402  * This is called by "gigaset_initcs" in common.c
 403  */
 404 static int gigaset_initcshw(struct cardstate *cs)
 405 {
 406         int rc;
 407
 408         if (!(cs->hw.ser = kzalloc(sizeof(struct ser_cardstate), GFP_KERNEL))) {
 409                 pr_err("out of memory\n");
 410                 return 0;
 411         }
 412
 413         cs->hw.ser->dev.name = GIGASET_MODULENAME;
 414         cs->hw.ser->dev.id = cs->minor_index;
 415         cs->hw.ser->dev.dev.release = gigaset_device_release;
 416         if ((rc = platform_device_register(&cs->hw.ser->dev)) != 0) {
 417                 pr_err("error %d registering platform device\n", rc);
 418                 kfree(cs->hw.ser);
 419                 cs->hw.ser = NULL;
 420                 return 0;
 421         }
 422         dev_set_drvdata(&cs->hw.ser->dev.dev, cs);
 423
 424         tasklet_init(&cs->write_tasklet,
 425                      &gigaset_modem_fill, (unsigned long) cs);
 426         return 1;
 427 }
 428
 429 /*
 430  * set modem control lines
 431  * Parameters:
 432  *      card state structure
 433  *      modem control line state ([TIOCM_DTR]|[TIOCM_RTS])
 434  * Called by "gigaset_start" and "gigaset_enterconfigmode" in common.c
 435  * and by "if_lock" and "if_termios" in interface.c
 436  */
 437 static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state, unsigned new_state)
 438 {
 439         struct tty_struct *tty = cs->hw.ser->tty;
 440         unsigned int set, clear;
 441
 442         if (!tty || !tty->driver || !tty->ops->tiocmset)
 443                 return -EINVAL;
 444         set = new_state & ~old_state;
 445         clear = old_state & ~new_state;
 446         if (!set && !clear)
 447                 return 0;
 448         gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
 449         return tty->ops->tiocmset(tty, NULL, set, clear);
 450 }
 451
 452 static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
 453 {
 454         return -EINVAL;
 455 }
 456
 457 static int gigaset_set_line_ctrl(struct cardstate *cs, unsigned cflag)
 458 {
 459         return -EINVAL;
 460 }
 461
 462 static const struct gigaset_ops ops = {
 463         gigaset_write_cmd,
 464         gigaset_write_room,
 465         gigaset_chars_in_buffer,
 466         gigaset_brkchars,
 467         gigaset_init_bchannel,
 468         gigaset_close_bchannel,
 469         gigaset_initbcshw,
 470         gigaset_freebcshw,
 471         gigaset_reinitbcshw,
 472         gigaset_initcshw,
 473         gigaset_freecshw,
 474         gigaset_set_modem_ctrl,
 475         gigaset_baud_rate,
 476         gigaset_set_line_ctrl,
 477         gigaset_m10x_send_skb,  /* asyncdata.c */
 478         gigaset_m10x_input,     /* asyncdata.c */
 479 };
 480
 481
 482 /* Line Discipline Interface */
 483 /* ========================= */
 484
 485 /* helper functions for cardstate refcounting */
 486 static struct cardstate *cs_get(struct tty_struct *tty)
 487 {
 488         struct cardstate *cs = tty->disc_data;
 489
 490         if (!cs || !cs->hw.ser) {
 491                 gig_dbg(DEBUG_ANY, "%s: no cardstate", __func__);
 492                 return NULL;
 493         }
 494         atomic_inc(&cs->hw.ser->refcnt);
 495         return cs;
 496 }
 497
 498 static void cs_put(struct cardstate *cs)
 499 {
 500         if (atomic_dec_and_test(&cs->hw.ser->refcnt))
 501                 complete(&cs->hw.ser->dead_cmp);
 502 }
 503
 504 /*
 505  * Called by the tty driver when the line discipline is pushed onto the tty.
 506  * Called in process context.
 507  */
 508 static int
 509 gigaset_tty_open(struct tty_struct *tty)
 510 {
 511         struct cardstate *cs;
 512
 513         gig_dbg(DEBUG_INIT, "Starting HLL for Gigaset M101");
 514
 515         pr_info(DRIVER_DESC "\n");
 516
 517         if (!driver) {
 518                 pr_err("%s: no driver structure\n", __func__);
 519                 return -ENODEV;
 520         }
 521
 522         /* allocate memory for our device state and intialize it */
 523         if (!(cs = gigaset_initcs(driver, 1, 1, 0, cidmode,
 524                                   GIGASET_MODULENAME)))
 525                 goto error;
 526
 527         cs->dev = &cs->hw.ser->dev.dev;
 528         cs->hw.ser->tty = tty;
 529         atomic_set(&cs->hw.ser->refcnt, 1);
 530         init_completion(&cs->hw.ser->dead_cmp);
 531
 532         tty->disc_data = cs;
 533
 534         /* OK.. Initialization of the datastructures and the HW is done.. Now
 535          * startup system and notify the LL that we are ready to run
 536          */
 537         if (startmode == SM_LOCKED)
 538                 cs->mstate = MS_LOCKED;
 539         if (!gigaset_start(cs)) {
 540                 tasklet_kill(&cs->write_tasklet);
 541                 goto error;
 542         }
 543
 544         gig_dbg(DEBUG_INIT, "Startup of HLL done");
 545         return 0;
 546
 547 error:
 548         gig_dbg(DEBUG_INIT, "Startup of HLL failed");
 549         tty->disc_data = NULL;
 550         gigaset_freecs(cs);
 551         return -ENODEV;
 552 }
 553
 554 /*
 555  * Called by the tty driver when the line discipline is removed.
 556  * Called from process context.
 557  */
 558 static void
 559 gigaset_tty_close(struct tty_struct *tty)
 560 {
 561         struct cardstate *cs = tty->disc_data;
 562
 563         gig_dbg(DEBUG_INIT, "Stopping HLL for Gigaset M101");
 564
 565         if (!cs) {
 566                 gig_dbg(DEBUG_INIT, "%s: no cardstate", __func__);
 567                 return;
 568         }
 569
 570         /* prevent other callers from entering ldisc methods */
 571         tty->disc_data = NULL;
 572
 573         if (!cs->hw.ser)
 574                 pr_err("%s: no hw cardstate\n", __func__);
 575         else {
 576                 /* wait for running methods to finish */
 577                 if (!atomic_dec_and_test(&cs->hw.ser->refcnt))
 578                         wait_for_completion(&cs->hw.ser->dead_cmp);
 579         }
 580
 581         /* stop operations */
 582         gigaset_stop(cs);
 583         tasklet_kill(&cs->write_tasklet);
 584         flush_send_queue(cs);
 585         cs->dev = NULL;
 586         gigaset_freecs(cs);
 587
 588         gig_dbg(DEBUG_INIT, "Shutdown of HLL done");
 589 }
 590
 591 /*
 592  * Called by the tty driver when the tty line is hung up.
 593  * Wait for I/O to driver to complete and unregister ISDN device.
 594  * This is already done by the close routine, so just call that.
 595  * Called from process context.
 596  */
 597 static int gigaset_tty_hangup(struct tty_struct *tty)
 598 {
 599         gigaset_tty_close(tty);
 600         return 0;
 601 }
 602
 603 /*
 604  * Read on the tty.
 605  * Unused, received data goes only to the Gigaset driver.
 606  */
 607 static ssize_t
 608 gigaset_tty_read(struct tty_struct *tty, struct file *file,
 609                  unsigned char __user *buf, size_t count)
 610 {
 611         return -EAGAIN;
 612 }
 613
 614 /*
 615  * Write on the tty.
 616  * Unused, transmit data comes only from the Gigaset driver.
 617  */
 618 static ssize_t
 619 gigaset_tty_write(struct tty_struct *tty, struct file *file,
 620                   const unsigned char *buf, size_t count)
 621 {
 622         return -EAGAIN;
 623 }
 624
 625 /*
 626  * Ioctl on the tty.
 627  * Called in process context only.
 628  * May be re-entered by multiple ioctl calling threads.
 629  */
 630 static int
 631 gigaset_tty_ioctl(struct tty_struct *tty, struct file *file,
 632                   unsigned int cmd, unsigned long arg)
 633 {
 634         struct cardstate *cs = cs_get(tty);
 635         int rc, val;
 636         int __user *p = (int __user *)arg;
 637
 638         if (!cs)
 639                 return -ENXIO;
 640
 641         switch (cmd) {
 642
 643         case FIONREAD:
 644                 /* unused, always return zero */
 645                 val = 0;
 646                 rc = put_user(val, p);
 647                 break;
 648
 649         case TCFLSH:
 650                 /* flush our buffers and the serial port's buffer */
 651                 switch (arg) {
 652                 case TCIFLUSH:
 653                         /* no own input buffer to flush */
 654                         break;
 655                 case TCIOFLUSH:
 656                 case TCOFLUSH:
 657                         flush_send_queue(cs);
 658                         break;
 659                 }
 660                 /* Pass through */
 661
 662         default:
 663                 /* pass through to underlying serial device */
 664                 rc = n_tty_ioctl_helper(tty, file, cmd, arg);
 665                 break;
 666         }
 667         cs_put(cs);
 668         return rc;
 669 }
 670
 671 /*
 672  * Called by the tty driver when a block of data has been received.
 673  * Will not be re-entered while running but other ldisc functions
 674  * may be called in parallel.
 675  * Can be called from hard interrupt level as well as soft interrupt
 676  * level or mainline.
 677  * Parameters:
 678  *      tty     tty structure
 679  *      buf     buffer containing received characters
 680  *      cflags  buffer containing error flags for received characters (ignored)
 681  *      count   number of received characters
 682  */
 683 static void
 684 gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
 685                     char *cflags, int count)
 686 {
 687         struct cardstate *cs = cs_get(tty);
 688         unsigned tail, head, n;
 689         struct inbuf_t *inbuf;
 690
 691         if (!cs)
 692                 return;
 693         if (!(inbuf = cs->inbuf)) {
 694                 dev_err(cs->dev, "%s: no inbuf\n", __func__);
 695                 cs_put(cs);
 696                 return;
 697         }
 698
 699         tail = inbuf->tail;
 700         head = inbuf->head;
 701         gig_dbg(DEBUG_INTR, "buffer state: %u -> %u, receive %u bytes",
 702                 head, tail, count);
 703
 704         if (head <= tail) {
 705                 /* possible buffer wraparound */
 706                 n = min_t(unsigned, count, RBUFSIZE - tail);
 707                 memcpy(inbuf->data + tail, buf, n);
 708                 tail = (tail + n) % RBUFSIZE;
 709                 buf += n;
 710                 count -= n;
 711         }
 712
 713         if (count > 0) {
 714                 /* tail < head and some data left */
 715                 n = head - tail - 1;
 716                 if (count > n) {
 717                         dev_err(cs->dev,
 718                                 "inbuf overflow, discarding %d bytes\n",
 719                                 count - n);
 720                         count = n;
 721                 }
 722                 memcpy(inbuf->data + tail, buf, count);
 723                 tail += count;
 724         }
 725
 726         gig_dbg(DEBUG_INTR, "setting tail to %u", tail);
 727         inbuf->tail = tail;
 728
 729         /* Everything was received .. Push data into handler */
 730         gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
 731         gigaset_schedule_event(cs);
 732         cs_put(cs);
 733 }
 734
 735 /*
 736  * Called by the tty driver when there's room for more data to send.
 737  */
 738 static void
 739 gigaset_tty_wakeup(struct tty_struct *tty)
 740 {
 741         struct cardstate *cs = cs_get(tty);
 742
 743         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 744         if (!cs)
 745                 return;
 746         tasklet_schedule(&cs->write_tasklet);
 747         cs_put(cs);
 748 }
 749
 750 static struct tty_ldisc_ops gigaset_ldisc = {
 751         .owner          = THIS_MODULE,
 752         .magic          = TTY_LDISC_MAGIC,
 753         .name           = "ser_gigaset",
 754         .open           = gigaset_tty_open,
 755         .close          = gigaset_tty_close,
 756         .hangup         = gigaset_tty_hangup,
 757         .read           = gigaset_tty_read,
 758         .write          = gigaset_tty_write,
 759         .ioctl          = gigaset_tty_ioctl,
 760         .receive_buf    = gigaset_tty_receive,
 761         .write_wakeup   = gigaset_tty_wakeup,
 762 };
 763
 764
 765 /* Initialization / Shutdown */
 766 /* ========================= */
 767
 768 static int __init ser_gigaset_init(void)
 769 {
 770         int rc;
 771
 772         gig_dbg(DEBUG_INIT, "%s", __func__);
 773         if ((rc = platform_driver_register(&device_driver)) != 0) {
 774                 pr_err("error %d registering platform driver\n", rc);
 775                 return rc;
 776         }
 777
 778         /* allocate memory for our driver state and intialize it */
 779         if (!(driver = gigaset_initdriver(GIGASET_MINOR, GIGASET_MINORS,
 780                                           GIGASET_MODULENAME, GIGASET_DEVNAME,
 781                                           &ops, THIS_MODULE)))
 782                 goto error;
 783
 784         if ((rc = tty_register_ldisc(N_GIGASET_M101, &gigaset_ldisc)) != 0) {
 785                 pr_err("error %d registering line discipline\n", rc);
 786                 goto error;
 787         }
 788
 789         return 0;
 790
 791 error:
 792         if (driver) {
 793                 gigaset_freedriver(driver);
 794                 driver = NULL;
 795         }
 796         platform_driver_unregister(&device_driver);
 797         return rc;
 798 }
 799
 800 static void __exit ser_gigaset_exit(void)
 801 {
 802         int rc;
 803
 804         gig_dbg(DEBUG_INIT, "%s", __func__);
 805
 806         if (driver) {
 807                 gigaset_freedriver(driver);
 808                 driver = NULL;
 809         }
 810
 811         if ((rc = tty_unregister_ldisc(N_GIGASET_M101)) != 0)
 812                 pr_err("error %d unregistering line discipline\n", rc);
 813
 814         platform_driver_unregister(&device_driver);
 815 }
 816
 817 module_init(ser_gigaset_init);
 818 module_exit(ser_gigaset_exit);