err.no 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/poll.h>
  20 #include <linux/completion.h>
  21
  22 /* Version Information */
  23 #define DRIVER_AUTHOR "Tilman Schmidt"
  24 #define DRIVER_DESC "Serial Driver for Gigaset 307x using Siemens M101"
  25
  26 #define GIGASET_MINORS     1
  27 #define GIGASET_MINOR      0
  28 #define GIGASET_MODULENAME "ser_gigaset"
  29 #define GIGASET_DEVNAME    "ttyGS"
  30
  31 /* length limit according to Siemens 3070usb-protokoll.doc ch. 2.1 */
  32 #define IF_WRITEBUF 264
  33
  34 MODULE_AUTHOR(DRIVER_AUTHOR);
  35 MODULE_DESCRIPTION(DRIVER_DESC);
  36 MODULE_LICENSE("GPL");
  37 MODULE_ALIAS_LDISC(N_GIGASET_M101);
  38
  39 static int startmode = SM_ISDN;
  40 module_param(startmode, int, S_IRUGO);
  41 MODULE_PARM_DESC(startmode, "initial operation mode");
  42 static int cidmode = 1;
  43 module_param(cidmode, int, S_IRUGO);
  44 MODULE_PARM_DESC(cidmode, "stay in CID mode when idle");
  45
  46 static struct gigaset_driver *driver;
  47
  48 struct ser_cardstate {
  49         struct platform_device  dev;
  50         struct tty_struct       *tty;
  51         atomic_t                refcnt;
  52         struct completion       dead_cmp;
  53 };
  54
  55 static struct platform_driver device_driver = {
  56         .driver = {
  57                 .name = GIGASET_MODULENAME,
  58         },
  59 };
  60
  61 static void flush_send_queue(struct cardstate *);
  62
  63 /* transmit data from current open skb
  64  * result: number of bytes sent or error code < 0
  65  */
  66 static int write_modem(struct cardstate *cs)
  67 {
  68         struct tty_struct *tty = cs->hw.ser->tty;
  69         struct bc_state *bcs = &cs->bcs[0];     /* only one channel */
  70         struct sk_buff *skb = bcs->tx_skb;
  71         int sent = -EOPNOTSUPP;
  72
  73         if (!tty || !tty->driver || !skb)
  74                 return -EINVAL;
  75
  76         if (!skb->len) {
  77                 dev_kfree_skb_any(skb);
  78                 bcs->tx_skb = NULL;
  79                 return -EINVAL;
  80         }
  81
  82         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  83         if (tty->ops->write)
  84                 sent = tty->ops->write(tty, skb->data, skb->len);
  85         gig_dbg(DEBUG_OUTPUT, "write_modem: sent %d", sent);
  86         if (sent < 0) {
  87                 /* error */
  88                 flush_send_queue(cs);
  89                 return sent;
  90         }
  91         skb_pull(skb, sent);
  92         if (!skb->len) {
  93                 /* skb sent completely */
  94                 gigaset_skb_sent(bcs, skb);
  95
  96                 gig_dbg(DEBUG_INTR, "kfree skb (Adr: %lx)!",
  97                         (unsigned long) skb);
  98                 dev_kfree_skb_any(skb);
  99                 bcs->tx_skb = NULL;
 100         }
 101         return sent;
 102 }
 103
 104 /*
 105  * transmit first queued command buffer
 106  * result: number of bytes sent or error code < 0
 107  */
 108 static int send_cb(struct cardstate *cs)
 109 {
 110         struct tty_struct *tty = cs->hw.ser->tty;
 111         struct cmdbuf_t *cb, *tcb;
 112         unsigned long flags;
 113         int sent = 0;
 114
 115         if (!tty || !tty->driver)
 116                 return -EFAULT;
 117
 118         cb = cs->cmdbuf;
 119         if (!cb)
 120                 return 0;       /* nothing to do */
 121
 122         if (cb->len) {
 123                 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 124                 sent = tty->ops->write(tty, cb->buf + cb->offset, cb->len);
 125                 if (sent < 0) {
 126                         /* error */
 127                         gig_dbg(DEBUG_OUTPUT, "send_cb: write error %d", sent);
 128                         flush_send_queue(cs);
 129                         return sent;
 130                 }
 131                 cb->offset += sent;
 132                 cb->len -= sent;
 133                 gig_dbg(DEBUG_OUTPUT, "send_cb: sent %d, left %u, queued %u",
 134                         sent, cb->len, cs->cmdbytes);
 135         }
 136
 137         while (cb && !cb->len) {
 138                 spin_lock_irqsave(&cs->cmdlock, flags);
 139                 cs->cmdbytes -= cs->curlen;
 140                 tcb = cb;
 141                 cs->cmdbuf = cb = cb->next;
 142                 if (cb) {
 143                         cb->prev = NULL;
 144                         cs->curlen = cb->len;
 145                 } else {
 146                         cs->lastcmdbuf = NULL;
 147                         cs->curlen = 0;
 148                 }
 149                 spin_unlock_irqrestore(&cs->cmdlock, flags);
 150
 151                 if (tcb->wake_tasklet)
 152                         tasklet_schedule(tcb->wake_tasklet);
 153                 kfree(tcb);
 154         }
 155         return sent;
 156 }
 157
 158 /*
 159  * send queue tasklet
 160  * If there is already a skb opened, put data to the transfer buffer
 161  * by calling "write_modem".
 162  * Otherwise take a new skb out of the queue.
 163  */
 164 static void gigaset_modem_fill(unsigned long data)
 165 {
 166         struct cardstate *cs = (struct cardstate *) data;
 167         struct bc_state *bcs;
 168         int sent = 0;
 169
 170         if (!cs || !(bcs = cs->bcs)) {
 171                 gig_dbg(DEBUG_OUTPUT, "%s: no cardstate", __func__);
 172                 return;
 173         }
 174         if (!bcs->tx_skb) {
 175                 /* no skb is being sent; send command if any */
 176                 sent = send_cb(cs);
 177                 gig_dbg(DEBUG_OUTPUT, "%s: send_cb -> %d", __func__, sent);
 178                 if (sent)
 179                         /* something sent or error */
 180                         return;
 181
 182                 /* no command to send; get skb */
 183                 if (!(bcs->tx_skb = skb_dequeue(&bcs->squeue)))
 184                         /* no skb either, nothing to do */
 185                         return;
 186
 187                 gig_dbg(DEBUG_INTR, "Dequeued skb (Adr: %lx)",
 188                         (unsigned long) bcs->tx_skb);
 189         }
 190
 191         /* send skb */
 192         gig_dbg(DEBUG_OUTPUT, "%s: tx_skb", __func__);
 193         if (write_modem(cs) < 0)
 194                 gig_dbg(DEBUG_OUTPUT, "%s: write_modem failed", __func__);
 195 }
 196
 197 /*
 198  * throw away all data queued for sending
 199  */
 200 static void flush_send_queue(struct cardstate *cs)
 201 {
 202         struct sk_buff *skb;
 203         struct cmdbuf_t *cb;
 204         unsigned long flags;
 205
 206         /* command queue */
 207         spin_lock_irqsave(&cs->cmdlock, flags);
 208         while ((cb = cs->cmdbuf) != NULL) {
 209                 cs->cmdbuf = cb->next;
 210                 if (cb->wake_tasklet)
 211                         tasklet_schedule(cb->wake_tasklet);
 212                 kfree(cb);
 213         }
 214         cs->cmdbuf = cs->lastcmdbuf = NULL;
 215         cs->cmdbytes = cs->curlen = 0;
 216         spin_unlock_irqrestore(&cs->cmdlock, flags);
 217
 218         /* data queue */
 219         if (cs->bcs->tx_skb)
 220                 dev_kfree_skb_any(cs->bcs->tx_skb);
 221         while ((skb = skb_dequeue(&cs->bcs->squeue)) != NULL)
 222                 dev_kfree_skb_any(skb);
 223 }
 224
 225
 226 /* Gigaset Driver Interface */
 227 /* ======================== */
 228
 229 /*
 230  * queue an AT command string for transmission to the Gigaset device
 231  * parameters:
 232  *      cs              controller state structure
 233  *      buf             buffer containing the string to send
 234  *      len             number of characters to send
 235  *      wake_tasklet    tasklet to run when transmission is complete, or NULL
 236  * return value:
 237  *      number of bytes queued, or error code < 0
 238  */
 239 static int gigaset_write_cmd(struct cardstate *cs, const unsigned char *buf,
 240                              int len, struct tasklet_struct *wake_tasklet)
 241 {
 242         struct cmdbuf_t *cb;
 243         unsigned long flags;
 244
 245         gigaset_dbg_buffer(cs->mstate != MS_LOCKED ?
 246                              DEBUG_TRANSCMD : DEBUG_LOCKCMD,
 247                            "CMD Transmit", len, buf);
 248
 249         if (len <= 0)
 250                 return 0;
 251
 252         if (!(cb = kmalloc(sizeof(struct cmdbuf_t) + len, GFP_ATOMIC))) {
 253                 dev_err(cs->dev, "%s: out of memory!\n", __func__);
 254                 return -ENOMEM;
 255         }
 256
 257         memcpy(cb->buf, buf, len);
 258         cb->len = len;
 259         cb->offset = 0;
 260         cb->next = NULL;
 261         cb->wake_tasklet = wake_tasklet;
 262
 263         spin_lock_irqsave(&cs->cmdlock, flags);
 264         cb->prev = cs->lastcmdbuf;
 265         if (cs->lastcmdbuf)
 266                 cs->lastcmdbuf->next = cb;
 267         else {
 268                 cs->cmdbuf = cb;
 269                 cs->curlen = len;
 270         }
 271         cs->cmdbytes += len;
 272         cs->lastcmdbuf = cb;
 273         spin_unlock_irqrestore(&cs->cmdlock, flags);
 274
 275         spin_lock_irqsave(&cs->lock, flags);
 276         if (cs->connected)
 277                 tasklet_schedule(&cs->write_tasklet);
 278         spin_unlock_irqrestore(&cs->lock, flags);
 279         return len;
 280 }
 281
 282 /*
 283  * tty_driver.write_room interface routine
 284  * return number of characters the driver will accept to be written
 285  * parameter:
 286  *      controller state structure
 287  * return value:
 288  *      number of characters
 289  */
 290 static int gigaset_write_room(struct cardstate *cs)
 291 {
 292         unsigned bytes;
 293
 294         bytes = cs->cmdbytes;
 295         return bytes < IF_WRITEBUF ? IF_WRITEBUF - bytes : 0;
 296 }
 297
 298 /*
 299  * tty_driver.chars_in_buffer interface routine
 300  * return number of characters waiting to be sent
 301  * parameter:
 302  *      controller state structure
 303  * return value:
 304  *      number of characters
 305  */
 306 static int gigaset_chars_in_buffer(struct cardstate *cs)
 307 {
 308         return cs->cmdbytes;
 309 }
 310
 311 /*
 312  * implementation of ioctl(GIGASET_BRKCHARS)
 313  * parameter:
 314  *      controller state structure
 315  * return value:
 316  *      -EINVAL (unimplemented function)
 317  */
 318 static int gigaset_brkchars(struct cardstate *cs, const unsigned char buf[6])
 319 {
 320         /* not implemented */
 321         return -EINVAL;
 322 }
 323
 324 /*
 325  * Open B channel
 326  * Called by "do_action" in ev-layer.c
 327  */
 328 static int gigaset_init_bchannel(struct bc_state *bcs)
 329 {
 330         /* nothing to do for M10x */
 331         gigaset_bchannel_up(bcs);
 332         return 0;
 333 }
 334
 335 /*
 336  * Close B channel
 337  * Called by "do_action" in ev-layer.c
 338  */
 339 static int gigaset_close_bchannel(struct bc_state *bcs)
 340 {
 341         /* nothing to do for M10x */
 342         gigaset_bchannel_down(bcs);
 343         return 0;
 344 }
 345
 346 /*
 347  * Set up B channel structure
 348  * This is called by "gigaset_initcs" in common.c
 349  */
 350 static int gigaset_initbcshw(struct bc_state *bcs)
 351 {
 352         /* unused */
 353         bcs->hw.ser = NULL;
 354         return 1;
 355 }
 356
 357 /*
 358  * Free B channel structure
 359  * Called by "gigaset_freebcs" in common.c
 360  */
 361 static int gigaset_freebcshw(struct bc_state *bcs)
 362 {
 363         /* unused */
 364         return 1;
 365 }
 366
 367 /*
 368  * Reinitialize B channel structure
 369  * This is called by "bcs_reinit" in common.c
 370  */
 371 static void gigaset_reinitbcshw(struct bc_state *bcs)
 372 {
 373         /* nothing to do for M10x */
 374 }
 375
 376 /*
 377  * Free hardware specific device data
 378  * This will be called by "gigaset_freecs" in common.c
 379  */
 380 static void gigaset_freecshw(struct cardstate *cs)
 381 {
 382         tasklet_kill(&cs->write_tasklet);
 383         if (!cs->hw.ser)
 384                 return;
 385         dev_set_drvdata(&cs->hw.ser->dev.dev, NULL);
 386         platform_device_unregister(&cs->hw.ser->dev);
 387         kfree(cs->hw.ser);
 388         cs->hw.ser = NULL;
 389 }
 390
 391 static void gigaset_device_release(struct device *dev)
 392 {
 393         struct platform_device *pdev =
 394                 container_of(dev, struct platform_device, dev);
 395
 396         /* adapted from platform_device_release() in drivers/base/platform.c */
 397         //FIXME is this actually necessary?
 398         kfree(dev->platform_data);
 399         kfree(pdev->resource);
 400 }
 401
 402 /*
 403  * Set up hardware specific device data
 404  * This is called by "gigaset_initcs" in common.c
 405  */
 406 static int gigaset_initcshw(struct cardstate *cs)
 407 {
 408         int rc;
 409
 410         if (!(cs->hw.ser = kzalloc(sizeof(struct ser_cardstate), GFP_KERNEL))) {
 411                 err("%s: out of memory!", __func__);
 412                 return 0;
 413         }
 414
 415         cs->hw.ser->dev.name = GIGASET_MODULENAME;
 416         cs->hw.ser->dev.id = cs->minor_index;
 417         cs->hw.ser->dev.dev.release = gigaset_device_release;
 418         if ((rc = platform_device_register(&cs->hw.ser->dev)) != 0) {
 419                 err("error %d registering platform device", rc);
 420                 kfree(cs->hw.ser);
 421                 cs->hw.ser = NULL;
 422                 return 0;
 423         }
 424         dev_set_drvdata(&cs->hw.ser->dev.dev, cs);
 425
 426         tasklet_init(&cs->write_tasklet,
 427                      &gigaset_modem_fill, (unsigned long) cs);
 428         return 1;
 429 }
 430
 431 /*
 432  * set modem control lines
 433  * Parameters:
 434  *      card state structure
 435  *      modem control line state ([TIOCM_DTR]|[TIOCM_RTS])
 436  * Called by "gigaset_start" and "gigaset_enterconfigmode" in common.c
 437  * and by "if_lock" and "if_termios" in interface.c
 438  */
 439 static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state, unsigned new_state)
 440 {
 441         struct tty_struct *tty = cs->hw.ser->tty;
 442         unsigned int set, clear;
 443
 444         if (!tty || !tty->driver || !tty->ops->tiocmset)
 445                 return -EINVAL;
 446         set = new_state & ~old_state;
 447         clear = old_state & ~new_state;
 448         if (!set && !clear)
 449                 return 0;
 450         gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
 451         return tty->ops->tiocmset(tty, NULL, set, clear);
 452 }
 453
 454 static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
 455 {
 456         return -EINVAL;
 457 }
 458
 459 static int gigaset_set_line_ctrl(struct cardstate *cs, unsigned cflag)
 460 {
 461         return -EINVAL;
 462 }
 463
 464 static const struct gigaset_ops ops = {
 465         gigaset_write_cmd,
 466         gigaset_write_room,
 467         gigaset_chars_in_buffer,
 468         gigaset_brkchars,
 469         gigaset_init_bchannel,
 470         gigaset_close_bchannel,
 471         gigaset_initbcshw,
 472         gigaset_freebcshw,
 473         gigaset_reinitbcshw,
 474         gigaset_initcshw,
 475         gigaset_freecshw,
 476         gigaset_set_modem_ctrl,
 477         gigaset_baud_rate,
 478         gigaset_set_line_ctrl,
 479         gigaset_m10x_send_skb,  /* asyncdata.c */
 480         gigaset_m10x_input,     /* asyncdata.c */
 481 };
 482
 483
 484 /* Line Discipline Interface */
 485 /* ========================= */
 486
 487 /* helper functions for cardstate refcounting */
 488 static struct cardstate *cs_get(struct tty_struct *tty)
 489 {
 490         struct cardstate *cs = tty->disc_data;
 491
 492         if (!cs || !cs->hw.ser) {
 493                 gig_dbg(DEBUG_ANY, "%s: no cardstate", __func__);
 494                 return NULL;
 495         }
 496         atomic_inc(&cs->hw.ser->refcnt);
 497         return cs;
 498 }
 499
 500 static void cs_put(struct cardstate *cs)
 501 {
 502         if (atomic_dec_and_test(&cs->hw.ser->refcnt))
 503                 complete(&cs->hw.ser->dead_cmp);
 504 }
 505
 506 /*
 507  * Called by the tty driver when the line discipline is pushed onto the tty.
 508  * Called in process context.
 509  */
 510 static int
 511 gigaset_tty_open(struct tty_struct *tty)
 512 {
 513         struct cardstate *cs;
 514
 515         gig_dbg(DEBUG_INIT, "Starting HLL for Gigaset M101");
 516
 517         info(DRIVER_AUTHOR);
 518         info(DRIVER_DESC);
 519
 520         if (!driver) {
 521                 err("%s: no driver structure", __func__);
 522                 return -ENODEV;
 523         }
 524
 525         /* allocate memory for our device state and intialize it */
 526         if (!(cs = gigaset_initcs(driver, 1, 1, 0, cidmode,
 527                                   GIGASET_MODULENAME)))
 528                 goto error;
 529
 530         cs->dev = &cs->hw.ser->dev.dev;
 531         cs->hw.ser->tty = tty;
 532         atomic_set(&cs->hw.ser->refcnt, 1);
 533         init_completion(&cs->hw.ser->dead_cmp);
 534
 535         tty->disc_data = cs;
 536
 537         /* OK.. Initialization of the datastructures and the HW is done.. Now
 538          * startup system and notify the LL that we are ready to run
 539          */
 540         if (startmode == SM_LOCKED)
 541                 cs->mstate = MS_LOCKED;
 542         if (!gigaset_start(cs)) {
 543                 tasklet_kill(&cs->write_tasklet);
 544                 goto error;
 545         }
 546
 547         gig_dbg(DEBUG_INIT, "Startup of HLL done");
 548         return 0;
 549
 550 error:
 551         gig_dbg(DEBUG_INIT, "Startup of HLL failed");
 552         tty->disc_data = NULL;
 553         gigaset_freecs(cs);
 554         return -ENODEV;
 555 }
 556
 557 /*
 558  * Called by the tty driver when the line discipline is removed.
 559  * Called from process context.
 560  */
 561 static void
 562 gigaset_tty_close(struct tty_struct *tty)
 563 {
 564         struct cardstate *cs = tty->disc_data;
 565
 566         gig_dbg(DEBUG_INIT, "Stopping HLL for Gigaset M101");
 567
 568         if (!cs) {
 569                 gig_dbg(DEBUG_INIT, "%s: no cardstate", __func__);
 570                 return;
 571         }
 572
 573         /* prevent other callers from entering ldisc methods */
 574         tty->disc_data = NULL;
 575
 576         if (!cs->hw.ser)
 577                 err("%s: no hw cardstate", __func__);
 578         else {
 579                 /* wait for running methods to finish */
 580                 if (!atomic_dec_and_test(&cs->hw.ser->refcnt))
 581                         wait_for_completion(&cs->hw.ser->dead_cmp);
 582         }
 583
 584         /* stop operations */
 585         gigaset_stop(cs);
 586         tasklet_kill(&cs->write_tasklet);
 587         flush_send_queue(cs);
 588         cs->dev = NULL;
 589         gigaset_freecs(cs);
 590
 591         gig_dbg(DEBUG_INIT, "Shutdown of HLL done");
 592 }
 593
 594 /*
 595  * Called by the tty driver when the tty line is hung up.
 596  * Wait for I/O to driver to complete and unregister ISDN device.
 597  * This is already done by the close routine, so just call that.
 598  * Called from process context.
 599  */
 600 static int gigaset_tty_hangup(struct tty_struct *tty)
 601 {
 602         gigaset_tty_close(tty);
 603         return 0;
 604 }
 605
 606 /*
 607  * Read on the tty.
 608  * Unused, received data goes only to the Gigaset driver.
 609  */
 610 static ssize_t
 611 gigaset_tty_read(struct tty_struct *tty, struct file *file,
 612                  unsigned char __user *buf, size_t count)
 613 {
 614         return -EAGAIN;
 615 }
 616
 617 /*
 618  * Write on the tty.
 619  * Unused, transmit data comes only from the Gigaset driver.
 620  */
 621 static ssize_t
 622 gigaset_tty_write(struct tty_struct *tty, struct file *file,
 623                   const unsigned char *buf, size_t count)
 624 {
 625         return -EAGAIN;
 626 }
 627
 628 /*
 629  * Ioctl on the tty.
 630  * Called in process context only.
 631  * May be re-entered by multiple ioctl calling threads.
 632  */
 633 static int
 634 gigaset_tty_ioctl(struct tty_struct *tty, struct file *file,
 635                   unsigned int cmd, unsigned long arg)
 636 {
 637         struct cardstate *cs = cs_get(tty);
 638         int rc, val;
 639         int __user *p = (int __user *)arg;
 640
 641         if (!cs)
 642                 return -ENXIO;
 643
 644         switch (cmd) {
 645         case TCGETS:
 646         case TCGETA:
 647                 /* pass through to underlying serial device */
 648                 rc = n_tty_ioctl(tty, file, cmd, arg);
 649                 break;
 650
 651         case TCFLSH:
 652                 /* flush our buffers and the serial port's buffer */
 653                 switch (arg) {
 654                 case TCIFLUSH:
 655                         /* no own input buffer to flush */
 656                         break;
 657                 case TCIOFLUSH:
 658                 case TCOFLUSH:
 659                         flush_send_queue(cs);
 660                         break;
 661                 }
 662                 /* flush the serial port's buffer */
 663                 rc = n_tty_ioctl(tty, file, cmd, arg);
 664                 break;
 665
 666         case FIONREAD:
 667                 /* unused, always return zero */
 668                 val = 0;
 669                 rc = put_user(val, p);
 670                 break;
 671
 672         default:
 673                 rc = -ENOIOCTLCMD;
 674         }
 675
 676         cs_put(cs);
 677         return rc;
 678 }
 679
 680 /*
 681  * Poll on the tty.
 682  * Unused, always return zero.
 683  */
 684 static unsigned int
 685 gigaset_tty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
 686 {
 687         return 0;
 688 }
 689
 690 /*
 691  * Called by the tty driver when a block of data has been received.
 692  * Will not be re-entered while running but other ldisc functions
 693  * may be called in parallel.
 694  * Can be called from hard interrupt level as well as soft interrupt
 695  * level or mainline.
 696  * Parameters:
 697  *      tty     tty structure
 698  *      buf     buffer containing received characters
 699  *      cflags  buffer containing error flags for received characters (ignored)
 700  *      count   number of received characters
 701  */
 702 static void
 703 gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
 704                     char *cflags, int count)
 705 {
 706         struct cardstate *cs = cs_get(tty);
 707         unsigned tail, head, n;
 708         struct inbuf_t *inbuf;
 709
 710         if (!cs)
 711                 return;
 712         if (!(inbuf = cs->inbuf)) {
 713                 dev_err(cs->dev, "%s: no inbuf\n", __func__);
 714                 cs_put(cs);
 715                 return;
 716         }
 717
 718         tail = inbuf->tail;
 719         head = inbuf->head;
 720         gig_dbg(DEBUG_INTR, "buffer state: %u -> %u, receive %u bytes",
 721                 head, tail, count);
 722
 723         if (head <= tail) {
 724                 /* possible buffer wraparound */
 725                 n = min_t(unsigned, count, RBUFSIZE - tail);
 726                 memcpy(inbuf->data + tail, buf, n);
 727                 tail = (tail + n) % RBUFSIZE;
 728                 buf += n;
 729                 count -= n;
 730         }
 731
 732         if (count > 0) {
 733                 /* tail < head and some data left */
 734                 n = head - tail - 1;
 735                 if (count > n) {
 736                         dev_err(cs->dev,
 737                                 "inbuf overflow, discarding %d bytes\n",
 738                                 count - n);
 739                         count = n;
 740                 }
 741                 memcpy(inbuf->data + tail, buf, count);
 742                 tail += count;
 743         }
 744
 745         gig_dbg(DEBUG_INTR, "setting tail to %u", tail);
 746         inbuf->tail = tail;
 747
 748         /* Everything was received .. Push data into handler */
 749         gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
 750         gigaset_schedule_event(cs);
 751         cs_put(cs);
 752 }
 753
 754 /*
 755  * Called by the tty driver when there's room for more data to send.
 756  */
 757 static void
 758 gigaset_tty_wakeup(struct tty_struct *tty)
 759 {
 760         struct cardstate *cs = cs_get(tty);
 761
 762         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 763         if (!cs)
 764                 return;
 765         tasklet_schedule(&cs->write_tasklet);
 766         cs_put(cs);
 767 }
 768
 769 static struct tty_ldisc gigaset_ldisc = {
 770         .owner          = THIS_MODULE,
 771         .magic          = TTY_LDISC_MAGIC,
 772         .name           = "ser_gigaset",
 773         .open           = gigaset_tty_open,
 774         .close          = gigaset_tty_close,
 775         .hangup         = gigaset_tty_hangup,
 776         .read           = gigaset_tty_read,
 777         .write          = gigaset_tty_write,
 778         .ioctl          = gigaset_tty_ioctl,
 779         .poll           = gigaset_tty_poll,
 780         .receive_buf    = gigaset_tty_receive,
 781         .write_wakeup   = gigaset_tty_wakeup,
 782 };
 783
 784
 785 /* Initialization / Shutdown */
 786 /* ========================= */
 787
 788 static int __init ser_gigaset_init(void)
 789 {
 790         int rc;
 791
 792         gig_dbg(DEBUG_INIT, "%s", __func__);
 793         if ((rc = platform_driver_register(&device_driver)) != 0) {
 794                 err("error %d registering platform driver", rc);
 795                 return rc;
 796         }
 797
 798         /* allocate memory for our driver state and intialize it */
 799         if (!(driver = gigaset_initdriver(GIGASET_MINOR, GIGASET_MINORS,
 800                                           GIGASET_MODULENAME, GIGASET_DEVNAME,
 801                                           &ops, THIS_MODULE)))
 802                 goto error;
 803
 804         if ((rc = tty_register_ldisc(N_GIGASET_M101, &gigaset_ldisc)) != 0) {
 805                 err("error %d registering line discipline", rc);
 806                 goto error;
 807         }
 808
 809         return 0;
 810
 811 error:
 812         if (driver) {
 813                 gigaset_freedriver(driver);
 814                 driver = NULL;
 815         }
 816         platform_driver_unregister(&device_driver);
 817         return rc;
 818 }
 819
 820 static void __exit ser_gigaset_exit(void)
 821 {
 822         int rc;
 823
 824         gig_dbg(DEBUG_INIT, "%s", __func__);
 825
 826         if (driver) {
 827                 gigaset_freedriver(driver);
 828                 driver = NULL;
 829         }
 830
 831         if ((rc = tty_unregister_ldisc(N_GIGASET_M101)) != 0)
 832                 err("error %d unregistering line discipline", rc);
 833
 834         platform_driver_unregister(&device_driver);
 835 }
 836
 837 module_init(ser_gigaset_init);
 838 module_exit(ser_gigaset_exit);