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         dev_set_drvdata(&cs->hw.ser->dev.dev, NULL);
 375         platform_device_unregister(&cs->hw.ser->dev);
 376         kfree(cs->hw.ser);
 377         cs->hw.ser = NULL;
 378 }
 379
 380 static void gigaset_device_release(struct device *dev)
 381 {
 382         struct platform_device *pdev = to_platform_device(dev);
 383
 384         /* adapted from platform_device_release() in drivers/base/platform.c */
 385         kfree(dev->platform_data);
 386         kfree(pdev->resource);
 387 }
 388
 389 /*
 390  * Set up hardware specific device data
 391  * This is called by "gigaset_initcs" in common.c
 392  */
 393 static int gigaset_initcshw(struct cardstate *cs)
 394 {
 395         int rc;
 396         struct ser_cardstate *scs;
 397
 398         scs = kzalloc(sizeof(struct ser_cardstate), GFP_KERNEL);
 399         if (!scs) {
 400                 pr_err("out of memory\n");
 401                 return 0;
 402         }
 403         cs->hw.ser = scs;
 404
 405         cs->hw.ser->dev.name = GIGASET_MODULENAME;
 406         cs->hw.ser->dev.id = cs->minor_index;
 407         cs->hw.ser->dev.dev.release = gigaset_device_release;
 408         rc = platform_device_register(&cs->hw.ser->dev);
 409         if (rc != 0) {
 410                 pr_err("error %d registering platform device\n", rc);
 411                 kfree(cs->hw.ser);
 412                 cs->hw.ser = NULL;
 413                 return 0;
 414         }
 415         dev_set_drvdata(&cs->hw.ser->dev.dev, cs);
 416
 417         tasklet_init(&cs->write_tasklet,
 418                      gigaset_modem_fill, (unsigned long) cs);
 419         return 1;
 420 }
 421
 422 /*
 423  * set modem control lines
 424  * Parameters:
 425  *      card state structure
 426  *      modem control line state ([TIOCM_DTR]|[TIOCM_RTS])
 427  * Called by "gigaset_start" and "gigaset_enterconfigmode" in common.c
 428  * and by "if_lock" and "if_termios" in interface.c
 429  */
 430 static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state,
 431                                   unsigned new_state)
 432 {
 433         struct tty_struct *tty = cs->hw.ser->tty;
 434         unsigned int set, clear;
 435
 436         if (!tty || !tty->driver || !tty->ops->tiocmset)
 437                 return -EINVAL;
 438         set = new_state & ~old_state;
 439         clear = old_state & ~new_state;
 440         if (!set && !clear)
 441                 return 0;
 442         gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
 443         return tty->ops->tiocmset(tty, set, clear);
 444 }
 445
 446 static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)
 447 {
 448         return -EINVAL;
 449 }
 450
 451 static int gigaset_set_line_ctrl(struct cardstate *cs, unsigned cflag)
 452 {
 453         return -EINVAL;
 454 }
 455
 456 static const struct gigaset_ops ops = {
 457         gigaset_write_cmd,
 458         gigaset_write_room,
 459         gigaset_chars_in_buffer,
 460         gigaset_brkchars,
 461         gigaset_init_bchannel,
 462         gigaset_close_bchannel,
 463         gigaset_initbcshw,
 464         gigaset_freebcshw,
 465         gigaset_reinitbcshw,
 466         gigaset_initcshw,
 467         gigaset_freecshw,
 468         gigaset_set_modem_ctrl,
 469         gigaset_baud_rate,
 470         gigaset_set_line_ctrl,
 471         gigaset_m10x_send_skb,  /* asyncdata.c */
 472         gigaset_m10x_input,     /* asyncdata.c */
 473 };
 474
 475
 476 /* Line Discipline Interface */
 477 /* ========================= */
 478
 479 /* helper functions for cardstate refcounting */
 480 static struct cardstate *cs_get(struct tty_struct *tty)
 481 {
 482         struct cardstate *cs = tty->disc_data;
 483
 484         if (!cs || !cs->hw.ser) {
 485                 gig_dbg(DEBUG_ANY, "%s: no cardstate", __func__);
 486                 return NULL;
 487         }
 488         atomic_inc(&cs->hw.ser->refcnt);
 489         return cs;
 490 }
 491
 492 static void cs_put(struct cardstate *cs)
 493 {
 494         if (atomic_dec_and_test(&cs->hw.ser->refcnt))
 495                 complete(&cs->hw.ser->dead_cmp);
 496 }
 497
 498 /*
 499  * Called by the tty driver when the line discipline is pushed onto the tty.
 500  * Called in process context.
 501  */
 502 static int
 503 gigaset_tty_open(struct tty_struct *tty)
 504 {
 505         struct cardstate *cs;
 506
 507         gig_dbg(DEBUG_INIT, "Starting HLL for Gigaset M101");
 508
 509         pr_info(DRIVER_DESC "\n");
 510
 511         if (!driver) {
 512                 pr_err("%s: no driver structure\n", __func__);
 513                 return -ENODEV;
 514         }
 515
 516         /* allocate memory for our device state and initialize it */
 517         cs = gigaset_initcs(driver, 1, 1, 0, cidmode, GIGASET_MODULENAME);
 518         if (!cs)
 519                 goto error;
 520
 521         cs->dev = &cs->hw.ser->dev.dev;
 522         cs->hw.ser->tty = tty;
 523         atomic_set(&cs->hw.ser->refcnt, 1);
 524         init_completion(&cs->hw.ser->dead_cmp);
 525
 526         tty->disc_data = cs;
 527
 528         /* OK.. Initialization of the datastructures and the HW is done.. Now
 529          * startup system and notify the LL that we are ready to run
 530          */
 531         if (startmode == SM_LOCKED)
 532                 cs->mstate = MS_LOCKED;
 533         if (!gigaset_start(cs)) {
 534                 tasklet_kill(&cs->write_tasklet);
 535                 goto error;
 536         }
 537
 538         gig_dbg(DEBUG_INIT, "Startup of HLL done");
 539         return 0;
 540
 541 error:
 542         gig_dbg(DEBUG_INIT, "Startup of HLL failed");
 543         tty->disc_data = NULL;
 544         gigaset_freecs(cs);
 545         return -ENODEV;
 546 }
 547
 548 /*
 549  * Called by the tty driver when the line discipline is removed.
 550  * Called from process context.
 551  */
 552 static void
 553 gigaset_tty_close(struct tty_struct *tty)
 554 {
 555         struct cardstate *cs = tty->disc_data;
 556
 557         gig_dbg(DEBUG_INIT, "Stopping HLL for Gigaset M101");
 558
 559         if (!cs) {
 560                 gig_dbg(DEBUG_INIT, "%s: no cardstate", __func__);
 561                 return;
 562         }
 563
 564         /* prevent other callers from entering ldisc methods */
 565         tty->disc_data = NULL;
 566
 567         if (!cs->hw.ser)
 568                 pr_err("%s: no hw cardstate\n", __func__);
 569         else {
 570                 /* wait for running methods to finish */
 571                 if (!atomic_dec_and_test(&cs->hw.ser->refcnt))
 572                         wait_for_completion(&cs->hw.ser->dead_cmp);
 573         }
 574
 575         /* stop operations */
 576         gigaset_stop(cs);
 577         tasklet_kill(&cs->write_tasklet);
 578         flush_send_queue(cs);
 579         cs->dev = NULL;
 580         gigaset_freecs(cs);
 581
 582         gig_dbg(DEBUG_INIT, "Shutdown of HLL done");
 583 }
 584
 585 /*
 586  * Called by the tty driver when the tty line is hung up.
 587  * Wait for I/O to driver to complete and unregister ISDN device.
 588  * This is already done by the close routine, so just call that.
 589  * Called from process context.
 590  */
 591 static int gigaset_tty_hangup(struct tty_struct *tty)
 592 {
 593         gigaset_tty_close(tty);
 594         return 0;
 595 }
 596
 597 /*
 598  * Read on the tty.
 599  * Unused, received data goes only to the Gigaset driver.
 600  */
 601 static ssize_t
 602 gigaset_tty_read(struct tty_struct *tty, struct file *file,
 603                  unsigned char __user *buf, size_t count)
 604 {
 605         return -EAGAIN;
 606 }
 607
 608 /*
 609  * Write on the tty.
 610  * Unused, transmit data comes only from the Gigaset driver.
 611  */
 612 static ssize_t
 613 gigaset_tty_write(struct tty_struct *tty, struct file *file,
 614                   const unsigned char *buf, size_t count)
 615 {
 616         return -EAGAIN;
 617 }
 618
 619 /*
 620  * Ioctl on the tty.
 621  * Called in process context only.
 622  * May be re-entered by multiple ioctl calling threads.
 623  */
 624 static int
 625 gigaset_tty_ioctl(struct tty_struct *tty, struct file *file,
 626                   unsigned int cmd, unsigned long arg)
 627 {
 628         struct cardstate *cs = cs_get(tty);
 629         int rc, val;
 630         int __user *p = (int __user *)arg;
 631
 632         if (!cs)
 633                 return -ENXIO;
 634
 635         switch (cmd) {
 636
 637         case FIONREAD:
 638                 /* unused, always return zero */
 639                 val = 0;
 640                 rc = put_user(val, p);
 641                 break;
 642
 643         case TCFLSH:
 644                 /* flush our buffers and the serial port's buffer */
 645                 switch (arg) {
 646                 case TCIFLUSH:
 647                         /* no own input buffer to flush */
 648                         break;
 649                 case TCIOFLUSH:
 650                 case TCOFLUSH:
 651                         flush_send_queue(cs);
 652                         break;
 653                 }
 654                 /* Pass through */
 655
 656         default:
 657                 /* pass through to underlying serial device */
 658                 rc = n_tty_ioctl_helper(tty, file, cmd, arg);
 659                 break;
 660         }
 661         cs_put(cs);
 662         return rc;
 663 }
 664
 665 /*
 666  * Called by the tty driver when a block of data has been received.
 667  * Will not be re-entered while running but other ldisc functions
 668  * may be called in parallel.
 669  * Can be called from hard interrupt level as well as soft interrupt
 670  * level or mainline.
 671  * Parameters:
 672  *      tty     tty structure
 673  *      buf     buffer containing received characters
 674  *      cflags  buffer containing error flags for received characters (ignored)
 675  *      count   number of received characters
 676  */
 677 static void
 678 gigaset_tty_receive(struct tty_struct *tty, const unsigned char *buf,
 679                     char *cflags, int count)
 680 {
 681         struct cardstate *cs = cs_get(tty);
 682         unsigned tail, head, n;
 683         struct inbuf_t *inbuf;
 684
 685         if (!cs)
 686                 return;
 687         inbuf = cs->inbuf;
 688         if (!inbuf) {
 689                 dev_err(cs->dev, "%s: no inbuf\n", __func__);
 690                 cs_put(cs);
 691                 return;
 692         }
 693
 694         tail = inbuf->tail;
 695         head = inbuf->head;
 696         gig_dbg(DEBUG_INTR, "buffer state: %u -> %u, receive %u bytes",
 697                 head, tail, count);
 698
 699         if (head <= tail) {
 700                 /* possible buffer wraparound */
 701                 n = min_t(unsigned, count, RBUFSIZE - tail);
 702                 memcpy(inbuf->data + tail, buf, n);
 703                 tail = (tail + n) % RBUFSIZE;
 704                 buf += n;
 705                 count -= n;
 706         }
 707
 708         if (count > 0) {
 709                 /* tail < head and some data left */
 710                 n = head - tail - 1;
 711                 if (count > n) {
 712                         dev_err(cs->dev,
 713                                 "inbuf overflow, discarding %d bytes\n",
 714                                 count - n);
 715                         count = n;
 716                 }
 717                 memcpy(inbuf->data + tail, buf, count);
 718                 tail += count;
 719         }
 720
 721         gig_dbg(DEBUG_INTR, "setting tail to %u", tail);
 722         inbuf->tail = tail;
 723
 724         /* Everything was received .. Push data into handler */
 725         gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
 726         gigaset_schedule_event(cs);
 727         cs_put(cs);
 728 }
 729
 730 /*
 731  * Called by the tty driver when there's room for more data to send.
 732  */
 733 static void
 734 gigaset_tty_wakeup(struct tty_struct *tty)
 735 {
 736         struct cardstate *cs = cs_get(tty);
 737
 738         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 739         if (!cs)
 740                 return;
 741         tasklet_schedule(&cs->write_tasklet);
 742         cs_put(cs);
 743 }
 744
 745 static struct tty_ldisc_ops gigaset_ldisc = {
 746         .owner          = THIS_MODULE,
 747         .magic          = TTY_LDISC_MAGIC,
 748         .name           = "ser_gigaset",
 749         .open           = gigaset_tty_open,
 750         .close          = gigaset_tty_close,
 751         .hangup         = gigaset_tty_hangup,
 752         .read           = gigaset_tty_read,
 753         .write          = gigaset_tty_write,
 754         .ioctl          = gigaset_tty_ioctl,
 755         .receive_buf    = gigaset_tty_receive,
 756         .write_wakeup   = gigaset_tty_wakeup,
 757 };
 758
 759
 760 /* Initialization / Shutdown */
 761 /* ========================= */
 762
 763 static int __init ser_gigaset_init(void)
 764 {
 765         int rc;
 766
 767         gig_dbg(DEBUG_INIT, "%s", __func__);
 768         rc = platform_driver_register(&device_driver);
 769         if (rc != 0) {
 770                 pr_err("error %d registering platform driver\n", rc);
 771                 return rc;
 772         }
 773
 774         /* allocate memory for our driver state and initialize it */
 775         driver = gigaset_initdriver(GIGASET_MINOR, GIGASET_MINORS,
 776                                           GIGASET_MODULENAME, GIGASET_DEVNAME,
 777                                           &ops, THIS_MODULE);
 778         if (!driver)
 779                 goto error;
 780
 781         rc = tty_register_ldisc(N_GIGASET_M101, &gigaset_ldisc);
 782         if (rc != 0) {
 783                 pr_err("error %d registering line discipline\n", rc);
 784                 goto error;
 785         }
 786
 787         return 0;
 788
 789 error:
 790         if (driver) {
 791                 gigaset_freedriver(driver);
 792                 driver = NULL;
 793         }
 794         platform_driver_unregister(&device_driver);
 795         return rc;
 796 }
 797
 798 static void __exit ser_gigaset_exit(void)
 799 {
 800         int rc;
 801
 802         gig_dbg(DEBUG_INIT, "%s", __func__);
 803
 804         if (driver) {
 805                 gigaset_freedriver(driver);
 806                 driver = NULL;
 807         }
 808
 809         rc = tty_unregister_ldisc(N_GIGASET_M101);
 810         if (rc != 0)
 811                 pr_err("error %d unregistering line discipline\n", rc);
 812
 813         platform_driver_unregister(&device_driver);
 814 }
 815
 816 module_init(ser_gigaset_init);
 817 module_exit(ser_gigaset_exit);