drivers/net/irda/irtty-sir.c

   1 /*********************************************************************
   2  *
   3  * Filename:      irtty-sir.c
   4  * Version:       2.0
   5  * Description:   IrDA line discipline implementation
   6  * Status:        Experimental.
   7  * Author:        Dag Brattli <dagb@cs.uit.no>
   8  * Created at:    Tue Dec  9 21:18:38 1997
   9  * Modified at:   Sun Oct 27 22:13:30 2002
  10  * Modified by:   Martin Diehl <mad@mdiehl.de>
  11  * Sources:       slip.c by Laurence Culhane,   <loz@holmes.demon.co.uk>
  12  *                          Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  13  *
  14  *     Copyright (c) 1998-2000 Dag Brattli,
  15  *     Copyright (c) 2002 Martin Diehl,
  16  *     All Rights Reserved.
  17  *
  18  *     This program is free software; you can redistribute it and/or
  19  *     modify it under the terms of the GNU General Public License as
  20  *     published by the Free Software Foundation; either version 2 of
  21  *     the License, or (at your option) any later version.
  22  *
  23  *     Neither Dag Brattli nor University of Tromsø admit liability nor
  24  *     provide warranty for any of this software. This material is
  25  *     provided "AS-IS" and at no charge.
  26  *
  27  ********************************************************************/
  28
  29 #include <linux/module.h>
  30 #include <linux/kernel.h>
  31 #include <linux/slab.h>
  32 #include <linux/tty.h>
  33 #include <linux/init.h>
  34 #include <asm/uaccess.h>
  35 #include <linux/delay.h>
  36 #include <linux/mutex.h>
  37
  38 #include <net/irda/irda.h>
  39 #include <net/irda/irda_device.h>
  40
  41 #include "sir-dev.h"
  42 #include "irtty-sir.h"
  43
  44 static int qos_mtt_bits = 0x03;      /* 5 ms or more */
  45
  46 module_param(qos_mtt_bits, int, 0);
  47 MODULE_PARM_DESC(qos_mtt_bits, "Minimum Turn Time");
  48
  49 /* ------------------------------------------------------- */
  50
  51 /* device configuration callbacks always invoked with irda-thread context */
  52
  53 /* find out, how many chars we have in buffers below us
  54  * this is allowed to lie, i.e. return less chars than we
  55  * actually have. The returned value is used to determine
  56  * how long the irdathread should wait before doing the
  57  * real blocking wait_until_sent()
  58  */
  59
  60 static int irtty_chars_in_buffer(struct sir_dev *dev)
  61 {
  62         struct sirtty_cb *priv = dev->priv;
  63
  64         IRDA_ASSERT(priv != NULL, return -1;);
  65         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
  66
  67         return tty_chars_in_buffer(priv->tty);
  68 }
  69
  70 /* Wait (sleep) until underlaying hardware finished transmission
  71  * i.e. hardware buffers are drained
  72  * this must block and not return before all characters are really sent
  73  *
  74  * If the tty sits on top of a 16550A-like uart, there are typically
  75  * up to 16 bytes in the fifo - f.e. 9600 bps 8N1 needs 16.7 msec
  76  *
  77  * With usbserial the uart-fifo is basically replaced by the converter's
  78  * outgoing endpoint buffer, which can usually hold 64 bytes (at least).
  79  * With pl2303 it appears we are safe with 60msec here.
  80  *
  81  * I really wish all serial drivers would provide
  82  * correct implementation of wait_until_sent()
  83  */
  84
  85 #define USBSERIAL_TX_DONE_DELAY 60
  86
  87 static void irtty_wait_until_sent(struct sir_dev *dev)
  88 {
  89         struct sirtty_cb *priv = dev->priv;
  90         struct tty_struct *tty;
  91
  92         IRDA_ASSERT(priv != NULL, return;);
  93         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
  94
  95         tty = priv->tty;
  96         if (tty->ops->wait_until_sent) {
  97                 tty->ops->wait_until_sent(tty, msecs_to_jiffies(100));
  98         }
  99         else {
 100                 msleep(USBSERIAL_TX_DONE_DELAY);
 101         }
 102 }
 103
 104 /*
 105  *  Function irtty_change_speed (dev, speed)
 106  *
 107  *    Change the speed of the serial port.
 108  *
 109  * This may sleep in set_termios (usbserial driver f.e.) and must
 110  * not be called from interrupt/timer/tasklet therefore.
 111  * All such invocations are deferred to kIrDAd now so we can sleep there.
 112  */
 113
 114 static int irtty_change_speed(struct sir_dev *dev, unsigned speed)
 115 {
 116         struct sirtty_cb *priv = dev->priv;
 117         struct tty_struct *tty;
 118         struct ktermios old_termios;
 119         int cflag;
 120
 121         IRDA_ASSERT(priv != NULL, return -1;);
 122         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
 123
 124         tty = priv->tty;
 125
 126         mutex_lock(&tty->termios_mutex);
 127         old_termios = *(tty->termios);
 128         cflag = tty->termios->c_cflag;
 129         tty_encode_baud_rate(tty, speed, speed);
 130         if (tty->ops->set_termios)
 131                 tty->ops->set_termios(tty, &old_termios);
 132         priv->io.speed = speed;
 133         mutex_unlock(&tty->termios_mutex);
 134
 135         return 0;
 136 }
 137
 138 /*
 139  * Function irtty_set_dtr_rts (dev, dtr, rts)
 140  *
 141  *    This function can be used by dongles etc. to set or reset the status
 142  *    of the dtr and rts lines
 143  */
 144
 145 static int irtty_set_dtr_rts(struct sir_dev *dev, int dtr, int rts)
 146 {
 147         struct sirtty_cb *priv = dev->priv;
 148         int set = 0;
 149         int clear = 0;
 150
 151         IRDA_ASSERT(priv != NULL, return -1;);
 152         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
 153
 154         if (rts)
 155                 set |= TIOCM_RTS;
 156         else
 157                 clear |= TIOCM_RTS;
 158         if (dtr)
 159                 set |= TIOCM_DTR;
 160         else
 161                 clear |= TIOCM_DTR;
 162
 163         /*
 164          * We can't use ioctl() because it expects a non-null file structure,
 165          * and we don't have that here.
 166          * This function is not yet defined for all tty driver, so
 167          * let's be careful... Jean II
 168          */
 169         IRDA_ASSERT(priv->tty->ops->tiocmset != NULL, return -1;);
 170         priv->tty->ops->tiocmset(priv->tty, set, clear);
 171
 172         return 0;
 173 }
 174
 175 /* ------------------------------------------------------- */
 176
 177 /* called from sir_dev when there is more data to send
 178  * context is either netdev->hard_xmit or some transmit-completion bh
 179  * i.e. we are under spinlock here and must not sleep.
 180  */
 181
 182 static int irtty_do_write(struct sir_dev *dev, const unsigned char *ptr, size_t len)
 183 {
 184         struct sirtty_cb *priv = dev->priv;
 185         struct tty_struct *tty;
 186         int writelen;
 187
 188         IRDA_ASSERT(priv != NULL, return -1;);
 189         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
 190
 191         tty = priv->tty;
 192         if (!tty->ops->write)
 193                 return 0;
 194         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 195         writelen = tty_write_room(tty);
 196         if (writelen > len)
 197                 writelen = len;
 198         return tty->ops->write(tty, ptr, writelen);
 199 }
 200
 201 /* ------------------------------------------------------- */
 202
 203 /* irda line discipline callbacks */
 204
 205 /*
 206  *  Function irtty_receive_buf( tty, cp, count)
 207  *
 208  *    Handle the 'receiver data ready' interrupt.  This function is called
 209  *    by the 'tty_io' module in the kernel when a block of IrDA data has
 210  *    been received, which can now be decapsulated and delivered for
 211  *    further processing
 212  *
 213  * calling context depends on underlying driver and tty->low_latency!
 214  * for example (low_latency: 1 / 0):
 215  * serial.c:    uart-interrupt / softint
 216  * usbserial:   urb-complete-interrupt / softint
 217  */
 218
 219 static void irtty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 220                               char *fp, int count)
 221 {
 222         struct sir_dev *dev;
 223         struct sirtty_cb *priv = tty->disc_data;
 224         int     i;
 225
 226         IRDA_ASSERT(priv != NULL, return;);
 227         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
 228
 229         if (unlikely(count==0))         /* yes, this happens */
 230                 return;
 231
 232         dev = priv->dev;
 233         if (!dev) {
 234                 IRDA_WARNING("%s(), not ready yet!\n", __func__);
 235                 return;
 236         }
 237
 238         for (i = 0; i < count; i++) {
 239                 /*
 240                  *  Characters received with a parity error, etc?
 241                  */
 242                 if (fp && *fp++) {
 243                         IRDA_DEBUG(0, "Framing or parity error!\n");
 244                         sirdev_receive(dev, NULL, 0);   /* notify sir_dev (updating stats) */
 245                         return;
 246                 }
 247         }
 248
 249         sirdev_receive(dev, cp, count);
 250 }
 251
 252 /*
 253  * Function irtty_write_wakeup (tty)
 254  *
 255  *    Called by the driver when there's room for more data.  If we have
 256  *    more packets to send, we send them here.
 257  *
 258  */
 259 static void irtty_write_wakeup(struct tty_struct *tty)
 260 {
 261         struct sirtty_cb *priv = tty->disc_data;
 262
 263         IRDA_ASSERT(priv != NULL, return;);
 264         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
 265
 266         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 267         if (priv->dev)
 268                 sirdev_write_complete(priv->dev);
 269 }
 270
 271 /* ------------------------------------------------------- */
 272
 273 /*
 274  * Function irtty_stop_receiver (tty, stop)
 275  *
 276  */
 277
 278 static inline void irtty_stop_receiver(struct tty_struct *tty, int stop)
 279 {
 280         struct ktermios old_termios;
 281         int cflag;
 282
 283         mutex_lock(&tty->termios_mutex);
 284         old_termios = *(tty->termios);
 285         cflag = tty->termios->c_cflag;
 286
 287         if (stop)
 288                 cflag &= ~CREAD;
 289         else
 290                 cflag |= CREAD;
 291
 292         tty->termios->c_cflag = cflag;
 293         if (tty->ops->set_termios)
 294                 tty->ops->set_termios(tty, &old_termios);
 295         mutex_unlock(&tty->termios_mutex);
 296 }
 297
 298 /*****************************************************************/
 299
 300 /* serialize ldisc open/close with sir_dev */
 301 static DEFINE_MUTEX(irtty_mutex);
 302
 303 /* notifier from sir_dev when irda% device gets opened (ifup) */
 304
 305 static int irtty_start_dev(struct sir_dev *dev)
 306 {
 307         struct sirtty_cb *priv;
 308         struct tty_struct *tty;
 309
 310         /* serialize with ldisc open/close */
 311         mutex_lock(&irtty_mutex);
 312
 313         priv = dev->priv;
 314         if (unlikely(!priv || priv->magic!=IRTTY_MAGIC)) {
 315                 mutex_unlock(&irtty_mutex);
 316                 return -ESTALE;
 317         }
 318
 319         tty = priv->tty;
 320
 321         if (tty->ops->start)
 322                 tty->ops->start(tty);
 323         /* Make sure we can receive more data */
 324         irtty_stop_receiver(tty, FALSE);
 325
 326         mutex_unlock(&irtty_mutex);
 327         return 0;
 328 }
 329
 330 /* notifier from sir_dev when irda% device gets closed (ifdown) */
 331
 332 static int irtty_stop_dev(struct sir_dev *dev)
 333 {
 334         struct sirtty_cb *priv;
 335         struct tty_struct *tty;
 336
 337         /* serialize with ldisc open/close */
 338         mutex_lock(&irtty_mutex);
 339
 340         priv = dev->priv;
 341         if (unlikely(!priv || priv->magic!=IRTTY_MAGIC)) {
 342                 mutex_unlock(&irtty_mutex);
 343                 return -ESTALE;
 344         }
 345
 346         tty = priv->tty;
 347
 348         /* Make sure we don't receive more data */
 349         irtty_stop_receiver(tty, TRUE);
 350         if (tty->ops->stop)
 351                 tty->ops->stop(tty);
 352
 353         mutex_unlock(&irtty_mutex);
 354
 355         return 0;
 356 }
 357
 358 /* ------------------------------------------------------- */
 359
 360 static struct sir_driver sir_tty_drv = {
 361         .owner                  = THIS_MODULE,
 362         .driver_name            = "sir_tty",
 363         .start_dev              = irtty_start_dev,
 364         .stop_dev               = irtty_stop_dev,
 365         .do_write               = irtty_do_write,
 366         .chars_in_buffer        = irtty_chars_in_buffer,
 367         .wait_until_sent        = irtty_wait_until_sent,
 368         .set_speed              = irtty_change_speed,
 369         .set_dtr_rts            = irtty_set_dtr_rts,
 370 };
 371
 372 /* ------------------------------------------------------- */
 373
 374 /*
 375  * Function irtty_ioctl (tty, file, cmd, arg)
 376  *
 377  *     The Swiss army knife of system calls :-)
 378  *
 379  */
 380 static int irtty_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
 381 {
 382         struct irtty_info { char name[6]; } info;
 383         struct sir_dev *dev;
 384         struct sirtty_cb *priv = tty->disc_data;
 385         int err = 0;
 386
 387         IRDA_ASSERT(priv != NULL, return -ENODEV;);
 388         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -EBADR;);
 389
 390         IRDA_DEBUG(3, "%s(cmd=0x%X)\n", __func__, cmd);
 391
 392         dev = priv->dev;
 393         IRDA_ASSERT(dev != NULL, return -1;);
 394
 395         switch (cmd) {
 396         case IRTTY_IOCTDONGLE:
 397                 /* this call blocks for completion */
 398                 err = sirdev_set_dongle(dev, (IRDA_DONGLE) arg);
 399                 break;
 400
 401         case IRTTY_IOCGET:
 402                 IRDA_ASSERT(dev->netdev != NULL, return -1;);
 403
 404                 memset(&info, 0, sizeof(info));
 405                 strncpy(info.name, dev->netdev->name, sizeof(info.name)-1);
 406
 407                 if (copy_to_user((void __user *)arg, &info, sizeof(info)))
 408                         err = -EFAULT;
 409                 break;
 410         default:
 411                 err = tty_mode_ioctl(tty, file, cmd, arg);
 412                 break;
 413         }
 414         return err;
 415 }
 416
 417
 418 /*
 419  *  Function irtty_open(tty)
 420  *
 421  *    This function is called by the TTY module when the IrDA line
 422  *    discipline is called for.  Because we are sure the tty line exists,
 423  *    we only have to link it to a free IrDA channel.
 424  */
 425 static int irtty_open(struct tty_struct *tty)
 426 {
 427         struct sir_dev *dev;
 428         struct sirtty_cb *priv;
 429         int ret = 0;
 430
 431         /* Module stuff handled via irda_ldisc.owner - Jean II */
 432
 433         /* First make sure we're not already connected. */
 434         if (tty->disc_data != NULL) {
 435                 priv = tty->disc_data;
 436                 if (priv && priv->magic == IRTTY_MAGIC) {
 437                         ret = -EEXIST;
 438                         goto out;
 439                 }
 440                 tty->disc_data = NULL;          /* ### */
 441         }
 442
 443         /* stop the underlying  driver */
 444         irtty_stop_receiver(tty, TRUE);
 445         if (tty->ops->stop)
 446                 tty->ops->stop(tty);
 447
 448         tty_driver_flush_buffer(tty);
 449
 450         /* apply mtt override */
 451         sir_tty_drv.qos_mtt_bits = qos_mtt_bits;
 452
 453         /* get a sir device instance for this driver */
 454         dev = sirdev_get_instance(&sir_tty_drv, tty->name);
 455         if (!dev) {
 456                 ret = -ENODEV;
 457                 goto out;
 458         }
 459
 460         /* allocate private device info block */
 461         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 462         if (!priv)
 463                 goto out_put;
 464
 465         priv->magic = IRTTY_MAGIC;
 466         priv->tty = tty;
 467         priv->dev = dev;
 468
 469         /* serialize with start_dev - in case we were racing with ifup */
 470         mutex_lock(&irtty_mutex);
 471
 472         dev->priv = priv;
 473         tty->disc_data = priv;
 474         tty->receive_room = 65536;
 475
 476         mutex_unlock(&irtty_mutex);
 477
 478         IRDA_DEBUG(0, "%s - %s: irda line discipline opened\n", __func__, tty->name);
 479
 480         return 0;
 481
 482 out_put:
 483         sirdev_put_instance(dev);
 484 out:
 485         return ret;
 486 }
 487
 488 /*
 489  *  Function irtty_close (tty)
 490  *
 491  *    Close down a IrDA channel. This means flushing out any pending queues,
 492  *    and then restoring the TTY line discipline to what it was before it got
 493  *    hooked to IrDA (which usually is TTY again).
 494  */
 495 static void irtty_close(struct tty_struct *tty)
 496 {
 497         struct sirtty_cb *priv = tty->disc_data;
 498
 499         IRDA_ASSERT(priv != NULL, return;);
 500         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
 501
 502         /* Hm, with a dongle attached the dongle driver wants
 503          * to close the dongle - which requires the use of
 504          * some tty write and/or termios or ioctl operations.
 505          * Are we allowed to call those when already requested
 506          * to shutdown the ldisc?
 507          * If not, we should somehow mark the dev being staled.
 508          * Question remains, how to close the dongle in this case...
 509          * For now let's assume we are granted to issue tty driver calls
 510          * until we return here from the ldisc close. I'm just wondering
 511          * how this behaves with hotpluggable serial hardware like
 512          * rs232-pcmcia card or usb-serial...
 513          *
 514          * priv->tty = NULL?;
 515          */
 516
 517         /* we are dead now */
 518         tty->disc_data = NULL;
 519
 520         sirdev_put_instance(priv->dev);
 521
 522         /* Stop tty */
 523         irtty_stop_receiver(tty, TRUE);
 524         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 525         if (tty->ops->stop)
 526                 tty->ops->stop(tty);
 527
 528         kfree(priv);
 529
 530         IRDA_DEBUG(0, "%s - %s: irda line discipline closed\n", __func__, tty->name);
 531 }
 532
 533 /* ------------------------------------------------------- */
 534
 535 static struct tty_ldisc_ops irda_ldisc = {
 536         .magic          = TTY_LDISC_MAGIC,
 537         .name           = "irda",
 538         .flags          = 0,
 539         .open           = irtty_open,
 540         .close          = irtty_close,
 541         .read           = NULL,
 542         .write          = NULL,
 543         .ioctl          = irtty_ioctl,
 544         .poll           = NULL,
 545         .receive_buf    = irtty_receive_buf,
 546         .write_wakeup   = irtty_write_wakeup,
 547         .owner          = THIS_MODULE,
 548 };
 549
 550 /* ------------------------------------------------------- */
 551
 552 static int __init irtty_sir_init(void)
 553 {
 554         int err;
 555
 556         if ((err = tty_register_ldisc(N_IRDA, &irda_ldisc)) != 0)
 557                 IRDA_ERROR("IrDA: can't register line discipline (err = %d)\n",
 558                            err);
 559         return err;
 560 }
 561
 562 static void __exit irtty_sir_cleanup(void)
 563 {
 564         int err;
 565
 566         if ((err = tty_unregister_ldisc(N_IRDA))) {
 567                 IRDA_ERROR("%s(), can't unregister line discipline (err = %d)\n",
 568                            __func__, err);
 569         }
 570 }
 571
 572 module_init(irtty_sir_init);
 573 module_exit(irtty_sir_cleanup);
 574
 575 MODULE_AUTHOR("Dag Brattli <dagb@cs.uit.no>");
 576 MODULE_DESCRIPTION("IrDA TTY device driver");
 577 MODULE_ALIAS_LDISC(N_IRDA);
 578 MODULE_LICENSE("GPL");
 579