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/tty.h>
  32 #include <linux/init.h>
  33 #include <asm/uaccess.h>
  34 #include <linux/smp_lock.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, NULL, 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         tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
 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", __FUNCTION__);
 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         tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
 267
 268         if (priv->dev)
 269                 sirdev_write_complete(priv->dev);
 270 }
 271
 272 /* ------------------------------------------------------- */
 273
 274 /*
 275  * Function irtty_stop_receiver (tty, stop)
 276  *
 277  */
 278
 279 static inline void irtty_stop_receiver(struct tty_struct *tty, int stop)
 280 {
 281         struct ktermios old_termios;
 282         int cflag;
 283
 284         mutex_lock(&tty->termios_mutex);
 285         old_termios = *(tty->termios);
 286         cflag = tty->termios->c_cflag;
 287
 288         if (stop)
 289                 cflag &= ~CREAD;
 290         else
 291                 cflag |= CREAD;
 292
 293         tty->termios->c_cflag = cflag;
 294         if (tty->ops->set_termios)
 295                 tty->ops->set_termios(tty, &old_termios);
 296         mutex_unlock(&tty->termios_mutex);
 297 }
 298
 299 /*****************************************************************/
 300
 301 /* serialize ldisc open/close with sir_dev */
 302 static DEFINE_MUTEX(irtty_mutex);
 303
 304 /* notifier from sir_dev when irda% device gets opened (ifup) */
 305
 306 static int irtty_start_dev(struct sir_dev *dev)
 307 {
 308         struct sirtty_cb *priv;
 309         struct tty_struct *tty;
 310
 311         /* serialize with ldisc open/close */
 312         mutex_lock(&irtty_mutex);
 313
 314         priv = dev->priv;
 315         if (unlikely(!priv || priv->magic!=IRTTY_MAGIC)) {
 316                 mutex_unlock(&irtty_mutex);
 317                 return -ESTALE;
 318         }
 319
 320         tty = priv->tty;
 321
 322         if (tty->ops->start)
 323                 tty->ops->start(tty);
 324         /* Make sure we can receive more data */
 325         irtty_stop_receiver(tty, FALSE);
 326
 327         mutex_unlock(&irtty_mutex);
 328         return 0;
 329 }
 330
 331 /* notifier from sir_dev when irda% device gets closed (ifdown) */
 332
 333 static int irtty_stop_dev(struct sir_dev *dev)
 334 {
 335         struct sirtty_cb *priv;
 336         struct tty_struct *tty;
 337
 338         /* serialize with ldisc open/close */
 339         mutex_lock(&irtty_mutex);
 340
 341         priv = dev->priv;
 342         if (unlikely(!priv || priv->magic!=IRTTY_MAGIC)) {
 343                 mutex_unlock(&irtty_mutex);
 344                 return -ESTALE;
 345         }
 346
 347         tty = priv->tty;
 348
 349         /* Make sure we don't receive more data */
 350         irtty_stop_receiver(tty, TRUE);
 351         if (tty->ops->stop)
 352                 tty->ops->stop(tty);
 353
 354         mutex_unlock(&irtty_mutex);
 355
 356         return 0;
 357 }
 358
 359 /* ------------------------------------------------------- */
 360
 361 static struct sir_driver sir_tty_drv = {
 362         .owner                  = THIS_MODULE,
 363         .driver_name            = "sir_tty",
 364         .start_dev              = irtty_start_dev,
 365         .stop_dev               = irtty_stop_dev,
 366         .do_write               = irtty_do_write,
 367         .chars_in_buffer        = irtty_chars_in_buffer,
 368         .wait_until_sent        = irtty_wait_until_sent,
 369         .set_speed              = irtty_change_speed,
 370         .set_dtr_rts            = irtty_set_dtr_rts,
 371 };
 372
 373 /* ------------------------------------------------------- */
 374
 375 /*
 376  * Function irtty_ioctl (tty, file, cmd, arg)
 377  *
 378  *     The Swiss army knife of system calls :-)
 379  *
 380  */
 381 static int irtty_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
 382 {
 383         struct irtty_info { char name[6]; } info;
 384         struct sir_dev *dev;
 385         struct sirtty_cb *priv = tty->disc_data;
 386         int err = 0;
 387
 388         IRDA_ASSERT(priv != NULL, return -ENODEV;);
 389         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -EBADR;);
 390
 391         IRDA_DEBUG(3, "%s(cmd=0x%X)\n", __FUNCTION__, cmd);
 392
 393         dev = priv->dev;
 394         IRDA_ASSERT(dev != NULL, return -1;);
 395
 396         switch (cmd) {
 397         case IRTTY_IOCTDONGLE:
 398                 /* this call blocks for completion */
 399                 err = sirdev_set_dongle(dev, (IRDA_DONGLE) arg);
 400                 break;
 401
 402         case IRTTY_IOCGET:
 403                 IRDA_ASSERT(dev->netdev != NULL, return -1;);
 404
 405                 memset(&info, 0, sizeof(info));
 406                 strncpy(info.name, dev->netdev->name, sizeof(info.name)-1);
 407
 408                 if (copy_to_user((void __user *)arg, &info, sizeof(info)))
 409                         err = -EFAULT;
 410                 break;
 411         default:
 412                 err = tty_mode_ioctl(tty, file, cmd, arg);
 413                 break;
 414         }
 415         return err;
 416 }
 417
 418
 419 /*
 420  *  Function irtty_open(tty)
 421  *
 422  *    This function is called by the TTY module when the IrDA line
 423  *    discipline is called for.  Because we are sure the tty line exists,
 424  *    we only have to link it to a free IrDA channel.
 425  */
 426 static int irtty_open(struct tty_struct *tty)
 427 {
 428         struct sir_dev *dev;
 429         struct sirtty_cb *priv;
 430         int ret = 0;
 431
 432         /* Module stuff handled via irda_ldisc.owner - Jean II */
 433
 434         /* First make sure we're not already connected. */
 435         if (tty->disc_data != NULL) {
 436                 priv = tty->disc_data;
 437                 if (priv && priv->magic == IRTTY_MAGIC) {
 438                         ret = -EEXIST;
 439                         goto out;
 440                 }
 441                 tty->disc_data = NULL;          /* ### */
 442         }
 443
 444         /* stop the underlying  driver */
 445         irtty_stop_receiver(tty, TRUE);
 446         if (tty->ops->stop)
 447                 tty->ops->stop(tty);
 448
 449         tty_driver_flush_buffer(tty);
 450
 451         /* apply mtt override */
 452         sir_tty_drv.qos_mtt_bits = qos_mtt_bits;
 453
 454         /* get a sir device instance for this driver */
 455         dev = sirdev_get_instance(&sir_tty_drv, tty->name);
 456         if (!dev) {
 457                 ret = -ENODEV;
 458                 goto out;
 459         }
 460
 461         /* allocate private device info block */
 462         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 463         if (!priv)
 464                 goto out_put;
 465
 466         priv->magic = IRTTY_MAGIC;
 467         priv->tty = tty;
 468         priv->dev = dev;
 469
 470         /* serialize with start_dev - in case we were racing with ifup */
 471         mutex_lock(&irtty_mutex);
 472
 473         dev->priv = priv;
 474         tty->disc_data = priv;
 475         tty->receive_room = 65536;
 476
 477         mutex_unlock(&irtty_mutex);
 478
 479         IRDA_DEBUG(0, "%s - %s: irda line discipline opened\n", __FUNCTION__, tty->name);
 480
 481         return 0;
 482
 483 out_put:
 484         sirdev_put_instance(dev);
 485 out:
 486         return ret;
 487 }
 488
 489 /*
 490  *  Function irtty_close (tty)
 491  *
 492  *    Close down a IrDA channel. This means flushing out any pending queues,
 493  *    and then restoring the TTY line discipline to what it was before it got
 494  *    hooked to IrDA (which usually is TTY again).
 495  */
 496 static void irtty_close(struct tty_struct *tty)
 497 {
 498         struct sirtty_cb *priv = tty->disc_data;
 499
 500         IRDA_ASSERT(priv != NULL, return;);
 501         IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
 502
 503         /* Hm, with a dongle attached the dongle driver wants
 504          * to close the dongle - which requires the use of
 505          * some tty write and/or termios or ioctl operations.
 506          * Are we allowed to call those when already requested
 507          * to shutdown the ldisc?
 508          * If not, we should somehow mark the dev being staled.
 509          * Question remains, how to close the dongle in this case...
 510          * For now let's assume we are granted to issue tty driver calls
 511          * until we return here from the ldisc close. I'm just wondering
 512          * how this behaves with hotpluggable serial hardware like
 513          * rs232-pcmcia card or usb-serial...
 514          *
 515          * priv->tty = NULL?;
 516          */
 517
 518         /* we are dead now */
 519         tty->disc_data = NULL;
 520
 521         sirdev_put_instance(priv->dev);
 522
 523         /* Stop tty */
 524         irtty_stop_receiver(tty, TRUE);
 525         tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
 526         if (tty->ops->stop)
 527                 tty->ops->stop(tty);
 528
 529         kfree(priv);
 530
 531         IRDA_DEBUG(0, "%s - %s: irda line discipline closed\n", __FUNCTION__, tty->name);
 532 }
 533
 534 /* ------------------------------------------------------- */
 535
 536 static struct tty_ldisc irda_ldisc = {
 537         .magic          = TTY_LDISC_MAGIC,
 538         .name           = "irda",
 539         .flags          = 0,
 540         .open           = irtty_open,
 541         .close          = irtty_close,
 542         .read           = NULL,
 543         .write          = NULL,
 544         .ioctl          = irtty_ioctl,
 545         .poll           = NULL,
 546         .receive_buf    = irtty_receive_buf,
 547         .write_wakeup   = irtty_write_wakeup,
 548         .owner          = THIS_MODULE,
 549 };
 550
 551 /* ------------------------------------------------------- */
 552
 553 static int __init irtty_sir_init(void)
 554 {
 555         int err;
 556
 557         if ((err = tty_register_ldisc(N_IRDA, &irda_ldisc)) != 0)
 558                 IRDA_ERROR("IrDA: can't register line discipline (err = %d)\n",
 559                            err);
 560         return err;
 561 }
 562
 563 static void __exit irtty_sir_cleanup(void)
 564 {
 565         int err;
 566
 567         if ((err = tty_unregister_ldisc(N_IRDA))) {
 568                 IRDA_ERROR("%s(), can't unregister line discipline (err = %d)\n",
 569                            __FUNCTION__, err);
 570         }
 571 }
 572
 573 module_init(irtty_sir_init);
 574 module_exit(irtty_sir_cleanup);
 575
 576 MODULE_AUTHOR("Dag Brattli <dagb@cs.uit.no>");
 577 MODULE_DESCRIPTION("IrDA TTY device driver");
 578 MODULE_ALIAS_LDISC(N_IRDA);
 579 MODULE_LICENSE("GPL");
 580