drivers/net/irda/sir_kthread.c

   1 /*********************************************************************
   2  *
   3  *      sir_kthread.c:          dedicated thread to process scheduled
   4  *                              sir device setup requests
   5  *
   6  *      Copyright (c) 2002 Martin Diehl
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License as
  10  *      published by the Free Software Foundation; either version 2 of
  11  *      the License, or (at your option) any later version.
  12  *
  13  ********************************************************************/
  14
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/version.h>
  18 #include <linux/init.h>
  19 #include <linux/smp_lock.h>
  20 #include <linux/completion.h>
  21 #include <linux/delay.h>
  22
  23 #include <net/irda/irda.h>
  24
  25 #include "sir-dev.h"
  26
  27 /**************************************************************************
  28  *
  29  * kIrDAd kernel thread and config state machine
  30  *
  31  */
  32
  33 struct irda_request_queue {
  34         struct list_head request_list;
  35         spinlock_t lock;
  36         task_t *thread;
  37         struct completion exit;
  38         wait_queue_head_t kick, done;
  39         atomic_t num_pending;
  40 };
  41
  42 static struct irda_request_queue irda_rq_queue;
  43
  44 static int irda_queue_request(struct irda_request *rq)
  45 {
  46         int ret = 0;
  47         unsigned long flags;
  48
  49         if (!test_and_set_bit(0, &rq->pending)) {
  50                 spin_lock_irqsave(&irda_rq_queue.lock, flags);
  51                 list_add_tail(&rq->lh_request, &irda_rq_queue.request_list);
  52                 wake_up(&irda_rq_queue.kick);
  53                 atomic_inc(&irda_rq_queue.num_pending);
  54                 spin_unlock_irqrestore(&irda_rq_queue.lock, flags);
  55                 ret = 1;
  56         }
  57         return ret;
  58 }
  59
  60 static void irda_request_timer(unsigned long data)
  61 {
  62         struct irda_request *rq = (struct irda_request *)data;
  63         unsigned long flags;
  64
  65         spin_lock_irqsave(&irda_rq_queue.lock, flags);
  66         list_add_tail(&rq->lh_request, &irda_rq_queue.request_list);
  67         wake_up(&irda_rq_queue.kick);
  68         spin_unlock_irqrestore(&irda_rq_queue.lock, flags);
  69 }
  70
  71 static int irda_queue_delayed_request(struct irda_request *rq, unsigned long delay)
  72 {
  73         int ret = 0;
  74         struct timer_list *timer = &rq->timer;
  75
  76         if (!test_and_set_bit(0, &rq->pending)) {
  77                 timer->expires = jiffies + delay;
  78                 timer->function = irda_request_timer;
  79                 timer->data = (unsigned long)rq;
  80                 atomic_inc(&irda_rq_queue.num_pending);
  81                 add_timer(timer);
  82                 ret = 1;
  83         }
  84         return ret;
  85 }
  86
  87 static void run_irda_queue(void)
  88 {
  89         unsigned long flags;
  90         struct list_head *entry, *tmp;
  91         struct irda_request *rq;
  92
  93         spin_lock_irqsave(&irda_rq_queue.lock, flags);
  94         list_for_each_safe(entry, tmp, &irda_rq_queue.request_list) {
  95                 rq = list_entry(entry, struct irda_request, lh_request);
  96                 list_del_init(entry);
  97                 spin_unlock_irqrestore(&irda_rq_queue.lock, flags);
  98
  99                 clear_bit(0, &rq->pending);
 100                 rq->func(rq->data);
 101
 102                 if (atomic_dec_and_test(&irda_rq_queue.num_pending))
 103                         wake_up(&irda_rq_queue.done);
 104
 105                 spin_lock_irqsave(&irda_rq_queue.lock, flags);
 106         }
 107         spin_unlock_irqrestore(&irda_rq_queue.lock, flags);
 108 }
 109
 110 static int irda_thread(void *startup)
 111 {
 112         DECLARE_WAITQUEUE(wait, current);
 113
 114         daemonize("kIrDAd");
 115
 116         irda_rq_queue.thread = current;
 117
 118         complete((struct completion *)startup);
 119
 120         while (irda_rq_queue.thread != NULL) {
 121
 122                 /* We use TASK_INTERRUPTIBLE, rather than
 123                  * TASK_UNINTERRUPTIBLE.  Andrew Morton made this
 124                  * change ; he told me that it is safe, because "signal
 125                  * blocking is now handled in daemonize()", he added
 126                  * that the problem is that "uninterruptible sleep
 127                  * contributes to load average", making user worry.
 128                  * Jean II */
 129                 set_task_state(current, TASK_INTERRUPTIBLE);
 130                 add_wait_queue(&irda_rq_queue.kick, &wait);
 131                 if (list_empty(&irda_rq_queue.request_list))
 132                         schedule();
 133                 else
 134                         __set_task_state(current, TASK_RUNNING);
 135                 remove_wait_queue(&irda_rq_queue.kick, &wait);
 136
 137                 /* make swsusp happy with our thread */
 138                 try_to_freeze();
 139
 140                 run_irda_queue();
 141         }
 142
 143 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,35)
 144         reparent_to_init();
 145 #endif
 146         complete_and_exit(&irda_rq_queue.exit, 0);
 147         /* never reached */
 148         return 0;
 149 }
 150
 151
 152 static void flush_irda_queue(void)
 153 {
 154         if (atomic_read(&irda_rq_queue.num_pending)) {
 155
 156                 DECLARE_WAITQUEUE(wait, current);
 157
 158                 if (!list_empty(&irda_rq_queue.request_list))
 159                         run_irda_queue();
 160
 161                 set_task_state(current, TASK_UNINTERRUPTIBLE);
 162                 add_wait_queue(&irda_rq_queue.done, &wait);
 163                 if (atomic_read(&irda_rq_queue.num_pending))
 164                         schedule();
 165                 else
 166                         __set_task_state(current, TASK_RUNNING);
 167                 remove_wait_queue(&irda_rq_queue.done, &wait);
 168         }
 169 }
 170
 171 /* substate handler of the config-fsm to handle the cases where we want
 172  * to wait for transmit completion before changing the port configuration
 173  */
 174
 175 static int irda_tx_complete_fsm(struct sir_dev *dev)
 176 {
 177         struct sir_fsm *fsm = &dev->fsm;
 178         unsigned next_state, delay;
 179         unsigned bytes_left;
 180
 181         do {
 182                 next_state = fsm->substate;     /* default: stay in current substate */
 183                 delay = 0;
 184
 185                 switch(fsm->substate) {
 186
 187                 case SIRDEV_STATE_WAIT_XMIT:
 188                         if (dev->drv->chars_in_buffer)
 189                                 bytes_left = dev->drv->chars_in_buffer(dev);
 190                         else
 191                                 bytes_left = 0;
 192                         if (!bytes_left) {
 193                                 next_state = SIRDEV_STATE_WAIT_UNTIL_SENT;
 194                                 break;
 195                         }
 196
 197                         if (dev->speed > 115200)
 198                                 delay = (bytes_left*8*10000) / (dev->speed/100);
 199                         else if (dev->speed > 0)
 200                                 delay = (bytes_left*10*10000) / (dev->speed/100);
 201                         else
 202                                 delay = 0;
 203                         /* expected delay (usec) until remaining bytes are sent */
 204                         if (delay < 100) {
 205                                 udelay(delay);
 206                                 delay = 0;
 207                                 break;
 208                         }
 209                         /* sleep some longer delay (msec) */
 210                         delay = (delay+999) / 1000;
 211                         break;
 212
 213                 case SIRDEV_STATE_WAIT_UNTIL_SENT:
 214                         /* block until underlaying hardware buffer are empty */
 215                         if (dev->drv->wait_until_sent)
 216                                 dev->drv->wait_until_sent(dev);
 217                         next_state = SIRDEV_STATE_TX_DONE;
 218                         break;
 219
 220                 case SIRDEV_STATE_TX_DONE:
 221                         return 0;
 222
 223                 default:
 224                         IRDA_ERROR("%s - undefined state\n", __FUNCTION__);
 225                         return -EINVAL;
 226                 }
 227                 fsm->substate = next_state;
 228         } while (delay == 0);
 229         return delay;
 230 }
 231
 232 /*
 233  * Function irda_config_fsm
 234  *
 235  * State machine to handle the configuration of the device (and attached dongle, if any).
 236  * This handler is scheduled for execution in kIrDAd context, so we can sleep.
 237  * however, kIrDAd is shared by all sir_dev devices so we better don't sleep there too
 238  * long. Instead, for longer delays we start a timer to reschedule us later.
 239  * On entry, fsm->sem is always locked and the netdev xmit queue stopped.
 240  * Both must be unlocked/restarted on completion - but only on final exit.
 241  */
 242
 243 static void irda_config_fsm(void *data)
 244 {
 245         struct sir_dev *dev = data;
 246         struct sir_fsm *fsm = &dev->fsm;
 247         int next_state;
 248         int ret = -1;
 249         unsigned delay;
 250
 251         IRDA_DEBUG(2, "%s(), <%ld>\n", __FUNCTION__, jiffies);
 252
 253         do {
 254                 IRDA_DEBUG(3, "%s - state=0x%04x / substate=0x%04x\n",
 255                         __FUNCTION__, fsm->state, fsm->substate);
 256
 257                 next_state = fsm->state;
 258                 delay = 0;
 259
 260                 switch(fsm->state) {
 261
 262                 case SIRDEV_STATE_DONGLE_OPEN:
 263                         if (dev->dongle_drv != NULL) {
 264                                 ret = sirdev_put_dongle(dev);
 265                                 if (ret) {
 266                                         fsm->result = -EINVAL;
 267                                         next_state = SIRDEV_STATE_ERROR;
 268                                         break;
 269                                 }
 270                         }
 271
 272                         /* Initialize dongle */
 273                         ret = sirdev_get_dongle(dev, fsm->param);
 274                         if (ret) {
 275                                 fsm->result = ret;
 276                                 next_state = SIRDEV_STATE_ERROR;
 277                                 break;
 278                         }
 279
 280                         /* Dongles are powered through the modem control lines which
 281                          * were just set during open. Before resetting, let's wait for
 282                          * the power to stabilize. This is what some dongle drivers did
 283                          * in open before, while others didn't - should be safe anyway.
 284                          */
 285
 286                         delay = 50;
 287                         fsm->substate = SIRDEV_STATE_DONGLE_RESET;
 288                         next_state = SIRDEV_STATE_DONGLE_RESET;
 289
 290                         fsm->param = 9600;
 291
 292                         break;
 293
 294                 case SIRDEV_STATE_DONGLE_CLOSE:
 295                         /* shouldn't we just treat this as success=? */
 296                         if (dev->dongle_drv == NULL) {
 297                                 fsm->result = -EINVAL;
 298                                 next_state = SIRDEV_STATE_ERROR;
 299                                 break;
 300                         }
 301
 302                         ret = sirdev_put_dongle(dev);
 303                         if (ret) {
 304                                 fsm->result = ret;
 305                                 next_state = SIRDEV_STATE_ERROR;
 306                                 break;
 307                         }
 308                         next_state = SIRDEV_STATE_DONE;
 309                         break;
 310
 311                 case SIRDEV_STATE_SET_DTR_RTS:
 312                         ret = sirdev_set_dtr_rts(dev,
 313                                 (fsm->param&0x02) ? TRUE : FALSE,
 314                                 (fsm->param&0x01) ? TRUE : FALSE);
 315                         next_state = SIRDEV_STATE_DONE;
 316                         break;
 317
 318                 case SIRDEV_STATE_SET_SPEED:
 319                         fsm->substate = SIRDEV_STATE_WAIT_XMIT;
 320                         next_state = SIRDEV_STATE_DONGLE_CHECK;
 321                         break;
 322
 323                 case SIRDEV_STATE_DONGLE_CHECK:
 324                         ret = irda_tx_complete_fsm(dev);
 325                         if (ret < 0) {
 326                                 fsm->result = ret;
 327                                 next_state = SIRDEV_STATE_ERROR;
 328                                 break;
 329                         }
 330                         if ((delay=ret) != 0)
 331                                 break;
 332
 333                         if (dev->dongle_drv) {
 334                                 fsm->substate = SIRDEV_STATE_DONGLE_RESET;
 335                                 next_state = SIRDEV_STATE_DONGLE_RESET;
 336                         }
 337                         else {
 338                                 dev->speed = fsm->param;
 339                                 next_state = SIRDEV_STATE_PORT_SPEED;
 340                         }
 341                         break;
 342
 343                 case SIRDEV_STATE_DONGLE_RESET:
 344                         if (dev->dongle_drv->reset) {
 345                                 ret = dev->dongle_drv->reset(dev);
 346                                 if (ret < 0) {
 347                                         fsm->result = ret;
 348                                         next_state = SIRDEV_STATE_ERROR;
 349                                         break;
 350                                 }
 351                         }
 352                         else
 353                                 ret = 0;
 354                         if ((delay=ret) == 0) {
 355                                 /* set serial port according to dongle default speed */
 356                                 if (dev->drv->set_speed)
 357                                         dev->drv->set_speed(dev, dev->speed);
 358                                 fsm->substate = SIRDEV_STATE_DONGLE_SPEED;
 359                                 next_state = SIRDEV_STATE_DONGLE_SPEED;
 360                         }
 361                         break;
 362
 363                 case SIRDEV_STATE_DONGLE_SPEED:
 364                         if (dev->dongle_drv->reset) {
 365                                 ret = dev->dongle_drv->set_speed(dev, fsm->param);
 366                                 if (ret < 0) {
 367                                         fsm->result = ret;
 368                                         next_state = SIRDEV_STATE_ERROR;
 369                                         break;
 370                                 }
 371                         }
 372                         else
 373                                 ret = 0;
 374                         if ((delay=ret) == 0)
 375                                 next_state = SIRDEV_STATE_PORT_SPEED;
 376                         break;
 377
 378                 case SIRDEV_STATE_PORT_SPEED:
 379                         /* Finally we are ready to change the serial port speed */
 380                         if (dev->drv->set_speed)
 381                                 dev->drv->set_speed(dev, dev->speed);
 382                         dev->new_speed = 0;
 383                         next_state = SIRDEV_STATE_DONE;
 384                         break;
 385
 386                 case SIRDEV_STATE_DONE:
 387                         /* Signal network layer so it can send more frames */
 388                         netif_wake_queue(dev->netdev);
 389                         next_state = SIRDEV_STATE_COMPLETE;
 390                         break;
 391
 392                 default:
 393                         IRDA_ERROR("%s - undefined state\n", __FUNCTION__);
 394                         fsm->result = -EINVAL;
 395                         /* fall thru */
 396
 397                 case SIRDEV_STATE_ERROR:
 398                         IRDA_ERROR("%s - error: %d\n", __FUNCTION__, fsm->result);
 399
 400 #if 0   /* don't enable this before we have netdev->tx_timeout to recover */
 401                         netif_stop_queue(dev->netdev);
 402 #else
 403                         netif_wake_queue(dev->netdev);
 404 #endif
 405                         /* fall thru */
 406
 407                 case SIRDEV_STATE_COMPLETE:
 408                         /* config change finished, so we are not busy any longer */
 409                         sirdev_enable_rx(dev);
 410                         up(&fsm->sem);
 411                         return;
 412                 }
 413                 fsm->state = next_state;
 414         } while(!delay);
 415
 416         irda_queue_delayed_request(&fsm->rq, msecs_to_jiffies(delay));
 417 }
 418
 419 /* schedule some device configuration task for execution by kIrDAd
 420  * on behalf of the above state machine.
 421  * can be called from process or interrupt/tasklet context.
 422  */
 423
 424 int sirdev_schedule_request(struct sir_dev *dev, int initial_state, unsigned param)
 425 {
 426         struct sir_fsm *fsm = &dev->fsm;
 427         int xmit_was_down;
 428
 429         IRDA_DEBUG(2, "%s - state=0x%04x / param=%u\n", __FUNCTION__, initial_state, param);
 430
 431         if (down_trylock(&fsm->sem)) {
 432                 if (in_interrupt()  ||  in_atomic()  ||  irqs_disabled()) {
 433                         IRDA_DEBUG(1, "%s(), state machine busy!\n", __FUNCTION__);
 434                         return -EWOULDBLOCK;
 435                 } else
 436                         down(&fsm->sem);
 437         }
 438
 439         if (fsm->state == SIRDEV_STATE_DEAD) {
 440                 /* race with sirdev_close should never happen */
 441                 IRDA_ERROR("%s(), instance staled!\n", __FUNCTION__);
 442                 up(&fsm->sem);
 443                 return -ESTALE;         /* or better EPIPE? */
 444         }
 445
 446         xmit_was_down = netif_queue_stopped(dev->netdev);
 447         netif_stop_queue(dev->netdev);
 448         atomic_set(&dev->enable_rx, 0);
 449
 450         fsm->state = initial_state;
 451         fsm->param = param;
 452         fsm->result = 0;
 453
 454         INIT_LIST_HEAD(&fsm->rq.lh_request);
 455         fsm->rq.pending = 0;
 456         fsm->rq.func = irda_config_fsm;
 457         fsm->rq.data = dev;
 458
 459         if (!irda_queue_request(&fsm->rq)) {    /* returns 0 on error! */
 460                 atomic_set(&dev->enable_rx, 1);
 461                 if (!xmit_was_down)
 462                         netif_wake_queue(dev->netdev);
 463                 up(&fsm->sem);
 464                 return -EAGAIN;
 465         }
 466         return 0;
 467 }
 468
 469 static int __init irda_thread_create(void)
 470 {
 471         struct completion startup;
 472         int pid;
 473
 474         spin_lock_init(&irda_rq_queue.lock);
 475         irda_rq_queue.thread = NULL;
 476         INIT_LIST_HEAD(&irda_rq_queue.request_list);
 477         init_waitqueue_head(&irda_rq_queue.kick);
 478         init_waitqueue_head(&irda_rq_queue.done);
 479         atomic_set(&irda_rq_queue.num_pending, 0);
 480
 481         init_completion(&startup);
 482         pid = kernel_thread(irda_thread, &startup, CLONE_FS|CLONE_FILES);
 483         if (pid <= 0)
 484                 return -EAGAIN;
 485         else
 486                 wait_for_completion(&startup);
 487
 488         return 0;
 489 }
 490
 491 static void __exit irda_thread_join(void)
 492 {
 493         if (irda_rq_queue.thread) {
 494                 flush_irda_queue();
 495                 init_completion(&irda_rq_queue.exit);
 496                 irda_rq_queue.thread = NULL;
 497                 wake_up(&irda_rq_queue.kick);
 498                 wait_for_completion(&irda_rq_queue.exit);
 499         }
 500 }
 501
 502 module_init(irda_thread_create);
 503 module_exit(irda_thread_join);
 504
 505 MODULE_AUTHOR("Martin Diehl <info@mdiehl.de>");
 506 MODULE_DESCRIPTION("IrDA SIR core");
 507 MODULE_LICENSE("GPL");
 508