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                 if (current->flags & PF_FREEZE)
 139                         refrigerator(PF_FREEZE);
 140
 141                 run_irda_queue();
 142         }
 143
 144 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,35)
 145         reparent_to_init();
 146 #endif
 147         complete_and_exit(&irda_rq_queue.exit, 0);
 148         /* never reached */
 149         return 0;
 150 }
 151
 152
 153 static void flush_irda_queue(void)
 154 {
 155         if (atomic_read(&irda_rq_queue.num_pending)) {
 156
 157                 DECLARE_WAITQUEUE(wait, current);
 158
 159                 if (!list_empty(&irda_rq_queue.request_list))
 160                         run_irda_queue();
 161
 162                 set_task_state(current, TASK_UNINTERRUPTIBLE);
 163                 add_wait_queue(&irda_rq_queue.done, &wait);
 164                 if (atomic_read(&irda_rq_queue.num_pending))
 165                         schedule();
 166                 else
 167                         __set_task_state(current, TASK_RUNNING);
 168                 remove_wait_queue(&irda_rq_queue.done, &wait);
 169         }
 170 }
 171
 172 /* substate handler of the config-fsm to handle the cases where we want
 173  * to wait for transmit completion before changing the port configuration
 174  */
 175
 176 static int irda_tx_complete_fsm(struct sir_dev *dev)
 177 {
 178         struct sir_fsm *fsm = &dev->fsm;
 179         unsigned next_state, delay;
 180         unsigned bytes_left;
 181
 182         do {
 183                 next_state = fsm->substate;     /* default: stay in current substate */
 184                 delay = 0;
 185
 186                 switch(fsm->substate) {
 187
 188                 case SIRDEV_STATE_WAIT_XMIT:
 189                         if (dev->drv->chars_in_buffer)
 190                                 bytes_left = dev->drv->chars_in_buffer(dev);
 191                         else
 192                                 bytes_left = 0;
 193                         if (!bytes_left) {
 194                                 next_state = SIRDEV_STATE_WAIT_UNTIL_SENT;
 195                                 break;
 196                         }
 197
 198                         if (dev->speed > 115200)
 199                                 delay = (bytes_left*8*10000) / (dev->speed/100);
 200                         else if (dev->speed > 0)
 201                                 delay = (bytes_left*10*10000) / (dev->speed/100);
 202                         else
 203                                 delay = 0;
 204                         /* expected delay (usec) until remaining bytes are sent */
 205                         if (delay < 100) {
 206                                 udelay(delay);
 207                                 delay = 0;
 208                                 break;
 209                         }
 210                         /* sleep some longer delay (msec) */
 211                         delay = (delay+999) / 1000;
 212                         break;
 213
 214                 case SIRDEV_STATE_WAIT_UNTIL_SENT:
 215                         /* block until underlaying hardware buffer are empty */
 216                         if (dev->drv->wait_until_sent)
 217                                 dev->drv->wait_until_sent(dev);
 218                         next_state = SIRDEV_STATE_TX_DONE;
 219                         break;
 220
 221                 case SIRDEV_STATE_TX_DONE:
 222                         return 0;
 223
 224                 default:
 225                         IRDA_ERROR("%s - undefined state\n", __FUNCTION__);
 226                         return -EINVAL;
 227                 }
 228                 fsm->substate = next_state;
 229         } while (delay == 0);
 230         return delay;
 231 }
 232
 233 /*
 234  * Function irda_config_fsm
 235  *
 236  * State machine to handle the configuration of the device (and attached dongle, if any).
 237  * This handler is scheduled for execution in kIrDAd context, so we can sleep.
 238  * however, kIrDAd is shared by all sir_dev devices so we better don't sleep there too
 239  * long. Instead, for longer delays we start a timer to reschedule us later.
 240  * On entry, fsm->sem is always locked and the netdev xmit queue stopped.
 241  * Both must be unlocked/restarted on completion - but only on final exit.
 242  */
 243
 244 static void irda_config_fsm(void *data)
 245 {
 246         struct sir_dev *dev = data;
 247         struct sir_fsm *fsm = &dev->fsm;
 248         int next_state;
 249         int ret = -1;
 250         unsigned delay;
 251
 252         IRDA_DEBUG(2, "%s(), <%ld>\n", __FUNCTION__, jiffies);
 253
 254         do {
 255                 IRDA_DEBUG(3, "%s - state=0x%04x / substate=0x%04x\n",
 256                         __FUNCTION__, fsm->state, fsm->substate);
 257
 258                 next_state = fsm->state;
 259                 delay = 0;
 260
 261                 switch(fsm->state) {
 262
 263                 case SIRDEV_STATE_DONGLE_OPEN:
 264                         if (dev->dongle_drv != NULL) {
 265                                 ret = sirdev_put_dongle(dev);
 266                                 if (ret) {
 267                                         fsm->result = -EINVAL;
 268                                         next_state = SIRDEV_STATE_ERROR;
 269                                         break;
 270                                 }
 271                         }
 272
 273                         /* Initialize dongle */
 274                         ret = sirdev_get_dongle(dev, fsm->param);
 275                         if (ret) {
 276                                 fsm->result = ret;
 277                                 next_state = SIRDEV_STATE_ERROR;
 278                                 break;
 279                         }
 280
 281                         /* Dongles are powered through the modem control lines which
 282                          * were just set during open. Before resetting, let's wait for
 283                          * the power to stabilize. This is what some dongle drivers did
 284                          * in open before, while others didn't - should be safe anyway.
 285                          */
 286
 287                         delay = 50;
 288                         fsm->substate = SIRDEV_STATE_DONGLE_RESET;
 289                         next_state = SIRDEV_STATE_DONGLE_RESET;
 290
 291                         fsm->param = 9600;
 292
 293                         break;
 294
 295                 case SIRDEV_STATE_DONGLE_CLOSE:
 296                         /* shouldn't we just treat this as success=? */
 297                         if (dev->dongle_drv == NULL) {
 298                                 fsm->result = -EINVAL;
 299                                 next_state = SIRDEV_STATE_ERROR;
 300                                 break;
 301                         }
 302
 303                         ret = sirdev_put_dongle(dev);
 304                         if (ret) {
 305                                 fsm->result = ret;
 306                                 next_state = SIRDEV_STATE_ERROR;
 307                                 break;
 308                         }
 309                         next_state = SIRDEV_STATE_DONE;
 310                         break;
 311
 312                 case SIRDEV_STATE_SET_DTR_RTS:
 313                         ret = sirdev_set_dtr_rts(dev,
 314                                 (fsm->param&0x02) ? TRUE : FALSE,
 315                                 (fsm->param&0x01) ? TRUE : FALSE);
 316                         next_state = SIRDEV_STATE_DONE;
 317                         break;
 318
 319                 case SIRDEV_STATE_SET_SPEED:
 320                         fsm->substate = SIRDEV_STATE_WAIT_XMIT;
 321                         next_state = SIRDEV_STATE_DONGLE_CHECK;
 322                         break;
 323
 324                 case SIRDEV_STATE_DONGLE_CHECK:
 325                         ret = irda_tx_complete_fsm(dev);
 326                         if (ret < 0) {
 327                                 fsm->result = ret;
 328                                 next_state = SIRDEV_STATE_ERROR;
 329                                 break;
 330                         }
 331                         if ((delay=ret) != 0)
 332                                 break;
 333
 334                         if (dev->dongle_drv) {
 335                                 fsm->substate = SIRDEV_STATE_DONGLE_RESET;
 336                                 next_state = SIRDEV_STATE_DONGLE_RESET;
 337                         }
 338                         else {
 339                                 dev->speed = fsm->param;
 340                                 next_state = SIRDEV_STATE_PORT_SPEED;
 341                         }
 342                         break;
 343
 344                 case SIRDEV_STATE_DONGLE_RESET:
 345                         if (dev->dongle_drv->reset) {
 346                                 ret = dev->dongle_drv->reset(dev);
 347                                 if (ret < 0) {
 348                                         fsm->result = ret;
 349                                         next_state = SIRDEV_STATE_ERROR;
 350                                         break;
 351                                 }
 352                         }
 353                         else
 354                                 ret = 0;
 355                         if ((delay=ret) == 0) {
 356                                 /* set serial port according to dongle default speed */
 357                                 if (dev->drv->set_speed)
 358                                         dev->drv->set_speed(dev, dev->speed);
 359                                 fsm->substate = SIRDEV_STATE_DONGLE_SPEED;
 360                                 next_state = SIRDEV_STATE_DONGLE_SPEED;
 361                         }
 362                         break;
 363
 364                 case SIRDEV_STATE_DONGLE_SPEED:
 365                         if (dev->dongle_drv->reset) {
 366                                 ret = dev->dongle_drv->set_speed(dev, fsm->param);
 367                                 if (ret < 0) {
 368                                         fsm->result = ret;
 369                                         next_state = SIRDEV_STATE_ERROR;
 370                                         break;
 371                                 }
 372                         }
 373                         else
 374                                 ret = 0;
 375                         if ((delay=ret) == 0)
 376                                 next_state = SIRDEV_STATE_PORT_SPEED;
 377                         break;
 378
 379                 case SIRDEV_STATE_PORT_SPEED:
 380                         /* Finally we are ready to change the serial port speed */
 381                         if (dev->drv->set_speed)
 382                                 dev->drv->set_speed(dev, dev->speed);
 383                         dev->new_speed = 0;
 384                         next_state = SIRDEV_STATE_DONE;
 385                         break;
 386
 387                 case SIRDEV_STATE_DONE:
 388                         /* Signal network layer so it can send more frames */
 389                         netif_wake_queue(dev->netdev);
 390                         next_state = SIRDEV_STATE_COMPLETE;
 391                         break;
 392
 393                 default:
 394                         IRDA_ERROR("%s - undefined state\n", __FUNCTION__);
 395                         fsm->result = -EINVAL;
 396                         /* fall thru */
 397
 398                 case SIRDEV_STATE_ERROR:
 399                         IRDA_ERROR("%s - error: %d\n", __FUNCTION__, fsm->result);
 400
 401 #if 0   /* don't enable this before we have netdev->tx_timeout to recover */
 402                         netif_stop_queue(dev->netdev);
 403 #else
 404                         netif_wake_queue(dev->netdev);
 405 #endif
 406                         /* fall thru */
 407
 408                 case SIRDEV_STATE_COMPLETE:
 409                         /* config change finished, so we are not busy any longer */
 410                         sirdev_enable_rx(dev);
 411                         up(&fsm->sem);
 412                         return;
 413                 }
 414                 fsm->state = next_state;
 415         } while(!delay);
 416
 417         irda_queue_delayed_request(&fsm->rq, msecs_to_jiffies(delay));
 418 }
 419
 420 /* schedule some device configuration task for execution by kIrDAd
 421  * on behalf of the above state machine.
 422  * can be called from process or interrupt/tasklet context.
 423  */
 424
 425 int sirdev_schedule_request(struct sir_dev *dev, int initial_state, unsigned param)
 426 {
 427         struct sir_fsm *fsm = &dev->fsm;
 428         int xmit_was_down;
 429
 430         IRDA_DEBUG(2, "%s - state=0x%04x / param=%u\n", __FUNCTION__, initial_state, param);
 431
 432         if (down_trylock(&fsm->sem)) {
 433                 if (in_interrupt()  ||  in_atomic()  ||  irqs_disabled()) {
 434                         IRDA_DEBUG(1, "%s(), state machine busy!\n", __FUNCTION__);
 435                         return -EWOULDBLOCK;
 436                 } else
 437                         down(&fsm->sem);
 438         }
 439
 440         if (fsm->state == SIRDEV_STATE_DEAD) {
 441                 /* race with sirdev_close should never happen */
 442                 IRDA_ERROR("%s(), instance staled!\n", __FUNCTION__);
 443                 up(&fsm->sem);
 444                 return -ESTALE;         /* or better EPIPE? */
 445         }
 446
 447         xmit_was_down = netif_queue_stopped(dev->netdev);
 448         netif_stop_queue(dev->netdev);
 449         atomic_set(&dev->enable_rx, 0);
 450
 451         fsm->state = initial_state;
 452         fsm->param = param;
 453         fsm->result = 0;
 454
 455         INIT_LIST_HEAD(&fsm->rq.lh_request);
 456         fsm->rq.pending = 0;
 457         fsm->rq.func = irda_config_fsm;
 458         fsm->rq.data = dev;
 459
 460         if (!irda_queue_request(&fsm->rq)) {    /* returns 0 on error! */
 461                 atomic_set(&dev->enable_rx, 1);
 462                 if (!xmit_was_down)
 463                         netif_wake_queue(dev->netdev);
 464                 up(&fsm->sem);
 465                 return -EAGAIN;
 466         }
 467         return 0;
 468 }
 469
 470 int __init irda_thread_create(void)
 471 {
 472         struct completion startup;
 473         int pid;
 474
 475         spin_lock_init(&irda_rq_queue.lock);
 476         irda_rq_queue.thread = NULL;
 477         INIT_LIST_HEAD(&irda_rq_queue.request_list);
 478         init_waitqueue_head(&irda_rq_queue.kick);
 479         init_waitqueue_head(&irda_rq_queue.done);
 480         atomic_set(&irda_rq_queue.num_pending, 0);
 481
 482         init_completion(&startup);
 483         pid = kernel_thread(irda_thread, &startup, CLONE_FS|CLONE_FILES);
 484         if (pid <= 0)
 485                 return -EAGAIN;
 486         else
 487                 wait_for_completion(&startup);
 488
 489         return 0;
 490 }
 491
 492 void __exit irda_thread_join(void)
 493 {
 494         if (irda_rq_queue.thread) {
 495                 flush_irda_queue();
 496                 init_completion(&irda_rq_queue.exit);
 497                 irda_rq_queue.thread = NULL;
 498                 wake_up(&irda_rq_queue.kick);
 499                 wait_for_completion(&irda_rq_queue.exit);
 500         }
 501 }
 502