drivers/media/rc/lirc_dev.c

   1 /*
   2  * LIRC base driver
   3  *
   4  * by Artur Lipowski <alipowski@interia.pl>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  *
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/kernel.h>
  24 #include <linux/sched.h>
  25 #include <linux/errno.h>
  26 #include <linux/ioctl.h>
  27 #include <linux/fs.h>
  28 #include <linux/poll.h>
  29 #include <linux/completion.h>
  30 #include <linux/mutex.h>
  31 #include <linux/wait.h>
  32 #include <linux/unistd.h>
  33 #include <linux/kthread.h>
  34 #include <linux/bitops.h>
  35 #include <linux/device.h>
  36 #include <linux/cdev.h>
  37
  38 #include <media/lirc.h>
  39 #include <media/lirc_dev.h>
  40
  41 static int debug;
  42
  43 #define IRCTL_DEV_NAME  "BaseRemoteCtl"
  44 #define NOPLUG          -1
  45 #define LOGHEAD         "lirc_dev (%s[%d]): "
  46
  47 static dev_t lirc_base_dev;
  48
  49 struct irctl {
  50         struct lirc_driver d;
  51         int attached;
  52         int open;
  53
  54         struct mutex irctl_lock;
  55         struct lirc_buffer *buf;
  56         unsigned int chunk_size;
  57
  58         struct cdev *cdev;
  59
  60         struct task_struct *task;
  61         long jiffies_to_wait;
  62 };
  63
  64 static DEFINE_MUTEX(lirc_dev_lock);
  65
  66 static struct irctl *irctls[MAX_IRCTL_DEVICES];
  67
  68 /* Only used for sysfs but defined to void otherwise */
  69 static struct class *lirc_class;
  70
  71 /*  helper function
  72  *  initializes the irctl structure
  73  */
  74 static void lirc_irctl_init(struct irctl *ir)
  75 {
  76         mutex_init(&ir->irctl_lock);
  77         ir->d.minor = NOPLUG;
  78 }
  79
  80 static void lirc_irctl_cleanup(struct irctl *ir)
  81 {
  82         dev_dbg(ir->d.dev, LOGHEAD "cleaning up\n", ir->d.name, ir->d.minor);
  83
  84         device_destroy(lirc_class, MKDEV(MAJOR(lirc_base_dev), ir->d.minor));
  85
  86         if (ir->buf != ir->d.rbuf) {
  87                 lirc_buffer_free(ir->buf);
  88                 kfree(ir->buf);
  89         }
  90         ir->buf = NULL;
  91 }
  92
  93 /*  helper function
  94  *  reads key codes from driver and puts them into buffer
  95  *  returns 0 on success
  96  */
  97 static int lirc_add_to_buf(struct irctl *ir)
  98 {
  99         if (ir->d.add_to_buf) {
 100                 int res = -ENODATA;
 101                 int got_data = 0;
 102
 103                 /*
 104                  * service the device as long as it is returning
 105                  * data and we have space
 106                  */
 107 get_data:
 108                 res = ir->d.add_to_buf(ir->d.data, ir->buf);
 109                 if (res == 0) {
 110                         got_data++;
 111                         goto get_data;
 112                 }
 113
 114                 if (res == -ENODEV)
 115                         kthread_stop(ir->task);
 116
 117                 return got_data ? 0 : res;
 118         }
 119
 120         return 0;
 121 }
 122
 123 /* main function of the polling thread
 124  */
 125 static int lirc_thread(void *irctl)
 126 {
 127         struct irctl *ir = irctl;
 128
 129         dev_dbg(ir->d.dev, LOGHEAD "poll thread started\n",
 130                 ir->d.name, ir->d.minor);
 131
 132         do {
 133                 if (ir->open) {
 134                         if (ir->jiffies_to_wait) {
 135                                 set_current_state(TASK_INTERRUPTIBLE);
 136                                 schedule_timeout(ir->jiffies_to_wait);
 137                         }
 138                         if (kthread_should_stop())
 139                                 break;
 140                         if (!lirc_add_to_buf(ir))
 141                                 wake_up_interruptible(&ir->buf->wait_poll);
 142                 } else {
 143                         set_current_state(TASK_INTERRUPTIBLE);
 144                         schedule();
 145                 }
 146         } while (!kthread_should_stop());
 147
 148         dev_dbg(ir->d.dev, LOGHEAD "poll thread ended\n",
 149                 ir->d.name, ir->d.minor);
 150
 151         return 0;
 152 }
 153
 154
 155 static struct file_operations lirc_dev_fops = {
 156         .owner          = THIS_MODULE,
 157         .read           = lirc_dev_fop_read,
 158         .write          = lirc_dev_fop_write,
 159         .poll           = lirc_dev_fop_poll,
 160         .unlocked_ioctl = lirc_dev_fop_ioctl,
 161 #ifdef CONFIG_COMPAT
 162         .compat_ioctl   = lirc_dev_fop_ioctl,
 163 #endif
 164         .open           = lirc_dev_fop_open,
 165         .release        = lirc_dev_fop_close,
 166         .llseek         = noop_llseek,
 167 };
 168
 169 static int lirc_cdev_add(struct irctl *ir)
 170 {
 171         int retval = -ENOMEM;
 172         struct lirc_driver *d = &ir->d;
 173         struct cdev *cdev;
 174
 175         cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
 176         if (!cdev)
 177                 goto err_out;
 178
 179         if (d->fops) {
 180                 cdev_init(cdev, d->fops);
 181                 cdev->owner = d->owner;
 182         } else {
 183                 cdev_init(cdev, &lirc_dev_fops);
 184                 cdev->owner = THIS_MODULE;
 185         }
 186         retval = kobject_set_name(&cdev->kobj, "lirc%d", d->minor);
 187         if (retval)
 188                 goto err_out;
 189
 190         retval = cdev_add(cdev, MKDEV(MAJOR(lirc_base_dev), d->minor), 1);
 191         if (retval) {
 192                 kobject_put(&cdev->kobj);
 193                 goto err_out;
 194         }
 195
 196         ir->cdev = cdev;
 197
 198         return 0;
 199
 200 err_out:
 201         kfree(cdev);
 202         return retval;
 203 }
 204
 205 int lirc_register_driver(struct lirc_driver *d)
 206 {
 207         struct irctl *ir;
 208         int minor;
 209         int bytes_in_key;
 210         unsigned int chunk_size;
 211         unsigned int buffer_size;
 212         int err;
 213
 214         if (!d) {
 215                 printk(KERN_ERR "lirc_dev: lirc_register_driver: "
 216                        "driver pointer must be not NULL!\n");
 217                 err = -EBADRQC;
 218                 goto out;
 219         }
 220
 221         if (!d->dev) {
 222                 printk(KERN_ERR "%s: dev pointer not filled in!\n", __func__);
 223                 err = -EINVAL;
 224                 goto out;
 225         }
 226
 227         if (MAX_IRCTL_DEVICES <= d->minor) {
 228                 dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 229                         "\"minor\" must be between 0 and %d (%d)!\n",
 230                         MAX_IRCTL_DEVICES - 1, d->minor);
 231                 err = -EBADRQC;
 232                 goto out;
 233         }
 234
 235         if (1 > d->code_length || (BUFLEN * 8) < d->code_length) {
 236                 dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 237                         "code length in bits for minor (%d) "
 238                         "must be less than %d!\n",
 239                         d->minor, BUFLEN * 8);
 240                 err = -EBADRQC;
 241                 goto out;
 242         }
 243
 244         dev_dbg(d->dev, "lirc_dev: lirc_register_driver: sample_rate: %d\n",
 245                 d->sample_rate);
 246         if (d->sample_rate) {
 247                 if (2 > d->sample_rate || HZ < d->sample_rate) {
 248                         dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 249                                 "sample_rate must be between 2 and %d!\n", HZ);
 250                         err = -EBADRQC;
 251                         goto out;
 252                 }
 253                 if (!d->add_to_buf) {
 254                         dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 255                                 "add_to_buf cannot be NULL when "
 256                                 "sample_rate is set\n");
 257                         err = -EBADRQC;
 258                         goto out;
 259                 }
 260         } else if (!(d->fops && d->fops->read) && !d->rbuf) {
 261                 dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 262                         "fops->read and rbuf cannot all be NULL!\n");
 263                 err = -EBADRQC;
 264                 goto out;
 265         } else if (!d->rbuf) {
 266                 if (!(d->fops && d->fops->read && d->fops->poll &&
 267                       d->fops->unlocked_ioctl)) {
 268                         dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 269                                 "neither read, poll nor unlocked_ioctl can be NULL!\n");
 270                         err = -EBADRQC;
 271                         goto out;
 272                 }
 273         }
 274
 275         mutex_lock(&lirc_dev_lock);
 276
 277         minor = d->minor;
 278
 279         if (minor < 0) {
 280                 /* find first free slot for driver */
 281                 for (minor = 0; minor < MAX_IRCTL_DEVICES; minor++)
 282                         if (!irctls[minor])
 283                                 break;
 284                 if (MAX_IRCTL_DEVICES == minor) {
 285                         dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 286                                 "no free slots for drivers!\n");
 287                         err = -ENOMEM;
 288                         goto out_lock;
 289                 }
 290         } else if (irctls[minor]) {
 291                 dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 292                         "minor (%d) just registered!\n", minor);
 293                 err = -EBUSY;
 294                 goto out_lock;
 295         }
 296
 297         ir = kzalloc(sizeof(struct irctl), GFP_KERNEL);
 298         if (!ir) {
 299                 err = -ENOMEM;
 300                 goto out_lock;
 301         }
 302         lirc_irctl_init(ir);
 303         irctls[minor] = ir;
 304         d->minor = minor;
 305
 306         if (d->sample_rate) {
 307                 ir->jiffies_to_wait = HZ / d->sample_rate;
 308         } else {
 309                 /* it means - wait for external event in task queue */
 310                 ir->jiffies_to_wait = 0;
 311         }
 312
 313         /* some safety check 8-) */
 314         d->name[sizeof(d->name)-1] = '\0';
 315
 316         bytes_in_key = BITS_TO_LONGS(d->code_length) +
 317                         (d->code_length % 8 ? 1 : 0);
 318         buffer_size = d->buffer_size ? d->buffer_size : BUFLEN / bytes_in_key;
 319         chunk_size  = d->chunk_size  ? d->chunk_size  : bytes_in_key;
 320
 321         if (d->rbuf) {
 322                 ir->buf = d->rbuf;
 323         } else {
 324                 ir->buf = kmalloc(sizeof(struct lirc_buffer), GFP_KERNEL);
 325                 if (!ir->buf) {
 326                         err = -ENOMEM;
 327                         goto out_lock;
 328                 }
 329                 err = lirc_buffer_init(ir->buf, chunk_size, buffer_size);
 330                 if (err) {
 331                         kfree(ir->buf);
 332                         goto out_lock;
 333                 }
 334         }
 335         ir->chunk_size = ir->buf->chunk_size;
 336
 337         if (d->features == 0)
 338                 d->features = LIRC_CAN_REC_LIRCCODE;
 339
 340         ir->d = *d;
 341
 342         device_create(lirc_class, ir->d.dev,
 343                       MKDEV(MAJOR(lirc_base_dev), ir->d.minor), NULL,
 344                       "lirc%u", ir->d.minor);
 345
 346         if (d->sample_rate) {
 347                 /* try to fire up polling thread */
 348                 ir->task = kthread_run(lirc_thread, (void *)ir, "lirc_dev");
 349                 if (IS_ERR(ir->task)) {
 350                         dev_err(d->dev, "lirc_dev: lirc_register_driver: "
 351                                 "cannot run poll thread for minor = %d\n",
 352                                 d->minor);
 353                         err = -ECHILD;
 354                         goto out_sysfs;
 355                 }
 356         }
 357
 358         err = lirc_cdev_add(ir);
 359         if (err)
 360                 goto out_sysfs;
 361
 362         ir->attached = 1;
 363         mutex_unlock(&lirc_dev_lock);
 364
 365         dev_info(ir->d.dev, "lirc_dev: driver %s registered at minor = %d\n",
 366                  ir->d.name, ir->d.minor);
 367         return minor;
 368
 369 out_sysfs:
 370         device_destroy(lirc_class, MKDEV(MAJOR(lirc_base_dev), ir->d.minor));
 371 out_lock:
 372         mutex_unlock(&lirc_dev_lock);
 373 out:
 374         return err;
 375 }
 376 EXPORT_SYMBOL(lirc_register_driver);
 377
 378 int lirc_unregister_driver(int minor)
 379 {
 380         struct irctl *ir;
 381         struct cdev *cdev;
 382
 383         if (minor < 0 || minor >= MAX_IRCTL_DEVICES) {
 384                 printk(KERN_ERR "lirc_dev: %s: minor (%d) must be between "
 385                        "0 and %d!\n", __func__, minor, MAX_IRCTL_DEVICES - 1);
 386                 return -EBADRQC;
 387         }
 388
 389         ir = irctls[minor];
 390         if (!ir) {
 391                 printk(KERN_ERR "lirc_dev: %s: failed to get irctl struct "
 392                        "for minor %d!\n", __func__, minor);
 393                 return -ENOENT;
 394         }
 395
 396         cdev = ir->cdev;
 397
 398         mutex_lock(&lirc_dev_lock);
 399
 400         if (ir->d.minor != minor) {
 401                 printk(KERN_ERR "lirc_dev: %s: minor (%d) device not "
 402                        "registered!\n", __func__, minor);
 403                 mutex_unlock(&lirc_dev_lock);
 404                 return -ENOENT;
 405         }
 406
 407         /* end up polling thread */
 408         if (ir->task)
 409                 kthread_stop(ir->task);
 410
 411         dev_dbg(ir->d.dev, "lirc_dev: driver %s unregistered from minor = %d\n",
 412                 ir->d.name, ir->d.minor);
 413
 414         ir->attached = 0;
 415         if (ir->open) {
 416                 dev_dbg(ir->d.dev, LOGHEAD "releasing opened driver\n",
 417                         ir->d.name, ir->d.minor);
 418                 wake_up_interruptible(&ir->buf->wait_poll);
 419                 mutex_lock(&ir->irctl_lock);
 420                 ir->d.set_use_dec(ir->d.data);
 421                 module_put(cdev->owner);
 422                 mutex_unlock(&ir->irctl_lock);
 423         } else {
 424                 lirc_irctl_cleanup(ir);
 425                 cdev_del(cdev);
 426                 kfree(cdev);
 427                 kfree(ir);
 428                 irctls[minor] = NULL;
 429         }
 430
 431         mutex_unlock(&lirc_dev_lock);
 432
 433         return 0;
 434 }
 435 EXPORT_SYMBOL(lirc_unregister_driver);
 436
 437 int lirc_dev_fop_open(struct inode *inode, struct file *file)
 438 {
 439         struct irctl *ir;
 440         struct cdev *cdev;
 441         int retval = 0;
 442
 443         if (iminor(inode) >= MAX_IRCTL_DEVICES) {
 444                 printk(KERN_WARNING "lirc_dev [%d]: open result = -ENODEV\n",
 445                        iminor(inode));
 446                 return -ENODEV;
 447         }
 448
 449         if (mutex_lock_interruptible(&lirc_dev_lock))
 450                 return -ERESTARTSYS;
 451
 452         ir = irctls[iminor(inode)];
 453         if (!ir) {
 454                 retval = -ENODEV;
 455                 goto error;
 456         }
 457
 458         dev_dbg(ir->d.dev, LOGHEAD "open called\n", ir->d.name, ir->d.minor);
 459
 460         if (ir->d.minor == NOPLUG) {
 461                 retval = -ENODEV;
 462                 goto error;
 463         }
 464
 465         if (ir->open) {
 466                 retval = -EBUSY;
 467                 goto error;
 468         }
 469
 470         cdev = ir->cdev;
 471         if (try_module_get(cdev->owner)) {
 472                 ir->open++;
 473                 retval = ir->d.set_use_inc(ir->d.data);
 474
 475                 if (retval) {
 476                         module_put(cdev->owner);
 477                         ir->open--;
 478                 } else {
 479                         lirc_buffer_clear(ir->buf);
 480                 }
 481                 if (ir->task)
 482                         wake_up_process(ir->task);
 483         }
 484
 485 error:
 486         if (ir)
 487                 dev_dbg(ir->d.dev, LOGHEAD "open result = %d\n",
 488                         ir->d.name, ir->d.minor, retval);
 489
 490         mutex_unlock(&lirc_dev_lock);
 491
 492         nonseekable_open(inode, file);
 493
 494         return retval;
 495 }
 496 EXPORT_SYMBOL(lirc_dev_fop_open);
 497
 498 int lirc_dev_fop_close(struct inode *inode, struct file *file)
 499 {
 500         struct irctl *ir = irctls[iminor(inode)];
 501         struct cdev *cdev;
 502
 503         if (!ir) {
 504                 printk(KERN_ERR "%s: called with invalid irctl\n", __func__);
 505                 return -EINVAL;
 506         }
 507
 508         cdev = ir->cdev;
 509
 510         dev_dbg(ir->d.dev, LOGHEAD "close called\n", ir->d.name, ir->d.minor);
 511
 512         WARN_ON(mutex_lock_killable(&lirc_dev_lock));
 513
 514         ir->open--;
 515         if (ir->attached) {
 516                 ir->d.set_use_dec(ir->d.data);
 517                 module_put(cdev->owner);
 518         } else {
 519                 lirc_irctl_cleanup(ir);
 520                 cdev_del(cdev);
 521                 irctls[ir->d.minor] = NULL;
 522                 kfree(cdev);
 523                 kfree(ir);
 524         }
 525
 526         mutex_unlock(&lirc_dev_lock);
 527
 528         return 0;
 529 }
 530 EXPORT_SYMBOL(lirc_dev_fop_close);
 531
 532 unsigned int lirc_dev_fop_poll(struct file *file, poll_table *wait)
 533 {
 534         struct irctl *ir = irctls[iminor(file->f_dentry->d_inode)];
 535         unsigned int ret;
 536
 537         if (!ir) {
 538                 printk(KERN_ERR "%s: called with invalid irctl\n", __func__);
 539                 return POLLERR;
 540         }
 541
 542         dev_dbg(ir->d.dev, LOGHEAD "poll called\n", ir->d.name, ir->d.minor);
 543
 544         if (!ir->attached)
 545                 return POLLERR;
 546
 547         poll_wait(file, &ir->buf->wait_poll, wait);
 548
 549         if (ir->buf)
 550                 if (lirc_buffer_empty(ir->buf))
 551                         ret = 0;
 552                 else
 553                         ret = POLLIN | POLLRDNORM;
 554         else
 555                 ret = POLLERR;
 556
 557         dev_dbg(ir->d.dev, LOGHEAD "poll result = %d\n",
 558                 ir->d.name, ir->d.minor, ret);
 559
 560         return ret;
 561 }
 562 EXPORT_SYMBOL(lirc_dev_fop_poll);
 563
 564 long lirc_dev_fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 565 {
 566         __u32 mode;
 567         int result = 0;
 568         struct irctl *ir = irctls[iminor(file->f_dentry->d_inode)];
 569
 570         if (!ir) {
 571                 printk(KERN_ERR "lirc_dev: %s: no irctl found!\n", __func__);
 572                 return -ENODEV;
 573         }
 574
 575         dev_dbg(ir->d.dev, LOGHEAD "ioctl called (0x%x)\n",
 576                 ir->d.name, ir->d.minor, cmd);
 577
 578         if (ir->d.minor == NOPLUG || !ir->attached) {
 579                 dev_dbg(ir->d.dev, LOGHEAD "ioctl result = -ENODEV\n",
 580                         ir->d.name, ir->d.minor);
 581                 return -ENODEV;
 582         }
 583
 584         mutex_lock(&ir->irctl_lock);
 585
 586         switch (cmd) {
 587         case LIRC_GET_FEATURES:
 588                 result = put_user(ir->d.features, (__u32 *)arg);
 589                 break;
 590         case LIRC_GET_REC_MODE:
 591                 if (!(ir->d.features & LIRC_CAN_REC_MASK)) {
 592                         result = -ENOSYS;
 593                         break;
 594                 }
 595
 596                 result = put_user(LIRC_REC2MODE
 597                                   (ir->d.features & LIRC_CAN_REC_MASK),
 598                                   (__u32 *)arg);
 599                 break;
 600         case LIRC_SET_REC_MODE:
 601                 if (!(ir->d.features & LIRC_CAN_REC_MASK)) {
 602                         result = -ENOSYS;
 603                         break;
 604                 }
 605
 606                 result = get_user(mode, (__u32 *)arg);
 607                 if (!result && !(LIRC_MODE2REC(mode) & ir->d.features))
 608                         result = -EINVAL;
 609                 /*
 610                  * FIXME: We should actually set the mode somehow but
 611                  * for now, lirc_serial doesn't support mode changing either
 612                  */
 613                 break;
 614         case LIRC_GET_LENGTH:
 615                 result = put_user(ir->d.code_length, (__u32 *)arg);
 616                 break;
 617         case LIRC_GET_MIN_TIMEOUT:
 618                 if (!(ir->d.features & LIRC_CAN_SET_REC_TIMEOUT) ||
 619                     ir->d.min_timeout == 0) {
 620                         result = -ENOSYS;
 621                         break;
 622                 }
 623
 624                 result = put_user(ir->d.min_timeout, (__u32 *)arg);
 625                 break;
 626         case LIRC_GET_MAX_TIMEOUT:
 627                 if (!(ir->d.features & LIRC_CAN_SET_REC_TIMEOUT) ||
 628                     ir->d.max_timeout == 0) {
 629                         result = -ENOSYS;
 630                         break;
 631                 }
 632
 633                 result = put_user(ir->d.max_timeout, (__u32 *)arg);
 634                 break;
 635         default:
 636                 result = -EINVAL;
 637         }
 638
 639         dev_dbg(ir->d.dev, LOGHEAD "ioctl result = %d\n",
 640                 ir->d.name, ir->d.minor, result);
 641
 642         mutex_unlock(&ir->irctl_lock);
 643
 644         return result;
 645 }
 646 EXPORT_SYMBOL(lirc_dev_fop_ioctl);
 647
 648 ssize_t lirc_dev_fop_read(struct file *file,
 649                           char __user *buffer,
 650                           size_t length,
 651                           loff_t *ppos)
 652 {
 653         struct irctl *ir = irctls[iminor(file->f_dentry->d_inode)];
 654         unsigned char *buf;
 655         int ret = 0, written = 0;
 656         DECLARE_WAITQUEUE(wait, current);
 657
 658         if (!ir) {
 659                 printk(KERN_ERR "%s: called with invalid irctl\n", __func__);
 660                 return -ENODEV;
 661         }
 662
 663         dev_dbg(ir->d.dev, LOGHEAD "read called\n", ir->d.name, ir->d.minor);
 664
 665         buf = kzalloc(ir->chunk_size, GFP_KERNEL);
 666         if (!buf)
 667                 return -ENOMEM;
 668
 669         if (mutex_lock_interruptible(&ir->irctl_lock)) {
 670                 ret = -ERESTARTSYS;
 671                 goto out_unlocked;
 672         }
 673         if (!ir->attached) {
 674                 ret = -ENODEV;
 675                 goto out_locked;
 676         }
 677
 678         if (length % ir->chunk_size) {
 679                 ret = -EINVAL;
 680                 goto out_locked;
 681         }
 682
 683         /*
 684          * we add ourselves to the task queue before buffer check
 685          * to avoid losing scan code (in case when queue is awaken somewhere
 686          * between while condition checking and scheduling)
 687          */
 688         add_wait_queue(&ir->buf->wait_poll, &wait);
 689         set_current_state(TASK_INTERRUPTIBLE);
 690
 691         /*
 692          * while we didn't provide 'length' bytes, device is opened in blocking
 693          * mode and 'copy_to_user' is happy, wait for data.
 694          */
 695         while (written < length && ret == 0) {
 696                 if (lirc_buffer_empty(ir->buf)) {
 697                         /* According to the read(2) man page, 'written' can be
 698                          * returned as less than 'length', instead of blocking
 699                          * again, returning -EWOULDBLOCK, or returning
 700                          * -ERESTARTSYS */
 701                         if (written)
 702                                 break;
 703                         if (file->f_flags & O_NONBLOCK) {
 704                                 ret = -EWOULDBLOCK;
 705                                 break;
 706                         }
 707                         if (signal_pending(current)) {
 708                                 ret = -ERESTARTSYS;
 709                                 break;
 710                         }
 711
 712                         mutex_unlock(&ir->irctl_lock);
 713                         schedule();
 714                         set_current_state(TASK_INTERRUPTIBLE);
 715
 716                         if (mutex_lock_interruptible(&ir->irctl_lock)) {
 717                                 ret = -ERESTARTSYS;
 718                                 remove_wait_queue(&ir->buf->wait_poll, &wait);
 719                                 set_current_state(TASK_RUNNING);
 720                                 goto out_unlocked;
 721                         }
 722
 723                         if (!ir->attached) {
 724                                 ret = -ENODEV;
 725                                 break;
 726                         }
 727                 } else {
 728                         lirc_buffer_read(ir->buf, buf);
 729                         ret = copy_to_user((void *)buffer+written, buf,
 730                                            ir->buf->chunk_size);
 731                         if (!ret)
 732                                 written += ir->buf->chunk_size;
 733                         else
 734                                 ret = -EFAULT;
 735                 }
 736         }
 737
 738         remove_wait_queue(&ir->buf->wait_poll, &wait);
 739         set_current_state(TASK_RUNNING);
 740
 741 out_locked:
 742         mutex_unlock(&ir->irctl_lock);
 743
 744 out_unlocked:
 745         kfree(buf);
 746         dev_dbg(ir->d.dev, LOGHEAD "read result = %s (%d)\n",
 747                 ir->d.name, ir->d.minor, ret ? "<fail>" : "<ok>", ret);
 748
 749         return ret ? ret : written;
 750 }
 751 EXPORT_SYMBOL(lirc_dev_fop_read);
 752
 753 void *lirc_get_pdata(struct file *file)
 754 {
 755         void *data = NULL;
 756
 757         if (file && file->f_dentry && file->f_dentry->d_inode &&
 758             file->f_dentry->d_inode->i_rdev) {
 759                 struct irctl *ir;
 760                 ir = irctls[iminor(file->f_dentry->d_inode)];
 761                 data = ir->d.data;
 762         }
 763
 764         return data;
 765 }
 766 EXPORT_SYMBOL(lirc_get_pdata);
 767
 768
 769 ssize_t lirc_dev_fop_write(struct file *file, const char __user *buffer,
 770                            size_t length, loff_t *ppos)
 771 {
 772         struct irctl *ir = irctls[iminor(file->f_dentry->d_inode)];
 773
 774         if (!ir) {
 775                 printk(KERN_ERR "%s: called with invalid irctl\n", __func__);
 776                 return -ENODEV;
 777         }
 778
 779         dev_dbg(ir->d.dev, LOGHEAD "write called\n", ir->d.name, ir->d.minor);
 780
 781         if (!ir->attached)
 782                 return -ENODEV;
 783
 784         return -EINVAL;
 785 }
 786 EXPORT_SYMBOL(lirc_dev_fop_write);
 787
 788
 789 static int __init lirc_dev_init(void)
 790 {
 791         int retval;
 792
 793         lirc_class = class_create(THIS_MODULE, "lirc");
 794         if (IS_ERR(lirc_class)) {
 795                 retval = PTR_ERR(lirc_class);
 796                 printk(KERN_ERR "lirc_dev: class_create failed\n");
 797                 goto error;
 798         }
 799
 800         retval = alloc_chrdev_region(&lirc_base_dev, 0, MAX_IRCTL_DEVICES,
 801                                      IRCTL_DEV_NAME);
 802         if (retval) {
 803                 class_destroy(lirc_class);
 804                 printk(KERN_ERR "lirc_dev: alloc_chrdev_region failed\n");
 805                 goto error;
 806         }
 807
 808
 809         printk(KERN_INFO "lirc_dev: IR Remote Control driver registered, "
 810                "major %d \n", MAJOR(lirc_base_dev));
 811
 812 error:
 813         return retval;
 814 }
 815
 816
 817
 818 static void __exit lirc_dev_exit(void)
 819 {
 820         class_destroy(lirc_class);
 821         unregister_chrdev_region(lirc_base_dev, MAX_IRCTL_DEVICES);
 822         printk(KERN_INFO "lirc_dev: module unloaded\n");
 823 }
 824
 825 module_init(lirc_dev_init);
 826 module_exit(lirc_dev_exit);
 827
 828 MODULE_DESCRIPTION("LIRC base driver module");
 829 MODULE_AUTHOR("Artur Lipowski");
 830 MODULE_LICENSE("GPL");
 831
 832 module_param(debug, bool, S_IRUGO | S_IWUSR);
 833 MODULE_PARM_DESC(debug, "Enable debugging messages");