drivers/staging/comedi/drivers.c

   1 /*
   2     module/drivers.c
   3     functions for manipulating drivers
   4
   5     COMEDI - Linux Control and Measurement Device Interface
   6     Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17 */
  18
  19 #include <linux/device.h>
  20 #include <linux/module.h>
  21 #include <linux/errno.h>
  22 #include <linux/kconfig.h>
  23 #include <linux/kernel.h>
  24 #include <linux/sched.h>
  25 #include <linux/fcntl.h>
  26 #include <linux/ioport.h>
  27 #include <linux/mm.h>
  28 #include <linux/slab.h>
  29 #include <linux/highmem.h>      /* for SuSE brokenness */
  30 #include <linux/vmalloc.h>
  31 #include <linux/cdev.h>
  32 #include <linux/dma-mapping.h>
  33 #include <linux/io.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/firmware.h>
  36
  37 #include "comedidev.h"
  38 #include "comedi_internal.h"
  39
  40 struct comedi_driver *comedi_drivers;
  41 DEFINE_MUTEX(comedi_drivers_list_lock);
  42
  43 int comedi_set_hw_dev(struct comedi_device *dev, struct device *hw_dev)
  44 {
  45         if (hw_dev == dev->hw_dev)
  46                 return 0;
  47         if (dev->hw_dev != NULL)
  48                 return -EEXIST;
  49         dev->hw_dev = get_device(hw_dev);
  50         return 0;
  51 }
  52 EXPORT_SYMBOL_GPL(comedi_set_hw_dev);
  53
  54 static void comedi_clear_hw_dev(struct comedi_device *dev)
  55 {
  56         put_device(dev->hw_dev);
  57         dev->hw_dev = NULL;
  58 }
  59
  60 /**
  61  * comedi_alloc_devpriv() - Allocate memory for the device private data.
  62  * @dev: comedi_device struct
  63  * @size: size of the memory to allocate
  64  */
  65 void *comedi_alloc_devpriv(struct comedi_device *dev, size_t size)
  66 {
  67         dev->private = kzalloc(size, GFP_KERNEL);
  68         return dev->private;
  69 }
  70 EXPORT_SYMBOL_GPL(comedi_alloc_devpriv);
  71
  72 int comedi_alloc_subdevices(struct comedi_device *dev, int num_subdevices)
  73 {
  74         struct comedi_subdevice *s;
  75         int i;
  76
  77         if (num_subdevices < 1)
  78                 return -EINVAL;
  79
  80         s = kcalloc(num_subdevices, sizeof(*s), GFP_KERNEL);
  81         if (!s)
  82                 return -ENOMEM;
  83         dev->subdevices = s;
  84         dev->n_subdevices = num_subdevices;
  85
  86         for (i = 0; i < num_subdevices; ++i) {
  87                 s = &dev->subdevices[i];
  88                 s->device = dev;
  89                 s->index = i;
  90                 s->async_dma_dir = DMA_NONE;
  91                 spin_lock_init(&s->spin_lock);
  92                 s->minor = -1;
  93         }
  94         return 0;
  95 }
  96 EXPORT_SYMBOL_GPL(comedi_alloc_subdevices);
  97
  98 static void comedi_device_detach_cleanup(struct comedi_device *dev)
  99 {
 100         int i;
 101         struct comedi_subdevice *s;
 102
 103         if (dev->subdevices) {
 104                 for (i = 0; i < dev->n_subdevices; i++) {
 105                         s = &dev->subdevices[i];
 106                         if (s->runflags & SRF_FREE_SPRIV)
 107                                 kfree(s->private);
 108                         comedi_free_subdevice_minor(s);
 109                         if (s->async) {
 110                                 comedi_buf_alloc(dev, s, 0);
 111                                 kfree(s->async);
 112                         }
 113                 }
 114                 kfree(dev->subdevices);
 115                 dev->subdevices = NULL;
 116                 dev->n_subdevices = 0;
 117         }
 118         kfree(dev->private);
 119         dev->private = NULL;
 120         dev->driver = NULL;
 121         dev->board_name = NULL;
 122         dev->board_ptr = NULL;
 123         dev->iobase = 0;
 124         dev->iolen = 0;
 125         dev->ioenabled = false;
 126         dev->irq = 0;
 127         dev->read_subdev = NULL;
 128         dev->write_subdev = NULL;
 129         dev->open = NULL;
 130         dev->close = NULL;
 131         comedi_clear_hw_dev(dev);
 132 }
 133
 134 void comedi_device_detach(struct comedi_device *dev)
 135 {
 136         comedi_device_cancel_all(dev);
 137         down_write(&dev->attach_lock);
 138         dev->attached = false;
 139         dev->detach_count++;
 140         if (dev->driver)
 141                 dev->driver->detach(dev);
 142         comedi_device_detach_cleanup(dev);
 143         up_write(&dev->attach_lock);
 144 }
 145
 146 static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s)
 147 {
 148         return -EINVAL;
 149 }
 150
 151 int insn_inval(struct comedi_device *dev, struct comedi_subdevice *s,
 152                struct comedi_insn *insn, unsigned int *data)
 153 {
 154         return -EINVAL;
 155 }
 156
 157 /**
 158  * comedi_dio_insn_config() - boilerplate (*insn_config) for DIO subdevices.
 159  * @dev: comedi_device struct
 160  * @s: comedi_subdevice struct
 161  * @insn: comedi_insn struct
 162  * @data: parameters for the @insn
 163  * @mask: io_bits mask for grouped channels
 164  */
 165 int comedi_dio_insn_config(struct comedi_device *dev,
 166                            struct comedi_subdevice *s,
 167                            struct comedi_insn *insn,
 168                            unsigned int *data,
 169                            unsigned int mask)
 170 {
 171         unsigned int chan_mask = 1 << CR_CHAN(insn->chanspec);
 172
 173         if (!mask)
 174                 mask = chan_mask;
 175
 176         switch (data[0]) {
 177         case INSN_CONFIG_DIO_INPUT:
 178                 s->io_bits &= ~mask;
 179                 break;
 180
 181         case INSN_CONFIG_DIO_OUTPUT:
 182                 s->io_bits |= mask;
 183                 break;
 184
 185         case INSN_CONFIG_DIO_QUERY:
 186                 data[1] = (s->io_bits & mask) ? COMEDI_OUTPUT : COMEDI_INPUT;
 187                 return insn->n;
 188
 189         default:
 190                 return -EINVAL;
 191         }
 192
 193         return 0;
 194 }
 195 EXPORT_SYMBOL_GPL(comedi_dio_insn_config);
 196
 197 /**
 198  * comedi_dio_update_state() - update the internal state of DIO subdevices.
 199  * @s: comedi_subdevice struct
 200  * @data: the channel mask and bits to update
 201  */
 202 unsigned int comedi_dio_update_state(struct comedi_subdevice *s,
 203                                      unsigned int *data)
 204 {
 205         unsigned int chanmask = (s->n_chan < 32) ? ((1 << s->n_chan) - 1)
 206                                                  : 0xffffffff;
 207         unsigned int mask = data[0] & chanmask;
 208         unsigned int bits = data[1];
 209
 210         if (mask) {
 211                 s->state &= ~mask;
 212                 s->state |= (bits & mask);
 213         }
 214
 215         return mask;
 216 }
 217 EXPORT_SYMBOL_GPL(comedi_dio_update_state);
 218
 219 static int insn_rw_emulate_bits(struct comedi_device *dev,
 220                                 struct comedi_subdevice *s,
 221                                 struct comedi_insn *insn, unsigned int *data)
 222 {
 223         struct comedi_insn new_insn;
 224         int ret;
 225         static const unsigned channels_per_bitfield = 32;
 226
 227         unsigned chan = CR_CHAN(insn->chanspec);
 228         const unsigned base_bitfield_channel =
 229             (chan < channels_per_bitfield) ? 0 : chan;
 230         unsigned int new_data[2];
 231         memset(new_data, 0, sizeof(new_data));
 232         memset(&new_insn, 0, sizeof(new_insn));
 233         new_insn.insn = INSN_BITS;
 234         new_insn.chanspec = base_bitfield_channel;
 235         new_insn.n = 2;
 236         new_insn.subdev = insn->subdev;
 237
 238         if (insn->insn == INSN_WRITE) {
 239                 if (!(s->subdev_flags & SDF_WRITABLE))
 240                         return -EINVAL;
 241                 new_data[0] = 1 << (chan - base_bitfield_channel); /* mask */
 242                 new_data[1] = data[0] ? (1 << (chan - base_bitfield_channel))
 243                               : 0; /* bits */
 244         }
 245
 246         ret = s->insn_bits(dev, s, &new_insn, new_data);
 247         if (ret < 0)
 248                 return ret;
 249
 250         if (insn->insn == INSN_READ)
 251                 data[0] = (new_data[1] >> (chan - base_bitfield_channel)) & 1;
 252
 253         return 1;
 254 }
 255
 256 static int __comedi_device_postconfig_async(struct comedi_device *dev,
 257                                             struct comedi_subdevice *s)
 258 {
 259         struct comedi_async *async;
 260         unsigned int buf_size;
 261         int ret;
 262
 263         if ((s->subdev_flags & (SDF_CMD_READ | SDF_CMD_WRITE)) == 0) {
 264                 dev_warn(dev->class_dev,
 265                          "async subdevices must support SDF_CMD_READ or SDF_CMD_WRITE\n");
 266                 return -EINVAL;
 267         }
 268         if (!s->do_cmdtest) {
 269                 dev_warn(dev->class_dev,
 270                          "async subdevices must have a do_cmdtest() function\n");
 271                 return -EINVAL;
 272         }
 273
 274         async = kzalloc(sizeof(*async), GFP_KERNEL);
 275         if (!async)
 276                 return -ENOMEM;
 277
 278         init_waitqueue_head(&async->wait_head);
 279         async->subdevice = s;
 280         s->async = async;
 281
 282         async->max_bufsize = comedi_default_buf_maxsize_kb * 1024;
 283         buf_size = comedi_default_buf_size_kb * 1024;
 284         if (buf_size > async->max_bufsize)
 285                 buf_size = async->max_bufsize;
 286
 287         if (comedi_buf_alloc(dev, s, buf_size) < 0) {
 288                 dev_warn(dev->class_dev, "Buffer allocation failed\n");
 289                 return -ENOMEM;
 290         }
 291         if (s->buf_change) {
 292                 ret = s->buf_change(dev, s, buf_size);
 293                 if (ret < 0)
 294                         return ret;
 295         }
 296
 297         comedi_alloc_subdevice_minor(s);
 298
 299         return 0;
 300 }
 301
 302 static int __comedi_device_postconfig(struct comedi_device *dev)
 303 {
 304         struct comedi_subdevice *s;
 305         int ret;
 306         int i;
 307
 308         for (i = 0; i < dev->n_subdevices; i++) {
 309                 s = &dev->subdevices[i];
 310
 311                 if (s->type == COMEDI_SUBD_UNUSED)
 312                         continue;
 313
 314                 if (s->type == COMEDI_SUBD_DO) {
 315                         if (s->n_chan < 32)
 316                                 s->io_bits = (1 << s->n_chan) - 1;
 317                         else
 318                                 s->io_bits = 0xffffffff;
 319                 }
 320
 321                 if (s->len_chanlist == 0)
 322                         s->len_chanlist = 1;
 323
 324                 if (s->do_cmd) {
 325                         ret = __comedi_device_postconfig_async(dev, s);
 326                         if (ret)
 327                                 return ret;
 328                 }
 329
 330                 if (!s->range_table && !s->range_table_list)
 331                         s->range_table = &range_unknown;
 332
 333                 if (!s->insn_read && s->insn_bits)
 334                         s->insn_read = insn_rw_emulate_bits;
 335                 if (!s->insn_write && s->insn_bits)
 336                         s->insn_write = insn_rw_emulate_bits;
 337
 338                 if (!s->insn_read)
 339                         s->insn_read = insn_inval;
 340                 if (!s->insn_write)
 341                         s->insn_write = insn_inval;
 342                 if (!s->insn_bits)
 343                         s->insn_bits = insn_inval;
 344                 if (!s->insn_config)
 345                         s->insn_config = insn_inval;
 346
 347                 if (!s->poll)
 348                         s->poll = poll_invalid;
 349         }
 350
 351         return 0;
 352 }
 353
 354 /* do a little post-config cleanup */
 355 static int comedi_device_postconfig(struct comedi_device *dev)
 356 {
 357         int ret;
 358
 359         ret = __comedi_device_postconfig(dev);
 360         if (ret < 0)
 361                 return ret;
 362         down_write(&dev->attach_lock);
 363         dev->attached = true;
 364         up_write(&dev->attach_lock);
 365         return 0;
 366 }
 367
 368 /*
 369  * Generic recognize function for drivers that register their supported
 370  * board names.
 371  *
 372  * 'driv->board_name' points to a 'const char *' member within the
 373  * zeroth element of an array of some private board information
 374  * structure, say 'struct foo_board' containing a member 'const char
 375  * *board_name' that is initialized to point to a board name string that
 376  * is one of the candidates matched against this function's 'name'
 377  * parameter.
 378  *
 379  * 'driv->offset' is the size of the private board information
 380  * structure, say 'sizeof(struct foo_board)', and 'driv->num_names' is
 381  * the length of the array of private board information structures.
 382  *
 383  * If one of the board names in the array of private board information
 384  * structures matches the name supplied to this function, the function
 385  * returns a pointer to the pointer to the board name, otherwise it
 386  * returns NULL.  The return value ends up in the 'board_ptr' member of
 387  * a 'struct comedi_device' that the low-level comedi driver's
 388  * 'attach()' hook can convert to a point to a particular element of its
 389  * array of private board information structures by subtracting the
 390  * offset of the member that points to the board name.  (No subtraction
 391  * is required if the board name pointer is the first member of the
 392  * private board information structure, which is generally the case.)
 393  */
 394 static void *comedi_recognize(struct comedi_driver *driv, const char *name)
 395 {
 396         char **name_ptr = (char **)driv->board_name;
 397         int i;
 398
 399         for (i = 0; i < driv->num_names; i++) {
 400                 if (strcmp(*name_ptr, name) == 0)
 401                         return name_ptr;
 402                 name_ptr = (void *)name_ptr + driv->offset;
 403         }
 404
 405         return NULL;
 406 }
 407
 408 static void comedi_report_boards(struct comedi_driver *driv)
 409 {
 410         unsigned int i;
 411         const char *const *name_ptr;
 412
 413         pr_info("comedi: valid board names for %s driver are:\n",
 414                 driv->driver_name);
 415
 416         name_ptr = driv->board_name;
 417         for (i = 0; i < driv->num_names; i++) {
 418                 pr_info(" %s\n", *name_ptr);
 419                 name_ptr = (const char **)((char *)name_ptr + driv->offset);
 420         }
 421
 422         if (driv->num_names == 0)
 423                 pr_info(" %s\n", driv->driver_name);
 424 }
 425
 426 /**
 427  * comedi_load_firmware() - Request and load firmware for a device.
 428  * @dev: comedi_device struct
 429  * @hw_device: device struct for the comedi_device
 430  * @name: the name of the firmware image
 431  * @cb: callback to the upload the firmware image
 432  * @context: private context from the driver
 433  */
 434 int comedi_load_firmware(struct comedi_device *dev,
 435                          struct device *device,
 436                          const char *name,
 437                          int (*cb)(struct comedi_device *dev,
 438                                    const u8 *data, size_t size,
 439                                    unsigned long context),
 440                          unsigned long context)
 441 {
 442         const struct firmware *fw;
 443         int ret;
 444
 445         if (!cb)
 446                 return -EINVAL;
 447
 448         ret = request_firmware(&fw, name, device);
 449         if (ret == 0) {
 450                 ret = cb(dev, fw->data, fw->size, context);
 451                 release_firmware(fw);
 452         }
 453
 454         return ret < 0 ? ret : 0;
 455 }
 456 EXPORT_SYMBOL_GPL(comedi_load_firmware);
 457
 458 /**
 459  * __comedi_request_region() - Request an I/O reqion for a legacy driver.
 460  * @dev: comedi_device struct
 461  * @start: base address of the I/O reqion
 462  * @len: length of the I/O region
 463  */
 464 int __comedi_request_region(struct comedi_device *dev,
 465                             unsigned long start, unsigned long len)
 466 {
 467         if (!start) {
 468                 dev_warn(dev->class_dev,
 469                          "%s: a I/O base address must be specified\n",
 470                          dev->board_name);
 471                 return -EINVAL;
 472         }
 473
 474         if (!request_region(start, len, dev->board_name)) {
 475                 dev_warn(dev->class_dev, "%s: I/O port conflict (%#lx,%lu)\n",
 476                          dev->board_name, start, len);
 477                 return -EIO;
 478         }
 479
 480         return 0;
 481 }
 482 EXPORT_SYMBOL_GPL(__comedi_request_region);
 483
 484 /**
 485  * comedi_request_region() - Request an I/O reqion for a legacy driver.
 486  * @dev: comedi_device struct
 487  * @start: base address of the I/O reqion
 488  * @len: length of the I/O region
 489  */
 490 int comedi_request_region(struct comedi_device *dev,
 491                           unsigned long start, unsigned long len)
 492 {
 493         int ret;
 494
 495         ret = __comedi_request_region(dev, start, len);
 496         if (ret == 0) {
 497                 dev->iobase = start;
 498                 dev->iolen = len;
 499         }
 500
 501         return ret;
 502 }
 503 EXPORT_SYMBOL_GPL(comedi_request_region);
 504
 505 /**
 506  * comedi_legacy_detach() - A generic (*detach) function for legacy drivers.
 507  * @dev: comedi_device struct
 508  */
 509 void comedi_legacy_detach(struct comedi_device *dev)
 510 {
 511         if (dev->irq) {
 512                 free_irq(dev->irq, dev);
 513                 dev->irq = 0;
 514         }
 515         if (dev->iobase && dev->iolen) {
 516                 release_region(dev->iobase, dev->iolen);
 517                 dev->iobase = 0;
 518                 dev->iolen = 0;
 519         }
 520 }
 521 EXPORT_SYMBOL_GPL(comedi_legacy_detach);
 522
 523 int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 524 {
 525         struct comedi_driver *driv;
 526         int ret;
 527
 528         if (dev->attached)
 529                 return -EBUSY;
 530
 531         mutex_lock(&comedi_drivers_list_lock);
 532         for (driv = comedi_drivers; driv; driv = driv->next) {
 533                 if (!try_module_get(driv->module))
 534                         continue;
 535                 if (driv->num_names) {
 536                         dev->board_ptr = comedi_recognize(driv, it->board_name);
 537                         if (dev->board_ptr)
 538                                 break;
 539                 } else if (strcmp(driv->driver_name, it->board_name) == 0)
 540                         break;
 541                 module_put(driv->module);
 542         }
 543         if (driv == NULL) {
 544                 /*  recognize has failed if we get here */
 545                 /*  report valid board names before returning error */
 546                 for (driv = comedi_drivers; driv; driv = driv->next) {
 547                         if (!try_module_get(driv->module))
 548                                 continue;
 549                         comedi_report_boards(driv);
 550                         module_put(driv->module);
 551                 }
 552                 ret = -EIO;
 553                 goto out;
 554         }
 555         if (driv->attach == NULL) {
 556                 /* driver does not support manual configuration */
 557                 dev_warn(dev->class_dev,
 558                          "driver '%s' does not support attach using comedi_config\n",
 559                          driv->driver_name);
 560                 module_put(driv->module);
 561                 ret = -ENOSYS;
 562                 goto out;
 563         }
 564         /* initialize dev->driver here so
 565          * comedi_error() can be called from attach */
 566         dev->driver = driv;
 567         dev->board_name = dev->board_ptr ? *(const char **)dev->board_ptr
 568                                          : dev->driver->driver_name;
 569         ret = driv->attach(dev, it);
 570         if (ret >= 0)
 571                 ret = comedi_device_postconfig(dev);
 572         if (ret < 0) {
 573                 comedi_device_detach(dev);
 574                 module_put(driv->module);
 575         }
 576         /* On success, the driver module count has been incremented. */
 577 out:
 578         mutex_unlock(&comedi_drivers_list_lock);
 579         return ret;
 580 }
 581
 582 int comedi_auto_config(struct device *hardware_device,
 583                        struct comedi_driver *driver, unsigned long context)
 584 {
 585         struct comedi_device *dev;
 586         int ret;
 587
 588         if (!hardware_device) {
 589                 pr_warn("BUG! comedi_auto_config called with NULL hardware_device\n");
 590                 return -EINVAL;
 591         }
 592         if (!driver) {
 593                 dev_warn(hardware_device,
 594                          "BUG! comedi_auto_config called with NULL comedi driver\n");
 595                 return -EINVAL;
 596         }
 597
 598         if (!driver->auto_attach) {
 599                 dev_warn(hardware_device,
 600                          "BUG! comedi driver '%s' has no auto_attach handler\n",
 601                          driver->driver_name);
 602                 return -EINVAL;
 603         }
 604
 605         dev = comedi_alloc_board_minor(hardware_device);
 606         if (IS_ERR(dev)) {
 607                 dev_warn(hardware_device,
 608                          "driver '%s' could not create device.\n",
 609                          driver->driver_name);
 610                 return PTR_ERR(dev);
 611         }
 612         /* Note: comedi_alloc_board_minor() locked dev->mutex. */
 613
 614         dev->driver = driver;
 615         dev->board_name = dev->driver->driver_name;
 616         ret = driver->auto_attach(dev, context);
 617         if (ret >= 0)
 618                 ret = comedi_device_postconfig(dev);
 619         mutex_unlock(&dev->mutex);
 620
 621         if (ret < 0) {
 622                 dev_warn(hardware_device,
 623                          "driver '%s' failed to auto-configure device.\n",
 624                          driver->driver_name);
 625                 comedi_release_hardware_device(hardware_device);
 626         } else {
 627                 /*
 628                  * class_dev should be set properly here
 629                  *  after a successful auto config
 630                  */
 631                 dev_info(dev->class_dev,
 632                          "driver '%s' has successfully auto-configured '%s'.\n",
 633                          driver->driver_name, dev->board_name);
 634         }
 635         return ret;
 636 }
 637 EXPORT_SYMBOL_GPL(comedi_auto_config);
 638
 639 void comedi_auto_unconfig(struct device *hardware_device)
 640 {
 641         if (hardware_device == NULL)
 642                 return;
 643         comedi_release_hardware_device(hardware_device);
 644 }
 645 EXPORT_SYMBOL_GPL(comedi_auto_unconfig);
 646
 647 int comedi_driver_register(struct comedi_driver *driver)
 648 {
 649         mutex_lock(&comedi_drivers_list_lock);
 650         driver->next = comedi_drivers;
 651         comedi_drivers = driver;
 652         mutex_unlock(&comedi_drivers_list_lock);
 653
 654         return 0;
 655 }
 656 EXPORT_SYMBOL_GPL(comedi_driver_register);
 657
 658 void comedi_driver_unregister(struct comedi_driver *driver)
 659 {
 660         struct comedi_driver *prev;
 661         int i;
 662
 663         /* unlink the driver */
 664         mutex_lock(&comedi_drivers_list_lock);
 665         if (comedi_drivers == driver) {
 666                 comedi_drivers = driver->next;
 667         } else {
 668                 for (prev = comedi_drivers; prev->next; prev = prev->next) {
 669                         if (prev->next == driver) {
 670                                 prev->next = driver->next;
 671                                 break;
 672                         }
 673                 }
 674         }
 675         mutex_unlock(&comedi_drivers_list_lock);
 676
 677         /* check for devices using this driver */
 678         for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
 679                 struct comedi_device *dev = comedi_dev_get_from_minor(i);
 680
 681                 if (!dev)
 682                         continue;
 683
 684                 mutex_lock(&dev->mutex);
 685                 if (dev->attached && dev->driver == driver) {
 686                         if (dev->use_count)
 687                                 dev_warn(dev->class_dev,
 688                                          "BUG! detaching device with use_count=%d\n",
 689                                          dev->use_count);
 690                         comedi_device_detach(dev);
 691                 }
 692                 mutex_unlock(&dev->mutex);
 693                 comedi_dev_put(dev);
 694         }
 695 }
 696 EXPORT_SYMBOL_GPL(comedi_driver_unregister);