drivers/base/firmware_class.c

   1 /*
   2  * firmware_class.c - Multi purpose firmware loading support
   3  *
   4  * Copyright (c) 2003 Manuel Estrada Sainz
   5  *
   6  * Please see Documentation/firmware_class/ for more information.
   7  *
   8  */
   9
  10 #include <linux/capability.h>
  11 #include <linux/device.h>
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/timer.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/bitops.h>
  18 #include <linux/mutex.h>
  19 #include <linux/workqueue.h>
  20 #include <linux/highmem.h>
  21 #include <linux/firmware.h>
  22 #include <linux/slab.h>
  23 #include <linux/sched.h>
  24
  25 #define to_dev(obj) container_of(obj, struct device, kobj)
  26
  27 MODULE_AUTHOR("Manuel Estrada Sainz");
  28 MODULE_DESCRIPTION("Multi purpose firmware loading support");
  29 MODULE_LICENSE("GPL");
  30
  31 /* Builtin firmware support */
  32
  33 #ifdef CONFIG_FW_LOADER
  34
  35 extern struct builtin_fw __start_builtin_fw[];
  36 extern struct builtin_fw __end_builtin_fw[];
  37
  38 static bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
  39 {
  40         struct builtin_fw *b_fw;
  41
  42         for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
  43                 if (strcmp(name, b_fw->name) == 0) {
  44                         fw->size = b_fw->size;
  45                         fw->data = b_fw->data;
  46                         return true;
  47                 }
  48         }
  49
  50         return false;
  51 }
  52
  53 static bool fw_is_builtin_firmware(const struct firmware *fw)
  54 {
  55         struct builtin_fw *b_fw;
  56
  57         for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++)
  58                 if (fw->data == b_fw->data)
  59                         return true;
  60
  61         return false;
  62 }
  63
  64 #else /* Module case - no builtin firmware support */
  65
  66 static inline bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
  67 {
  68         return false;
  69 }
  70
  71 static inline bool fw_is_builtin_firmware(const struct firmware *fw)
  72 {
  73         return false;
  74 }
  75 #endif
  76
  77 enum {
  78         FW_STATUS_LOADING,
  79         FW_STATUS_DONE,
  80         FW_STATUS_ABORT,
  81 };
  82
  83 static int loading_timeout = 60;        /* In seconds */
  84
  85 static inline long firmware_loading_timeout(void)
  86 {
  87         return loading_timeout > 0 ? loading_timeout * HZ : MAX_SCHEDULE_TIMEOUT;
  88 }
  89
  90 /* fw_lock could be moved to 'struct firmware_priv' but since it is just
  91  * guarding for corner cases a global lock should be OK */
  92 static DEFINE_MUTEX(fw_lock);
  93
  94 struct firmware_priv {
  95         struct completion completion;
  96         struct firmware *fw;
  97         unsigned long status;
  98         struct page **pages;
  99         int nr_pages;
 100         int page_array_size;
 101         struct timer_list timeout;
 102         struct device dev;
 103         bool nowait;
 104         char fw_id[];
 105 };
 106
 107 static struct firmware_priv *to_firmware_priv(struct device *dev)
 108 {
 109         return container_of(dev, struct firmware_priv, dev);
 110 }
 111
 112 static void fw_load_abort(struct firmware_priv *fw_priv)
 113 {
 114         set_bit(FW_STATUS_ABORT, &fw_priv->status);
 115         wmb();
 116         complete(&fw_priv->completion);
 117 }
 118
 119 static ssize_t firmware_timeout_show(struct class *class,
 120                                      struct class_attribute *attr,
 121                                      char *buf)
 122 {
 123         return sprintf(buf, "%d\n", loading_timeout);
 124 }
 125
 126 /**
 127  * firmware_timeout_store - set number of seconds to wait for firmware
 128  * @class: device class pointer
 129  * @attr: device attribute pointer
 130  * @buf: buffer to scan for timeout value
 131  * @count: number of bytes in @buf
 132  *
 133  *      Sets the number of seconds to wait for the firmware.  Once
 134  *      this expires an error will be returned to the driver and no
 135  *      firmware will be provided.
 136  *
 137  *      Note: zero means 'wait forever'.
 138  **/
 139 static ssize_t firmware_timeout_store(struct class *class,
 140                                       struct class_attribute *attr,
 141                                       const char *buf, size_t count)
 142 {
 143         loading_timeout = simple_strtol(buf, NULL, 10);
 144         if (loading_timeout < 0)
 145                 loading_timeout = 0;
 146
 147         return count;
 148 }
 149
 150 static struct class_attribute firmware_class_attrs[] = {
 151         __ATTR(timeout, S_IWUSR | S_IRUGO,
 152                 firmware_timeout_show, firmware_timeout_store),
 153         __ATTR_NULL
 154 };
 155
 156 static void fw_dev_release(struct device *dev)
 157 {
 158         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 159         int i;
 160
 161         for (i = 0; i < fw_priv->nr_pages; i++)
 162                 __free_page(fw_priv->pages[i]);
 163         kfree(fw_priv->pages);
 164         kfree(fw_priv);
 165
 166         module_put(THIS_MODULE);
 167 }
 168
 169 static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
 170 {
 171         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 172
 173         if (add_uevent_var(env, "FIRMWARE=%s", fw_priv->fw_id))
 174                 return -ENOMEM;
 175         if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout))
 176                 return -ENOMEM;
 177         if (add_uevent_var(env, "ASYNC=%d", fw_priv->nowait))
 178                 return -ENOMEM;
 179
 180         return 0;
 181 }
 182
 183 static struct class firmware_class = {
 184         .name           = "firmware",
 185         .class_attrs    = firmware_class_attrs,
 186         .dev_uevent     = firmware_uevent,
 187         .dev_release    = fw_dev_release,
 188 };
 189
 190 static ssize_t firmware_loading_show(struct device *dev,
 191                                      struct device_attribute *attr, char *buf)
 192 {
 193         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 194         int loading = test_bit(FW_STATUS_LOADING, &fw_priv->status);
 195
 196         return sprintf(buf, "%d\n", loading);
 197 }
 198
 199 static void firmware_free_data(const struct firmware *fw)
 200 {
 201         int i;
 202         vunmap(fw->data);
 203         if (fw->pages) {
 204                 for (i = 0; i < PFN_UP(fw->size); i++)
 205                         __free_page(fw->pages[i]);
 206                 kfree(fw->pages);
 207         }
 208 }
 209
 210 /* Some architectures don't have PAGE_KERNEL_RO */
 211 #ifndef PAGE_KERNEL_RO
 212 #define PAGE_KERNEL_RO PAGE_KERNEL
 213 #endif
 214 /**
 215  * firmware_loading_store - set value in the 'loading' control file
 216  * @dev: device pointer
 217  * @attr: device attribute pointer
 218  * @buf: buffer to scan for loading control value
 219  * @count: number of bytes in @buf
 220  *
 221  *      The relevant values are:
 222  *
 223  *       1: Start a load, discarding any previous partial load.
 224  *       0: Conclude the load and hand the data to the driver code.
 225  *      -1: Conclude the load with an error and discard any written data.
 226  **/
 227 static ssize_t firmware_loading_store(struct device *dev,
 228                                       struct device_attribute *attr,
 229                                       const char *buf, size_t count)
 230 {
 231         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 232         int loading = simple_strtol(buf, NULL, 10);
 233         int i;
 234
 235         mutex_lock(&fw_lock);
 236
 237         if (!fw_priv->fw)
 238                 goto out;
 239
 240         switch (loading) {
 241         case 1:
 242                 firmware_free_data(fw_priv->fw);
 243                 memset(fw_priv->fw, 0, sizeof(struct firmware));
 244                 /* If the pages are not owned by 'struct firmware' */
 245                 for (i = 0; i < fw_priv->nr_pages; i++)
 246                         __free_page(fw_priv->pages[i]);
 247                 kfree(fw_priv->pages);
 248                 fw_priv->pages = NULL;
 249                 fw_priv->page_array_size = 0;
 250                 fw_priv->nr_pages = 0;
 251                 set_bit(FW_STATUS_LOADING, &fw_priv->status);
 252                 break;
 253         case 0:
 254                 if (test_bit(FW_STATUS_LOADING, &fw_priv->status)) {
 255                         vunmap(fw_priv->fw->data);
 256                         fw_priv->fw->data = vmap(fw_priv->pages,
 257                                                  fw_priv->nr_pages,
 258                                                  0, PAGE_KERNEL_RO);
 259                         if (!fw_priv->fw->data) {
 260                                 dev_err(dev, "%s: vmap() failed\n", __func__);
 261                                 goto err;
 262                         }
 263                         /* Pages are now owned by 'struct firmware' */
 264                         fw_priv->fw->pages = fw_priv->pages;
 265                         fw_priv->pages = NULL;
 266
 267                         fw_priv->page_array_size = 0;
 268                         fw_priv->nr_pages = 0;
 269                         complete(&fw_priv->completion);
 270                         clear_bit(FW_STATUS_LOADING, &fw_priv->status);
 271                         break;
 272                 }
 273                 /* fallthrough */
 274         default:
 275                 dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
 276                 /* fallthrough */
 277         case -1:
 278         err:
 279                 fw_load_abort(fw_priv);
 280                 break;
 281         }
 282 out:
 283         mutex_unlock(&fw_lock);
 284         return count;
 285 }
 286
 287 static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
 288
 289 static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
 290                                   struct bin_attribute *bin_attr,
 291                                   char *buffer, loff_t offset, size_t count)
 292 {
 293         struct device *dev = to_dev(kobj);
 294         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 295         struct firmware *fw;
 296         ssize_t ret_count;
 297
 298         mutex_lock(&fw_lock);
 299         fw = fw_priv->fw;
 300         if (!fw || test_bit(FW_STATUS_DONE, &fw_priv->status)) {
 301                 ret_count = -ENODEV;
 302                 goto out;
 303         }
 304         if (offset > fw->size) {
 305                 ret_count = 0;
 306                 goto out;
 307         }
 308         if (count > fw->size - offset)
 309                 count = fw->size - offset;
 310
 311         ret_count = count;
 312
 313         while (count) {
 314                 void *page_data;
 315                 int page_nr = offset >> PAGE_SHIFT;
 316                 int page_ofs = offset & (PAGE_SIZE-1);
 317                 int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
 318
 319                 page_data = kmap(fw_priv->pages[page_nr]);
 320
 321                 memcpy(buffer, page_data + page_ofs, page_cnt);
 322
 323                 kunmap(fw_priv->pages[page_nr]);
 324                 buffer += page_cnt;
 325                 offset += page_cnt;
 326                 count -= page_cnt;
 327         }
 328 out:
 329         mutex_unlock(&fw_lock);
 330         return ret_count;
 331 }
 332
 333 static int fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size)
 334 {
 335         int pages_needed = ALIGN(min_size, PAGE_SIZE) >> PAGE_SHIFT;
 336
 337         /* If the array of pages is too small, grow it... */
 338         if (fw_priv->page_array_size < pages_needed) {
 339                 int new_array_size = max(pages_needed,
 340                                          fw_priv->page_array_size * 2);
 341                 struct page **new_pages;
 342
 343                 new_pages = kmalloc(new_array_size * sizeof(void *),
 344                                     GFP_KERNEL);
 345                 if (!new_pages) {
 346                         fw_load_abort(fw_priv);
 347                         return -ENOMEM;
 348                 }
 349                 memcpy(new_pages, fw_priv->pages,
 350                        fw_priv->page_array_size * sizeof(void *));
 351                 memset(&new_pages[fw_priv->page_array_size], 0, sizeof(void *) *
 352                        (new_array_size - fw_priv->page_array_size));
 353                 kfree(fw_priv->pages);
 354                 fw_priv->pages = new_pages;
 355                 fw_priv->page_array_size = new_array_size;
 356         }
 357
 358         while (fw_priv->nr_pages < pages_needed) {
 359                 fw_priv->pages[fw_priv->nr_pages] =
 360                         alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
 361
 362                 if (!fw_priv->pages[fw_priv->nr_pages]) {
 363                         fw_load_abort(fw_priv);
 364                         return -ENOMEM;
 365                 }
 366                 fw_priv->nr_pages++;
 367         }
 368         return 0;
 369 }
 370
 371 /**
 372  * firmware_data_write - write method for firmware
 373  * @filp: open sysfs file
 374  * @kobj: kobject for the device
 375  * @bin_attr: bin_attr structure
 376  * @buffer: buffer being written
 377  * @offset: buffer offset for write in total data store area
 378  * @count: buffer size
 379  *
 380  *      Data written to the 'data' attribute will be later handed to
 381  *      the driver as a firmware image.
 382  **/
 383 static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
 384                                    struct bin_attribute *bin_attr,
 385                                    char *buffer, loff_t offset, size_t count)
 386 {
 387         struct device *dev = to_dev(kobj);
 388         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 389         struct firmware *fw;
 390         ssize_t retval;
 391
 392         if (!capable(CAP_SYS_RAWIO))
 393                 return -EPERM;
 394
 395         mutex_lock(&fw_lock);
 396         fw = fw_priv->fw;
 397         if (!fw || test_bit(FW_STATUS_DONE, &fw_priv->status)) {
 398                 retval = -ENODEV;
 399                 goto out;
 400         }
 401         retval = fw_realloc_buffer(fw_priv, offset + count);
 402         if (retval)
 403                 goto out;
 404
 405         retval = count;
 406
 407         while (count) {
 408                 void *page_data;
 409                 int page_nr = offset >> PAGE_SHIFT;
 410                 int page_ofs = offset & (PAGE_SIZE - 1);
 411                 int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
 412
 413                 page_data = kmap(fw_priv->pages[page_nr]);
 414
 415                 memcpy(page_data + page_ofs, buffer, page_cnt);
 416
 417                 kunmap(fw_priv->pages[page_nr]);
 418                 buffer += page_cnt;
 419                 offset += page_cnt;
 420                 count -= page_cnt;
 421         }
 422
 423         fw->size = max_t(size_t, offset, fw->size);
 424 out:
 425         mutex_unlock(&fw_lock);
 426         return retval;
 427 }
 428
 429 static struct bin_attribute firmware_attr_data = {
 430         .attr = { .name = "data", .mode = 0644 },
 431         .size = 0,
 432         .read = firmware_data_read,
 433         .write = firmware_data_write,
 434 };
 435
 436 static void firmware_class_timeout(u_long data)
 437 {
 438         struct firmware_priv *fw_priv = (struct firmware_priv *) data;
 439
 440         fw_load_abort(fw_priv);
 441 }
 442
 443 static struct firmware_priv *
 444 fw_create_instance(struct firmware *firmware, const char *fw_name,
 445                    struct device *device, bool uevent, bool nowait)
 446 {
 447         struct firmware_priv *fw_priv;
 448         struct device *f_dev;
 449
 450         fw_priv = kzalloc(sizeof(*fw_priv) + strlen(fw_name) + 1 , GFP_KERNEL);
 451         if (!fw_priv) {
 452                 dev_err(device, "%s: kmalloc failed\n", __func__);
 453                 return ERR_PTR(-ENOMEM);
 454         }
 455
 456         fw_priv->fw = firmware;
 457         fw_priv->nowait = nowait;
 458         strcpy(fw_priv->fw_id, fw_name);
 459         init_completion(&fw_priv->completion);
 460         setup_timer(&fw_priv->timeout,
 461                     firmware_class_timeout, (u_long) fw_priv);
 462
 463         f_dev = &fw_priv->dev;
 464
 465         device_initialize(f_dev);
 466         dev_set_name(f_dev, "%s", dev_name(device));
 467         f_dev->parent = device;
 468         f_dev->class = &firmware_class;
 469
 470         return fw_priv;
 471 }
 472
 473 static struct firmware_priv *
 474 _request_firmware_prepare(const struct firmware **firmware_p, const char *name,
 475                           struct device *device, bool uevent, bool nowait)
 476 {
 477         struct firmware *firmware;
 478         struct firmware_priv *fw_priv;
 479
 480         if (!firmware_p)
 481                 return ERR_PTR(-EINVAL);
 482
 483         *firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
 484         if (!firmware) {
 485                 dev_err(device, "%s: kmalloc(struct firmware) failed\n",
 486                         __func__);
 487                 return ERR_PTR(-ENOMEM);
 488         }
 489
 490         if (fw_get_builtin_firmware(firmware, name)) {
 491                 dev_dbg(device, "firmware: using built-in firmware %s\n", name);
 492                 return NULL;
 493         }
 494
 495         fw_priv = fw_create_instance(firmware, name, device, uevent, nowait);
 496         if (IS_ERR(fw_priv)) {
 497                 release_firmware(firmware);
 498                 *firmware_p = NULL;
 499         }
 500         return fw_priv;
 501 }
 502
 503 static void _request_firmware_cleanup(const struct firmware **firmware_p)
 504 {
 505         release_firmware(*firmware_p);
 506         *firmware_p = NULL;
 507 }
 508
 509 static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
 510                                   long timeout)
 511 {
 512         int retval = 0;
 513         struct device *f_dev = &fw_priv->dev;
 514
 515         dev_set_uevent_suppress(f_dev, true);
 516
 517         /* Need to pin this module until class device is destroyed */
 518         __module_get(THIS_MODULE);
 519
 520         retval = device_add(f_dev);
 521         if (retval) {
 522                 dev_err(f_dev, "%s: device_register failed\n", __func__);
 523                 goto err_put_dev;
 524         }
 525
 526         retval = device_create_bin_file(f_dev, &firmware_attr_data);
 527         if (retval) {
 528                 dev_err(f_dev, "%s: sysfs_create_bin_file failed\n", __func__);
 529                 goto err_del_dev;
 530         }
 531
 532         retval = device_create_file(f_dev, &dev_attr_loading);
 533         if (retval) {
 534                 dev_err(f_dev, "%s: device_create_file failed\n", __func__);
 535                 goto err_del_bin_attr;
 536         }
 537
 538         if (uevent) {
 539                 dev_set_uevent_suppress(f_dev, false);
 540                 dev_dbg(f_dev, "firmware: requesting %s\n", fw_priv->fw_id);
 541                 if (timeout != MAX_SCHEDULE_TIMEOUT)
 542                         mod_timer(&fw_priv->timeout,
 543                                   round_jiffies_up(jiffies + timeout));
 544
 545                 kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD);
 546         }
 547
 548         wait_for_completion(&fw_priv->completion);
 549
 550         set_bit(FW_STATUS_DONE, &fw_priv->status);
 551         del_timer_sync(&fw_priv->timeout);
 552
 553         mutex_lock(&fw_lock);
 554         if (!fw_priv->fw->size || test_bit(FW_STATUS_ABORT, &fw_priv->status))
 555                 retval = -ENOENT;
 556         fw_priv->fw = NULL;
 557         mutex_unlock(&fw_lock);
 558
 559         device_remove_file(f_dev, &dev_attr_loading);
 560 err_del_bin_attr:
 561         device_remove_bin_file(f_dev, &firmware_attr_data);
 562 err_del_dev:
 563         device_del(f_dev);
 564 err_put_dev:
 565         put_device(f_dev);
 566         return retval;
 567 }
 568
 569 /**
 570  * request_firmware: - send firmware request and wait for it
 571  * @firmware_p: pointer to firmware image
 572  * @name: name of firmware file
 573  * @device: device for which firmware is being loaded
 574  *
 575  *      @firmware_p will be used to return a firmware image by the name
 576  *      of @name for device @device.
 577  *
 578  *      Should be called from user context where sleeping is allowed.
 579  *
 580  *      @name will be used as $FIRMWARE in the uevent environment and
 581  *      should be distinctive enough not to be confused with any other
 582  *      firmware image for this or any other device.
 583  **/
 584 int
 585 request_firmware(const struct firmware **firmware_p, const char *name,
 586                  struct device *device)
 587 {
 588         struct firmware_priv *fw_priv;
 589         int ret;
 590
 591         fw_priv = _request_firmware_prepare(firmware_p, name, device, true,
 592                                             false);
 593         if (IS_ERR_OR_NULL(fw_priv))
 594                 return PTR_RET(fw_priv);
 595
 596         ret = usermodehelper_read_trylock();
 597         if (ret) {
 598                 kfree(fw_priv);
 599                 dev_err(device, "firmware: %s will not be loaded\n", name);
 600         } else {
 601                 ret = _request_firmware_load(fw_priv, true,
 602                                         firmware_loading_timeout());
 603                 usermodehelper_read_unlock();
 604         }
 605         if (ret)
 606                 _request_firmware_cleanup(firmware_p);
 607
 608         return ret;
 609 }
 610
 611 /**
 612  * release_firmware: - release the resource associated with a firmware image
 613  * @fw: firmware resource to release
 614  **/
 615 void release_firmware(const struct firmware *fw)
 616 {
 617         if (fw) {
 618                 if (!fw_is_builtin_firmware(fw))
 619                         firmware_free_data(fw);
 620                 kfree(fw);
 621         }
 622 }
 623
 624 /* Async support */
 625 struct firmware_work {
 626         struct work_struct work;
 627         struct module *module;
 628         const char *name;
 629         struct device *device;
 630         void *context;
 631         void (*cont)(const struct firmware *fw, void *context);
 632         bool uevent;
 633 };
 634
 635 static void request_firmware_work_func(struct work_struct *work)
 636 {
 637         struct firmware_work *fw_work;
 638         const struct firmware *fw;
 639         struct firmware_priv *fw_priv;
 640         long timeout;
 641         int ret;
 642
 643         fw_work = container_of(work, struct firmware_work, work);
 644         fw_priv = _request_firmware_prepare(&fw, fw_work->name, fw_work->device,
 645                         fw_work->uevent, true);
 646         if (IS_ERR_OR_NULL(fw_priv)) {
 647                 ret = PTR_RET(fw_priv);
 648                 goto out;
 649         }
 650
 651         timeout = usermodehelper_read_lock_wait(firmware_loading_timeout());
 652         if (timeout) {
 653                 ret = _request_firmware_load(fw_priv, fw_work->uevent, timeout);
 654                 usermodehelper_read_unlock();
 655         } else {
 656                 dev_dbg(fw_work->device, "firmware: %s loading timed out\n",
 657                         fw_work->name);
 658                 ret = -EAGAIN;
 659         }
 660         if (ret)
 661                 _request_firmware_cleanup(&fw);
 662
 663  out:
 664         fw_work->cont(fw, fw_work->context);
 665
 666         module_put(fw_work->module);
 667         kfree(fw_work);
 668 }
 669
 670 /**
 671  * request_firmware_nowait - asynchronous version of request_firmware
 672  * @module: module requesting the firmware
 673  * @uevent: sends uevent to copy the firmware image if this flag
 674  *      is non-zero else the firmware copy must be done manually.
 675  * @name: name of firmware file
 676  * @device: device for which firmware is being loaded
 677  * @gfp: allocation flags
 678  * @context: will be passed over to @cont, and
 679  *      @fw may be %NULL if firmware request fails.
 680  * @cont: function will be called asynchronously when the firmware
 681  *      request is over.
 682  *
 683  *      Asynchronous variant of request_firmware() for user contexts where
 684  *      it is not possible to sleep for long time. It can't be called
 685  *      in atomic contexts.
 686  **/
 687 int
 688 request_firmware_nowait(
 689         struct module *module, bool uevent,
 690         const char *name, struct device *device, gfp_t gfp, void *context,
 691         void (*cont)(const struct firmware *fw, void *context))
 692 {
 693         struct firmware_work *fw_work;
 694
 695         fw_work = kzalloc(sizeof (struct firmware_work), gfp);
 696         if (!fw_work)
 697                 return -ENOMEM;
 698
 699         fw_work->module = module;
 700         fw_work->name = name;
 701         fw_work->device = device;
 702         fw_work->context = context;
 703         fw_work->cont = cont;
 704         fw_work->uevent = uevent;
 705
 706         if (!try_module_get(module)) {
 707                 kfree(fw_work);
 708                 return -EFAULT;
 709         }
 710
 711         INIT_WORK(&fw_work->work, request_firmware_work_func);
 712         schedule_work(&fw_work->work);
 713         return 0;
 714 }
 715
 716 static int __init firmware_class_init(void)
 717 {
 718         return class_register(&firmware_class);
 719 }
 720
 721 static void __exit firmware_class_exit(void)
 722 {
 723         class_unregister(&firmware_class);
 724 }
 725
 726 fs_initcall(firmware_class_init);
 727 module_exit(firmware_class_exit);
 728
 729 EXPORT_SYMBOL(release_firmware);
 730 EXPORT_SYMBOL(request_firmware);
 731 EXPORT_SYMBOL(request_firmware_nowait);