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 MODULE_AUTHOR("Manuel Estrada Sainz");
  26 MODULE_DESCRIPTION("Multi purpose firmware loading support");
  27 MODULE_LICENSE("GPL");
  28
  29 /* Builtin firmware support */
  30
  31 #ifdef CONFIG_FW_LOADER
  32
  33 extern struct builtin_fw __start_builtin_fw[];
  34 extern struct builtin_fw __end_builtin_fw[];
  35
  36 static bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
  37 {
  38         struct builtin_fw *b_fw;
  39
  40         for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
  41                 if (strcmp(name, b_fw->name) == 0) {
  42                         fw->size = b_fw->size;
  43                         fw->data = b_fw->data;
  44                         return true;
  45                 }
  46         }
  47
  48         return false;
  49 }
  50
  51 static bool fw_is_builtin_firmware(const struct firmware *fw)
  52 {
  53         struct builtin_fw *b_fw;
  54
  55         for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++)
  56                 if (fw->data == b_fw->data)
  57                         return true;
  58
  59         return false;
  60 }
  61
  62 #else /* Module case - no builtin firmware support */
  63
  64 static inline bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
  65 {
  66         return false;
  67 }
  68
  69 static inline bool fw_is_builtin_firmware(const struct firmware *fw)
  70 {
  71         return false;
  72 }
  73 #endif
  74
  75 enum {
  76         FW_STATUS_LOADING,
  77         FW_STATUS_DONE,
  78         FW_STATUS_ABORT,
  79 };
  80
  81 static int loading_timeout = 60;        /* In seconds */
  82
  83 static inline long firmware_loading_timeout(void)
  84 {
  85         return loading_timeout > 0 ? loading_timeout * HZ : MAX_SCHEDULE_TIMEOUT;
  86 }
  87
  88 /* fw_lock could be moved to 'struct firmware_priv' but since it is just
  89  * guarding for corner cases a global lock should be OK */
  90 static DEFINE_MUTEX(fw_lock);
  91
  92 struct firmware_priv {
  93         struct completion completion;
  94         struct firmware *fw;
  95         unsigned long status;
  96         void *data;
  97         size_t size;
  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         /* free untransfered pages buffer */
 162         for (i = 0; i < fw_priv->nr_pages; i++)
 163                 __free_page(fw_priv->pages[i]);
 164         kfree(fw_priv->pages);
 165
 166         kfree(fw_priv);
 167
 168         module_put(THIS_MODULE);
 169 }
 170
 171 static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
 172 {
 173         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 174
 175         if (add_uevent_var(env, "FIRMWARE=%s", fw_priv->fw_id))
 176                 return -ENOMEM;
 177         if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout))
 178                 return -ENOMEM;
 179         if (add_uevent_var(env, "ASYNC=%d", fw_priv->nowait))
 180                 return -ENOMEM;
 181
 182         return 0;
 183 }
 184
 185 static struct class firmware_class = {
 186         .name           = "firmware",
 187         .class_attrs    = firmware_class_attrs,
 188         .dev_uevent     = firmware_uevent,
 189         .dev_release    = fw_dev_release,
 190 };
 191
 192 static ssize_t firmware_loading_show(struct device *dev,
 193                                      struct device_attribute *attr, char *buf)
 194 {
 195         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 196         int loading = test_bit(FW_STATUS_LOADING, &fw_priv->status);
 197
 198         return sprintf(buf, "%d\n", loading);
 199 }
 200
 201 /* firmware holds the ownership of pages */
 202 static void firmware_free_data(const struct firmware *fw)
 203 {
 204         int i;
 205         vunmap(fw->data);
 206         if (fw->pages) {
 207                 for (i = 0; i < PFN_UP(fw->size); i++)
 208                         __free_page(fw->pages[i]);
 209                 kfree(fw->pages);
 210         }
 211 }
 212
 213 /* Some architectures don't have PAGE_KERNEL_RO */
 214 #ifndef PAGE_KERNEL_RO
 215 #define PAGE_KERNEL_RO PAGE_KERNEL
 216 #endif
 217 /**
 218  * firmware_loading_store - set value in the 'loading' control file
 219  * @dev: device pointer
 220  * @attr: device attribute pointer
 221  * @buf: buffer to scan for loading control value
 222  * @count: number of bytes in @buf
 223  *
 224  *      The relevant values are:
 225  *
 226  *       1: Start a load, discarding any previous partial load.
 227  *       0: Conclude the load and hand the data to the driver code.
 228  *      -1: Conclude the load with an error and discard any written data.
 229  **/
 230 static ssize_t firmware_loading_store(struct device *dev,
 231                                       struct device_attribute *attr,
 232                                       const char *buf, size_t count)
 233 {
 234         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 235         int loading = simple_strtol(buf, NULL, 10);
 236         int i;
 237
 238         mutex_lock(&fw_lock);
 239
 240         if (!fw_priv->fw)
 241                 goto out;
 242
 243         switch (loading) {
 244         case 1:
 245                 /* discarding any previous partial load */
 246                 for (i = 0; i < fw_priv->nr_pages; i++)
 247                         __free_page(fw_priv->pages[i]);
 248                 kfree(fw_priv->pages);
 249                 fw_priv->pages = NULL;
 250                 fw_priv->page_array_size = 0;
 251                 fw_priv->nr_pages = 0;
 252                 set_bit(FW_STATUS_LOADING, &fw_priv->status);
 253                 break;
 254         case 0:
 255                 if (test_bit(FW_STATUS_LOADING, &fw_priv->status)) {
 256                         complete(&fw_priv->completion);
 257                         clear_bit(FW_STATUS_LOADING, &fw_priv->status);
 258                         break;
 259                 }
 260                 /* fallthrough */
 261         default:
 262                 dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
 263                 /* fallthrough */
 264         case -1:
 265                 fw_load_abort(fw_priv);
 266                 break;
 267         }
 268 out:
 269         mutex_unlock(&fw_lock);
 270         return count;
 271 }
 272
 273 static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
 274
 275 static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
 276                                   struct bin_attribute *bin_attr,
 277                                   char *buffer, loff_t offset, size_t count)
 278 {
 279         struct device *dev = kobj_to_dev(kobj);
 280         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 281         struct firmware *fw;
 282         ssize_t ret_count;
 283
 284         mutex_lock(&fw_lock);
 285         fw = fw_priv->fw;
 286         if (!fw || test_bit(FW_STATUS_DONE, &fw_priv->status)) {
 287                 ret_count = -ENODEV;
 288                 goto out;
 289         }
 290         if (offset > fw_priv->size) {
 291                 ret_count = 0;
 292                 goto out;
 293         }
 294         if (count > fw_priv->size - offset)
 295                 count = fw_priv->size - offset;
 296
 297         ret_count = count;
 298
 299         while (count) {
 300                 void *page_data;
 301                 int page_nr = offset >> PAGE_SHIFT;
 302                 int page_ofs = offset & (PAGE_SIZE-1);
 303                 int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
 304
 305                 page_data = kmap(fw_priv->pages[page_nr]);
 306
 307                 memcpy(buffer, page_data + page_ofs, page_cnt);
 308
 309                 kunmap(fw_priv->pages[page_nr]);
 310                 buffer += page_cnt;
 311                 offset += page_cnt;
 312                 count -= page_cnt;
 313         }
 314 out:
 315         mutex_unlock(&fw_lock);
 316         return ret_count;
 317 }
 318
 319 static int fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size)
 320 {
 321         int pages_needed = ALIGN(min_size, PAGE_SIZE) >> PAGE_SHIFT;
 322
 323         /* If the array of pages is too small, grow it... */
 324         if (fw_priv->page_array_size < pages_needed) {
 325                 int new_array_size = max(pages_needed,
 326                                          fw_priv->page_array_size * 2);
 327                 struct page **new_pages;
 328
 329                 new_pages = kmalloc(new_array_size * sizeof(void *),
 330                                     GFP_KERNEL);
 331                 if (!new_pages) {
 332                         fw_load_abort(fw_priv);
 333                         return -ENOMEM;
 334                 }
 335                 memcpy(new_pages, fw_priv->pages,
 336                        fw_priv->page_array_size * sizeof(void *));
 337                 memset(&new_pages[fw_priv->page_array_size], 0, sizeof(void *) *
 338                        (new_array_size - fw_priv->page_array_size));
 339                 kfree(fw_priv->pages);
 340                 fw_priv->pages = new_pages;
 341                 fw_priv->page_array_size = new_array_size;
 342         }
 343
 344         while (fw_priv->nr_pages < pages_needed) {
 345                 fw_priv->pages[fw_priv->nr_pages] =
 346                         alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
 347
 348                 if (!fw_priv->pages[fw_priv->nr_pages]) {
 349                         fw_load_abort(fw_priv);
 350                         return -ENOMEM;
 351                 }
 352                 fw_priv->nr_pages++;
 353         }
 354         return 0;
 355 }
 356
 357 /**
 358  * firmware_data_write - write method for firmware
 359  * @filp: open sysfs file
 360  * @kobj: kobject for the device
 361  * @bin_attr: bin_attr structure
 362  * @buffer: buffer being written
 363  * @offset: buffer offset for write in total data store area
 364  * @count: buffer size
 365  *
 366  *      Data written to the 'data' attribute will be later handed to
 367  *      the driver as a firmware image.
 368  **/
 369 static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
 370                                    struct bin_attribute *bin_attr,
 371                                    char *buffer, loff_t offset, size_t count)
 372 {
 373         struct device *dev = kobj_to_dev(kobj);
 374         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 375         struct firmware *fw;
 376         ssize_t retval;
 377
 378         if (!capable(CAP_SYS_RAWIO))
 379                 return -EPERM;
 380
 381         mutex_lock(&fw_lock);
 382         fw = fw_priv->fw;
 383         if (!fw || test_bit(FW_STATUS_DONE, &fw_priv->status)) {
 384                 retval = -ENODEV;
 385                 goto out;
 386         }
 387
 388         retval = fw_realloc_buffer(fw_priv, offset + count);
 389         if (retval)
 390                 goto out;
 391
 392         retval = count;
 393
 394         while (count) {
 395                 void *page_data;
 396                 int page_nr = offset >> PAGE_SHIFT;
 397                 int page_ofs = offset & (PAGE_SIZE - 1);
 398                 int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
 399
 400                 page_data = kmap(fw_priv->pages[page_nr]);
 401
 402                 memcpy(page_data + page_ofs, buffer, page_cnt);
 403
 404                 kunmap(fw_priv->pages[page_nr]);
 405                 buffer += page_cnt;
 406                 offset += page_cnt;
 407                 count -= page_cnt;
 408         }
 409
 410         fw_priv->size = max_t(size_t, offset, fw_priv->size);
 411 out:
 412         mutex_unlock(&fw_lock);
 413         return retval;
 414 }
 415
 416 static struct bin_attribute firmware_attr_data = {
 417         .attr = { .name = "data", .mode = 0644 },
 418         .size = 0,
 419         .read = firmware_data_read,
 420         .write = firmware_data_write,
 421 };
 422
 423 static void firmware_class_timeout(u_long data)
 424 {
 425         struct firmware_priv *fw_priv = (struct firmware_priv *) data;
 426
 427         fw_load_abort(fw_priv);
 428 }
 429
 430 static struct firmware_priv *
 431 fw_create_instance(struct firmware *firmware, const char *fw_name,
 432                    struct device *device, bool uevent, bool nowait)
 433 {
 434         struct firmware_priv *fw_priv;
 435         struct device *f_dev;
 436
 437         fw_priv = kzalloc(sizeof(*fw_priv) + strlen(fw_name) + 1 , GFP_KERNEL);
 438         if (!fw_priv) {
 439                 dev_err(device, "%s: kmalloc failed\n", __func__);
 440                 return ERR_PTR(-ENOMEM);
 441         }
 442
 443         fw_priv->fw = firmware;
 444         fw_priv->nowait = nowait;
 445         strcpy(fw_priv->fw_id, fw_name);
 446         init_completion(&fw_priv->completion);
 447         setup_timer(&fw_priv->timeout,
 448                     firmware_class_timeout, (u_long) fw_priv);
 449
 450         f_dev = &fw_priv->dev;
 451
 452         device_initialize(f_dev);
 453         dev_set_name(f_dev, "%s", dev_name(device));
 454         f_dev->parent = device;
 455         f_dev->class = &firmware_class;
 456
 457         return fw_priv;
 458 }
 459
 460 static struct firmware_priv *
 461 _request_firmware_prepare(const struct firmware **firmware_p, const char *name,
 462                           struct device *device, bool uevent, bool nowait)
 463 {
 464         struct firmware *firmware;
 465         struct firmware_priv *fw_priv;
 466
 467         if (!firmware_p)
 468                 return ERR_PTR(-EINVAL);
 469
 470         *firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
 471         if (!firmware) {
 472                 dev_err(device, "%s: kmalloc(struct firmware) failed\n",
 473                         __func__);
 474                 return ERR_PTR(-ENOMEM);
 475         }
 476
 477         if (fw_get_builtin_firmware(firmware, name)) {
 478                 dev_dbg(device, "firmware: using built-in firmware %s\n", name);
 479                 return NULL;
 480         }
 481
 482         fw_priv = fw_create_instance(firmware, name, device, uevent, nowait);
 483         if (IS_ERR(fw_priv)) {
 484                 release_firmware(firmware);
 485                 *firmware_p = NULL;
 486         }
 487         return fw_priv;
 488 }
 489
 490 static void _request_firmware_cleanup(const struct firmware **firmware_p)
 491 {
 492         release_firmware(*firmware_p);
 493         *firmware_p = NULL;
 494 }
 495
 496 /* transfer the ownership of pages to firmware */
 497 static int fw_set_page_data(struct firmware_priv *fw_priv)
 498 {
 499         struct firmware *fw = fw_priv->fw;
 500
 501         fw_priv->data = vmap(fw_priv->pages, fw_priv->nr_pages,
 502                                 0, PAGE_KERNEL_RO);
 503         if (!fw_priv->data)
 504                 return -ENOMEM;
 505
 506         fw->data = fw_priv->data;
 507         fw->pages = fw_priv->pages;
 508         fw->size = fw_priv->size;
 509
 510         WARN_ON(PFN_UP(fw->size) != fw_priv->nr_pages);
 511
 512         fw_priv->nr_pages = 0;
 513         fw_priv->pages = NULL;
 514         fw_priv->data = NULL;
 515
 516         return 0;
 517 }
 518
 519 static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
 520                                   long timeout)
 521 {
 522         int retval = 0;
 523         struct device *f_dev = &fw_priv->dev;
 524
 525         dev_set_uevent_suppress(f_dev, true);
 526
 527         /* Need to pin this module until class device is destroyed */
 528         __module_get(THIS_MODULE);
 529
 530         retval = device_add(f_dev);
 531         if (retval) {
 532                 dev_err(f_dev, "%s: device_register failed\n", __func__);
 533                 goto err_put_dev;
 534         }
 535
 536         retval = device_create_bin_file(f_dev, &firmware_attr_data);
 537         if (retval) {
 538                 dev_err(f_dev, "%s: sysfs_create_bin_file failed\n", __func__);
 539                 goto err_del_dev;
 540         }
 541
 542         retval = device_create_file(f_dev, &dev_attr_loading);
 543         if (retval) {
 544                 dev_err(f_dev, "%s: device_create_file failed\n", __func__);
 545                 goto err_del_bin_attr;
 546         }
 547
 548         if (uevent) {
 549                 dev_set_uevent_suppress(f_dev, false);
 550                 dev_dbg(f_dev, "firmware: requesting %s\n", fw_priv->fw_id);
 551                 if (timeout != MAX_SCHEDULE_TIMEOUT)
 552                         mod_timer(&fw_priv->timeout,
 553                                   round_jiffies_up(jiffies + timeout));
 554
 555                 kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD);
 556         }
 557
 558         wait_for_completion(&fw_priv->completion);
 559
 560         set_bit(FW_STATUS_DONE, &fw_priv->status);
 561         del_timer_sync(&fw_priv->timeout);
 562
 563         mutex_lock(&fw_lock);
 564         if (!fw_priv->size || test_bit(FW_STATUS_ABORT, &fw_priv->status))
 565                 retval = -ENOENT;
 566
 567         /* transfer pages ownership at the last minute */
 568         if (!retval)
 569                 retval = fw_set_page_data(fw_priv);
 570         fw_priv->fw = NULL;
 571         mutex_unlock(&fw_lock);
 572
 573         device_remove_file(f_dev, &dev_attr_loading);
 574 err_del_bin_attr:
 575         device_remove_bin_file(f_dev, &firmware_attr_data);
 576 err_del_dev:
 577         device_del(f_dev);
 578 err_put_dev:
 579         put_device(f_dev);
 580         return retval;
 581 }
 582
 583 /**
 584  * request_firmware: - send firmware request and wait for it
 585  * @firmware_p: pointer to firmware image
 586  * @name: name of firmware file
 587  * @device: device for which firmware is being loaded
 588  *
 589  *      @firmware_p will be used to return a firmware image by the name
 590  *      of @name for device @device.
 591  *
 592  *      Should be called from user context where sleeping is allowed.
 593  *
 594  *      @name will be used as $FIRMWARE in the uevent environment and
 595  *      should be distinctive enough not to be confused with any other
 596  *      firmware image for this or any other device.
 597  **/
 598 int
 599 request_firmware(const struct firmware **firmware_p, const char *name,
 600                  struct device *device)
 601 {
 602         struct firmware_priv *fw_priv;
 603         int ret;
 604
 605         fw_priv = _request_firmware_prepare(firmware_p, name, device, true,
 606                                             false);
 607         if (IS_ERR_OR_NULL(fw_priv))
 608                 return PTR_RET(fw_priv);
 609
 610         ret = usermodehelper_read_trylock();
 611         if (WARN_ON(ret)) {
 612                 dev_err(device, "firmware: %s will not be loaded\n", name);
 613         } else {
 614                 ret = _request_firmware_load(fw_priv, true,
 615                                         firmware_loading_timeout());
 616                 usermodehelper_read_unlock();
 617         }
 618         if (ret)
 619                 _request_firmware_cleanup(firmware_p);
 620
 621         return ret;
 622 }
 623
 624 /**
 625  * release_firmware: - release the resource associated with a firmware image
 626  * @fw: firmware resource to release
 627  **/
 628 void release_firmware(const struct firmware *fw)
 629 {
 630         if (fw) {
 631                 if (!fw_is_builtin_firmware(fw))
 632                         firmware_free_data(fw);
 633                 kfree(fw);
 634         }
 635 }
 636
 637 /* Async support */
 638 struct firmware_work {
 639         struct work_struct work;
 640         struct module *module;
 641         const char *name;
 642         struct device *device;
 643         void *context;
 644         void (*cont)(const struct firmware *fw, void *context);
 645         bool uevent;
 646 };
 647
 648 static void request_firmware_work_func(struct work_struct *work)
 649 {
 650         struct firmware_work *fw_work;
 651         const struct firmware *fw;
 652         struct firmware_priv *fw_priv;
 653         long timeout;
 654         int ret;
 655
 656         fw_work = container_of(work, struct firmware_work, work);
 657         fw_priv = _request_firmware_prepare(&fw, fw_work->name, fw_work->device,
 658                         fw_work->uevent, true);
 659         if (IS_ERR_OR_NULL(fw_priv)) {
 660                 ret = PTR_RET(fw_priv);
 661                 goto out;
 662         }
 663
 664         timeout = usermodehelper_read_lock_wait(firmware_loading_timeout());
 665         if (timeout) {
 666                 ret = _request_firmware_load(fw_priv, fw_work->uevent, timeout);
 667                 usermodehelper_read_unlock();
 668         } else {
 669                 dev_dbg(fw_work->device, "firmware: %s loading timed out\n",
 670                         fw_work->name);
 671                 ret = -EAGAIN;
 672         }
 673         if (ret)
 674                 _request_firmware_cleanup(&fw);
 675
 676  out:
 677         fw_work->cont(fw, fw_work->context);
 678
 679         module_put(fw_work->module);
 680         kfree(fw_work);
 681 }
 682
 683 /**
 684  * request_firmware_nowait - asynchronous version of request_firmware
 685  * @module: module requesting the firmware
 686  * @uevent: sends uevent to copy the firmware image if this flag
 687  *      is non-zero else the firmware copy must be done manually.
 688  * @name: name of firmware file
 689  * @device: device for which firmware is being loaded
 690  * @gfp: allocation flags
 691  * @context: will be passed over to @cont, and
 692  *      @fw may be %NULL if firmware request fails.
 693  * @cont: function will be called asynchronously when the firmware
 694  *      request is over.
 695  *
 696  *      Asynchronous variant of request_firmware() for user contexts where
 697  *      it is not possible to sleep for long time. It can't be called
 698  *      in atomic contexts.
 699  **/
 700 int
 701 request_firmware_nowait(
 702         struct module *module, bool uevent,
 703         const char *name, struct device *device, gfp_t gfp, void *context,
 704         void (*cont)(const struct firmware *fw, void *context))
 705 {
 706         struct firmware_work *fw_work;
 707
 708         fw_work = kzalloc(sizeof (struct firmware_work), gfp);
 709         if (!fw_work)
 710                 return -ENOMEM;
 711
 712         fw_work->module = module;
 713         fw_work->name = name;
 714         fw_work->device = device;
 715         fw_work->context = context;
 716         fw_work->cont = cont;
 717         fw_work->uevent = uevent;
 718
 719         if (!try_module_get(module)) {
 720                 kfree(fw_work);
 721                 return -EFAULT;
 722         }
 723
 724         INIT_WORK(&fw_work->work, request_firmware_work_func);
 725         schedule_work(&fw_work->work);
 726         return 0;
 727 }
 728
 729 static int __init firmware_class_init(void)
 730 {
 731         return class_register(&firmware_class);
 732 }
 733
 734 static void __exit firmware_class_exit(void)
 735 {
 736         class_unregister(&firmware_class);
 737 }
 738
 739 fs_initcall(firmware_class_init);
 740 module_exit(firmware_class_exit);
 741
 742 EXPORT_SYMBOL(release_firmware);
 743 EXPORT_SYMBOL(request_firmware);
 744 EXPORT_SYMBOL(request_firmware_nowait);