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         complete(&fw_priv->completion);
 116 }
 117
 118 static ssize_t firmware_timeout_show(struct class *class,
 119                                      struct class_attribute *attr,
 120                                      char *buf)
 121 {
 122         return sprintf(buf, "%d\n", loading_timeout);
 123 }
 124
 125 /**
 126  * firmware_timeout_store - set number of seconds to wait for firmware
 127  * @class: device class pointer
 128  * @attr: device attribute pointer
 129  * @buf: buffer to scan for timeout value
 130  * @count: number of bytes in @buf
 131  *
 132  *      Sets the number of seconds to wait for the firmware.  Once
 133  *      this expires an error will be returned to the driver and no
 134  *      firmware will be provided.
 135  *
 136  *      Note: zero means 'wait forever'.
 137  **/
 138 static ssize_t firmware_timeout_store(struct class *class,
 139                                       struct class_attribute *attr,
 140                                       const char *buf, size_t count)
 141 {
 142         loading_timeout = simple_strtol(buf, NULL, 10);
 143         if (loading_timeout < 0)
 144                 loading_timeout = 0;
 145
 146         return count;
 147 }
 148
 149 static struct class_attribute firmware_class_attrs[] = {
 150         __ATTR(timeout, S_IWUSR | S_IRUGO,
 151                 firmware_timeout_show, firmware_timeout_store),
 152         __ATTR_NULL
 153 };
 154
 155 static void fw_dev_release(struct device *dev)
 156 {
 157         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 158         int i;
 159
 160         /* free untransfered pages buffer */
 161         for (i = 0; i < fw_priv->nr_pages; i++)
 162                 __free_page(fw_priv->pages[i]);
 163         kfree(fw_priv->pages);
 164
 165         kfree(fw_priv);
 166
 167         module_put(THIS_MODULE);
 168 }
 169
 170 static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
 171 {
 172         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 173
 174         if (add_uevent_var(env, "FIRMWARE=%s", fw_priv->fw_id))
 175                 return -ENOMEM;
 176         if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout))
 177                 return -ENOMEM;
 178         if (add_uevent_var(env, "ASYNC=%d", fw_priv->nowait))
 179                 return -ENOMEM;
 180
 181         return 0;
 182 }
 183
 184 static struct class firmware_class = {
 185         .name           = "firmware",
 186         .class_attrs    = firmware_class_attrs,
 187         .dev_uevent     = firmware_uevent,
 188         .dev_release    = fw_dev_release,
 189 };
 190
 191 static ssize_t firmware_loading_show(struct device *dev,
 192                                      struct device_attribute *attr, char *buf)
 193 {
 194         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 195         int loading = test_bit(FW_STATUS_LOADING, &fw_priv->status);
 196
 197         return sprintf(buf, "%d\n", loading);
 198 }
 199
 200 /* firmware holds the ownership of pages */
 201 static void firmware_free_data(const struct firmware *fw)
 202 {
 203         int i;
 204         vunmap(fw->data);
 205         if (fw->pages) {
 206                 for (i = 0; i < PFN_UP(fw->size); i++)
 207                         __free_page(fw->pages[i]);
 208                 kfree(fw->pages);
 209         }
 210 }
 211
 212 /* Some architectures don't have PAGE_KERNEL_RO */
 213 #ifndef PAGE_KERNEL_RO
 214 #define PAGE_KERNEL_RO PAGE_KERNEL
 215 #endif
 216 /**
 217  * firmware_loading_store - set value in the 'loading' control file
 218  * @dev: device pointer
 219  * @attr: device attribute pointer
 220  * @buf: buffer to scan for loading control value
 221  * @count: number of bytes in @buf
 222  *
 223  *      The relevant values are:
 224  *
 225  *       1: Start a load, discarding any previous partial load.
 226  *       0: Conclude the load and hand the data to the driver code.
 227  *      -1: Conclude the load with an error and discard any written data.
 228  **/
 229 static ssize_t firmware_loading_store(struct device *dev,
 230                                       struct device_attribute *attr,
 231                                       const char *buf, size_t count)
 232 {
 233         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 234         int loading = simple_strtol(buf, NULL, 10);
 235         int i;
 236
 237         mutex_lock(&fw_lock);
 238
 239         if (!fw_priv->fw)
 240                 goto out;
 241
 242         switch (loading) {
 243         case 1:
 244                 /* discarding any previous partial load */
 245                 if (!test_bit(FW_STATUS_DONE, &fw_priv->status)) {
 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                 }
 254                 break;
 255         case 0:
 256                 if (test_bit(FW_STATUS_LOADING, &fw_priv->status)) {
 257                         set_bit(FW_STATUS_DONE, &fw_priv->status);
 258                         clear_bit(FW_STATUS_LOADING, &fw_priv->status);
 259                         complete(&fw_priv->completion);
 260                         break;
 261                 }
 262                 /* fallthrough */
 263         default:
 264                 dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
 265                 /* fallthrough */
 266         case -1:
 267                 fw_load_abort(fw_priv);
 268                 break;
 269         }
 270 out:
 271         mutex_unlock(&fw_lock);
 272         return count;
 273 }
 274
 275 static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
 276
 277 static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
 278                                   struct bin_attribute *bin_attr,
 279                                   char *buffer, loff_t offset, size_t count)
 280 {
 281         struct device *dev = kobj_to_dev(kobj);
 282         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 283         struct firmware *fw;
 284         ssize_t ret_count;
 285
 286         mutex_lock(&fw_lock);
 287         fw = fw_priv->fw;
 288         if (!fw || test_bit(FW_STATUS_DONE, &fw_priv->status)) {
 289                 ret_count = -ENODEV;
 290                 goto out;
 291         }
 292         if (offset > fw_priv->size) {
 293                 ret_count = 0;
 294                 goto out;
 295         }
 296         if (count > fw_priv->size - offset)
 297                 count = fw_priv->size - offset;
 298
 299         ret_count = count;
 300
 301         while (count) {
 302                 void *page_data;
 303                 int page_nr = offset >> PAGE_SHIFT;
 304                 int page_ofs = offset & (PAGE_SIZE-1);
 305                 int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
 306
 307                 page_data = kmap(fw_priv->pages[page_nr]);
 308
 309                 memcpy(buffer, page_data + page_ofs, page_cnt);
 310
 311                 kunmap(fw_priv->pages[page_nr]);
 312                 buffer += page_cnt;
 313                 offset += page_cnt;
 314                 count -= page_cnt;
 315         }
 316 out:
 317         mutex_unlock(&fw_lock);
 318         return ret_count;
 319 }
 320
 321 static int fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size)
 322 {
 323         int pages_needed = ALIGN(min_size, PAGE_SIZE) >> PAGE_SHIFT;
 324
 325         /* If the array of pages is too small, grow it... */
 326         if (fw_priv->page_array_size < pages_needed) {
 327                 int new_array_size = max(pages_needed,
 328                                          fw_priv->page_array_size * 2);
 329                 struct page **new_pages;
 330
 331                 new_pages = kmalloc(new_array_size * sizeof(void *),
 332                                     GFP_KERNEL);
 333                 if (!new_pages) {
 334                         fw_load_abort(fw_priv);
 335                         return -ENOMEM;
 336                 }
 337                 memcpy(new_pages, fw_priv->pages,
 338                        fw_priv->page_array_size * sizeof(void *));
 339                 memset(&new_pages[fw_priv->page_array_size], 0, sizeof(void *) *
 340                        (new_array_size - fw_priv->page_array_size));
 341                 kfree(fw_priv->pages);
 342                 fw_priv->pages = new_pages;
 343                 fw_priv->page_array_size = new_array_size;
 344         }
 345
 346         while (fw_priv->nr_pages < pages_needed) {
 347                 fw_priv->pages[fw_priv->nr_pages] =
 348                         alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
 349
 350                 if (!fw_priv->pages[fw_priv->nr_pages]) {
 351                         fw_load_abort(fw_priv);
 352                         return -ENOMEM;
 353                 }
 354                 fw_priv->nr_pages++;
 355         }
 356         return 0;
 357 }
 358
 359 /**
 360  * firmware_data_write - write method for firmware
 361  * @filp: open sysfs file
 362  * @kobj: kobject for the device
 363  * @bin_attr: bin_attr structure
 364  * @buffer: buffer being written
 365  * @offset: buffer offset for write in total data store area
 366  * @count: buffer size
 367  *
 368  *      Data written to the 'data' attribute will be later handed to
 369  *      the driver as a firmware image.
 370  **/
 371 static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
 372                                    struct bin_attribute *bin_attr,
 373                                    char *buffer, loff_t offset, size_t count)
 374 {
 375         struct device *dev = kobj_to_dev(kobj);
 376         struct firmware_priv *fw_priv = to_firmware_priv(dev);
 377         struct firmware *fw;
 378         ssize_t retval;
 379
 380         if (!capable(CAP_SYS_RAWIO))
 381                 return -EPERM;
 382
 383         mutex_lock(&fw_lock);
 384         fw = fw_priv->fw;
 385         if (!fw || test_bit(FW_STATUS_DONE, &fw_priv->status)) {
 386                 retval = -ENODEV;
 387                 goto out;
 388         }
 389
 390         retval = fw_realloc_buffer(fw_priv, offset + count);
 391         if (retval)
 392                 goto out;
 393
 394         retval = count;
 395
 396         while (count) {
 397                 void *page_data;
 398                 int page_nr = offset >> PAGE_SHIFT;
 399                 int page_ofs = offset & (PAGE_SIZE - 1);
 400                 int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
 401
 402                 page_data = kmap(fw_priv->pages[page_nr]);
 403
 404                 memcpy(page_data + page_ofs, buffer, page_cnt);
 405
 406                 kunmap(fw_priv->pages[page_nr]);
 407                 buffer += page_cnt;
 408                 offset += page_cnt;
 409                 count -= page_cnt;
 410         }
 411
 412         fw_priv->size = max_t(size_t, offset, fw_priv->size);
 413 out:
 414         mutex_unlock(&fw_lock);
 415         return retval;
 416 }
 417
 418 static struct bin_attribute firmware_attr_data = {
 419         .attr = { .name = "data", .mode = 0644 },
 420         .size = 0,
 421         .read = firmware_data_read,
 422         .write = firmware_data_write,
 423 };
 424
 425 static void firmware_class_timeout(u_long data)
 426 {
 427         struct firmware_priv *fw_priv = (struct firmware_priv *) data;
 428
 429         fw_load_abort(fw_priv);
 430 }
 431
 432 static struct firmware_priv *
 433 fw_create_instance(struct firmware *firmware, const char *fw_name,
 434                    struct device *device, bool uevent, bool nowait)
 435 {
 436         struct firmware_priv *fw_priv;
 437         struct device *f_dev;
 438
 439         fw_priv = kzalloc(sizeof(*fw_priv) + strlen(fw_name) + 1 , GFP_KERNEL);
 440         if (!fw_priv) {
 441                 dev_err(device, "%s: kmalloc failed\n", __func__);
 442                 return ERR_PTR(-ENOMEM);
 443         }
 444
 445         fw_priv->fw = firmware;
 446         fw_priv->nowait = nowait;
 447         strcpy(fw_priv->fw_id, fw_name);
 448         init_completion(&fw_priv->completion);
 449         setup_timer(&fw_priv->timeout,
 450                     firmware_class_timeout, (u_long) fw_priv);
 451
 452         f_dev = &fw_priv->dev;
 453
 454         device_initialize(f_dev);
 455         dev_set_name(f_dev, "%s", dev_name(device));
 456         f_dev->parent = device;
 457         f_dev->class = &firmware_class;
 458
 459         return fw_priv;
 460 }
 461
 462 static struct firmware_priv *
 463 _request_firmware_prepare(const struct firmware **firmware_p, const char *name,
 464                           struct device *device, bool uevent, bool nowait)
 465 {
 466         struct firmware *firmware;
 467         struct firmware_priv *fw_priv;
 468
 469         if (!firmware_p)
 470                 return ERR_PTR(-EINVAL);
 471
 472         *firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
 473         if (!firmware) {
 474                 dev_err(device, "%s: kmalloc(struct firmware) failed\n",
 475                         __func__);
 476                 return ERR_PTR(-ENOMEM);
 477         }
 478
 479         if (fw_get_builtin_firmware(firmware, name)) {
 480                 dev_dbg(device, "firmware: using built-in firmware %s\n", name);
 481                 return NULL;
 482         }
 483
 484         fw_priv = fw_create_instance(firmware, name, device, uevent, nowait);
 485         if (IS_ERR(fw_priv)) {
 486                 release_firmware(firmware);
 487                 *firmware_p = NULL;
 488         }
 489         return fw_priv;
 490 }
 491
 492 static void _request_firmware_cleanup(const struct firmware **firmware_p)
 493 {
 494         release_firmware(*firmware_p);
 495         *firmware_p = NULL;
 496 }
 497
 498 /* transfer the ownership of pages to firmware */
 499 static int fw_set_page_data(struct firmware_priv *fw_priv)
 500 {
 501         struct firmware *fw = fw_priv->fw;
 502
 503         fw_priv->data = vmap(fw_priv->pages, fw_priv->nr_pages,
 504                                 0, PAGE_KERNEL_RO);
 505         if (!fw_priv->data)
 506                 return -ENOMEM;
 507
 508         fw->data = fw_priv->data;
 509         fw->pages = fw_priv->pages;
 510         fw->size = fw_priv->size;
 511
 512         WARN_ON(PFN_UP(fw->size) != fw_priv->nr_pages);
 513
 514         fw_priv->nr_pages = 0;
 515         fw_priv->pages = NULL;
 516         fw_priv->data = NULL;
 517
 518         return 0;
 519 }
 520
 521 static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
 522                                   long timeout)
 523 {
 524         int retval = 0;
 525         struct device *f_dev = &fw_priv->dev;
 526
 527         dev_set_uevent_suppress(f_dev, true);
 528
 529         /* Need to pin this module until class device is destroyed */
 530         __module_get(THIS_MODULE);
 531
 532         retval = device_add(f_dev);
 533         if (retval) {
 534                 dev_err(f_dev, "%s: device_register failed\n", __func__);
 535                 goto err_put_dev;
 536         }
 537
 538         retval = device_create_bin_file(f_dev, &firmware_attr_data);
 539         if (retval) {
 540                 dev_err(f_dev, "%s: sysfs_create_bin_file failed\n", __func__);
 541                 goto err_del_dev;
 542         }
 543
 544         retval = device_create_file(f_dev, &dev_attr_loading);
 545         if (retval) {
 546                 dev_err(f_dev, "%s: device_create_file failed\n", __func__);
 547                 goto err_del_bin_attr;
 548         }
 549
 550         if (uevent) {
 551                 dev_set_uevent_suppress(f_dev, false);
 552                 dev_dbg(f_dev, "firmware: requesting %s\n", fw_priv->fw_id);
 553                 if (timeout != MAX_SCHEDULE_TIMEOUT)
 554                         mod_timer(&fw_priv->timeout,
 555                                   round_jiffies_up(jiffies + timeout));
 556
 557                 kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD);
 558         }
 559
 560         wait_for_completion(&fw_priv->completion);
 561
 562         del_timer_sync(&fw_priv->timeout);
 563
 564         mutex_lock(&fw_lock);
 565         if (!fw_priv->size || test_bit(FW_STATUS_ABORT, &fw_priv->status))
 566                 retval = -ENOENT;
 567
 568         /* transfer pages ownership at the last minute */
 569         if (!retval)
 570                 retval = fw_set_page_data(fw_priv);
 571         fw_priv->fw = NULL;
 572         mutex_unlock(&fw_lock);
 573
 574         device_remove_file(f_dev, &dev_attr_loading);
 575 err_del_bin_attr:
 576         device_remove_bin_file(f_dev, &firmware_attr_data);
 577 err_del_dev:
 578         device_del(f_dev);
 579 err_put_dev:
 580         put_device(f_dev);
 581         return retval;
 582 }
 583
 584 /**
 585  * request_firmware: - send firmware request and wait for it
 586  * @firmware_p: pointer to firmware image
 587  * @name: name of firmware file
 588  * @device: device for which firmware is being loaded
 589  *
 590  *      @firmware_p will be used to return a firmware image by the name
 591  *      of @name for device @device.
 592  *
 593  *      Should be called from user context where sleeping is allowed.
 594  *
 595  *      @name will be used as $FIRMWARE in the uevent environment and
 596  *      should be distinctive enough not to be confused with any other
 597  *      firmware image for this or any other device.
 598  **/
 599 int
 600 request_firmware(const struct firmware **firmware_p, const char *name,
 601                  struct device *device)
 602 {
 603         struct firmware_priv *fw_priv;
 604         int ret;
 605
 606         fw_priv = _request_firmware_prepare(firmware_p, name, device, true,
 607                                             false);
 608         if (IS_ERR_OR_NULL(fw_priv))
 609                 return PTR_RET(fw_priv);
 610
 611         ret = usermodehelper_read_trylock();
 612         if (WARN_ON(ret)) {
 613                 dev_err(device, "firmware: %s will not be loaded\n", name);
 614         } else {
 615                 ret = _request_firmware_load(fw_priv, true,
 616                                         firmware_loading_timeout());
 617                 usermodehelper_read_unlock();
 618         }
 619         if (ret)
 620                 _request_firmware_cleanup(firmware_p);
 621
 622         return ret;
 623 }
 624
 625 /**
 626  * release_firmware: - release the resource associated with a firmware image
 627  * @fw: firmware resource to release
 628  **/
 629 void release_firmware(const struct firmware *fw)
 630 {
 631         if (fw) {
 632                 if (!fw_is_builtin_firmware(fw))
 633                         firmware_free_data(fw);
 634                 kfree(fw);
 635         }
 636 }
 637
 638 /* Async support */
 639 struct firmware_work {
 640         struct work_struct work;
 641         struct module *module;
 642         const char *name;
 643         struct device *device;
 644         void *context;
 645         void (*cont)(const struct firmware *fw, void *context);
 646         bool uevent;
 647 };
 648
 649 static void request_firmware_work_func(struct work_struct *work)
 650 {
 651         struct firmware_work *fw_work;
 652         const struct firmware *fw;
 653         struct firmware_priv *fw_priv;
 654         long timeout;
 655         int ret;
 656
 657         fw_work = container_of(work, struct firmware_work, work);
 658         fw_priv = _request_firmware_prepare(&fw, fw_work->name, fw_work->device,
 659                         fw_work->uevent, true);
 660         if (IS_ERR_OR_NULL(fw_priv)) {
 661                 ret = PTR_RET(fw_priv);
 662                 goto out;
 663         }
 664
 665         timeout = usermodehelper_read_lock_wait(firmware_loading_timeout());
 666         if (timeout) {
 667                 ret = _request_firmware_load(fw_priv, fw_work->uevent, timeout);
 668                 usermodehelper_read_unlock();
 669         } else {
 670                 dev_dbg(fw_work->device, "firmware: %s loading timed out\n",
 671                         fw_work->name);
 672                 ret = -EAGAIN;
 673         }
 674         if (ret)
 675                 _request_firmware_cleanup(&fw);
 676
 677  out:
 678         fw_work->cont(fw, fw_work->context);
 679
 680         module_put(fw_work->module);
 681         kfree(fw_work);
 682 }
 683
 684 /**
 685  * request_firmware_nowait - asynchronous version of request_firmware
 686  * @module: module requesting the firmware
 687  * @uevent: sends uevent to copy the firmware image if this flag
 688  *      is non-zero else the firmware copy must be done manually.
 689  * @name: name of firmware file
 690  * @device: device for which firmware is being loaded
 691  * @gfp: allocation flags
 692  * @context: will be passed over to @cont, and
 693  *      @fw may be %NULL if firmware request fails.
 694  * @cont: function will be called asynchronously when the firmware
 695  *      request is over.
 696  *
 697  *      Asynchronous variant of request_firmware() for user contexts where
 698  *      it is not possible to sleep for long time. It can't be called
 699  *      in atomic contexts.
 700  **/
 701 int
 702 request_firmware_nowait(
 703         struct module *module, bool uevent,
 704         const char *name, struct device *device, gfp_t gfp, void *context,
 705         void (*cont)(const struct firmware *fw, void *context))
 706 {
 707         struct firmware_work *fw_work;
 708
 709         fw_work = kzalloc(sizeof (struct firmware_work), gfp);
 710         if (!fw_work)
 711                 return -ENOMEM;
 712
 713         fw_work->module = module;
 714         fw_work->name = name;
 715         fw_work->device = device;
 716         fw_work->context = context;
 717         fw_work->cont = cont;
 718         fw_work->uevent = uevent;
 719
 720         if (!try_module_get(module)) {
 721                 kfree(fw_work);
 722                 return -EFAULT;
 723         }
 724
 725         INIT_WORK(&fw_work->work, request_firmware_work_func);
 726         schedule_work(&fw_work->work);
 727         return 0;
 728 }
 729
 730 static int __init firmware_class_init(void)
 731 {
 732         return class_register(&firmware_class);
 733 }
 734
 735 static void __exit firmware_class_exit(void)
 736 {
 737         class_unregister(&firmware_class);
 738 }
 739
 740 fs_initcall(firmware_class_init);
 741 module_exit(firmware_class_exit);
 742
 743 EXPORT_SYMBOL(release_firmware);
 744 EXPORT_SYMBOL(request_firmware);
 745 EXPORT_SYMBOL(request_firmware_nowait);