git.oblomov.eu Git - linux-2.6/blob - drivers/firewire/fw-device.c

   1 /*
   2  * Device probing and sysfs code.
   3  *
   4  * Copyright (C) 2005-2006  Kristian Hoegsberg <krh@bitplanet.net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/wait.h>
  23 #include <linux/errno.h>
  24 #include <linux/kthread.h>
  25 #include <linux/device.h>
  26 #include <linux/delay.h>
  27 #include <linux/idr.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/string.h>
  30 #include <linux/rwsem.h>
  31 #include <linux/semaphore.h>
  32 #include <asm/system.h>
  33 #include <linux/ctype.h>
  34 #include "fw-transaction.h"
  35 #include "fw-topology.h"
  36 #include "fw-device.h"
  37
  38 void fw_csr_iterator_init(struct fw_csr_iterator *ci, u32 * p)
  39 {
  40         ci->p = p + 1;
  41         ci->end = ci->p + (p[0] >> 16);
  42 }
  43 EXPORT_SYMBOL(fw_csr_iterator_init);
  44
  45 int fw_csr_iterator_next(struct fw_csr_iterator *ci, int *key, int *value)
  46 {
  47         *key = *ci->p >> 24;
  48         *value = *ci->p & 0xffffff;
  49
  50         return ci->p++ < ci->end;
  51 }
  52 EXPORT_SYMBOL(fw_csr_iterator_next);
  53
  54 static int is_fw_unit(struct device *dev);
  55
  56 static int match_unit_directory(u32 * directory, const struct fw_device_id *id)
  57 {
  58         struct fw_csr_iterator ci;
  59         int key, value, match;
  60
  61         match = 0;
  62         fw_csr_iterator_init(&ci, directory);
  63         while (fw_csr_iterator_next(&ci, &key, &value)) {
  64                 if (key == CSR_VENDOR && value == id->vendor)
  65                         match |= FW_MATCH_VENDOR;
  66                 if (key == CSR_MODEL && value == id->model)
  67                         match |= FW_MATCH_MODEL;
  68                 if (key == CSR_SPECIFIER_ID && value == id->specifier_id)
  69                         match |= FW_MATCH_SPECIFIER_ID;
  70                 if (key == CSR_VERSION && value == id->version)
  71                         match |= FW_MATCH_VERSION;
  72         }
  73
  74         return (match & id->match_flags) == id->match_flags;
  75 }
  76
  77 static int fw_unit_match(struct device *dev, struct device_driver *drv)
  78 {
  79         struct fw_unit *unit = fw_unit(dev);
  80         struct fw_driver *driver = fw_driver(drv);
  81         int i;
  82
  83         /* We only allow binding to fw_units. */
  84         if (!is_fw_unit(dev))
  85                 return 0;
  86
  87         for (i = 0; driver->id_table[i].match_flags != 0; i++) {
  88                 if (match_unit_directory(unit->directory, &driver->id_table[i]))
  89                         return 1;
  90         }
  91
  92         return 0;
  93 }
  94
  95 static int get_modalias(struct fw_unit *unit, char *buffer, size_t buffer_size)
  96 {
  97         struct fw_device *device = fw_device(unit->device.parent);
  98         struct fw_csr_iterator ci;
  99
 100         int key, value;
 101         int vendor = 0;
 102         int model = 0;
 103         int specifier_id = 0;
 104         int version = 0;
 105
 106         fw_csr_iterator_init(&ci, &device->config_rom[5]);
 107         while (fw_csr_iterator_next(&ci, &key, &value)) {
 108                 switch (key) {
 109                 case CSR_VENDOR:
 110                         vendor = value;
 111                         break;
 112                 case CSR_MODEL:
 113                         model = value;
 114                         break;
 115                 }
 116         }
 117
 118         fw_csr_iterator_init(&ci, unit->directory);
 119         while (fw_csr_iterator_next(&ci, &key, &value)) {
 120                 switch (key) {
 121                 case CSR_SPECIFIER_ID:
 122                         specifier_id = value;
 123                         break;
 124                 case CSR_VERSION:
 125                         version = value;
 126                         break;
 127                 }
 128         }
 129
 130         return snprintf(buffer, buffer_size,
 131                         "ieee1394:ven%08Xmo%08Xsp%08Xver%08X",
 132                         vendor, model, specifier_id, version);
 133 }
 134
 135 static int
 136 fw_unit_uevent(struct device *dev, struct kobj_uevent_env *env)
 137 {
 138         struct fw_unit *unit = fw_unit(dev);
 139         char modalias[64];
 140
 141         get_modalias(unit, modalias, sizeof(modalias));
 142
 143         if (add_uevent_var(env, "MODALIAS=%s", modalias))
 144                 return -ENOMEM;
 145
 146         return 0;
 147 }
 148
 149 struct bus_type fw_bus_type = {
 150         .name = "firewire",
 151         .match = fw_unit_match,
 152 };
 153 EXPORT_SYMBOL(fw_bus_type);
 154
 155 static void fw_device_release(struct device *dev)
 156 {
 157         struct fw_device *device = fw_device(dev);
 158         struct fw_card *card = device->card;
 159         unsigned long flags;
 160
 161         /*
 162          * Take the card lock so we don't set this to NULL while a
 163          * FW_NODE_UPDATED callback is being handled or while the
 164          * bus manager work looks at this node.
 165          */
 166         spin_lock_irqsave(&card->lock, flags);
 167         device->node->data = NULL;
 168         spin_unlock_irqrestore(&card->lock, flags);
 169
 170         fw_node_put(device->node);
 171         kfree(device->config_rom);
 172         kfree(device);
 173         fw_card_put(card);
 174 }
 175
 176 int fw_device_enable_phys_dma(struct fw_device *device)
 177 {
 178         int generation = device->generation;
 179
 180         /* device->node_id, accessed below, must not be older than generation */
 181         smp_rmb();
 182
 183         return device->card->driver->enable_phys_dma(device->card,
 184                                                      device->node_id,
 185                                                      generation);
 186 }
 187 EXPORT_SYMBOL(fw_device_enable_phys_dma);
 188
 189 struct config_rom_attribute {
 190         struct device_attribute attr;
 191         u32 key;
 192 };
 193
 194 static ssize_t
 195 show_immediate(struct device *dev, struct device_attribute *dattr, char *buf)
 196 {
 197         struct config_rom_attribute *attr =
 198                 container_of(dattr, struct config_rom_attribute, attr);
 199         struct fw_csr_iterator ci;
 200         u32 *dir;
 201         int key, value, ret = -ENOENT;
 202
 203         down_read(&fw_device_rwsem);
 204
 205         if (is_fw_unit(dev))
 206                 dir = fw_unit(dev)->directory;
 207         else
 208                 dir = fw_device(dev)->config_rom + 5;
 209
 210         fw_csr_iterator_init(&ci, dir);
 211         while (fw_csr_iterator_next(&ci, &key, &value))
 212                 if (attr->key == key) {
 213                         ret = snprintf(buf, buf ? PAGE_SIZE : 0,
 214                                        "0x%06x\n", value);
 215                         break;
 216                 }
 217
 218         up_read(&fw_device_rwsem);
 219
 220         return ret;
 221 }
 222
 223 #define IMMEDIATE_ATTR(name, key)                               \
 224         { __ATTR(name, S_IRUGO, show_immediate, NULL), key }
 225
 226 static ssize_t
 227 show_text_leaf(struct device *dev, struct device_attribute *dattr, char *buf)
 228 {
 229         struct config_rom_attribute *attr =
 230                 container_of(dattr, struct config_rom_attribute, attr);
 231         struct fw_csr_iterator ci;
 232         u32 *dir, *block = NULL, *p, *end;
 233         int length, key, value, last_key = 0, ret = -ENOENT;
 234         char *b;
 235
 236         down_read(&fw_device_rwsem);
 237
 238         if (is_fw_unit(dev))
 239                 dir = fw_unit(dev)->directory;
 240         else
 241                 dir = fw_device(dev)->config_rom + 5;
 242
 243         fw_csr_iterator_init(&ci, dir);
 244         while (fw_csr_iterator_next(&ci, &key, &value)) {
 245                 if (attr->key == last_key &&
 246                     key == (CSR_DESCRIPTOR | CSR_LEAF))
 247                         block = ci.p - 1 + value;
 248                 last_key = key;
 249         }
 250
 251         if (block == NULL)
 252                 goto out;
 253
 254         length = min(block[0] >> 16, 256U);
 255         if (length < 3)
 256                 goto out;
 257
 258         if (block[1] != 0 || block[2] != 0)
 259                 /* Unknown encoding. */
 260                 goto out;
 261
 262         if (buf == NULL) {
 263                 ret = length * 4;
 264                 goto out;
 265         }
 266
 267         b = buf;
 268         end = &block[length + 1];
 269         for (p = &block[3]; p < end; p++, b += 4)
 270                 * (u32 *) b = (__force u32) __cpu_to_be32(*p);
 271
 272         /* Strip trailing whitespace and add newline. */
 273         while (b--, (isspace(*b) || *b == '\0') && b > buf);
 274         strcpy(b + 1, "\n");
 275         ret = b + 2 - buf;
 276  out:
 277         up_read(&fw_device_rwsem);
 278
 279         return ret;
 280 }
 281
 282 #define TEXT_LEAF_ATTR(name, key)                               \
 283         { __ATTR(name, S_IRUGO, show_text_leaf, NULL), key }
 284
 285 static struct config_rom_attribute config_rom_attributes[] = {
 286         IMMEDIATE_ATTR(vendor, CSR_VENDOR),
 287         IMMEDIATE_ATTR(hardware_version, CSR_HARDWARE_VERSION),
 288         IMMEDIATE_ATTR(specifier_id, CSR_SPECIFIER_ID),
 289         IMMEDIATE_ATTR(version, CSR_VERSION),
 290         IMMEDIATE_ATTR(model, CSR_MODEL),
 291         TEXT_LEAF_ATTR(vendor_name, CSR_VENDOR),
 292         TEXT_LEAF_ATTR(model_name, CSR_MODEL),
 293         TEXT_LEAF_ATTR(hardware_version_name, CSR_HARDWARE_VERSION),
 294 };
 295
 296 static void
 297 init_fw_attribute_group(struct device *dev,
 298                         struct device_attribute *attrs,
 299                         struct fw_attribute_group *group)
 300 {
 301         struct device_attribute *attr;
 302         int i, j;
 303
 304         for (j = 0; attrs[j].attr.name != NULL; j++)
 305                 group->attrs[j] = &attrs[j].attr;
 306
 307         for (i = 0; i < ARRAY_SIZE(config_rom_attributes); i++) {
 308                 attr = &config_rom_attributes[i].attr;
 309                 if (attr->show(dev, attr, NULL) < 0)
 310                         continue;
 311                 group->attrs[j++] = &attr->attr;
 312         }
 313
 314         BUG_ON(j >= ARRAY_SIZE(group->attrs));
 315         group->attrs[j++] = NULL;
 316         group->groups[0] = &group->group;
 317         group->groups[1] = NULL;
 318         group->group.attrs = group->attrs;
 319         dev->groups = group->groups;
 320 }
 321
 322 static ssize_t
 323 modalias_show(struct device *dev,
 324               struct device_attribute *attr, char *buf)
 325 {
 326         struct fw_unit *unit = fw_unit(dev);
 327         int length;
 328
 329         length = get_modalias(unit, buf, PAGE_SIZE);
 330         strcpy(buf + length, "\n");
 331
 332         return length + 1;
 333 }
 334
 335 static ssize_t
 336 rom_index_show(struct device *dev,
 337                struct device_attribute *attr, char *buf)
 338 {
 339         struct fw_device *device = fw_device(dev->parent);
 340         struct fw_unit *unit = fw_unit(dev);
 341
 342         return snprintf(buf, PAGE_SIZE, "%d\n",
 343                         (int)(unit->directory - device->config_rom));
 344 }
 345
 346 static struct device_attribute fw_unit_attributes[] = {
 347         __ATTR_RO(modalias),
 348         __ATTR_RO(rom_index),
 349         __ATTR_NULL,
 350 };
 351
 352 static ssize_t
 353 config_rom_show(struct device *dev, struct device_attribute *attr, char *buf)
 354 {
 355         struct fw_device *device = fw_device(dev);
 356         size_t length;
 357
 358         down_read(&fw_device_rwsem);
 359         length = device->config_rom_length * 4;
 360         memcpy(buf, device->config_rom, length);
 361         up_read(&fw_device_rwsem);
 362
 363         return length;
 364 }
 365
 366 static ssize_t
 367 guid_show(struct device *dev, struct device_attribute *attr, char *buf)
 368 {
 369         struct fw_device *device = fw_device(dev);
 370         int ret;
 371
 372         down_read(&fw_device_rwsem);
 373         ret = snprintf(buf, PAGE_SIZE, "0x%08x%08x\n",
 374                        device->config_rom[3], device->config_rom[4]);
 375         up_read(&fw_device_rwsem);
 376
 377         return ret;
 378 }
 379
 380 static struct device_attribute fw_device_attributes[] = {
 381         __ATTR_RO(config_rom),
 382         __ATTR_RO(guid),
 383         __ATTR_NULL,
 384 };
 385
 386 static int
 387 read_rom(struct fw_device *device, int generation, int index, u32 *data)
 388 {
 389         int rcode;
 390
 391         /* device->node_id, accessed below, must not be older than generation */
 392         smp_rmb();
 393
 394         rcode = fw_run_transaction(device->card, TCODE_READ_QUADLET_REQUEST,
 395                         device->node_id, generation, device->max_speed,
 396                         (CSR_REGISTER_BASE | CSR_CONFIG_ROM) + index * 4,
 397                         data, 4);
 398         be32_to_cpus(data);
 399
 400         return rcode;
 401 }
 402
 403 #define READ_BIB_ROM_SIZE       256
 404 #define READ_BIB_STACK_SIZE     16
 405
 406 /*
 407  * Read the bus info block, perform a speed probe, and read all of the rest of
 408  * the config ROM.  We do all this with a cached bus generation.  If the bus
 409  * generation changes under us, read_bus_info_block will fail and get retried.
 410  * It's better to start all over in this case because the node from which we
 411  * are reading the ROM may have changed the ROM during the reset.
 412  */
 413 static int read_bus_info_block(struct fw_device *device, int generation)
 414 {
 415         u32 *rom, *stack, *old_rom, *new_rom;
 416         u32 sp, key;
 417         int i, end, length, ret = -1;
 418
 419         rom = kmalloc(sizeof(*rom) * READ_BIB_ROM_SIZE +
 420                       sizeof(*stack) * READ_BIB_STACK_SIZE, GFP_KERNEL);
 421         if (rom == NULL)
 422                 return -ENOMEM;
 423
 424         stack = &rom[READ_BIB_ROM_SIZE];
 425
 426         device->max_speed = SCODE_100;
 427
 428         /* First read the bus info block. */
 429         for (i = 0; i < 5; i++) {
 430                 if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
 431                         goto out;
 432                 /*
 433                  * As per IEEE1212 7.2, during power-up, devices can
 434                  * reply with a 0 for the first quadlet of the config
 435                  * rom to indicate that they are booting (for example,
 436                  * if the firmware is on the disk of a external
 437                  * harddisk).  In that case we just fail, and the
 438                  * retry mechanism will try again later.
 439                  */
 440                 if (i == 0 && rom[i] == 0)
 441                         goto out;
 442         }
 443
 444         device->max_speed = device->node->max_speed;
 445
 446         /*
 447          * Determine the speed of
 448          *   - devices with link speed less than PHY speed,
 449          *   - devices with 1394b PHY (unless only connected to 1394a PHYs),
 450          *   - all devices if there are 1394b repeaters.
 451          * Note, we cannot use the bus info block's link_spd as starting point
 452          * because some buggy firmwares set it lower than necessary and because
 453          * 1394-1995 nodes do not have the field.
 454          */
 455         if ((rom[2] & 0x7) < device->max_speed ||
 456             device->max_speed == SCODE_BETA ||
 457             device->card->beta_repeaters_present) {
 458                 u32 dummy;
 459
 460                 /* for S1600 and S3200 */
 461                 if (device->max_speed == SCODE_BETA)
 462                         device->max_speed = device->card->link_speed;
 463
 464                 while (device->max_speed > SCODE_100) {
 465                         if (read_rom(device, generation, 0, &dummy) ==
 466                             RCODE_COMPLETE)
 467                                 break;
 468                         device->max_speed--;
 469                 }
 470         }
 471
 472         /*
 473          * Now parse the config rom.  The config rom is a recursive
 474          * directory structure so we parse it using a stack of
 475          * references to the blocks that make up the structure.  We
 476          * push a reference to the root directory on the stack to
 477          * start things off.
 478          */
 479         length = i;
 480         sp = 0;
 481         stack[sp++] = 0xc0000005;
 482         while (sp > 0) {
 483                 /*
 484                  * Pop the next block reference of the stack.  The
 485                  * lower 24 bits is the offset into the config rom,
 486                  * the upper 8 bits are the type of the reference the
 487                  * block.
 488                  */
 489                 key = stack[--sp];
 490                 i = key & 0xffffff;
 491                 if (i >= READ_BIB_ROM_SIZE)
 492                         /*
 493                          * The reference points outside the standard
 494                          * config rom area, something's fishy.
 495                          */
 496                         goto out;
 497
 498                 /* Read header quadlet for the block to get the length. */
 499                 if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
 500                         goto out;
 501                 end = i + (rom[i] >> 16) + 1;
 502                 i++;
 503                 if (end > READ_BIB_ROM_SIZE)
 504                         /*
 505                          * This block extends outside standard config
 506                          * area (and the array we're reading it
 507                          * into).  That's broken, so ignore this
 508                          * device.
 509                          */
 510                         goto out;
 511
 512                 /*
 513                  * Now read in the block.  If this is a directory
 514                  * block, check the entries as we read them to see if
 515                  * it references another block, and push it in that case.
 516                  */
 517                 while (i < end) {
 518                         if (read_rom(device, generation, i, &rom[i]) !=
 519                             RCODE_COMPLETE)
 520                                 goto out;
 521                         if ((key >> 30) == 3 && (rom[i] >> 30) > 1 &&
 522                             sp < READ_BIB_STACK_SIZE)
 523                                 stack[sp++] = i + rom[i];
 524                         i++;
 525                 }
 526                 if (length < i)
 527                         length = i;
 528         }
 529
 530         old_rom = device->config_rom;
 531         new_rom = kmemdup(rom, length * 4, GFP_KERNEL);
 532         if (new_rom == NULL)
 533                 goto out;
 534
 535         down_write(&fw_device_rwsem);
 536         device->config_rom = new_rom;
 537         device->config_rom_length = length;
 538         up_write(&fw_device_rwsem);
 539
 540         kfree(old_rom);
 541         ret = 0;
 542         device->cmc = rom[2] & 1 << 30;
 543  out:
 544         kfree(rom);
 545
 546         return ret;
 547 }
 548
 549 static void fw_unit_release(struct device *dev)
 550 {
 551         struct fw_unit *unit = fw_unit(dev);
 552
 553         kfree(unit);
 554 }
 555
 556 static struct device_type fw_unit_type = {
 557         .uevent         = fw_unit_uevent,
 558         .release        = fw_unit_release,
 559 };
 560
 561 static int is_fw_unit(struct device *dev)
 562 {
 563         return dev->type == &fw_unit_type;
 564 }
 565
 566 static void create_units(struct fw_device *device)
 567 {
 568         struct fw_csr_iterator ci;
 569         struct fw_unit *unit;
 570         int key, value, i;
 571
 572         i = 0;
 573         fw_csr_iterator_init(&ci, &device->config_rom[5]);
 574         while (fw_csr_iterator_next(&ci, &key, &value)) {
 575                 if (key != (CSR_UNIT | CSR_DIRECTORY))
 576                         continue;
 577
 578                 /*
 579                  * Get the address of the unit directory and try to
 580                  * match the drivers id_tables against it.
 581                  */
 582                 unit = kzalloc(sizeof(*unit), GFP_KERNEL);
 583                 if (unit == NULL) {
 584                         fw_error("failed to allocate memory for unit\n");
 585                         continue;
 586                 }
 587
 588                 unit->directory = ci.p + value - 1;
 589                 unit->device.bus = &fw_bus_type;
 590                 unit->device.type = &fw_unit_type;
 591                 unit->device.parent = &device->device;
 592                 dev_set_name(&unit->device, "%s.%d", dev_name(&device->device), i++);
 593
 594                 init_fw_attribute_group(&unit->device,
 595                                         fw_unit_attributes,
 596                                         &unit->attribute_group);
 597                 if (device_register(&unit->device) < 0)
 598                         goto skip_unit;
 599
 600                 continue;
 601
 602         skip_unit:
 603                 kfree(unit);
 604         }
 605 }
 606
 607 static int shutdown_unit(struct device *device, void *data)
 608 {
 609         device_unregister(device);
 610
 611         return 0;
 612 }
 613
 614 /*
 615  * fw_device_rwsem acts as dual purpose mutex:
 616  *   - serializes accesses to fw_device_idr,
 617  *   - serializes accesses to fw_device.config_rom/.config_rom_length and
 618  *     fw_unit.directory, unless those accesses happen at safe occasions
 619  */
 620 DECLARE_RWSEM(fw_device_rwsem);
 621
 622 DEFINE_IDR(fw_device_idr);
 623 int fw_cdev_major;
 624
 625 struct fw_device *fw_device_get_by_devt(dev_t devt)
 626 {
 627         struct fw_device *device;
 628
 629         down_read(&fw_device_rwsem);
 630         device = idr_find(&fw_device_idr, MINOR(devt));
 631         if (device)
 632                 fw_device_get(device);
 633         up_read(&fw_device_rwsem);
 634
 635         return device;
 636 }
 637
 638 /*
 639  * These defines control the retry behavior for reading the config
 640  * rom.  It shouldn't be necessary to tweak these; if the device
 641  * doesn't respond to a config rom read within 10 seconds, it's not
 642  * going to respond at all.  As for the initial delay, a lot of
 643  * devices will be able to respond within half a second after bus
 644  * reset.  On the other hand, it's not really worth being more
 645  * aggressive than that, since it scales pretty well; if 10 devices
 646  * are plugged in, they're all getting read within one second.
 647  */
 648
 649 #define MAX_RETRIES     10
 650 #define RETRY_DELAY     (3 * HZ)
 651 #define INITIAL_DELAY   (HZ / 2)
 652 #define SHUTDOWN_DELAY  (2 * HZ)
 653
 654 static void fw_device_shutdown(struct work_struct *work)
 655 {
 656         struct fw_device *device =
 657                 container_of(work, struct fw_device, work.work);
 658         int minor = MINOR(device->device.devt);
 659
 660         if (time_is_after_jiffies(device->card->reset_jiffies + SHUTDOWN_DELAY)
 661             && !list_empty(&device->card->link)) {
 662                 schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
 663                 return;
 664         }
 665
 666         if (atomic_cmpxchg(&device->state,
 667                            FW_DEVICE_GONE,
 668                            FW_DEVICE_SHUTDOWN) != FW_DEVICE_GONE)
 669                 return;
 670
 671         fw_device_cdev_remove(device);
 672         device_for_each_child(&device->device, NULL, shutdown_unit);
 673         device_unregister(&device->device);
 674
 675         down_write(&fw_device_rwsem);
 676         idr_remove(&fw_device_idr, minor);
 677         up_write(&fw_device_rwsem);
 678
 679         fw_device_put(device);
 680 }
 681
 682 static struct device_type fw_device_type = {
 683         .release        = fw_device_release,
 684 };
 685
 686 static void fw_device_update(struct work_struct *work);
 687
 688 /*
 689  * If a device was pending for deletion because its node went away but its
 690  * bus info block and root directory header matches that of a newly discovered
 691  * device, revive the existing fw_device.
 692  * The newly allocated fw_device becomes obsolete instead.
 693  */
 694 static int lookup_existing_device(struct device *dev, void *data)
 695 {
 696         struct fw_device *old = fw_device(dev);
 697         struct fw_device *new = data;
 698         struct fw_card *card = new->card;
 699         int match = 0;
 700
 701         down_read(&fw_device_rwsem); /* serialize config_rom access */
 702         spin_lock_irq(&card->lock);  /* serialize node access */
 703
 704         if (memcmp(old->config_rom, new->config_rom, 6 * 4) == 0 &&
 705             atomic_cmpxchg(&old->state,
 706                            FW_DEVICE_GONE,
 707                            FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
 708                 struct fw_node *current_node = new->node;
 709                 struct fw_node *obsolete_node = old->node;
 710
 711                 new->node = obsolete_node;
 712                 new->node->data = new;
 713                 old->node = current_node;
 714                 old->node->data = old;
 715
 716                 old->max_speed = new->max_speed;
 717                 old->node_id = current_node->node_id;
 718                 smp_wmb();  /* update node_id before generation */
 719                 old->generation = card->generation;
 720                 old->config_rom_retries = 0;
 721                 fw_notify("rediscovered device %s\n", dev_name(dev));
 722
 723                 PREPARE_DELAYED_WORK(&old->work, fw_device_update);
 724                 schedule_delayed_work(&old->work, 0);
 725
 726                 if (current_node == card->root_node)
 727                         fw_schedule_bm_work(card, 0);
 728
 729                 match = 1;
 730         }
 731
 732         spin_unlock_irq(&card->lock);
 733         up_read(&fw_device_rwsem);
 734
 735         return match;
 736 }
 737
 738 static void fw_device_init(struct work_struct *work)
 739 {
 740         struct fw_device *device =
 741                 container_of(work, struct fw_device, work.work);
 742         struct device *revived_dev;
 743         int minor, err;
 744
 745         /*
 746          * All failure paths here set node->data to NULL, so that we
 747          * don't try to do device_for_each_child() on a kfree()'d
 748          * device.
 749          */
 750
 751         if (read_bus_info_block(device, device->generation) < 0) {
 752                 if (device->config_rom_retries < MAX_RETRIES &&
 753                     atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
 754                         device->config_rom_retries++;
 755                         schedule_delayed_work(&device->work, RETRY_DELAY);
 756                 } else {
 757                         fw_notify("giving up on config rom for node id %x\n",
 758                                   device->node_id);
 759                         if (device->node == device->card->root_node)
 760                                 fw_schedule_bm_work(device->card, 0);
 761                         fw_device_release(&device->device);
 762                 }
 763                 return;
 764         }
 765
 766         revived_dev = device_find_child(device->card->device,
 767                                         device, lookup_existing_device);
 768         if (revived_dev) {
 769                 put_device(revived_dev);
 770                 fw_device_release(&device->device);
 771
 772                 return;
 773         }
 774
 775         device_initialize(&device->device);
 776
 777         fw_device_get(device);
 778         down_write(&fw_device_rwsem);
 779         err = idr_pre_get(&fw_device_idr, GFP_KERNEL) ?
 780               idr_get_new(&fw_device_idr, device, &minor) :
 781               -ENOMEM;
 782         up_write(&fw_device_rwsem);
 783
 784         if (err < 0)
 785                 goto error;
 786
 787         device->device.bus = &fw_bus_type;
 788         device->device.type = &fw_device_type;
 789         device->device.parent = device->card->device;
 790         device->device.devt = MKDEV(fw_cdev_major, minor);
 791         dev_set_name(&device->device, "fw%d", minor);
 792
 793         init_fw_attribute_group(&device->device,
 794                                 fw_device_attributes,
 795                                 &device->attribute_group);
 796         if (device_add(&device->device)) {
 797                 fw_error("Failed to add device.\n");
 798                 goto error_with_cdev;
 799         }
 800
 801         create_units(device);
 802
 803         /*
 804          * Transition the device to running state.  If it got pulled
 805          * out from under us while we did the intialization work, we
 806          * have to shut down the device again here.  Normally, though,
 807          * fw_node_event will be responsible for shutting it down when
 808          * necessary.  We have to use the atomic cmpxchg here to avoid
 809          * racing with the FW_NODE_DESTROYED case in
 810          * fw_node_event().
 811          */
 812         if (atomic_cmpxchg(&device->state,
 813                            FW_DEVICE_INITIALIZING,
 814                            FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
 815                 PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
 816                 schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
 817         } else {
 818                 if (device->config_rom_retries)
 819                         fw_notify("created device %s: GUID %08x%08x, S%d00, "
 820                                   "%d config ROM retries\n",
 821                                   dev_name(&device->device),
 822                                   device->config_rom[3], device->config_rom[4],
 823                                   1 << device->max_speed,
 824                                   device->config_rom_retries);
 825                 else
 826                         fw_notify("created device %s: GUID %08x%08x, S%d00\n",
 827                                   dev_name(&device->device),
 828                                   device->config_rom[3], device->config_rom[4],
 829                                   1 << device->max_speed);
 830                 device->config_rom_retries = 0;
 831         }
 832
 833         /*
 834          * Reschedule the IRM work if we just finished reading the
 835          * root node config rom.  If this races with a bus reset we
 836          * just end up running the IRM work a couple of extra times -
 837          * pretty harmless.
 838          */
 839         if (device->node == device->card->root_node)
 840                 fw_schedule_bm_work(device->card, 0);
 841
 842         return;
 843
 844  error_with_cdev:
 845         down_write(&fw_device_rwsem);
 846         idr_remove(&fw_device_idr, minor);
 847         up_write(&fw_device_rwsem);
 848  error:
 849         fw_device_put(device);          /* fw_device_idr's reference */
 850
 851         put_device(&device->device);    /* our reference */
 852 }
 853
 854 static int update_unit(struct device *dev, void *data)
 855 {
 856         struct fw_unit *unit = fw_unit(dev);
 857         struct fw_driver *driver = (struct fw_driver *)dev->driver;
 858
 859         if (is_fw_unit(dev) && driver != NULL && driver->update != NULL) {
 860                 down(&dev->sem);
 861                 driver->update(unit);
 862                 up(&dev->sem);
 863         }
 864
 865         return 0;
 866 }
 867
 868 static void fw_device_update(struct work_struct *work)
 869 {
 870         struct fw_device *device =
 871                 container_of(work, struct fw_device, work.work);
 872
 873         fw_device_cdev_update(device);
 874         device_for_each_child(&device->device, NULL, update_unit);
 875 }
 876
 877 enum {
 878         REREAD_BIB_ERROR,
 879         REREAD_BIB_GONE,
 880         REREAD_BIB_UNCHANGED,
 881         REREAD_BIB_CHANGED,
 882 };
 883
 884 /* Reread and compare bus info block and header of root directory */
 885 static int reread_bus_info_block(struct fw_device *device, int generation)
 886 {
 887         u32 q;
 888         int i;
 889
 890         for (i = 0; i < 6; i++) {
 891                 if (read_rom(device, generation, i, &q) != RCODE_COMPLETE)
 892                         return REREAD_BIB_ERROR;
 893
 894                 if (i == 0 && q == 0)
 895                         return REREAD_BIB_GONE;
 896
 897                 if (i > device->config_rom_length || q != device->config_rom[i])
 898                         return REREAD_BIB_CHANGED;
 899         }
 900
 901         return REREAD_BIB_UNCHANGED;
 902 }
 903
 904 static void fw_device_refresh(struct work_struct *work)
 905 {
 906         struct fw_device *device =
 907                 container_of(work, struct fw_device, work.work);
 908         struct fw_card *card = device->card;
 909         int node_id = device->node_id;
 910
 911         switch (reread_bus_info_block(device, device->generation)) {
 912         case REREAD_BIB_ERROR:
 913                 if (device->config_rom_retries < MAX_RETRIES / 2 &&
 914                     atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
 915                         device->config_rom_retries++;
 916                         schedule_delayed_work(&device->work, RETRY_DELAY / 2);
 917
 918                         return;
 919                 }
 920                 goto give_up;
 921
 922         case REREAD_BIB_GONE:
 923                 goto gone;
 924
 925         case REREAD_BIB_UNCHANGED:
 926                 if (atomic_cmpxchg(&device->state,
 927                                    FW_DEVICE_INITIALIZING,
 928                                    FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
 929                         goto gone;
 930
 931                 fw_device_update(work);
 932                 device->config_rom_retries = 0;
 933                 goto out;
 934
 935         case REREAD_BIB_CHANGED:
 936                 break;
 937         }
 938
 939         /*
 940          * Something changed.  We keep things simple and don't investigate
 941          * further.  We just destroy all previous units and create new ones.
 942          */
 943         device_for_each_child(&device->device, NULL, shutdown_unit);
 944
 945         if (read_bus_info_block(device, device->generation) < 0) {
 946                 if (device->config_rom_retries < MAX_RETRIES &&
 947                     atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
 948                         device->config_rom_retries++;
 949                         schedule_delayed_work(&device->work, RETRY_DELAY);
 950
 951                         return;
 952                 }
 953                 goto give_up;
 954         }
 955
 956         create_units(device);
 957
 958         if (atomic_cmpxchg(&device->state,
 959                            FW_DEVICE_INITIALIZING,
 960                            FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
 961                 goto gone;
 962
 963         fw_notify("refreshed device %s\n", dev_name(&device->device));
 964         device->config_rom_retries = 0;
 965         goto out;
 966
 967  give_up:
 968         fw_notify("giving up on refresh of device %s\n", dev_name(&device->device));
 969  gone:
 970         atomic_set(&device->state, FW_DEVICE_GONE);
 971         PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
 972         schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
 973  out:
 974         if (node_id == card->root_node->node_id)
 975                 fw_schedule_bm_work(card, 0);
 976 }
 977
 978 void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 979 {
 980         struct fw_device *device;
 981
 982         switch (event) {
 983         case FW_NODE_CREATED:
 984         case FW_NODE_LINK_ON:
 985                 if (!node->link_on)
 986                         break;
 987  create:
 988                 device = kzalloc(sizeof(*device), GFP_ATOMIC);
 989                 if (device == NULL)
 990                         break;
 991
 992                 /*
 993                  * Do minimal intialization of the device here, the
 994                  * rest will happen in fw_device_init().
 995                  *
 996                  * Attention:  A lot of things, even fw_device_get(),
 997                  * cannot be done before fw_device_init() finished!
 998                  * You can basically just check device->state and
 999                  * schedule work until then, but only while holding
1000                  * card->lock.
1001                  */
1002                 atomic_set(&device->state, FW_DEVICE_INITIALIZING);
1003                 device->card = fw_card_get(card);
1004                 device->node = fw_node_get(node);
1005                 device->node_id = node->node_id;
1006                 device->generation = card->generation;
1007                 INIT_LIST_HEAD(&device->client_list);
1008
1009                 /*
1010                  * Set the node data to point back to this device so
1011                  * FW_NODE_UPDATED callbacks can update the node_id
1012                  * and generation for the device.
1013                  */
1014                 node->data = device;
1015
1016                 /*
1017                  * Many devices are slow to respond after bus resets,
1018                  * especially if they are bus powered and go through
1019                  * power-up after getting plugged in.  We schedule the
1020                  * first config rom scan half a second after bus reset.
1021                  */
1022                 INIT_DELAYED_WORK(&device->work, fw_device_init);
1023                 schedule_delayed_work(&device->work, INITIAL_DELAY);
1024                 break;
1025
1026         case FW_NODE_INITIATED_RESET:
1027                 device = node->data;
1028                 if (device == NULL)
1029                         goto create;
1030
1031                 device->node_id = node->node_id;
1032                 smp_wmb();  /* update node_id before generation */
1033                 device->generation = card->generation;
1034                 if (atomic_cmpxchg(&device->state,
1035                             FW_DEVICE_RUNNING,
1036                             FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) {
1037                         PREPARE_DELAYED_WORK(&device->work, fw_device_refresh);
1038                         schedule_delayed_work(&device->work,
1039                                 node == card->local_node ? 0 : INITIAL_DELAY);
1040                 }
1041                 break;
1042
1043         case FW_NODE_UPDATED:
1044                 if (!node->link_on || node->data == NULL)
1045                         break;
1046
1047                 device = node->data;
1048                 device->node_id = node->node_id;
1049                 smp_wmb();  /* update node_id before generation */
1050                 device->generation = card->generation;
1051                 if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
1052                         PREPARE_DELAYED_WORK(&device->work, fw_device_update);
1053                         schedule_delayed_work(&device->work, 0);
1054                 }
1055                 break;
1056
1057         case FW_NODE_DESTROYED:
1058         case FW_NODE_LINK_OFF:
1059                 if (!node->data)
1060                         break;
1061
1062                 /*
1063                  * Destroy the device associated with the node.  There
1064                  * are two cases here: either the device is fully
1065                  * initialized (FW_DEVICE_RUNNING) or we're in the
1066                  * process of reading its config rom
1067                  * (FW_DEVICE_INITIALIZING).  If it is fully
1068                  * initialized we can reuse device->work to schedule a
1069                  * full fw_device_shutdown().  If not, there's work
1070                  * scheduled to read it's config rom, and we just put
1071                  * the device in shutdown state to have that code fail
1072                  * to create the device.
1073                  */
1074                 device = node->data;
1075                 if (atomic_xchg(&device->state,
1076                                 FW_DEVICE_GONE) == FW_DEVICE_RUNNING) {
1077                         PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
1078                         schedule_delayed_work(&device->work,
1079                                 list_empty(&card->link) ? 0 : SHUTDOWN_DELAY);
1080                 }
1081                 break;
1082         }
1083 }