git.oblomov.eu Git - linux-2.6/blob - drivers/acpi/scan.c

   1 /*
   2  * scan.c - support for transforming the ACPI namespace into individual objects
   3  */
   4
   5 #include <linux/module.h>
   6 #include <linux/init.h>
   7 #include <linux/acpi.h>
   8
   9 #include <acpi/acpi_drivers.h>
  10 #include <acpi/acinterp.h>      /* for acpi_ex_eisa_id_to_string() */
  11
  12 #define _COMPONENT              ACPI_BUS_COMPONENT
  13 ACPI_MODULE_NAME("scan")
  14 #define STRUCT_TO_INT(s)        (*((int*)&s))
  15 extern struct acpi_device *acpi_root;
  16
  17 #define ACPI_BUS_CLASS                  "system_bus"
  18 #define ACPI_BUS_HID                    "ACPI_BUS"
  19 #define ACPI_BUS_DRIVER_NAME            "ACPI Bus Driver"
  20 #define ACPI_BUS_DEVICE_NAME            "System Bus"
  21
  22 static LIST_HEAD(acpi_device_list);
  23 DEFINE_SPINLOCK(acpi_device_lock);
  24 LIST_HEAD(acpi_wakeup_device_list);
  25
  26
  27 static void acpi_device_release(struct kobject *kobj)
  28 {
  29         struct acpi_device *dev = container_of(kobj, struct acpi_device, kobj);
  30         kfree(dev->pnp.cid_list);
  31         kfree(dev);
  32 }
  33
  34 struct acpi_device_attribute {
  35         struct attribute attr;
  36          ssize_t(*show) (struct acpi_device *, char *);
  37          ssize_t(*store) (struct acpi_device *, const char *, size_t);
  38 };
  39
  40 typedef void acpi_device_sysfs_files(struct kobject *,
  41                                      const struct attribute *);
  42
  43 static void setup_sys_fs_device_files(struct acpi_device *dev,
  44                                       acpi_device_sysfs_files * func);
  45
  46 #define create_sysfs_device_files(dev)  \
  47         setup_sys_fs_device_files(dev, (acpi_device_sysfs_files *)&sysfs_create_file)
  48 #define remove_sysfs_device_files(dev)  \
  49         setup_sys_fs_device_files(dev, (acpi_device_sysfs_files *)&sysfs_remove_file)
  50
  51 #define to_acpi_device(n) container_of(n, struct acpi_device, kobj)
  52 #define to_handle_attr(n) container_of(n, struct acpi_device_attribute, attr);
  53
  54 static ssize_t acpi_device_attr_show(struct kobject *kobj,
  55                                      struct attribute *attr, char *buf)
  56 {
  57         struct acpi_device *device = to_acpi_device(kobj);
  58         struct acpi_device_attribute *attribute = to_handle_attr(attr);
  59         return attribute->show ? attribute->show(device, buf) : -EIO;
  60 }
  61 static ssize_t acpi_device_attr_store(struct kobject *kobj,
  62                                       struct attribute *attr, const char *buf,
  63                                       size_t len)
  64 {
  65         struct acpi_device *device = to_acpi_device(kobj);
  66         struct acpi_device_attribute *attribute = to_handle_attr(attr);
  67         return attribute->store ? attribute->store(device, buf, len) : -EIO;
  68 }
  69
  70 static struct sysfs_ops acpi_device_sysfs_ops = {
  71         .show = acpi_device_attr_show,
  72         .store = acpi_device_attr_store,
  73 };
  74
  75 static struct kobj_type ktype_acpi_ns = {
  76         .sysfs_ops = &acpi_device_sysfs_ops,
  77         .release = acpi_device_release,
  78 };
  79
  80 static int namespace_uevent(struct kset *kset, struct kobject *kobj,
  81                              char **envp, int num_envp, char *buffer,
  82                              int buffer_size)
  83 {
  84         struct acpi_device *dev = to_acpi_device(kobj);
  85         int i = 0;
  86         int len = 0;
  87
  88         if (!dev->driver)
  89                 return 0;
  90
  91         if (add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &len,
  92                            "PHYSDEVDRIVER=%s", dev->driver->name))
  93                 return -ENOMEM;
  94
  95         envp[i] = NULL;
  96
  97         return 0;
  98 }
  99
 100 static struct kset_uevent_ops namespace_uevent_ops = {
 101         .uevent = &namespace_uevent,
 102 };
 103
 104 static struct kset acpi_namespace_kset = {
 105         .kobj = {
 106                  .name = "namespace",
 107                  },
 108         .subsys = &acpi_subsys,
 109         .ktype = &ktype_acpi_ns,
 110         .uevent_ops = &namespace_uevent_ops,
 111 };
 112
 113 static void acpi_device_register(struct acpi_device *device,
 114                                  struct acpi_device *parent)
 115 {
 116         /*
 117          * Linkage
 118          * -------
 119          * Link this device to its parent and siblings.
 120          */
 121         INIT_LIST_HEAD(&device->children);
 122         INIT_LIST_HEAD(&device->node);
 123         INIT_LIST_HEAD(&device->g_list);
 124         INIT_LIST_HEAD(&device->wakeup_list);
 125
 126         spin_lock(&acpi_device_lock);
 127         if (device->parent) {
 128                 list_add_tail(&device->node, &device->parent->children);
 129                 list_add_tail(&device->g_list, &device->parent->g_list);
 130         } else
 131                 list_add_tail(&device->g_list, &acpi_device_list);
 132         if (device->wakeup.flags.valid)
 133                 list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);
 134         spin_unlock(&acpi_device_lock);
 135
 136         strlcpy(device->kobj.name, device->pnp.bus_id, KOBJ_NAME_LEN);
 137         if (parent)
 138                 device->kobj.parent = &parent->kobj;
 139         device->kobj.ktype = &ktype_acpi_ns;
 140         device->kobj.kset = &acpi_namespace_kset;
 141         kobject_register(&device->kobj);
 142         create_sysfs_device_files(device);
 143 }
 144
 145 static int acpi_device_unregister(struct acpi_device *device, int type)
 146 {
 147         spin_lock(&acpi_device_lock);
 148         if (device->parent) {
 149                 list_del(&device->node);
 150                 list_del(&device->g_list);
 151         } else
 152                 list_del(&device->g_list);
 153
 154         list_del(&device->wakeup_list);
 155
 156         spin_unlock(&acpi_device_lock);
 157
 158         acpi_detach_data(device->handle, acpi_bus_data_handler);
 159         remove_sysfs_device_files(device);
 160         kobject_unregister(&device->kobj);
 161         return 0;
 162 }
 163
 164 void acpi_bus_data_handler(acpi_handle handle, u32 function, void *context)
 165 {
 166         ACPI_FUNCTION_TRACE("acpi_bus_data_handler");
 167
 168         /* TBD */
 169
 170         return_VOID;
 171 }
 172
 173 static int acpi_bus_get_power_flags(struct acpi_device *device)
 174 {
 175         acpi_status status = 0;
 176         acpi_handle handle = NULL;
 177         u32 i = 0;
 178
 179         ACPI_FUNCTION_TRACE("acpi_bus_get_power_flags");
 180
 181         /*
 182          * Power Management Flags
 183          */
 184         status = acpi_get_handle(device->handle, "_PSC", &handle);
 185         if (ACPI_SUCCESS(status))
 186                 device->power.flags.explicit_get = 1;
 187         status = acpi_get_handle(device->handle, "_IRC", &handle);
 188         if (ACPI_SUCCESS(status))
 189                 device->power.flags.inrush_current = 1;
 190
 191         /*
 192          * Enumerate supported power management states
 193          */
 194         for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3; i++) {
 195                 struct acpi_device_power_state *ps = &device->power.states[i];
 196                 char object_name[5] = { '_', 'P', 'R', '0' + i, '\0' };
 197
 198                 /* Evaluate "_PRx" to se if power resources are referenced */
 199                 acpi_evaluate_reference(device->handle, object_name, NULL,
 200                                         &ps->resources);
 201                 if (ps->resources.count) {
 202                         device->power.flags.power_resources = 1;
 203                         ps->flags.valid = 1;
 204                 }
 205
 206                 /* Evaluate "_PSx" to see if we can do explicit sets */
 207                 object_name[2] = 'S';
 208                 status = acpi_get_handle(device->handle, object_name, &handle);
 209                 if (ACPI_SUCCESS(status)) {
 210                         ps->flags.explicit_set = 1;
 211                         ps->flags.valid = 1;
 212                 }
 213
 214                 /* State is valid if we have some power control */
 215                 if (ps->resources.count || ps->flags.explicit_set)
 216                         ps->flags.valid = 1;
 217
 218                 ps->power = -1; /* Unknown - driver assigned */
 219                 ps->latency = -1;       /* Unknown - driver assigned */
 220         }
 221
 222         /* Set defaults for D0 and D3 states (always valid) */
 223         device->power.states[ACPI_STATE_D0].flags.valid = 1;
 224         device->power.states[ACPI_STATE_D0].power = 100;
 225         device->power.states[ACPI_STATE_D3].flags.valid = 1;
 226         device->power.states[ACPI_STATE_D3].power = 0;
 227
 228         /* TBD: System wake support and resource requirements. */
 229
 230         device->power.state = ACPI_STATE_UNKNOWN;
 231
 232         return_VALUE(0);
 233 }
 234
 235 int acpi_match_ids(struct acpi_device *device, char *ids)
 236 {
 237         if (device->flags.hardware_id)
 238                 if (strstr(ids, device->pnp.hardware_id))
 239                         return 0;
 240
 241         if (device->flags.compatible_ids) {
 242                 struct acpi_compatible_id_list *cid_list = device->pnp.cid_list;
 243                 int i;
 244
 245                 /* compare multiple _CID entries against driver ids */
 246                 for (i = 0; i < cid_list->count; i++) {
 247                         if (strstr(ids, cid_list->id[i].value))
 248                                 return 0;
 249                 }
 250         }
 251         return -ENOENT;
 252 }
 253
 254 static acpi_status
 255 acpi_bus_extract_wakeup_device_power_package(struct acpi_device *device,
 256                                              union acpi_object *package)
 257 {
 258         int i = 0;
 259         union acpi_object *element = NULL;
 260
 261         if (!device || !package || (package->package.count < 2))
 262                 return AE_BAD_PARAMETER;
 263
 264         element = &(package->package.elements[0]);
 265         if (!element)
 266                 return AE_BAD_PARAMETER;
 267         if (element->type == ACPI_TYPE_PACKAGE) {
 268                 if ((element->package.count < 2) ||
 269                     (element->package.elements[0].type !=
 270                      ACPI_TYPE_LOCAL_REFERENCE)
 271                     || (element->package.elements[1].type != ACPI_TYPE_INTEGER))
 272                         return AE_BAD_DATA;
 273                 device->wakeup.gpe_device =
 274                     element->package.elements[0].reference.handle;
 275                 device->wakeup.gpe_number =
 276                     (u32) element->package.elements[1].integer.value;
 277         } else if (element->type == ACPI_TYPE_INTEGER) {
 278                 device->wakeup.gpe_number = element->integer.value;
 279         } else
 280                 return AE_BAD_DATA;
 281
 282         element = &(package->package.elements[1]);
 283         if (element->type != ACPI_TYPE_INTEGER) {
 284                 return AE_BAD_DATA;
 285         }
 286         device->wakeup.sleep_state = element->integer.value;
 287
 288         if ((package->package.count - 2) > ACPI_MAX_HANDLES) {
 289                 return AE_NO_MEMORY;
 290         }
 291         device->wakeup.resources.count = package->package.count - 2;
 292         for (i = 0; i < device->wakeup.resources.count; i++) {
 293                 element = &(package->package.elements[i + 2]);
 294                 if (element->type != ACPI_TYPE_ANY) {
 295                         return AE_BAD_DATA;
 296                 }
 297
 298                 device->wakeup.resources.handles[i] = element->reference.handle;
 299         }
 300
 301         return AE_OK;
 302 }
 303
 304 static int acpi_bus_get_wakeup_device_flags(struct acpi_device *device)
 305 {
 306         acpi_status status = 0;
 307         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 308         union acpi_object *package = NULL;
 309
 310         ACPI_FUNCTION_TRACE("acpi_bus_get_wakeup_flags");
 311
 312         /* _PRW */
 313         status = acpi_evaluate_object(device->handle, "_PRW", NULL, &buffer);
 314         if (ACPI_FAILURE(status)) {
 315                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error evaluating _PRW\n"));
 316                 goto end;
 317         }
 318
 319         package = (union acpi_object *)buffer.pointer;
 320         status = acpi_bus_extract_wakeup_device_power_package(device, package);
 321         if (ACPI_FAILURE(status)) {
 322                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 323                                   "Error extracting _PRW package\n"));
 324                 goto end;
 325         }
 326
 327         acpi_os_free(buffer.pointer);
 328
 329         device->wakeup.flags.valid = 1;
 330         /* Power button, Lid switch always enable wakeup */
 331         if (!acpi_match_ids(device, "PNP0C0D,PNP0C0C,PNP0C0E"))
 332                 device->wakeup.flags.run_wake = 1;
 333
 334       end:
 335         if (ACPI_FAILURE(status))
 336                 device->flags.wake_capable = 0;
 337         return_VALUE(0);
 338 }
 339
 340 /* --------------------------------------------------------------------------
 341                 ACPI sysfs device file support
 342    -------------------------------------------------------------------------- */
 343 static ssize_t acpi_eject_store(struct acpi_device *device,
 344                                 const char *buf, size_t count);
 345
 346 #define ACPI_DEVICE_ATTR(_name,_mode,_show,_store) \
 347 static struct acpi_device_attribute acpi_device_attr_##_name = \
 348                 __ATTR(_name, _mode, _show, _store)
 349
 350 ACPI_DEVICE_ATTR(eject, 0200, NULL, acpi_eject_store);
 351
 352 /**
 353  * setup_sys_fs_device_files - sets up the device files under device namespace
 354  * @dev:        acpi_device object
 355  * @func:       function pointer to create or destroy the device file
 356  */
 357 static void
 358 setup_sys_fs_device_files(struct acpi_device *dev,
 359                           acpi_device_sysfs_files * func)
 360 {
 361         acpi_status status;
 362         acpi_handle temp = NULL;
 363
 364         /*
 365          * If device has _EJ0, 'eject' file is created that is used to trigger
 366          * hot-removal function from userland.
 367          */
 368         status = acpi_get_handle(dev->handle, "_EJ0", &temp);
 369         if (ACPI_SUCCESS(status))
 370                 (*(func)) (&dev->kobj, &acpi_device_attr_eject.attr);
 371 }
 372
 373 static int acpi_eject_operation(acpi_handle handle, int lockable)
 374 {
 375         struct acpi_object_list arg_list;
 376         union acpi_object arg;
 377         acpi_status status = AE_OK;
 378
 379         /*
 380          * TBD: evaluate _PS3?
 381          */
 382
 383         if (lockable) {
 384                 arg_list.count = 1;
 385                 arg_list.pointer = &arg;
 386                 arg.type = ACPI_TYPE_INTEGER;
 387                 arg.integer.value = 0;
 388                 acpi_evaluate_object(handle, "_LCK", &arg_list, NULL);
 389         }
 390
 391         arg_list.count = 1;
 392         arg_list.pointer = &arg;
 393         arg.type = ACPI_TYPE_INTEGER;
 394         arg.integer.value = 1;
 395
 396         /*
 397          * TBD: _EJD support.
 398          */
 399
 400         status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL);
 401         if (ACPI_FAILURE(status)) {
 402                 return (-ENODEV);
 403         }
 404
 405         return (0);
 406 }
 407
 408 static ssize_t
 409 acpi_eject_store(struct acpi_device *device, const char *buf, size_t count)
 410 {
 411         int result;
 412         int ret = count;
 413         int islockable;
 414         acpi_status status;
 415         acpi_handle handle;
 416         acpi_object_type type = 0;
 417
 418         if ((!count) || (buf[0] != '1')) {
 419                 return -EINVAL;
 420         }
 421 #ifndef FORCE_EJECT
 422         if (device->driver == NULL) {
 423                 ret = -ENODEV;
 424                 goto err;
 425         }
 426 #endif
 427         status = acpi_get_type(device->handle, &type);
 428         if (ACPI_FAILURE(status) || (!device->flags.ejectable)) {
 429                 ret = -ENODEV;
 430                 goto err;
 431         }
 432
 433         islockable = device->flags.lockable;
 434         handle = device->handle;
 435
 436         result = acpi_bus_trim(device, 1);
 437
 438         if (!result)
 439                 result = acpi_eject_operation(handle, islockable);
 440
 441         if (result) {
 442                 ret = -EBUSY;
 443         }
 444       err:
 445         return ret;
 446 }
 447
 448 /* --------------------------------------------------------------------------
 449                               Performance Management
 450    -------------------------------------------------------------------------- */
 451
 452 static int acpi_bus_get_perf_flags(struct acpi_device *device)
 453 {
 454         device->performance.state = ACPI_STATE_UNKNOWN;
 455         return 0;
 456 }
 457
 458 /* --------------------------------------------------------------------------
 459                                  Driver Management
 460    -------------------------------------------------------------------------- */
 461
 462 static LIST_HEAD(acpi_bus_drivers);
 463 static DECLARE_MUTEX(acpi_bus_drivers_lock);
 464
 465 /**
 466  * acpi_bus_match - match device IDs to driver's supported IDs
 467  * @device: the device that we are trying to match to a driver
 468  * @driver: driver whose device id table is being checked
 469  *
 470  * Checks the device's hardware (_HID) or compatible (_CID) ids to see if it
 471  * matches the specified driver's criteria.
 472  */
 473 static int
 474 acpi_bus_match(struct acpi_device *device, struct acpi_driver *driver)
 475 {
 476         if (driver && driver->ops.match)
 477                 return driver->ops.match(device, driver);
 478         return acpi_match_ids(device, driver->ids);
 479 }
 480
 481 /**
 482  * acpi_bus_driver_init - add a device to a driver
 483  * @device: the device to add and initialize
 484  * @driver: driver for the device
 485  *
 486  * Used to initialize a device via its device driver.  Called whenever a
 487  * driver is bound to a device.  Invokes the driver's add() and start() ops.
 488  */
 489 static int
 490 acpi_bus_driver_init(struct acpi_device *device, struct acpi_driver *driver)
 491 {
 492         int result = 0;
 493
 494         ACPI_FUNCTION_TRACE("acpi_bus_driver_init");
 495
 496         if (!device || !driver)
 497                 return_VALUE(-EINVAL);
 498
 499         if (!driver->ops.add)
 500                 return_VALUE(-ENOSYS);
 501
 502         result = driver->ops.add(device);
 503         if (result) {
 504                 device->driver = NULL;
 505                 acpi_driver_data(device) = NULL;
 506                 return_VALUE(result);
 507         }
 508
 509         device->driver = driver;
 510
 511         /*
 512          * TBD - Configuration Management: Assign resources to device based
 513          * upon possible configuration and currently allocated resources.
 514          */
 515
 516         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 517                           "Driver successfully bound to device\n"));
 518         return_VALUE(0);
 519 }
 520
 521 static int acpi_start_single_object(struct acpi_device *device)
 522 {
 523         int result = 0;
 524         struct acpi_driver *driver;
 525
 526         ACPI_FUNCTION_TRACE("acpi_start_single_object");
 527
 528         if (!(driver = device->driver))
 529                 return_VALUE(0);
 530
 531         if (driver->ops.start) {
 532                 result = driver->ops.start(device);
 533                 if (result && driver->ops.remove)
 534                         driver->ops.remove(device, ACPI_BUS_REMOVAL_NORMAL);
 535         }
 536
 537         return_VALUE(result);
 538 }
 539
 540 static int acpi_driver_attach(struct acpi_driver *drv)
 541 {
 542         struct list_head *node, *next;
 543         int count = 0;
 544
 545         ACPI_FUNCTION_TRACE("acpi_driver_attach");
 546
 547         spin_lock(&acpi_device_lock);
 548         list_for_each_safe(node, next, &acpi_device_list) {
 549                 struct acpi_device *dev =
 550                     container_of(node, struct acpi_device, g_list);
 551
 552                 if (dev->driver || !dev->status.present)
 553                         continue;
 554                 spin_unlock(&acpi_device_lock);
 555
 556                 if (!acpi_bus_match(dev, drv)) {
 557                         if (!acpi_bus_driver_init(dev, drv)) {
 558                                 acpi_start_single_object(dev);
 559                                 atomic_inc(&drv->references);
 560                                 count++;
 561                                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 562                                                   "Found driver [%s] for device [%s]\n",
 563                                                   drv->name, dev->pnp.bus_id));
 564                         }
 565                 }
 566                 spin_lock(&acpi_device_lock);
 567         }
 568         spin_unlock(&acpi_device_lock);
 569         return_VALUE(count);
 570 }
 571
 572 static int acpi_driver_detach(struct acpi_driver *drv)
 573 {
 574         struct list_head *node, *next;
 575
 576         ACPI_FUNCTION_TRACE("acpi_driver_detach");
 577
 578         spin_lock(&acpi_device_lock);
 579         list_for_each_safe(node, next, &acpi_device_list) {
 580                 struct acpi_device *dev =
 581                     container_of(node, struct acpi_device, g_list);
 582
 583                 if (dev->driver == drv) {
 584                         spin_unlock(&acpi_device_lock);
 585                         if (drv->ops.remove)
 586                                 drv->ops.remove(dev, ACPI_BUS_REMOVAL_NORMAL);
 587                         spin_lock(&acpi_device_lock);
 588                         dev->driver = NULL;
 589                         dev->driver_data = NULL;
 590                         atomic_dec(&drv->references);
 591                 }
 592         }
 593         spin_unlock(&acpi_device_lock);
 594         return_VALUE(0);
 595 }
 596
 597 /**
 598  * acpi_bus_register_driver - register a driver with the ACPI bus
 599  * @driver: driver being registered
 600  *
 601  * Registers a driver with the ACPI bus.  Searches the namespace for all
 602  * devices that match the driver's criteria and binds.  Returns the
 603  * number of devices that were claimed by the driver, or a negative
 604  * error status for failure.
 605  */
 606 int acpi_bus_register_driver(struct acpi_driver *driver)
 607 {
 608         int count;
 609
 610         ACPI_FUNCTION_TRACE("acpi_bus_register_driver");
 611
 612         if (acpi_disabled)
 613                 return_VALUE(-ENODEV);
 614
 615         if (!driver)
 616                 return_VALUE(-EINVAL);
 617
 618         spin_lock(&acpi_device_lock);
 619         list_add_tail(&driver->node, &acpi_bus_drivers);
 620         spin_unlock(&acpi_device_lock);
 621         count = acpi_driver_attach(driver);
 622
 623         return_VALUE(count);
 624 }
 625
 626 EXPORT_SYMBOL(acpi_bus_register_driver);
 627
 628 /**
 629  * acpi_bus_unregister_driver - unregisters a driver with the APIC bus
 630  * @driver: driver to unregister
 631  *
 632  * Unregisters a driver with the ACPI bus.  Searches the namespace for all
 633  * devices that match the driver's criteria and unbinds.
 634  */
 635 int acpi_bus_unregister_driver(struct acpi_driver *driver)
 636 {
 637         ACPI_FUNCTION_TRACE("acpi_bus_unregister_driver");
 638
 639         if (!driver)
 640                 return_VALUE(-EINVAL);
 641
 642         acpi_driver_detach(driver);
 643
 644         if (!atomic_read(&driver->references)) {
 645                 spin_lock(&acpi_device_lock);
 646                 list_del_init(&driver->node);
 647                 spin_unlock(&acpi_device_lock);
 648         }
 649         return_VALUE(0);
 650 }
 651
 652 EXPORT_SYMBOL(acpi_bus_unregister_driver);
 653
 654 /**
 655  * acpi_bus_find_driver - check if there is a driver installed for the device
 656  * @device: device that we are trying to find a supporting driver for
 657  *
 658  * Parses the list of registered drivers looking for a driver applicable for
 659  * the specified device.
 660  */
 661 static int acpi_bus_find_driver(struct acpi_device *device)
 662 {
 663         int result = 0;
 664         struct list_head *node, *next;
 665
 666         ACPI_FUNCTION_TRACE("acpi_bus_find_driver");
 667
 668         spin_lock(&acpi_device_lock);
 669         list_for_each_safe(node, next, &acpi_bus_drivers) {
 670                 struct acpi_driver *driver =
 671                     container_of(node, struct acpi_driver, node);
 672
 673                 atomic_inc(&driver->references);
 674                 spin_unlock(&acpi_device_lock);
 675                 if (!acpi_bus_match(device, driver)) {
 676                         result = acpi_bus_driver_init(device, driver);
 677                         if (!result)
 678                                 goto Done;
 679                 }
 680                 atomic_dec(&driver->references);
 681                 spin_lock(&acpi_device_lock);
 682         }
 683         spin_unlock(&acpi_device_lock);
 684
 685       Done:
 686         return_VALUE(result);
 687 }
 688
 689 /* --------------------------------------------------------------------------
 690                                  Device Enumeration
 691    -------------------------------------------------------------------------- */
 692
 693 static int acpi_bus_get_flags(struct acpi_device *device)
 694 {
 695         acpi_status status = AE_OK;
 696         acpi_handle temp = NULL;
 697
 698         ACPI_FUNCTION_TRACE("acpi_bus_get_flags");
 699
 700         /* Presence of _STA indicates 'dynamic_status' */
 701         status = acpi_get_handle(device->handle, "_STA", &temp);
 702         if (ACPI_SUCCESS(status))
 703                 device->flags.dynamic_status = 1;
 704
 705         /* Presence of _CID indicates 'compatible_ids' */
 706         status = acpi_get_handle(device->handle, "_CID", &temp);
 707         if (ACPI_SUCCESS(status))
 708                 device->flags.compatible_ids = 1;
 709
 710         /* Presence of _RMV indicates 'removable' */
 711         status = acpi_get_handle(device->handle, "_RMV", &temp);
 712         if (ACPI_SUCCESS(status))
 713                 device->flags.removable = 1;
 714
 715         /* Presence of _EJD|_EJ0 indicates 'ejectable' */
 716         status = acpi_get_handle(device->handle, "_EJD", &temp);
 717         if (ACPI_SUCCESS(status))
 718                 device->flags.ejectable = 1;
 719         else {
 720                 status = acpi_get_handle(device->handle, "_EJ0", &temp);
 721                 if (ACPI_SUCCESS(status))
 722                         device->flags.ejectable = 1;
 723         }
 724
 725         /* Presence of _LCK indicates 'lockable' */
 726         status = acpi_get_handle(device->handle, "_LCK", &temp);
 727         if (ACPI_SUCCESS(status))
 728                 device->flags.lockable = 1;
 729
 730         /* Presence of _PS0|_PR0 indicates 'power manageable' */
 731         status = acpi_get_handle(device->handle, "_PS0", &temp);
 732         if (ACPI_FAILURE(status))
 733                 status = acpi_get_handle(device->handle, "_PR0", &temp);
 734         if (ACPI_SUCCESS(status))
 735                 device->flags.power_manageable = 1;
 736
 737         /* Presence of _PRW indicates wake capable */
 738         status = acpi_get_handle(device->handle, "_PRW", &temp);
 739         if (ACPI_SUCCESS(status))
 740                 device->flags.wake_capable = 1;
 741
 742         /* TBD: Peformance management */
 743
 744         return_VALUE(0);
 745 }
 746
 747 static void acpi_device_get_busid(struct acpi_device *device,
 748                                   acpi_handle handle, int type)
 749 {
 750         char bus_id[5] = { '?', 0 };
 751         struct acpi_buffer buffer = { sizeof(bus_id), bus_id };
 752         int i = 0;
 753
 754         /*
 755          * Bus ID
 756          * ------
 757          * The device's Bus ID is simply the object name.
 758          * TBD: Shouldn't this value be unique (within the ACPI namespace)?
 759          */
 760         switch (type) {
 761         case ACPI_BUS_TYPE_SYSTEM:
 762                 strcpy(device->pnp.bus_id, "ACPI");
 763                 break;
 764         case ACPI_BUS_TYPE_POWER_BUTTON:
 765                 strcpy(device->pnp.bus_id, "PWRF");
 766                 break;
 767         case ACPI_BUS_TYPE_SLEEP_BUTTON:
 768                 strcpy(device->pnp.bus_id, "SLPF");
 769                 break;
 770         default:
 771                 acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
 772                 /* Clean up trailing underscores (if any) */
 773                 for (i = 3; i > 1; i--) {
 774                         if (bus_id[i] == '_')
 775                                 bus_id[i] = '\0';
 776                         else
 777                                 break;
 778                 }
 779                 strcpy(device->pnp.bus_id, bus_id);
 780                 break;
 781         }
 782 }
 783
 784 static void acpi_device_set_id(struct acpi_device *device,
 785                                struct acpi_device *parent, acpi_handle handle,
 786                                int type)
 787 {
 788         struct acpi_device_info *info;
 789         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 790         char *hid = NULL;
 791         char *uid = NULL;
 792         struct acpi_compatible_id_list *cid_list = NULL;
 793         acpi_status status;
 794
 795         switch (type) {
 796         case ACPI_BUS_TYPE_DEVICE:
 797                 status = acpi_get_object_info(handle, &buffer);
 798                 if (ACPI_FAILURE(status)) {
 799                         printk("%s: Error reading device info\n", __FUNCTION__);
 800                         return;
 801                 }
 802
 803                 info = buffer.pointer;
 804                 if (info->valid & ACPI_VALID_HID)
 805                         hid = info->hardware_id.value;
 806                 if (info->valid & ACPI_VALID_UID)
 807                         uid = info->unique_id.value;
 808                 if (info->valid & ACPI_VALID_CID)
 809                         cid_list = &info->compatibility_id;
 810                 if (info->valid & ACPI_VALID_ADR) {
 811                         device->pnp.bus_address = info->address;
 812                         device->flags.bus_address = 1;
 813                 }
 814                 break;
 815         case ACPI_BUS_TYPE_POWER:
 816                 hid = ACPI_POWER_HID;
 817                 break;
 818         case ACPI_BUS_TYPE_PROCESSOR:
 819                 hid = ACPI_PROCESSOR_HID;
 820                 break;
 821         case ACPI_BUS_TYPE_SYSTEM:
 822                 hid = ACPI_SYSTEM_HID;
 823                 break;
 824         case ACPI_BUS_TYPE_THERMAL:
 825                 hid = ACPI_THERMAL_HID;
 826                 break;
 827         case ACPI_BUS_TYPE_POWER_BUTTON:
 828                 hid = ACPI_BUTTON_HID_POWERF;
 829                 break;
 830         case ACPI_BUS_TYPE_SLEEP_BUTTON:
 831                 hid = ACPI_BUTTON_HID_SLEEPF;
 832                 break;
 833         }
 834
 835         /*
 836          * \_SB
 837          * ----
 838          * Fix for the system root bus device -- the only root-level device.
 839          */
 840         if (((acpi_handle)parent == ACPI_ROOT_OBJECT) && (type == ACPI_BUS_TYPE_DEVICE)) {
 841                 hid = ACPI_BUS_HID;
 842                 strcpy(device->pnp.device_name, ACPI_BUS_DEVICE_NAME);
 843                 strcpy(device->pnp.device_class, ACPI_BUS_CLASS);
 844         }
 845
 846         if (hid) {
 847                 strcpy(device->pnp.hardware_id, hid);
 848                 device->flags.hardware_id = 1;
 849         }
 850         if (uid) {
 851                 strcpy(device->pnp.unique_id, uid);
 852                 device->flags.unique_id = 1;
 853         }
 854         if (cid_list) {
 855                 device->pnp.cid_list = kmalloc(cid_list->size, GFP_KERNEL);
 856                 if (device->pnp.cid_list)
 857                         memcpy(device->pnp.cid_list, cid_list, cid_list->size);
 858                 else
 859                         printk(KERN_ERR "Memory allocation error\n");
 860         }
 861
 862         acpi_os_free(buffer.pointer);
 863 }
 864
 865 static int acpi_device_set_context(struct acpi_device *device, int type)
 866 {
 867         acpi_status status = AE_OK;
 868         int result = 0;
 869         /*
 870          * Context
 871          * -------
 872          * Attach this 'struct acpi_device' to the ACPI object.  This makes
 873          * resolutions from handle->device very efficient.  Note that we need
 874          * to be careful with fixed-feature devices as they all attach to the
 875          * root object.
 876          */
 877         if (type != ACPI_BUS_TYPE_POWER_BUTTON &&
 878             type != ACPI_BUS_TYPE_SLEEP_BUTTON) {
 879                 status = acpi_attach_data(device->handle,
 880                                           acpi_bus_data_handler, device);
 881
 882                 if (ACPI_FAILURE(status)) {
 883                         printk("Error attaching device data\n");
 884                         result = -ENODEV;
 885                 }
 886         }
 887         return result;
 888 }
 889
 890 static void acpi_device_get_debug_info(struct acpi_device *device,
 891                                        acpi_handle handle, int type)
 892 {
 893 #ifdef CONFIG_ACPI_DEBUG_OUTPUT
 894         char *type_string = NULL;
 895         char name[80] = { '?', '\0' };
 896         struct acpi_buffer buffer = { sizeof(name), name };
 897
 898         switch (type) {
 899         case ACPI_BUS_TYPE_DEVICE:
 900                 type_string = "Device";
 901                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 902                 break;
 903         case ACPI_BUS_TYPE_POWER:
 904                 type_string = "Power Resource";
 905                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 906                 break;
 907         case ACPI_BUS_TYPE_PROCESSOR:
 908                 type_string = "Processor";
 909                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 910                 break;
 911         case ACPI_BUS_TYPE_SYSTEM:
 912                 type_string = "System";
 913                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 914                 break;
 915         case ACPI_BUS_TYPE_THERMAL:
 916                 type_string = "Thermal Zone";
 917                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 918                 break;
 919         case ACPI_BUS_TYPE_POWER_BUTTON:
 920                 type_string = "Power Button";
 921                 sprintf(name, "PWRB");
 922                 break;
 923         case ACPI_BUS_TYPE_SLEEP_BUTTON:
 924                 type_string = "Sleep Button";
 925                 sprintf(name, "SLPB");
 926                 break;
 927         }
 928
 929         printk(KERN_DEBUG "Found %s %s [%p]\n", type_string, name, handle);
 930 #endif                          /*CONFIG_ACPI_DEBUG_OUTPUT */
 931 }
 932
 933 static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
 934 {
 935         int result = 0;
 936         struct acpi_driver *driver;
 937
 938         ACPI_FUNCTION_TRACE("acpi_bus_remove");
 939
 940         if (!dev)
 941                 return_VALUE(-EINVAL);
 942
 943         driver = dev->driver;
 944
 945         if ((driver) && (driver->ops.remove)) {
 946
 947                 if (driver->ops.stop) {
 948                         result = driver->ops.stop(dev, ACPI_BUS_REMOVAL_EJECT);
 949                         if (result)
 950                                 return_VALUE(result);
 951                 }
 952
 953                 result = dev->driver->ops.remove(dev, ACPI_BUS_REMOVAL_EJECT);
 954                 if (result) {
 955                         return_VALUE(result);
 956                 }
 957
 958                 atomic_dec(&dev->driver->references);
 959                 dev->driver = NULL;
 960                 acpi_driver_data(dev) = NULL;
 961         }
 962
 963         if (!rmdevice)
 964                 return_VALUE(0);
 965
 966         if (dev->flags.bus_address) {
 967                 if ((dev->parent) && (dev->parent->ops.unbind))
 968                         dev->parent->ops.unbind(dev);
 969         }
 970
 971         acpi_device_unregister(dev, ACPI_BUS_REMOVAL_EJECT);
 972
 973         return_VALUE(0);
 974 }
 975
 976 static int
 977 acpi_add_single_object(struct acpi_device **child,
 978                        struct acpi_device *parent, acpi_handle handle, int type)
 979 {
 980         int result = 0;
 981         struct acpi_device *device = NULL;
 982
 983         ACPI_FUNCTION_TRACE("acpi_add_single_object");
 984
 985         if (!child)
 986                 return_VALUE(-EINVAL);
 987
 988         device = kmalloc(sizeof(struct acpi_device), GFP_KERNEL);
 989         if (!device) {
 990                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Memory allocation error\n"));
 991                 return_VALUE(-ENOMEM);
 992         }
 993         memset(device, 0, sizeof(struct acpi_device));
 994
 995         device->handle = handle;
 996         device->parent = parent;
 997
 998         acpi_device_get_busid(device, handle, type);
 999
1000         /*
1001          * Flags
1002          * -----
1003          * Get prior to calling acpi_bus_get_status() so we know whether
1004          * or not _STA is present.  Note that we only look for object
1005          * handles -- cannot evaluate objects until we know the device is
1006          * present and properly initialized.
1007          */
1008         result = acpi_bus_get_flags(device);
1009         if (result)
1010                 goto end;
1011
1012         /*
1013          * Status
1014          * ------
1015          * See if the device is present.  We always assume that non-Device
1016          * and non-Processor objects (e.g. thermal zones, power resources,
1017          * etc.) are present, functioning, etc. (at least when parent object
1018          * is present).  Note that _STA has a different meaning for some
1019          * objects (e.g. power resources) so we need to be careful how we use
1020          * it.
1021          */
1022         switch (type) {
1023         case ACPI_BUS_TYPE_PROCESSOR:
1024         case ACPI_BUS_TYPE_DEVICE:
1025                 result = acpi_bus_get_status(device);
1026                 if (ACPI_FAILURE(result) || !device->status.present) {
1027                         result = -ENOENT;
1028                         goto end;
1029                 }
1030                 break;
1031         default:
1032                 STRUCT_TO_INT(device->status) = 0x0F;
1033                 break;
1034         }
1035
1036         /*
1037          * Initialize Device
1038          * -----------------
1039          * TBD: Synch with Core's enumeration/initialization process.
1040          */
1041
1042         /*
1043          * Hardware ID, Unique ID, & Bus Address
1044          * -------------------------------------
1045          */
1046         acpi_device_set_id(device, parent, handle, type);
1047
1048         /*
1049          * Power Management
1050          * ----------------
1051          */
1052         if (device->flags.power_manageable) {
1053                 result = acpi_bus_get_power_flags(device);
1054                 if (result)
1055                         goto end;
1056         }
1057
1058         /*
1059          * Wakeup device management
1060          *-----------------------
1061          */
1062         if (device->flags.wake_capable) {
1063                 result = acpi_bus_get_wakeup_device_flags(device);
1064                 if (result)
1065                         goto end;
1066         }
1067
1068         /*
1069          * Performance Management
1070          * ----------------------
1071          */
1072         if (device->flags.performance_manageable) {
1073                 result = acpi_bus_get_perf_flags(device);
1074                 if (result)
1075                         goto end;
1076         }
1077
1078         if ((result = acpi_device_set_context(device, type)))
1079                 goto end;
1080
1081         acpi_device_get_debug_info(device, handle, type);
1082
1083         acpi_device_register(device, parent);
1084
1085         /*
1086          * Bind _ADR-Based Devices
1087          * -----------------------
1088          * If there's a a bus address (_ADR) then we utilize the parent's
1089          * 'bind' function (if exists) to bind the ACPI- and natively-
1090          * enumerated device representations.
1091          */
1092         if (device->flags.bus_address) {
1093                 if (device->parent && device->parent->ops.bind)
1094                         device->parent->ops.bind(device);
1095         }
1096
1097         /*
1098          * Locate & Attach Driver
1099          * ----------------------
1100          * If there's a hardware id (_HID) or compatible ids (_CID) we check
1101          * to see if there's a driver installed for this kind of device.  Note
1102          * that drivers can install before or after a device is enumerated.
1103          *
1104          * TBD: Assumes LDM provides driver hot-plug capability.
1105          */
1106         acpi_bus_find_driver(device);
1107
1108       end:
1109         if (!result)
1110                 *child = device;
1111         else {
1112                 kfree(device->pnp.cid_list);
1113                 kfree(device);
1114         }
1115
1116         return_VALUE(result);
1117 }
1118
1119 static int acpi_bus_scan(struct acpi_device *start, struct acpi_bus_ops *ops)
1120 {
1121         acpi_status status = AE_OK;
1122         struct acpi_device *parent = NULL;
1123         struct acpi_device *child = NULL;
1124         acpi_handle phandle = NULL;
1125         acpi_handle chandle = NULL;
1126         acpi_object_type type = 0;
1127         u32 level = 1;
1128
1129         ACPI_FUNCTION_TRACE("acpi_bus_scan");
1130
1131         if (!start)
1132                 return_VALUE(-EINVAL);
1133
1134         parent = start;
1135         phandle = start->handle;
1136
1137         /*
1138          * Parse through the ACPI namespace, identify all 'devices', and
1139          * create a new 'struct acpi_device' for each.
1140          */
1141         while ((level > 0) && parent) {
1142
1143                 status = acpi_get_next_object(ACPI_TYPE_ANY, phandle,
1144                                               chandle, &chandle);
1145
1146                 /*
1147                  * If this scope is exhausted then move our way back up.
1148                  */
1149                 if (ACPI_FAILURE(status)) {
1150                         level--;
1151                         chandle = phandle;
1152                         acpi_get_parent(phandle, &phandle);
1153                         if (parent->parent)
1154                                 parent = parent->parent;
1155                         continue;
1156                 }
1157
1158                 status = acpi_get_type(chandle, &type);
1159                 if (ACPI_FAILURE(status))
1160                         continue;
1161
1162                 /*
1163                  * If this is a scope object then parse it (depth-first).
1164                  */
1165                 if (type == ACPI_TYPE_LOCAL_SCOPE) {
1166                         level++;
1167                         phandle = chandle;
1168                         chandle = NULL;
1169                         continue;
1170                 }
1171
1172                 /*
1173                  * We're only interested in objects that we consider 'devices'.
1174                  */
1175                 switch (type) {
1176                 case ACPI_TYPE_DEVICE:
1177                         type = ACPI_BUS_TYPE_DEVICE;
1178                         break;
1179                 case ACPI_TYPE_PROCESSOR:
1180                         type = ACPI_BUS_TYPE_PROCESSOR;
1181                         break;
1182                 case ACPI_TYPE_THERMAL:
1183                         type = ACPI_BUS_TYPE_THERMAL;
1184                         break;
1185                 case ACPI_TYPE_POWER:
1186                         type = ACPI_BUS_TYPE_POWER;
1187                         break;
1188                 default:
1189                         continue;
1190                 }
1191
1192                 if (ops->acpi_op_add)
1193                         status = acpi_add_single_object(&child, parent,
1194                                                         chandle, type);
1195                 else
1196                         status = acpi_bus_get_device(chandle, &child);
1197
1198                 if (ACPI_FAILURE(status))
1199                         continue;
1200
1201                 if (ops->acpi_op_start) {
1202                         status = acpi_start_single_object(child);
1203                         if (ACPI_FAILURE(status))
1204                                 continue;
1205                 }
1206
1207                 /*
1208                  * If the device is present, enabled, and functioning then
1209                  * parse its scope (depth-first).  Note that we need to
1210                  * represent absent devices to facilitate PnP notifications
1211                  * -- but only the subtree head (not all of its children,
1212                  * which will be enumerated when the parent is inserted).
1213                  *
1214                  * TBD: Need notifications and other detection mechanisms
1215                  *      in place before we can fully implement this.
1216                  */
1217                 if (child->status.present) {
1218                         status = acpi_get_next_object(ACPI_TYPE_ANY, chandle,
1219                                                       NULL, NULL);
1220                         if (ACPI_SUCCESS(status)) {
1221                                 level++;
1222                                 phandle = chandle;
1223                                 chandle = NULL;
1224                                 parent = child;
1225                         }
1226                 }
1227         }
1228
1229         return_VALUE(0);
1230 }
1231
1232 int
1233 acpi_bus_add(struct acpi_device **child,
1234              struct acpi_device *parent, acpi_handle handle, int type)
1235 {
1236         int result;
1237         struct acpi_bus_ops ops;
1238
1239         ACPI_FUNCTION_TRACE("acpi_bus_add");
1240
1241         result = acpi_add_single_object(child, parent, handle, type);
1242         if (!result) {
1243                 memset(&ops, 0, sizeof(ops));
1244                 ops.acpi_op_add = 1;
1245                 result = acpi_bus_scan(*child, &ops);
1246         }
1247         return_VALUE(result);
1248 }
1249
1250 EXPORT_SYMBOL(acpi_bus_add);
1251
1252 int acpi_bus_start(struct acpi_device *device)
1253 {
1254         int result;
1255         struct acpi_bus_ops ops;
1256
1257         ACPI_FUNCTION_TRACE("acpi_bus_start");
1258
1259         if (!device)
1260                 return_VALUE(-EINVAL);
1261
1262         result = acpi_start_single_object(device);
1263         if (!result) {
1264                 memset(&ops, 0, sizeof(ops));
1265                 ops.acpi_op_start = 1;
1266                 result = acpi_bus_scan(device, &ops);
1267         }
1268         return_VALUE(result);
1269 }
1270
1271 EXPORT_SYMBOL(acpi_bus_start);
1272
1273 int acpi_bus_trim(struct acpi_device *start, int rmdevice)
1274 {
1275         acpi_status status;
1276         struct acpi_device *parent, *child;
1277         acpi_handle phandle, chandle;
1278         acpi_object_type type;
1279         u32 level = 1;
1280         int err = 0;
1281
1282         parent = start;
1283         phandle = start->handle;
1284         child = chandle = NULL;
1285
1286         while ((level > 0) && parent && (!err)) {
1287                 status = acpi_get_next_object(ACPI_TYPE_ANY, phandle,
1288                                               chandle, &chandle);
1289
1290                 /*
1291                  * If this scope is exhausted then move our way back up.
1292                  */
1293                 if (ACPI_FAILURE(status)) {
1294                         level--;
1295                         chandle = phandle;
1296                         acpi_get_parent(phandle, &phandle);
1297                         child = parent;
1298                         parent = parent->parent;
1299
1300                         if (level == 0)
1301                                 err = acpi_bus_remove(child, rmdevice);
1302                         else
1303                                 err = acpi_bus_remove(child, 1);
1304
1305                         continue;
1306                 }
1307
1308                 status = acpi_get_type(chandle, &type);
1309                 if (ACPI_FAILURE(status)) {
1310                         continue;
1311                 }
1312                 /*
1313                  * If there is a device corresponding to chandle then
1314                  * parse it (depth-first).
1315                  */
1316                 if (acpi_bus_get_device(chandle, &child) == 0) {
1317                         level++;
1318                         phandle = chandle;
1319                         chandle = NULL;
1320                         parent = child;
1321                 }
1322                 continue;
1323         }
1324         return err;
1325 }
1326 EXPORT_SYMBOL_GPL(acpi_bus_trim);
1327
1328
1329 static int acpi_bus_scan_fixed(struct acpi_device *root)
1330 {
1331         int result = 0;
1332         struct acpi_device *device = NULL;
1333
1334         ACPI_FUNCTION_TRACE("acpi_bus_scan_fixed");
1335
1336         if (!root)
1337                 return_VALUE(-ENODEV);
1338
1339         /*
1340          * Enumerate all fixed-feature devices.
1341          */
1342         if (acpi_fadt.pwr_button == 0) {
1343                 result = acpi_add_single_object(&device, acpi_root,
1344                                                 NULL,
1345                                                 ACPI_BUS_TYPE_POWER_BUTTON);
1346                 if (!result)
1347                         result = acpi_start_single_object(device);
1348         }
1349
1350         if (acpi_fadt.sleep_button == 0) {
1351                 result = acpi_add_single_object(&device, acpi_root,
1352                                                 NULL,
1353                                                 ACPI_BUS_TYPE_SLEEP_BUTTON);
1354                 if (!result)
1355                         result = acpi_start_single_object(device);
1356         }
1357
1358         return_VALUE(result);
1359 }
1360
1361 static int __init acpi_scan_init(void)
1362 {
1363         int result;
1364         struct acpi_bus_ops ops;
1365
1366         ACPI_FUNCTION_TRACE("acpi_scan_init");
1367
1368         if (acpi_disabled)
1369                 return_VALUE(0);
1370
1371         kset_register(&acpi_namespace_kset);
1372
1373         /*
1374          * Create the root device in the bus's device tree
1375          */
1376         result = acpi_add_single_object(&acpi_root, NULL, ACPI_ROOT_OBJECT,
1377                                         ACPI_BUS_TYPE_SYSTEM);
1378         if (result)
1379                 goto Done;
1380
1381         result = acpi_start_single_object(acpi_root);
1382
1383         /*
1384          * Enumerate devices in the ACPI namespace.
1385          */
1386         result = acpi_bus_scan_fixed(acpi_root);
1387         if (!result) {
1388                 memset(&ops, 0, sizeof(ops));
1389                 ops.acpi_op_add = 1;
1390                 ops.acpi_op_start = 1;
1391                 result = acpi_bus_scan(acpi_root, &ops);
1392         }
1393
1394         if (result)
1395                 acpi_device_unregister(acpi_root, ACPI_BUS_REMOVAL_NORMAL);
1396
1397       Done:
1398         return_VALUE(result);
1399 }
1400
1401 subsys_initcall(acpi_scan_init);