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 static int acpi_bus_trim(struct acpi_device *start, int rmdevice);
  27
  28 static void acpi_device_release(struct kobject *kobj)
  29 {
  30         struct acpi_device *dev = container_of(kobj, struct acpi_device, kobj);
  31         kfree(dev->pnp.cid_list);
  32         kfree(dev);
  33 }
  34
  35 struct acpi_device_attribute {
  36         struct attribute attr;
  37          ssize_t(*show) (struct acpi_device *, char *);
  38          ssize_t(*store) (struct acpi_device *, const char *, size_t);
  39 };
  40
  41 typedef void acpi_device_sysfs_files(struct kobject *,
  42                                      const struct attribute *);
  43
  44 static void setup_sys_fs_device_files(struct acpi_device *dev,
  45                                       acpi_device_sysfs_files * func);
  46
  47 #define create_sysfs_device_files(dev)  \
  48         setup_sys_fs_device_files(dev, (acpi_device_sysfs_files *)&sysfs_create_file)
  49 #define remove_sysfs_device_files(dev)  \
  50         setup_sys_fs_device_files(dev, (acpi_device_sysfs_files *)&sysfs_remove_file)
  51
  52 #define to_acpi_device(n) container_of(n, struct acpi_device, kobj)
  53 #define to_handle_attr(n) container_of(n, struct acpi_device_attribute, attr);
  54
  55 static ssize_t acpi_device_attr_show(struct kobject *kobj,
  56                                      struct attribute *attr, char *buf)
  57 {
  58         struct acpi_device *device = to_acpi_device(kobj);
  59         struct acpi_device_attribute *attribute = to_handle_attr(attr);
  60         return attribute->show ? attribute->show(device, buf) : -EIO;
  61 }
  62 static ssize_t acpi_device_attr_store(struct kobject *kobj,
  63                                       struct attribute *attr, const char *buf,
  64                                       size_t len)
  65 {
  66         struct acpi_device *device = to_acpi_device(kobj);
  67         struct acpi_device_attribute *attribute = to_handle_attr(attr);
  68         return attribute->store ? attribute->store(device, buf, len) : -EIO;
  69 }
  70
  71 static struct sysfs_ops acpi_device_sysfs_ops = {
  72         .show = acpi_device_attr_show,
  73         .store = acpi_device_attr_store,
  74 };
  75
  76 static struct kobj_type ktype_acpi_ns = {
  77         .sysfs_ops = &acpi_device_sysfs_ops,
  78         .release = acpi_device_release,
  79 };
  80
  81 static int namespace_uevent(struct kset *kset, struct kobject *kobj,
  82                              char **envp, int num_envp, char *buffer,
  83                              int buffer_size)
  84 {
  85         struct acpi_device *dev = to_acpi_device(kobj);
  86         int i = 0;
  87         int len = 0;
  88
  89         if (!dev->driver)
  90                 return 0;
  91
  92         if (add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &len,
  93                            "PHYSDEVDRIVER=%s", dev->driver->name))
  94                 return -ENOMEM;
  95
  96         envp[i] = NULL;
  97
  98         return 0;
  99 }
 100
 101 static struct kset_uevent_ops namespace_uevent_ops = {
 102         .uevent = &namespace_uevent,
 103 };
 104
 105 static struct kset acpi_namespace_kset = {
 106         .kobj = {
 107                  .name = "namespace",
 108                  },
 109         .subsys = &acpi_subsys,
 110         .ktype = &ktype_acpi_ns,
 111         .uevent_ops = &namespace_uevent_ops,
 112 };
 113
 114 static void acpi_device_register(struct acpi_device *device,
 115                                  struct acpi_device *parent)
 116 {
 117         /*
 118          * Linkage
 119          * -------
 120          * Link this device to its parent and siblings.
 121          */
 122         INIT_LIST_HEAD(&device->children);
 123         INIT_LIST_HEAD(&device->node);
 124         INIT_LIST_HEAD(&device->g_list);
 125         INIT_LIST_HEAD(&device->wakeup_list);
 126
 127         spin_lock(&acpi_device_lock);
 128         if (device->parent) {
 129                 list_add_tail(&device->node, &device->parent->children);
 130                 list_add_tail(&device->g_list, &device->parent->g_list);
 131         } else
 132                 list_add_tail(&device->g_list, &acpi_device_list);
 133         if (device->wakeup.flags.valid)
 134                 list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);
 135         spin_unlock(&acpi_device_lock);
 136
 137         strlcpy(device->kobj.name, device->pnp.bus_id, KOBJ_NAME_LEN);
 138         if (parent)
 139                 device->kobj.parent = &parent->kobj;
 140         device->kobj.ktype = &ktype_acpi_ns;
 141         device->kobj.kset = &acpi_namespace_kset;
 142         kobject_register(&device->kobj);
 143         create_sysfs_device_files(device);
 144 }
 145
 146 static int acpi_device_unregister(struct acpi_device *device, int type)
 147 {
 148         spin_lock(&acpi_device_lock);
 149         if (device->parent) {
 150                 list_del(&device->node);
 151                 list_del(&device->g_list);
 152         } else
 153                 list_del(&device->g_list);
 154
 155         list_del(&device->wakeup_list);
 156
 157         spin_unlock(&acpi_device_lock);
 158
 159         acpi_detach_data(device->handle, acpi_bus_data_handler);
 160         remove_sysfs_device_files(device);
 161         kobject_unregister(&device->kobj);
 162         return 0;
 163 }
 164
 165 void acpi_bus_data_handler(acpi_handle handle, u32 function, void *context)
 166 {
 167         ACPI_FUNCTION_TRACE("acpi_bus_data_handler");
 168
 169         /* TBD */
 170
 171         return_VOID;
 172 }
 173
 174 static int acpi_bus_get_power_flags(struct acpi_device *device)
 175 {
 176         acpi_status status = 0;
 177         acpi_handle handle = NULL;
 178         u32 i = 0;
 179
 180         ACPI_FUNCTION_TRACE("acpi_bus_get_power_flags");
 181
 182         /*
 183          * Power Management Flags
 184          */
 185         status = acpi_get_handle(device->handle, "_PSC", &handle);
 186         if (ACPI_SUCCESS(status))
 187                 device->power.flags.explicit_get = 1;
 188         status = acpi_get_handle(device->handle, "_IRC", &handle);
 189         if (ACPI_SUCCESS(status))
 190                 device->power.flags.inrush_current = 1;
 191
 192         /*
 193          * Enumerate supported power management states
 194          */
 195         for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3; i++) {
 196                 struct acpi_device_power_state *ps = &device->power.states[i];
 197                 char object_name[5] = { '_', 'P', 'R', '0' + i, '\0' };
 198
 199                 /* Evaluate "_PRx" to se if power resources are referenced */
 200                 acpi_evaluate_reference(device->handle, object_name, NULL,
 201                                         &ps->resources);
 202                 if (ps->resources.count) {
 203                         device->power.flags.power_resources = 1;
 204                         ps->flags.valid = 1;
 205                 }
 206
 207                 /* Evaluate "_PSx" to see if we can do explicit sets */
 208                 object_name[2] = 'S';
 209                 status = acpi_get_handle(device->handle, object_name, &handle);
 210                 if (ACPI_SUCCESS(status)) {
 211                         ps->flags.explicit_set = 1;
 212                         ps->flags.valid = 1;
 213                 }
 214
 215                 /* State is valid if we have some power control */
 216                 if (ps->resources.count || ps->flags.explicit_set)
 217                         ps->flags.valid = 1;
 218
 219                 ps->power = -1; /* Unknown - driver assigned */
 220                 ps->latency = -1;       /* Unknown - driver assigned */
 221         }
 222
 223         /* Set defaults for D0 and D3 states (always valid) */
 224         device->power.states[ACPI_STATE_D0].flags.valid = 1;
 225         device->power.states[ACPI_STATE_D0].power = 100;
 226         device->power.states[ACPI_STATE_D3].flags.valid = 1;
 227         device->power.states[ACPI_STATE_D3].power = 0;
 228
 229         /* TBD: System wake support and resource requirements. */
 230
 231         device->power.state = ACPI_STATE_UNKNOWN;
 232
 233         return_VALUE(0);
 234 }
 235
 236 int acpi_match_ids(struct acpi_device *device, char *ids)
 237 {
 238         int error = 0;
 239         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 240
 241         if (device->flags.hardware_id)
 242                 if (strstr(ids, device->pnp.hardware_id))
 243                         goto Done;
 244
 245         if (device->flags.compatible_ids) {
 246                 struct acpi_compatible_id_list *cid_list = device->pnp.cid_list;
 247                 int i;
 248
 249                 /* compare multiple _CID entries against driver ids */
 250                 for (i = 0; i < cid_list->count; i++) {
 251                         if (strstr(ids, cid_list->id[i].value))
 252                                 goto Done;
 253                 }
 254         }
 255         error = -ENOENT;
 256
 257       Done:
 258         if (buffer.pointer)
 259                 acpi_os_free(buffer.pointer);
 260         return error;
 261 }
 262
 263 static acpi_status
 264 acpi_bus_extract_wakeup_device_power_package(struct acpi_device *device,
 265                                              union acpi_object *package)
 266 {
 267         int i = 0;
 268         union acpi_object *element = NULL;
 269
 270         if (!device || !package || (package->package.count < 2))
 271                 return AE_BAD_PARAMETER;
 272
 273         element = &(package->package.elements[0]);
 274         if (!element)
 275                 return AE_BAD_PARAMETER;
 276         if (element->type == ACPI_TYPE_PACKAGE) {
 277                 if ((element->package.count < 2) ||
 278                     (element->package.elements[0].type !=
 279                      ACPI_TYPE_LOCAL_REFERENCE)
 280                     || (element->package.elements[1].type != ACPI_TYPE_INTEGER))
 281                         return AE_BAD_DATA;
 282                 device->wakeup.gpe_device =
 283                     element->package.elements[0].reference.handle;
 284                 device->wakeup.gpe_number =
 285                     (u32) element->package.elements[1].integer.value;
 286         } else if (element->type == ACPI_TYPE_INTEGER) {
 287                 device->wakeup.gpe_number = element->integer.value;
 288         } else
 289                 return AE_BAD_DATA;
 290
 291         element = &(package->package.elements[1]);
 292         if (element->type != ACPI_TYPE_INTEGER) {
 293                 return AE_BAD_DATA;
 294         }
 295         device->wakeup.sleep_state = element->integer.value;
 296
 297         if ((package->package.count - 2) > ACPI_MAX_HANDLES) {
 298                 return AE_NO_MEMORY;
 299         }
 300         device->wakeup.resources.count = package->package.count - 2;
 301         for (i = 0; i < device->wakeup.resources.count; i++) {
 302                 element = &(package->package.elements[i + 2]);
 303                 if (element->type != ACPI_TYPE_ANY) {
 304                         return AE_BAD_DATA;
 305                 }
 306
 307                 device->wakeup.resources.handles[i] = element->reference.handle;
 308         }
 309
 310         return AE_OK;
 311 }
 312
 313 static int acpi_bus_get_wakeup_device_flags(struct acpi_device *device)
 314 {
 315         acpi_status status = 0;
 316         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 317         union acpi_object *package = NULL;
 318
 319         ACPI_FUNCTION_TRACE("acpi_bus_get_wakeup_flags");
 320
 321         /* _PRW */
 322         status = acpi_evaluate_object(device->handle, "_PRW", NULL, &buffer);
 323         if (ACPI_FAILURE(status)) {
 324                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error evaluating _PRW\n"));
 325                 goto end;
 326         }
 327
 328         package = (union acpi_object *)buffer.pointer;
 329         status = acpi_bus_extract_wakeup_device_power_package(device, package);
 330         if (ACPI_FAILURE(status)) {
 331                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 332                                   "Error extracting _PRW package\n"));
 333                 goto end;
 334         }
 335
 336         acpi_os_free(buffer.pointer);
 337
 338         device->wakeup.flags.valid = 1;
 339         /* Power button, Lid switch always enable wakeup */
 340         if (!acpi_match_ids(device, "PNP0C0D,PNP0C0C,PNP0C0E"))
 341                 device->wakeup.flags.run_wake = 1;
 342
 343       end:
 344         if (ACPI_FAILURE(status))
 345                 device->flags.wake_capable = 0;
 346         return_VALUE(0);
 347 }
 348
 349 /* --------------------------------------------------------------------------
 350                 ACPI sysfs device file support
 351    -------------------------------------------------------------------------- */
 352 static ssize_t acpi_eject_store(struct acpi_device *device,
 353                                 const char *buf, size_t count);
 354
 355 #define ACPI_DEVICE_ATTR(_name,_mode,_show,_store) \
 356 static struct acpi_device_attribute acpi_device_attr_##_name = \
 357                 __ATTR(_name, _mode, _show, _store)
 358
 359 ACPI_DEVICE_ATTR(eject, 0200, NULL, acpi_eject_store);
 360
 361 /**
 362  * setup_sys_fs_device_files - sets up the device files under device namespace
 363  * @dev:        acpi_device object
 364  * @func:       function pointer to create or destroy the device file
 365  */
 366 static void
 367 setup_sys_fs_device_files(struct acpi_device *dev,
 368                           acpi_device_sysfs_files * func)
 369 {
 370         acpi_status status;
 371         acpi_handle temp = NULL;
 372
 373         /*
 374          * If device has _EJ0, 'eject' file is created that is used to trigger
 375          * hot-removal function from userland.
 376          */
 377         status = acpi_get_handle(dev->handle, "_EJ0", &temp);
 378         if (ACPI_SUCCESS(status))
 379                 (*(func)) (&dev->kobj, &acpi_device_attr_eject.attr);
 380 }
 381
 382 static int acpi_eject_operation(acpi_handle handle, int lockable)
 383 {
 384         struct acpi_object_list arg_list;
 385         union acpi_object arg;
 386         acpi_status status = AE_OK;
 387
 388         /*
 389          * TBD: evaluate _PS3?
 390          */
 391
 392         if (lockable) {
 393                 arg_list.count = 1;
 394                 arg_list.pointer = &arg;
 395                 arg.type = ACPI_TYPE_INTEGER;
 396                 arg.integer.value = 0;
 397                 acpi_evaluate_object(handle, "_LCK", &arg_list, NULL);
 398         }
 399
 400         arg_list.count = 1;
 401         arg_list.pointer = &arg;
 402         arg.type = ACPI_TYPE_INTEGER;
 403         arg.integer.value = 1;
 404
 405         /*
 406          * TBD: _EJD support.
 407          */
 408
 409         status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL);
 410         if (ACPI_FAILURE(status)) {
 411                 return (-ENODEV);
 412         }
 413
 414         return (0);
 415 }
 416
 417 static ssize_t
 418 acpi_eject_store(struct acpi_device *device, const char *buf, size_t count)
 419 {
 420         int result;
 421         int ret = count;
 422         int islockable;
 423         acpi_status status;
 424         acpi_handle handle;
 425         acpi_object_type type = 0;
 426
 427         if ((!count) || (buf[0] != '1')) {
 428                 return -EINVAL;
 429         }
 430 #ifndef FORCE_EJECT
 431         if (device->driver == NULL) {
 432                 ret = -ENODEV;
 433                 goto err;
 434         }
 435 #endif
 436         status = acpi_get_type(device->handle, &type);
 437         if (ACPI_FAILURE(status) || (!device->flags.ejectable)) {
 438                 ret = -ENODEV;
 439                 goto err;
 440         }
 441
 442         islockable = device->flags.lockable;
 443         handle = device->handle;
 444
 445         if (type == ACPI_TYPE_PROCESSOR)
 446                 result = acpi_bus_trim(device, 0);
 447         else
 448                 result = acpi_bus_trim(device, 1);
 449
 450         if (!result)
 451                 result = acpi_eject_operation(handle, islockable);
 452
 453         if (result) {
 454                 ret = -EBUSY;
 455         }
 456       err:
 457         return ret;
 458 }
 459
 460 /* --------------------------------------------------------------------------
 461                               Performance Management
 462    -------------------------------------------------------------------------- */
 463
 464 static int acpi_bus_get_perf_flags(struct acpi_device *device)
 465 {
 466         device->performance.state = ACPI_STATE_UNKNOWN;
 467         return 0;
 468 }
 469
 470 /* --------------------------------------------------------------------------
 471                                  Driver Management
 472    -------------------------------------------------------------------------- */
 473
 474 static LIST_HEAD(acpi_bus_drivers);
 475 static DECLARE_MUTEX(acpi_bus_drivers_lock);
 476
 477 /**
 478  * acpi_bus_match
 479  * --------------
 480  * Checks the device's hardware (_HID) or compatible (_CID) ids to see if it
 481  * matches the specified driver's criteria.
 482  */
 483 static int
 484 acpi_bus_match(struct acpi_device *device, struct acpi_driver *driver)
 485 {
 486         if (driver && driver->ops.match)
 487                 return driver->ops.match(device, driver);
 488         return acpi_match_ids(device, driver->ids);
 489 }
 490
 491 /**
 492  * acpi_bus_driver_init
 493  * --------------------
 494  * Used to initialize a device via its device driver.  Called whenever a
 495  * driver is bound to a device.  Invokes the driver's add() and start() ops.
 496  */
 497 static int
 498 acpi_bus_driver_init(struct acpi_device *device, struct acpi_driver *driver)
 499 {
 500         int result = 0;
 501
 502         ACPI_FUNCTION_TRACE("acpi_bus_driver_init");
 503
 504         if (!device || !driver)
 505                 return_VALUE(-EINVAL);
 506
 507         if (!driver->ops.add)
 508                 return_VALUE(-ENOSYS);
 509
 510         result = driver->ops.add(device);
 511         if (result) {
 512                 device->driver = NULL;
 513                 acpi_driver_data(device) = NULL;
 514                 return_VALUE(result);
 515         }
 516
 517         device->driver = driver;
 518
 519         /*
 520          * TBD - Configuration Management: Assign resources to device based
 521          * upon possible configuration and currently allocated resources.
 522          */
 523
 524         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 525                           "Driver successfully bound to device\n"));
 526         return_VALUE(0);
 527 }
 528
 529 static int acpi_start_single_object(struct acpi_device *device)
 530 {
 531         int result = 0;
 532         struct acpi_driver *driver;
 533
 534         ACPI_FUNCTION_TRACE("acpi_start_single_object");
 535
 536         if (!(driver = device->driver))
 537                 return_VALUE(0);
 538
 539         if (driver->ops.start) {
 540                 result = driver->ops.start(device);
 541                 if (result && driver->ops.remove)
 542                         driver->ops.remove(device, ACPI_BUS_REMOVAL_NORMAL);
 543         }
 544
 545         return_VALUE(result);
 546 }
 547
 548 static int acpi_driver_attach(struct acpi_driver *drv)
 549 {
 550         struct list_head *node, *next;
 551         int count = 0;
 552
 553         ACPI_FUNCTION_TRACE("acpi_driver_attach");
 554
 555         spin_lock(&acpi_device_lock);
 556         list_for_each_safe(node, next, &acpi_device_list) {
 557                 struct acpi_device *dev =
 558                     container_of(node, struct acpi_device, g_list);
 559
 560                 if (dev->driver || !dev->status.present)
 561                         continue;
 562                 spin_unlock(&acpi_device_lock);
 563
 564                 if (!acpi_bus_match(dev, drv)) {
 565                         if (!acpi_bus_driver_init(dev, drv)) {
 566                                 acpi_start_single_object(dev);
 567                                 atomic_inc(&drv->references);
 568                                 count++;
 569                                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 570                                                   "Found driver [%s] for device [%s]\n",
 571                                                   drv->name, dev->pnp.bus_id));
 572                         }
 573                 }
 574                 spin_lock(&acpi_device_lock);
 575         }
 576         spin_unlock(&acpi_device_lock);
 577         return_VALUE(count);
 578 }
 579
 580 static int acpi_driver_detach(struct acpi_driver *drv)
 581 {
 582         struct list_head *node, *next;
 583
 584         ACPI_FUNCTION_TRACE("acpi_driver_detach");
 585
 586         spin_lock(&acpi_device_lock);
 587         list_for_each_safe(node, next, &acpi_device_list) {
 588                 struct acpi_device *dev =
 589                     container_of(node, struct acpi_device, g_list);
 590
 591                 if (dev->driver == drv) {
 592                         spin_unlock(&acpi_device_lock);
 593                         if (drv->ops.remove)
 594                                 drv->ops.remove(dev, ACPI_BUS_REMOVAL_NORMAL);
 595                         spin_lock(&acpi_device_lock);
 596                         dev->driver = NULL;
 597                         dev->driver_data = NULL;
 598                         atomic_dec(&drv->references);
 599                 }
 600         }
 601         spin_unlock(&acpi_device_lock);
 602         return_VALUE(0);
 603 }
 604
 605 /**
 606  * acpi_bus_register_driver
 607  * ------------------------
 608  * Registers a driver with the ACPI bus.  Searches the namespace for all
 609  * devices that match the driver's criteria and binds.  Returns the
 610  * number of devices that were claimed by the driver, or a negative
 611  * error status for failure.
 612  */
 613 int acpi_bus_register_driver(struct acpi_driver *driver)
 614 {
 615         int count;
 616
 617         ACPI_FUNCTION_TRACE("acpi_bus_register_driver");
 618
 619         if (acpi_disabled)
 620                 return_VALUE(-ENODEV);
 621
 622         if (!driver)
 623                 return_VALUE(-EINVAL);
 624
 625         spin_lock(&acpi_device_lock);
 626         list_add_tail(&driver->node, &acpi_bus_drivers);
 627         spin_unlock(&acpi_device_lock);
 628         count = acpi_driver_attach(driver);
 629
 630         return_VALUE(count);
 631 }
 632
 633 EXPORT_SYMBOL(acpi_bus_register_driver);
 634
 635 /**
 636  * acpi_bus_unregister_driver
 637  * --------------------------
 638  * Unregisters a driver with the ACPI bus.  Searches the namespace for all
 639  * devices that match the driver's criteria and unbinds.
 640  */
 641 int acpi_bus_unregister_driver(struct acpi_driver *driver)
 642 {
 643         int error = 0;
 644
 645         ACPI_FUNCTION_TRACE("acpi_bus_unregister_driver");
 646
 647         if (driver) {
 648                 acpi_driver_detach(driver);
 649
 650                 if (!atomic_read(&driver->references)) {
 651                         spin_lock(&acpi_device_lock);
 652                         list_del_init(&driver->node);
 653                         spin_unlock(&acpi_device_lock);
 654                 }
 655         } else
 656                 error = -EINVAL;
 657         return_VALUE(error);
 658 }
 659
 660 EXPORT_SYMBOL(acpi_bus_unregister_driver);
 661
 662 /**
 663  * acpi_bus_find_driver
 664  * --------------------
 665  * Parses the list of registered drivers looking for a driver applicable for
 666  * the specified device.
 667  */
 668 static int acpi_bus_find_driver(struct acpi_device *device)
 669 {
 670         int result = 0;
 671         struct list_head *node, *next;
 672
 673         ACPI_FUNCTION_TRACE("acpi_bus_find_driver");
 674
 675         spin_lock(&acpi_device_lock);
 676         list_for_each_safe(node, next, &acpi_bus_drivers) {
 677                 struct acpi_driver *driver =
 678                     container_of(node, struct acpi_driver, node);
 679
 680                 atomic_inc(&driver->references);
 681                 spin_unlock(&acpi_device_lock);
 682                 if (!acpi_bus_match(device, driver)) {
 683                         result = acpi_bus_driver_init(device, driver);
 684                         if (!result)
 685                                 goto Done;
 686                 }
 687                 atomic_dec(&driver->references);
 688                 spin_lock(&acpi_device_lock);
 689         }
 690         spin_unlock(&acpi_device_lock);
 691
 692       Done:
 693         return_VALUE(result);
 694 }
 695
 696 /* --------------------------------------------------------------------------
 697                                  Device Enumeration
 698    -------------------------------------------------------------------------- */
 699
 700 static int acpi_bus_get_flags(struct acpi_device *device)
 701 {
 702         acpi_status status = AE_OK;
 703         acpi_handle temp = NULL;
 704
 705         ACPI_FUNCTION_TRACE("acpi_bus_get_flags");
 706
 707         /* Presence of _STA indicates 'dynamic_status' */
 708         status = acpi_get_handle(device->handle, "_STA", &temp);
 709         if (ACPI_SUCCESS(status))
 710                 device->flags.dynamic_status = 1;
 711
 712         /* Presence of _CID indicates 'compatible_ids' */
 713         status = acpi_get_handle(device->handle, "_CID", &temp);
 714         if (ACPI_SUCCESS(status))
 715                 device->flags.compatible_ids = 1;
 716
 717         /* Presence of _RMV indicates 'removable' */
 718         status = acpi_get_handle(device->handle, "_RMV", &temp);
 719         if (ACPI_SUCCESS(status))
 720                 device->flags.removable = 1;
 721
 722         /* Presence of _EJD|_EJ0 indicates 'ejectable' */
 723         status = acpi_get_handle(device->handle, "_EJD", &temp);
 724         if (ACPI_SUCCESS(status))
 725                 device->flags.ejectable = 1;
 726         else {
 727                 status = acpi_get_handle(device->handle, "_EJ0", &temp);
 728                 if (ACPI_SUCCESS(status))
 729                         device->flags.ejectable = 1;
 730         }
 731
 732         /* Presence of _LCK indicates 'lockable' */
 733         status = acpi_get_handle(device->handle, "_LCK", &temp);
 734         if (ACPI_SUCCESS(status))
 735                 device->flags.lockable = 1;
 736
 737         /* Presence of _PS0|_PR0 indicates 'power manageable' */
 738         status = acpi_get_handle(device->handle, "_PS0", &temp);
 739         if (ACPI_FAILURE(status))
 740                 status = acpi_get_handle(device->handle, "_PR0", &temp);
 741         if (ACPI_SUCCESS(status))
 742                 device->flags.power_manageable = 1;
 743
 744         /* Presence of _PRW indicates wake capable */
 745         status = acpi_get_handle(device->handle, "_PRW", &temp);
 746         if (ACPI_SUCCESS(status))
 747                 device->flags.wake_capable = 1;
 748
 749         /* TBD: Peformance management */
 750
 751         return_VALUE(0);
 752 }
 753
 754 static void acpi_device_get_busid(struct acpi_device *device,
 755                                   acpi_handle handle, int type)
 756 {
 757         char bus_id[5] = { '?', 0 };
 758         struct acpi_buffer buffer = { sizeof(bus_id), bus_id };
 759         int i = 0;
 760
 761         /*
 762          * Bus ID
 763          * ------
 764          * The device's Bus ID is simply the object name.
 765          * TBD: Shouldn't this value be unique (within the ACPI namespace)?
 766          */
 767         switch (type) {
 768         case ACPI_BUS_TYPE_SYSTEM:
 769                 strcpy(device->pnp.bus_id, "ACPI");
 770                 break;
 771         case ACPI_BUS_TYPE_POWER_BUTTON:
 772                 strcpy(device->pnp.bus_id, "PWRF");
 773                 break;
 774         case ACPI_BUS_TYPE_SLEEP_BUTTON:
 775                 strcpy(device->pnp.bus_id, "SLPF");
 776                 break;
 777         default:
 778                 acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
 779                 /* Clean up trailing underscores (if any) */
 780                 for (i = 3; i > 1; i--) {
 781                         if (bus_id[i] == '_')
 782                                 bus_id[i] = '\0';
 783                         else
 784                                 break;
 785                 }
 786                 strcpy(device->pnp.bus_id, bus_id);
 787                 break;
 788         }
 789 }
 790
 791 static void acpi_device_set_id(struct acpi_device *device,
 792                                struct acpi_device *parent, acpi_handle handle,
 793                                int type)
 794 {
 795         struct acpi_device_info *info;
 796         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 797         char *hid = NULL;
 798         char *uid = NULL;
 799         struct acpi_compatible_id_list *cid_list = NULL;
 800         acpi_status status;
 801
 802         switch (type) {
 803         case ACPI_BUS_TYPE_DEVICE:
 804                 status = acpi_get_object_info(handle, &buffer);
 805                 if (ACPI_FAILURE(status)) {
 806                         printk("%s: Error reading device info\n", __FUNCTION__);
 807                         return;
 808                 }
 809
 810                 info = buffer.pointer;
 811                 if (info->valid & ACPI_VALID_HID)
 812                         hid = info->hardware_id.value;
 813                 if (info->valid & ACPI_VALID_UID)
 814                         uid = info->unique_id.value;
 815                 if (info->valid & ACPI_VALID_CID)
 816                         cid_list = &info->compatibility_id;
 817                 if (info->valid & ACPI_VALID_ADR) {
 818                         device->pnp.bus_address = info->address;
 819                         device->flags.bus_address = 1;
 820                 }
 821                 break;
 822         case ACPI_BUS_TYPE_POWER:
 823                 hid = ACPI_POWER_HID;
 824                 break;
 825         case ACPI_BUS_TYPE_PROCESSOR:
 826                 hid = ACPI_PROCESSOR_HID;
 827                 break;
 828         case ACPI_BUS_TYPE_SYSTEM:
 829                 hid = ACPI_SYSTEM_HID;
 830                 break;
 831         case ACPI_BUS_TYPE_THERMAL:
 832                 hid = ACPI_THERMAL_HID;
 833                 break;
 834         case ACPI_BUS_TYPE_POWER_BUTTON:
 835                 hid = ACPI_BUTTON_HID_POWERF;
 836                 break;
 837         case ACPI_BUS_TYPE_SLEEP_BUTTON:
 838                 hid = ACPI_BUTTON_HID_SLEEPF;
 839                 break;
 840         }
 841
 842         /*
 843          * \_SB
 844          * ----
 845          * Fix for the system root bus device -- the only root-level device.
 846          */
 847         if ((parent == ACPI_ROOT_OBJECT) && (type == ACPI_BUS_TYPE_DEVICE)) {
 848                 hid = ACPI_BUS_HID;
 849                 strcpy(device->pnp.device_name, ACPI_BUS_DEVICE_NAME);
 850                 strcpy(device->pnp.device_class, ACPI_BUS_CLASS);
 851         }
 852
 853         if (hid) {
 854                 strcpy(device->pnp.hardware_id, hid);
 855                 device->flags.hardware_id = 1;
 856         }
 857         if (uid) {
 858                 strcpy(device->pnp.unique_id, uid);
 859                 device->flags.unique_id = 1;
 860         }
 861         if (cid_list) {
 862                 device->pnp.cid_list = kmalloc(cid_list->size, GFP_KERNEL);
 863                 if (device->pnp.cid_list)
 864                         memcpy(device->pnp.cid_list, cid_list, cid_list->size);
 865                 else
 866                         printk(KERN_ERR "Memory allocation error\n");
 867         }
 868
 869         acpi_os_free(buffer.pointer);
 870 }
 871
 872 static int acpi_device_set_context(struct acpi_device *device, int type)
 873 {
 874         acpi_status status = AE_OK;
 875         int result = 0;
 876         /*
 877          * Context
 878          * -------
 879          * Attach this 'struct acpi_device' to the ACPI object.  This makes
 880          * resolutions from handle->device very efficient.  Note that we need
 881          * to be careful with fixed-feature devices as they all attach to the
 882          * root object.
 883          */
 884         if (type != ACPI_BUS_TYPE_POWER_BUTTON &&
 885             type != ACPI_BUS_TYPE_SLEEP_BUTTON) {
 886                 status = acpi_attach_data(device->handle,
 887                                           acpi_bus_data_handler, device);
 888
 889                 if (ACPI_FAILURE(status)) {
 890                         printk("Error attaching device data\n");
 891                         result = -ENODEV;
 892                 }
 893         }
 894         return result;
 895 }
 896
 897 static void acpi_device_get_debug_info(struct acpi_device *device,
 898                                        acpi_handle handle, int type)
 899 {
 900 #ifdef CONFIG_ACPI_DEBUG_OUTPUT
 901         char *type_string = NULL;
 902         char name[80] = { '?', '\0' };
 903         struct acpi_buffer buffer = { sizeof(name), name };
 904
 905         switch (type) {
 906         case ACPI_BUS_TYPE_DEVICE:
 907                 type_string = "Device";
 908                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 909                 break;
 910         case ACPI_BUS_TYPE_POWER:
 911                 type_string = "Power Resource";
 912                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 913                 break;
 914         case ACPI_BUS_TYPE_PROCESSOR:
 915                 type_string = "Processor";
 916                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 917                 break;
 918         case ACPI_BUS_TYPE_SYSTEM:
 919                 type_string = "System";
 920                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 921                 break;
 922         case ACPI_BUS_TYPE_THERMAL:
 923                 type_string = "Thermal Zone";
 924                 acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 925                 break;
 926         case ACPI_BUS_TYPE_POWER_BUTTON:
 927                 type_string = "Power Button";
 928                 sprintf(name, "PWRB");
 929                 break;
 930         case ACPI_BUS_TYPE_SLEEP_BUTTON:
 931                 type_string = "Sleep Button";
 932                 sprintf(name, "SLPB");
 933                 break;
 934         }
 935
 936         printk(KERN_DEBUG "Found %s %s [%p]\n", type_string, name, handle);
 937 #endif                          /*CONFIG_ACPI_DEBUG_OUTPUT */
 938 }
 939
 940 static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
 941 {
 942         int result = 0;
 943         struct acpi_driver *driver;
 944
 945         ACPI_FUNCTION_TRACE("acpi_bus_remove");
 946
 947         if (!dev)
 948                 return_VALUE(-EINVAL);
 949
 950         driver = dev->driver;
 951
 952         if ((driver) && (driver->ops.remove)) {
 953
 954                 if (driver->ops.stop) {
 955                         result = driver->ops.stop(dev, ACPI_BUS_REMOVAL_EJECT);
 956                         if (result)
 957                                 return_VALUE(result);
 958                 }
 959
 960                 result = dev->driver->ops.remove(dev, ACPI_BUS_REMOVAL_EJECT);
 961                 if (result) {
 962                         return_VALUE(result);
 963                 }
 964
 965                 atomic_dec(&dev->driver->references);
 966                 dev->driver = NULL;
 967                 acpi_driver_data(dev) = NULL;
 968         }
 969
 970         if (!rmdevice)
 971                 return_VALUE(0);
 972
 973         if (dev->flags.bus_address) {
 974                 if ((dev->parent) && (dev->parent->ops.unbind))
 975                         dev->parent->ops.unbind(dev);
 976         }
 977
 978         acpi_device_unregister(dev, ACPI_BUS_REMOVAL_EJECT);
 979
 980         return_VALUE(0);
 981 }
 982
 983 static int
 984 acpi_add_single_object(struct acpi_device **child,
 985                        struct acpi_device *parent, acpi_handle handle, int type)
 986 {
 987         int result = 0;
 988         struct acpi_device *device = NULL;
 989
 990         ACPI_FUNCTION_TRACE("acpi_add_single_object");
 991
 992         if (!child)
 993                 return_VALUE(-EINVAL);
 994
 995         device = kmalloc(sizeof(struct acpi_device), GFP_KERNEL);
 996         if (!device) {
 997                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Memory allocation error\n"));
 998                 return_VALUE(-ENOMEM);
 999         }
1000         memset(device, 0, sizeof(struct acpi_device));
1001
1002         device->handle = handle;
1003         device->parent = parent;
1004
1005         acpi_device_get_busid(device, handle, type);
1006
1007         /*
1008          * Flags
1009          * -----
1010          * Get prior to calling acpi_bus_get_status() so we know whether
1011          * or not _STA is present.  Note that we only look for object
1012          * handles -- cannot evaluate objects until we know the device is
1013          * present and properly initialized.
1014          */
1015         result = acpi_bus_get_flags(device);
1016         if (result)
1017                 goto end;
1018
1019         /*
1020          * Status
1021          * ------
1022          * See if the device is present.  We always assume that non-Device
1023          * and non-Processor objects (e.g. thermal zones, power resources,
1024          * etc.) are present, functioning, etc. (at least when parent object
1025          * is present).  Note that _STA has a different meaning for some
1026          * objects (e.g. power resources) so we need to be careful how we use
1027          * it.
1028          */
1029         switch (type) {
1030         case ACPI_BUS_TYPE_PROCESSOR:
1031         case ACPI_BUS_TYPE_DEVICE:
1032                 result = acpi_bus_get_status(device);
1033                 if (ACPI_FAILURE(result) || !device->status.present) {
1034                         result = -ENOENT;
1035                         goto end;
1036                 }
1037                 break;
1038         default:
1039                 STRUCT_TO_INT(device->status) = 0x0F;
1040                 break;
1041         }
1042
1043         /*
1044          * Initialize Device
1045          * -----------------
1046          * TBD: Synch with Core's enumeration/initialization process.
1047          */
1048
1049         /*
1050          * Hardware ID, Unique ID, & Bus Address
1051          * -------------------------------------
1052          */
1053         acpi_device_set_id(device, parent, handle, type);
1054
1055         /*
1056          * Power Management
1057          * ----------------
1058          */
1059         if (device->flags.power_manageable) {
1060                 result = acpi_bus_get_power_flags(device);
1061                 if (result)
1062                         goto end;
1063         }
1064
1065         /*
1066          * Wakeup device management
1067          *-----------------------
1068          */
1069         if (device->flags.wake_capable) {
1070                 result = acpi_bus_get_wakeup_device_flags(device);
1071                 if (result)
1072                         goto end;
1073         }
1074
1075         /*
1076          * Performance Management
1077          * ----------------------
1078          */
1079         if (device->flags.performance_manageable) {
1080                 result = acpi_bus_get_perf_flags(device);
1081                 if (result)
1082                         goto end;
1083         }
1084
1085         if ((result = acpi_device_set_context(device, type)))
1086                 goto end;
1087
1088         acpi_device_get_debug_info(device, handle, type);
1089
1090         acpi_device_register(device, parent);
1091
1092         /*
1093          * Bind _ADR-Based Devices
1094          * -----------------------
1095          * If there's a a bus address (_ADR) then we utilize the parent's
1096          * 'bind' function (if exists) to bind the ACPI- and natively-
1097          * enumerated device representations.
1098          */
1099         if (device->flags.bus_address) {
1100                 if (device->parent && device->parent->ops.bind)
1101                         device->parent->ops.bind(device);
1102         }
1103
1104         /*
1105          * Locate & Attach Driver
1106          * ----------------------
1107          * If there's a hardware id (_HID) or compatible ids (_CID) we check
1108          * to see if there's a driver installed for this kind of device.  Note
1109          * that drivers can install before or after a device is enumerated.
1110          *
1111          * TBD: Assumes LDM provides driver hot-plug capability.
1112          */
1113         acpi_bus_find_driver(device);
1114
1115       end:
1116         if (!result)
1117                 *child = device;
1118         else {
1119                 kfree(device->pnp.cid_list);
1120                 kfree(device);
1121         }
1122
1123         return_VALUE(result);
1124 }
1125
1126 static int acpi_bus_scan(struct acpi_device *start, struct acpi_bus_ops *ops)
1127 {
1128         acpi_status status = AE_OK;
1129         struct acpi_device *parent = NULL;
1130         struct acpi_device *child = NULL;
1131         acpi_handle phandle = NULL;
1132         acpi_handle chandle = NULL;
1133         acpi_object_type type = 0;
1134         u32 level = 1;
1135
1136         ACPI_FUNCTION_TRACE("acpi_bus_scan");
1137
1138         if (!start)
1139                 return_VALUE(-EINVAL);
1140
1141         parent = start;
1142         phandle = start->handle;
1143
1144         /*
1145          * Parse through the ACPI namespace, identify all 'devices', and
1146          * create a new 'struct acpi_device' for each.
1147          */
1148         while ((level > 0) && parent) {
1149
1150                 status = acpi_get_next_object(ACPI_TYPE_ANY, phandle,
1151                                               chandle, &chandle);
1152
1153                 /*
1154                  * If this scope is exhausted then move our way back up.
1155                  */
1156                 if (ACPI_FAILURE(status)) {
1157                         level--;
1158                         chandle = phandle;
1159                         acpi_get_parent(phandle, &phandle);
1160                         if (parent->parent)
1161                                 parent = parent->parent;
1162                         continue;
1163                 }
1164
1165                 status = acpi_get_type(chandle, &type);
1166                 if (ACPI_FAILURE(status))
1167                         continue;
1168
1169                 /*
1170                  * If this is a scope object then parse it (depth-first).
1171                  */
1172                 if (type == ACPI_TYPE_LOCAL_SCOPE) {
1173                         level++;
1174                         phandle = chandle;
1175                         chandle = NULL;
1176                         continue;
1177                 }
1178
1179                 /*
1180                  * We're only interested in objects that we consider 'devices'.
1181                  */
1182                 switch (type) {
1183                 case ACPI_TYPE_DEVICE:
1184                         type = ACPI_BUS_TYPE_DEVICE;
1185                         break;
1186                 case ACPI_TYPE_PROCESSOR:
1187                         type = ACPI_BUS_TYPE_PROCESSOR;
1188                         break;
1189                 case ACPI_TYPE_THERMAL:
1190                         type = ACPI_BUS_TYPE_THERMAL;
1191                         break;
1192                 case ACPI_TYPE_POWER:
1193                         type = ACPI_BUS_TYPE_POWER;
1194                         break;
1195                 default:
1196                         continue;
1197                 }
1198
1199                 if (ops->acpi_op_add)
1200                         status = acpi_add_single_object(&child, parent,
1201                                                         chandle, type);
1202                 else
1203                         status = acpi_bus_get_device(chandle, &child);
1204
1205                 if (ACPI_FAILURE(status))
1206                         continue;
1207
1208                 if (ops->acpi_op_start) {
1209                         status = acpi_start_single_object(child);
1210                         if (ACPI_FAILURE(status))
1211                                 continue;
1212                 }
1213
1214                 /*
1215                  * If the device is present, enabled, and functioning then
1216                  * parse its scope (depth-first).  Note that we need to
1217                  * represent absent devices to facilitate PnP notifications
1218                  * -- but only the subtree head (not all of its children,
1219                  * which will be enumerated when the parent is inserted).
1220                  *
1221                  * TBD: Need notifications and other detection mechanisms
1222                  *      in place before we can fully implement this.
1223                  */
1224                 if (child->status.present) {
1225                         status = acpi_get_next_object(ACPI_TYPE_ANY, chandle,
1226                                                       NULL, NULL);
1227                         if (ACPI_SUCCESS(status)) {
1228                                 level++;
1229                                 phandle = chandle;
1230                                 chandle = NULL;
1231                                 parent = child;
1232                         }
1233                 }
1234         }
1235
1236         return_VALUE(0);
1237 }
1238
1239 int
1240 acpi_bus_add(struct acpi_device **child,
1241              struct acpi_device *parent, acpi_handle handle, int type)
1242 {
1243         int result;
1244         struct acpi_bus_ops ops;
1245
1246         ACPI_FUNCTION_TRACE("acpi_bus_add");
1247
1248         result = acpi_add_single_object(child, parent, handle, type);
1249         if (!result) {
1250                 memset(&ops, 0, sizeof(ops));
1251                 ops.acpi_op_add = 1;
1252                 result = acpi_bus_scan(*child, &ops);
1253         }
1254         return_VALUE(result);
1255 }
1256
1257 EXPORT_SYMBOL(acpi_bus_add);
1258
1259 int acpi_bus_start(struct acpi_device *device)
1260 {
1261         int result;
1262         struct acpi_bus_ops ops;
1263
1264         ACPI_FUNCTION_TRACE("acpi_bus_start");
1265
1266         if (!device)
1267                 return_VALUE(-EINVAL);
1268
1269         result = acpi_start_single_object(device);
1270         if (!result) {
1271                 memset(&ops, 0, sizeof(ops));
1272                 ops.acpi_op_start = 1;
1273                 result = acpi_bus_scan(device, &ops);
1274         }
1275         return_VALUE(result);
1276 }
1277
1278 EXPORT_SYMBOL(acpi_bus_start);
1279
1280 static int acpi_bus_trim(struct acpi_device *start, int rmdevice)
1281 {
1282         acpi_status status;
1283         struct acpi_device *parent, *child;
1284         acpi_handle phandle, chandle;
1285         acpi_object_type type;
1286         u32 level = 1;
1287         int err = 0;
1288
1289         parent = start;
1290         phandle = start->handle;
1291         child = chandle = NULL;
1292
1293         while ((level > 0) && parent && (!err)) {
1294                 status = acpi_get_next_object(ACPI_TYPE_ANY, phandle,
1295                                               chandle, &chandle);
1296
1297                 /*
1298                  * If this scope is exhausted then move our way back up.
1299                  */
1300                 if (ACPI_FAILURE(status)) {
1301                         level--;
1302                         chandle = phandle;
1303                         acpi_get_parent(phandle, &phandle);
1304                         child = parent;
1305                         parent = parent->parent;
1306
1307                         if (level == 0)
1308                                 err = acpi_bus_remove(child, rmdevice);
1309                         else
1310                                 err = acpi_bus_remove(child, 1);
1311
1312                         continue;
1313                 }
1314
1315                 status = acpi_get_type(chandle, &type);
1316                 if (ACPI_FAILURE(status)) {
1317                         continue;
1318                 }
1319                 /*
1320                  * If there is a device corresponding to chandle then
1321                  * parse it (depth-first).
1322                  */
1323                 if (acpi_bus_get_device(chandle, &child) == 0) {
1324                         level++;
1325                         phandle = chandle;
1326                         chandle = NULL;
1327                         parent = child;
1328                 }
1329                 continue;
1330         }
1331         return err;
1332 }
1333
1334 static int acpi_bus_scan_fixed(struct acpi_device *root)
1335 {
1336         int result = 0;
1337         struct acpi_device *device = NULL;
1338
1339         ACPI_FUNCTION_TRACE("acpi_bus_scan_fixed");
1340
1341         if (!root)
1342                 return_VALUE(-ENODEV);
1343
1344         /*
1345          * Enumerate all fixed-feature devices.
1346          */
1347         if (acpi_fadt.pwr_button == 0) {
1348                 result = acpi_add_single_object(&device, acpi_root,
1349                                                 NULL,
1350                                                 ACPI_BUS_TYPE_POWER_BUTTON);
1351                 if (!result)
1352                         result = acpi_start_single_object(device);
1353         }
1354
1355         if (acpi_fadt.sleep_button == 0) {
1356                 result = acpi_add_single_object(&device, acpi_root,
1357                                                 NULL,
1358                                                 ACPI_BUS_TYPE_SLEEP_BUTTON);
1359                 if (!result)
1360                         result = acpi_start_single_object(device);
1361         }
1362
1363         return_VALUE(result);
1364 }
1365
1366 static int __init acpi_scan_init(void)
1367 {
1368         int result;
1369         struct acpi_bus_ops ops;
1370
1371         ACPI_FUNCTION_TRACE("acpi_scan_init");
1372
1373         if (acpi_disabled)
1374                 return_VALUE(0);
1375
1376         kset_register(&acpi_namespace_kset);
1377
1378         /*
1379          * Create the root device in the bus's device tree
1380          */
1381         result = acpi_add_single_object(&acpi_root, NULL, ACPI_ROOT_OBJECT,
1382                                         ACPI_BUS_TYPE_SYSTEM);
1383         if (result)
1384                 goto Done;
1385
1386         result = acpi_start_single_object(acpi_root);
1387
1388         /*
1389          * Enumerate devices in the ACPI namespace.
1390          */
1391         result = acpi_bus_scan_fixed(acpi_root);
1392         if (!result) {
1393                 memset(&ops, 0, sizeof(ops));
1394                 ops.acpi_op_add = 1;
1395                 ops.acpi_op_start = 1;
1396                 result = acpi_bus_scan(acpi_root, &ops);
1397         }
1398
1399         if (result)
1400                 acpi_device_unregister(acpi_root, ACPI_BUS_REMOVAL_NORMAL);
1401
1402       Done:
1403         return_VALUE(result);
1404 }
1405
1406 subsys_initcall(acpi_scan_init);