xref: /linux/drivers/acpi/scan.c (revision 2624f124b3b5d550ab2fbef7ee3bc0e1fed09722)
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 	if (dev->pnp.cid_list)
32 		kfree(dev->pnp.cid_list);
33 	kfree(dev);
34 }
35 
36 struct acpi_device_attribute {
37 	struct attribute attr;
38 	 ssize_t(*show) (struct acpi_device *, char *);
39 	 ssize_t(*store) (struct acpi_device *, const char *, size_t);
40 };
41 
42 typedef void acpi_device_sysfs_files(struct kobject *,
43 				     const struct attribute *);
44 
45 static void setup_sys_fs_device_files(struct acpi_device *dev,
46 				      acpi_device_sysfs_files * func);
47 
48 #define create_sysfs_device_files(dev)	\
49 	setup_sys_fs_device_files(dev, (acpi_device_sysfs_files *)&sysfs_create_file)
50 #define remove_sysfs_device_files(dev)	\
51 	setup_sys_fs_device_files(dev, (acpi_device_sysfs_files *)&sysfs_remove_file)
52 
53 #define to_acpi_device(n) container_of(n, struct acpi_device, kobj)
54 #define to_handle_attr(n) container_of(n, struct acpi_device_attribute, attr);
55 
56 static ssize_t acpi_device_attr_show(struct kobject *kobj,
57 				     struct attribute *attr, char *buf)
58 {
59 	struct acpi_device *device = to_acpi_device(kobj);
60 	struct acpi_device_attribute *attribute = to_handle_attr(attr);
61 	return attribute->show ? attribute->show(device, buf) : -EIO;
62 }
63 static ssize_t acpi_device_attr_store(struct kobject *kobj,
64 				      struct attribute *attr, const char *buf,
65 				      size_t len)
66 {
67 	struct acpi_device *device = to_acpi_device(kobj);
68 	struct acpi_device_attribute *attribute = to_handle_attr(attr);
69 	return attribute->store ? attribute->store(device, buf, len) : -EIO;
70 }
71 
72 static struct sysfs_ops acpi_device_sysfs_ops = {
73 	.show = acpi_device_attr_show,
74 	.store = acpi_device_attr_store,
75 };
76 
77 static struct kobj_type ktype_acpi_ns = {
78 	.sysfs_ops = &acpi_device_sysfs_ops,
79 	.release = acpi_device_release,
80 };
81 
82 static int namespace_hotplug(struct kset *kset, struct kobject *kobj,
83 			     char **envp, int num_envp, char *buffer,
84 			     int buffer_size)
85 {
86 	struct acpi_device *dev = to_acpi_device(kobj);
87 	int i = 0;
88 	int len = 0;
89 
90 	if (!dev->driver)
91 		return 0;
92 
93 	if (add_hotplug_env_var(envp, num_envp, &i, buffer, buffer_size, &len,
94 				"PHYSDEVDRIVER=%s", dev->driver->name))
95 		return -ENOMEM;
96 
97 	envp[i] = NULL;
98 
99 	return 0;
100 }
101 
102 static struct kset_hotplug_ops namespace_hotplug_ops = {
103 	.hotplug = &namespace_hotplug,
104 };
105 
106 static struct kset acpi_namespace_kset = {
107 	.kobj = {
108 		 .name = "namespace",
109 		 },
110 	.subsys = &acpi_subsys,
111 	.ktype = &ktype_acpi_ns,
112 	.hotplug_ops = &namespace_hotplug_ops,
113 };
114 
115 static void acpi_device_register(struct acpi_device *device,
116 				 struct acpi_device *parent)
117 {
118 	/*
119 	 * Linkage
120 	 * -------
121 	 * Link this device to its parent and siblings.
122 	 */
123 	INIT_LIST_HEAD(&device->children);
124 	INIT_LIST_HEAD(&device->node);
125 	INIT_LIST_HEAD(&device->g_list);
126 	INIT_LIST_HEAD(&device->wakeup_list);
127 
128 	spin_lock(&acpi_device_lock);
129 	if (device->parent) {
130 		list_add_tail(&device->node, &device->parent->children);
131 		list_add_tail(&device->g_list, &device->parent->g_list);
132 	} else
133 		list_add_tail(&device->g_list, &acpi_device_list);
134 	if (device->wakeup.flags.valid)
135 		list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);
136 	spin_unlock(&acpi_device_lock);
137 
138 	strlcpy(device->kobj.name, device->pnp.bus_id, KOBJ_NAME_LEN);
139 	if (parent)
140 		device->kobj.parent = &parent->kobj;
141 	device->kobj.ktype = &ktype_acpi_ns;
142 	device->kobj.kset = &acpi_namespace_kset;
143 	kobject_register(&device->kobj);
144 	create_sysfs_device_files(device);
145 }
146 
147 static int acpi_device_unregister(struct acpi_device *device, int type)
148 {
149 	spin_lock(&acpi_device_lock);
150 	if (device->parent) {
151 		list_del(&device->node);
152 		list_del(&device->g_list);
153 	} else
154 		list_del(&device->g_list);
155 
156 	list_del(&device->wakeup_list);
157 
158 	spin_unlock(&acpi_device_lock);
159 
160 	acpi_detach_data(device->handle, acpi_bus_data_handler);
161 	remove_sysfs_device_files(device);
162 	kobject_unregister(&device->kobj);
163 	return 0;
164 }
165 
166 void acpi_bus_data_handler(acpi_handle handle, u32 function, void *context)
167 {
168 	ACPI_FUNCTION_TRACE("acpi_bus_data_handler");
169 
170 	/* TBD */
171 
172 	return_VOID;
173 }
174 
175 static int acpi_bus_get_power_flags(struct acpi_device *device)
176 {
177 	acpi_status status = 0;
178 	acpi_handle handle = NULL;
179 	u32 i = 0;
180 
181 	ACPI_FUNCTION_TRACE("acpi_bus_get_power_flags");
182 
183 	/*
184 	 * Power Management Flags
185 	 */
186 	status = acpi_get_handle(device->handle, "_PSC", &handle);
187 	if (ACPI_SUCCESS(status))
188 		device->power.flags.explicit_get = 1;
189 	status = acpi_get_handle(device->handle, "_IRC", &handle);
190 	if (ACPI_SUCCESS(status))
191 		device->power.flags.inrush_current = 1;
192 
193 	/*
194 	 * Enumerate supported power management states
195 	 */
196 	for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3; i++) {
197 		struct acpi_device_power_state *ps = &device->power.states[i];
198 		char object_name[5] = { '_', 'P', 'R', '0' + i, '\0' };
199 
200 		/* Evaluate "_PRx" to se if power resources are referenced */
201 		acpi_evaluate_reference(device->handle, object_name, NULL,
202 					&ps->resources);
203 		if (ps->resources.count) {
204 			device->power.flags.power_resources = 1;
205 			ps->flags.valid = 1;
206 		}
207 
208 		/* Evaluate "_PSx" to see if we can do explicit sets */
209 		object_name[2] = 'S';
210 		status = acpi_get_handle(device->handle, object_name, &handle);
211 		if (ACPI_SUCCESS(status)) {
212 			ps->flags.explicit_set = 1;
213 			ps->flags.valid = 1;
214 		}
215 
216 		/* State is valid if we have some power control */
217 		if (ps->resources.count || ps->flags.explicit_set)
218 			ps->flags.valid = 1;
219 
220 		ps->power = -1;	/* Unknown - driver assigned */
221 		ps->latency = -1;	/* Unknown - driver assigned */
222 	}
223 
224 	/* Set defaults for D0 and D3 states (always valid) */
225 	device->power.states[ACPI_STATE_D0].flags.valid = 1;
226 	device->power.states[ACPI_STATE_D0].power = 100;
227 	device->power.states[ACPI_STATE_D3].flags.valid = 1;
228 	device->power.states[ACPI_STATE_D3].power = 0;
229 
230 	/* TBD: System wake support and resource requirements. */
231 
232 	device->power.state = ACPI_STATE_UNKNOWN;
233 
234 	return_VALUE(0);
235 }
236 
237 int acpi_match_ids(struct acpi_device *device, char *ids)
238 {
239 	int error = 0;
240 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
241 
242 	if (device->flags.hardware_id)
243 		if (strstr(ids, device->pnp.hardware_id))
244 			goto Done;
245 
246 	if (device->flags.compatible_ids) {
247 		struct acpi_compatible_id_list *cid_list = device->pnp.cid_list;
248 		int i;
249 
250 		/* compare multiple _CID entries against driver ids */
251 		for (i = 0; i < cid_list->count; i++) {
252 			if (strstr(ids, cid_list->id[i].value))
253 				goto Done;
254 		}
255 	}
256 	error = -ENOENT;
257 
258       Done:
259 	if (buffer.pointer)
260 		acpi_os_free(buffer.pointer);
261 	return error;
262 }
263 
264 static acpi_status
265 acpi_bus_extract_wakeup_device_power_package(struct acpi_device *device,
266 					     union acpi_object *package)
267 {
268 	int i = 0;
269 	union acpi_object *element = NULL;
270 
271 	if (!device || !package || (package->package.count < 2))
272 		return AE_BAD_PARAMETER;
273 
274 	element = &(package->package.elements[0]);
275 	if (!element)
276 		return AE_BAD_PARAMETER;
277 	if (element->type == ACPI_TYPE_PACKAGE) {
278 		if ((element->package.count < 2) ||
279 		    (element->package.elements[0].type !=
280 		     ACPI_TYPE_LOCAL_REFERENCE)
281 		    || (element->package.elements[1].type != ACPI_TYPE_INTEGER))
282 			return AE_BAD_DATA;
283 		device->wakeup.gpe_device =
284 		    element->package.elements[0].reference.handle;
285 		device->wakeup.gpe_number =
286 		    (u32) element->package.elements[1].integer.value;
287 	} else if (element->type == ACPI_TYPE_INTEGER) {
288 		device->wakeup.gpe_number = element->integer.value;
289 	} else
290 		return AE_BAD_DATA;
291 
292 	element = &(package->package.elements[1]);
293 	if (element->type != ACPI_TYPE_INTEGER) {
294 		return AE_BAD_DATA;
295 	}
296 	device->wakeup.sleep_state = element->integer.value;
297 
298 	if ((package->package.count - 2) > ACPI_MAX_HANDLES) {
299 		return AE_NO_MEMORY;
300 	}
301 	device->wakeup.resources.count = package->package.count - 2;
302 	for (i = 0; i < device->wakeup.resources.count; i++) {
303 		element = &(package->package.elements[i + 2]);
304 		if (element->type != ACPI_TYPE_ANY) {
305 			return AE_BAD_DATA;
306 		}
307 
308 		device->wakeup.resources.handles[i] = element->reference.handle;
309 	}
310 
311 	return AE_OK;
312 }
313 
314 static int acpi_bus_get_wakeup_device_flags(struct acpi_device *device)
315 {
316 	acpi_status status = 0;
317 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
318 	union acpi_object *package = NULL;
319 
320 	ACPI_FUNCTION_TRACE("acpi_bus_get_wakeup_flags");
321 
322 	/* _PRW */
323 	status = acpi_evaluate_object(device->handle, "_PRW", NULL, &buffer);
324 	if (ACPI_FAILURE(status)) {
325 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error evaluating _PRW\n"));
326 		goto end;
327 	}
328 
329 	package = (union acpi_object *)buffer.pointer;
330 	status = acpi_bus_extract_wakeup_device_power_package(device, package);
331 	if (ACPI_FAILURE(status)) {
332 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
333 				  "Error extracting _PRW package\n"));
334 		goto end;
335 	}
336 
337 	acpi_os_free(buffer.pointer);
338 
339 	device->wakeup.flags.valid = 1;
340 	/* Power button, Lid switch always enable wakeup */
341 	if (!acpi_match_ids(device, "PNP0C0D,PNP0C0C,PNP0C0E"))
342 		device->wakeup.flags.run_wake = 1;
343 
344       end:
345 	if (ACPI_FAILURE(status))
346 		device->flags.wake_capable = 0;
347 	return_VALUE(0);
348 }
349 
350 /* --------------------------------------------------------------------------
351 		ACPI hotplug sysfs device file support
352    -------------------------------------------------------------------------- */
353 static ssize_t acpi_eject_store(struct acpi_device *device,
354 				const char *buf, size_t count);
355 
356 #define ACPI_DEVICE_ATTR(_name,_mode,_show,_store) \
357 static struct acpi_device_attribute acpi_device_attr_##_name = \
358 		__ATTR(_name, _mode, _show, _store)
359 
360 ACPI_DEVICE_ATTR(eject, 0200, NULL, acpi_eject_store);
361 
362 /**
363  * setup_sys_fs_device_files - sets up the device files under device namespace
364  * @dev:	acpi_device object
365  * @func:	function pointer to create or destroy the device file
366  */
367 static void
368 setup_sys_fs_device_files(struct acpi_device *dev,
369 			  acpi_device_sysfs_files * func)
370 {
371 	acpi_status status;
372 	acpi_handle temp = NULL;
373 
374 	/*
375 	 * If device has _EJ0, 'eject' file is created that is used to trigger
376 	 * hot-removal function from userland.
377 	 */
378 	status = acpi_get_handle(dev->handle, "_EJ0", &temp);
379 	if (ACPI_SUCCESS(status))
380 		(*(func)) (&dev->kobj, &acpi_device_attr_eject.attr);
381 }
382 
383 static int acpi_eject_operation(acpi_handle handle, int lockable)
384 {
385 	struct acpi_object_list arg_list;
386 	union acpi_object arg;
387 	acpi_status status = AE_OK;
388 
389 	/*
390 	 * TBD: evaluate _PS3?
391 	 */
392 
393 	if (lockable) {
394 		arg_list.count = 1;
395 		arg_list.pointer = &arg;
396 		arg.type = ACPI_TYPE_INTEGER;
397 		arg.integer.value = 0;
398 		acpi_evaluate_object(handle, "_LCK", &arg_list, NULL);
399 	}
400 
401 	arg_list.count = 1;
402 	arg_list.pointer = &arg;
403 	arg.type = ACPI_TYPE_INTEGER;
404 	arg.integer.value = 1;
405 
406 	/*
407 	 * TBD: _EJD support.
408 	 */
409 
410 	status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL);
411 	if (ACPI_FAILURE(status)) {
412 		return (-ENODEV);
413 	}
414 
415 	return (0);
416 }
417 
418 static ssize_t
419 acpi_eject_store(struct acpi_device *device, const char *buf, size_t count)
420 {
421 	int result;
422 	int ret = count;
423 	int islockable;
424 	acpi_status status;
425 	acpi_handle handle;
426 	acpi_object_type type = 0;
427 
428 	if ((!count) || (buf[0] != '1')) {
429 		return -EINVAL;
430 	}
431 #ifndef FORCE_EJECT
432 	if (device->driver == NULL) {
433 		ret = -ENODEV;
434 		goto err;
435 	}
436 #endif
437 	status = acpi_get_type(device->handle, &type);
438 	if (ACPI_FAILURE(status) || (!device->flags.ejectable)) {
439 		ret = -ENODEV;
440 		goto err;
441 	}
442 
443 	islockable = device->flags.lockable;
444 	handle = device->handle;
445 
446 	if (type == ACPI_TYPE_PROCESSOR)
447 		result = acpi_bus_trim(device, 0);
448 	else
449 		result = acpi_bus_trim(device, 1);
450 
451 	if (!result)
452 		result = acpi_eject_operation(handle, islockable);
453 
454 	if (result) {
455 		ret = -EBUSY;
456 	}
457       err:
458 	return ret;
459 }
460 
461 /* --------------------------------------------------------------------------
462                               Performance Management
463    -------------------------------------------------------------------------- */
464 
465 static int acpi_bus_get_perf_flags(struct acpi_device *device)
466 {
467 	device->performance.state = ACPI_STATE_UNKNOWN;
468 	return 0;
469 }
470 
471 /* --------------------------------------------------------------------------
472                                  Driver Management
473    -------------------------------------------------------------------------- */
474 
475 static LIST_HEAD(acpi_bus_drivers);
476 static DECLARE_MUTEX(acpi_bus_drivers_lock);
477 
478 /**
479  * acpi_bus_match
480  * --------------
481  * Checks the device's hardware (_HID) or compatible (_CID) ids to see if it
482  * matches the specified driver's criteria.
483  */
484 static int
485 acpi_bus_match(struct acpi_device *device, struct acpi_driver *driver)
486 {
487 	if (driver && driver->ops.match)
488 		return driver->ops.match(device, driver);
489 	return acpi_match_ids(device, driver->ids);
490 }
491 
492 /**
493  * acpi_bus_driver_init
494  * --------------------
495  * Used to initialize a device via its device driver.  Called whenever a
496  * driver is bound to a device.  Invokes the driver's add() and start() ops.
497  */
498 static int
499 acpi_bus_driver_init(struct acpi_device *device, struct acpi_driver *driver)
500 {
501 	int result = 0;
502 
503 	ACPI_FUNCTION_TRACE("acpi_bus_driver_init");
504 
505 	if (!device || !driver)
506 		return_VALUE(-EINVAL);
507 
508 	if (!driver->ops.add)
509 		return_VALUE(-ENOSYS);
510 
511 	result = driver->ops.add(device);
512 	if (result) {
513 		device->driver = NULL;
514 		acpi_driver_data(device) = NULL;
515 		return_VALUE(result);
516 	}
517 
518 	device->driver = driver;
519 
520 	/*
521 	 * TBD - Configuration Management: Assign resources to device based
522 	 * upon possible configuration and currently allocated resources.
523 	 */
524 
525 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
526 			  "Driver successfully bound to device\n"));
527 	return_VALUE(0);
528 }
529 
530 static int acpi_start_single_object(struct acpi_device *device)
531 {
532 	int result = 0;
533 	struct acpi_driver *driver;
534 
535 	ACPI_FUNCTION_TRACE("acpi_start_single_object");
536 
537 	if (!(driver = device->driver))
538 		return_VALUE(0);
539 
540 	if (driver->ops.start) {
541 		result = driver->ops.start(device);
542 		if (result && driver->ops.remove)
543 			driver->ops.remove(device, ACPI_BUS_REMOVAL_NORMAL);
544 	}
545 
546 	return_VALUE(result);
547 }
548 
549 static int acpi_driver_attach(struct acpi_driver *drv)
550 {
551 	struct list_head *node, *next;
552 	int count = 0;
553 
554 	ACPI_FUNCTION_TRACE("acpi_driver_attach");
555 
556 	spin_lock(&acpi_device_lock);
557 	list_for_each_safe(node, next, &acpi_device_list) {
558 		struct acpi_device *dev =
559 		    container_of(node, struct acpi_device, g_list);
560 
561 		if (dev->driver || !dev->status.present)
562 			continue;
563 		spin_unlock(&acpi_device_lock);
564 
565 		if (!acpi_bus_match(dev, drv)) {
566 			if (!acpi_bus_driver_init(dev, drv)) {
567 				acpi_start_single_object(dev);
568 				atomic_inc(&drv->references);
569 				count++;
570 				ACPI_DEBUG_PRINT((ACPI_DB_INFO,
571 						  "Found driver [%s] for device [%s]\n",
572 						  drv->name, dev->pnp.bus_id));
573 			}
574 		}
575 		spin_lock(&acpi_device_lock);
576 	}
577 	spin_unlock(&acpi_device_lock);
578 	return_VALUE(count);
579 }
580 
581 static int acpi_driver_detach(struct acpi_driver *drv)
582 {
583 	struct list_head *node, *next;
584 
585 	ACPI_FUNCTION_TRACE("acpi_driver_detach");
586 
587 	spin_lock(&acpi_device_lock);
588 	list_for_each_safe(node, next, &acpi_device_list) {
589 		struct acpi_device *dev =
590 		    container_of(node, struct acpi_device, g_list);
591 
592 		if (dev->driver == drv) {
593 			spin_unlock(&acpi_device_lock);
594 			if (drv->ops.remove)
595 				drv->ops.remove(dev, ACPI_BUS_REMOVAL_NORMAL);
596 			spin_lock(&acpi_device_lock);
597 			dev->driver = NULL;
598 			dev->driver_data = NULL;
599 			atomic_dec(&drv->references);
600 		}
601 	}
602 	spin_unlock(&acpi_device_lock);
603 	return_VALUE(0);
604 }
605 
606 /**
607  * acpi_bus_register_driver
608  * ------------------------
609  * Registers a driver with the ACPI bus.  Searches the namespace for all
610  * devices that match the driver's criteria and binds.  Returns the
611  * number of devices that were claimed by the driver, or a negative
612  * error status for failure.
613  */
614 int acpi_bus_register_driver(struct acpi_driver *driver)
615 {
616 	int count;
617 
618 	ACPI_FUNCTION_TRACE("acpi_bus_register_driver");
619 
620 	if (acpi_disabled)
621 		return_VALUE(-ENODEV);
622 
623 	if (!driver)
624 		return_VALUE(-EINVAL);
625 
626 	spin_lock(&acpi_device_lock);
627 	list_add_tail(&driver->node, &acpi_bus_drivers);
628 	spin_unlock(&acpi_device_lock);
629 	count = acpi_driver_attach(driver);
630 
631 	return_VALUE(count);
632 }
633 
634 EXPORT_SYMBOL(acpi_bus_register_driver);
635 
636 /**
637  * acpi_bus_unregister_driver
638  * --------------------------
639  * Unregisters a driver with the ACPI bus.  Searches the namespace for all
640  * devices that match the driver's criteria and unbinds.
641  */
642 int acpi_bus_unregister_driver(struct acpi_driver *driver)
643 {
644 	int error = 0;
645 
646 	ACPI_FUNCTION_TRACE("acpi_bus_unregister_driver");
647 
648 	if (driver) {
649 		acpi_driver_detach(driver);
650 
651 		if (!atomic_read(&driver->references)) {
652 			spin_lock(&acpi_device_lock);
653 			list_del_init(&driver->node);
654 			spin_unlock(&acpi_device_lock);
655 		}
656 	} else
657 		error = -EINVAL;
658 	return_VALUE(error);
659 }
660 
661 EXPORT_SYMBOL(acpi_bus_unregister_driver);
662 
663 /**
664  * acpi_bus_find_driver
665  * --------------------
666  * Parses the list of registered drivers looking for a driver applicable for
667  * the specified device.
668  */
669 static int acpi_bus_find_driver(struct acpi_device *device)
670 {
671 	int result = 0;
672 	struct list_head *node, *next;
673 
674 	ACPI_FUNCTION_TRACE("acpi_bus_find_driver");
675 
676 	spin_lock(&acpi_device_lock);
677 	list_for_each_safe(node, next, &acpi_bus_drivers) {
678 		struct acpi_driver *driver =
679 		    container_of(node, struct acpi_driver, node);
680 
681 		atomic_inc(&driver->references);
682 		spin_unlock(&acpi_device_lock);
683 		if (!acpi_bus_match(device, driver)) {
684 			result = acpi_bus_driver_init(device, driver);
685 			if (!result)
686 				goto Done;
687 		}
688 		atomic_dec(&driver->references);
689 		spin_lock(&acpi_device_lock);
690 	}
691 	spin_unlock(&acpi_device_lock);
692 
693       Done:
694 	return_VALUE(result);
695 }
696 
697 /* --------------------------------------------------------------------------
698                                  Device Enumeration
699    -------------------------------------------------------------------------- */
700 
701 static int acpi_bus_get_flags(struct acpi_device *device)
702 {
703 	acpi_status status = AE_OK;
704 	acpi_handle temp = NULL;
705 
706 	ACPI_FUNCTION_TRACE("acpi_bus_get_flags");
707 
708 	/* Presence of _STA indicates 'dynamic_status' */
709 	status = acpi_get_handle(device->handle, "_STA", &temp);
710 	if (ACPI_SUCCESS(status))
711 		device->flags.dynamic_status = 1;
712 
713 	/* Presence of _CID indicates 'compatible_ids' */
714 	status = acpi_get_handle(device->handle, "_CID", &temp);
715 	if (ACPI_SUCCESS(status))
716 		device->flags.compatible_ids = 1;
717 
718 	/* Presence of _RMV indicates 'removable' */
719 	status = acpi_get_handle(device->handle, "_RMV", &temp);
720 	if (ACPI_SUCCESS(status))
721 		device->flags.removable = 1;
722 
723 	/* Presence of _EJD|_EJ0 indicates 'ejectable' */
724 	status = acpi_get_handle(device->handle, "_EJD", &temp);
725 	if (ACPI_SUCCESS(status))
726 		device->flags.ejectable = 1;
727 	else {
728 		status = acpi_get_handle(device->handle, "_EJ0", &temp);
729 		if (ACPI_SUCCESS(status))
730 			device->flags.ejectable = 1;
731 	}
732 
733 	/* Presence of _LCK indicates 'lockable' */
734 	status = acpi_get_handle(device->handle, "_LCK", &temp);
735 	if (ACPI_SUCCESS(status))
736 		device->flags.lockable = 1;
737 
738 	/* Presence of _PS0|_PR0 indicates 'power manageable' */
739 	status = acpi_get_handle(device->handle, "_PS0", &temp);
740 	if (ACPI_FAILURE(status))
741 		status = acpi_get_handle(device->handle, "_PR0", &temp);
742 	if (ACPI_SUCCESS(status))
743 		device->flags.power_manageable = 1;
744 
745 	/* Presence of _PRW indicates wake capable */
746 	status = acpi_get_handle(device->handle, "_PRW", &temp);
747 	if (ACPI_SUCCESS(status))
748 		device->flags.wake_capable = 1;
749 
750 	/* TBD: Peformance management */
751 
752 	return_VALUE(0);
753 }
754 
755 static void acpi_device_get_busid(struct acpi_device *device,
756 				  acpi_handle handle, int type)
757 {
758 	char bus_id[5] = { '?', 0 };
759 	struct acpi_buffer buffer = { sizeof(bus_id), bus_id };
760 	int i = 0;
761 
762 	/*
763 	 * Bus ID
764 	 * ------
765 	 * The device's Bus ID is simply the object name.
766 	 * TBD: Shouldn't this value be unique (within the ACPI namespace)?
767 	 */
768 	switch (type) {
769 	case ACPI_BUS_TYPE_SYSTEM:
770 		strcpy(device->pnp.bus_id, "ACPI");
771 		break;
772 	case ACPI_BUS_TYPE_POWER_BUTTON:
773 		strcpy(device->pnp.bus_id, "PWRF");
774 		break;
775 	case ACPI_BUS_TYPE_SLEEP_BUTTON:
776 		strcpy(device->pnp.bus_id, "SLPF");
777 		break;
778 	default:
779 		acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
780 		/* Clean up trailing underscores (if any) */
781 		for (i = 3; i > 1; i--) {
782 			if (bus_id[i] == '_')
783 				bus_id[i] = '\0';
784 			else
785 				break;
786 		}
787 		strcpy(device->pnp.bus_id, bus_id);
788 		break;
789 	}
790 }
791 
792 static void acpi_device_set_id(struct acpi_device *device,
793 			       struct acpi_device *parent, acpi_handle handle,
794 			       int type)
795 {
796 	struct acpi_device_info *info;
797 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
798 	char *hid = NULL;
799 	char *uid = NULL;
800 	struct acpi_compatible_id_list *cid_list = NULL;
801 	acpi_status status;
802 
803 	switch (type) {
804 	case ACPI_BUS_TYPE_DEVICE:
805 		status = acpi_get_object_info(handle, &buffer);
806 		if (ACPI_FAILURE(status)) {
807 			printk("%s: Error reading device info\n", __FUNCTION__);
808 			return;
809 		}
810 
811 		info = buffer.pointer;
812 		if (info->valid & ACPI_VALID_HID)
813 			hid = info->hardware_id.value;
814 		if (info->valid & ACPI_VALID_UID)
815 			uid = info->unique_id.value;
816 		if (info->valid & ACPI_VALID_CID)
817 			cid_list = &info->compatibility_id;
818 		if (info->valid & ACPI_VALID_ADR) {
819 			device->pnp.bus_address = info->address;
820 			device->flags.bus_address = 1;
821 		}
822 		break;
823 	case ACPI_BUS_TYPE_POWER:
824 		hid = ACPI_POWER_HID;
825 		break;
826 	case ACPI_BUS_TYPE_PROCESSOR:
827 		hid = ACPI_PROCESSOR_HID;
828 		break;
829 	case ACPI_BUS_TYPE_SYSTEM:
830 		hid = ACPI_SYSTEM_HID;
831 		break;
832 	case ACPI_BUS_TYPE_THERMAL:
833 		hid = ACPI_THERMAL_HID;
834 		break;
835 	case ACPI_BUS_TYPE_POWER_BUTTON:
836 		hid = ACPI_BUTTON_HID_POWERF;
837 		break;
838 	case ACPI_BUS_TYPE_SLEEP_BUTTON:
839 		hid = ACPI_BUTTON_HID_SLEEPF;
840 		break;
841 	}
842 
843 	/*
844 	 * \_SB
845 	 * ----
846 	 * Fix for the system root bus device -- the only root-level device.
847 	 */
848 	if ((parent == ACPI_ROOT_OBJECT) && (type == ACPI_BUS_TYPE_DEVICE)) {
849 		hid = ACPI_BUS_HID;
850 		strcpy(device->pnp.device_name, ACPI_BUS_DEVICE_NAME);
851 		strcpy(device->pnp.device_class, ACPI_BUS_CLASS);
852 	}
853 
854 	if (hid) {
855 		strcpy(device->pnp.hardware_id, hid);
856 		device->flags.hardware_id = 1;
857 	}
858 	if (uid) {
859 		strcpy(device->pnp.unique_id, uid);
860 		device->flags.unique_id = 1;
861 	}
862 	if (cid_list) {
863 		device->pnp.cid_list = kmalloc(cid_list->size, GFP_KERNEL);
864 		if (device->pnp.cid_list)
865 			memcpy(device->pnp.cid_list, cid_list, cid_list->size);
866 		else
867 			printk(KERN_ERR "Memory allocation error\n");
868 	}
869 
870 	acpi_os_free(buffer.pointer);
871 }
872 
873 static int acpi_device_set_context(struct acpi_device *device, int type)
874 {
875 	acpi_status status = AE_OK;
876 	int result = 0;
877 	/*
878 	 * Context
879 	 * -------
880 	 * Attach this 'struct acpi_device' to the ACPI object.  This makes
881 	 * resolutions from handle->device very efficient.  Note that we need
882 	 * to be careful with fixed-feature devices as they all attach to the
883 	 * root object.
884 	 */
885 	if (type != ACPI_BUS_TYPE_POWER_BUTTON &&
886 	    type != ACPI_BUS_TYPE_SLEEP_BUTTON) {
887 		status = acpi_attach_data(device->handle,
888 					  acpi_bus_data_handler, device);
889 
890 		if (ACPI_FAILURE(status)) {
891 			printk("Error attaching device data\n");
892 			result = -ENODEV;
893 		}
894 	}
895 	return result;
896 }
897 
898 static void acpi_device_get_debug_info(struct acpi_device *device,
899 				       acpi_handle handle, int type)
900 {
901 #ifdef CONFIG_ACPI_DEBUG_OUTPUT
902 	char *type_string = NULL;
903 	char name[80] = { '?', '\0' };
904 	struct acpi_buffer buffer = { sizeof(name), name };
905 
906 	switch (type) {
907 	case ACPI_BUS_TYPE_DEVICE:
908 		type_string = "Device";
909 		acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
910 		break;
911 	case ACPI_BUS_TYPE_POWER:
912 		type_string = "Power Resource";
913 		acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
914 		break;
915 	case ACPI_BUS_TYPE_PROCESSOR:
916 		type_string = "Processor";
917 		acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
918 		break;
919 	case ACPI_BUS_TYPE_SYSTEM:
920 		type_string = "System";
921 		acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
922 		break;
923 	case ACPI_BUS_TYPE_THERMAL:
924 		type_string = "Thermal Zone";
925 		acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
926 		break;
927 	case ACPI_BUS_TYPE_POWER_BUTTON:
928 		type_string = "Power Button";
929 		sprintf(name, "PWRB");
930 		break;
931 	case ACPI_BUS_TYPE_SLEEP_BUTTON:
932 		type_string = "Sleep Button";
933 		sprintf(name, "SLPB");
934 		break;
935 	}
936 
937 	printk(KERN_DEBUG "Found %s %s [%p]\n", type_string, name, handle);
938 #endif				/*CONFIG_ACPI_DEBUG_OUTPUT */
939 }
940 
941 static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
942 {
943 	int result = 0;
944 	struct acpi_driver *driver;
945 
946 	ACPI_FUNCTION_TRACE("acpi_bus_remove");
947 
948 	if (!dev)
949 		return_VALUE(-EINVAL);
950 
951 	driver = dev->driver;
952 
953 	if ((driver) && (driver->ops.remove)) {
954 
955 		if (driver->ops.stop) {
956 			result = driver->ops.stop(dev, ACPI_BUS_REMOVAL_EJECT);
957 			if (result)
958 				return_VALUE(result);
959 		}
960 
961 		result = dev->driver->ops.remove(dev, ACPI_BUS_REMOVAL_EJECT);
962 		if (result) {
963 			return_VALUE(result);
964 		}
965 
966 		atomic_dec(&dev->driver->references);
967 		dev->driver = NULL;
968 		acpi_driver_data(dev) = NULL;
969 	}
970 
971 	if (!rmdevice)
972 		return_VALUE(0);
973 
974 	if (dev->flags.bus_address) {
975 		if ((dev->parent) && (dev->parent->ops.unbind))
976 			dev->parent->ops.unbind(dev);
977 	}
978 
979 	acpi_device_unregister(dev, ACPI_BUS_REMOVAL_EJECT);
980 
981 	return_VALUE(0);
982 }
983 
984 static int
985 acpi_add_single_object(struct acpi_device **child,
986 		       struct acpi_device *parent, acpi_handle handle, int type)
987 {
988 	int result = 0;
989 	struct acpi_device *device = NULL;
990 
991 	ACPI_FUNCTION_TRACE("acpi_add_single_object");
992 
993 	if (!child)
994 		return_VALUE(-EINVAL);
995 
996 	device = kmalloc(sizeof(struct acpi_device), GFP_KERNEL);
997 	if (!device) {
998 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Memory allocation error\n"));
999 		return_VALUE(-ENOMEM);
1000 	}
1001 	memset(device, 0, sizeof(struct acpi_device));
1002 
1003 	device->handle = handle;
1004 	device->parent = parent;
1005 
1006 	acpi_device_get_busid(device, handle, type);
1007 
1008 	/*
1009 	 * Flags
1010 	 * -----
1011 	 * Get prior to calling acpi_bus_get_status() so we know whether
1012 	 * or not _STA is present.  Note that we only look for object
1013 	 * handles -- cannot evaluate objects until we know the device is
1014 	 * present and properly initialized.
1015 	 */
1016 	result = acpi_bus_get_flags(device);
1017 	if (result)
1018 		goto end;
1019 
1020 	/*
1021 	 * Status
1022 	 * ------
1023 	 * See if the device is present.  We always assume that non-Device
1024 	 * and non-Processor objects (e.g. thermal zones, power resources,
1025 	 * etc.) are present, functioning, etc. (at least when parent object
1026 	 * is present).  Note that _STA has a different meaning for some
1027 	 * objects (e.g. power resources) so we need to be careful how we use
1028 	 * it.
1029 	 */
1030 	switch (type) {
1031 	case ACPI_BUS_TYPE_PROCESSOR:
1032 	case ACPI_BUS_TYPE_DEVICE:
1033 		result = acpi_bus_get_status(device);
1034 		if (ACPI_FAILURE(result) || !device->status.present) {
1035 			result = -ENOENT;
1036 			goto end;
1037 		}
1038 		break;
1039 	default:
1040 		STRUCT_TO_INT(device->status) = 0x0F;
1041 		break;
1042 	}
1043 
1044 	/*
1045 	 * Initialize Device
1046 	 * -----------------
1047 	 * TBD: Synch with Core's enumeration/initialization process.
1048 	 */
1049 
1050 	/*
1051 	 * Hardware ID, Unique ID, & Bus Address
1052 	 * -------------------------------------
1053 	 */
1054 	acpi_device_set_id(device, parent, handle, type);
1055 
1056 	/*
1057 	 * Power Management
1058 	 * ----------------
1059 	 */
1060 	if (device->flags.power_manageable) {
1061 		result = acpi_bus_get_power_flags(device);
1062 		if (result)
1063 			goto end;
1064 	}
1065 
1066 	/*
1067 	 * Wakeup device management
1068 	 *-----------------------
1069 	 */
1070 	if (device->flags.wake_capable) {
1071 		result = acpi_bus_get_wakeup_device_flags(device);
1072 		if (result)
1073 			goto end;
1074 	}
1075 
1076 	/*
1077 	 * Performance Management
1078 	 * ----------------------
1079 	 */
1080 	if (device->flags.performance_manageable) {
1081 		result = acpi_bus_get_perf_flags(device);
1082 		if (result)
1083 			goto end;
1084 	}
1085 
1086 	if ((result = acpi_device_set_context(device, type)))
1087 		goto end;
1088 
1089 	acpi_device_get_debug_info(device, handle, type);
1090 
1091 	acpi_device_register(device, parent);
1092 
1093 	/*
1094 	 * Bind _ADR-Based Devices
1095 	 * -----------------------
1096 	 * If there's a a bus address (_ADR) then we utilize the parent's
1097 	 * 'bind' function (if exists) to bind the ACPI- and natively-
1098 	 * enumerated device representations.
1099 	 */
1100 	if (device->flags.bus_address) {
1101 		if (device->parent && device->parent->ops.bind)
1102 			device->parent->ops.bind(device);
1103 	}
1104 
1105 	/*
1106 	 * Locate & Attach Driver
1107 	 * ----------------------
1108 	 * If there's a hardware id (_HID) or compatible ids (_CID) we check
1109 	 * to see if there's a driver installed for this kind of device.  Note
1110 	 * that drivers can install before or after a device is enumerated.
1111 	 *
1112 	 * TBD: Assumes LDM provides driver hot-plug capability.
1113 	 */
1114 	result = acpi_bus_find_driver(device);
1115 
1116       end:
1117 	if (!result)
1118 		*child = device;
1119 	else {
1120 		if (device->pnp.cid_list)
1121 			kfree(device->pnp.cid_list);
1122 		kfree(device);
1123 	}
1124 
1125 	return_VALUE(result);
1126 }
1127 
1128 static int acpi_bus_scan(struct acpi_device *start, struct acpi_bus_ops *ops)
1129 {
1130 	acpi_status status = AE_OK;
1131 	struct acpi_device *parent = NULL;
1132 	struct acpi_device *child = NULL;
1133 	acpi_handle phandle = NULL;
1134 	acpi_handle chandle = NULL;
1135 	acpi_object_type type = 0;
1136 	u32 level = 1;
1137 
1138 	ACPI_FUNCTION_TRACE("acpi_bus_scan");
1139 
1140 	if (!start)
1141 		return_VALUE(-EINVAL);
1142 
1143 	parent = start;
1144 	phandle = start->handle;
1145 
1146 	/*
1147 	 * Parse through the ACPI namespace, identify all 'devices', and
1148 	 * create a new 'struct acpi_device' for each.
1149 	 */
1150 	while ((level > 0) && parent) {
1151 
1152 		status = acpi_get_next_object(ACPI_TYPE_ANY, phandle,
1153 					      chandle, &chandle);
1154 
1155 		/*
1156 		 * If this scope is exhausted then move our way back up.
1157 		 */
1158 		if (ACPI_FAILURE(status)) {
1159 			level--;
1160 			chandle = phandle;
1161 			acpi_get_parent(phandle, &phandle);
1162 			if (parent->parent)
1163 				parent = parent->parent;
1164 			continue;
1165 		}
1166 
1167 		status = acpi_get_type(chandle, &type);
1168 		if (ACPI_FAILURE(status))
1169 			continue;
1170 
1171 		/*
1172 		 * If this is a scope object then parse it (depth-first).
1173 		 */
1174 		if (type == ACPI_TYPE_LOCAL_SCOPE) {
1175 			level++;
1176 			phandle = chandle;
1177 			chandle = NULL;
1178 			continue;
1179 		}
1180 
1181 		/*
1182 		 * We're only interested in objects that we consider 'devices'.
1183 		 */
1184 		switch (type) {
1185 		case ACPI_TYPE_DEVICE:
1186 			type = ACPI_BUS_TYPE_DEVICE;
1187 			break;
1188 		case ACPI_TYPE_PROCESSOR:
1189 			type = ACPI_BUS_TYPE_PROCESSOR;
1190 			break;
1191 		case ACPI_TYPE_THERMAL:
1192 			type = ACPI_BUS_TYPE_THERMAL;
1193 			break;
1194 		case ACPI_TYPE_POWER:
1195 			type = ACPI_BUS_TYPE_POWER;
1196 			break;
1197 		default:
1198 			continue;
1199 		}
1200 
1201 		if (ops->acpi_op_add)
1202 			status = acpi_add_single_object(&child, parent,
1203 							chandle, type);
1204 		else
1205 			status = acpi_bus_get_device(chandle, &child);
1206 
1207 		if (ACPI_FAILURE(status))
1208 			continue;
1209 
1210 		if (ops->acpi_op_start) {
1211 			status = acpi_start_single_object(child);
1212 			if (ACPI_FAILURE(status))
1213 				continue;
1214 		}
1215 
1216 		/*
1217 		 * If the device is present, enabled, and functioning then
1218 		 * parse its scope (depth-first).  Note that we need to
1219 		 * represent absent devices to facilitate PnP notifications
1220 		 * -- but only the subtree head (not all of its children,
1221 		 * which will be enumerated when the parent is inserted).
1222 		 *
1223 		 * TBD: Need notifications and other detection mechanisms
1224 		 *      in place before we can fully implement this.
1225 		 */
1226 		if (child->status.present) {
1227 			status = acpi_get_next_object(ACPI_TYPE_ANY, chandle,
1228 						      NULL, NULL);
1229 			if (ACPI_SUCCESS(status)) {
1230 				level++;
1231 				phandle = chandle;
1232 				chandle = NULL;
1233 				parent = child;
1234 			}
1235 		}
1236 	}
1237 
1238 	return_VALUE(0);
1239 }
1240 
1241 int
1242 acpi_bus_add(struct acpi_device **child,
1243 	     struct acpi_device *parent, acpi_handle handle, int type)
1244 {
1245 	int result;
1246 	struct acpi_bus_ops ops;
1247 
1248 	ACPI_FUNCTION_TRACE("acpi_bus_add");
1249 
1250 	result = acpi_add_single_object(child, parent, handle, type);
1251 	if (!result) {
1252 		memset(&ops, 0, sizeof(ops));
1253 		ops.acpi_op_add = 1;
1254 		result = acpi_bus_scan(*child, &ops);
1255 	}
1256 	return_VALUE(result);
1257 }
1258 
1259 EXPORT_SYMBOL(acpi_bus_add);
1260 
1261 int acpi_bus_start(struct acpi_device *device)
1262 {
1263 	int result;
1264 	struct acpi_bus_ops ops;
1265 
1266 	ACPI_FUNCTION_TRACE("acpi_bus_start");
1267 
1268 	if (!device)
1269 		return_VALUE(-EINVAL);
1270 
1271 	result = acpi_start_single_object(device);
1272 	if (!result) {
1273 		memset(&ops, 0, sizeof(ops));
1274 		ops.acpi_op_start = 1;
1275 		result = acpi_bus_scan(device, &ops);
1276 	}
1277 	return_VALUE(result);
1278 }
1279 
1280 EXPORT_SYMBOL(acpi_bus_start);
1281 
1282 static int acpi_bus_trim(struct acpi_device *start, int rmdevice)
1283 {
1284 	acpi_status status;
1285 	struct acpi_device *parent, *child;
1286 	acpi_handle phandle, chandle;
1287 	acpi_object_type type;
1288 	u32 level = 1;
1289 	int err = 0;
1290 
1291 	parent = start;
1292 	phandle = start->handle;
1293 	child = chandle = NULL;
1294 
1295 	while ((level > 0) && parent && (!err)) {
1296 		status = acpi_get_next_object(ACPI_TYPE_ANY, phandle,
1297 					      chandle, &chandle);
1298 
1299 		/*
1300 		 * If this scope is exhausted then move our way back up.
1301 		 */
1302 		if (ACPI_FAILURE(status)) {
1303 			level--;
1304 			chandle = phandle;
1305 			acpi_get_parent(phandle, &phandle);
1306 			child = parent;
1307 			parent = parent->parent;
1308 
1309 			if (level == 0)
1310 				err = acpi_bus_remove(child, rmdevice);
1311 			else
1312 				err = acpi_bus_remove(child, 1);
1313 
1314 			continue;
1315 		}
1316 
1317 		status = acpi_get_type(chandle, &type);
1318 		if (ACPI_FAILURE(status)) {
1319 			continue;
1320 		}
1321 		/*
1322 		 * If there is a device corresponding to chandle then
1323 		 * parse it (depth-first).
1324 		 */
1325 		if (acpi_bus_get_device(chandle, &child) == 0) {
1326 			level++;
1327 			phandle = chandle;
1328 			chandle = NULL;
1329 			parent = child;
1330 		}
1331 		continue;
1332 	}
1333 	return err;
1334 }
1335 
1336 static int acpi_bus_scan_fixed(struct acpi_device *root)
1337 {
1338 	int result = 0;
1339 	struct acpi_device *device = NULL;
1340 
1341 	ACPI_FUNCTION_TRACE("acpi_bus_scan_fixed");
1342 
1343 	if (!root)
1344 		return_VALUE(-ENODEV);
1345 
1346 	/*
1347 	 * Enumerate all fixed-feature devices.
1348 	 */
1349 	if (acpi_fadt.pwr_button == 0) {
1350 		result = acpi_add_single_object(&device, acpi_root,
1351 						NULL,
1352 						ACPI_BUS_TYPE_POWER_BUTTON);
1353 		if (!result)
1354 			result = acpi_start_single_object(device);
1355 	}
1356 
1357 	if (acpi_fadt.sleep_button == 0) {
1358 		result = acpi_add_single_object(&device, acpi_root,
1359 						NULL,
1360 						ACPI_BUS_TYPE_SLEEP_BUTTON);
1361 		if (!result)
1362 			result = acpi_start_single_object(device);
1363 	}
1364 
1365 	return_VALUE(result);
1366 }
1367 
1368 static int __init acpi_scan_init(void)
1369 {
1370 	int result;
1371 	struct acpi_bus_ops ops;
1372 
1373 	ACPI_FUNCTION_TRACE("acpi_scan_init");
1374 
1375 	if (acpi_disabled)
1376 		return_VALUE(0);
1377 
1378 	kset_register(&acpi_namespace_kset);
1379 
1380 	/*
1381 	 * Create the root device in the bus's device tree
1382 	 */
1383 	result = acpi_add_single_object(&acpi_root, NULL, ACPI_ROOT_OBJECT,
1384 					ACPI_BUS_TYPE_SYSTEM);
1385 	if (result)
1386 		goto Done;
1387 
1388 	result = acpi_start_single_object(acpi_root);
1389 
1390 	/*
1391 	 * Enumerate devices in the ACPI namespace.
1392 	 */
1393 	result = acpi_bus_scan_fixed(acpi_root);
1394 	if (!result) {
1395 		memset(&ops, 0, sizeof(ops));
1396 		ops.acpi_op_add = 1;
1397 		ops.acpi_op_start = 1;
1398 		result = acpi_bus_scan(acpi_root, &ops);
1399 	}
1400 
1401 	if (result)
1402 		acpi_device_unregister(acpi_root, ACPI_BUS_REMOVAL_NORMAL);
1403 
1404       Done:
1405 	return_VALUE(result);
1406 }
1407 
1408 subsys_initcall(acpi_scan_init);
1409