free electrons

Embedded Linux Experts

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
/*
 * drivers/acpi/power.c - ACPI Power Resources management.
 *
 * Copyright (C) 2001 - 2015 Intel Corp.
 * Author: Andy Grover <andrew.grover@intel.com>
 * Author: Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

/*
 * ACPI power-managed devices may be controlled in two ways:
 * 1. via "Device Specific (D-State) Control"
 * 2. via "Power Resource Control".
 * The code below deals with ACPI Power Resources control.
 * 
 * An ACPI "power resource object" represents a software controllable power
 * plane, clock plane, or other resource depended on by a device.
 *
 * A device may rely on multiple power resources, and a power resource
 * may be shared by multiple devices.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/sysfs.h>
#include <linux/acpi.h>
#include "sleep.h"
#include "internal.h"

#define _COMPONENT			ACPI_POWER_COMPONENT
ACPI_MODULE_NAME("power");
#define ACPI_POWER_CLASS		"power_resource"
#define ACPI_POWER_DEVICE_NAME		"Power Resource"
#define ACPI_POWER_FILE_INFO		"info"
#define ACPI_POWER_FILE_STATUS		"state"
#define ACPI_POWER_RESOURCE_STATE_OFF	0x00
#define ACPI_POWER_RESOURCE_STATE_ON	0x01
#define ACPI_POWER_RESOURCE_STATE_UNKNOWN 0xFF

struct acpi_power_resource {
	struct acpi_device device;
	struct list_head list_node;
	char *name;
	u32 system_level;
	u32 order;
	unsigned int ref_count;
	bool wakeup_enabled;
	struct mutex resource_lock;
};

struct acpi_power_resource_entry {
	struct list_head node;
	struct acpi_power_resource *resource;
};

static LIST_HEAD(acpi_power_resource_list);
static DEFINE_MUTEX(power_resource_list_lock);

/* --------------------------------------------------------------------------
                             Power Resource Management
   -------------------------------------------------------------------------- */

static inline
struct acpi_power_resource *to_power_resource(struct acpi_device *device)
{
	return container_of(device, struct acpi_power_resource, device);
}

static struct acpi_power_resource *acpi_power_get_context(acpi_handle handle)
{
	struct acpi_device *device;

	if (acpi_bus_get_device(handle, &device))
		return NULL;

	return to_power_resource(device);
}

static int acpi_power_resources_list_add(acpi_handle handle,
					 struct list_head *list)
{
	struct acpi_power_resource *resource = acpi_power_get_context(handle);
	struct acpi_power_resource_entry *entry;

	if (!resource || !list)
		return -EINVAL;

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry)
		return -ENOMEM;

	entry->resource = resource;
	if (!list_empty(list)) {
		struct acpi_power_resource_entry *e;

		list_for_each_entry(e, list, node)
			if (e->resource->order > resource->order) {
				list_add_tail(&entry->node, &e->node);
				return 0;
			}
	}
	list_add_tail(&entry->node, list);
	return 0;
}

void acpi_power_resources_list_free(struct list_head *list)
{
	struct acpi_power_resource_entry *entry, *e;

	list_for_each_entry_safe(entry, e, list, node) {
		list_del(&entry->node);
		kfree(entry);
	}
}

int acpi_extract_power_resources(union acpi_object *package, unsigned int start,
				 struct list_head *list)
{
	unsigned int i;
	int err = 0;

	for (i = start; i < package->package.count; i++) {
		union acpi_object *element = &package->package.elements[i];
		acpi_handle rhandle;

		if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
			err = -ENODATA;
			break;
		}
		rhandle = element->reference.handle;
		if (!rhandle) {
			err = -ENODEV;
			break;
		}
		err = acpi_add_power_resource(rhandle);
		if (err)
			break;

		err = acpi_power_resources_list_add(rhandle, list);
		if (err)
			break;
	}
	if (err)
		acpi_power_resources_list_free(list);

	return err;
}

static int acpi_power_get_state(acpi_handle handle, int *state)
{
	acpi_status status = AE_OK;
	unsigned long long sta = 0;
	char node_name[5];
	struct acpi_buffer buffer = { sizeof(node_name), node_name };


	if (!handle || !state)
		return -EINVAL;

	status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	*state = (sta & 0x01)?ACPI_POWER_RESOURCE_STATE_ON:
			      ACPI_POWER_RESOURCE_STATE_OFF;

	acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] is %s\n",
			  node_name,
				*state ? "on" : "off"));

	return 0;
}

static int acpi_power_get_list_state(struct list_head *list, int *state)
{
	struct acpi_power_resource_entry *entry;
	int cur_state;

	if (!list || !state)
		return -EINVAL;

	/* The state of the list is 'on' IFF all resources are 'on'. */
	cur_state = 0;
	list_for_each_entry(entry, list, node) {
		struct acpi_power_resource *resource = entry->resource;
		acpi_handle handle = resource->device.handle;
		int result;

		mutex_lock(&resource->resource_lock);
		result = acpi_power_get_state(handle, &cur_state);
		mutex_unlock(&resource->resource_lock);
		if (result)
			return result;

		if (cur_state != ACPI_POWER_RESOURCE_STATE_ON)
			break;
	}

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource list is %s\n",
			  cur_state ? "on" : "off"));

	*state = cur_state;
	return 0;
}

static int __acpi_power_on(struct acpi_power_resource *resource)
{
	acpi_status status = AE_OK;

	status = acpi_evaluate_object(resource->device.handle, "_ON", NULL, NULL);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Power resource [%s] turned on\n",
			  resource->name));

	return 0;
}

static int acpi_power_on_unlocked(struct acpi_power_resource *resource)
{
	int result = 0;

	if (resource->ref_count++) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "Power resource [%s] already on\n",
				  resource->name));
	} else {
		result = __acpi_power_on(resource);
		if (result)
			resource->ref_count--;
	}
	return result;
}

static int acpi_power_on(struct acpi_power_resource *resource)
{
	int result;

	mutex_lock(&resource->resource_lock);
	result = acpi_power_on_unlocked(resource);
	mutex_unlock(&resource->resource_lock);
	return result;
}

static int __acpi_power_off(struct acpi_power_resource *resource)
{
	acpi_status status;

	status = acpi_evaluate_object(resource->device.handle, "_OFF",
				      NULL, NULL);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Power resource [%s] turned off\n",
			  resource->name));
	return 0;
}

static int acpi_power_off_unlocked(struct acpi_power_resource *resource)
{
	int result = 0;

	if (!resource->ref_count) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "Power resource [%s] already off\n",
				  resource->name));
		return 0;
	}

	if (--resource->ref_count) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "Power resource [%s] still in use\n",
				  resource->name));
	} else {
		result = __acpi_power_off(resource);
		if (result)
			resource->ref_count++;
	}
	return result;
}

static int acpi_power_off(struct acpi_power_resource *resource)
{
	int result;

	mutex_lock(&resource->resource_lock);
	result = acpi_power_off_unlocked(resource);
	mutex_unlock(&resource->resource_lock);
	return result;
}

static int acpi_power_off_list(struct list_head *list)
{
	struct acpi_power_resource_entry *entry;
	int result = 0;

	list_for_each_entry_reverse(entry, list, node) {
		result = acpi_power_off(entry->resource);
		if (result)
			goto err;
	}
	return 0;

 err:
	list_for_each_entry_continue(entry, list, node)
		acpi_power_on(entry->resource);

	return result;
}

static int acpi_power_on_list(struct list_head *list)
{
	struct acpi_power_resource_entry *entry;
	int result = 0;

	list_for_each_entry(entry, list, node) {
		result = acpi_power_on(entry->resource);
		if (result)
			goto err;
	}
	return 0;

 err:
	list_for_each_entry_continue_reverse(entry, list, node)
		acpi_power_off(entry->resource);

	return result;
}

static struct attribute *attrs[] = {
	NULL,
};

static struct attribute_group attr_groups[] = {
	[ACPI_STATE_D0] = {
		.name = "power_resources_D0",
		.attrs = attrs,
	},
	[ACPI_STATE_D1] = {
		.name = "power_resources_D1",
		.attrs = attrs,
	},
	[ACPI_STATE_D2] = {
		.name = "power_resources_D2",
		.attrs = attrs,
	},
	[ACPI_STATE_D3_HOT] = {
		.name = "power_resources_D3hot",
		.attrs = attrs,
	},
};

static struct attribute_group wakeup_attr_group = {
	.name = "power_resources_wakeup",
	.attrs = attrs,
};

static void acpi_power_hide_list(struct acpi_device *adev,
				 struct list_head *resources,
				 struct attribute_group *attr_group)
{
	struct acpi_power_resource_entry *entry;

	if (list_empty(resources))
		return;

	list_for_each_entry_reverse(entry, resources, node) {
		struct acpi_device *res_dev = &entry->resource->device;

		sysfs_remove_link_from_group(&adev->dev.kobj,
					     attr_group->name,
					     dev_name(&res_dev->dev));
	}
	sysfs_remove_group(&adev->dev.kobj, attr_group);
}

static void acpi_power_expose_list(struct acpi_device *adev,
				   struct list_head *resources,
				   struct attribute_group *attr_group)
{
	struct acpi_power_resource_entry *entry;
	int ret;

	if (list_empty(resources))
		return;

	ret = sysfs_create_group(&adev->dev.kobj, attr_group);
	if (ret)
		return;

	list_for_each_entry(entry, resources, node) {
		struct acpi_device *res_dev = &entry->resource->device;

		ret = sysfs_add_link_to_group(&adev->dev.kobj,
					      attr_group->name,
					      &res_dev->dev.kobj,
					      dev_name(&res_dev->dev));
		if (ret) {
			acpi_power_hide_list(adev, resources, attr_group);
			break;
		}
	}
}

static void acpi_power_expose_hide(struct acpi_device *adev,
				   struct list_head *resources,
				   struct attribute_group *attr_group,
				   bool expose)
{
	if (expose)
		acpi_power_expose_list(adev, resources, attr_group);
	else
		acpi_power_hide_list(adev, resources, attr_group);
}

void acpi_power_add_remove_device(struct acpi_device *adev, bool add)
{
	int state;

	if (adev->wakeup.flags.valid)
		acpi_power_expose_hide(adev, &adev->wakeup.resources,
				       &wakeup_attr_group, add);

	if (!adev->power.flags.power_resources)
		return;

	for (state = ACPI_STATE_D0; state <= ACPI_STATE_D3_HOT; state++)
		acpi_power_expose_hide(adev,
				       &adev->power.states[state].resources,
				       &attr_groups[state], add);
}

int acpi_power_wakeup_list_init(struct list_head *list, int *system_level_p)
{
	struct acpi_power_resource_entry *entry;
	int system_level = 5;

	list_for_each_entry(entry, list, node) {
		struct acpi_power_resource *resource = entry->resource;
		acpi_handle handle = resource->device.handle;
		int result;
		int state;

		mutex_lock(&resource->resource_lock);

		result = acpi_power_get_state(handle, &state);
		if (result) {
			mutex_unlock(&resource->resource_lock);
			return result;
		}
		if (state == ACPI_POWER_RESOURCE_STATE_ON) {
			resource->ref_count++;
			resource->wakeup_enabled = true;
		}
		if (system_level > resource->system_level)
			system_level = resource->system_level;

		mutex_unlock(&resource->resource_lock);
	}
	*system_level_p = system_level;
	return 0;
}

/* --------------------------------------------------------------------------
                             Device Power Management
   -------------------------------------------------------------------------- */

/**
 * acpi_device_sleep_wake - execute _DSW (Device Sleep Wake) or (deprecated in
 *                          ACPI 3.0) _PSW (Power State Wake)
 * @dev: Device to handle.
 * @enable: 0 - disable, 1 - enable the wake capabilities of the device.
 * @sleep_state: Target sleep state of the system.
 * @dev_state: Target power state of the device.
 *
 * Execute _DSW (Device Sleep Wake) or (deprecated in ACPI 3.0) _PSW (Power
 * State Wake) for the device, if present.  On failure reset the device's
 * wakeup.flags.valid flag.
 *
 * RETURN VALUE:
 * 0 if either _DSW or _PSW has been successfully executed
 * 0 if neither _DSW nor _PSW has been found
 * -ENODEV if the execution of either _DSW or _PSW has failed
 */
int acpi_device_sleep_wake(struct acpi_device *dev,
                           int enable, int sleep_state, int dev_state)
{
	union acpi_object in_arg[3];
	struct acpi_object_list arg_list = { 3, in_arg };
	acpi_status status = AE_OK;

	/*
	 * Try to execute _DSW first.
	 *
	 * Three agruments are needed for the _DSW object:
	 * Argument 0: enable/disable the wake capabilities
	 * Argument 1: target system state
	 * Argument 2: target device state
	 * When _DSW object is called to disable the wake capabilities, maybe
	 * the first argument is filled. The values of the other two agruments
	 * are meaningless.
	 */
	in_arg[0].type = ACPI_TYPE_INTEGER;
	in_arg[0].integer.value = enable;
	in_arg[1].type = ACPI_TYPE_INTEGER;
	in_arg[1].integer.value = sleep_state;
	in_arg[2].type = ACPI_TYPE_INTEGER;
	in_arg[2].integer.value = dev_state;
	status = acpi_evaluate_object(dev->handle, "_DSW", &arg_list, NULL);
	if (ACPI_SUCCESS(status)) {
		return 0;
	} else if (status != AE_NOT_FOUND) {
		printk(KERN_ERR PREFIX "_DSW execution failed\n");
		dev->wakeup.flags.valid = 0;
		return -ENODEV;
	}

	/* Execute _PSW */
	status = acpi_execute_simple_method(dev->handle, "_PSW", enable);
	if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
		printk(KERN_ERR PREFIX "_PSW execution failed\n");
		dev->wakeup.flags.valid = 0;
		return -ENODEV;
	}

	return 0;
}

/*
 * Prepare a wakeup device, two steps (Ref ACPI 2.0:P229):
 * 1. Power on the power resources required for the wakeup device 
 * 2. Execute _DSW (Device Sleep Wake) or (deprecated in ACPI 3.0) _PSW (Power
 *    State Wake) for the device, if present
 */
int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state)
{
	struct acpi_power_resource_entry *entry;
	int err = 0;

	if (!dev || !dev->wakeup.flags.valid)
		return -EINVAL;

	mutex_lock(&acpi_device_lock);

	if (dev->wakeup.prepare_count++)
		goto out;

	list_for_each_entry(entry, &dev->wakeup.resources, node) {
		struct acpi_power_resource *resource = entry->resource;

		mutex_lock(&resource->resource_lock);

		if (!resource->wakeup_enabled) {
			err = acpi_power_on_unlocked(resource);
			if (!err)
				resource->wakeup_enabled = true;
		}

		mutex_unlock(&resource->resource_lock);

		if (err) {
			dev_err(&dev->dev,
				"Cannot turn wakeup power resources on\n");
			dev->wakeup.flags.valid = 0;
			goto out;
		}
	}
	/*
	 * Passing 3 as the third argument below means the device may be
	 * put into arbitrary power state afterward.
	 */
	err = acpi_device_sleep_wake(dev, 1, sleep_state, 3);
	if (err)
		dev->wakeup.prepare_count = 0;

 out:
	mutex_unlock(&acpi_device_lock);
	return err;
}

/*
 * Shutdown a wakeup device, counterpart of above method
 * 1. Execute _DSW (Device Sleep Wake) or (deprecated in ACPI 3.0) _PSW (Power
 *    State Wake) for the device, if present
 * 2. Shutdown down the power resources
 */
int acpi_disable_wakeup_device_power(struct acpi_device *dev)
{
	struct acpi_power_resource_entry *entry;
	int err = 0;

	if (!dev || !dev->wakeup.flags.valid)
		return -EINVAL;

	mutex_lock(&acpi_device_lock);

	if (--dev->wakeup.prepare_count > 0)
		goto out;

	/*
	 * Executing the code below even if prepare_count is already zero when
	 * the function is called may be useful, for example for initialisation.
	 */
	if (dev->wakeup.prepare_count < 0)
		dev->wakeup.prepare_count = 0;

	err = acpi_device_sleep_wake(dev, 0, 0, 0);
	if (err)
		goto out;

	list_for_each_entry(entry, &dev->wakeup.resources, node) {
		struct acpi_power_resource *resource = entry->resource;

		mutex_lock(&resource->resource_lock);

		if (resource->wakeup_enabled) {
			err = acpi_power_off_unlocked(resource);
			if (!err)
				resource->wakeup_enabled = false;
		}

		mutex_unlock(&resource->resource_lock);

		if (err) {
			dev_err(&dev->dev,
				"Cannot turn wakeup power resources off\n");
			dev->wakeup.flags.valid = 0;
			break;
		}
	}

 out:
	mutex_unlock(&acpi_device_lock);
	return err;
}

int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
{
	int result = 0;
	int list_state = 0;
	int i = 0;

	if (!device || !state)
		return -EINVAL;

	/*
	 * We know a device's inferred power state when all the resources
	 * required for a given D-state are 'on'.
	 */
	for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++) {
		struct list_head *list = &device->power.states[i].resources;

		if (list_empty(list))
			continue;

		result = acpi_power_get_list_state(list, &list_state);
		if (result)
			return result;

		if (list_state == ACPI_POWER_RESOURCE_STATE_ON) {
			*state = i;
			return 0;
		}
	}

	*state = device->power.states[ACPI_STATE_D3_COLD].flags.valid ?
		ACPI_STATE_D3_COLD : ACPI_STATE_D3_HOT;
	return 0;
}

int acpi_power_on_resources(struct acpi_device *device, int state)
{
	if (!device || state < ACPI_STATE_D0 || state > ACPI_STATE_D3_HOT)
		return -EINVAL;

	return acpi_power_on_list(&device->power.states[state].resources);
}

int acpi_power_transition(struct acpi_device *device, int state)
{
	int result = 0;

	if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3_COLD))
		return -EINVAL;

	if (device->power.state == state || !device->flags.power_manageable)
		return 0;

	if ((device->power.state < ACPI_STATE_D0)
	    || (device->power.state > ACPI_STATE_D3_COLD))
		return -ENODEV;

	/*
	 * First we reference all power resources required in the target list
	 * (e.g. so the device doesn't lose power while transitioning).  Then,
	 * we dereference all power resources used in the current list.
	 */
	if (state < ACPI_STATE_D3_COLD)
		result = acpi_power_on_list(
			&device->power.states[state].resources);

	if (!result && device->power.state < ACPI_STATE_D3_COLD)
		acpi_power_off_list(
			&device->power.states[device->power.state].resources);

	/* We shouldn't change the state unless the above operations succeed. */
	device->power.state = result ? ACPI_STATE_UNKNOWN : state;

	return result;
}

static void acpi_release_power_resource(struct device *dev)
{
	struct acpi_device *device = to_acpi_device(dev);
	struct acpi_power_resource *resource;

	resource = container_of(device, struct acpi_power_resource, device);

	mutex_lock(&power_resource_list_lock);
	list_del(&resource->list_node);
	mutex_unlock(&power_resource_list_lock);

	acpi_free_pnp_ids(&device->pnp);
	kfree(resource);
}

static ssize_t acpi_power_in_use_show(struct device *dev,
				      struct device_attribute *attr,
				      char *buf) {
	struct acpi_power_resource *resource;

	resource = to_power_resource(to_acpi_device(dev));
	return sprintf(buf, "%u\n", !!resource->ref_count);
}
static DEVICE_ATTR(resource_in_use, 0444, acpi_power_in_use_show, NULL);

static void acpi_power_sysfs_remove(struct acpi_device *device)
{
	device_remove_file(&device->dev, &dev_attr_resource_in_use);
}

static void acpi_power_add_resource_to_list(struct acpi_power_resource *resource)
{
	mutex_lock(&power_resource_list_lock);

	if (!list_empty(&acpi_power_resource_list)) {
		struct acpi_power_resource *r;

		list_for_each_entry(r, &acpi_power_resource_list, list_node)
			if (r->order > resource->order) {
				list_add_tail(&resource->list_node, &r->list_node);
				goto out;
			}
	}
	list_add_tail(&resource->list_node, &acpi_power_resource_list);

 out:
	mutex_unlock(&power_resource_list_lock);
}

int acpi_add_power_resource(acpi_handle handle)
{
	struct acpi_power_resource *resource;
	struct acpi_device *device = NULL;
	union acpi_object acpi_object;
	struct acpi_buffer buffer = { sizeof(acpi_object), &acpi_object };
	acpi_status status;
	int state, result = -ENODEV;

	acpi_bus_get_device(handle, &device);
	if (device)
		return 0;

	resource = kzalloc(sizeof(*resource), GFP_KERNEL);
	if (!resource)
		return -ENOMEM;

	device = &resource->device;
	acpi_init_device_object(device, handle, ACPI_BUS_TYPE_POWER,
				ACPI_STA_DEFAULT);
	mutex_init(&resource->resource_lock);
	INIT_LIST_HEAD(&resource->list_node);
	resource->name = device->pnp.bus_id;
	strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
	strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
	device->power.state = ACPI_STATE_UNKNOWN;

	/* Evalute the object to get the system level and resource order. */
	status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
	if (ACPI_FAILURE(status))
		goto err;

	resource->system_level = acpi_object.power_resource.system_level;
	resource->order = acpi_object.power_resource.resource_order;

	result = acpi_power_get_state(handle, &state);
	if (result)
		goto err;

	printk(KERN_INFO PREFIX "%s [%s] (%s)\n", acpi_device_name(device),
	       acpi_device_bid(device), state ? "on" : "off");

	device->flags.match_driver = true;
	result = acpi_device_add(device, acpi_release_power_resource);
	if (result)
		goto err;

	if (!device_create_file(&device->dev, &dev_attr_resource_in_use))
		device->remove = acpi_power_sysfs_remove;

	acpi_power_add_resource_to_list(resource);
	acpi_device_add_finalize(device);
	return 0;

 err:
	acpi_release_power_resource(&device->dev);
	return result;
}

#ifdef CONFIG_ACPI_SLEEP
void acpi_resume_power_resources(void)
{
	struct acpi_power_resource *resource;

	mutex_lock(&power_resource_list_lock);

	list_for_each_entry(resource, &acpi_power_resource_list, list_node) {
		int result, state;

		mutex_lock(&resource->resource_lock);

		result = acpi_power_get_state(resource->device.handle, &state);
		if (result) {
			mutex_unlock(&resource->resource_lock);
			continue;
		}

		if (state == ACPI_POWER_RESOURCE_STATE_OFF
		    && resource->ref_count) {
			dev_info(&resource->device.dev, "Turning ON\n");
			__acpi_power_on(resource);
		}

		mutex_unlock(&resource->resource_lock);
	}
	list_for_each_entry_reverse(resource, &acpi_power_resource_list, list_node) {
		int result, state;

		mutex_lock(&resource->resource_lock);

		result = acpi_power_get_state(resource->device.handle, &state);
		if (result) {
			mutex_unlock(&resource->resource_lock);
			continue;
		}

		if (state == ACPI_POWER_RESOURCE_STATE_ON
		    && !resource->ref_count) {
			dev_info(&resource->device.dev, "Turning OFF\n");
			__acpi_power_off(resource);
		}

		mutex_unlock(&resource->resource_lock);
	}

	mutex_unlock(&power_resource_list_lock);
}
#endif