aboutsummaryrefslogtreecommitdiff
path: root/drivers/acpi/processor_throttling.c
blob: c26c61fb36c3ac0a16f719016f1a8634bfda71db (plain)
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
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
/*
 * processor_throttling.c - Throttling submodule of the ACPI processor driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *  Copyright (C) 2004       Dominik Brodowski <linux@brodo.de>
 *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
 *  			- Added processor hotplug support
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>

#include <asm/io.h>
#include <asm/uaccess.h>

#include <acpi/acpi_bus.h>
#include <acpi/processor.h>

#define ACPI_PROCESSOR_COMPONENT        0x01000000
#define ACPI_PROCESSOR_CLASS            "processor"
#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_throttling");

static int acpi_processor_get_throttling(struct acpi_processor *pr);
int acpi_processor_set_throttling(struct acpi_processor *pr, int state);

/*
 * _TPC - Throttling Present Capabilities
 */
static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
{
	acpi_status status = 0;
	unsigned long tpc = 0;

	if (!pr)
		return -EINVAL;
	status = acpi_evaluate_integer(pr->handle, "_TPC", NULL, &tpc);
	if (ACPI_FAILURE(status)) {
		if (status != AE_NOT_FOUND) {
			ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TPC"));
		}
		return -ENODEV;
	}
	pr->throttling_platform_limit = (int)tpc;
	return 0;
}

int acpi_processor_tstate_has_changed(struct acpi_processor *pr)
{
	int result = 0;
	int throttling_limit;
	int current_state;
	struct acpi_processor_limit *limit;
	int target_state;

	result = acpi_processor_get_platform_limit(pr);
	if (result) {
		/* Throttling Limit is unsupported */
		return result;
	}

	throttling_limit = pr->throttling_platform_limit;
	if (throttling_limit >= pr->throttling.state_count) {
		/* Uncorrect Throttling Limit */
		return -EINVAL;
	}

	current_state = pr->throttling.state;
	if (current_state > throttling_limit) {
		/*
		 * The current state can meet the requirement of
		 * _TPC limit. But it is reasonable that OSPM changes
		 * t-states from high to low for better performance.
		 * Of course the limit condition of thermal
		 * and user should be considered.
		 */
		limit = &pr->limit;
		target_state = throttling_limit;
		if (limit->thermal.tx > target_state)
			target_state = limit->thermal.tx;
		if (limit->user.tx > target_state)
			target_state = limit->user.tx;
	} else if (current_state == throttling_limit) {
		/*
		 * Unnecessary to change the throttling state
		 */
		return 0;
	} else {
		/*
		 * If the current state is lower than the limit of _TPC, it
		 * will be forced to switch to the throttling state defined
		 * by throttling_platfor_limit.
		 * Because the previous state meets with the limit condition
		 * of thermal and user, it is unnecessary to check it again.
		 */
		target_state = throttling_limit;
	}
	return acpi_processor_set_throttling(pr, target_state);
}

/*
 * _PTC - Processor Throttling Control (and status) register location
 */
static int acpi_processor_get_throttling_control(struct acpi_processor *pr)
{
	int result = 0;
	acpi_status status = 0;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object *ptc = NULL;
	union acpi_object obj = { 0 };
	struct acpi_processor_throttling *throttling;

	status = acpi_evaluate_object(pr->handle, "_PTC", NULL, &buffer);
	if (ACPI_FAILURE(status)) {
		if (status != AE_NOT_FOUND) {
			ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PTC"));
		}
		return -ENODEV;
	}

	ptc = (union acpi_object *)buffer.pointer;
	if (!ptc || (ptc->type != ACPI_TYPE_PACKAGE)
	    || (ptc->package.count != 2)) {
		printk(KERN_ERR PREFIX "Invalid _PTC data\n");
		result = -EFAULT;
		goto end;
	}

	/*
	 * control_register
	 */

	obj = ptc->package.elements[0];

	if ((obj.type != ACPI_TYPE_BUFFER)
	    || (obj.buffer.length < sizeof(struct acpi_ptc_register))
	    || (obj.buffer.pointer == NULL)) {
		printk(KERN_ERR PREFIX
		       "Invalid _PTC data (control_register)\n");
		result = -EFAULT;
		goto end;
	}
	memcpy(&pr->throttling.control_register, obj.buffer.pointer,
	       sizeof(struct acpi_ptc_register));

	/*
	 * status_register
	 */

	obj = ptc->package.elements[1];

	if ((obj.type != ACPI_TYPE_BUFFER)
	    || (obj.buffer.length < sizeof(struct acpi_ptc_register))
	    || (obj.buffer.pointer == NULL)) {
		printk(KERN_ERR PREFIX "Invalid _PTC data (status_register)\n");
		result = -EFAULT;
		goto end;
	}

	memcpy(&pr->throttling.status_register, obj.buffer.pointer,
	       sizeof(struct acpi_ptc_register));

	throttling = &pr->throttling;

	if ((throttling->control_register.bit_width +
		throttling->control_register.bit_offset) > 32) {
		printk(KERN_ERR PREFIX "Invalid _PTC control register\n");
		result = -EFAULT;
		goto end;
	}

	if ((throttling->status_register.bit_width +
		throttling->status_register.bit_offset) > 32) {
		printk(KERN_ERR PREFIX "Invalid _PTC status register\n");
		result = -EFAULT;
		goto end;
	}

      end:
	kfree(buffer.pointer);

	return result;
}

/*
 * _TSS - Throttling Supported States
 */
static int acpi_processor_get_throttling_states(struct acpi_processor *pr)
{
	int result = 0;
	acpi_status status = AE_OK;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	struct acpi_buffer format = { sizeof("NNNNN"), "NNNNN" };
	struct acpi_buffer state = { 0, NULL };
	union acpi_object *tss = NULL;
	int i;

	status = acpi_evaluate_object(pr->handle, "_TSS", NULL, &buffer);
	if (ACPI_FAILURE(status)) {
		if (status != AE_NOT_FOUND) {
			ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSS"));
		}
		return -ENODEV;
	}

	tss = buffer.pointer;
	if (!tss || (tss->type != ACPI_TYPE_PACKAGE)) {
		printk(KERN_ERR PREFIX "Invalid _TSS data\n");
		result = -EFAULT;
		goto end;
	}

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
			  tss->package.count));

	pr->throttling.state_count = tss->package.count;
	pr->throttling.states_tss =
	    kmalloc(sizeof(struct acpi_processor_tx_tss) * tss->package.count,
		    GFP_KERNEL);
	if (!pr->throttling.states_tss) {
		result = -ENOMEM;
		goto end;
	}

	for (i = 0; i < pr->throttling.state_count; i++) {

		struct acpi_processor_tx_tss *tx =
		    (struct acpi_processor_tx_tss *)&(pr->throttling.
						      states_tss[i]);

		state.length = sizeof(struct acpi_processor_tx_tss);
		state.pointer = tx;

		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Extracting state %d\n", i));

		status = acpi_extract_package(&(tss->package.elements[i]),
					      &format, &state);
		if (ACPI_FAILURE(status)) {
			ACPI_EXCEPTION((AE_INFO, status, "Invalid _TSS data"));
			result = -EFAULT;
			kfree(pr->throttling.states_tss);
			goto end;
		}

		if (!tx->freqpercentage) {
			printk(KERN_ERR PREFIX
			       "Invalid _TSS data: freq is zero\n");
			result = -EFAULT;
			kfree(pr->throttling.states_tss);
			goto end;
		}
	}

      end:
	kfree(buffer.pointer);

	return result;
}

/*
 * _TSD - T-State Dependencies
 */
static int acpi_processor_get_tsd(struct acpi_processor *pr)
{
	int result = 0;
	acpi_status status = AE_OK;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	struct acpi_buffer format = { sizeof("NNNNN"), "NNNNN" };
	struct acpi_buffer state = { 0, NULL };
	union acpi_object *tsd = NULL;
	struct acpi_tsd_package *pdomain;

	status = acpi_evaluate_object(pr->handle, "_TSD", NULL, &buffer);
	if (ACPI_FAILURE(status)) {
		if (status != AE_NOT_FOUND) {
			ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSD"));
		}
		return -ENODEV;
	}

	tsd = buffer.pointer;
	if (!tsd || (tsd->type != ACPI_TYPE_PACKAGE)) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid _TSD data\n"));
		result = -EFAULT;
		goto end;
	}

	if (tsd->package.count != 1) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid _TSD data\n"));
		result = -EFAULT;
		goto end;
	}

	pdomain = &(pr->throttling.domain_info);

	state.length = sizeof(struct acpi_tsd_package);
	state.pointer = pdomain;

	status = acpi_extract_package(&(tsd->package.elements[0]),
				      &format, &state);
	if (ACPI_FAILURE(status)) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid _TSD data\n"));
		result = -EFAULT;
		goto end;
	}

	if (pdomain->num_entries != ACPI_TSD_REV0_ENTRIES) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Unknown _TSD:num_entries\n"));
		result = -EFAULT;
		goto end;
	}

	if (pdomain->revision != ACPI_TSD_REV0_REVISION) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Unknown _TSD:revision\n"));
		result = -EFAULT;
		goto end;
	}

      end:
	kfree(buffer.pointer);
	return result;
}

/* --------------------------------------------------------------------------
                              Throttling Control
   -------------------------------------------------------------------------- */
static int acpi_processor_get_throttling_fadt(struct acpi_processor *pr)
{
	int state = 0;
	u32 value = 0;
	u32 duty_mask = 0;
	u32 duty_value = 0;

	if (!pr)
		return -EINVAL;

	if (!pr->flags.throttling)
		return -ENODEV;

	pr->throttling.state = 0;

	duty_mask = pr->throttling.state_count - 1;

	duty_mask <<= pr->throttling.duty_offset;

	local_irq_disable();

	value = inl(pr->throttling.address);

	/*
	 * Compute the current throttling state when throttling is enabled
	 * (bit 4 is on).
	 */
	if (value & 0x10) {
		duty_value = value & duty_mask;
		duty_value >>= pr->throttling.duty_offset;

		if (duty_value)
			state = pr->throttling.state_count - duty_value;
	}

	pr->throttling.state = state;

	local_irq_enable();

	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
			  "Throttling state is T%d (%d%% throttling applied)\n",
			  state, pr->throttling.states[state].performance));

	return 0;
}

#ifdef CONFIG_X86
static int acpi_throttling_rdmsr(struct acpi_processor *pr,
					acpi_integer * value)
{
	struct cpuinfo_x86 *c;
	u64 msr_high, msr_low;
	unsigned int cpu;
	u64 msr = 0;
	int ret = -1;

	cpu = pr->id;
	c = &cpu_data(cpu);

	if ((c->x86_vendor != X86_VENDOR_INTEL) ||
		!cpu_has(c, X86_FEATURE_ACPI)) {
		printk(KERN_ERR PREFIX
			"HARDWARE addr space,NOT supported yet\n");
	} else {
		msr_low = 0;
		msr_high = 0;
		rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL,
			(u32 *)&msr_low , (u32 *) &msr_high);
		msr = (msr_high << 32) | msr_low;
		*value = (acpi_integer) msr;
		ret = 0;
	}
	return ret;
}

static int acpi_throttling_wrmsr(struct acpi_processor *pr, acpi_integer value)
{
	struct cpuinfo_x86 *c;
	unsigned int cpu;
	int ret = -1;
	u64 msr;

	cpu = pr->id;
	c = &cpu_data(cpu);

	if ((c->x86_vendor != X86_VENDOR_INTEL) ||
		!cpu_has(c, X86_FEATURE_ACPI)) {
		printk(KERN_ERR PREFIX
			"HARDWARE addr space,NOT supported yet\n");
	} else {
		msr = value;
		wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL,
			msr & 0xffffffff, msr >> 32);
		ret = 0;
	}
	return ret;
}
#else
static int acpi_throttling_rdmsr(struct acpi_processor *pr,
				acpi_integer * value)
{
	printk(KERN_ERR PREFIX
		"HARDWARE addr space,NOT supported yet\n");
	return -1;
}

static int acpi_throttling_wrmsr(struct acpi_processor *pr, acpi_integer value)
{
	printk(KERN_ERR PREFIX
		"HARDWARE addr space,NOT supported yet\n");
	return -1;
}
#endif

static int acpi_read_throttling_status(struct acpi_processor *pr,
					acpi_integer *value)
{
	u32 bit_width, bit_offset;
	u64 ptc_value;
	u64 ptc_mask;
	struct acpi_processor_throttling *throttling;
	int ret = -1;

	throttling = &pr->throttling;
	switch (throttling->status_register.space_id) {
	case ACPI_ADR_SPACE_SYSTEM_IO:
		ptc_value = 0;
		bit_width = throttling->status_register.bit_width;
		bit_offset = throttling->status_register.bit_offset;

		acpi_os_read_port((acpi_io_address) throttling->status_register.
				  address, (u32 *) &ptc_value,
				  (u32) (bit_width + bit_offset));
		ptc_mask = (1 << bit_width) - 1;
		*value = (acpi_integer) ((ptc_value >> bit_offset) & ptc_mask);
		ret = 0;
		break;
	case ACPI_ADR_SPACE_FIXED_HARDWARE:
		ret = acpi_throttling_rdmsr(pr, value);
		break;
	default:
		printk(KERN_ERR PREFIX "Unknown addr space %d\n",
		       (u32) (throttling->status_register.space_id));
	}
	return ret;
}

static int acpi_write_throttling_state(struct acpi_processor *pr,
				acpi_integer value)
{
	u32 bit_width, bit_offset;
	u64 ptc_value;
	u64 ptc_mask;
	struct acpi_processor_throttling *throttling;
	int ret = -1;

	throttling = &pr->throttling;
	switch (throttling->control_register.space_id) {
	case ACPI_ADR_SPACE_SYSTEM_IO:
		bit_width = throttling->control_register.bit_width;
		bit_offset = throttling->control_register.bit_offset;
		ptc_mask = (1 << bit_width) - 1;
		ptc_value = value & ptc_mask;

		acpi_os_write_port((acpi_io_address) throttling->
					control_register.address,
					(u32) (ptc_value << bit_offset),
					(u32) (bit_width + bit_offset));
		ret = 0;
		break;
	case ACPI_ADR_SPACE_FIXED_HARDWARE:
		ret = acpi_throttling_wrmsr(pr, value);
		break;
	default:
		printk(KERN_ERR PREFIX "Unknown addr space %d\n",
		       (u32) (throttling->control_register.space_id));
	}
	return ret;
}

static int acpi_get_throttling_state(struct acpi_processor *pr,
				acpi_integer value)
{
	int i;

	for (i = 0; i < pr->throttling.state_count; i++) {
		struct acpi_processor_tx_tss *tx =
		    (struct acpi_processor_tx_tss *)&(pr->throttling.
						      states_tss[i]);
		if (tx->control == value)
			break;
	}
	if (i > pr->throttling.state_count)
		i = -1;
	return i;
}

static int acpi_get_throttling_value(struct acpi_processor *pr,
			int state, acpi_integer *value)
{
	int ret = -1;

	if (state >= 0 && state <= pr->throttling.state_count) {
		struct acpi_processor_tx_tss *tx =
		    (struct acpi_processor_tx_tss *)&(pr->throttling.
						      states_tss[state]);
		*value = tx->control;
		ret = 0;
	}
	return ret;
}

static int acpi_processor_get_throttling_ptc(struct acpi_processor *pr)
{
	int state = 0;
	int ret;
	acpi_integer value;

	if (!pr)
		return -EINVAL;

	if (!pr->flags.throttling)
		return -ENODEV;

	pr->throttling.state = 0;
	local_irq_disable();
	value = 0;
	ret = acpi_read_throttling_status(pr, &value);
	if (ret >= 0) {
		state = acpi_get_throttling_state(pr, value);
		pr->throttling.state = state;
	}
	local_irq_enable();

	return 0;
}

static int acpi_processor_get_throttling(struct acpi_processor *pr)
{
	return pr->throttling.acpi_processor_get_throttling(pr);
}

static int acpi_processor_get_fadt_info(struct acpi_processor *pr)
{
	int i, step;

	if (!pr->throttling.address) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
		return -EINVAL;
	} else if (!pr->throttling.duty_width) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
		return -EINVAL;
	}
	/* TBD: Support duty_cycle values that span bit 4. */
	else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) {
		printk(KERN_WARNING PREFIX "duty_cycle spans bit 4\n");
		return -EINVAL;
	}

	pr->throttling.state_count = 1 << acpi_gbl_FADT.duty_width;

	/*
	 * Compute state values. Note that throttling displays a linear power
	 * performance relationship (at 50% performance the CPU will consume
	 * 50% power).  Values are in 1/10th of a percent to preserve accuracy.
	 */

	step = (1000 / pr->throttling.state_count);

	for (i = 0; i < pr->throttling.state_count; i++) {
		pr->throttling.states[i].performance = 1000 - step * i;
		pr->throttling.states[i].power = 1000 - step * i;
	}
	return 0;
}

static int acpi_processor_set_throttling_fadt(struct acpi_processor *pr,
					      int state)
{
	u32 value = 0;
	u32 duty_mask = 0;
	u32 duty_value = 0;

	if (!pr)
		return -EINVAL;

	if ((state < 0) || (state > (pr->throttling.state_count - 1)))
		return -EINVAL;

	if (!pr->flags.throttling)
		return -ENODEV;

	if (state == pr->throttling.state)
		return 0;

	if (state < pr->throttling_platform_limit)
		return -EPERM;
	/*
	 * Calculate the duty_value and duty_mask.
	 */
	if (state) {
		duty_value = pr->throttling.state_count - state;

		duty_value <<= pr->throttling.duty_offset;

		/* Used to clear all duty_value bits */
		duty_mask = pr->throttling.state_count - 1;

		duty_mask <<= acpi_gbl_FADT.duty_offset;
		duty_mask = ~duty_mask;
	}

	local_irq_disable();

	/*
	 * Disable throttling by writing a 0 to bit 4.  Note that we must
	 * turn it off before you can change the duty_value.
	 */
	value = inl(pr->throttling.address);
	if (value & 0x10) {
		value &= 0xFFFFFFEF;
		outl(value, pr->throttling.address);
	}

	/*
	 * Write the new duty_value and then enable throttling.  Note
	 * that a state value of 0 leaves throttling disabled.
	 */
	if (state) {
		value &= duty_mask;
		value |= duty_value;
		outl(value, pr->throttling.address);

		value |= 0x00000010;
		outl(value, pr->throttling.address);
	}

	pr->throttling.state = state;

	local_irq_enable();

	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
			  "Throttling state set to T%d (%d%%)\n", state,
			  (pr->throttling.states[state].performance ? pr->
			   throttling.states[state].performance / 10 : 0)));

	return 0;
}

static int acpi_processor_set_throttling_ptc(struct acpi_processor *pr,
					     int state)
{
	int ret;
	acpi_integer value;

	if (!pr)
		return -EINVAL;

	if ((state < 0) || (state > (pr->throttling.state_count - 1)))
		return -EINVAL;

	if (!pr->flags.throttling)
		return -ENODEV;

	if (state == pr->throttling.state)
		return 0;

	if (state < pr->throttling_platform_limit)
		return -EPERM;

	local_irq_disable();
	value = 0;
	ret = acpi_get_throttling_value(pr, state, &value);
	if (ret >= 0) {
		acpi_write_throttling_state(pr, value);
		pr->throttling.state = state;
	}
	local_irq_enable();

	return 0;
}

int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
{
	return pr->throttling.acpi_processor_set_throttling(pr, state);
}

int acpi_processor_get_throttling_info(struct acpi_processor *pr)
{
	int result = 0;

	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
			  "pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
			  pr->throttling.address,
			  pr->throttling.duty_offset,
			  pr->throttling.duty_width));

	if (!pr)
		return -EINVAL;

	/*
	 * Evaluate _PTC, _TSS and _TPC
	 * They must all be present or none of them can be used.
	 */
	if (acpi_processor_get_throttling_control(pr) ||
		acpi_processor_get_throttling_states(pr) ||
		acpi_processor_get_platform_limit(pr))
	{
		if (acpi_processor_get_fadt_info(pr))
			return 0;
		pr->throttling.acpi_processor_get_throttling =
		    &acpi_processor_get_throttling_fadt;
		pr->throttling.acpi_processor_set_throttling =
		    &acpi_processor_set_throttling_fadt;
	} else {
		pr->throttling.acpi_processor_get_throttling =
		    &acpi_processor_get_throttling_ptc;
		pr->throttling.acpi_processor_set_throttling =
		    &acpi_processor_set_throttling_ptc;
	}

	acpi_processor_get_tsd(pr);

	/*
	 * PIIX4 Errata: We don't support throttling on the original PIIX4.
	 * This shouldn't be an issue as few (if any) mobile systems ever
	 * used this part.
	 */
	if (errata.piix4.throttle) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "Throttling not supported on PIIX4 A- or B-step\n"));
		return 0;
	}

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
			  pr->throttling.state_count));

	pr->flags.throttling = 1;

	/*
	 * Disable throttling (if enabled).  We'll let subsequent policy (e.g.
	 * thermal) decide to lower performance if it so chooses, but for now
	 * we'll crank up the speed.
	 */

	result = acpi_processor_get_throttling(pr);
	if (result)
		goto end;

	if (pr->throttling.state) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "Disabling throttling (was T%d)\n",
				  pr->throttling.state));
		result = acpi_processor_set_throttling(pr, 0);
		if (result)
			goto end;
	}

      end:
	if (result)
		pr->flags.throttling = 0;

	return result;
}

/* proc interface */

static int acpi_processor_throttling_seq_show(struct seq_file *seq,
					      void *offset)
{
	struct acpi_processor *pr = seq->private;
	int i = 0;
	int result = 0;

	if (!pr)
		goto end;

	if (!(pr->throttling.state_count > 0)) {
		seq_puts(seq, "<not supported>\n");
		goto end;
	}

	result = acpi_processor_get_throttling(pr);

	if (result) {
		seq_puts(seq,
			 "Could not determine current throttling state.\n");
		goto end;
	}

	seq_printf(seq, "state count:             %d\n"
		   "active state:            T%d\n"
		   "state available: T%d to T%d\n",
		   pr->throttling.state_count, pr->throttling.state,
		   pr->throttling_platform_limit,
		   pr->throttling.state_count - 1);

	seq_puts(seq, "states:\n");
	if (pr->throttling.acpi_processor_get_throttling ==
			acpi_processor_get_throttling_fadt) {
		for (i = 0; i < pr->throttling.state_count; i++)
			seq_printf(seq, "   %cT%d:                  %02d%%\n",
				   (i == pr->throttling.state ? '*' : ' '), i,
				   (pr->throttling.states[i].performance ? pr->
				    throttling.states[i].performance / 10 : 0));
	} else {
		for (i = 0; i < pr->throttling.state_count; i++)
			seq_printf(seq, "   %cT%d:                  %02d%%\n",
				   (i == pr->throttling.state ? '*' : ' '), i,
				   (int)pr->throttling.states_tss[i].
				   freqpercentage);
	}

      end:
	return 0;
}

static int acpi_processor_throttling_open_fs(struct inode *inode,
					     struct file *file)
{
	return single_open(file, acpi_processor_throttling_seq_show,
			   PDE(inode)->data);
}

static ssize_t acpi_processor_write_throttling(struct file *file,
					       const char __user * buffer,
					       size_t count, loff_t * data)
{
	int result = 0;
	struct seq_file *m = file->private_data;
	struct acpi_processor *pr = m->private;
	char state_string[12] = { '\0' };

	if (!pr || (count > sizeof(state_string) - 1))
		return -EINVAL;

	if (copy_from_user(state_string, buffer, count))
		return -EFAULT;

	state_string[count] = '\0';

	result = acpi_processor_set_throttling(pr,
					       simple_strtoul(state_string,
							      NULL, 0));
	if (result)
		return result;

	return count;
}

struct file_operations acpi_processor_throttling_fops = {
	.open = acpi_processor_throttling_open_fs,
	.read = seq_read,
	.write = acpi_processor_write_throttling,
	.llseek = seq_lseek,
	.release = single_release,
};