ACPI: quiet ACPI Exceptions due to no _PTC or _TSS
[linux-3.10.git] / drivers / acpi / processor_throttling.c
1 /*
2  * processor_throttling.c - Throttling submodule of the ACPI processor driver
3  *
4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
6  *  Copyright (C) 2004       Dominik Brodowski <linux@brodo.de>
7  *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
8  *                      - Added processor hotplug support
9  *
10  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
11  *
12  *  This program is free software; you can redistribute it and/or modify
13  *  it under the terms of the GNU General Public License as published by
14  *  the Free Software Foundation; either version 2 of the License, or (at
15  *  your option) any later version.
16  *
17  *  This program is distributed in the hope that it will be useful, but
18  *  WITHOUT ANY WARRANTY; without even the implied warranty of
19  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
20  *  General Public License for more details.
21  *
22  *  You should have received a copy of the GNU General Public License along
23  *  with this program; if not, write to the Free Software Foundation, Inc.,
24  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
25  *
26  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
27  */
28
29 #include <linux/kernel.h>
30 #include <linux/module.h>
31 #include <linux/init.h>
32 #include <linux/cpufreq.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35
36 #include <asm/io.h>
37 #include <asm/uaccess.h>
38
39 #include <acpi/acpi_bus.h>
40 #include <acpi/processor.h>
41
42 #define ACPI_PROCESSOR_COMPONENT        0x01000000
43 #define ACPI_PROCESSOR_CLASS            "processor"
44 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
45 ACPI_MODULE_NAME("processor_throttling");
46
47 static int acpi_processor_get_throttling(struct acpi_processor *pr);
48 int acpi_processor_set_throttling(struct acpi_processor *pr, int state);
49
50 /*
51  * _TPC - Throttling Present Capabilities
52  */
53 static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
54 {
55         acpi_status status = 0;
56         unsigned long tpc = 0;
57
58         if (!pr)
59                 return -EINVAL;
60         status = acpi_evaluate_integer(pr->handle, "_TPC", NULL, &tpc);
61         if (ACPI_FAILURE(status)) {
62                 if (status != AE_NOT_FOUND) {
63                         ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TPC"));
64                 }
65                 return -ENODEV;
66         }
67         pr->throttling_platform_limit = (int)tpc;
68         return 0;
69 }
70
71 int acpi_processor_tstate_has_changed(struct acpi_processor *pr)
72 {
73         return acpi_processor_get_platform_limit(pr);
74 }
75
76 /*
77  * _PTC - Processor Throttling Control (and status) register location
78  */
79 static int acpi_processor_get_throttling_control(struct acpi_processor *pr)
80 {
81         int result = 0;
82         acpi_status status = 0;
83         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
84         union acpi_object *ptc = NULL;
85         union acpi_object obj = { 0 };
86
87         status = acpi_evaluate_object(pr->handle, "_PTC", NULL, &buffer);
88         if (ACPI_FAILURE(status)) {
89                 if (status != AE_NOT_FOUND) {
90                         ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PTC"));
91                 }
92                 return -ENODEV;
93         }
94
95         ptc = (union acpi_object *)buffer.pointer;
96         if (!ptc || (ptc->type != ACPI_TYPE_PACKAGE)
97             || (ptc->package.count != 2)) {
98                 printk(KERN_ERR PREFIX "Invalid _PTC data\n");
99                 result = -EFAULT;
100                 goto end;
101         }
102
103         /*
104          * control_register
105          */
106
107         obj = ptc->package.elements[0];
108
109         if ((obj.type != ACPI_TYPE_BUFFER)
110             || (obj.buffer.length < sizeof(struct acpi_ptc_register))
111             || (obj.buffer.pointer == NULL)) {
112                 printk(KERN_ERR PREFIX
113                        "Invalid _PTC data (control_register)\n");
114                 result = -EFAULT;
115                 goto end;
116         }
117         memcpy(&pr->throttling.control_register, obj.buffer.pointer,
118                sizeof(struct acpi_ptc_register));
119
120         /*
121          * status_register
122          */
123
124         obj = ptc->package.elements[1];
125
126         if ((obj.type != ACPI_TYPE_BUFFER)
127             || (obj.buffer.length < sizeof(struct acpi_ptc_register))
128             || (obj.buffer.pointer == NULL)) {
129                 printk(KERN_ERR PREFIX "Invalid _PTC data (status_register)\n");
130                 result = -EFAULT;
131                 goto end;
132         }
133
134         memcpy(&pr->throttling.status_register, obj.buffer.pointer,
135                sizeof(struct acpi_ptc_register));
136
137       end:
138         kfree(buffer.pointer);
139
140         return result;
141 }
142
143 /*
144  * _TSS - Throttling Supported States
145  */
146 static int acpi_processor_get_throttling_states(struct acpi_processor *pr)
147 {
148         int result = 0;
149         acpi_status status = AE_OK;
150         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
151         struct acpi_buffer format = { sizeof("NNNNN"), "NNNNN" };
152         struct acpi_buffer state = { 0, NULL };
153         union acpi_object *tss = NULL;
154         int i;
155
156         status = acpi_evaluate_object(pr->handle, "_TSS", NULL, &buffer);
157         if (ACPI_FAILURE(status)) {
158                 if (status != AE_NOT_FOUND) {
159                         ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSS"));
160                 }
161                 return -ENODEV;
162         }
163
164         tss = buffer.pointer;
165         if (!tss || (tss->type != ACPI_TYPE_PACKAGE)) {
166                 printk(KERN_ERR PREFIX "Invalid _TSS data\n");
167                 result = -EFAULT;
168                 goto end;
169         }
170
171         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
172                           tss->package.count));
173
174         pr->throttling.state_count = tss->package.count;
175         pr->throttling.states_tss =
176             kmalloc(sizeof(struct acpi_processor_tx_tss) * tss->package.count,
177                     GFP_KERNEL);
178         if (!pr->throttling.states_tss) {
179                 result = -ENOMEM;
180                 goto end;
181         }
182
183         for (i = 0; i < pr->throttling.state_count; i++) {
184
185                 struct acpi_processor_tx_tss *tx =
186                     (struct acpi_processor_tx_tss *)&(pr->throttling.
187                                                       states_tss[i]);
188
189                 state.length = sizeof(struct acpi_processor_tx_tss);
190                 state.pointer = tx;
191
192                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Extracting state %d\n", i));
193
194                 status = acpi_extract_package(&(tss->package.elements[i]),
195                                               &format, &state);
196                 if (ACPI_FAILURE(status)) {
197                         ACPI_EXCEPTION((AE_INFO, status, "Invalid _TSS data"));
198                         result = -EFAULT;
199                         kfree(pr->throttling.states_tss);
200                         goto end;
201                 }
202
203                 if (!tx->freqpercentage) {
204                         printk(KERN_ERR PREFIX
205                                "Invalid _TSS data: freq is zero\n");
206                         result = -EFAULT;
207                         kfree(pr->throttling.states_tss);
208                         goto end;
209                 }
210         }
211
212       end:
213         kfree(buffer.pointer);
214
215         return result;
216 }
217
218 /*
219  * _TSD - T-State Dependencies
220  */
221 static int acpi_processor_get_tsd(struct acpi_processor *pr)
222 {
223         int result = 0;
224         acpi_status status = AE_OK;
225         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
226         struct acpi_buffer format = { sizeof("NNNNN"), "NNNNN" };
227         struct acpi_buffer state = { 0, NULL };
228         union acpi_object *tsd = NULL;
229         struct acpi_tsd_package *pdomain;
230
231         status = acpi_evaluate_object(pr->handle, "_TSD", NULL, &buffer);
232         if (ACPI_FAILURE(status)) {
233                 if (status != AE_NOT_FOUND) {
234                         ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSD"));
235                 }
236                 return -ENODEV;
237         }
238
239         tsd = buffer.pointer;
240         if (!tsd || (tsd->type != ACPI_TYPE_PACKAGE)) {
241                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid _TSD data\n"));
242                 result = -EFAULT;
243                 goto end;
244         }
245
246         if (tsd->package.count != 1) {
247                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid _TSD data\n"));
248                 result = -EFAULT;
249                 goto end;
250         }
251
252         pdomain = &(pr->throttling.domain_info);
253
254         state.length = sizeof(struct acpi_tsd_package);
255         state.pointer = pdomain;
256
257         status = acpi_extract_package(&(tsd->package.elements[0]),
258                                       &format, &state);
259         if (ACPI_FAILURE(status)) {
260                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid _TSD data\n"));
261                 result = -EFAULT;
262                 goto end;
263         }
264
265         if (pdomain->num_entries != ACPI_TSD_REV0_ENTRIES) {
266                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Unknown _TSD:num_entries\n"));
267                 result = -EFAULT;
268                 goto end;
269         }
270
271         if (pdomain->revision != ACPI_TSD_REV0_REVISION) {
272                 ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Unknown _TSD:revision\n"));
273                 result = -EFAULT;
274                 goto end;
275         }
276
277       end:
278         kfree(buffer.pointer);
279         return result;
280 }
281
282 /* --------------------------------------------------------------------------
283                               Throttling Control
284    -------------------------------------------------------------------------- */
285 static int acpi_processor_get_throttling_fadt(struct acpi_processor *pr)
286 {
287         int state = 0;
288         u32 value = 0;
289         u32 duty_mask = 0;
290         u32 duty_value = 0;
291
292         if (!pr)
293                 return -EINVAL;
294
295         if (!pr->flags.throttling)
296                 return -ENODEV;
297
298         pr->throttling.state = 0;
299
300         duty_mask = pr->throttling.state_count - 1;
301
302         duty_mask <<= pr->throttling.duty_offset;
303
304         local_irq_disable();
305
306         value = inl(pr->throttling.address);
307
308         /*
309          * Compute the current throttling state when throttling is enabled
310          * (bit 4 is on).
311          */
312         if (value & 0x10) {
313                 duty_value = value & duty_mask;
314                 duty_value >>= pr->throttling.duty_offset;
315
316                 if (duty_value)
317                         state = pr->throttling.state_count - duty_value;
318         }
319
320         pr->throttling.state = state;
321
322         local_irq_enable();
323
324         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
325                           "Throttling state is T%d (%d%% throttling applied)\n",
326                           state, pr->throttling.states[state].performance));
327
328         return 0;
329 }
330
331 static int acpi_read_throttling_status(struct acpi_processor_throttling
332                                        *throttling)
333 {
334         int value = -1;
335         switch (throttling->status_register.space_id) {
336         case ACPI_ADR_SPACE_SYSTEM_IO:
337                 acpi_os_read_port((acpi_io_address) throttling->status_register.
338                                   address, &value,
339                                   (u32) throttling->status_register.bit_width *
340                                   8);
341                 break;
342         case ACPI_ADR_SPACE_FIXED_HARDWARE:
343                 printk(KERN_ERR PREFIX
344                        "HARDWARE addr space,NOT supported yet\n");
345                 break;
346         default:
347                 printk(KERN_ERR PREFIX "Unknown addr space %d\n",
348                        (u32) (throttling->status_register.space_id));
349         }
350         return value;
351 }
352
353 static int acpi_write_throttling_state(struct acpi_processor_throttling
354                                        *throttling, int value)
355 {
356         int ret = -1;
357
358         switch (throttling->control_register.space_id) {
359         case ACPI_ADR_SPACE_SYSTEM_IO:
360                 acpi_os_write_port((acpi_io_address) throttling->
361                                    control_register.address, value,
362                                    (u32) throttling->control_register.
363                                    bit_width * 8);
364                 ret = 0;
365                 break;
366         case ACPI_ADR_SPACE_FIXED_HARDWARE:
367                 printk(KERN_ERR PREFIX
368                        "HARDWARE addr space,NOT supported yet\n");
369                 break;
370         default:
371                 printk(KERN_ERR PREFIX "Unknown addr space %d\n",
372                        (u32) (throttling->control_register.space_id));
373         }
374         return ret;
375 }
376
377 static int acpi_get_throttling_state(struct acpi_processor *pr, int value)
378 {
379         int i;
380
381         for (i = 0; i < pr->throttling.state_count; i++) {
382                 struct acpi_processor_tx_tss *tx =
383                     (struct acpi_processor_tx_tss *)&(pr->throttling.
384                                                       states_tss[i]);
385                 if (tx->control == value)
386                         break;
387         }
388         if (i > pr->throttling.state_count)
389                 i = -1;
390         return i;
391 }
392
393 static int acpi_get_throttling_value(struct acpi_processor *pr, int state)
394 {
395         int value = -1;
396         if (state >= 0 && state <= pr->throttling.state_count) {
397                 struct acpi_processor_tx_tss *tx =
398                     (struct acpi_processor_tx_tss *)&(pr->throttling.
399                                                       states_tss[state]);
400                 value = tx->control;
401         }
402         return value;
403 }
404
405 static int acpi_processor_get_throttling_ptc(struct acpi_processor *pr)
406 {
407         int state = 0;
408         u32 value = 0;
409
410         if (!pr)
411                 return -EINVAL;
412
413         if (!pr->flags.throttling)
414                 return -ENODEV;
415
416         pr->throttling.state = 0;
417         local_irq_disable();
418         value = acpi_read_throttling_status(&pr->throttling);
419         if (value >= 0) {
420                 state = acpi_get_throttling_state(pr, value);
421                 pr->throttling.state = state;
422         }
423         local_irq_enable();
424
425         return 0;
426 }
427
428 static int acpi_processor_get_throttling(struct acpi_processor *pr)
429 {
430         return pr->throttling.acpi_processor_get_throttling(pr);
431 }
432
433 static int acpi_processor_set_throttling_fadt(struct acpi_processor *pr,
434                                               int state)
435 {
436         u32 value = 0;
437         u32 duty_mask = 0;
438         u32 duty_value = 0;
439
440         if (!pr)
441                 return -EINVAL;
442
443         if ((state < 0) || (state > (pr->throttling.state_count - 1)))
444                 return -EINVAL;
445
446         if (!pr->flags.throttling)
447                 return -ENODEV;
448
449         if (state == pr->throttling.state)
450                 return 0;
451
452         if (state < pr->throttling_platform_limit)
453                 return -EPERM;
454         /*
455          * Calculate the duty_value and duty_mask.
456          */
457         if (state) {
458                 duty_value = pr->throttling.state_count - state;
459
460                 duty_value <<= pr->throttling.duty_offset;
461
462                 /* Used to clear all duty_value bits */
463                 duty_mask = pr->throttling.state_count - 1;
464
465                 duty_mask <<= acpi_gbl_FADT.duty_offset;
466                 duty_mask = ~duty_mask;
467         }
468
469         local_irq_disable();
470
471         /*
472          * Disable throttling by writing a 0 to bit 4.  Note that we must
473          * turn it off before you can change the duty_value.
474          */
475         value = inl(pr->throttling.address);
476         if (value & 0x10) {
477                 value &= 0xFFFFFFEF;
478                 outl(value, pr->throttling.address);
479         }
480
481         /*
482          * Write the new duty_value and then enable throttling.  Note
483          * that a state value of 0 leaves throttling disabled.
484          */
485         if (state) {
486                 value &= duty_mask;
487                 value |= duty_value;
488                 outl(value, pr->throttling.address);
489
490                 value |= 0x00000010;
491                 outl(value, pr->throttling.address);
492         }
493
494         pr->throttling.state = state;
495
496         local_irq_enable();
497
498         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
499                           "Throttling state set to T%d (%d%%)\n", state,
500                           (pr->throttling.states[state].performance ? pr->
501                            throttling.states[state].performance / 10 : 0)));
502
503         return 0;
504 }
505
506 static int acpi_processor_set_throttling_ptc(struct acpi_processor *pr,
507                                              int state)
508 {
509         u32 value = 0;
510
511         if (!pr)
512                 return -EINVAL;
513
514         if ((state < 0) || (state > (pr->throttling.state_count - 1)))
515                 return -EINVAL;
516
517         if (!pr->flags.throttling)
518                 return -ENODEV;
519
520         if (state == pr->throttling.state)
521                 return 0;
522
523         if (state < pr->throttling_platform_limit)
524                 return -EPERM;
525
526         local_irq_disable();
527
528         value = acpi_get_throttling_value(pr, state);
529         if (value >= 0) {
530                 acpi_write_throttling_state(&pr->throttling, value);
531                 pr->throttling.state = state;
532         }
533         local_irq_enable();
534
535         return 0;
536 }
537
538 int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
539 {
540         return pr->throttling.acpi_processor_set_throttling(pr, state);
541 }
542
543 int acpi_processor_get_throttling_info(struct acpi_processor *pr)
544 {
545         int result = 0;
546         int step = 0;
547         int i = 0;
548
549         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
550                           "pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
551                           pr->throttling.address,
552                           pr->throttling.duty_offset,
553                           pr->throttling.duty_width));
554
555         if (!pr)
556                 return -EINVAL;
557
558         /*
559          * Evaluate _PTC, _TSS and _TPC
560          * They must all be present or none of them can be used.
561          */
562         if (acpi_processor_get_throttling_control(pr) ||
563                 acpi_processor_get_throttling_states(pr) ||
564                 acpi_processor_get_platform_limit(pr))
565         {
566                 pr->throttling.acpi_processor_get_throttling =
567                     &acpi_processor_get_throttling_fadt;
568                 pr->throttling.acpi_processor_set_throttling =
569                     &acpi_processor_set_throttling_fadt;
570         } else {
571                 pr->throttling.acpi_processor_get_throttling =
572                     &acpi_processor_get_throttling_ptc;
573                 pr->throttling.acpi_processor_set_throttling =
574                     &acpi_processor_set_throttling_ptc;
575         }
576
577         acpi_processor_get_tsd(pr);
578
579         if (!pr->throttling.address) {
580                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
581                 return 0;
582         } else if (!pr->throttling.duty_width) {
583                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
584                 return 0;
585         }
586         /* TBD: Support duty_cycle values that span bit 4. */
587         else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) {
588                 printk(KERN_WARNING PREFIX "duty_cycle spans bit 4\n");
589                 return 0;
590         }
591
592         /*
593          * PIIX4 Errata: We don't support throttling on the original PIIX4.
594          * This shouldn't be an issue as few (if any) mobile systems ever
595          * used this part.
596          */
597         if (errata.piix4.throttle) {
598                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
599                                   "Throttling not supported on PIIX4 A- or B-step\n"));
600                 return 0;
601         }
602
603         pr->throttling.state_count = 1 << acpi_gbl_FADT.duty_width;
604
605         /*
606          * Compute state values. Note that throttling displays a linear power/
607          * performance relationship (at 50% performance the CPU will consume
608          * 50% power).  Values are in 1/10th of a percent to preserve accuracy.
609          */
610
611         step = (1000 / pr->throttling.state_count);
612
613         for (i = 0; i < pr->throttling.state_count; i++) {
614                 pr->throttling.states[i].performance = step * i;
615                 pr->throttling.states[i].power = step * i;
616         }
617
618         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
619                           pr->throttling.state_count));
620
621         pr->flags.throttling = 1;
622
623         /*
624          * Disable throttling (if enabled).  We'll let subsequent policy (e.g.
625          * thermal) decide to lower performance if it so chooses, but for now
626          * we'll crank up the speed.
627          */
628
629         result = acpi_processor_get_throttling(pr);
630         if (result)
631                 goto end;
632
633         if (pr->throttling.state) {
634                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
635                                   "Disabling throttling (was T%d)\n",
636                                   pr->throttling.state));
637                 result = acpi_processor_set_throttling(pr, 0);
638                 if (result)
639                         goto end;
640         }
641
642       end:
643         if (result)
644                 pr->flags.throttling = 0;
645
646         return result;
647 }
648
649 /* proc interface */
650
651 static int acpi_processor_throttling_seq_show(struct seq_file *seq,
652                                               void *offset)
653 {
654         struct acpi_processor *pr = seq->private;
655         int i = 0;
656         int result = 0;
657
658         if (!pr)
659                 goto end;
660
661         if (!(pr->throttling.state_count > 0)) {
662                 seq_puts(seq, "<not supported>\n");
663                 goto end;
664         }
665
666         result = acpi_processor_get_throttling(pr);
667
668         if (result) {
669                 seq_puts(seq,
670                          "Could not determine current throttling state.\n");
671                 goto end;
672         }
673
674         seq_printf(seq, "state count:             %d\n"
675                    "active state:            T%d\n"
676                    "state available: T%d to T%d\n",
677                    pr->throttling.state_count, pr->throttling.state,
678                    pr->throttling_platform_limit,
679                    pr->throttling.state_count - 1);
680
681         seq_puts(seq, "states:\n");
682         if (pr->throttling.acpi_processor_get_throttling ==
683                         acpi_processor_get_throttling_fadt) {
684                 for (i = 0; i < pr->throttling.state_count; i++)
685                         seq_printf(seq, "   %cT%d:                  %02d%%\n",
686                                    (i == pr->throttling.state ? '*' : ' '), i,
687                                    (pr->throttling.states[i].performance ? pr->
688                                     throttling.states[i].performance / 10 : 0));
689         } else {
690                 for (i = 0; i < pr->throttling.state_count; i++)
691                         seq_printf(seq, "   %cT%d:                  %02d%%\n",
692                                    (i == pr->throttling.state ? '*' : ' '), i,
693                                    (int)pr->throttling.states_tss[i].
694                                    freqpercentage);
695         }
696
697       end:
698         return 0;
699 }
700
701 static int acpi_processor_throttling_open_fs(struct inode *inode,
702                                              struct file *file)
703 {
704         return single_open(file, acpi_processor_throttling_seq_show,
705                            PDE(inode)->data);
706 }
707
708 static ssize_t acpi_processor_write_throttling(struct file *file,
709                                                const char __user * buffer,
710                                                size_t count, loff_t * data)
711 {
712         int result = 0;
713         struct seq_file *m = file->private_data;
714         struct acpi_processor *pr = m->private;
715         char state_string[12] = { '\0' };
716
717         if (!pr || (count > sizeof(state_string) - 1))
718                 return -EINVAL;
719
720         if (copy_from_user(state_string, buffer, count))
721                 return -EFAULT;
722
723         state_string[count] = '\0';
724
725         result = acpi_processor_set_throttling(pr,
726                                                simple_strtoul(state_string,
727                                                               NULL, 0));
728         if (result)
729                 return result;
730
731         return count;
732 }
733
734 struct file_operations acpi_processor_throttling_fops = {
735         .open = acpi_processor_throttling_open_fs,
736         .read = seq_read,
737         .write = acpi_processor_write_throttling,
738         .llseek = seq_lseek,
739         .release = single_release,
740 };