Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / acpi / processor_perflib.c
blob85b32376dad7e7d133b68515a1c0baba5f96ffa0
1 /*
2 * processor_perflib.c - ACPI Processor P-States Library ($Revision: 71 $)
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
11 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or (at
16 * your option) any later version.
18 * This program is distributed in the hope that it will be useful, but
19 * WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 * General Public License for more details.
23 * You should have received a copy of the GNU General Public License along
24 * with this program; if not, write to the Free Software Foundation, Inc.,
25 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
29 #include <linux/kernel.h>
30 #include <linux/module.h>
31 #include <linux/init.h>
32 #include <linux/cpufreq.h>
33 #include <linux/slab.h>
35 #ifdef CONFIG_X86
36 #include <asm/cpufeature.h>
37 #endif
39 #include <acpi/acpi_bus.h>
40 #include <acpi/acpi_drivers.h>
41 #include <acpi/processor.h>
43 #define PREFIX "ACPI: "
45 #define ACPI_PROCESSOR_CLASS "processor"
46 #define ACPI_PROCESSOR_FILE_PERFORMANCE "performance"
47 #define _COMPONENT ACPI_PROCESSOR_COMPONENT
48 ACPI_MODULE_NAME("processor_perflib");
50 static DEFINE_MUTEX(performance_mutex);
53 * _PPC support is implemented as a CPUfreq policy notifier:
54 * This means each time a CPUfreq driver registered also with
55 * the ACPI core is asked to change the speed policy, the maximum
56 * value is adjusted so that it is within the platform limit.
58 * Also, when a new platform limit value is detected, the CPUfreq
59 * policy is adjusted accordingly.
62 /* ignore_ppc:
63 * -1 -> cpufreq low level drivers not initialized -> _PSS, etc. not called yet
64 * ignore _PPC
65 * 0 -> cpufreq low level drivers initialized -> consider _PPC values
66 * 1 -> ignore _PPC totally -> forced by user through boot param
68 static int ignore_ppc = -1;
69 module_param(ignore_ppc, int, 0644);
70 MODULE_PARM_DESC(ignore_ppc, "If the frequency of your machine gets wrongly" \
71 "limited by BIOS, this should help");
73 #define PPC_REGISTERED 1
74 #define PPC_IN_USE 2
76 static int acpi_processor_ppc_status;
78 static int acpi_processor_ppc_notifier(struct notifier_block *nb,
79 unsigned long event, void *data)
81 struct cpufreq_policy *policy = data;
82 struct acpi_processor *pr;
83 unsigned int ppc = 0;
85 if (event == CPUFREQ_START && ignore_ppc <= 0) {
86 ignore_ppc = 0;
87 return 0;
90 if (ignore_ppc)
91 return 0;
93 if (event != CPUFREQ_INCOMPATIBLE)
94 return 0;
96 mutex_lock(&performance_mutex);
98 pr = per_cpu(processors, policy->cpu);
99 if (!pr || !pr->performance)
100 goto out;
102 ppc = (unsigned int)pr->performance_platform_limit;
104 if (ppc >= pr->performance->state_count)
105 goto out;
107 cpufreq_verify_within_limits(policy, 0,
108 pr->performance->states[ppc].
109 core_frequency * 1000);
111 out:
112 mutex_unlock(&performance_mutex);
114 return 0;
117 static struct notifier_block acpi_ppc_notifier_block = {
118 .notifier_call = acpi_processor_ppc_notifier,
121 static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
123 acpi_status status = 0;
124 unsigned long long ppc = 0;
127 if (!pr)
128 return -EINVAL;
131 * _PPC indicates the maximum state currently supported by the platform
132 * (e.g. 0 = states 0..n; 1 = states 1..n; etc.
134 status = acpi_evaluate_integer(pr->handle, "_PPC", NULL, &ppc);
136 if (status != AE_NOT_FOUND)
137 acpi_processor_ppc_status |= PPC_IN_USE;
139 if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
140 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PPC"));
141 return -ENODEV;
144 pr_debug("CPU %d: _PPC is %d - frequency %s limited\n", pr->id,
145 (int)ppc, ppc ? "" : "not");
147 pr->performance_platform_limit = (int)ppc;
149 return 0;
152 #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
154 * acpi_processor_ppc_ost: Notify firmware the _PPC evaluation status
155 * @handle: ACPI processor handle
156 * @status: the status code of _PPC evaluation
157 * 0: success. OSPM is now using the performance state specificed.
158 * 1: failure. OSPM has not changed the number of P-states in use
160 static void acpi_processor_ppc_ost(acpi_handle handle, int status)
162 union acpi_object params[2] = {
163 {.type = ACPI_TYPE_INTEGER,},
164 {.type = ACPI_TYPE_INTEGER,},
166 struct acpi_object_list arg_list = {2, params};
167 acpi_handle temp;
169 params[0].integer.value = ACPI_PROCESSOR_NOTIFY_PERFORMANCE;
170 params[1].integer.value = status;
172 /* when there is no _OST , skip it */
173 if (ACPI_FAILURE(acpi_get_handle(handle, "_OST", &temp)))
174 return;
176 acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
177 return;
180 int acpi_processor_ppc_has_changed(struct acpi_processor *pr, int event_flag)
182 int ret;
184 if (ignore_ppc) {
186 * Only when it is notification event, the _OST object
187 * will be evaluated. Otherwise it is skipped.
189 if (event_flag)
190 acpi_processor_ppc_ost(pr->handle, 1);
191 return 0;
194 ret = acpi_processor_get_platform_limit(pr);
196 * Only when it is notification event, the _OST object
197 * will be evaluated. Otherwise it is skipped.
199 if (event_flag) {
200 if (ret < 0)
201 acpi_processor_ppc_ost(pr->handle, 1);
202 else
203 acpi_processor_ppc_ost(pr->handle, 0);
205 if (ret < 0)
206 return (ret);
207 else
208 return cpufreq_update_policy(pr->id);
211 int acpi_processor_get_bios_limit(int cpu, unsigned int *limit)
213 struct acpi_processor *pr;
215 pr = per_cpu(processors, cpu);
216 if (!pr || !pr->performance || !pr->performance->state_count)
217 return -ENODEV;
218 *limit = pr->performance->states[pr->performance_platform_limit].
219 core_frequency * 1000;
220 return 0;
222 EXPORT_SYMBOL(acpi_processor_get_bios_limit);
224 void acpi_processor_ppc_init(void)
226 if (!cpufreq_register_notifier
227 (&acpi_ppc_notifier_block, CPUFREQ_POLICY_NOTIFIER))
228 acpi_processor_ppc_status |= PPC_REGISTERED;
229 else
230 printk(KERN_DEBUG
231 "Warning: Processor Platform Limit not supported.\n");
234 void acpi_processor_ppc_exit(void)
236 if (acpi_processor_ppc_status & PPC_REGISTERED)
237 cpufreq_unregister_notifier(&acpi_ppc_notifier_block,
238 CPUFREQ_POLICY_NOTIFIER);
240 acpi_processor_ppc_status &= ~PPC_REGISTERED;
243 static int acpi_processor_get_performance_control(struct acpi_processor *pr)
245 int result = 0;
246 acpi_status status = 0;
247 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
248 union acpi_object *pct = NULL;
249 union acpi_object obj = { 0 };
252 status = acpi_evaluate_object(pr->handle, "_PCT", NULL, &buffer);
253 if (ACPI_FAILURE(status)) {
254 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PCT"));
255 return -ENODEV;
258 pct = (union acpi_object *)buffer.pointer;
259 if (!pct || (pct->type != ACPI_TYPE_PACKAGE)
260 || (pct->package.count != 2)) {
261 printk(KERN_ERR PREFIX "Invalid _PCT data\n");
262 result = -EFAULT;
263 goto end;
267 * control_register
270 obj = pct->package.elements[0];
272 if ((obj.type != ACPI_TYPE_BUFFER)
273 || (obj.buffer.length < sizeof(struct acpi_pct_register))
274 || (obj.buffer.pointer == NULL)) {
275 printk(KERN_ERR PREFIX "Invalid _PCT data (control_register)\n");
276 result = -EFAULT;
277 goto end;
279 memcpy(&pr->performance->control_register, obj.buffer.pointer,
280 sizeof(struct acpi_pct_register));
283 * status_register
286 obj = pct->package.elements[1];
288 if ((obj.type != ACPI_TYPE_BUFFER)
289 || (obj.buffer.length < sizeof(struct acpi_pct_register))
290 || (obj.buffer.pointer == NULL)) {
291 printk(KERN_ERR PREFIX "Invalid _PCT data (status_register)\n");
292 result = -EFAULT;
293 goto end;
296 memcpy(&pr->performance->status_register, obj.buffer.pointer,
297 sizeof(struct acpi_pct_register));
299 end:
300 kfree(buffer.pointer);
302 return result;
305 static int acpi_processor_get_performance_states(struct acpi_processor *pr)
307 int result = 0;
308 acpi_status status = AE_OK;
309 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
310 struct acpi_buffer format = { sizeof("NNNNNN"), "NNNNNN" };
311 struct acpi_buffer state = { 0, NULL };
312 union acpi_object *pss = NULL;
313 int i;
316 status = acpi_evaluate_object(pr->handle, "_PSS", NULL, &buffer);
317 if (ACPI_FAILURE(status)) {
318 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PSS"));
319 return -ENODEV;
322 pss = buffer.pointer;
323 if (!pss || (pss->type != ACPI_TYPE_PACKAGE)) {
324 printk(KERN_ERR PREFIX "Invalid _PSS data\n");
325 result = -EFAULT;
326 goto end;
329 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d performance states\n",
330 pss->package.count));
332 pr->performance->state_count = pss->package.count;
333 pr->performance->states =
334 kmalloc(sizeof(struct acpi_processor_px) * pss->package.count,
335 GFP_KERNEL);
336 if (!pr->performance->states) {
337 result = -ENOMEM;
338 goto end;
341 for (i = 0; i < pr->performance->state_count; i++) {
343 struct acpi_processor_px *px = &(pr->performance->states[i]);
345 state.length = sizeof(struct acpi_processor_px);
346 state.pointer = px;
348 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Extracting state %d\n", i));
350 status = acpi_extract_package(&(pss->package.elements[i]),
351 &format, &state);
352 if (ACPI_FAILURE(status)) {
353 ACPI_EXCEPTION((AE_INFO, status, "Invalid _PSS data"));
354 result = -EFAULT;
355 kfree(pr->performance->states);
356 goto end;
359 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
360 "State [%d]: core_frequency[%d] power[%d] transition_latency[%d] bus_master_latency[%d] control[0x%x] status[0x%x]\n",
362 (u32) px->core_frequency,
363 (u32) px->power,
364 (u32) px->transition_latency,
365 (u32) px->bus_master_latency,
366 (u32) px->control, (u32) px->status));
369 * Check that ACPI's u64 MHz will be valid as u32 KHz in cpufreq
371 if (!px->core_frequency ||
372 ((u32)(px->core_frequency * 1000) !=
373 (px->core_frequency * 1000))) {
374 printk(KERN_ERR FW_BUG PREFIX
375 "Invalid BIOS _PSS frequency: 0x%llx MHz\n",
376 px->core_frequency);
377 result = -EFAULT;
378 kfree(pr->performance->states);
379 goto end;
383 end:
384 kfree(buffer.pointer);
386 return result;
389 static int acpi_processor_get_performance_info(struct acpi_processor *pr)
391 int result = 0;
392 acpi_status status = AE_OK;
393 acpi_handle handle = NULL;
395 if (!pr || !pr->performance || !pr->handle)
396 return -EINVAL;
398 status = acpi_get_handle(pr->handle, "_PCT", &handle);
399 if (ACPI_FAILURE(status)) {
400 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
401 "ACPI-based processor performance control unavailable\n"));
402 return -ENODEV;
405 result = acpi_processor_get_performance_control(pr);
406 if (result)
407 goto update_bios;
409 result = acpi_processor_get_performance_states(pr);
410 if (result)
411 goto update_bios;
413 /* We need to call _PPC once when cpufreq starts */
414 if (ignore_ppc != 1)
415 result = acpi_processor_get_platform_limit(pr);
417 return result;
420 * Having _PPC but missing frequencies (_PSS, _PCT) is a very good hint that
421 * the BIOS is older than the CPU and does not know its frequencies
423 update_bios:
424 #ifdef CONFIG_X86
425 if (ACPI_SUCCESS(acpi_get_handle(pr->handle, "_PPC", &handle))){
426 if(boot_cpu_has(X86_FEATURE_EST))
427 printk(KERN_WARNING FW_BUG "BIOS needs update for CPU "
428 "frequency support\n");
430 #endif
431 return result;
434 int acpi_processor_notify_smm(struct module *calling_module)
436 acpi_status status;
437 static int is_done = 0;
440 if (!(acpi_processor_ppc_status & PPC_REGISTERED))
441 return -EBUSY;
443 if (!try_module_get(calling_module))
444 return -EINVAL;
446 /* is_done is set to negative if an error occurred,
447 * and to postitive if _no_ error occurred, but SMM
448 * was already notified. This avoids double notification
449 * which might lead to unexpected results...
451 if (is_done > 0) {
452 module_put(calling_module);
453 return 0;
454 } else if (is_done < 0) {
455 module_put(calling_module);
456 return is_done;
459 is_done = -EIO;
461 /* Can't write pstate_control to smi_command if either value is zero */
462 if ((!acpi_gbl_FADT.smi_command) || (!acpi_gbl_FADT.pstate_control)) {
463 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No SMI port or pstate_control\n"));
464 module_put(calling_module);
465 return 0;
468 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
469 "Writing pstate_control [0x%x] to smi_command [0x%x]\n",
470 acpi_gbl_FADT.pstate_control, acpi_gbl_FADT.smi_command));
472 status = acpi_os_write_port(acpi_gbl_FADT.smi_command,
473 (u32) acpi_gbl_FADT.pstate_control, 8);
474 if (ACPI_FAILURE(status)) {
475 ACPI_EXCEPTION((AE_INFO, status,
476 "Failed to write pstate_control [0x%x] to "
477 "smi_command [0x%x]", acpi_gbl_FADT.pstate_control,
478 acpi_gbl_FADT.smi_command));
479 module_put(calling_module);
480 return status;
483 /* Success. If there's no _PPC, we need to fear nothing, so
484 * we can allow the cpufreq driver to be rmmod'ed. */
485 is_done = 1;
487 if (!(acpi_processor_ppc_status & PPC_IN_USE))
488 module_put(calling_module);
490 return 0;
493 EXPORT_SYMBOL(acpi_processor_notify_smm);
495 static int acpi_processor_get_psd(struct acpi_processor *pr)
497 int result = 0;
498 acpi_status status = AE_OK;
499 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
500 struct acpi_buffer format = {sizeof("NNNNN"), "NNNNN"};
501 struct acpi_buffer state = {0, NULL};
502 union acpi_object *psd = NULL;
503 struct acpi_psd_package *pdomain;
505 status = acpi_evaluate_object(pr->handle, "_PSD", NULL, &buffer);
506 if (ACPI_FAILURE(status)) {
507 return -ENODEV;
510 psd = buffer.pointer;
511 if (!psd || (psd->type != ACPI_TYPE_PACKAGE)) {
512 printk(KERN_ERR PREFIX "Invalid _PSD data\n");
513 result = -EFAULT;
514 goto end;
517 if (psd->package.count != 1) {
518 printk(KERN_ERR PREFIX "Invalid _PSD data\n");
519 result = -EFAULT;
520 goto end;
523 pdomain = &(pr->performance->domain_info);
525 state.length = sizeof(struct acpi_psd_package);
526 state.pointer = pdomain;
528 status = acpi_extract_package(&(psd->package.elements[0]),
529 &format, &state);
530 if (ACPI_FAILURE(status)) {
531 printk(KERN_ERR PREFIX "Invalid _PSD data\n");
532 result = -EFAULT;
533 goto end;
536 if (pdomain->num_entries != ACPI_PSD_REV0_ENTRIES) {
537 printk(KERN_ERR PREFIX "Unknown _PSD:num_entries\n");
538 result = -EFAULT;
539 goto end;
542 if (pdomain->revision != ACPI_PSD_REV0_REVISION) {
543 printk(KERN_ERR PREFIX "Unknown _PSD:revision\n");
544 result = -EFAULT;
545 goto end;
548 if (pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ALL &&
549 pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ANY &&
550 pdomain->coord_type != DOMAIN_COORD_TYPE_HW_ALL) {
551 printk(KERN_ERR PREFIX "Invalid _PSD:coord_type\n");
552 result = -EFAULT;
553 goto end;
555 end:
556 kfree(buffer.pointer);
557 return result;
560 int acpi_processor_preregister_performance(
561 struct acpi_processor_performance __percpu *performance)
563 int count, count_target;
564 int retval = 0;
565 unsigned int i, j;
566 cpumask_var_t covered_cpus;
567 struct acpi_processor *pr;
568 struct acpi_psd_package *pdomain;
569 struct acpi_processor *match_pr;
570 struct acpi_psd_package *match_pdomain;
572 if (!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))
573 return -ENOMEM;
575 mutex_lock(&performance_mutex);
578 * Check if another driver has already registered, and abort before
579 * changing pr->performance if it has. Check input data as well.
581 for_each_possible_cpu(i) {
582 pr = per_cpu(processors, i);
583 if (!pr) {
584 /* Look only at processors in ACPI namespace */
585 continue;
588 if (pr->performance) {
589 retval = -EBUSY;
590 goto err_out;
593 if (!performance || !per_cpu_ptr(performance, i)) {
594 retval = -EINVAL;
595 goto err_out;
599 /* Call _PSD for all CPUs */
600 for_each_possible_cpu(i) {
601 pr = per_cpu(processors, i);
602 if (!pr)
603 continue;
605 pr->performance = per_cpu_ptr(performance, i);
606 cpumask_set_cpu(i, pr->performance->shared_cpu_map);
607 if (acpi_processor_get_psd(pr)) {
608 retval = -EINVAL;
609 continue;
612 if (retval)
613 goto err_ret;
616 * Now that we have _PSD data from all CPUs, lets setup P-state
617 * domain info.
619 for_each_possible_cpu(i) {
620 pr = per_cpu(processors, i);
621 if (!pr)
622 continue;
624 if (cpumask_test_cpu(i, covered_cpus))
625 continue;
627 pdomain = &(pr->performance->domain_info);
628 cpumask_set_cpu(i, pr->performance->shared_cpu_map);
629 cpumask_set_cpu(i, covered_cpus);
630 if (pdomain->num_processors <= 1)
631 continue;
633 /* Validate the Domain info */
634 count_target = pdomain->num_processors;
635 count = 1;
636 if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
637 pr->performance->shared_type = CPUFREQ_SHARED_TYPE_ALL;
638 else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
639 pr->performance->shared_type = CPUFREQ_SHARED_TYPE_HW;
640 else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
641 pr->performance->shared_type = CPUFREQ_SHARED_TYPE_ANY;
643 for_each_possible_cpu(j) {
644 if (i == j)
645 continue;
647 match_pr = per_cpu(processors, j);
648 if (!match_pr)
649 continue;
651 match_pdomain = &(match_pr->performance->domain_info);
652 if (match_pdomain->domain != pdomain->domain)
653 continue;
655 /* Here i and j are in the same domain */
657 if (match_pdomain->num_processors != count_target) {
658 retval = -EINVAL;
659 goto err_ret;
662 if (pdomain->coord_type != match_pdomain->coord_type) {
663 retval = -EINVAL;
664 goto err_ret;
667 cpumask_set_cpu(j, covered_cpus);
668 cpumask_set_cpu(j, pr->performance->shared_cpu_map);
669 count++;
672 for_each_possible_cpu(j) {
673 if (i == j)
674 continue;
676 match_pr = per_cpu(processors, j);
677 if (!match_pr)
678 continue;
680 match_pdomain = &(match_pr->performance->domain_info);
681 if (match_pdomain->domain != pdomain->domain)
682 continue;
684 match_pr->performance->shared_type =
685 pr->performance->shared_type;
686 cpumask_copy(match_pr->performance->shared_cpu_map,
687 pr->performance->shared_cpu_map);
691 err_ret:
692 for_each_possible_cpu(i) {
693 pr = per_cpu(processors, i);
694 if (!pr || !pr->performance)
695 continue;
697 /* Assume no coordination on any error parsing domain info */
698 if (retval) {
699 cpumask_clear(pr->performance->shared_cpu_map);
700 cpumask_set_cpu(i, pr->performance->shared_cpu_map);
701 pr->performance->shared_type = CPUFREQ_SHARED_TYPE_ALL;
703 pr->performance = NULL; /* Will be set for real in register */
706 err_out:
707 mutex_unlock(&performance_mutex);
708 free_cpumask_var(covered_cpus);
709 return retval;
711 EXPORT_SYMBOL(acpi_processor_preregister_performance);
714 acpi_processor_register_performance(struct acpi_processor_performance
715 *performance, unsigned int cpu)
717 struct acpi_processor *pr;
719 if (!(acpi_processor_ppc_status & PPC_REGISTERED))
720 return -EINVAL;
722 mutex_lock(&performance_mutex);
724 pr = per_cpu(processors, cpu);
725 if (!pr) {
726 mutex_unlock(&performance_mutex);
727 return -ENODEV;
730 if (pr->performance) {
731 mutex_unlock(&performance_mutex);
732 return -EBUSY;
735 WARN_ON(!performance);
737 pr->performance = performance;
739 if (acpi_processor_get_performance_info(pr)) {
740 pr->performance = NULL;
741 mutex_unlock(&performance_mutex);
742 return -EIO;
745 mutex_unlock(&performance_mutex);
746 return 0;
749 EXPORT_SYMBOL(acpi_processor_register_performance);
751 void
752 acpi_processor_unregister_performance(struct acpi_processor_performance
753 *performance, unsigned int cpu)
755 struct acpi_processor *pr;
757 mutex_lock(&performance_mutex);
759 pr = per_cpu(processors, cpu);
760 if (!pr) {
761 mutex_unlock(&performance_mutex);
762 return;
765 if (pr->performance)
766 kfree(pr->performance->states);
767 pr->performance = NULL;
769 mutex_unlock(&performance_mutex);
771 return;
774 EXPORT_SYMBOL(acpi_processor_unregister_performance);