2 * linux/drivers/cpufreq/cpufreq.c
4 * Copyright (C) 2001 Russell King
5 * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
6 * (C) 2013 Viresh Kumar <viresh.kumar@linaro.org>
8 * Oct 2005 - Ashok Raj <ashok.raj@intel.com>
9 * Added handling for CPU hotplug
10 * Feb 2006 - Jacob Shin <jacob.shin@amd.com>
11 * Fix handling for CPU hotplug -- affected CPUs
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License version 2 as
15 * published by the Free Software Foundation.
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 #include <linux/cpu.h>
21 #include <linux/cpufreq.h>
22 #include <linux/delay.h>
23 #include <linux/device.h>
24 #include <linux/init.h>
25 #include <linux/kernel_stat.h>
26 #include <linux/module.h>
27 #include <linux/mutex.h>
28 #include <linux/slab.h>
29 #include <linux/suspend.h>
30 #include <linux/tick.h>
31 #include <trace/events/power.h>
34 * The "cpufreq driver" - the arch- or hardware-dependent low
35 * level driver of CPUFreq support, and its spinlock. This lock
36 * also protects the cpufreq_cpu_data array.
38 static struct cpufreq_driver *cpufreq_driver;
39 static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
40 static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data_fallback);
41 static DEFINE_RWLOCK(cpufreq_driver_lock);
42 DEFINE_MUTEX(cpufreq_governor_lock);
43 static LIST_HEAD(cpufreq_policy_list);
45 /* This one keeps track of the previously set governor of a removed CPU */
46 static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
48 /* Flag to suspend/resume CPUFreq governors */
49 static bool cpufreq_suspended;
51 static inline bool has_target(void)
53 return cpufreq_driver->target_index || cpufreq_driver->target;
57 * rwsem to guarantee that cpufreq driver module doesn't unload during critical
60 static DECLARE_RWSEM(cpufreq_rwsem);
62 /* internal prototypes */
63 static int __cpufreq_governor(struct cpufreq_policy *policy,
65 static unsigned int __cpufreq_get(unsigned int cpu);
66 static void handle_update(struct work_struct *work);
69 * Two notifier lists: the "policy" list is involved in the
70 * validation process for a new CPU frequency policy; the
71 * "transition" list for kernel code that needs to handle
72 * changes to devices when the CPU clock speed changes.
73 * The mutex locks both lists.
75 static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
76 static struct srcu_notifier_head cpufreq_transition_notifier_list;
78 static bool init_cpufreq_transition_notifier_list_called;
79 static int __init init_cpufreq_transition_notifier_list(void)
81 srcu_init_notifier_head(&cpufreq_transition_notifier_list);
82 init_cpufreq_transition_notifier_list_called = true;
85 pure_initcall(init_cpufreq_transition_notifier_list);
87 static int off __read_mostly;
88 static int cpufreq_disabled(void)
92 void disable_cpufreq(void)
96 static LIST_HEAD(cpufreq_governor_list);
97 static DEFINE_MUTEX(cpufreq_governor_mutex);
99 bool have_governor_per_policy(void)
101 return !!(cpufreq_driver->flags & CPUFREQ_HAVE_GOVERNOR_PER_POLICY);
103 EXPORT_SYMBOL_GPL(have_governor_per_policy);
105 struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy)
107 if (have_governor_per_policy())
108 return &policy->kobj;
110 return cpufreq_global_kobject;
112 EXPORT_SYMBOL_GPL(get_governor_parent_kobj);
114 static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
120 cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
122 busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
123 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
124 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
125 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
126 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
127 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
129 idle_time = cur_wall_time - busy_time;
131 *wall = cputime_to_usecs(cur_wall_time);
133 return cputime_to_usecs(idle_time);
136 u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy)
138 u64 idle_time = get_cpu_idle_time_us(cpu, io_busy ? wall : NULL);
140 if (idle_time == -1ULL)
141 return get_cpu_idle_time_jiffy(cpu, wall);
143 idle_time += get_cpu_iowait_time_us(cpu, wall);
147 EXPORT_SYMBOL_GPL(get_cpu_idle_time);
150 * This is a generic cpufreq init() routine which can be used by cpufreq
151 * drivers of SMP systems. It will do following:
152 * - validate & show freq table passed
153 * - set policies transition latency
154 * - policy->cpus with all possible CPUs
156 int cpufreq_generic_init(struct cpufreq_policy *policy,
157 struct cpufreq_frequency_table *table,
158 unsigned int transition_latency)
162 ret = cpufreq_table_validate_and_show(policy, table);
164 pr_err("%s: invalid frequency table: %d\n", __func__, ret);
168 policy->cpuinfo.transition_latency = transition_latency;
171 * The driver only supports the SMP configuartion where all processors
172 * share the clock and voltage and clock.
174 cpumask_setall(policy->cpus);
178 EXPORT_SYMBOL_GPL(cpufreq_generic_init);
180 unsigned int cpufreq_generic_get(unsigned int cpu)
182 struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
184 if (!policy || IS_ERR(policy->clk)) {
185 pr_err("%s: No %s associated to cpu: %d\n",
186 __func__, policy ? "clk" : "policy", cpu);
190 return clk_get_rate(policy->clk) / 1000;
192 EXPORT_SYMBOL_GPL(cpufreq_generic_get);
194 /* Only for cpufreq core internal use */
195 struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu)
197 return per_cpu(cpufreq_cpu_data, cpu);
200 struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
202 struct cpufreq_policy *policy = NULL;
205 if (cpufreq_disabled() || (cpu >= nr_cpu_ids))
208 if (!down_read_trylock(&cpufreq_rwsem))
211 /* get the cpufreq driver */
212 read_lock_irqsave(&cpufreq_driver_lock, flags);
214 if (cpufreq_driver) {
216 policy = per_cpu(cpufreq_cpu_data, cpu);
218 kobject_get(&policy->kobj);
221 read_unlock_irqrestore(&cpufreq_driver_lock, flags);
224 up_read(&cpufreq_rwsem);
228 EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
230 void cpufreq_cpu_put(struct cpufreq_policy *policy)
232 if (cpufreq_disabled())
235 kobject_put(&policy->kobj);
236 up_read(&cpufreq_rwsem);
238 EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
240 /*********************************************************************
241 * EXTERNALLY AFFECTING FREQUENCY CHANGES *
242 *********************************************************************/
245 * adjust_jiffies - adjust the system "loops_per_jiffy"
247 * This function alters the system "loops_per_jiffy" for the clock
248 * speed change. Note that loops_per_jiffy cannot be updated on SMP
249 * systems as each CPU might be scaled differently. So, use the arch
250 * per-CPU loops_per_jiffy value wherever possible.
253 static unsigned long l_p_j_ref;
254 static unsigned int l_p_j_ref_freq;
256 static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
258 if (ci->flags & CPUFREQ_CONST_LOOPS)
261 if (!l_p_j_ref_freq) {
262 l_p_j_ref = loops_per_jiffy;
263 l_p_j_ref_freq = ci->old;
264 pr_debug("saving %lu as reference value for loops_per_jiffy; freq is %u kHz\n",
265 l_p_j_ref, l_p_j_ref_freq);
267 if (val == CPUFREQ_POSTCHANGE && ci->old != ci->new) {
268 loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq,
270 pr_debug("scaling loops_per_jiffy to %lu for frequency %u kHz\n",
271 loops_per_jiffy, ci->new);
275 static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
281 static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
282 struct cpufreq_freqs *freqs, unsigned int state)
284 BUG_ON(irqs_disabled());
286 if (cpufreq_disabled())
289 freqs->flags = cpufreq_driver->flags;
290 pr_debug("notification %u of frequency transition to %u kHz\n",
295 case CPUFREQ_PRECHANGE:
296 /* detect if the driver reported a value as "old frequency"
297 * which is not equal to what the cpufreq core thinks is
300 if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
301 if ((policy) && (policy->cpu == freqs->cpu) &&
302 (policy->cur) && (policy->cur != freqs->old)) {
303 pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
304 freqs->old, policy->cur);
305 freqs->old = policy->cur;
308 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
309 CPUFREQ_PRECHANGE, freqs);
310 adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
313 case CPUFREQ_POSTCHANGE:
314 adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
315 pr_debug("FREQ: %lu - CPU: %lu\n",
316 (unsigned long)freqs->new, (unsigned long)freqs->cpu);
317 trace_cpu_frequency(freqs->new, freqs->cpu);
318 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
319 CPUFREQ_POSTCHANGE, freqs);
320 if (likely(policy) && likely(policy->cpu == freqs->cpu))
321 policy->cur = freqs->new;
327 * cpufreq_notify_transition - call notifier chain and adjust_jiffies
328 * on frequency transition.
330 * This function calls the transition notifiers and the "adjust_jiffies"
331 * function. It is called twice on all CPU frequency changes that have
334 static void cpufreq_notify_transition(struct cpufreq_policy *policy,
335 struct cpufreq_freqs *freqs, unsigned int state)
337 for_each_cpu(freqs->cpu, policy->cpus)
338 __cpufreq_notify_transition(policy, freqs, state);
341 /* Do post notifications when there are chances that transition has failed */
342 static void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
343 struct cpufreq_freqs *freqs, int transition_failed)
345 cpufreq_notify_transition(policy, freqs, CPUFREQ_POSTCHANGE);
346 if (!transition_failed)
349 swap(freqs->old, freqs->new);
350 cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
351 cpufreq_notify_transition(policy, freqs, CPUFREQ_POSTCHANGE);
354 void cpufreq_freq_transition_begin(struct cpufreq_policy *policy,
355 struct cpufreq_freqs *freqs)
359 * Catch double invocations of _begin() which lead to self-deadlock.
360 * ASYNC_NOTIFICATION drivers are left out because the cpufreq core
361 * doesn't invoke _begin() on their behalf, and hence the chances of
362 * double invocations are very low. Moreover, there are scenarios
363 * where these checks can emit false-positive warnings in these
364 * drivers; so we avoid that by skipping them altogether.
366 WARN_ON(!(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION)
367 && current == policy->transition_task);
370 wait_event(policy->transition_wait, !policy->transition_ongoing);
372 spin_lock(&policy->transition_lock);
374 if (unlikely(policy->transition_ongoing)) {
375 spin_unlock(&policy->transition_lock);
379 policy->transition_ongoing = true;
380 policy->transition_task = current;
382 spin_unlock(&policy->transition_lock);
384 cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
386 EXPORT_SYMBOL_GPL(cpufreq_freq_transition_begin);
388 void cpufreq_freq_transition_end(struct cpufreq_policy *policy,
389 struct cpufreq_freqs *freqs, int transition_failed)
391 if (unlikely(WARN_ON(!policy->transition_ongoing)))
394 cpufreq_notify_post_transition(policy, freqs, transition_failed);
396 policy->transition_ongoing = false;
397 policy->transition_task = NULL;
399 wake_up(&policy->transition_wait);
401 EXPORT_SYMBOL_GPL(cpufreq_freq_transition_end);
404 /*********************************************************************
406 *********************************************************************/
407 static ssize_t show_boost(struct kobject *kobj,
408 struct attribute *attr, char *buf)
410 return sprintf(buf, "%d\n", cpufreq_driver->boost_enabled);
413 static ssize_t store_boost(struct kobject *kobj, struct attribute *attr,
414 const char *buf, size_t count)
418 ret = sscanf(buf, "%d", &enable);
419 if (ret != 1 || enable < 0 || enable > 1)
422 if (cpufreq_boost_trigger_state(enable)) {
423 pr_err("%s: Cannot %s BOOST!\n",
424 __func__, enable ? "enable" : "disable");
428 pr_debug("%s: cpufreq BOOST %s\n",
429 __func__, enable ? "enabled" : "disabled");
433 define_one_global_rw(boost);
435 static struct cpufreq_governor *__find_governor(const char *str_governor)
437 struct cpufreq_governor *t;
439 list_for_each_entry(t, &cpufreq_governor_list, governor_list)
440 if (!strncasecmp(str_governor, t->name, CPUFREQ_NAME_LEN))
447 * cpufreq_parse_governor - parse a governor string
449 static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
450 struct cpufreq_governor **governor)
457 if (cpufreq_driver->setpolicy) {
458 if (!strncasecmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
459 *policy = CPUFREQ_POLICY_PERFORMANCE;
461 } else if (!strncasecmp(str_governor, "powersave",
463 *policy = CPUFREQ_POLICY_POWERSAVE;
466 } else if (has_target()) {
467 struct cpufreq_governor *t;
469 mutex_lock(&cpufreq_governor_mutex);
471 t = __find_governor(str_governor);
476 mutex_unlock(&cpufreq_governor_mutex);
477 ret = request_module("cpufreq_%s", str_governor);
478 mutex_lock(&cpufreq_governor_mutex);
481 t = __find_governor(str_governor);
489 mutex_unlock(&cpufreq_governor_mutex);
496 * cpufreq_per_cpu_attr_read() / show_##file_name() -
497 * print out cpufreq information
499 * Write out information from cpufreq_driver->policy[cpu]; object must be
503 #define show_one(file_name, object) \
504 static ssize_t show_##file_name \
505 (struct cpufreq_policy *policy, char *buf) \
507 return sprintf(buf, "%u\n", policy->object); \
510 show_one(cpuinfo_min_freq, cpuinfo.min_freq);
511 show_one(cpuinfo_max_freq, cpuinfo.max_freq);
512 show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
513 show_one(scaling_min_freq, min);
514 show_one(scaling_max_freq, max);
516 static ssize_t show_scaling_cur_freq(
517 struct cpufreq_policy *policy, char *buf)
521 if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get)
522 ret = sprintf(buf, "%u\n", cpufreq_driver->get(policy->cpu));
524 ret = sprintf(buf, "%u\n", policy->cur);
528 static int cpufreq_set_policy(struct cpufreq_policy *policy,
529 struct cpufreq_policy *new_policy);
532 * cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
534 #define store_one(file_name, object) \
535 static ssize_t store_##file_name \
536 (struct cpufreq_policy *policy, const char *buf, size_t count) \
539 struct cpufreq_policy new_policy; \
541 ret = cpufreq_get_policy(&new_policy, policy->cpu); \
545 ret = sscanf(buf, "%u", &new_policy.object); \
549 temp = new_policy.object; \
550 ret = cpufreq_set_policy(policy, &new_policy); \
552 policy->user_policy.object = temp; \
554 return ret ? ret : count; \
557 store_one(scaling_min_freq, min);
558 store_one(scaling_max_freq, max);
561 * show_cpuinfo_cur_freq - current CPU frequency as detected by hardware
563 static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
566 unsigned int cur_freq = __cpufreq_get(policy->cpu);
568 return sprintf(buf, "<unknown>");
569 return sprintf(buf, "%u\n", cur_freq);
573 * show_scaling_governor - show the current policy for the specified CPU
575 static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf)
577 if (policy->policy == CPUFREQ_POLICY_POWERSAVE)
578 return sprintf(buf, "powersave\n");
579 else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
580 return sprintf(buf, "performance\n");
581 else if (policy->governor)
582 return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n",
583 policy->governor->name);
588 * store_scaling_governor - store policy for the specified CPU
590 static ssize_t store_scaling_governor(struct cpufreq_policy *policy,
591 const char *buf, size_t count)
594 char str_governor[16];
595 struct cpufreq_policy new_policy;
597 ret = cpufreq_get_policy(&new_policy, policy->cpu);
601 ret = sscanf(buf, "%15s", str_governor);
605 if (cpufreq_parse_governor(str_governor, &new_policy.policy,
606 &new_policy.governor))
609 ret = cpufreq_set_policy(policy, &new_policy);
611 policy->user_policy.policy = policy->policy;
612 policy->user_policy.governor = policy->governor;
621 * show_scaling_driver - show the cpufreq driver currently loaded
623 static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
625 return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n", cpufreq_driver->name);
629 * show_scaling_available_governors - show the available CPUfreq governors
631 static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
635 struct cpufreq_governor *t;
638 i += sprintf(buf, "performance powersave");
642 list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
643 if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
644 - (CPUFREQ_NAME_LEN + 2)))
646 i += scnprintf(&buf[i], CPUFREQ_NAME_PLEN, "%s ", t->name);
649 i += sprintf(&buf[i], "\n");
653 ssize_t cpufreq_show_cpus(const struct cpumask *mask, char *buf)
658 for_each_cpu(cpu, mask) {
660 i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), " ");
661 i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u", cpu);
662 if (i >= (PAGE_SIZE - 5))
665 i += sprintf(&buf[i], "\n");
668 EXPORT_SYMBOL_GPL(cpufreq_show_cpus);
671 * show_related_cpus - show the CPUs affected by each transition even if
672 * hw coordination is in use
674 static ssize_t show_related_cpus(struct cpufreq_policy *policy, char *buf)
676 return cpufreq_show_cpus(policy->related_cpus, buf);
680 * show_affected_cpus - show the CPUs affected by each transition
682 static ssize_t show_affected_cpus(struct cpufreq_policy *policy, char *buf)
684 return cpufreq_show_cpus(policy->cpus, buf);
687 static ssize_t store_scaling_setspeed(struct cpufreq_policy *policy,
688 const char *buf, size_t count)
690 unsigned int freq = 0;
693 if (!policy->governor || !policy->governor->store_setspeed)
696 ret = sscanf(buf, "%u", &freq);
700 policy->governor->store_setspeed(policy, freq);
705 static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
707 if (!policy->governor || !policy->governor->show_setspeed)
708 return sprintf(buf, "<unsupported>\n");
710 return policy->governor->show_setspeed(policy, buf);
714 * show_bios_limit - show the current cpufreq HW/BIOS limitation
716 static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
720 if (cpufreq_driver->bios_limit) {
721 ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
723 return sprintf(buf, "%u\n", limit);
725 return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
728 cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);
729 cpufreq_freq_attr_ro(cpuinfo_min_freq);
730 cpufreq_freq_attr_ro(cpuinfo_max_freq);
731 cpufreq_freq_attr_ro(cpuinfo_transition_latency);
732 cpufreq_freq_attr_ro(scaling_available_governors);
733 cpufreq_freq_attr_ro(scaling_driver);
734 cpufreq_freq_attr_ro(scaling_cur_freq);
735 cpufreq_freq_attr_ro(bios_limit);
736 cpufreq_freq_attr_ro(related_cpus);
737 cpufreq_freq_attr_ro(affected_cpus);
738 cpufreq_freq_attr_rw(scaling_min_freq);
739 cpufreq_freq_attr_rw(scaling_max_freq);
740 cpufreq_freq_attr_rw(scaling_governor);
741 cpufreq_freq_attr_rw(scaling_setspeed);
743 static struct attribute *default_attrs[] = {
744 &cpuinfo_min_freq.attr,
745 &cpuinfo_max_freq.attr,
746 &cpuinfo_transition_latency.attr,
747 &scaling_min_freq.attr,
748 &scaling_max_freq.attr,
751 &scaling_governor.attr,
752 &scaling_driver.attr,
753 &scaling_available_governors.attr,
754 &scaling_setspeed.attr,
758 #define to_policy(k) container_of(k, struct cpufreq_policy, kobj)
759 #define to_attr(a) container_of(a, struct freq_attr, attr)
761 static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
763 struct cpufreq_policy *policy = to_policy(kobj);
764 struct freq_attr *fattr = to_attr(attr);
767 if (!down_read_trylock(&cpufreq_rwsem))
770 down_read(&policy->rwsem);
773 ret = fattr->show(policy, buf);
777 up_read(&policy->rwsem);
778 up_read(&cpufreq_rwsem);
783 static ssize_t store(struct kobject *kobj, struct attribute *attr,
784 const char *buf, size_t count)
786 struct cpufreq_policy *policy = to_policy(kobj);
787 struct freq_attr *fattr = to_attr(attr);
788 ssize_t ret = -EINVAL;
792 if (!cpu_online(policy->cpu))
795 if (!down_read_trylock(&cpufreq_rwsem))
798 down_write(&policy->rwsem);
801 ret = fattr->store(policy, buf, count);
805 up_write(&policy->rwsem);
807 up_read(&cpufreq_rwsem);
814 static void cpufreq_sysfs_release(struct kobject *kobj)
816 struct cpufreq_policy *policy = to_policy(kobj);
817 pr_debug("last reference is dropped\n");
818 complete(&policy->kobj_unregister);
821 static const struct sysfs_ops sysfs_ops = {
826 static struct kobj_type ktype_cpufreq = {
827 .sysfs_ops = &sysfs_ops,
828 .default_attrs = default_attrs,
829 .release = cpufreq_sysfs_release,
832 struct kobject *cpufreq_global_kobject;
833 EXPORT_SYMBOL(cpufreq_global_kobject);
835 static int cpufreq_global_kobject_usage;
837 int cpufreq_get_global_kobject(void)
839 if (!cpufreq_global_kobject_usage++)
840 return kobject_add(cpufreq_global_kobject,
841 &cpu_subsys.dev_root->kobj, "%s", "cpufreq");
845 EXPORT_SYMBOL(cpufreq_get_global_kobject);
847 void cpufreq_put_global_kobject(void)
849 if (!--cpufreq_global_kobject_usage)
850 kobject_del(cpufreq_global_kobject);
852 EXPORT_SYMBOL(cpufreq_put_global_kobject);
854 int cpufreq_sysfs_create_file(const struct attribute *attr)
856 int ret = cpufreq_get_global_kobject();
859 ret = sysfs_create_file(cpufreq_global_kobject, attr);
861 cpufreq_put_global_kobject();
866 EXPORT_SYMBOL(cpufreq_sysfs_create_file);
868 void cpufreq_sysfs_remove_file(const struct attribute *attr)
870 sysfs_remove_file(cpufreq_global_kobject, attr);
871 cpufreq_put_global_kobject();
873 EXPORT_SYMBOL(cpufreq_sysfs_remove_file);
875 /* symlink affected CPUs */
876 static int cpufreq_add_dev_symlink(struct cpufreq_policy *policy)
881 for_each_cpu(j, policy->cpus) {
882 struct device *cpu_dev;
884 if (j == policy->cpu)
887 pr_debug("Adding link for CPU: %u\n", j);
888 cpu_dev = get_cpu_device(j);
889 ret = sysfs_create_link(&cpu_dev->kobj, &policy->kobj,
897 static int cpufreq_add_dev_interface(struct cpufreq_policy *policy,
900 struct freq_attr **drv_attr;
903 /* set up files for this cpu device */
904 drv_attr = cpufreq_driver->attr;
905 while ((drv_attr) && (*drv_attr)) {
906 ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
911 if (cpufreq_driver->get) {
912 ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
917 ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
921 if (cpufreq_driver->bios_limit) {
922 ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
927 return cpufreq_add_dev_symlink(policy);
930 static void cpufreq_init_policy(struct cpufreq_policy *policy)
932 struct cpufreq_governor *gov = NULL;
933 struct cpufreq_policy new_policy;
936 memcpy(&new_policy, policy, sizeof(*policy));
938 /* Update governor of new_policy to the governor used before hotplug */
939 gov = __find_governor(per_cpu(cpufreq_cpu_governor, policy->cpu));
941 pr_debug("Restoring governor %s for cpu %d\n",
942 policy->governor->name, policy->cpu);
944 gov = CPUFREQ_DEFAULT_GOVERNOR;
946 new_policy.governor = gov;
948 /* Use the default policy if its valid. */
949 if (cpufreq_driver->setpolicy)
950 cpufreq_parse_governor(gov->name, &new_policy.policy, NULL);
952 /* set default policy */
953 ret = cpufreq_set_policy(policy, &new_policy);
955 pr_debug("setting policy failed\n");
956 if (cpufreq_driver->exit)
957 cpufreq_driver->exit(policy);
961 #ifdef CONFIG_HOTPLUG_CPU
962 static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy,
963 unsigned int cpu, struct device *dev)
969 ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
971 pr_err("%s: Failed to stop governor\n", __func__);
976 down_write(&policy->rwsem);
978 write_lock_irqsave(&cpufreq_driver_lock, flags);
980 cpumask_set_cpu(cpu, policy->cpus);
981 per_cpu(cpufreq_cpu_data, cpu) = policy;
982 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
984 up_write(&policy->rwsem);
987 ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
989 ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
992 pr_err("%s: Failed to start governor\n", __func__);
997 return sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq");
1001 static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu)
1003 struct cpufreq_policy *policy;
1004 unsigned long flags;
1006 read_lock_irqsave(&cpufreq_driver_lock, flags);
1008 policy = per_cpu(cpufreq_cpu_data_fallback, cpu);
1010 read_unlock_irqrestore(&cpufreq_driver_lock, flags);
1013 policy->governor = NULL;
1018 static struct cpufreq_policy *cpufreq_policy_alloc(void)
1020 struct cpufreq_policy *policy;
1022 policy = kzalloc(sizeof(*policy), GFP_KERNEL);
1026 if (!alloc_cpumask_var(&policy->cpus, GFP_KERNEL))
1027 goto err_free_policy;
1029 if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL))
1030 goto err_free_cpumask;
1032 INIT_LIST_HEAD(&policy->policy_list);
1033 init_rwsem(&policy->rwsem);
1034 spin_lock_init(&policy->transition_lock);
1035 init_waitqueue_head(&policy->transition_wait);
1040 free_cpumask_var(policy->cpus);
1047 static void cpufreq_policy_put_kobj(struct cpufreq_policy *policy)
1049 struct kobject *kobj;
1050 struct completion *cmp;
1052 blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1053 CPUFREQ_REMOVE_POLICY, policy);
1055 down_read(&policy->rwsem);
1056 kobj = &policy->kobj;
1057 cmp = &policy->kobj_unregister;
1058 up_read(&policy->rwsem);
1062 * We need to make sure that the underlying kobj is
1063 * actually not referenced anymore by anybody before we
1064 * proceed with unloading.
1066 pr_debug("waiting for dropping of refcount\n");
1067 wait_for_completion(cmp);
1068 pr_debug("wait complete\n");
1071 static void cpufreq_policy_free(struct cpufreq_policy *policy)
1073 free_cpumask_var(policy->related_cpus);
1074 free_cpumask_var(policy->cpus);
1078 static int update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu,
1079 struct device *cpu_dev)
1083 if (WARN_ON(cpu == policy->cpu))
1086 /* Move kobject to the new policy->cpu */
1087 ret = kobject_move(&policy->kobj, &cpu_dev->kobj);
1089 pr_err("%s: Failed to move kobj: %d\n", __func__, ret);
1093 down_write(&policy->rwsem);
1095 policy->last_cpu = policy->cpu;
1098 up_write(&policy->rwsem);
1100 blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1101 CPUFREQ_UPDATE_POLICY_CPU, policy);
1106 static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
1108 unsigned int j, cpu = dev->id;
1110 struct cpufreq_policy *policy;
1111 unsigned long flags;
1112 bool recover_policy = cpufreq_suspended;
1113 #ifdef CONFIG_HOTPLUG_CPU
1114 struct cpufreq_policy *tpolicy;
1117 if (cpu_is_offline(cpu))
1120 pr_debug("adding CPU %u\n", cpu);
1123 /* check whether a different CPU already registered this
1124 * CPU because it is in the same boat. */
1125 policy = cpufreq_cpu_get(cpu);
1126 if (unlikely(policy)) {
1127 cpufreq_cpu_put(policy);
1132 if (!down_read_trylock(&cpufreq_rwsem))
1135 #ifdef CONFIG_HOTPLUG_CPU
1136 /* Check if this cpu was hot-unplugged earlier and has siblings */
1137 read_lock_irqsave(&cpufreq_driver_lock, flags);
1138 list_for_each_entry(tpolicy, &cpufreq_policy_list, policy_list) {
1139 if (cpumask_test_cpu(cpu, tpolicy->related_cpus)) {
1140 read_unlock_irqrestore(&cpufreq_driver_lock, flags);
1141 ret = cpufreq_add_policy_cpu(tpolicy, cpu, dev);
1142 up_read(&cpufreq_rwsem);
1146 read_unlock_irqrestore(&cpufreq_driver_lock, flags);
1150 * Restore the saved policy when doing light-weight init and fall back
1151 * to the full init if that fails.
1153 policy = recover_policy ? cpufreq_policy_restore(cpu) : NULL;
1155 recover_policy = false;
1156 policy = cpufreq_policy_alloc();
1162 * In the resume path, since we restore a saved policy, the assignment
1163 * to policy->cpu is like an update of the existing policy, rather than
1164 * the creation of a brand new one. So we need to perform this update
1165 * by invoking update_policy_cpu().
1167 if (recover_policy && cpu != policy->cpu)
1168 WARN_ON(update_policy_cpu(policy, cpu, dev));
1172 cpumask_copy(policy->cpus, cpumask_of(cpu));
1174 init_completion(&policy->kobj_unregister);
1175 INIT_WORK(&policy->update, handle_update);
1177 /* call driver. From then on the cpufreq must be able
1178 * to accept all calls to ->verify and ->setpolicy for this CPU
1180 ret = cpufreq_driver->init(policy);
1182 pr_debug("initialization failed\n");
1183 goto err_set_policy_cpu;
1186 down_write(&policy->rwsem);
1188 /* related cpus should atleast have policy->cpus */
1189 cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);
1192 * affected cpus must always be the one, which are online. We aren't
1193 * managing offline cpus here.
1195 cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);
1197 if (!recover_policy) {
1198 policy->user_policy.min = policy->min;
1199 policy->user_policy.max = policy->max;
1201 /* prepare interface data */
1202 ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
1203 &dev->kobj, "cpufreq");
1205 pr_err("%s: failed to init policy->kobj: %d\n",
1207 goto err_init_policy_kobj;
1211 write_lock_irqsave(&cpufreq_driver_lock, flags);
1212 for_each_cpu(j, policy->cpus)
1213 per_cpu(cpufreq_cpu_data, j) = policy;
1214 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
1216 if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
1217 policy->cur = cpufreq_driver->get(policy->cpu);
1219 pr_err("%s: ->get() failed\n", __func__);
1225 * Sometimes boot loaders set CPU frequency to a value outside of
1226 * frequency table present with cpufreq core. In such cases CPU might be
1227 * unstable if it has to run on that frequency for long duration of time
1228 * and so its better to set it to a frequency which is specified in
1229 * freq-table. This also makes cpufreq stats inconsistent as
1230 * cpufreq-stats would fail to register because current frequency of CPU
1231 * isn't found in freq-table.
1233 * Because we don't want this change to effect boot process badly, we go
1234 * for the next freq which is >= policy->cur ('cur' must be set by now,
1235 * otherwise we will end up setting freq to lowest of the table as 'cur'
1236 * is initialized to zero).
1238 * We are passing target-freq as "policy->cur - 1" otherwise
1239 * __cpufreq_driver_target() would simply fail, as policy->cur will be
1240 * equal to target-freq.
1242 if ((cpufreq_driver->flags & CPUFREQ_NEED_INITIAL_FREQ_CHECK)
1244 /* Are we running at unknown frequency ? */
1245 ret = cpufreq_frequency_table_get_index(policy, policy->cur);
1246 if (ret == -EINVAL) {
1247 /* Warn user and fix it */
1248 pr_warn("%s: CPU%d: Running at unlisted freq: %u KHz\n",
1249 __func__, policy->cpu, policy->cur);
1250 ret = __cpufreq_driver_target(policy, policy->cur - 1,
1251 CPUFREQ_RELATION_L);
1254 * Reaching here after boot in a few seconds may not
1255 * mean that system will remain stable at "unknown"
1256 * frequency for longer duration. Hence, a BUG_ON().
1259 pr_warn("%s: CPU%d: Unlisted initial frequency changed to: %u KHz\n",
1260 __func__, policy->cpu, policy->cur);
1264 blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1265 CPUFREQ_START, policy);
1267 if (!recover_policy) {
1268 ret = cpufreq_add_dev_interface(policy, dev);
1270 goto err_out_unregister;
1271 blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1272 CPUFREQ_CREATE_POLICY, policy);
1275 write_lock_irqsave(&cpufreq_driver_lock, flags);
1276 list_add(&policy->policy_list, &cpufreq_policy_list);
1277 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
1279 cpufreq_init_policy(policy);
1281 if (!recover_policy) {
1282 policy->user_policy.policy = policy->policy;
1283 policy->user_policy.governor = policy->governor;
1285 up_write(&policy->rwsem);
1287 kobject_uevent(&policy->kobj, KOBJ_ADD);
1289 up_read(&cpufreq_rwsem);
1291 /* Callback for handling stuff after policy is ready */
1292 if (cpufreq_driver->ready)
1293 cpufreq_driver->ready(policy);
1295 pr_debug("initialization complete\n");
1301 write_lock_irqsave(&cpufreq_driver_lock, flags);
1302 for_each_cpu(j, policy->cpus)
1303 per_cpu(cpufreq_cpu_data, j) = NULL;
1304 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
1306 if (!recover_policy) {
1307 kobject_put(&policy->kobj);
1308 wait_for_completion(&policy->kobj_unregister);
1310 err_init_policy_kobj:
1311 up_write(&policy->rwsem);
1313 if (cpufreq_driver->exit)
1314 cpufreq_driver->exit(policy);
1316 if (recover_policy) {
1317 /* Do not leave stale fallback data behind. */
1318 per_cpu(cpufreq_cpu_data_fallback, cpu) = NULL;
1319 cpufreq_policy_put_kobj(policy);
1321 cpufreq_policy_free(policy);
1324 up_read(&cpufreq_rwsem);
1330 * cpufreq_add_dev - add a CPU device
1332 * Adds the cpufreq interface for a CPU device.
1334 * The Oracle says: try running cpufreq registration/unregistration concurrently
1335 * with with cpu hotplugging and all hell will break loose. Tried to clean this
1336 * mess up, but more thorough testing is needed. - Mathieu
1338 static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
1340 return __cpufreq_add_dev(dev, sif);
1343 static int __cpufreq_remove_dev_prepare(struct device *dev,
1344 struct subsys_interface *sif)
1346 unsigned int cpu = dev->id, cpus;
1348 unsigned long flags;
1349 struct cpufreq_policy *policy;
1351 pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
1353 write_lock_irqsave(&cpufreq_driver_lock, flags);
1355 policy = per_cpu(cpufreq_cpu_data, cpu);
1357 /* Save the policy somewhere when doing a light-weight tear-down */
1358 if (cpufreq_suspended)
1359 per_cpu(cpufreq_cpu_data_fallback, cpu) = policy;
1361 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
1364 pr_debug("%s: No cpu_data found\n", __func__);
1369 ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
1371 pr_err("%s: Failed to stop governor\n", __func__);
1376 if (!cpufreq_driver->setpolicy)
1377 strncpy(per_cpu(cpufreq_cpu_governor, cpu),
1378 policy->governor->name, CPUFREQ_NAME_LEN);
1380 down_read(&policy->rwsem);
1381 cpus = cpumask_weight(policy->cpus);
1382 up_read(&policy->rwsem);
1384 if (cpu != policy->cpu) {
1385 sysfs_remove_link(&dev->kobj, "cpufreq");
1386 } else if (cpus > 1) {
1387 /* Nominate new CPU */
1388 int new_cpu = cpumask_any_but(policy->cpus, cpu);
1389 struct device *cpu_dev = get_cpu_device(new_cpu);
1391 sysfs_remove_link(&cpu_dev->kobj, "cpufreq");
1392 ret = update_policy_cpu(policy, new_cpu, cpu_dev);
1394 if (sysfs_create_link(&cpu_dev->kobj, &policy->kobj,
1396 pr_err("%s: Failed to restore kobj link to cpu:%d\n",
1397 __func__, cpu_dev->id);
1401 if (!cpufreq_suspended)
1402 pr_debug("%s: policy Kobject moved to cpu: %d from: %d\n",
1403 __func__, new_cpu, cpu);
1404 } else if (cpufreq_driver->stop_cpu) {
1405 cpufreq_driver->stop_cpu(policy);
1411 static int __cpufreq_remove_dev_finish(struct device *dev,
1412 struct subsys_interface *sif)
1414 unsigned int cpu = dev->id, cpus;
1416 unsigned long flags;
1417 struct cpufreq_policy *policy;
1419 read_lock_irqsave(&cpufreq_driver_lock, flags);
1420 policy = per_cpu(cpufreq_cpu_data, cpu);
1421 read_unlock_irqrestore(&cpufreq_driver_lock, flags);
1424 pr_debug("%s: No cpu_data found\n", __func__);
1428 down_write(&policy->rwsem);
1429 cpus = cpumask_weight(policy->cpus);
1432 cpumask_clear_cpu(cpu, policy->cpus);
1433 up_write(&policy->rwsem);
1435 /* If cpu is last user of policy, free policy */
1438 ret = __cpufreq_governor(policy,
1439 CPUFREQ_GOV_POLICY_EXIT);
1441 pr_err("%s: Failed to exit governor\n",
1447 if (!cpufreq_suspended)
1448 cpufreq_policy_put_kobj(policy);
1451 * Perform the ->exit() even during light-weight tear-down,
1452 * since this is a core component, and is essential for the
1453 * subsequent light-weight ->init() to succeed.
1455 if (cpufreq_driver->exit)
1456 cpufreq_driver->exit(policy);
1458 /* Remove policy from list of active policies */
1459 write_lock_irqsave(&cpufreq_driver_lock, flags);
1460 list_del(&policy->policy_list);
1461 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
1463 if (!cpufreq_suspended)
1464 cpufreq_policy_free(policy);
1465 } else if (has_target()) {
1466 ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
1468 ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
1471 pr_err("%s: Failed to start governor\n", __func__);
1476 per_cpu(cpufreq_cpu_data, cpu) = NULL;
1481 * cpufreq_remove_dev - remove a CPU device
1483 * Removes the cpufreq interface for a CPU device.
1485 static int cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
1487 unsigned int cpu = dev->id;
1490 if (cpu_is_offline(cpu))
1493 ret = __cpufreq_remove_dev_prepare(dev, sif);
1496 ret = __cpufreq_remove_dev_finish(dev, sif);
1501 static void handle_update(struct work_struct *work)
1503 struct cpufreq_policy *policy =
1504 container_of(work, struct cpufreq_policy, update);
1505 unsigned int cpu = policy->cpu;
1506 pr_debug("handle_update for cpu %u called\n", cpu);
1507 cpufreq_update_policy(cpu);
1511 * cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're
1514 * @old_freq: CPU frequency the kernel thinks the CPU runs at
1515 * @new_freq: CPU frequency the CPU actually runs at
1517 * We adjust to current frequency first, and need to clean up later.
1518 * So either call to cpufreq_update_policy() or schedule handle_update()).
1520 static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq,
1521 unsigned int new_freq)
1523 struct cpufreq_policy *policy;
1524 struct cpufreq_freqs freqs;
1525 unsigned long flags;
1527 pr_debug("Warning: CPU frequency out of sync: cpufreq and timing core thinks of %u, is %u kHz\n",
1528 old_freq, new_freq);
1530 freqs.old = old_freq;
1531 freqs.new = new_freq;
1533 read_lock_irqsave(&cpufreq_driver_lock, flags);
1534 policy = per_cpu(cpufreq_cpu_data, cpu);
1535 read_unlock_irqrestore(&cpufreq_driver_lock, flags);
1537 cpufreq_freq_transition_begin(policy, &freqs);
1538 cpufreq_freq_transition_end(policy, &freqs, 0);
1542 * cpufreq_quick_get - get the CPU frequency (in kHz) from policy->cur
1545 * This is the last known freq, without actually getting it from the driver.
1546 * Return value will be same as what is shown in scaling_cur_freq in sysfs.
1548 unsigned int cpufreq_quick_get(unsigned int cpu)
1550 struct cpufreq_policy *policy;
1551 unsigned int ret_freq = 0;
1553 if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get)
1554 return cpufreq_driver->get(cpu);
1556 policy = cpufreq_cpu_get(cpu);
1558 ret_freq = policy->cur;
1559 cpufreq_cpu_put(policy);
1564 EXPORT_SYMBOL(cpufreq_quick_get);
1567 * cpufreq_quick_get_max - get the max reported CPU frequency for this CPU
1570 * Just return the max possible frequency for a given CPU.
1572 unsigned int cpufreq_quick_get_max(unsigned int cpu)
1574 struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
1575 unsigned int ret_freq = 0;
1578 ret_freq = policy->max;
1579 cpufreq_cpu_put(policy);
1584 EXPORT_SYMBOL(cpufreq_quick_get_max);
1586 static unsigned int __cpufreq_get(unsigned int cpu)
1588 struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
1589 unsigned int ret_freq = 0;
1591 if (!cpufreq_driver->get)
1594 ret_freq = cpufreq_driver->get(cpu);
1596 if (ret_freq && policy->cur &&
1597 !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
1598 /* verify no discrepancy between actual and
1599 saved value exists */
1600 if (unlikely(ret_freq != policy->cur)) {
1601 cpufreq_out_of_sync(cpu, policy->cur, ret_freq);
1602 schedule_work(&policy->update);
1610 * cpufreq_get - get the current CPU frequency (in kHz)
1613 * Get the CPU current (static) CPU frequency
1615 unsigned int cpufreq_get(unsigned int cpu)
1617 struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
1618 unsigned int ret_freq = 0;
1621 down_read(&policy->rwsem);
1622 ret_freq = __cpufreq_get(cpu);
1623 up_read(&policy->rwsem);
1625 cpufreq_cpu_put(policy);
1630 EXPORT_SYMBOL(cpufreq_get);
1632 static struct subsys_interface cpufreq_interface = {
1634 .subsys = &cpu_subsys,
1635 .add_dev = cpufreq_add_dev,
1636 .remove_dev = cpufreq_remove_dev,
1640 * In case platform wants some specific frequency to be configured
1643 int cpufreq_generic_suspend(struct cpufreq_policy *policy)
1647 if (!policy->suspend_freq) {
1648 pr_err("%s: suspend_freq can't be zero\n", __func__);
1652 pr_debug("%s: Setting suspend-freq: %u\n", __func__,
1653 policy->suspend_freq);
1655 ret = __cpufreq_driver_target(policy, policy->suspend_freq,
1656 CPUFREQ_RELATION_H);
1658 pr_err("%s: unable to set suspend-freq: %u. err: %d\n",
1659 __func__, policy->suspend_freq, ret);
1663 EXPORT_SYMBOL(cpufreq_generic_suspend);
1666 * cpufreq_suspend() - Suspend CPUFreq governors
1668 * Called during system wide Suspend/Hibernate cycles for suspending governors
1669 * as some platforms can't change frequency after this point in suspend cycle.
1670 * Because some of the devices (like: i2c, regulators, etc) they use for
1671 * changing frequency are suspended quickly after this point.
1673 void cpufreq_suspend(void)
1675 struct cpufreq_policy *policy;
1677 if (!cpufreq_driver)
1683 pr_debug("%s: Suspending Governors\n", __func__);
1685 list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
1686 if (__cpufreq_governor(policy, CPUFREQ_GOV_STOP))
1687 pr_err("%s: Failed to stop governor for policy: %p\n",
1689 else if (cpufreq_driver->suspend
1690 && cpufreq_driver->suspend(policy))
1691 pr_err("%s: Failed to suspend driver: %p\n", __func__,
1696 cpufreq_suspended = true;
1700 * cpufreq_resume() - Resume CPUFreq governors
1702 * Called during system wide Suspend/Hibernate cycle for resuming governors that
1703 * are suspended with cpufreq_suspend().
1705 void cpufreq_resume(void)
1707 struct cpufreq_policy *policy;
1709 if (!cpufreq_driver)
1712 cpufreq_suspended = false;
1717 pr_debug("%s: Resuming Governors\n", __func__);
1719 list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
1720 if (cpufreq_driver->resume && cpufreq_driver->resume(policy))
1721 pr_err("%s: Failed to resume driver: %p\n", __func__,
1723 else if (__cpufreq_governor(policy, CPUFREQ_GOV_START)
1724 || __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS))
1725 pr_err("%s: Failed to start governor for policy: %p\n",
1729 * schedule call cpufreq_update_policy() for boot CPU, i.e. last
1730 * policy in list. It will verify that the current freq is in
1731 * sync with what we believe it to be.
1733 if (list_is_last(&policy->policy_list, &cpufreq_policy_list))
1734 schedule_work(&policy->update);
1739 * cpufreq_get_current_driver - return current driver's name
1741 * Return the name string of the currently loaded cpufreq driver
1744 const char *cpufreq_get_current_driver(void)
1747 return cpufreq_driver->name;
1751 EXPORT_SYMBOL_GPL(cpufreq_get_current_driver);
1754 * cpufreq_get_driver_data - return current driver data
1756 * Return the private data of the currently loaded cpufreq
1757 * driver, or NULL if no cpufreq driver is loaded.
1759 void *cpufreq_get_driver_data(void)
1762 return cpufreq_driver->driver_data;
1766 EXPORT_SYMBOL_GPL(cpufreq_get_driver_data);
1768 /*********************************************************************
1769 * NOTIFIER LISTS INTERFACE *
1770 *********************************************************************/
1773 * cpufreq_register_notifier - register a driver with cpufreq
1774 * @nb: notifier function to register
1775 * @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
1777 * Add a driver to one of two lists: either a list of drivers that
1778 * are notified about clock rate changes (once before and once after
1779 * the transition), or a list of drivers that are notified about
1780 * changes in cpufreq policy.
1782 * This function may sleep, and has the same return conditions as
1783 * blocking_notifier_chain_register.
1785 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
1789 if (cpufreq_disabled())
1792 WARN_ON(!init_cpufreq_transition_notifier_list_called);
1795 case CPUFREQ_TRANSITION_NOTIFIER:
1796 ret = srcu_notifier_chain_register(
1797 &cpufreq_transition_notifier_list, nb);
1799 case CPUFREQ_POLICY_NOTIFIER:
1800 ret = blocking_notifier_chain_register(
1801 &cpufreq_policy_notifier_list, nb);
1809 EXPORT_SYMBOL(cpufreq_register_notifier);
1812 * cpufreq_unregister_notifier - unregister a driver with cpufreq
1813 * @nb: notifier block to be unregistered
1814 * @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
1816 * Remove a driver from the CPU frequency notifier list.
1818 * This function may sleep, and has the same return conditions as
1819 * blocking_notifier_chain_unregister.
1821 int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
1825 if (cpufreq_disabled())
1829 case CPUFREQ_TRANSITION_NOTIFIER:
1830 ret = srcu_notifier_chain_unregister(
1831 &cpufreq_transition_notifier_list, nb);
1833 case CPUFREQ_POLICY_NOTIFIER:
1834 ret = blocking_notifier_chain_unregister(
1835 &cpufreq_policy_notifier_list, nb);
1843 EXPORT_SYMBOL(cpufreq_unregister_notifier);
1846 /*********************************************************************
1848 *********************************************************************/
1850 /* Must set freqs->new to intermediate frequency */
1851 static int __target_intermediate(struct cpufreq_policy *policy,
1852 struct cpufreq_freqs *freqs, int index)
1856 freqs->new = cpufreq_driver->get_intermediate(policy, index);
1858 /* We don't need to switch to intermediate freq */
1862 pr_debug("%s: cpu: %d, switching to intermediate freq: oldfreq: %u, intermediate freq: %u\n",
1863 __func__, policy->cpu, freqs->old, freqs->new);
1865 cpufreq_freq_transition_begin(policy, freqs);
1866 ret = cpufreq_driver->target_intermediate(policy, index);
1867 cpufreq_freq_transition_end(policy, freqs, ret);
1870 pr_err("%s: Failed to change to intermediate frequency: %d\n",
1876 static int __target_index(struct cpufreq_policy *policy,
1877 struct cpufreq_frequency_table *freq_table, int index)
1879 struct cpufreq_freqs freqs = {.old = policy->cur, .flags = 0};
1880 unsigned int intermediate_freq = 0;
1881 int retval = -EINVAL;
1884 notify = !(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION);
1886 /* Handle switching to intermediate frequency */
1887 if (cpufreq_driver->get_intermediate) {
1888 retval = __target_intermediate(policy, &freqs, index);
1892 intermediate_freq = freqs.new;
1893 /* Set old freq to intermediate */
1894 if (intermediate_freq)
1895 freqs.old = freqs.new;
1898 freqs.new = freq_table[index].frequency;
1899 pr_debug("%s: cpu: %d, oldfreq: %u, new freq: %u\n",
1900 __func__, policy->cpu, freqs.old, freqs.new);
1902 cpufreq_freq_transition_begin(policy, &freqs);
1905 retval = cpufreq_driver->target_index(policy, index);
1907 pr_err("%s: Failed to change cpu frequency: %d\n", __func__,
1911 cpufreq_freq_transition_end(policy, &freqs, retval);
1914 * Failed after setting to intermediate freq? Driver should have
1915 * reverted back to initial frequency and so should we. Check
1916 * here for intermediate_freq instead of get_intermediate, in
1917 * case we have't switched to intermediate freq at all.
1919 if (unlikely(retval && intermediate_freq)) {
1920 freqs.old = intermediate_freq;
1921 freqs.new = policy->restore_freq;
1922 cpufreq_freq_transition_begin(policy, &freqs);
1923 cpufreq_freq_transition_end(policy, &freqs, 0);
1930 int __cpufreq_driver_target(struct cpufreq_policy *policy,
1931 unsigned int target_freq,
1932 unsigned int relation)
1934 unsigned int old_target_freq = target_freq;
1935 int retval = -EINVAL;
1937 if (cpufreq_disabled())
1940 /* Make sure that target_freq is within supported range */
1941 if (target_freq > policy->max)
1942 target_freq = policy->max;
1943 if (target_freq < policy->min)
1944 target_freq = policy->min;
1946 pr_debug("target for CPU %u: %u kHz, relation %u, requested %u kHz\n",
1947 policy->cpu, target_freq, relation, old_target_freq);
1950 * This might look like a redundant call as we are checking it again
1951 * after finding index. But it is left intentionally for cases where
1952 * exactly same freq is called again and so we can save on few function
1955 if (target_freq == policy->cur)
1958 /* Save last value to restore later on errors */
1959 policy->restore_freq = policy->cur;
1961 if (cpufreq_driver->target)
1962 retval = cpufreq_driver->target(policy, target_freq, relation);
1963 else if (cpufreq_driver->target_index) {
1964 struct cpufreq_frequency_table *freq_table;
1967 freq_table = cpufreq_frequency_get_table(policy->cpu);
1968 if (unlikely(!freq_table)) {
1969 pr_err("%s: Unable to find freq_table\n", __func__);
1973 retval = cpufreq_frequency_table_target(policy, freq_table,
1974 target_freq, relation, &index);
1975 if (unlikely(retval)) {
1976 pr_err("%s: Unable to find matching freq\n", __func__);
1980 if (freq_table[index].frequency == policy->cur) {
1985 retval = __target_index(policy, freq_table, index);
1991 EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
1993 int cpufreq_driver_target(struct cpufreq_policy *policy,
1994 unsigned int target_freq,
1995 unsigned int relation)
1999 down_write(&policy->rwsem);
2001 ret = __cpufreq_driver_target(policy, target_freq, relation);
2003 up_write(&policy->rwsem);
2007 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
2010 * when "event" is CPUFREQ_GOV_LIMITS
2013 static int __cpufreq_governor(struct cpufreq_policy *policy,
2018 /* Only must be defined when default governor is known to have latency
2019 restrictions, like e.g. conservative or ondemand.
2020 That this is the case is already ensured in Kconfig
2022 #ifdef CONFIG_CPU_FREQ_GOV_PERFORMANCE
2023 struct cpufreq_governor *gov = &cpufreq_gov_performance;
2025 struct cpufreq_governor *gov = NULL;
2028 /* Don't start any governor operations if we are entering suspend */
2029 if (cpufreq_suspended)
2032 * Governor might not be initiated here if ACPI _PPC changed
2033 * notification happened, so check it.
2035 if (!policy->governor)
2038 if (policy->governor->max_transition_latency &&
2039 policy->cpuinfo.transition_latency >
2040 policy->governor->max_transition_latency) {
2044 pr_warn("%s governor failed, too long transition latency of HW, fallback to %s governor\n",
2045 policy->governor->name, gov->name);
2046 policy->governor = gov;
2050 if (event == CPUFREQ_GOV_POLICY_INIT)
2051 if (!try_module_get(policy->governor->owner))
2054 pr_debug("__cpufreq_governor for CPU %u, event %u\n",
2055 policy->cpu, event);
2057 mutex_lock(&cpufreq_governor_lock);
2058 if ((policy->governor_enabled && event == CPUFREQ_GOV_START)
2059 || (!policy->governor_enabled
2060 && (event == CPUFREQ_GOV_LIMITS || event == CPUFREQ_GOV_STOP))) {
2061 mutex_unlock(&cpufreq_governor_lock);
2065 if (event == CPUFREQ_GOV_STOP)
2066 policy->governor_enabled = false;
2067 else if (event == CPUFREQ_GOV_START)
2068 policy->governor_enabled = true;
2070 mutex_unlock(&cpufreq_governor_lock);
2072 ret = policy->governor->governor(policy, event);
2075 if (event == CPUFREQ_GOV_POLICY_INIT)
2076 policy->governor->initialized++;
2077 else if (event == CPUFREQ_GOV_POLICY_EXIT)
2078 policy->governor->initialized--;
2080 /* Restore original values */
2081 mutex_lock(&cpufreq_governor_lock);
2082 if (event == CPUFREQ_GOV_STOP)
2083 policy->governor_enabled = true;
2084 else if (event == CPUFREQ_GOV_START)
2085 policy->governor_enabled = false;
2086 mutex_unlock(&cpufreq_governor_lock);
2089 if (((event == CPUFREQ_GOV_POLICY_INIT) && ret) ||
2090 ((event == CPUFREQ_GOV_POLICY_EXIT) && !ret))
2091 module_put(policy->governor->owner);
2096 int cpufreq_register_governor(struct cpufreq_governor *governor)
2103 if (cpufreq_disabled())
2106 mutex_lock(&cpufreq_governor_mutex);
2108 governor->initialized = 0;
2110 if (__find_governor(governor->name) == NULL) {
2112 list_add(&governor->governor_list, &cpufreq_governor_list);
2115 mutex_unlock(&cpufreq_governor_mutex);
2118 EXPORT_SYMBOL_GPL(cpufreq_register_governor);
2120 void cpufreq_unregister_governor(struct cpufreq_governor *governor)
2127 if (cpufreq_disabled())
2130 for_each_present_cpu(cpu) {
2131 if (cpu_online(cpu))
2133 if (!strcmp(per_cpu(cpufreq_cpu_governor, cpu), governor->name))
2134 strcpy(per_cpu(cpufreq_cpu_governor, cpu), "\0");
2137 mutex_lock(&cpufreq_governor_mutex);
2138 list_del(&governor->governor_list);
2139 mutex_unlock(&cpufreq_governor_mutex);
2142 EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
2145 /*********************************************************************
2146 * POLICY INTERFACE *
2147 *********************************************************************/
2150 * cpufreq_get_policy - get the current cpufreq_policy
2151 * @policy: struct cpufreq_policy into which the current cpufreq_policy
2154 * Reads the current cpufreq policy.
2156 int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
2158 struct cpufreq_policy *cpu_policy;
2162 cpu_policy = cpufreq_cpu_get(cpu);
2166 memcpy(policy, cpu_policy, sizeof(*policy));
2168 cpufreq_cpu_put(cpu_policy);
2171 EXPORT_SYMBOL(cpufreq_get_policy);
2174 * policy : current policy.
2175 * new_policy: policy to be set.
2177 static int cpufreq_set_policy(struct cpufreq_policy *policy,
2178 struct cpufreq_policy *new_policy)
2180 struct cpufreq_governor *old_gov;
2183 pr_debug("setting new policy for CPU %u: %u - %u kHz\n",
2184 new_policy->cpu, new_policy->min, new_policy->max);
2186 memcpy(&new_policy->cpuinfo, &policy->cpuinfo, sizeof(policy->cpuinfo));
2188 if (new_policy->min > policy->max || new_policy->max < policy->min)
2191 /* verify the cpu speed can be set within this limit */
2192 ret = cpufreq_driver->verify(new_policy);
2196 /* adjust if necessary - all reasons */
2197 blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
2198 CPUFREQ_ADJUST, new_policy);
2200 /* adjust if necessary - hardware incompatibility*/
2201 blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
2202 CPUFREQ_INCOMPATIBLE, new_policy);
2205 * verify the cpu speed can be set within this limit, which might be
2206 * different to the first one
2208 ret = cpufreq_driver->verify(new_policy);
2212 /* notification of the new policy */
2213 blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
2214 CPUFREQ_NOTIFY, new_policy);
2216 policy->min = new_policy->min;
2217 policy->max = new_policy->max;
2219 pr_debug("new min and max freqs are %u - %u kHz\n",
2220 policy->min, policy->max);
2222 if (cpufreq_driver->setpolicy) {
2223 policy->policy = new_policy->policy;
2224 pr_debug("setting range\n");
2225 return cpufreq_driver->setpolicy(new_policy);
2228 if (new_policy->governor == policy->governor)
2231 pr_debug("governor switch\n");
2233 /* save old, working values */
2234 old_gov = policy->governor;
2235 /* end old governor */
2237 __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
2238 up_write(&policy->rwsem);
2239 __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
2240 down_write(&policy->rwsem);
2243 /* start new governor */
2244 policy->governor = new_policy->governor;
2245 if (!__cpufreq_governor(policy, CPUFREQ_GOV_POLICY_INIT)) {
2246 if (!__cpufreq_governor(policy, CPUFREQ_GOV_START))
2249 up_write(&policy->rwsem);
2250 __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
2251 down_write(&policy->rwsem);
2254 /* new governor failed, so re-start old one */
2255 pr_debug("starting governor %s failed\n", policy->governor->name);
2257 policy->governor = old_gov;
2258 __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_INIT);
2259 __cpufreq_governor(policy, CPUFREQ_GOV_START);
2265 pr_debug("governor: change or update limits\n");
2266 return __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
2270 * cpufreq_update_policy - re-evaluate an existing cpufreq policy
2271 * @cpu: CPU which shall be re-evaluated
2273 * Useful for policy notifiers which have different necessities
2274 * at different times.
2276 int cpufreq_update_policy(unsigned int cpu)
2278 struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
2279 struct cpufreq_policy new_policy;
2285 down_write(&policy->rwsem);
2287 pr_debug("updating policy for CPU %u\n", cpu);
2288 memcpy(&new_policy, policy, sizeof(*policy));
2289 new_policy.min = policy->user_policy.min;
2290 new_policy.max = policy->user_policy.max;
2291 new_policy.policy = policy->user_policy.policy;
2292 new_policy.governor = policy->user_policy.governor;
2295 * BIOS might change freq behind our back
2296 * -> ask driver for current freq and notify governors about a change
2298 if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
2299 new_policy.cur = cpufreq_driver->get(cpu);
2300 if (WARN_ON(!new_policy.cur)) {
2306 pr_debug("Driver did not initialize current freq\n");
2307 policy->cur = new_policy.cur;
2309 if (policy->cur != new_policy.cur && has_target())
2310 cpufreq_out_of_sync(cpu, policy->cur,
2315 ret = cpufreq_set_policy(policy, &new_policy);
2318 up_write(&policy->rwsem);
2320 cpufreq_cpu_put(policy);
2323 EXPORT_SYMBOL(cpufreq_update_policy);
2325 static int cpufreq_cpu_callback(struct notifier_block *nfb,
2326 unsigned long action, void *hcpu)
2328 unsigned int cpu = (unsigned long)hcpu;
2331 dev = get_cpu_device(cpu);
2333 switch (action & ~CPU_TASKS_FROZEN) {
2335 __cpufreq_add_dev(dev, NULL);
2338 case CPU_DOWN_PREPARE:
2339 __cpufreq_remove_dev_prepare(dev, NULL);
2343 __cpufreq_remove_dev_finish(dev, NULL);
2346 case CPU_DOWN_FAILED:
2347 __cpufreq_add_dev(dev, NULL);
2354 static struct notifier_block __refdata cpufreq_cpu_notifier = {
2355 .notifier_call = cpufreq_cpu_callback,
2358 /*********************************************************************
2360 *********************************************************************/
2361 static int cpufreq_boost_set_sw(int state)
2363 struct cpufreq_frequency_table *freq_table;
2364 struct cpufreq_policy *policy;
2367 list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
2368 freq_table = cpufreq_frequency_get_table(policy->cpu);
2370 ret = cpufreq_frequency_table_cpuinfo(policy,
2373 pr_err("%s: Policy frequency update failed\n",
2377 policy->user_policy.max = policy->max;
2378 __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
2385 int cpufreq_boost_trigger_state(int state)
2387 unsigned long flags;
2390 if (cpufreq_driver->boost_enabled == state)
2393 write_lock_irqsave(&cpufreq_driver_lock, flags);
2394 cpufreq_driver->boost_enabled = state;
2395 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2397 ret = cpufreq_driver->set_boost(state);
2399 write_lock_irqsave(&cpufreq_driver_lock, flags);
2400 cpufreq_driver->boost_enabled = !state;
2401 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2403 pr_err("%s: Cannot %s BOOST\n",
2404 __func__, state ? "enable" : "disable");
2410 int cpufreq_boost_supported(void)
2412 if (likely(cpufreq_driver))
2413 return cpufreq_driver->boost_supported;
2417 EXPORT_SYMBOL_GPL(cpufreq_boost_supported);
2419 int cpufreq_boost_enabled(void)
2421 return cpufreq_driver->boost_enabled;
2423 EXPORT_SYMBOL_GPL(cpufreq_boost_enabled);
2425 /*********************************************************************
2426 * REGISTER / UNREGISTER CPUFREQ DRIVER *
2427 *********************************************************************/
2430 * cpufreq_register_driver - register a CPU Frequency driver
2431 * @driver_data: A struct cpufreq_driver containing the values#
2432 * submitted by the CPU Frequency driver.
2434 * Registers a CPU Frequency driver to this core code. This code
2435 * returns zero on success, -EBUSY when another driver got here first
2436 * (and isn't unregistered in the meantime).
2439 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
2441 unsigned long flags;
2444 if (cpufreq_disabled())
2447 if (!driver_data || !driver_data->verify || !driver_data->init ||
2448 !(driver_data->setpolicy || driver_data->target_index ||
2449 driver_data->target) ||
2450 (driver_data->setpolicy && (driver_data->target_index ||
2451 driver_data->target)) ||
2452 (!!driver_data->get_intermediate != !!driver_data->target_intermediate))
2455 pr_debug("trying to register driver %s\n", driver_data->name);
2457 if (driver_data->setpolicy)
2458 driver_data->flags |= CPUFREQ_CONST_LOOPS;
2460 write_lock_irqsave(&cpufreq_driver_lock, flags);
2461 if (cpufreq_driver) {
2462 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2465 cpufreq_driver = driver_data;
2466 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2468 if (cpufreq_boost_supported()) {
2470 * Check if driver provides function to enable boost -
2471 * if not, use cpufreq_boost_set_sw as default
2473 if (!cpufreq_driver->set_boost)
2474 cpufreq_driver->set_boost = cpufreq_boost_set_sw;
2476 ret = cpufreq_sysfs_create_file(&boost.attr);
2478 pr_err("%s: cannot register global BOOST sysfs file\n",
2480 goto err_null_driver;
2484 ret = subsys_interface_register(&cpufreq_interface);
2486 goto err_boost_unreg;
2488 if (!(cpufreq_driver->flags & CPUFREQ_STICKY)) {
2492 /* check for at least one working CPU */
2493 for (i = 0; i < nr_cpu_ids; i++)
2494 if (cpu_possible(i) && per_cpu(cpufreq_cpu_data, i)) {
2499 /* if all ->init() calls failed, unregister */
2501 pr_debug("no CPU initialized for driver %s\n",
2507 register_hotcpu_notifier(&cpufreq_cpu_notifier);
2508 pr_debug("driver %s up and running\n", driver_data->name);
2512 subsys_interface_unregister(&cpufreq_interface);
2514 if (cpufreq_boost_supported())
2515 cpufreq_sysfs_remove_file(&boost.attr);
2517 write_lock_irqsave(&cpufreq_driver_lock, flags);
2518 cpufreq_driver = NULL;
2519 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2522 EXPORT_SYMBOL_GPL(cpufreq_register_driver);
2525 * cpufreq_unregister_driver - unregister the current CPUFreq driver
2527 * Unregister the current CPUFreq driver. Only call this if you have
2528 * the right to do so, i.e. if you have succeeded in initialising before!
2529 * Returns zero if successful, and -EINVAL if the cpufreq_driver is
2530 * currently not initialised.
2532 int cpufreq_unregister_driver(struct cpufreq_driver *driver)
2534 unsigned long flags;
2536 if (!cpufreq_driver || (driver != cpufreq_driver))
2539 pr_debug("unregistering driver %s\n", driver->name);
2541 subsys_interface_unregister(&cpufreq_interface);
2542 if (cpufreq_boost_supported())
2543 cpufreq_sysfs_remove_file(&boost.attr);
2545 unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
2547 down_write(&cpufreq_rwsem);
2548 write_lock_irqsave(&cpufreq_driver_lock, flags);
2550 cpufreq_driver = NULL;
2552 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2553 up_write(&cpufreq_rwsem);
2557 EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
2559 static int __init cpufreq_core_init(void)
2561 if (cpufreq_disabled())
2564 cpufreq_global_kobject = kobject_create();
2565 BUG_ON(!cpufreq_global_kobject);
2569 core_initcall(cpufreq_core_init);