drivers/cpufreq/cpufreq.c

   1 /*
   2  *  linux/drivers/cpufreq/cpufreq.c
   3  *
   4  *  Copyright (C) 2001 Russell King
   5  *            (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
   6  *            (C) 2013 Viresh Kumar <viresh.kumar@linaro.org>
   7  *
   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
  12  *
  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.
  16  */
  17
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/cpu.h>
  21 #include <linux/cpufreq.h>
  22 #include <linux/cpu_cooling.h>
  23 #include <linux/delay.h>
  24 #include <linux/device.h>
  25 #include <linux/init.h>
  26 #include <linux/kernel_stat.h>
  27 #include <linux/module.h>
  28 #include <linux/mutex.h>
  29 #include <linux/slab.h>
  30 #include <linux/suspend.h>
  31 #include <linux/syscore_ops.h>
  32 #include <linux/tick.h>
  33 #include <trace/events/power.h>
  34
  35 static LIST_HEAD(cpufreq_policy_list);
  36
  37 /* Macros to iterate over CPU policies */
  38 #define for_each_suitable_policy(__policy, __active)                     \
  39         list_for_each_entry(__policy, &cpufreq_policy_list, policy_list) \
  40                 if ((__active) == !policy_is_inactive(__policy))
  41
  42 #define for_each_active_policy(__policy)                \
  43         for_each_suitable_policy(__policy, true)
  44 #define for_each_inactive_policy(__policy)              \
  45         for_each_suitable_policy(__policy, false)
  46
  47 #define for_each_policy(__policy)                       \
  48         list_for_each_entry(__policy, &cpufreq_policy_list, policy_list)
  49
  50 /* Iterate over governors */
  51 static LIST_HEAD(cpufreq_governor_list);
  52 #define for_each_governor(__governor)                           \
  53         list_for_each_entry(__governor, &cpufreq_governor_list, governor_list)
  54
  55 /**
  56  * The "cpufreq driver" - the arch- or hardware-dependent low
  57  * level driver of CPUFreq support, and its spinlock. This lock
  58  * also protects the cpufreq_cpu_data array.
  59  */
  60 static struct cpufreq_driver *cpufreq_driver;
  61 static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
  62 static DEFINE_RWLOCK(cpufreq_driver_lock);
  63
  64 /* Flag to suspend/resume CPUFreq governors */
  65 static bool cpufreq_suspended;
  66
  67 static inline bool has_target(void)
  68 {
  69         return cpufreq_driver->target_index || cpufreq_driver->target;
  70 }
  71
  72 /* internal prototypes */
  73 static unsigned int __cpufreq_get(struct cpufreq_policy *policy);
  74 static int cpufreq_init_governor(struct cpufreq_policy *policy);
  75 static void cpufreq_exit_governor(struct cpufreq_policy *policy);
  76 static int cpufreq_start_governor(struct cpufreq_policy *policy);
  77 static void cpufreq_stop_governor(struct cpufreq_policy *policy);
  78 static void cpufreq_governor_limits(struct cpufreq_policy *policy);
  79
  80 /**
  81  * Two notifier lists: the "policy" list is involved in the
  82  * validation process for a new CPU frequency policy; the
  83  * "transition" list for kernel code that needs to handle
  84  * changes to devices when the CPU clock speed changes.
  85  * The mutex locks both lists.
  86  */
  87 static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
  88 SRCU_NOTIFIER_HEAD_STATIC(cpufreq_transition_notifier_list);
  89
  90 static int off __read_mostly;
  91 static int cpufreq_disabled(void)
  92 {
  93         return off;
  94 }
  95 void disable_cpufreq(void)
  96 {
  97         off = 1;
  98 }
  99 static DEFINE_MUTEX(cpufreq_governor_mutex);
 100
 101 bool have_governor_per_policy(void)
 102 {
 103         return !!(cpufreq_driver->flags & CPUFREQ_HAVE_GOVERNOR_PER_POLICY);
 104 }
 105 EXPORT_SYMBOL_GPL(have_governor_per_policy);
 106
 107 struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy)
 108 {
 109         if (have_governor_per_policy())
 110                 return &policy->kobj;
 111         else
 112                 return cpufreq_global_kobject;
 113 }
 114 EXPORT_SYMBOL_GPL(get_governor_parent_kobj);
 115
 116 static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
 117 {
 118         u64 idle_time;
 119         u64 cur_wall_time;
 120         u64 busy_time;
 121
 122         cur_wall_time = jiffies64_to_nsecs(get_jiffies_64());
 123
 124         busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
 125         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
 126         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
 127         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
 128         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
 129         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
 130
 131         idle_time = cur_wall_time - busy_time;
 132         if (wall)
 133                 *wall = div_u64(cur_wall_time, NSEC_PER_USEC);
 134
 135         return div_u64(idle_time, NSEC_PER_USEC);
 136 }
 137
 138 u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy)
 139 {
 140         u64 idle_time = get_cpu_idle_time_us(cpu, io_busy ? wall : NULL);
 141
 142         if (idle_time == -1ULL)
 143                 return get_cpu_idle_time_jiffy(cpu, wall);
 144         else if (!io_busy)
 145                 idle_time += get_cpu_iowait_time_us(cpu, wall);
 146
 147         return idle_time;
 148 }
 149 EXPORT_SYMBOL_GPL(get_cpu_idle_time);
 150
 151 __weak void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
 152                 unsigned long max_freq)
 153 {
 154 }
 155 EXPORT_SYMBOL_GPL(arch_set_freq_scale);
 156
 157 /*
 158  * This is a generic cpufreq init() routine which can be used by cpufreq
 159  * drivers of SMP systems. It will do following:
 160  * - validate & show freq table passed
 161  * - set policies transition latency
 162  * - policy->cpus with all possible CPUs
 163  */
 164 int cpufreq_generic_init(struct cpufreq_policy *policy,
 165                 struct cpufreq_frequency_table *table,
 166                 unsigned int transition_latency)
 167 {
 168         policy->freq_table = table;
 169         policy->cpuinfo.transition_latency = transition_latency;
 170
 171         /*
 172          * The driver only supports the SMP configuration where all processors
 173          * share the clock and voltage and clock.
 174          */
 175         cpumask_setall(policy->cpus);
 176
 177         return 0;
 178 }
 179 EXPORT_SYMBOL_GPL(cpufreq_generic_init);
 180
 181 struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu)
 182 {
 183         struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
 184
 185         return policy && cpumask_test_cpu(cpu, policy->cpus) ? policy : NULL;
 186 }
 187 EXPORT_SYMBOL_GPL(cpufreq_cpu_get_raw);
 188
 189 unsigned int cpufreq_generic_get(unsigned int cpu)
 190 {
 191         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
 192
 193         if (!policy || IS_ERR(policy->clk)) {
 194                 pr_err("%s: No %s associated to cpu: %d\n",
 195                        __func__, policy ? "clk" : "policy", cpu);
 196                 return 0;
 197         }
 198
 199         return clk_get_rate(policy->clk) / 1000;
 200 }
 201 EXPORT_SYMBOL_GPL(cpufreq_generic_get);
 202
 203 /**
 204  * cpufreq_cpu_get - Return policy for a CPU and mark it as busy.
 205  * @cpu: CPU to find the policy for.
 206  *
 207  * Call cpufreq_cpu_get_raw() to obtain a cpufreq policy for @cpu and increment
 208  * the kobject reference counter of that policy.  Return a valid policy on
 209  * success or NULL on failure.
 210  *
 211  * The policy returned by this function has to be released with the help of
 212  * cpufreq_cpu_put() to balance its kobject reference counter properly.
 213  */
 214 struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
 215 {
 216         struct cpufreq_policy *policy = NULL;
 217         unsigned long flags;
 218
 219         if (WARN_ON(cpu >= nr_cpu_ids))
 220                 return NULL;
 221
 222         /* get the cpufreq driver */
 223         read_lock_irqsave(&cpufreq_driver_lock, flags);
 224
 225         if (cpufreq_driver) {
 226                 /* get the CPU */
 227                 policy = cpufreq_cpu_get_raw(cpu);
 228                 if (policy)
 229                         kobject_get(&policy->kobj);
 230         }
 231
 232         read_unlock_irqrestore(&cpufreq_driver_lock, flags);
 233
 234         return policy;
 235 }
 236 EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
 237
 238 /**
 239  * cpufreq_cpu_put - Decrement kobject usage counter for cpufreq policy.
 240  * @policy: cpufreq policy returned by cpufreq_cpu_get().
 241  */
 242 void cpufreq_cpu_put(struct cpufreq_policy *policy)
 243 {
 244         kobject_put(&policy->kobj);
 245 }
 246 EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
 247
 248 /**
 249  * cpufreq_cpu_release - Unlock a policy and decrement its usage counter.
 250  * @policy: cpufreq policy returned by cpufreq_cpu_acquire().
 251  */
 252 void cpufreq_cpu_release(struct cpufreq_policy *policy)
 253 {
 254         if (WARN_ON(!policy))
 255                 return;
 256
 257         lockdep_assert_held(&policy->rwsem);
 258
 259         up_write(&policy->rwsem);
 260
 261         cpufreq_cpu_put(policy);
 262 }
 263
 264 /**
 265  * cpufreq_cpu_acquire - Find policy for a CPU, mark it as busy and lock it.
 266  * @cpu: CPU to find the policy for.
 267  *
 268  * Call cpufreq_cpu_get() to get a reference on the cpufreq policy for @cpu and
 269  * if the policy returned by it is not NULL, acquire its rwsem for writing.
 270  * Return the policy if it is active or release it and return NULL otherwise.
 271  *
 272  * The policy returned by this function has to be released with the help of
 273  * cpufreq_cpu_release() in order to release its rwsem and balance its usage
 274  * counter properly.
 275  */
 276 struct cpufreq_policy *cpufreq_cpu_acquire(unsigned int cpu)
 277 {
 278         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
 279
 280         if (!policy)
 281                 return NULL;
 282
 283         down_write(&policy->rwsem);
 284
 285         if (policy_is_inactive(policy)) {
 286                 cpufreq_cpu_release(policy);
 287                 return NULL;
 288         }
 289
 290         return policy;
 291 }
 292
 293 /*********************************************************************
 294  *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
 295  *********************************************************************/
 296
 297 /**
 298  * adjust_jiffies - adjust the system "loops_per_jiffy"
 299  *
 300  * This function alters the system "loops_per_jiffy" for the clock
 301  * speed change. Note that loops_per_jiffy cannot be updated on SMP
 302  * systems as each CPU might be scaled differently. So, use the arch
 303  * per-CPU loops_per_jiffy value wherever possible.
 304  */
 305 static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 306 {
 307 #ifndef CONFIG_SMP
 308         static unsigned long l_p_j_ref;
 309         static unsigned int l_p_j_ref_freq;
 310
 311         if (ci->flags & CPUFREQ_CONST_LOOPS)
 312                 return;
 313
 314         if (!l_p_j_ref_freq) {
 315                 l_p_j_ref = loops_per_jiffy;
 316                 l_p_j_ref_freq = ci->old;
 317                 pr_debug("saving %lu as reference value for loops_per_jiffy; freq is %u kHz\n",
 318                          l_p_j_ref, l_p_j_ref_freq);
 319         }
 320         if (val == CPUFREQ_POSTCHANGE && ci->old != ci->new) {
 321                 loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq,
 322                                                                 ci->new);
 323                 pr_debug("scaling loops_per_jiffy to %lu for frequency %u kHz\n",
 324                          loops_per_jiffy, ci->new);
 325         }
 326 #endif
 327 }
 328
 329 /**
 330  * cpufreq_notify_transition - Notify frequency transition and adjust_jiffies.
 331  * @policy: cpufreq policy to enable fast frequency switching for.
 332  * @freqs: contain details of the frequency update.
 333  * @state: set to CPUFREQ_PRECHANGE or CPUFREQ_POSTCHANGE.
 334  *
 335  * This function calls the transition notifiers and the "adjust_jiffies"
 336  * function. It is called twice on all CPU frequency changes that have
 337  * external effects.
 338  */
 339 static void cpufreq_notify_transition(struct cpufreq_policy *policy,
 340                                       struct cpufreq_freqs *freqs,
 341                                       unsigned int state)
 342 {
 343         int cpu;
 344
 345         BUG_ON(irqs_disabled());
 346
 347         if (cpufreq_disabled())
 348                 return;
 349
 350         freqs->policy = policy;
 351         freqs->flags = cpufreq_driver->flags;
 352         pr_debug("notification %u of frequency transition to %u kHz\n",
 353                  state, freqs->new);
 354
 355         switch (state) {
 356         case CPUFREQ_PRECHANGE:
 357                 /*
 358                  * Detect if the driver reported a value as "old frequency"
 359                  * which is not equal to what the cpufreq core thinks is
 360                  * "old frequency".
 361                  */
 362                 if (policy->cur && policy->cur != freqs->old) {
 363                         pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
 364                                  freqs->old, policy->cur);
 365                         freqs->old = policy->cur;
 366                 }
 367
 368                 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
 369                                          CPUFREQ_PRECHANGE, freqs);
 370
 371                 adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
 372                 break;
 373
 374         case CPUFREQ_POSTCHANGE:
 375                 adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
 376                 pr_debug("FREQ: %u - CPUs: %*pbl\n", freqs->new,
 377                          cpumask_pr_args(policy->cpus));
 378
 379                 for_each_cpu(cpu, policy->cpus)
 380                         trace_cpu_frequency(freqs->new, cpu);
 381
 382                 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
 383                                          CPUFREQ_POSTCHANGE, freqs);
 384
 385                 cpufreq_stats_record_transition(policy, freqs->new);
 386                 policy->cur = freqs->new;
 387         }
 388 }
 389
 390 /* Do post notifications when there are chances that transition has failed */
 391 static void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
 392                 struct cpufreq_freqs *freqs, int transition_failed)
 393 {
 394         cpufreq_notify_transition(policy, freqs, CPUFREQ_POSTCHANGE);
 395         if (!transition_failed)
 396                 return;
 397
 398         swap(freqs->old, freqs->new);
 399         cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
 400         cpufreq_notify_transition(policy, freqs, CPUFREQ_POSTCHANGE);
 401 }
 402
 403 void cpufreq_freq_transition_begin(struct cpufreq_policy *policy,
 404                 struct cpufreq_freqs *freqs)
 405 {
 406
 407         /*
 408          * Catch double invocations of _begin() which lead to self-deadlock.
 409          * ASYNC_NOTIFICATION drivers are left out because the cpufreq core
 410          * doesn't invoke _begin() on their behalf, and hence the chances of
 411          * double invocations are very low. Moreover, there are scenarios
 412          * where these checks can emit false-positive warnings in these
 413          * drivers; so we avoid that by skipping them altogether.
 414          */
 415         WARN_ON(!(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION)
 416                                 && current == policy->transition_task);
 417
 418 wait:
 419         wait_event(policy->transition_wait, !policy->transition_ongoing);
 420
 421         spin_lock(&policy->transition_lock);
 422
 423         if (unlikely(policy->transition_ongoing)) {
 424                 spin_unlock(&policy->transition_lock);
 425                 goto wait;
 426         }
 427
 428         policy->transition_ongoing = true;
 429         policy->transition_task = current;
 430
 431         spin_unlock(&policy->transition_lock);
 432
 433         cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
 434 }
 435 EXPORT_SYMBOL_GPL(cpufreq_freq_transition_begin);
 436
 437 void cpufreq_freq_transition_end(struct cpufreq_policy *policy,
 438                 struct cpufreq_freqs *freqs, int transition_failed)
 439 {
 440         if (WARN_ON(!policy->transition_ongoing))
 441                 return;
 442
 443         cpufreq_notify_post_transition(policy, freqs, transition_failed);
 444
 445         policy->transition_ongoing = false;
 446         policy->transition_task = NULL;
 447
 448         wake_up(&policy->transition_wait);
 449 }
 450 EXPORT_SYMBOL_GPL(cpufreq_freq_transition_end);
 451
 452 /*
 453  * Fast frequency switching status count.  Positive means "enabled", negative
 454  * means "disabled" and 0 means "not decided yet".
 455  */
 456 static int cpufreq_fast_switch_count;
 457 static DEFINE_MUTEX(cpufreq_fast_switch_lock);
 458
 459 static void cpufreq_list_transition_notifiers(void)
 460 {
 461         struct notifier_block *nb;
 462
 463         pr_info("Registered transition notifiers:\n");
 464
 465         mutex_lock(&cpufreq_transition_notifier_list.mutex);
 466
 467         for (nb = cpufreq_transition_notifier_list.head; nb; nb = nb->next)
 468                 pr_info("%pS\n", nb->notifier_call);
 469
 470         mutex_unlock(&cpufreq_transition_notifier_list.mutex);
 471 }
 472
 473 /**
 474  * cpufreq_enable_fast_switch - Enable fast frequency switching for policy.
 475  * @policy: cpufreq policy to enable fast frequency switching for.
 476  *
 477  * Try to enable fast frequency switching for @policy.
 478  *
 479  * The attempt will fail if there is at least one transition notifier registered
 480  * at this point, as fast frequency switching is quite fundamentally at odds
 481  * with transition notifiers.  Thus if successful, it will make registration of
 482  * transition notifiers fail going forward.
 483  */
 484 void cpufreq_enable_fast_switch(struct cpufreq_policy *policy)
 485 {
 486         lockdep_assert_held(&policy->rwsem);
 487
 488         if (!policy->fast_switch_possible)
 489                 return;
 490
 491         mutex_lock(&cpufreq_fast_switch_lock);
 492         if (cpufreq_fast_switch_count >= 0) {
 493                 cpufreq_fast_switch_count++;
 494                 policy->fast_switch_enabled = true;
 495         } else {
 496                 pr_warn("CPU%u: Fast frequency switching not enabled\n",
 497                         policy->cpu);
 498                 cpufreq_list_transition_notifiers();
 499         }
 500         mutex_unlock(&cpufreq_fast_switch_lock);
 501 }
 502 EXPORT_SYMBOL_GPL(cpufreq_enable_fast_switch);
 503
 504 /**
 505  * cpufreq_disable_fast_switch - Disable fast frequency switching for policy.
 506  * @policy: cpufreq policy to disable fast frequency switching for.
 507  */
 508 void cpufreq_disable_fast_switch(struct cpufreq_policy *policy)
 509 {
 510         mutex_lock(&cpufreq_fast_switch_lock);
 511         if (policy->fast_switch_enabled) {
 512                 policy->fast_switch_enabled = false;
 513                 if (!WARN_ON(cpufreq_fast_switch_count <= 0))
 514                         cpufreq_fast_switch_count--;
 515         }
 516         mutex_unlock(&cpufreq_fast_switch_lock);
 517 }
 518 EXPORT_SYMBOL_GPL(cpufreq_disable_fast_switch);
 519
 520 /**
 521  * cpufreq_driver_resolve_freq - Map a target frequency to a driver-supported
 522  * one.
 523  * @target_freq: target frequency to resolve.
 524  *
 525  * The target to driver frequency mapping is cached in the policy.
 526  *
 527  * Return: Lowest driver-supported frequency greater than or equal to the
 528  * given target_freq, subject to policy (min/max) and driver limitations.
 529  */
 530 unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy,
 531                                          unsigned int target_freq)
 532 {
 533         target_freq = clamp_val(target_freq, policy->min, policy->max);
 534         policy->cached_target_freq = target_freq;
 535
 536         if (cpufreq_driver->target_index) {
 537                 int idx;
 538
 539                 idx = cpufreq_frequency_table_target(policy, target_freq,
 540                                                      CPUFREQ_RELATION_L);
 541                 policy->cached_resolved_idx = idx;
 542                 return policy->freq_table[idx].frequency;
 543         }
 544
 545         if (cpufreq_driver->resolve_freq)
 546                 return cpufreq_driver->resolve_freq(policy, target_freq);
 547
 548         return target_freq;
 549 }
 550 EXPORT_SYMBOL_GPL(cpufreq_driver_resolve_freq);
 551
 552 unsigned int cpufreq_policy_transition_delay_us(struct cpufreq_policy *policy)
 553 {
 554         unsigned int latency;
 555
 556         if (policy->transition_delay_us)
 557                 return policy->transition_delay_us;
 558
 559         latency = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
 560         if (latency) {
 561                 /*
 562                  * For platforms that can change the frequency very fast (< 10
 563                  * us), the above formula gives a decent transition delay. But
 564                  * for platforms where transition_latency is in milliseconds, it
 565                  * ends up giving unrealistic values.
 566                  *
 567                  * Cap the default transition delay to 10 ms, which seems to be
 568                  * a reasonable amount of time after which we should reevaluate
 569                  * the frequency.
 570                  */
 571                 return min(latency * LATENCY_MULTIPLIER, (unsigned int)10000);
 572         }
 573
 574         return LATENCY_MULTIPLIER;
 575 }
 576 EXPORT_SYMBOL_GPL(cpufreq_policy_transition_delay_us);
 577
 578 /*********************************************************************
 579  *                          SYSFS INTERFACE                          *
 580  *********************************************************************/
 581 static ssize_t show_boost(struct kobject *kobj,
 582                           struct kobj_attribute *attr, char *buf)
 583 {
 584         return sprintf(buf, "%d\n", cpufreq_driver->boost_enabled);
 585 }
 586
 587 static ssize_t store_boost(struct kobject *kobj, struct kobj_attribute *attr,
 588                            const char *buf, size_t count)
 589 {
 590         int ret, enable;
 591
 592         ret = sscanf(buf, "%d", &enable);
 593         if (ret != 1 || enable < 0 || enable > 1)
 594                 return -EINVAL;
 595
 596         if (cpufreq_boost_trigger_state(enable)) {
 597                 pr_err("%s: Cannot %s BOOST!\n",
 598                        __func__, enable ? "enable" : "disable");
 599                 return -EINVAL;
 600         }
 601
 602         pr_debug("%s: cpufreq BOOST %s\n",
 603                  __func__, enable ? "enabled" : "disabled");
 604
 605         return count;
 606 }
 607 define_one_global_rw(boost);
 608
 609 static struct cpufreq_governor *find_governor(const char *str_governor)
 610 {
 611         struct cpufreq_governor *t;
 612
 613         for_each_governor(t)
 614                 if (!strncasecmp(str_governor, t->name, CPUFREQ_NAME_LEN))
 615                         return t;
 616
 617         return NULL;
 618 }
 619
 620 static int cpufreq_parse_policy(char *str_governor,
 621                                 struct cpufreq_policy *policy)
 622 {
 623         if (!strncasecmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
 624                 policy->policy = CPUFREQ_POLICY_PERFORMANCE;
 625                 return 0;
 626         }
 627         if (!strncasecmp(str_governor, "powersave", CPUFREQ_NAME_LEN)) {
 628                 policy->policy = CPUFREQ_POLICY_POWERSAVE;
 629                 return 0;
 630         }
 631         return -EINVAL;
 632 }
 633
 634 /**
 635  * cpufreq_parse_governor - parse a governor string only for has_target()
 636  */
 637 static int cpufreq_parse_governor(char *str_governor,
 638                                   struct cpufreq_policy *policy)
 639 {
 640         struct cpufreq_governor *t;
 641
 642         mutex_lock(&cpufreq_governor_mutex);
 643
 644         t = find_governor(str_governor);
 645         if (!t) {
 646                 int ret;
 647
 648                 mutex_unlock(&cpufreq_governor_mutex);
 649
 650                 ret = request_module("cpufreq_%s", str_governor);
 651                 if (ret)
 652                         return -EINVAL;
 653
 654                 mutex_lock(&cpufreq_governor_mutex);
 655
 656                 t = find_governor(str_governor);
 657         }
 658         if (t && !try_module_get(t->owner))
 659                 t = NULL;
 660
 661         mutex_unlock(&cpufreq_governor_mutex);
 662
 663         if (t) {
 664                 policy->governor = t;
 665                 return 0;
 666         }
 667
 668         return -EINVAL;
 669 }
 670
 671 /**
 672  * cpufreq_per_cpu_attr_read() / show_##file_name() -
 673  * print out cpufreq information
 674  *
 675  * Write out information from cpufreq_driver->policy[cpu]; object must be
 676  * "unsigned int".
 677  */
 678
 679 #define show_one(file_name, object)                     \
 680 static ssize_t show_##file_name                         \
 681 (struct cpufreq_policy *policy, char *buf)              \
 682 {                                                       \
 683         return sprintf(buf, "%u\n", policy->object);    \
 684 }
 685
 686 show_one(cpuinfo_min_freq, cpuinfo.min_freq);
 687 show_one(cpuinfo_max_freq, cpuinfo.max_freq);
 688 show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
 689 show_one(scaling_min_freq, min);
 690 show_one(scaling_max_freq, max);
 691
 692 __weak unsigned int arch_freq_get_on_cpu(int cpu)
 693 {
 694         return 0;
 695 }
 696
 697 static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf)
 698 {
 699         ssize_t ret;
 700         unsigned int freq;
 701
 702         freq = arch_freq_get_on_cpu(policy->cpu);
 703         if (freq)
 704                 ret = sprintf(buf, "%u\n", freq);
 705         else if (cpufreq_driver && cpufreq_driver->setpolicy &&
 706                         cpufreq_driver->get)
 707                 ret = sprintf(buf, "%u\n", cpufreq_driver->get(policy->cpu));
 708         else
 709                 ret = sprintf(buf, "%u\n", policy->cur);
 710         return ret;
 711 }
 712
 713 /**
 714  * cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
 715  */
 716 #define store_one(file_name, object)                    \
 717 static ssize_t store_##file_name                                        \
 718 (struct cpufreq_policy *policy, const char *buf, size_t count)          \
 719 {                                                                       \
 720         int ret, temp;                                                  \
 721         struct cpufreq_policy new_policy;                               \
 722                                                                         \
 723         memcpy(&new_policy, policy, sizeof(*policy));                   \
 724         new_policy.min = policy->user_policy.min;                       \
 725         new_policy.max = policy->user_policy.max;                       \
 726                                                                         \
 727         ret = sscanf(buf, "%u", &new_policy.object);                    \
 728         if (ret != 1)                                                   \
 729                 return -EINVAL;                                         \
 730                                                                         \
 731         temp = new_policy.object;                                       \
 732         ret = cpufreq_set_policy(policy, &new_policy);          \
 733         if (!ret)                                                       \
 734                 policy->user_policy.object = temp;                      \
 735                                                                         \
 736         return ret ? ret : count;                                       \
 737 }
 738
 739 store_one(scaling_min_freq, min);
 740 store_one(scaling_max_freq, max);
 741
 742 /**
 743  * show_cpuinfo_cur_freq - current CPU frequency as detected by hardware
 744  */
 745 static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
 746                                         char *buf)
 747 {
 748         unsigned int cur_freq = __cpufreq_get(policy);
 749
 750         if (cur_freq)
 751                 return sprintf(buf, "%u\n", cur_freq);
 752
 753         return sprintf(buf, "<unknown>\n");
 754 }
 755
 756 /**
 757  * show_scaling_governor - show the current policy for the specified CPU
 758  */
 759 static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf)
 760 {
 761         if (policy->policy == CPUFREQ_POLICY_POWERSAVE)
 762                 return sprintf(buf, "powersave\n");
 763         else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
 764                 return sprintf(buf, "performance\n");
 765         else if (policy->governor)
 766                 return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n",
 767                                 policy->governor->name);
 768         return -EINVAL;
 769 }
 770
 771 /**
 772  * store_scaling_governor - store policy for the specified CPU
 773  */
 774 static ssize_t store_scaling_governor(struct cpufreq_policy *policy,
 775                                         const char *buf, size_t count)
 776 {
 777         int ret;
 778         char    str_governor[16];
 779         struct cpufreq_policy new_policy;
 780
 781         memcpy(&new_policy, policy, sizeof(*policy));
 782
 783         ret = sscanf(buf, "%15s", str_governor);
 784         if (ret != 1)
 785                 return -EINVAL;
 786
 787         if (cpufreq_driver->setpolicy) {
 788                 if (cpufreq_parse_policy(str_governor, &new_policy))
 789                         return -EINVAL;
 790         } else {
 791                 if (cpufreq_parse_governor(str_governor, &new_policy))
 792                         return -EINVAL;
 793         }
 794
 795         ret = cpufreq_set_policy(policy, &new_policy);
 796
 797         if (new_policy.governor)
 798                 module_put(new_policy.governor->owner);
 799
 800         return ret ? ret : count;
 801 }
 802
 803 /**
 804  * show_scaling_driver - show the cpufreq driver currently loaded
 805  */
 806 static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
 807 {
 808         return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n", cpufreq_driver->name);
 809 }
 810
 811 /**
 812  * show_scaling_available_governors - show the available CPUfreq governors
 813  */
 814 static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
 815                                                 char *buf)
 816 {
 817         ssize_t i = 0;
 818         struct cpufreq_governor *t;
 819
 820         if (!has_target()) {
 821                 i += sprintf(buf, "performance powersave");
 822                 goto out;
 823         }
 824
 825         for_each_governor(t) {
 826                 if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
 827                     - (CPUFREQ_NAME_LEN + 2)))
 828                         goto out;
 829                 i += scnprintf(&buf[i], CPUFREQ_NAME_PLEN, "%s ", t->name);
 830         }
 831 out:
 832         i += sprintf(&buf[i], "\n");
 833         return i;
 834 }
 835
 836 ssize_t cpufreq_show_cpus(const struct cpumask *mask, char *buf)
 837 {
 838         ssize_t i = 0;
 839         unsigned int cpu;
 840
 841         for_each_cpu(cpu, mask) {
 842                 if (i)
 843                         i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), " ");
 844                 i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u", cpu);
 845                 if (i >= (PAGE_SIZE - 5))
 846                         break;
 847         }
 848         i += sprintf(&buf[i], "\n");
 849         return i;
 850 }
 851 EXPORT_SYMBOL_GPL(cpufreq_show_cpus);
 852
 853 /**
 854  * show_related_cpus - show the CPUs affected by each transition even if
 855  * hw coordination is in use
 856  */
 857 static ssize_t show_related_cpus(struct cpufreq_policy *policy, char *buf)
 858 {
 859         return cpufreq_show_cpus(policy->related_cpus, buf);
 860 }
 861
 862 /**
 863  * show_affected_cpus - show the CPUs affected by each transition
 864  */
 865 static ssize_t show_affected_cpus(struct cpufreq_policy *policy, char *buf)
 866 {
 867         return cpufreq_show_cpus(policy->cpus, buf);
 868 }
 869
 870 static ssize_t store_scaling_setspeed(struct cpufreq_policy *policy,
 871                                         const char *buf, size_t count)
 872 {
 873         unsigned int freq = 0;
 874         unsigned int ret;
 875
 876         if (!policy->governor || !policy->governor->store_setspeed)
 877                 return -EINVAL;
 878
 879         ret = sscanf(buf, "%u", &freq);
 880         if (ret != 1)
 881                 return -EINVAL;
 882
 883         policy->governor->store_setspeed(policy, freq);
 884
 885         return count;
 886 }
 887
 888 static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
 889 {
 890         if (!policy->governor || !policy->governor->show_setspeed)
 891                 return sprintf(buf, "<unsupported>\n");
 892
 893         return policy->governor->show_setspeed(policy, buf);
 894 }
 895
 896 /**
 897  * show_bios_limit - show the current cpufreq HW/BIOS limitation
 898  */
 899 static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
 900 {
 901         unsigned int limit;
 902         int ret;
 903         ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
 904         if (!ret)
 905                 return sprintf(buf, "%u\n", limit);
 906         return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
 907 }
 908
 909 cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);
 910 cpufreq_freq_attr_ro(cpuinfo_min_freq);
 911 cpufreq_freq_attr_ro(cpuinfo_max_freq);
 912 cpufreq_freq_attr_ro(cpuinfo_transition_latency);
 913 cpufreq_freq_attr_ro(scaling_available_governors);
 914 cpufreq_freq_attr_ro(scaling_driver);
 915 cpufreq_freq_attr_ro(scaling_cur_freq);
 916 cpufreq_freq_attr_ro(bios_limit);
 917 cpufreq_freq_attr_ro(related_cpus);
 918 cpufreq_freq_attr_ro(affected_cpus);
 919 cpufreq_freq_attr_rw(scaling_min_freq);
 920 cpufreq_freq_attr_rw(scaling_max_freq);
 921 cpufreq_freq_attr_rw(scaling_governor);
 922 cpufreq_freq_attr_rw(scaling_setspeed);
 923
 924 static struct attribute *default_attrs[] = {
 925         &cpuinfo_min_freq.attr,
 926         &cpuinfo_max_freq.attr,
 927         &cpuinfo_transition_latency.attr,
 928         &scaling_min_freq.attr,
 929         &scaling_max_freq.attr,
 930         &affected_cpus.attr,
 931         &related_cpus.attr,
 932         &scaling_governor.attr,
 933         &scaling_driver.attr,
 934         &scaling_available_governors.attr,
 935         &scaling_setspeed.attr,
 936         NULL
 937 };
 938
 939 #define to_policy(k) container_of(k, struct cpufreq_policy, kobj)
 940 #define to_attr(a) container_of(a, struct freq_attr, attr)
 941
 942 static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
 943 {
 944         struct cpufreq_policy *policy = to_policy(kobj);
 945         struct freq_attr *fattr = to_attr(attr);
 946         ssize_t ret;
 947
 948         down_read(&policy->rwsem);
 949         ret = fattr->show(policy, buf);
 950         up_read(&policy->rwsem);
 951
 952         return ret;
 953 }
 954
 955 static ssize_t store(struct kobject *kobj, struct attribute *attr,
 956                      const char *buf, size_t count)
 957 {
 958         struct cpufreq_policy *policy = to_policy(kobj);
 959         struct freq_attr *fattr = to_attr(attr);
 960         ssize_t ret = -EINVAL;
 961
 962         /*
 963          * cpus_read_trylock() is used here to work around a circular lock
 964          * dependency problem with respect to the cpufreq_register_driver().
 965          */
 966         if (!cpus_read_trylock())
 967                 return -EBUSY;
 968
 969         if (cpu_online(policy->cpu)) {
 970                 down_write(&policy->rwsem);
 971                 ret = fattr->store(policy, buf, count);
 972                 up_write(&policy->rwsem);
 973         }
 974
 975         cpus_read_unlock();
 976
 977         return ret;
 978 }
 979
 980 static void cpufreq_sysfs_release(struct kobject *kobj)
 981 {
 982         struct cpufreq_policy *policy = to_policy(kobj);
 983         pr_debug("last reference is dropped\n");
 984         complete(&policy->kobj_unregister);
 985 }
 986
 987 static const struct sysfs_ops sysfs_ops = {
 988         .show   = show,
 989         .store  = store,
 990 };
 991
 992 static struct kobj_type ktype_cpufreq = {
 993         .sysfs_ops      = &sysfs_ops,
 994         .default_attrs  = default_attrs,
 995         .release        = cpufreq_sysfs_release,
 996 };
 997
 998 static void add_cpu_dev_symlink(struct cpufreq_policy *policy, unsigned int cpu)
 999 {
1000         struct device *dev = get_cpu_device(cpu);
1001
1002         if (!dev)
1003                 return;
1004
1005         if (cpumask_test_and_set_cpu(cpu, policy->real_cpus))
1006                 return;
1007
1008         dev_dbg(dev, "%s: Adding symlink\n", __func__);
1009         if (sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq"))
1010                 dev_err(dev, "cpufreq symlink creation failed\n");
1011 }
1012
1013 static void remove_cpu_dev_symlink(struct cpufreq_policy *policy,
1014                                    struct device *dev)
1015 {
1016         dev_dbg(dev, "%s: Removing symlink\n", __func__);
1017         sysfs_remove_link(&dev->kobj, "cpufreq");
1018 }
1019
1020 static int cpufreq_add_dev_interface(struct cpufreq_policy *policy)
1021 {
1022         struct freq_attr **drv_attr;
1023         int ret = 0;
1024
1025         /* set up files for this cpu device */
1026         drv_attr = cpufreq_driver->attr;
1027         while (drv_attr && *drv_attr) {
1028                 ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
1029                 if (ret)
1030                         return ret;
1031                 drv_attr++;
1032         }
1033         if (cpufreq_driver->get) {
1034                 ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
1035                 if (ret)
1036                         return ret;
1037         }
1038
1039         ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
1040         if (ret)
1041                 return ret;
1042
1043         if (cpufreq_driver->bios_limit) {
1044                 ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
1045                 if (ret)
1046                         return ret;
1047         }
1048
1049         return 0;
1050 }
1051
1052 __weak struct cpufreq_governor *cpufreq_default_governor(void)
1053 {
1054         return NULL;
1055 }
1056
1057 static int cpufreq_init_policy(struct cpufreq_policy *policy)
1058 {
1059         struct cpufreq_governor *gov = NULL, *def_gov = NULL;
1060         struct cpufreq_policy new_policy;
1061
1062         memcpy(&new_policy, policy, sizeof(*policy));
1063
1064         def_gov = cpufreq_default_governor();
1065
1066         if (has_target()) {
1067                 /*
1068                  * Update governor of new_policy to the governor used before
1069                  * hotplug
1070                  */
1071                 gov = find_governor(policy->last_governor);
1072                 if (gov) {
1073                         pr_debug("Restoring governor %s for cpu %d\n",
1074                                 policy->governor->name, policy->cpu);
1075                 } else {
1076                         if (!def_gov)
1077                                 return -ENODATA;
1078                         gov = def_gov;
1079                 }
1080                 new_policy.governor = gov;
1081         } else {
1082                 /* Use the default policy if there is no last_policy. */
1083                 if (policy->last_policy) {
1084                         new_policy.policy = policy->last_policy;
1085                 } else {
1086                         if (!def_gov)
1087                                 return -ENODATA;
1088                         cpufreq_parse_policy(def_gov->name, &new_policy);
1089                 }
1090         }
1091
1092         return cpufreq_set_policy(policy, &new_policy);
1093 }
1094
1095 static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
1096 {
1097         int ret = 0;
1098
1099         /* Has this CPU been taken care of already? */
1100         if (cpumask_test_cpu(cpu, policy->cpus))
1101                 return 0;
1102
1103         down_write(&policy->rwsem);
1104         if (has_target())
1105                 cpufreq_stop_governor(policy);
1106
1107         cpumask_set_cpu(cpu, policy->cpus);
1108
1109         if (has_target()) {
1110                 ret = cpufreq_start_governor(policy);
1111                 if (ret)
1112                         pr_err("%s: Failed to start governor\n", __func__);
1113         }
1114         up_write(&policy->rwsem);
1115         return ret;
1116 }
1117
1118 static void handle_update(struct work_struct *work)
1119 {
1120         struct cpufreq_policy *policy =
1121                 container_of(work, struct cpufreq_policy, update);
1122         unsigned int cpu = policy->cpu;
1123         pr_debug("handle_update for cpu %u called\n", cpu);
1124         cpufreq_update_policy(cpu);
1125 }
1126
1127 static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
1128 {
1129         struct cpufreq_policy *policy;
1130         int ret;
1131
1132         policy = kzalloc(sizeof(*policy), GFP_KERNEL);
1133         if (!policy)
1134                 return NULL;
1135
1136         if (!alloc_cpumask_var(&policy->cpus, GFP_KERNEL))
1137                 goto err_free_policy;
1138
1139         if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL))
1140                 goto err_free_cpumask;
1141
1142         if (!zalloc_cpumask_var(&policy->real_cpus, GFP_KERNEL))
1143                 goto err_free_rcpumask;
1144
1145         ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
1146                                    cpufreq_global_kobject, "policy%u", cpu);
1147         if (ret) {
1148                 pr_err("%s: failed to init policy->kobj: %d\n", __func__, ret);
1149                 /*
1150                  * The entire policy object will be freed below, but the extra
1151                  * memory allocated for the kobject name needs to be freed by
1152                  * releasing the kobject.
1153                  */
1154                 kobject_put(&policy->kobj);
1155                 goto err_free_real_cpus;
1156         }
1157
1158         INIT_LIST_HEAD(&policy->policy_list);
1159         init_rwsem(&policy->rwsem);
1160         spin_lock_init(&policy->transition_lock);
1161         init_waitqueue_head(&policy->transition_wait);
1162         init_completion(&policy->kobj_unregister);
1163         INIT_WORK(&policy->update, handle_update);
1164
1165         policy->cpu = cpu;
1166         return policy;
1167
1168 err_free_real_cpus:
1169         free_cpumask_var(policy->real_cpus);
1170 err_free_rcpumask:
1171         free_cpumask_var(policy->related_cpus);
1172 err_free_cpumask:
1173         free_cpumask_var(policy->cpus);
1174 err_free_policy:
1175         kfree(policy);
1176
1177         return NULL;
1178 }
1179
1180 static void cpufreq_policy_put_kobj(struct cpufreq_policy *policy)
1181 {
1182         struct kobject *kobj;
1183         struct completion *cmp;
1184
1185         down_write(&policy->rwsem);
1186         cpufreq_stats_free_table(policy);
1187         kobj = &policy->kobj;
1188         cmp = &policy->kobj_unregister;
1189         up_write(&policy->rwsem);
1190         kobject_put(kobj);
1191
1192         /*
1193          * We need to make sure that the underlying kobj is
1194          * actually not referenced anymore by anybody before we
1195          * proceed with unloading.
1196          */
1197         pr_debug("waiting for dropping of refcount\n");
1198         wait_for_completion(cmp);
1199         pr_debug("wait complete\n");
1200 }
1201
1202 static void cpufreq_policy_free(struct cpufreq_policy *policy)
1203 {
1204         unsigned long flags;
1205         int cpu;
1206
1207         /* Remove policy from list */
1208         write_lock_irqsave(&cpufreq_driver_lock, flags);
1209         list_del(&policy->policy_list);
1210
1211         for_each_cpu(cpu, policy->related_cpus)
1212                 per_cpu(cpufreq_cpu_data, cpu) = NULL;
1213         write_unlock_irqrestore(&cpufreq_driver_lock, flags);
1214
1215         cpufreq_policy_put_kobj(policy);
1216         free_cpumask_var(policy->real_cpus);
1217         free_cpumask_var(policy->related_cpus);
1218         free_cpumask_var(policy->cpus);
1219         kfree(policy);
1220 }
1221
1222 static int cpufreq_online(unsigned int cpu)
1223 {
1224         struct cpufreq_policy *policy;
1225         bool new_policy;
1226         unsigned long flags;
1227         unsigned int j;
1228         int ret;
1229
1230         pr_debug("%s: bringing CPU%u online\n", __func__, cpu);
1231
1232         /* Check if this CPU already has a policy to manage it */
1233         policy = per_cpu(cpufreq_cpu_data, cpu);
1234         if (policy) {
1235                 WARN_ON(!cpumask_test_cpu(cpu, policy->related_cpus));
1236                 if (!policy_is_inactive(policy))
1237                         return cpufreq_add_policy_cpu(policy, cpu);
1238
1239                 /* This is the only online CPU for the policy.  Start over. */
1240                 new_policy = false;
1241                 down_write(&policy->rwsem);
1242                 policy->cpu = cpu;
1243                 policy->governor = NULL;
1244                 up_write(&policy->rwsem);
1245         } else {
1246                 new_policy = true;
1247                 policy = cpufreq_policy_alloc(cpu);
1248                 if (!policy)
1249                         return -ENOMEM;
1250         }
1251
1252         if (!new_policy && cpufreq_driver->online) {
1253                 ret = cpufreq_driver->online(policy);
1254                 if (ret) {
1255                         pr_debug("%s: %d: initialization failed\n", __func__,
1256                                  __LINE__);
1257                         goto out_exit_policy;
1258                 }
1259
1260                 /* Recover policy->cpus using related_cpus */
1261                 cpumask_copy(policy->cpus, policy->related_cpus);
1262         } else {
1263                 cpumask_copy(policy->cpus, cpumask_of(cpu));
1264
1265                 /*
1266                  * Call driver. From then on the cpufreq must be able
1267                  * to accept all calls to ->verify and ->setpolicy for this CPU.
1268                  */
1269                 ret = cpufreq_driver->init(policy);
1270                 if (ret) {
1271                         pr_debug("%s: %d: initialization failed\n", __func__,
1272                                  __LINE__);
1273                         goto out_free_policy;
1274                 }
1275
1276                 ret = cpufreq_table_validate_and_sort(policy);
1277                 if (ret)
1278                         goto out_exit_policy;
1279
1280                 /* related_cpus should at least include policy->cpus. */
1281                 cpumask_copy(policy->related_cpus, policy->cpus);
1282         }
1283
1284         down_write(&policy->rwsem);
1285         /*
1286          * affected cpus must always be the one, which are online. We aren't
1287          * managing offline cpus here.
1288          */
1289         cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);
1290
1291         if (new_policy) {
1292                 policy->user_policy.min = policy->min;
1293                 policy->user_policy.max = policy->max;
1294
1295                 for_each_cpu(j, policy->related_cpus) {
1296                         per_cpu(cpufreq_cpu_data, j) = policy;
1297                         add_cpu_dev_symlink(policy, j);
1298                 }
1299         } else {
1300                 policy->min = policy->user_policy.min;
1301                 policy->max = policy->user_policy.max;
1302         }
1303
1304         if (cpufreq_driver->get && has_target()) {
1305                 policy->cur = cpufreq_driver->get(policy->cpu);
1306                 if (!policy->cur) {
1307                         pr_err("%s: ->get() failed\n", __func__);
1308                         goto out_destroy_policy;
1309                 }
1310         }
1311
1312         /*
1313          * Sometimes boot loaders set CPU frequency to a value outside of
1314          * frequency table present with cpufreq core. In such cases CPU might be
1315          * unstable if it has to run on that frequency for long duration of time
1316          * and so its better to set it to a frequency which is specified in
1317          * freq-table. This also makes cpufreq stats inconsistent as
1318          * cpufreq-stats would fail to register because current frequency of CPU
1319          * isn't found in freq-table.
1320          *
1321          * Because we don't want this change to effect boot process badly, we go
1322          * for the next freq which is >= policy->cur ('cur' must be set by now,
1323          * otherwise we will end up setting freq to lowest of the table as 'cur'
1324          * is initialized to zero).
1325          *
1326          * We are passing target-freq as "policy->cur - 1" otherwise
1327          * __cpufreq_driver_target() would simply fail, as policy->cur will be
1328          * equal to target-freq.
1329          */
1330         if ((cpufreq_driver->flags & CPUFREQ_NEED_INITIAL_FREQ_CHECK)
1331             && has_target()) {
1332                 /* Are we running at unknown frequency ? */
1333                 ret = cpufreq_frequency_table_get_index(policy, policy->cur);
1334                 if (ret == -EINVAL) {
1335                         /* Warn user and fix it */
1336                         pr_warn("%s: CPU%d: Running at unlisted freq: %u KHz\n",
1337                                 __func__, policy->cpu, policy->cur);
1338                         ret = __cpufreq_driver_target(policy, policy->cur - 1,
1339                                 CPUFREQ_RELATION_L);
1340
1341                         /*
1342                          * Reaching here after boot in a few seconds may not
1343                          * mean that system will remain stable at "unknown"
1344                          * frequency for longer duration. Hence, a BUG_ON().
1345                          */
1346                         BUG_ON(ret);
1347                         pr_warn("%s: CPU%d: Unlisted initial frequency changed to: %u KHz\n",
1348                                 __func__, policy->cpu, policy->cur);
1349                 }
1350         }
1351
1352         if (new_policy) {
1353                 ret = cpufreq_add_dev_interface(policy);
1354                 if (ret)
1355                         goto out_destroy_policy;
1356
1357                 cpufreq_stats_create_table(policy);
1358
1359                 write_lock_irqsave(&cpufreq_driver_lock, flags);
1360                 list_add(&policy->policy_list, &cpufreq_policy_list);
1361                 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
1362         }
1363
1364         ret = cpufreq_init_policy(policy);
1365         if (ret) {
1366                 pr_err("%s: Failed to initialize policy for cpu: %d (%d)\n",
1367                        __func__, cpu, ret);
1368                 goto out_destroy_policy;
1369         }
1370
1371         up_write(&policy->rwsem);
1372
1373         kobject_uevent(&policy->kobj, KOBJ_ADD);
1374
1375         /* Callback for handling stuff after policy is ready */
1376         if (cpufreq_driver->ready)
1377                 cpufreq_driver->ready(policy);
1378
1379         if (cpufreq_thermal_control_enabled(cpufreq_driver))
1380                 policy->cdev = of_cpufreq_cooling_register(policy);
1381
1382         pr_debug("initialization complete\n");
1383
1384         return 0;
1385
1386 out_destroy_policy:
1387         for_each_cpu(j, policy->real_cpus)
1388                 remove_cpu_dev_symlink(policy, get_cpu_device(j));
1389
1390         up_write(&policy->rwsem);
1391
1392 out_exit_policy:
1393         if (cpufreq_driver->exit)
1394                 cpufreq_driver->exit(policy);
1395
1396 out_free_policy:
1397         cpufreq_policy_free(policy);
1398         return ret;
1399 }
1400
1401 /**
1402  * cpufreq_add_dev - the cpufreq interface for a CPU device.
1403  * @dev: CPU device.
1404  * @sif: Subsystem interface structure pointer (not used)
1405  */
1406 static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
1407 {
1408         struct cpufreq_policy *policy;
1409         unsigned cpu = dev->id;
1410         int ret;
1411
1412         dev_dbg(dev, "%s: adding CPU%u\n", __func__, cpu);
1413
1414         if (cpu_online(cpu)) {
1415                 ret = cpufreq_online(cpu);
1416                 if (ret)
1417                         return ret;
1418         }
1419
1420         /* Create sysfs link on CPU registration */
1421         policy = per_cpu(cpufreq_cpu_data, cpu);
1422         if (policy)
1423                 add_cpu_dev_symlink(policy, cpu);
1424
1425         return 0;
1426 }
1427
1428 static int cpufreq_offline(unsigned int cpu)
1429 {
1430         struct cpufreq_policy *policy;
1431         int ret;
1432
1433         pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
1434
1435         policy = cpufreq_cpu_get_raw(cpu);
1436         if (!policy) {
1437                 pr_debug("%s: No cpu_data found\n", __func__);
1438                 return 0;
1439         }
1440
1441         down_write(&policy->rwsem);
1442         if (has_target())
1443                 cpufreq_stop_governor(policy);
1444
1445         cpumask_clear_cpu(cpu, policy->cpus);
1446
1447         if (policy_is_inactive(policy)) {
1448                 if (has_target())
1449                         strncpy(policy->last_governor, policy->governor->name,
1450                                 CPUFREQ_NAME_LEN);
1451                 else
1452                         policy->last_policy = policy->policy;
1453         } else if (cpu == policy->cpu) {
1454                 /* Nominate new CPU */
1455                 policy->cpu = cpumask_any(policy->cpus);
1456         }
1457
1458         /* Start governor again for active policy */
1459         if (!policy_is_inactive(policy)) {
1460                 if (has_target()) {
1461                         ret = cpufreq_start_governor(policy);
1462                         if (ret)
1463                                 pr_err("%s: Failed to start governor\n", __func__);
1464                 }
1465
1466                 goto unlock;
1467         }
1468
1469         if (cpufreq_thermal_control_enabled(cpufreq_driver)) {
1470                 cpufreq_cooling_unregister(policy->cdev);
1471                 policy->cdev = NULL;
1472         }
1473
1474         if (cpufreq_driver->stop_cpu)
1475                 cpufreq_driver->stop_cpu(policy);
1476
1477         if (has_target())
1478                 cpufreq_exit_governor(policy);
1479
1480         /*
1481          * Perform the ->offline() during light-weight tear-down, as
1482          * that allows fast recovery when the CPU comes back.
1483          */
1484         if (cpufreq_driver->offline) {
1485                 cpufreq_driver->offline(policy);
1486         } else if (cpufreq_driver->exit) {
1487                 cpufreq_driver->exit(policy);
1488                 policy->freq_table = NULL;
1489         }
1490
1491 unlock:
1492         up_write(&policy->rwsem);
1493         return 0;
1494 }
1495
1496 /**
1497  * cpufreq_remove_dev - remove a CPU device
1498  *
1499  * Removes the cpufreq interface for a CPU device.
1500  */
1501 static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
1502 {
1503         unsigned int cpu = dev->id;
1504         struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
1505
1506         if (!policy)
1507                 return;
1508
1509         if (cpu_online(cpu))
1510                 cpufreq_offline(cpu);
1511
1512         cpumask_clear_cpu(cpu, policy->real_cpus);
1513         remove_cpu_dev_symlink(policy, dev);
1514
1515         if (cpumask_empty(policy->real_cpus)) {
1516                 /* We did light-weight exit earlier, do full tear down now */
1517                 if (cpufreq_driver->offline)
1518                         cpufreq_driver->exit(policy);
1519
1520                 cpufreq_policy_free(policy);
1521         }
1522 }
1523
1524 /**
1525  *      cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're
1526  *      in deep trouble.
1527  *      @policy: policy managing CPUs
1528  *      @new_freq: CPU frequency the CPU actually runs at
1529  *
1530  *      We adjust to current frequency first, and need to clean up later.
1531  *      So either call to cpufreq_update_policy() or schedule handle_update()).
1532  */
1533 static void cpufreq_out_of_sync(struct cpufreq_policy *policy,
1534                                 unsigned int new_freq)
1535 {
1536         struct cpufreq_freqs freqs;
1537
1538         pr_debug("Warning: CPU frequency out of sync: cpufreq and timing core thinks of %u, is %u kHz\n",
1539                  policy->cur, new_freq);
1540
1541         freqs.old = policy->cur;
1542         freqs.new = new_freq;
1543
1544         cpufreq_freq_transition_begin(policy, &freqs);
1545         cpufreq_freq_transition_end(policy, &freqs, 0);
1546 }
1547
1548 /**
1549  * cpufreq_quick_get - get the CPU frequency (in kHz) from policy->cur
1550  * @cpu: CPU number
1551  *
1552  * This is the last known freq, without actually getting it from the driver.
1553  * Return value will be same as what is shown in scaling_cur_freq in sysfs.
1554  */
1555 unsigned int cpufreq_quick_get(unsigned int cpu)
1556 {
1557         struct cpufreq_policy *policy;
1558         unsigned int ret_freq = 0;
1559         unsigned long flags;
1560
1561         read_lock_irqsave(&cpufreq_driver_lock, flags);
1562
1563         if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get) {
1564                 ret_freq = cpufreq_driver->get(cpu);
1565                 read_unlock_irqrestore(&cpufreq_driver_lock, flags);
1566                 return ret_freq;
1567         }
1568
1569         read_unlock_irqrestore(&cpufreq_driver_lock, flags);
1570
1571         policy = cpufreq_cpu_get(cpu);
1572         if (policy) {
1573                 ret_freq = policy->cur;
1574                 cpufreq_cpu_put(policy);
1575         }
1576
1577         return ret_freq;
1578 }
1579 EXPORT_SYMBOL(cpufreq_quick_get);
1580
1581 /**
1582  * cpufreq_quick_get_max - get the max reported CPU frequency for this CPU
1583  * @cpu: CPU number
1584  *
1585  * Just return the max possible frequency for a given CPU.
1586  */
1587 unsigned int cpufreq_quick_get_max(unsigned int cpu)
1588 {
1589         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
1590         unsigned int ret_freq = 0;
1591
1592         if (policy) {
1593                 ret_freq = policy->max;
1594                 cpufreq_cpu_put(policy);
1595         }
1596
1597         return ret_freq;
1598 }
1599 EXPORT_SYMBOL(cpufreq_quick_get_max);
1600
1601 static unsigned int __cpufreq_get(struct cpufreq_policy *policy)
1602 {
1603         unsigned int ret_freq = 0;
1604
1605         if (unlikely(policy_is_inactive(policy)))
1606                 return ret_freq;
1607
1608         ret_freq = cpufreq_driver->get(policy->cpu);
1609
1610         /*
1611          * If fast frequency switching is used with the given policy, the check
1612          * against policy->cur is pointless, so skip it in that case too.
1613          */
1614         if (policy->fast_switch_enabled)
1615                 return ret_freq;
1616
1617         if (has_target() && ret_freq && policy->cur) {
1618                 /* verify no discrepancy between actual and
1619                                         saved value exists */
1620                 if (unlikely(ret_freq != policy->cur)) {
1621                         cpufreq_out_of_sync(policy, ret_freq);
1622                         schedule_work(&policy->update);
1623                 }
1624         }
1625
1626         return ret_freq;
1627 }
1628
1629 /**
1630  * cpufreq_get - get the current CPU frequency (in kHz)
1631  * @cpu: CPU number
1632  *
1633  * Get the CPU current (static) CPU frequency
1634  */
1635 unsigned int cpufreq_get(unsigned int cpu)
1636 {
1637         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
1638         unsigned int ret_freq = 0;
1639
1640         if (policy) {
1641                 down_read(&policy->rwsem);
1642                 if (cpufreq_driver->get)
1643                         ret_freq = __cpufreq_get(policy);
1644                 up_read(&policy->rwsem);
1645
1646                 cpufreq_cpu_put(policy);
1647         }
1648
1649         return ret_freq;
1650 }
1651 EXPORT_SYMBOL(cpufreq_get);
1652
1653 static unsigned int cpufreq_update_current_freq(struct cpufreq_policy *policy)
1654 {
1655         unsigned int new_freq;
1656
1657         new_freq = cpufreq_driver->get(policy->cpu);
1658         if (!new_freq)
1659                 return 0;
1660
1661         if (!policy->cur) {
1662                 pr_debug("cpufreq: Driver did not initialize current freq\n");
1663                 policy->cur = new_freq;
1664         } else if (policy->cur != new_freq && has_target()) {
1665                 cpufreq_out_of_sync(policy, new_freq);
1666         }
1667
1668         return new_freq;
1669 }
1670
1671 static struct subsys_interface cpufreq_interface = {
1672         .name           = "cpufreq",
1673         .subsys         = &cpu_subsys,
1674         .add_dev        = cpufreq_add_dev,
1675         .remove_dev     = cpufreq_remove_dev,
1676 };
1677
1678 /*
1679  * In case platform wants some specific frequency to be configured
1680  * during suspend..
1681  */
1682 int cpufreq_generic_suspend(struct cpufreq_policy *policy)
1683 {
1684         int ret;
1685
1686         if (!policy->suspend_freq) {
1687                 pr_debug("%s: suspend_freq not defined\n", __func__);
1688                 return 0;
1689         }
1690
1691         pr_debug("%s: Setting suspend-freq: %u\n", __func__,
1692                         policy->suspend_freq);
1693
1694         ret = __cpufreq_driver_target(policy, policy->suspend_freq,
1695                         CPUFREQ_RELATION_H);
1696         if (ret)
1697                 pr_err("%s: unable to set suspend-freq: %u. err: %d\n",
1698                                 __func__, policy->suspend_freq, ret);
1699
1700         return ret;
1701 }
1702 EXPORT_SYMBOL(cpufreq_generic_suspend);
1703
1704 /**
1705  * cpufreq_suspend() - Suspend CPUFreq governors
1706  *
1707  * Called during system wide Suspend/Hibernate cycles for suspending governors
1708  * as some platforms can't change frequency after this point in suspend cycle.
1709  * Because some of the devices (like: i2c, regulators, etc) they use for
1710  * changing frequency are suspended quickly after this point.
1711  */
1712 void cpufreq_suspend(void)
1713 {
1714         struct cpufreq_policy *policy;
1715
1716         if (!cpufreq_driver)
1717                 return;
1718
1719         if (!has_target() && !cpufreq_driver->suspend)
1720                 goto suspend;
1721
1722         pr_debug("%s: Suspending Governors\n", __func__);
1723
1724         for_each_active_policy(policy) {
1725                 if (has_target()) {
1726                         down_write(&policy->rwsem);
1727                         cpufreq_stop_governor(policy);
1728                         up_write(&policy->rwsem);
1729                 }
1730
1731                 if (cpufreq_driver->suspend && cpufreq_driver->suspend(policy))
1732                         pr_err("%s: Failed to suspend driver: %p\n", __func__,
1733                                 policy);
1734         }
1735
1736 suspend:
1737         cpufreq_suspended = true;
1738 }
1739
1740 /**
1741  * cpufreq_resume() - Resume CPUFreq governors
1742  *
1743  * Called during system wide Suspend/Hibernate cycle for resuming governors that
1744  * are suspended with cpufreq_suspend().
1745  */
1746 void cpufreq_resume(void)
1747 {
1748         struct cpufreq_policy *policy;
1749         int ret;
1750
1751         if (!cpufreq_driver)
1752                 return;
1753
1754         if (unlikely(!cpufreq_suspended))
1755                 return;
1756
1757         cpufreq_suspended = false;
1758
1759         if (!has_target() && !cpufreq_driver->resume)
1760                 return;
1761
1762         pr_debug("%s: Resuming Governors\n", __func__);
1763
1764         for_each_active_policy(policy) {
1765                 if (cpufreq_driver->resume && cpufreq_driver->resume(policy)) {
1766                         pr_err("%s: Failed to resume driver: %p\n", __func__,
1767                                 policy);
1768                 } else if (has_target()) {
1769                         down_write(&policy->rwsem);
1770                         ret = cpufreq_start_governor(policy);
1771                         up_write(&policy->rwsem);
1772
1773                         if (ret)
1774                                 pr_err("%s: Failed to start governor for policy: %p\n",
1775                                        __func__, policy);
1776                 }
1777         }
1778 }
1779
1780 /**
1781  *      cpufreq_get_current_driver - return current driver's name
1782  *
1783  *      Return the name string of the currently loaded cpufreq driver
1784  *      or NULL, if none.
1785  */
1786 const char *cpufreq_get_current_driver(void)
1787 {
1788         if (cpufreq_driver)
1789                 return cpufreq_driver->name;
1790
1791         return NULL;
1792 }
1793 EXPORT_SYMBOL_GPL(cpufreq_get_current_driver);
1794
1795 /**
1796  *      cpufreq_get_driver_data - return current driver data
1797  *
1798  *      Return the private data of the currently loaded cpufreq
1799  *      driver, or NULL if no cpufreq driver is loaded.
1800  */
1801 void *cpufreq_get_driver_data(void)
1802 {
1803         if (cpufreq_driver)
1804                 return cpufreq_driver->driver_data;
1805
1806         return NULL;
1807 }
1808 EXPORT_SYMBOL_GPL(cpufreq_get_driver_data);
1809
1810 /*********************************************************************
1811  *                     NOTIFIER LISTS INTERFACE                      *
1812  *********************************************************************/
1813
1814 /**
1815  *      cpufreq_register_notifier - register a driver with cpufreq
1816  *      @nb: notifier function to register
1817  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
1818  *
1819  *      Add a driver to one of two lists: either a list of drivers that
1820  *      are notified about clock rate changes (once before and once after
1821  *      the transition), or a list of drivers that are notified about
1822  *      changes in cpufreq policy.
1823  *
1824  *      This function may sleep, and has the same return conditions as
1825  *      blocking_notifier_chain_register.
1826  */
1827 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
1828 {
1829         int ret;
1830
1831         if (cpufreq_disabled())
1832                 return -EINVAL;
1833
1834         switch (list) {
1835         case CPUFREQ_TRANSITION_NOTIFIER:
1836                 mutex_lock(&cpufreq_fast_switch_lock);
1837
1838                 if (cpufreq_fast_switch_count > 0) {
1839                         mutex_unlock(&cpufreq_fast_switch_lock);
1840                         return -EBUSY;
1841                 }
1842                 ret = srcu_notifier_chain_register(
1843                                 &cpufreq_transition_notifier_list, nb);
1844                 if (!ret)
1845                         cpufreq_fast_switch_count--;
1846
1847                 mutex_unlock(&cpufreq_fast_switch_lock);
1848                 break;
1849         case CPUFREQ_POLICY_NOTIFIER:
1850                 ret = blocking_notifier_chain_register(
1851                                 &cpufreq_policy_notifier_list, nb);
1852                 break;
1853         default:
1854                 ret = -EINVAL;
1855         }
1856
1857         return ret;
1858 }
1859 EXPORT_SYMBOL(cpufreq_register_notifier);
1860
1861 /**
1862  *      cpufreq_unregister_notifier - unregister a driver with cpufreq
1863  *      @nb: notifier block to be unregistered
1864  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
1865  *
1866  *      Remove a driver from the CPU frequency notifier list.
1867  *
1868  *      This function may sleep, and has the same return conditions as
1869  *      blocking_notifier_chain_unregister.
1870  */
1871 int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
1872 {
1873         int ret;
1874
1875         if (cpufreq_disabled())
1876                 return -EINVAL;
1877
1878         switch (list) {
1879         case CPUFREQ_TRANSITION_NOTIFIER:
1880                 mutex_lock(&cpufreq_fast_switch_lock);
1881
1882                 ret = srcu_notifier_chain_unregister(
1883                                 &cpufreq_transition_notifier_list, nb);
1884                 if (!ret && !WARN_ON(cpufreq_fast_switch_count >= 0))
1885                         cpufreq_fast_switch_count++;
1886
1887                 mutex_unlock(&cpufreq_fast_switch_lock);
1888                 break;
1889         case CPUFREQ_POLICY_NOTIFIER:
1890                 ret = blocking_notifier_chain_unregister(
1891                                 &cpufreq_policy_notifier_list, nb);
1892                 break;
1893         default:
1894                 ret = -EINVAL;
1895         }
1896
1897         return ret;
1898 }
1899 EXPORT_SYMBOL(cpufreq_unregister_notifier);
1900
1901
1902 /*********************************************************************
1903  *                              GOVERNORS                            *
1904  *********************************************************************/
1905
1906 /**
1907  * cpufreq_driver_fast_switch - Carry out a fast CPU frequency switch.
1908  * @policy: cpufreq policy to switch the frequency for.
1909  * @target_freq: New frequency to set (may be approximate).
1910  *
1911  * Carry out a fast frequency switch without sleeping.
1912  *
1913  * The driver's ->fast_switch() callback invoked by this function must be
1914  * suitable for being called from within RCU-sched read-side critical sections
1915  * and it is expected to select the minimum available frequency greater than or
1916  * equal to @target_freq (CPUFREQ_RELATION_L).
1917  *
1918  * This function must not be called if policy->fast_switch_enabled is unset.
1919  *
1920  * Governors calling this function must guarantee that it will never be invoked
1921  * twice in parallel for the same policy and that it will never be called in
1922  * parallel with either ->target() or ->target_index() for the same policy.
1923  *
1924  * Returns the actual frequency set for the CPU.
1925  *
1926  * If 0 is returned by the driver's ->fast_switch() callback to indicate an
1927  * error condition, the hardware configuration must be preserved.
1928  */
1929 unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
1930                                         unsigned int target_freq)
1931 {
1932         target_freq = clamp_val(target_freq, policy->min, policy->max);
1933
1934         return cpufreq_driver->fast_switch(policy, target_freq);
1935 }
1936 EXPORT_SYMBOL_GPL(cpufreq_driver_fast_switch);
1937
1938 /* Must set freqs->new to intermediate frequency */
1939 static int __target_intermediate(struct cpufreq_policy *policy,
1940                                  struct cpufreq_freqs *freqs, int index)
1941 {
1942         int ret;
1943
1944         freqs->new = cpufreq_driver->get_intermediate(policy, index);
1945
1946         /* We don't need to switch to intermediate freq */
1947         if (!freqs->new)
1948                 return 0;
1949
1950         pr_debug("%s: cpu: %d, switching to intermediate freq: oldfreq: %u, intermediate freq: %u\n",
1951                  __func__, policy->cpu, freqs->old, freqs->new);
1952
1953         cpufreq_freq_transition_begin(policy, freqs);
1954         ret = cpufreq_driver->target_intermediate(policy, index);
1955         cpufreq_freq_transition_end(policy, freqs, ret);
1956
1957         if (ret)
1958                 pr_err("%s: Failed to change to intermediate frequency: %d\n",
1959                        __func__, ret);
1960
1961         return ret;
1962 }
1963
1964 static int __target_index(struct cpufreq_policy *policy, int index)
1965 {
1966         struct cpufreq_freqs freqs = {.old = policy->cur, .flags = 0};
1967         unsigned int intermediate_freq = 0;
1968         unsigned int newfreq = policy->freq_table[index].frequency;
1969         int retval = -EINVAL;
1970         bool notify;
1971
1972         if (newfreq == policy->cur)
1973                 return 0;
1974
1975         notify = !(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION);
1976         if (notify) {
1977                 /* Handle switching to intermediate frequency */
1978                 if (cpufreq_driver->get_intermediate) {
1979                         retval = __target_intermediate(policy, &freqs, index);
1980                         if (retval)
1981                                 return retval;
1982
1983                         intermediate_freq = freqs.new;
1984                         /* Set old freq to intermediate */
1985                         if (intermediate_freq)
1986                                 freqs.old = freqs.new;
1987                 }
1988
1989                 freqs.new = newfreq;
1990                 pr_debug("%s: cpu: %d, oldfreq: %u, new freq: %u\n",
1991                          __func__, policy->cpu, freqs.old, freqs.new);
1992
1993                 cpufreq_freq_transition_begin(policy, &freqs);
1994         }
1995
1996         retval = cpufreq_driver->target_index(policy, index);
1997         if (retval)
1998                 pr_err("%s: Failed to change cpu frequency: %d\n", __func__,
1999                        retval);
2000
2001         if (notify) {
2002                 cpufreq_freq_transition_end(policy, &freqs, retval);
2003
2004                 /*
2005                  * Failed after setting to intermediate freq? Driver should have
2006                  * reverted back to initial frequency and so should we. Check
2007                  * here for intermediate_freq instead of get_intermediate, in
2008                  * case we haven't switched to intermediate freq at all.
2009                  */
2010                 if (unlikely(retval && intermediate_freq)) {
2011                         freqs.old = intermediate_freq;
2012                         freqs.new = policy->restore_freq;
2013                         cpufreq_freq_transition_begin(policy, &freqs);
2014                         cpufreq_freq_transition_end(policy, &freqs, 0);
2015                 }
2016         }
2017
2018         return retval;
2019 }
2020
2021 int __cpufreq_driver_target(struct cpufreq_policy *policy,
2022                             unsigned int target_freq,
2023                             unsigned int relation)
2024 {
2025         unsigned int old_target_freq = target_freq;
2026         int index;
2027
2028         if (cpufreq_disabled())
2029                 return -ENODEV;
2030
2031         /* Make sure that target_freq is within supported range */
2032         target_freq = clamp_val(target_freq, policy->min, policy->max);
2033
2034         pr_debug("target for CPU %u: %u kHz, relation %u, requested %u kHz\n",
2035                  policy->cpu, target_freq, relation, old_target_freq);
2036
2037         /*
2038          * This might look like a redundant call as we are checking it again
2039          * after finding index. But it is left intentionally for cases where
2040          * exactly same freq is called again and so we can save on few function
2041          * calls.
2042          */
2043         if (target_freq == policy->cur)
2044                 return 0;
2045
2046         /* Save last value to restore later on errors */
2047         policy->restore_freq = policy->cur;
2048
2049         if (cpufreq_driver->target)
2050                 return cpufreq_driver->target(policy, target_freq, relation);
2051
2052         if (!cpufreq_driver->target_index)
2053                 return -EINVAL;
2054
2055         index = cpufreq_frequency_table_target(policy, target_freq, relation);
2056
2057         return __target_index(policy, index);
2058 }
2059 EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
2060
2061 int cpufreq_driver_target(struct cpufreq_policy *policy,
2062                           unsigned int target_freq,
2063                           unsigned int relation)
2064 {
2065         int ret = -EINVAL;
2066
2067         down_write(&policy->rwsem);
2068
2069         ret = __cpufreq_driver_target(policy, target_freq, relation);
2070
2071         up_write(&policy->rwsem);
2072
2073         return ret;
2074 }
2075 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
2076
2077 __weak struct cpufreq_governor *cpufreq_fallback_governor(void)
2078 {
2079         return NULL;
2080 }
2081
2082 static int cpufreq_init_governor(struct cpufreq_policy *policy)
2083 {
2084         int ret;
2085
2086         /* Don't start any governor operations if we are entering suspend */
2087         if (cpufreq_suspended)
2088                 return 0;
2089         /*
2090          * Governor might not be initiated here if ACPI _PPC changed
2091          * notification happened, so check it.
2092          */
2093         if (!policy->governor)
2094                 return -EINVAL;
2095
2096         /* Platform doesn't want dynamic frequency switching ? */
2097         if (policy->governor->dynamic_switching &&
2098             cpufreq_driver->flags & CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING) {
2099                 struct cpufreq_governor *gov = cpufreq_fallback_governor();
2100
2101                 if (gov) {
2102                         pr_warn("Can't use %s governor as dynamic switching is disallowed. Fallback to %s governor\n",
2103                                 policy->governor->name, gov->name);
2104                         policy->governor = gov;
2105                 } else {
2106                         return -EINVAL;
2107                 }
2108         }
2109
2110         if (!try_module_get(policy->governor->owner))
2111                 return -EINVAL;
2112
2113         pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
2114
2115         if (policy->governor->init) {
2116                 ret = policy->governor->init(policy);
2117                 if (ret) {
2118                         module_put(policy->governor->owner);
2119                         return ret;
2120                 }
2121         }
2122
2123         return 0;
2124 }
2125
2126 static void cpufreq_exit_governor(struct cpufreq_policy *policy)
2127 {
2128         if (cpufreq_suspended || !policy->governor)
2129                 return;
2130
2131         pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
2132
2133         if (policy->governor->exit)
2134                 policy->governor->exit(policy);
2135
2136         module_put(policy->governor->owner);
2137 }
2138
2139 static int cpufreq_start_governor(struct cpufreq_policy *policy)
2140 {
2141         int ret;
2142
2143         if (cpufreq_suspended)
2144                 return 0;
2145
2146         if (!policy->governor)
2147                 return -EINVAL;
2148
2149         pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
2150
2151         if (cpufreq_driver->get)
2152                 cpufreq_update_current_freq(policy);
2153
2154         if (policy->governor->start) {
2155                 ret = policy->governor->start(policy);
2156                 if (ret)
2157                         return ret;
2158         }
2159
2160         if (policy->governor->limits)
2161                 policy->governor->limits(policy);
2162
2163         return 0;
2164 }
2165
2166 static void cpufreq_stop_governor(struct cpufreq_policy *policy)
2167 {
2168         if (cpufreq_suspended || !policy->governor)
2169                 return;
2170
2171         pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
2172
2173         if (policy->governor->stop)
2174                 policy->governor->stop(policy);
2175 }
2176
2177 static void cpufreq_governor_limits(struct cpufreq_policy *policy)
2178 {
2179         if (cpufreq_suspended || !policy->governor)
2180                 return;
2181
2182         pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
2183
2184         if (policy->governor->limits)
2185                 policy->governor->limits(policy);
2186 }
2187
2188 int cpufreq_register_governor(struct cpufreq_governor *governor)
2189 {
2190         int err;
2191
2192         if (!governor)
2193                 return -EINVAL;
2194
2195         if (cpufreq_disabled())
2196                 return -ENODEV;
2197
2198         mutex_lock(&cpufreq_governor_mutex);
2199
2200         err = -EBUSY;
2201         if (!find_governor(governor->name)) {
2202                 err = 0;
2203                 list_add(&governor->governor_list, &cpufreq_governor_list);
2204         }
2205
2206         mutex_unlock(&cpufreq_governor_mutex);
2207         return err;
2208 }
2209 EXPORT_SYMBOL_GPL(cpufreq_register_governor);
2210
2211 void cpufreq_unregister_governor(struct cpufreq_governor *governor)
2212 {
2213         struct cpufreq_policy *policy;
2214         unsigned long flags;
2215
2216         if (!governor)
2217                 return;
2218
2219         if (cpufreq_disabled())
2220                 return;
2221
2222         /* clear last_governor for all inactive policies */
2223         read_lock_irqsave(&cpufreq_driver_lock, flags);
2224         for_each_inactive_policy(policy) {
2225                 if (!strcmp(policy->last_governor, governor->name)) {
2226                         policy->governor = NULL;
2227                         strcpy(policy->last_governor, "\0");
2228                 }
2229         }
2230         read_unlock_irqrestore(&cpufreq_driver_lock, flags);
2231
2232         mutex_lock(&cpufreq_governor_mutex);
2233         list_del(&governor->governor_list);
2234         mutex_unlock(&cpufreq_governor_mutex);
2235 }
2236 EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
2237
2238
2239 /*********************************************************************
2240  *                          POLICY INTERFACE                         *
2241  *********************************************************************/
2242
2243 /**
2244  * cpufreq_get_policy - get the current cpufreq_policy
2245  * @policy: struct cpufreq_policy into which the current cpufreq_policy
2246  *      is written
2247  *
2248  * Reads the current cpufreq policy.
2249  */
2250 int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
2251 {
2252         struct cpufreq_policy *cpu_policy;
2253         if (!policy)
2254                 return -EINVAL;
2255
2256         cpu_policy = cpufreq_cpu_get(cpu);
2257         if (!cpu_policy)
2258                 return -EINVAL;
2259
2260         memcpy(policy, cpu_policy, sizeof(*policy));
2261
2262         cpufreq_cpu_put(cpu_policy);
2263         return 0;
2264 }
2265 EXPORT_SYMBOL(cpufreq_get_policy);
2266
2267 /**
2268  * cpufreq_set_policy - Modify cpufreq policy parameters.
2269  * @policy: Policy object to modify.
2270  * @new_policy: New policy data.
2271  *
2272  * Pass @new_policy to the cpufreq driver's ->verify() callback, run the
2273  * installed policy notifiers for it with the CPUFREQ_ADJUST value, pass it to
2274  * the driver's ->verify() callback again and run the notifiers for it again
2275  * with the CPUFREQ_NOTIFY value.  Next, copy the min and max parameters
2276  * of @new_policy to @policy and either invoke the driver's ->setpolicy()
2277  * callback (if present) or carry out a governor update for @policy.  That is,
2278  * run the current governor's ->limits() callback (if the governor field in
2279  * @new_policy points to the same object as the one in @policy) or replace the
2280  * governor for @policy with the new one stored in @new_policy.
2281  *
2282  * The cpuinfo part of @policy is not updated by this function.
2283  */
2284 int cpufreq_set_policy(struct cpufreq_policy *policy,
2285                        struct cpufreq_policy *new_policy)
2286 {
2287         struct cpufreq_governor *old_gov;
2288         int ret;
2289
2290         pr_debug("setting new policy for CPU %u: %u - %u kHz\n",
2291                  new_policy->cpu, new_policy->min, new_policy->max);
2292
2293         memcpy(&new_policy->cpuinfo, &policy->cpuinfo, sizeof(policy->cpuinfo));
2294
2295         /*
2296         * This check works well when we store new min/max freq attributes,
2297         * because new_policy is a copy of policy with one field updated.
2298         */
2299         if (new_policy->min > new_policy->max)
2300                 return -EINVAL;
2301
2302         /* verify the cpu speed can be set within this limit */
2303         ret = cpufreq_driver->verify(new_policy);
2304         if (ret)
2305                 return ret;
2306
2307         /* adjust if necessary - all reasons */
2308         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
2309                         CPUFREQ_ADJUST, new_policy);
2310
2311         /*
2312          * verify the cpu speed can be set within this limit, which might be
2313          * different to the first one
2314          */
2315         ret = cpufreq_driver->verify(new_policy);
2316         if (ret)
2317                 return ret;
2318
2319         /* notification of the new policy */
2320         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
2321                         CPUFREQ_NOTIFY, new_policy);
2322
2323         policy->min = new_policy->min;
2324         policy->max = new_policy->max;
2325         trace_cpu_frequency_limits(policy);
2326
2327         policy->cached_target_freq = UINT_MAX;
2328
2329         pr_debug("new min and max freqs are %u - %u kHz\n",
2330                  policy->min, policy->max);
2331
2332         if (cpufreq_driver->setpolicy) {
2333                 policy->policy = new_policy->policy;
2334                 pr_debug("setting range\n");
2335                 return cpufreq_driver->setpolicy(policy);
2336         }
2337
2338         if (new_policy->governor == policy->governor) {
2339                 pr_debug("governor limits update\n");
2340                 cpufreq_governor_limits(policy);
2341                 return 0;
2342         }
2343
2344         pr_debug("governor switch\n");
2345
2346         /* save old, working values */
2347         old_gov = policy->governor;
2348         /* end old governor */
2349         if (old_gov) {
2350                 cpufreq_stop_governor(policy);
2351                 cpufreq_exit_governor(policy);
2352         }
2353
2354         /* start new governor */
2355         policy->governor = new_policy->governor;
2356         ret = cpufreq_init_governor(policy);
2357         if (!ret) {
2358                 ret = cpufreq_start_governor(policy);
2359                 if (!ret) {
2360                         pr_debug("governor change\n");
2361                         sched_cpufreq_governor_change(policy, old_gov);
2362                         return 0;
2363                 }
2364                 cpufreq_exit_governor(policy);
2365         }
2366
2367         /* new governor failed, so re-start old one */
2368         pr_debug("starting governor %s failed\n", policy->governor->name);
2369         if (old_gov) {
2370                 policy->governor = old_gov;
2371                 if (cpufreq_init_governor(policy))
2372                         policy->governor = NULL;
2373                 else
2374                         cpufreq_start_governor(policy);
2375         }
2376
2377         return ret;
2378 }
2379
2380 /**
2381  * cpufreq_update_policy - Re-evaluate an existing cpufreq policy.
2382  * @cpu: CPU to re-evaluate the policy for.
2383  *
2384  * Update the current frequency for the cpufreq policy of @cpu and use
2385  * cpufreq_set_policy() to re-apply the min and max limits saved in the
2386  * user_policy sub-structure of that policy, which triggers the evaluation
2387  * of policy notifiers and the cpufreq driver's ->verify() callback for the
2388  * policy in question, among other things.
2389  */
2390 void cpufreq_update_policy(unsigned int cpu)
2391 {
2392         struct cpufreq_policy *policy = cpufreq_cpu_acquire(cpu);
2393         struct cpufreq_policy new_policy;
2394
2395         if (!policy)
2396                 return;
2397
2398         /*
2399          * BIOS might change freq behind our back
2400          * -> ask driver for current freq and notify governors about a change
2401          */
2402         if (cpufreq_driver->get && has_target() &&
2403             (cpufreq_suspended || WARN_ON(!cpufreq_update_current_freq(policy))))
2404                 goto unlock;
2405
2406         pr_debug("updating policy for CPU %u\n", cpu);
2407         memcpy(&new_policy, policy, sizeof(*policy));
2408         new_policy.min = policy->user_policy.min;
2409         new_policy.max = policy->user_policy.max;
2410
2411         cpufreq_set_policy(policy, &new_policy);
2412
2413 unlock:
2414         cpufreq_cpu_release(policy);
2415 }
2416 EXPORT_SYMBOL(cpufreq_update_policy);
2417
2418 /**
2419  * cpufreq_update_limits - Update policy limits for a given CPU.
2420  * @cpu: CPU to update the policy limits for.
2421  *
2422  * Invoke the driver's ->update_limits callback if present or call
2423  * cpufreq_update_policy() for @cpu.
2424  */
2425 void cpufreq_update_limits(unsigned int cpu)
2426 {
2427         if (cpufreq_driver->update_limits)
2428                 cpufreq_driver->update_limits(cpu);
2429         else
2430                 cpufreq_update_policy(cpu);
2431 }
2432 EXPORT_SYMBOL_GPL(cpufreq_update_limits);
2433
2434 /*********************************************************************
2435  *               BOOST                                               *
2436  *********************************************************************/
2437 static int cpufreq_boost_set_sw(int state)
2438 {
2439         struct cpufreq_policy *policy;
2440         int ret = -EINVAL;
2441
2442         for_each_active_policy(policy) {
2443                 if (!policy->freq_table)
2444                         continue;
2445
2446                 ret = cpufreq_frequency_table_cpuinfo(policy,
2447                                                       policy->freq_table);
2448                 if (ret) {
2449                         pr_err("%s: Policy frequency update failed\n",
2450                                __func__);
2451                         break;
2452                 }
2453
2454                 down_write(&policy->rwsem);
2455                 policy->user_policy.max = policy->max;
2456                 cpufreq_governor_limits(policy);
2457                 up_write(&policy->rwsem);
2458         }
2459
2460         return ret;
2461 }
2462
2463 int cpufreq_boost_trigger_state(int state)
2464 {
2465         unsigned long flags;
2466         int ret = 0;
2467
2468         if (cpufreq_driver->boost_enabled == state)
2469                 return 0;
2470
2471         write_lock_irqsave(&cpufreq_driver_lock, flags);
2472         cpufreq_driver->boost_enabled = state;
2473         write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2474
2475         ret = cpufreq_driver->set_boost(state);
2476         if (ret) {
2477                 write_lock_irqsave(&cpufreq_driver_lock, flags);
2478                 cpufreq_driver->boost_enabled = !state;
2479                 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2480
2481                 pr_err("%s: Cannot %s BOOST\n",
2482                        __func__, state ? "enable" : "disable");
2483         }
2484
2485         return ret;
2486 }
2487
2488 static bool cpufreq_boost_supported(void)
2489 {
2490         return cpufreq_driver->set_boost;
2491 }
2492
2493 static int create_boost_sysfs_file(void)
2494 {
2495         int ret;
2496
2497         ret = sysfs_create_file(cpufreq_global_kobject, &boost.attr);
2498         if (ret)
2499                 pr_err("%s: cannot register global BOOST sysfs file\n",
2500                        __func__);
2501
2502         return ret;
2503 }
2504
2505 static void remove_boost_sysfs_file(void)
2506 {
2507         if (cpufreq_boost_supported())
2508                 sysfs_remove_file(cpufreq_global_kobject, &boost.attr);
2509 }
2510
2511 int cpufreq_enable_boost_support(void)
2512 {
2513         if (!cpufreq_driver)
2514                 return -EINVAL;
2515
2516         if (cpufreq_boost_supported())
2517                 return 0;
2518
2519         cpufreq_driver->set_boost = cpufreq_boost_set_sw;
2520
2521         /* This will get removed on driver unregister */
2522         return create_boost_sysfs_file();
2523 }
2524 EXPORT_SYMBOL_GPL(cpufreq_enable_boost_support);
2525
2526 int cpufreq_boost_enabled(void)
2527 {
2528         return cpufreq_driver->boost_enabled;
2529 }
2530 EXPORT_SYMBOL_GPL(cpufreq_boost_enabled);
2531
2532 /*********************************************************************
2533  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
2534  *********************************************************************/
2535 static enum cpuhp_state hp_online;
2536
2537 static int cpuhp_cpufreq_online(unsigned int cpu)
2538 {
2539         cpufreq_online(cpu);
2540
2541         return 0;
2542 }
2543
2544 static int cpuhp_cpufreq_offline(unsigned int cpu)
2545 {
2546         cpufreq_offline(cpu);
2547
2548         return 0;
2549 }
2550
2551 /**
2552  * cpufreq_register_driver - register a CPU Frequency driver
2553  * @driver_data: A struct cpufreq_driver containing the values#
2554  * submitted by the CPU Frequency driver.
2555  *
2556  * Registers a CPU Frequency driver to this core code. This code
2557  * returns zero on success, -EEXIST when another driver got here first
2558  * (and isn't unregistered in the meantime).
2559  *
2560  */
2561 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
2562 {
2563         unsigned long flags;
2564         int ret;
2565
2566         if (cpufreq_disabled())
2567                 return -ENODEV;
2568
2569         if (!driver_data || !driver_data->verify || !driver_data->init ||
2570             !(driver_data->setpolicy || driver_data->target_index ||
2571                     driver_data->target) ||
2572              (driver_data->setpolicy && (driver_data->target_index ||
2573                     driver_data->target)) ||
2574              (!driver_data->get_intermediate != !driver_data->target_intermediate) ||
2575              (!driver_data->online != !driver_data->offline))
2576                 return -EINVAL;
2577
2578         pr_debug("trying to register driver %s\n", driver_data->name);
2579
2580         /* Protect against concurrent CPU online/offline. */
2581         cpus_read_lock();
2582
2583         write_lock_irqsave(&cpufreq_driver_lock, flags);
2584         if (cpufreq_driver) {
2585                 write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2586                 ret = -EEXIST;
2587                 goto out;
2588         }
2589         cpufreq_driver = driver_data;
2590         write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2591
2592         if (driver_data->setpolicy)
2593                 driver_data->flags |= CPUFREQ_CONST_LOOPS;
2594
2595         if (cpufreq_boost_supported()) {
2596                 ret = create_boost_sysfs_file();
2597                 if (ret)
2598                         goto err_null_driver;
2599         }
2600
2601         ret = subsys_interface_register(&cpufreq_interface);
2602         if (ret)
2603                 goto err_boost_unreg;
2604
2605         if (!(cpufreq_driver->flags & CPUFREQ_STICKY) &&
2606             list_empty(&cpufreq_policy_list)) {
2607                 /* if all ->init() calls failed, unregister */
2608                 ret = -ENODEV;
2609                 pr_debug("%s: No CPU initialized for driver %s\n", __func__,
2610                          driver_data->name);
2611                 goto err_if_unreg;
2612         }
2613
2614         ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
2615                                                    "cpufreq:online",
2616                                                    cpuhp_cpufreq_online,
2617                                                    cpuhp_cpufreq_offline);
2618         if (ret < 0)
2619                 goto err_if_unreg;
2620         hp_online = ret;
2621         ret = 0;
2622
2623         pr_debug("driver %s up and running\n", driver_data->name);
2624         goto out;
2625
2626 err_if_unreg:
2627         subsys_interface_unregister(&cpufreq_interface);
2628 err_boost_unreg:
2629         remove_boost_sysfs_file();
2630 err_null_driver:
2631         write_lock_irqsave(&cpufreq_driver_lock, flags);
2632         cpufreq_driver = NULL;
2633         write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2634 out:
2635         cpus_read_unlock();
2636         return ret;
2637 }
2638 EXPORT_SYMBOL_GPL(cpufreq_register_driver);
2639
2640 /**
2641  * cpufreq_unregister_driver - unregister the current CPUFreq driver
2642  *
2643  * Unregister the current CPUFreq driver. Only call this if you have
2644  * the right to do so, i.e. if you have succeeded in initialising before!
2645  * Returns zero if successful, and -EINVAL if the cpufreq_driver is
2646  * currently not initialised.
2647  */
2648 int cpufreq_unregister_driver(struct cpufreq_driver *driver)
2649 {
2650         unsigned long flags;
2651
2652         if (!cpufreq_driver || (driver != cpufreq_driver))
2653                 return -EINVAL;
2654
2655         pr_debug("unregistering driver %s\n", driver->name);
2656
2657         /* Protect against concurrent cpu hotplug */
2658         cpus_read_lock();
2659         subsys_interface_unregister(&cpufreq_interface);
2660         remove_boost_sysfs_file();
2661         cpuhp_remove_state_nocalls_cpuslocked(hp_online);
2662
2663         write_lock_irqsave(&cpufreq_driver_lock, flags);
2664
2665         cpufreq_driver = NULL;
2666
2667         write_unlock_irqrestore(&cpufreq_driver_lock, flags);
2668         cpus_read_unlock();
2669
2670         return 0;
2671 }
2672 EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
2673
2674 /*
2675  * Stop cpufreq at shutdown to make sure it isn't holding any locks
2676  * or mutexes when secondary CPUs are halted.
2677  */
2678 static struct syscore_ops cpufreq_syscore_ops = {
2679         .shutdown = cpufreq_suspend,
2680 };
2681
2682 struct kobject *cpufreq_global_kobject;
2683 EXPORT_SYMBOL(cpufreq_global_kobject);
2684
2685 static int __init cpufreq_core_init(void)
2686 {
2687         if (cpufreq_disabled())
2688                 return -ENODEV;
2689
2690         cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj);
2691         BUG_ON(!cpufreq_global_kobject);
2692
2693         register_syscore_ops(&cpufreq_syscore_ops);
2694
2695         return 0;
2696 }
2697 module_param(off, int, 0444);
2698 core_initcall(cpufreq_core_init);