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  *
   7  *  Oct 2005 - Ashok Raj <ashok.raj@intel.com>
   8  *      Added handling for CPU hotplug
   9  *  Feb 2006 - Jacob Shin <jacob.shin@amd.com>
  10  *      Fix handling for CPU hotplug -- affected CPUs
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2 as
  14  * published by the Free Software Foundation.
  15  *
  16  */
  17
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/notifier.h>
  22 #include <linux/cpufreq.h>
  23 #include <linux/delay.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/spinlock.h>
  26 #include <linux/device.h>
  27 #include <linux/slab.h>
  28 #include <linux/cpu.h>
  29 #include <linux/completion.h>
  30 #include <linux/mutex.h>
  31
  32 #include <trace/events/power.h>
  33
  34 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_CORE, \
  35                                                 "cpufreq-core", msg)
  36
  37 /**
  38  * The "cpufreq driver" - the arch- or hardware-dependent low
  39  * level driver of CPUFreq support, and its spinlock. This lock
  40  * also protects the cpufreq_cpu_data array.
  41  */
  42 static struct cpufreq_driver *cpufreq_driver;
  43 static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
  44 #ifdef CONFIG_HOTPLUG_CPU
  45 /* This one keeps track of the previously set governor of a removed CPU */
  46 static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
  47 #endif
  48 static DEFINE_SPINLOCK(cpufreq_driver_lock);
  49
  50 /*
  51  * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
  52  * all cpufreq/hotplug/workqueue/etc related lock issues.
  53  *
  54  * The rules for this semaphore:
  55  * - Any routine that wants to read from the policy structure will
  56  *   do a down_read on this semaphore.
  57  * - Any routine that will write to the policy structure and/or may take away
  58  *   the policy altogether (eg. CPU hotplug), will hold this lock in write
  59  *   mode before doing so.
  60  *
  61  * Additional rules:
  62  * - All holders of the lock should check to make sure that the CPU they
  63  *   are concerned with are online after they get the lock.
  64  * - Governor routines that can be called in cpufreq hotplug path should not
  65  *   take this sem as top level hotplug notifier handler takes this.
  66  * - Lock should not be held across
  67  *     __cpufreq_governor(data, CPUFREQ_GOV_STOP);
  68  */
  69 static DEFINE_PER_CPU(int, cpufreq_policy_cpu);
  70 static DEFINE_PER_CPU(struct rw_semaphore, cpu_policy_rwsem);
  71
  72 #define lock_policy_rwsem(mode, cpu)                                    \
  73 static int lock_policy_rwsem_##mode                                     \
  74 (int cpu)                                                               \
  75 {                                                                       \
  76         int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);              \
  77         BUG_ON(policy_cpu == -1);                                       \
  78         down_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu));            \
  79         if (unlikely(!cpu_online(cpu))) {                               \
  80                 up_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu));      \
  81                 return -1;                                              \
  82         }                                                               \
  83                                                                         \
  84         return 0;                                                       \
  85 }
  86
  87 lock_policy_rwsem(read, cpu);
  88
  89 lock_policy_rwsem(write, cpu);
  90
  91 static void unlock_policy_rwsem_read(int cpu)
  92 {
  93         int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);
  94         BUG_ON(policy_cpu == -1);
  95         up_read(&per_cpu(cpu_policy_rwsem, policy_cpu));
  96 }
  97
  98 static void unlock_policy_rwsem_write(int cpu)
  99 {
 100         int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);
 101         BUG_ON(policy_cpu == -1);
 102         up_write(&per_cpu(cpu_policy_rwsem, policy_cpu));
 103 }
 104
 105
 106 /* internal prototypes */
 107 static int __cpufreq_governor(struct cpufreq_policy *policy,
 108                 unsigned int event);
 109 static unsigned int __cpufreq_get(unsigned int cpu);
 110 static void handle_update(struct work_struct *work);
 111
 112 /**
 113  * Two notifier lists: the "policy" list is involved in the
 114  * validation process for a new CPU frequency policy; the
 115  * "transition" list for kernel code that needs to handle
 116  * changes to devices when the CPU clock speed changes.
 117  * The mutex locks both lists.
 118  */
 119 static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
 120 static struct srcu_notifier_head cpufreq_transition_notifier_list;
 121
 122 static bool init_cpufreq_transition_notifier_list_called;
 123 static int __init init_cpufreq_transition_notifier_list(void)
 124 {
 125         srcu_init_notifier_head(&cpufreq_transition_notifier_list);
 126         init_cpufreq_transition_notifier_list_called = true;
 127         return 0;
 128 }
 129 pure_initcall(init_cpufreq_transition_notifier_list);
 130
 131 static LIST_HEAD(cpufreq_governor_list);
 132 static DEFINE_MUTEX(cpufreq_governor_mutex);
 133
 134 struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
 135 {
 136         struct cpufreq_policy *data;
 137         unsigned long flags;
 138
 139         if (cpu >= nr_cpu_ids)
 140                 goto err_out;
 141
 142         /* get the cpufreq driver */
 143         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 144
 145         if (!cpufreq_driver)
 146                 goto err_out_unlock;
 147
 148         if (!try_module_get(cpufreq_driver->owner))
 149                 goto err_out_unlock;
 150
 151
 152         /* get the CPU */
 153         data = per_cpu(cpufreq_cpu_data, cpu);
 154
 155         if (!data)
 156                 goto err_out_put_module;
 157
 158         if (!kobject_get(&data->kobj))
 159                 goto err_out_put_module;
 160
 161         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 162         return data;
 163
 164 err_out_put_module:
 165         module_put(cpufreq_driver->owner);
 166 err_out_unlock:
 167         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 168 err_out:
 169         return NULL;
 170 }
 171 EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
 172
 173
 174 void cpufreq_cpu_put(struct cpufreq_policy *data)
 175 {
 176         kobject_put(&data->kobj);
 177         module_put(cpufreq_driver->owner);
 178 }
 179 EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
 180
 181
 182 /*********************************************************************
 183  *                     UNIFIED DEBUG HELPERS                         *
 184  *********************************************************************/
 185 #ifdef CONFIG_CPU_FREQ_DEBUG
 186
 187 /* what part(s) of the CPUfreq subsystem are debugged? */
 188 static unsigned int debug;
 189
 190 /* is the debug output ratelimit'ed using printk_ratelimit? User can
 191  * set or modify this value.
 192  */
 193 static unsigned int debug_ratelimit = 1;
 194
 195 /* is the printk_ratelimit'ing enabled? It's enabled after a successful
 196  * loading of a cpufreq driver, temporarily disabled when a new policy
 197  * is set, and disabled upon cpufreq driver removal
 198  */
 199 static unsigned int disable_ratelimit = 1;
 200 static DEFINE_SPINLOCK(disable_ratelimit_lock);
 201
 202 static void cpufreq_debug_enable_ratelimit(void)
 203 {
 204         unsigned long flags;
 205
 206         spin_lock_irqsave(&disable_ratelimit_lock, flags);
 207         if (disable_ratelimit)
 208                 disable_ratelimit--;
 209         spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
 210 }
 211
 212 static void cpufreq_debug_disable_ratelimit(void)
 213 {
 214         unsigned long flags;
 215
 216         spin_lock_irqsave(&disable_ratelimit_lock, flags);
 217         disable_ratelimit++;
 218         spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
 219 }
 220
 221 void cpufreq_debug_printk(unsigned int type, const char *prefix,
 222                         const char *fmt, ...)
 223 {
 224         char s[256];
 225         va_list args;
 226         unsigned int len;
 227         unsigned long flags;
 228
 229         WARN_ON(!prefix);
 230         if (type & debug) {
 231                 spin_lock_irqsave(&disable_ratelimit_lock, flags);
 232                 if (!disable_ratelimit && debug_ratelimit
 233                                         && !printk_ratelimit()) {
 234                         spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
 235                         return;
 236                 }
 237                 spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
 238
 239                 len = snprintf(s, 256, KERN_DEBUG "%s: ", prefix);
 240
 241                 va_start(args, fmt);
 242                 len += vsnprintf(&s[len], (256 - len), fmt, args);
 243                 va_end(args);
 244
 245                 printk(s);
 246
 247                 WARN_ON(len < 5);
 248         }
 249 }
 250 EXPORT_SYMBOL(cpufreq_debug_printk);
 251
 252
 253 module_param(debug, uint, 0644);
 254 MODULE_PARM_DESC(debug, "CPUfreq debugging: add 1 to debug core,"
 255                         " 2 to debug drivers, and 4 to debug governors.");
 256
 257 module_param(debug_ratelimit, uint, 0644);
 258 MODULE_PARM_DESC(debug_ratelimit, "CPUfreq debugging:"
 259                                         " set to 0 to disable ratelimiting.");
 260
 261 #else /* !CONFIG_CPU_FREQ_DEBUG */
 262
 263 static inline void cpufreq_debug_enable_ratelimit(void) { return; }
 264 static inline void cpufreq_debug_disable_ratelimit(void) { return; }
 265
 266 #endif /* CONFIG_CPU_FREQ_DEBUG */
 267
 268
 269 /*********************************************************************
 270  *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
 271  *********************************************************************/
 272
 273 /**
 274  * adjust_jiffies - adjust the system "loops_per_jiffy"
 275  *
 276  * This function alters the system "loops_per_jiffy" for the clock
 277  * speed change. Note that loops_per_jiffy cannot be updated on SMP
 278  * systems as each CPU might be scaled differently. So, use the arch
 279  * per-CPU loops_per_jiffy value wherever possible.
 280  */
 281 #ifndef CONFIG_SMP
 282 static unsigned long l_p_j_ref;
 283 static unsigned int  l_p_j_ref_freq;
 284
 285 static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 286 {
 287         if (ci->flags & CPUFREQ_CONST_LOOPS)
 288                 return;
 289
 290         if (!l_p_j_ref_freq) {
 291                 l_p_j_ref = loops_per_jiffy;
 292                 l_p_j_ref_freq = ci->old;
 293                 dprintk("saving %lu as reference value for loops_per_jiffy; "
 294                         "freq is %u kHz\n", l_p_j_ref, l_p_j_ref_freq);
 295         }
 296         if ((val == CPUFREQ_PRECHANGE  && ci->old < ci->new) ||
 297             (val == CPUFREQ_POSTCHANGE && ci->old > ci->new) ||
 298             (val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE)) {
 299                 loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq,
 300                                                                 ci->new);
 301                 dprintk("scaling loops_per_jiffy to %lu "
 302                         "for frequency %u kHz\n", loops_per_jiffy, ci->new);
 303         }
 304 }
 305 #else
 306 static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 307 {
 308         return;
 309 }
 310 #endif
 311
 312
 313 /**
 314  * cpufreq_notify_transition - call notifier chain and adjust_jiffies
 315  * on frequency transition.
 316  *
 317  * This function calls the transition notifiers and the "adjust_jiffies"
 318  * function. It is called twice on all CPU frequency changes that have
 319  * external effects.
 320  */
 321 void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
 322 {
 323         struct cpufreq_policy *policy;
 324
 325         BUG_ON(irqs_disabled());
 326
 327         freqs->flags = cpufreq_driver->flags;
 328         dprintk("notification %u of frequency transition to %u kHz\n",
 329                 state, freqs->new);
 330
 331         policy = per_cpu(cpufreq_cpu_data, freqs->cpu);
 332         switch (state) {
 333
 334         case CPUFREQ_PRECHANGE:
 335                 /* detect if the driver reported a value as "old frequency"
 336                  * which is not equal to what the cpufreq core thinks is
 337                  * "old frequency".
 338                  */
 339                 if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
 340                         if ((policy) && (policy->cpu == freqs->cpu) &&
 341                             (policy->cur) && (policy->cur != freqs->old)) {
 342                                 dprintk("Warning: CPU frequency is"
 343                                         " %u, cpufreq assumed %u kHz.\n",
 344                                         freqs->old, policy->cur);
 345                                 freqs->old = policy->cur;
 346                         }
 347                 }
 348                 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
 349                                 CPUFREQ_PRECHANGE, freqs);
 350                 adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
 351                 break;
 352
 353         case CPUFREQ_POSTCHANGE:
 354                 adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
 355                 dprintk("FREQ: %lu - CPU: %lu", (unsigned long)freqs->new,
 356                         (unsigned long)freqs->cpu);
 357                 trace_power_frequency(POWER_PSTATE, freqs->new, freqs->cpu);
 358                 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
 359                                 CPUFREQ_POSTCHANGE, freqs);
 360                 if (likely(policy) && likely(policy->cpu == freqs->cpu))
 361                         policy->cur = freqs->new;
 362                 break;
 363         }
 364 }
 365 EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
 366
 367
 368
 369 /*********************************************************************
 370  *                          SYSFS INTERFACE                          *
 371  *********************************************************************/
 372
 373 static struct cpufreq_governor *__find_governor(const char *str_governor)
 374 {
 375         struct cpufreq_governor *t;
 376
 377         list_for_each_entry(t, &cpufreq_governor_list, governor_list)
 378                 if (!strnicmp(str_governor, t->name, CPUFREQ_NAME_LEN))
 379                         return t;
 380
 381         return NULL;
 382 }
 383
 384 /**
 385  * cpufreq_parse_governor - parse a governor string
 386  */
 387 static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
 388                                 struct cpufreq_governor **governor)
 389 {
 390         int err = -EINVAL;
 391
 392         if (!cpufreq_driver)
 393                 goto out;
 394
 395         if (cpufreq_driver->setpolicy) {
 396                 if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
 397                         *policy = CPUFREQ_POLICY_PERFORMANCE;
 398                         err = 0;
 399                 } else if (!strnicmp(str_governor, "powersave",
 400                                                 CPUFREQ_NAME_LEN)) {
 401                         *policy = CPUFREQ_POLICY_POWERSAVE;
 402                         err = 0;
 403                 }
 404         } else if (cpufreq_driver->target) {
 405                 struct cpufreq_governor *t;
 406
 407                 mutex_lock(&cpufreq_governor_mutex);
 408
 409                 t = __find_governor(str_governor);
 410
 411                 if (t == NULL) {
 412                         char *name = kasprintf(GFP_KERNEL, "cpufreq_%s",
 413                                                                 str_governor);
 414
 415                         if (name) {
 416                                 int ret;
 417
 418                                 mutex_unlock(&cpufreq_governor_mutex);
 419                                 ret = request_module("%s", name);
 420                                 mutex_lock(&cpufreq_governor_mutex);
 421
 422                                 if (ret == 0)
 423                                         t = __find_governor(str_governor);
 424                         }
 425
 426                         kfree(name);
 427                 }
 428
 429                 if (t != NULL) {
 430                         *governor = t;
 431                         err = 0;
 432                 }
 433
 434                 mutex_unlock(&cpufreq_governor_mutex);
 435         }
 436 out:
 437         return err;
 438 }
 439
 440
 441 /**
 442  * cpufreq_per_cpu_attr_read() / show_##file_name() -
 443  * print out cpufreq information
 444  *
 445  * Write out information from cpufreq_driver->policy[cpu]; object must be
 446  * "unsigned int".
 447  */
 448
 449 #define show_one(file_name, object)                     \
 450 static ssize_t show_##file_name                         \
 451 (struct cpufreq_policy *policy, char *buf)              \
 452 {                                                       \
 453         return sprintf(buf, "%u\n", policy->object);    \
 454 }
 455
 456 show_one(cpuinfo_min_freq, cpuinfo.min_freq);
 457 show_one(cpuinfo_max_freq, cpuinfo.max_freq);
 458 show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
 459 show_one(scaling_min_freq, min);
 460 show_one(scaling_max_freq, max);
 461 show_one(scaling_cur_freq, cur);
 462
 463 static int __cpufreq_set_policy(struct cpufreq_policy *data,
 464                                 struct cpufreq_policy *policy);
 465
 466 /**
 467  * cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
 468  */
 469 #define store_one(file_name, object)                    \
 470 static ssize_t store_##file_name                                        \
 471 (struct cpufreq_policy *policy, const char *buf, size_t count)          \
 472 {                                                                       \
 473         unsigned int ret = -EINVAL;                                     \
 474         struct cpufreq_policy new_policy;                               \
 475                                                                         \
 476         ret = cpufreq_get_policy(&new_policy, policy->cpu);             \
 477         if (ret)                                                        \
 478                 return -EINVAL;                                         \
 479                                                                         \
 480         ret = sscanf(buf, "%u", &new_policy.object);                    \
 481         if (ret != 1)                                                   \
 482                 return -EINVAL;                                         \
 483                                                                         \
 484         ret = __cpufreq_set_policy(policy, &new_policy);                \
 485         policy->user_policy.object = policy->object;                    \
 486                                                                         \
 487         return ret ? ret : count;                                       \
 488 }
 489
 490 store_one(scaling_min_freq, min);
 491 store_one(scaling_max_freq, max);
 492
 493 /**
 494  * show_cpuinfo_cur_freq - current CPU frequency as detected by hardware
 495  */
 496 static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
 497                                         char *buf)
 498 {
 499         unsigned int cur_freq = __cpufreq_get(policy->cpu);
 500         if (!cur_freq)
 501                 return sprintf(buf, "<unknown>");
 502         return sprintf(buf, "%u\n", cur_freq);
 503 }
 504
 505
 506 /**
 507  * show_scaling_governor - show the current policy for the specified CPU
 508  */
 509 static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf)
 510 {
 511         if (policy->policy == CPUFREQ_POLICY_POWERSAVE)
 512                 return sprintf(buf, "powersave\n");
 513         else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
 514                 return sprintf(buf, "performance\n");
 515         else if (policy->governor)
 516                 return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n",
 517                                 policy->governor->name);
 518         return -EINVAL;
 519 }
 520
 521
 522 /**
 523  * store_scaling_governor - store policy for the specified CPU
 524  */
 525 static ssize_t store_scaling_governor(struct cpufreq_policy *policy,
 526                                         const char *buf, size_t count)
 527 {
 528         unsigned int ret = -EINVAL;
 529         char    str_governor[16];
 530         struct cpufreq_policy new_policy;
 531
 532         ret = cpufreq_get_policy(&new_policy, policy->cpu);
 533         if (ret)
 534                 return ret;
 535
 536         ret = sscanf(buf, "%15s", str_governor);
 537         if (ret != 1)
 538                 return -EINVAL;
 539
 540         if (cpufreq_parse_governor(str_governor, &new_policy.policy,
 541                                                 &new_policy.governor))
 542                 return -EINVAL;
 543
 544         /* Do not use cpufreq_set_policy here or the user_policy.max
 545            will be wrongly overridden */
 546         ret = __cpufreq_set_policy(policy, &new_policy);
 547
 548         policy->user_policy.policy = policy->policy;
 549         policy->user_policy.governor = policy->governor;
 550
 551         if (ret)
 552                 return ret;
 553         else
 554                 return count;
 555 }
 556
 557 /**
 558  * show_scaling_driver - show the cpufreq driver currently loaded
 559  */
 560 static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
 561 {
 562         return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n", cpufreq_driver->name);
 563 }
 564
 565 /**
 566  * show_scaling_available_governors - show the available CPUfreq governors
 567  */
 568 static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
 569                                                 char *buf)
 570 {
 571         ssize_t i = 0;
 572         struct cpufreq_governor *t;
 573
 574         if (!cpufreq_driver->target) {
 575                 i += sprintf(buf, "performance powersave");
 576                 goto out;
 577         }
 578
 579         list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
 580                 if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
 581                     - (CPUFREQ_NAME_LEN + 2)))
 582                         goto out;
 583                 i += scnprintf(&buf[i], CPUFREQ_NAME_LEN, "%s ", t->name);
 584         }
 585 out:
 586         i += sprintf(&buf[i], "\n");
 587         return i;
 588 }
 589
 590 static ssize_t show_cpus(const struct cpumask *mask, char *buf)
 591 {
 592         ssize_t i = 0;
 593         unsigned int cpu;
 594
 595         for_each_cpu(cpu, mask) {
 596                 if (i)
 597                         i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), " ");
 598                 i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u", cpu);
 599                 if (i >= (PAGE_SIZE - 5))
 600                         break;
 601         }
 602         i += sprintf(&buf[i], "\n");
 603         return i;
 604 }
 605
 606 /**
 607  * show_related_cpus - show the CPUs affected by each transition even if
 608  * hw coordination is in use
 609  */
 610 static ssize_t show_related_cpus(struct cpufreq_policy *policy, char *buf)
 611 {
 612         if (cpumask_empty(policy->related_cpus))
 613                 return show_cpus(policy->cpus, buf);
 614         return show_cpus(policy->related_cpus, buf);
 615 }
 616
 617 /**
 618  * show_affected_cpus - show the CPUs affected by each transition
 619  */
 620 static ssize_t show_affected_cpus(struct cpufreq_policy *policy, char *buf)
 621 {
 622         return show_cpus(policy->cpus, buf);
 623 }
 624
 625 static ssize_t store_scaling_setspeed(struct cpufreq_policy *policy,
 626                                         const char *buf, size_t count)
 627 {
 628         unsigned int freq = 0;
 629         unsigned int ret;
 630
 631         if (!policy->governor || !policy->governor->store_setspeed)
 632                 return -EINVAL;
 633
 634         ret = sscanf(buf, "%u", &freq);
 635         if (ret != 1)
 636                 return -EINVAL;
 637
 638         policy->governor->store_setspeed(policy, freq);
 639
 640         return count;
 641 }
 642
 643 static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
 644 {
 645         if (!policy->governor || !policy->governor->show_setspeed)
 646                 return sprintf(buf, "<unsupported>\n");
 647
 648         return policy->governor->show_setspeed(policy, buf);
 649 }
 650
 651 /**
 652  * show_scaling_driver - show the current cpufreq HW/BIOS limitation
 653  */
 654 static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
 655 {
 656         unsigned int limit;
 657         int ret;
 658         if (cpufreq_driver->bios_limit) {
 659                 ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
 660                 if (!ret)
 661                         return sprintf(buf, "%u\n", limit);
 662         }
 663         return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
 664 }
 665
 666 cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);
 667 cpufreq_freq_attr_ro(cpuinfo_min_freq);
 668 cpufreq_freq_attr_ro(cpuinfo_max_freq);
 669 cpufreq_freq_attr_ro(cpuinfo_transition_latency);
 670 cpufreq_freq_attr_ro(scaling_available_governors);
 671 cpufreq_freq_attr_ro(scaling_driver);
 672 cpufreq_freq_attr_ro(scaling_cur_freq);
 673 cpufreq_freq_attr_ro(bios_limit);
 674 cpufreq_freq_attr_ro(related_cpus);
 675 cpufreq_freq_attr_ro(affected_cpus);
 676 cpufreq_freq_attr_rw(scaling_min_freq);
 677 cpufreq_freq_attr_rw(scaling_max_freq);
 678 cpufreq_freq_attr_rw(scaling_governor);
 679 cpufreq_freq_attr_rw(scaling_setspeed);
 680
 681 static struct attribute *default_attrs[] = {
 682         &cpuinfo_min_freq.attr,
 683         &cpuinfo_max_freq.attr,
 684         &cpuinfo_transition_latency.attr,
 685         &scaling_min_freq.attr,
 686         &scaling_max_freq.attr,
 687         &affected_cpus.attr,
 688         &related_cpus.attr,
 689         &scaling_governor.attr,
 690         &scaling_driver.attr,
 691         &scaling_available_governors.attr,
 692         &scaling_setspeed.attr,
 693         NULL
 694 };
 695
 696 struct kobject *cpufreq_global_kobject;
 697 EXPORT_SYMBOL(cpufreq_global_kobject);
 698
 699 #define to_policy(k) container_of(k, struct cpufreq_policy, kobj)
 700 #define to_attr(a) container_of(a, struct freq_attr, attr)
 701
 702 static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
 703 {
 704         struct cpufreq_policy *policy = to_policy(kobj);
 705         struct freq_attr *fattr = to_attr(attr);
 706         ssize_t ret = -EINVAL;
 707         policy = cpufreq_cpu_get(policy->cpu);
 708         if (!policy)
 709                 goto no_policy;
 710
 711         if (lock_policy_rwsem_read(policy->cpu) < 0)
 712                 goto fail;
 713
 714         if (fattr->show)
 715                 ret = fattr->show(policy, buf);
 716         else
 717                 ret = -EIO;
 718
 719         unlock_policy_rwsem_read(policy->cpu);
 720 fail:
 721         cpufreq_cpu_put(policy);
 722 no_policy:
 723         return ret;
 724 }
 725
 726 static ssize_t store(struct kobject *kobj, struct attribute *attr,
 727                      const char *buf, size_t count)
 728 {
 729         struct cpufreq_policy *policy = to_policy(kobj);
 730         struct freq_attr *fattr = to_attr(attr);
 731         ssize_t ret = -EINVAL;
 732         policy = cpufreq_cpu_get(policy->cpu);
 733         if (!policy)
 734                 goto no_policy;
 735
 736         if (lock_policy_rwsem_write(policy->cpu) < 0)
 737                 goto fail;
 738
 739         if (fattr->store)
 740                 ret = fattr->store(policy, buf, count);
 741         else
 742                 ret = -EIO;
 743
 744         unlock_policy_rwsem_write(policy->cpu);
 745 fail:
 746         cpufreq_cpu_put(policy);
 747 no_policy:
 748         return ret;
 749 }
 750
 751 static void cpufreq_sysfs_release(struct kobject *kobj)
 752 {
 753         struct cpufreq_policy *policy = to_policy(kobj);
 754         dprintk("last reference is dropped\n");
 755         complete(&policy->kobj_unregister);
 756 }
 757
 758 static const struct sysfs_ops sysfs_ops = {
 759         .show   = show,
 760         .store  = store,
 761 };
 762
 763 static struct kobj_type ktype_cpufreq = {
 764         .sysfs_ops      = &sysfs_ops,
 765         .default_attrs  = default_attrs,
 766         .release        = cpufreq_sysfs_release,
 767 };
 768
 769 /*
 770  * Returns:
 771  *   Negative: Failure
 772  *   0:        Success
 773  *   Positive: When we have a managed CPU and the sysfs got symlinked
 774  */
 775 static int cpufreq_add_dev_policy(unsigned int cpu,
 776                                   struct cpufreq_policy *policy,
 777                                   struct sys_device *sys_dev)
 778 {
 779         int ret = 0;
 780 #ifdef CONFIG_SMP
 781         unsigned long flags;
 782         unsigned int j;
 783 #ifdef CONFIG_HOTPLUG_CPU
 784         struct cpufreq_governor *gov;
 785
 786         gov = __find_governor(per_cpu(cpufreq_cpu_governor, cpu));
 787         if (gov) {
 788                 policy->governor = gov;
 789                 dprintk("Restoring governor %s for cpu %d\n",
 790                        policy->governor->name, cpu);
 791         }
 792 #endif
 793
 794         for_each_cpu(j, policy->cpus) {
 795                 struct cpufreq_policy *managed_policy;
 796
 797                 if (cpu == j)
 798                         continue;
 799
 800                 /* Check for existing affected CPUs.
 801                  * They may not be aware of it due to CPU Hotplug.
 802                  * cpufreq_cpu_put is called when the device is removed
 803                  * in __cpufreq_remove_dev()
 804                  */
 805                 managed_policy = cpufreq_cpu_get(j);
 806                 if (unlikely(managed_policy)) {
 807
 808                         /* Set proper policy_cpu */
 809                         unlock_policy_rwsem_write(cpu);
 810                         per_cpu(cpufreq_policy_cpu, cpu) = managed_policy->cpu;
 811
 812                         if (lock_policy_rwsem_write(cpu) < 0) {
 813                                 /* Should not go through policy unlock path */
 814                                 if (cpufreq_driver->exit)
 815                                         cpufreq_driver->exit(policy);
 816                                 cpufreq_cpu_put(managed_policy);
 817                                 return -EBUSY;
 818                         }
 819
 820                         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 821                         cpumask_copy(managed_policy->cpus, policy->cpus);
 822                         per_cpu(cpufreq_cpu_data, cpu) = managed_policy;
 823                         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 824
 825                         dprintk("CPU already managed, adding link\n");
 826                         ret = sysfs_create_link(&sys_dev->kobj,
 827                                                 &managed_policy->kobj,
 828                                                 "cpufreq");
 829                         if (ret)
 830                                 cpufreq_cpu_put(managed_policy);
 831                         /*
 832                          * Success. We only needed to be added to the mask.
 833                          * Call driver->exit() because only the cpu parent of
 834                          * the kobj needed to call init().
 835                          */
 836                         if (cpufreq_driver->exit)
 837                                 cpufreq_driver->exit(policy);
 838
 839                         if (!ret)
 840                                 return 1;
 841                         else
 842                                 return ret;
 843                 }
 844         }
 845 #endif
 846         return ret;
 847 }
 848
 849
 850 /* symlink affected CPUs */
 851 static int cpufreq_add_dev_symlink(unsigned int cpu,
 852                                    struct cpufreq_policy *policy)
 853 {
 854         unsigned int j;
 855         int ret = 0;
 856
 857         for_each_cpu(j, policy->cpus) {
 858                 struct cpufreq_policy *managed_policy;
 859                 struct sys_device *cpu_sys_dev;
 860
 861                 if (j == cpu)
 862                         continue;
 863                 if (!cpu_online(j))
 864                         continue;
 865
 866                 dprintk("CPU %u already managed, adding link\n", j);
 867                 managed_policy = cpufreq_cpu_get(cpu);
 868                 cpu_sys_dev = get_cpu_sysdev(j);
 869                 ret = sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj,
 870                                         "cpufreq");
 871                 if (ret) {
 872                         cpufreq_cpu_put(managed_policy);
 873                         return ret;
 874                 }
 875         }
 876         return ret;
 877 }
 878
 879 static int cpufreq_add_dev_interface(unsigned int cpu,
 880                                      struct cpufreq_policy *policy,
 881                                      struct sys_device *sys_dev)
 882 {
 883         struct cpufreq_policy new_policy;
 884         struct freq_attr **drv_attr;
 885         unsigned long flags;
 886         int ret = 0;
 887         unsigned int j;
 888
 889         /* prepare interface data */
 890         ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
 891                                    &sys_dev->kobj, "cpufreq");
 892         if (ret)
 893                 return ret;
 894
 895         /* set up files for this cpu device */
 896         drv_attr = cpufreq_driver->attr;
 897         while ((drv_attr) && (*drv_attr)) {
 898                 ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
 899                 if (ret)
 900                         goto err_out_kobj_put;
 901                 drv_attr++;
 902         }
 903         if (cpufreq_driver->get) {
 904                 ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
 905                 if (ret)
 906                         goto err_out_kobj_put;
 907         }
 908         if (cpufreq_driver->target) {
 909                 ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
 910                 if (ret)
 911                         goto err_out_kobj_put;
 912         }
 913         if (cpufreq_driver->bios_limit) {
 914                 ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
 915                 if (ret)
 916                         goto err_out_kobj_put;
 917         }
 918
 919         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 920         for_each_cpu(j, policy->cpus) {
 921                 if (!cpu_online(j))
 922                         continue;
 923                 per_cpu(cpufreq_cpu_data, j) = policy;
 924                 per_cpu(cpufreq_policy_cpu, j) = policy->cpu;
 925         }
 926         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 927
 928         ret = cpufreq_add_dev_symlink(cpu, policy);
 929         if (ret)
 930                 goto err_out_kobj_put;
 931
 932         memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
 933         /* assure that the starting sequence is run in __cpufreq_set_policy */
 934         policy->governor = NULL;
 935
 936         /* set default policy */
 937         ret = __cpufreq_set_policy(policy, &new_policy);
 938         policy->user_policy.policy = policy->policy;
 939         policy->user_policy.governor = policy->governor;
 940
 941         if (ret) {
 942                 dprintk("setting policy failed\n");
 943                 if (cpufreq_driver->exit)
 944                         cpufreq_driver->exit(policy);
 945         }
 946         return ret;
 947
 948 err_out_kobj_put:
 949         kobject_put(&policy->kobj);
 950         wait_for_completion(&policy->kobj_unregister);
 951         return ret;
 952 }
 953
 954
 955 /**
 956  * cpufreq_add_dev - add a CPU device
 957  *
 958  * Adds the cpufreq interface for a CPU device.
 959  *
 960  * The Oracle says: try running cpufreq registration/unregistration concurrently
 961  * with with cpu hotplugging and all hell will break loose. Tried to clean this
 962  * mess up, but more thorough testing is needed. - Mathieu
 963  */
 964 static int cpufreq_add_dev(struct sys_device *sys_dev)
 965 {
 966         unsigned int cpu = sys_dev->id;
 967         int ret = 0, found = 0;
 968         struct cpufreq_policy *policy;
 969         unsigned long flags;
 970         unsigned int j;
 971 #ifdef CONFIG_HOTPLUG_CPU
 972         int sibling;
 973 #endif
 974
 975         if (cpu_is_offline(cpu))
 976                 return 0;
 977
 978         cpufreq_debug_disable_ratelimit();
 979         dprintk("adding CPU %u\n", cpu);
 980
 981 #ifdef CONFIG_SMP
 982         /* check whether a different CPU already registered this
 983          * CPU because it is in the same boat. */
 984         policy = cpufreq_cpu_get(cpu);
 985         if (unlikely(policy)) {
 986                 cpufreq_cpu_put(policy);
 987                 cpufreq_debug_enable_ratelimit();
 988                 return 0;
 989         }
 990 #endif
 991
 992         if (!try_module_get(cpufreq_driver->owner)) {
 993                 ret = -EINVAL;
 994                 goto module_out;
 995         }
 996
 997         ret = -ENOMEM;
 998         policy = kzalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
 999         if (!policy)
1000                 goto nomem_out;
1001
1002         if (!alloc_cpumask_var(&policy->cpus, GFP_KERNEL))
1003                 goto err_free_policy;
1004
1005         if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL))
1006                 goto err_free_cpumask;
1007
1008         policy->cpu = cpu;
1009         cpumask_copy(policy->cpus, cpumask_of(cpu));
1010
1011         /* Initially set CPU itself as the policy_cpu */
1012         per_cpu(cpufreq_policy_cpu, cpu) = cpu;
1013         ret = (lock_policy_rwsem_write(cpu) < 0);
1014         WARN_ON(ret);
1015
1016         init_completion(&policy->kobj_unregister);
1017         INIT_WORK(&policy->update, handle_update);
1018
1019         /* Set governor before ->init, so that driver could check it */
1020 #ifdef CONFIG_HOTPLUG_CPU
1021         for_each_online_cpu(sibling) {
1022                 struct cpufreq_policy *cp = per_cpu(cpufreq_cpu_data, sibling);
1023                 if (cp && cp->governor &&
1024                     (cpumask_test_cpu(cpu, cp->related_cpus))) {
1025                         policy->governor = cp->governor;
1026                         found = 1;
1027                         break;
1028                 }
1029         }
1030 #endif
1031         if (!found)
1032                 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
1033         /* call driver. From then on the cpufreq must be able
1034          * to accept all calls to ->verify and ->setpolicy for this CPU
1035          */
1036         ret = cpufreq_driver->init(policy);
1037         if (ret) {
1038                 dprintk("initialization failed\n");
1039                 goto err_unlock_policy;
1040         }
1041         policy->user_policy.min = policy->min;
1042         policy->user_policy.max = policy->max;
1043
1044         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1045                                      CPUFREQ_START, policy);
1046
1047         ret = cpufreq_add_dev_policy(cpu, policy, sys_dev);
1048         if (ret) {
1049                 if (ret > 0)
1050                         /* This is a managed cpu, symlink created,
1051                            exit with 0 */
1052                         ret = 0;
1053                 goto err_unlock_policy;
1054         }
1055
1056         ret = cpufreq_add_dev_interface(cpu, policy, sys_dev);
1057         if (ret)
1058                 goto err_out_unregister;
1059
1060         unlock_policy_rwsem_write(cpu);
1061
1062         kobject_uevent(&policy->kobj, KOBJ_ADD);
1063         module_put(cpufreq_driver->owner);
1064         dprintk("initialization complete\n");
1065         cpufreq_debug_enable_ratelimit();
1066
1067         return 0;
1068
1069
1070 err_out_unregister:
1071         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1072         for_each_cpu(j, policy->cpus)
1073                 per_cpu(cpufreq_cpu_data, j) = NULL;
1074         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1075
1076         kobject_put(&policy->kobj);
1077         wait_for_completion(&policy->kobj_unregister);
1078
1079 err_unlock_policy:
1080         unlock_policy_rwsem_write(cpu);
1081         free_cpumask_var(policy->related_cpus);
1082 err_free_cpumask:
1083         free_cpumask_var(policy->cpus);
1084 err_free_policy:
1085         kfree(policy);
1086 nomem_out:
1087         module_put(cpufreq_driver->owner);
1088 module_out:
1089         cpufreq_debug_enable_ratelimit();
1090         return ret;
1091 }
1092
1093
1094 /**
1095  * __cpufreq_remove_dev - remove a CPU device
1096  *
1097  * Removes the cpufreq interface for a CPU device.
1098  * Caller should already have policy_rwsem in write mode for this CPU.
1099  * This routine frees the rwsem before returning.
1100  */
1101 static int __cpufreq_remove_dev(struct sys_device *sys_dev)
1102 {
1103         unsigned int cpu = sys_dev->id;
1104         unsigned long flags;
1105         struct cpufreq_policy *data;
1106         struct kobject *kobj;
1107         struct completion *cmp;
1108 #ifdef CONFIG_SMP
1109         struct sys_device *cpu_sys_dev;
1110         unsigned int j;
1111 #endif
1112
1113         cpufreq_debug_disable_ratelimit();
1114         dprintk("unregistering CPU %u\n", cpu);
1115
1116         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1117         data = per_cpu(cpufreq_cpu_data, cpu);
1118
1119         if (!data) {
1120                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1121                 cpufreq_debug_enable_ratelimit();
1122                 unlock_policy_rwsem_write(cpu);
1123                 return -EINVAL;
1124         }
1125         per_cpu(cpufreq_cpu_data, cpu) = NULL;
1126
1127
1128 #ifdef CONFIG_SMP
1129         /* if this isn't the CPU which is the parent of the kobj, we
1130          * only need to unlink, put and exit
1131          */
1132         if (unlikely(cpu != data->cpu)) {
1133                 dprintk("removing link\n");
1134                 cpumask_clear_cpu(cpu, data->cpus);
1135                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1136                 kobj = &sys_dev->kobj;
1137                 cpufreq_cpu_put(data);
1138                 cpufreq_debug_enable_ratelimit();
1139                 unlock_policy_rwsem_write(cpu);
1140                 sysfs_remove_link(kobj, "cpufreq");
1141                 return 0;
1142         }
1143 #endif
1144
1145 #ifdef CONFIG_SMP
1146
1147 #ifdef CONFIG_HOTPLUG_CPU
1148         strncpy(per_cpu(cpufreq_cpu_governor, cpu), data->governor->name,
1149                         CPUFREQ_NAME_LEN);
1150 #endif
1151
1152         /* if we have other CPUs still registered, we need to unlink them,
1153          * or else wait_for_completion below will lock up. Clean the
1154          * per_cpu(cpufreq_cpu_data) while holding the lock, and remove
1155          * the sysfs links afterwards.
1156          */
1157         if (unlikely(cpumask_weight(data->cpus) > 1)) {
1158                 for_each_cpu(j, data->cpus) {
1159                         if (j == cpu)
1160                                 continue;
1161                         per_cpu(cpufreq_cpu_data, j) = NULL;
1162                 }
1163         }
1164
1165         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1166
1167         if (unlikely(cpumask_weight(data->cpus) > 1)) {
1168                 for_each_cpu(j, data->cpus) {
1169                         if (j == cpu)
1170                                 continue;
1171                         dprintk("removing link for cpu %u\n", j);
1172 #ifdef CONFIG_HOTPLUG_CPU
1173                         strncpy(per_cpu(cpufreq_cpu_governor, j),
1174                                 data->governor->name, CPUFREQ_NAME_LEN);
1175 #endif
1176                         cpu_sys_dev = get_cpu_sysdev(j);
1177                         kobj = &cpu_sys_dev->kobj;
1178                         unlock_policy_rwsem_write(cpu);
1179                         sysfs_remove_link(kobj, "cpufreq");
1180                         lock_policy_rwsem_write(cpu);
1181                         cpufreq_cpu_put(data);
1182                 }
1183         }
1184 #else
1185         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1186 #endif
1187
1188         if (cpufreq_driver->target)
1189                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
1190
1191         kobj = &data->kobj;
1192         cmp = &data->kobj_unregister;
1193         unlock_policy_rwsem_write(cpu);
1194         kobject_put(kobj);
1195
1196         /* we need to make sure that the underlying kobj is actually
1197          * not referenced anymore by anybody before we proceed with
1198          * unloading.
1199          */
1200         dprintk("waiting for dropping of refcount\n");
1201         wait_for_completion(cmp);
1202         dprintk("wait complete\n");
1203
1204         lock_policy_rwsem_write(cpu);
1205         if (cpufreq_driver->exit)
1206                 cpufreq_driver->exit(data);
1207         unlock_policy_rwsem_write(cpu);
1208
1209         free_cpumask_var(data->related_cpus);
1210         free_cpumask_var(data->cpus);
1211         kfree(data);
1212         per_cpu(cpufreq_cpu_data, cpu) = NULL;
1213
1214         cpufreq_debug_enable_ratelimit();
1215         return 0;
1216 }
1217
1218
1219 static int cpufreq_remove_dev(struct sys_device *sys_dev)
1220 {
1221         unsigned int cpu = sys_dev->id;
1222         int retval;
1223
1224         if (cpu_is_offline(cpu))
1225                 return 0;
1226
1227         if (unlikely(lock_policy_rwsem_write(cpu)))
1228                 BUG();
1229
1230         retval = __cpufreq_remove_dev(sys_dev);
1231         return retval;
1232 }
1233
1234
1235 static void handle_update(struct work_struct *work)
1236 {
1237         struct cpufreq_policy *policy =
1238                 container_of(work, struct cpufreq_policy, update);
1239         unsigned int cpu = policy->cpu;
1240         dprintk("handle_update for cpu %u called\n", cpu);
1241         cpufreq_update_policy(cpu);
1242 }
1243
1244 /**
1245  *      cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're in deep trouble.
1246  *      @cpu: cpu number
1247  *      @old_freq: CPU frequency the kernel thinks the CPU runs at
1248  *      @new_freq: CPU frequency the CPU actually runs at
1249  *
1250  *      We adjust to current frequency first, and need to clean up later.
1251  *      So either call to cpufreq_update_policy() or schedule handle_update()).
1252  */
1253 static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq,
1254                                 unsigned int new_freq)
1255 {
1256         struct cpufreq_freqs freqs;
1257
1258         dprintk("Warning: CPU frequency out of sync: cpufreq and timing "
1259                "core thinks of %u, is %u kHz.\n", old_freq, new_freq);
1260
1261         freqs.cpu = cpu;
1262         freqs.old = old_freq;
1263         freqs.new = new_freq;
1264         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
1265         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
1266 }
1267
1268
1269 /**
1270  * cpufreq_quick_get - get the CPU frequency (in kHz) from policy->cur
1271  * @cpu: CPU number
1272  *
1273  * This is the last known freq, without actually getting it from the driver.
1274  * Return value will be same as what is shown in scaling_cur_freq in sysfs.
1275  */
1276 unsigned int cpufreq_quick_get(unsigned int cpu)
1277 {
1278         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
1279         unsigned int ret_freq = 0;
1280
1281         if (policy) {
1282                 ret_freq = policy->cur;
1283                 cpufreq_cpu_put(policy);
1284         }
1285
1286         return ret_freq;
1287 }
1288 EXPORT_SYMBOL(cpufreq_quick_get);
1289
1290
1291 static unsigned int __cpufreq_get(unsigned int cpu)
1292 {
1293         struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
1294         unsigned int ret_freq = 0;
1295
1296         if (!cpufreq_driver->get)
1297                 return ret_freq;
1298
1299         ret_freq = cpufreq_driver->get(cpu);
1300
1301         if (ret_freq && policy->cur &&
1302                 !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
1303                 /* verify no discrepancy between actual and
1304                                         saved value exists */
1305                 if (unlikely(ret_freq != policy->cur)) {
1306                         cpufreq_out_of_sync(cpu, policy->cur, ret_freq);
1307                         schedule_work(&policy->update);
1308                 }
1309         }
1310
1311         return ret_freq;
1312 }
1313
1314 /**
1315  * cpufreq_get - get the current CPU frequency (in kHz)
1316  * @cpu: CPU number
1317  *
1318  * Get the CPU current (static) CPU frequency
1319  */
1320 unsigned int cpufreq_get(unsigned int cpu)
1321 {
1322         unsigned int ret_freq = 0;
1323         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
1324
1325         if (!policy)
1326                 goto out;
1327
1328         if (unlikely(lock_policy_rwsem_read(cpu)))
1329                 goto out_policy;
1330
1331         ret_freq = __cpufreq_get(cpu);
1332
1333         unlock_policy_rwsem_read(cpu);
1334
1335 out_policy:
1336         cpufreq_cpu_put(policy);
1337 out:
1338         return ret_freq;
1339 }
1340 EXPORT_SYMBOL(cpufreq_get);
1341
1342
1343 /**
1344  *      cpufreq_suspend - let the low level driver prepare for suspend
1345  */
1346
1347 static int cpufreq_suspend(struct sys_device *sysdev, pm_message_t pmsg)
1348 {
1349         int ret = 0;
1350
1351         int cpu = sysdev->id;
1352         struct cpufreq_policy *cpu_policy;
1353
1354         dprintk("suspending cpu %u\n", cpu);
1355
1356         if (!cpu_online(cpu))
1357                 return 0;
1358
1359         /* we may be lax here as interrupts are off. Nonetheless
1360          * we need to grab the correct cpu policy, as to check
1361          * whether we really run on this CPU.
1362          */
1363
1364         cpu_policy = cpufreq_cpu_get(cpu);
1365         if (!cpu_policy)
1366                 return -EINVAL;
1367
1368         /* only handle each CPU group once */
1369         if (unlikely(cpu_policy->cpu != cpu))
1370                 goto out;
1371
1372         if (cpufreq_driver->suspend) {
1373                 ret = cpufreq_driver->suspend(cpu_policy, pmsg);
1374                 if (ret)
1375                         printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
1376                                         "step on CPU %u\n", cpu_policy->cpu);
1377         }
1378
1379 out:
1380         cpufreq_cpu_put(cpu_policy);
1381         return ret;
1382 }
1383
1384 /**
1385  *      cpufreq_resume -  restore proper CPU frequency handling after resume
1386  *
1387  *      1.) resume CPUfreq hardware support (cpufreq_driver->resume())
1388  *      2.) schedule call cpufreq_update_policy() ASAP as interrupts are
1389  *          restored. It will verify that the current freq is in sync with
1390  *          what we believe it to be. This is a bit later than when it
1391  *          should be, but nonethteless it's better than calling
1392  *          cpufreq_driver->get() here which might re-enable interrupts...
1393  */
1394 static int cpufreq_resume(struct sys_device *sysdev)
1395 {
1396         int ret = 0;
1397
1398         int cpu = sysdev->id;
1399         struct cpufreq_policy *cpu_policy;
1400
1401         dprintk("resuming cpu %u\n", cpu);
1402
1403         if (!cpu_online(cpu))
1404                 return 0;
1405
1406         /* we may be lax here as interrupts are off. Nonetheless
1407          * we need to grab the correct cpu policy, as to check
1408          * whether we really run on this CPU.
1409          */
1410
1411         cpu_policy = cpufreq_cpu_get(cpu);
1412         if (!cpu_policy)
1413                 return -EINVAL;
1414
1415         /* only handle each CPU group once */
1416         if (unlikely(cpu_policy->cpu != cpu))
1417                 goto fail;
1418
1419         if (cpufreq_driver->resume) {
1420                 ret = cpufreq_driver->resume(cpu_policy);
1421                 if (ret) {
1422                         printk(KERN_ERR "cpufreq: resume failed in ->resume "
1423                                         "step on CPU %u\n", cpu_policy->cpu);
1424                         goto fail;
1425                 }
1426         }
1427
1428         schedule_work(&cpu_policy->update);
1429
1430 fail:
1431         cpufreq_cpu_put(cpu_policy);
1432         return ret;
1433 }
1434
1435 static struct sysdev_driver cpufreq_sysdev_driver = {
1436         .add            = cpufreq_add_dev,
1437         .remove         = cpufreq_remove_dev,
1438         .suspend        = cpufreq_suspend,
1439         .resume         = cpufreq_resume,
1440 };
1441
1442
1443 /*********************************************************************
1444  *                     NOTIFIER LISTS INTERFACE                      *
1445  *********************************************************************/
1446
1447 /**
1448  *      cpufreq_register_notifier - register a driver with cpufreq
1449  *      @nb: notifier function to register
1450  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
1451  *
1452  *      Add a driver to one of two lists: either a list of drivers that
1453  *      are notified about clock rate changes (once before and once after
1454  *      the transition), or a list of drivers that are notified about
1455  *      changes in cpufreq policy.
1456  *
1457  *      This function may sleep, and has the same return conditions as
1458  *      blocking_notifier_chain_register.
1459  */
1460 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
1461 {
1462         int ret;
1463
1464         WARN_ON(!init_cpufreq_transition_notifier_list_called);
1465
1466         switch (list) {
1467         case CPUFREQ_TRANSITION_NOTIFIER:
1468                 ret = srcu_notifier_chain_register(
1469                                 &cpufreq_transition_notifier_list, nb);
1470                 break;
1471         case CPUFREQ_POLICY_NOTIFIER:
1472                 ret = blocking_notifier_chain_register(
1473                                 &cpufreq_policy_notifier_list, nb);
1474                 break;
1475         default:
1476                 ret = -EINVAL;
1477         }
1478
1479         return ret;
1480 }
1481 EXPORT_SYMBOL(cpufreq_register_notifier);
1482
1483
1484 /**
1485  *      cpufreq_unregister_notifier - unregister a driver with cpufreq
1486  *      @nb: notifier block to be unregistered
1487  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
1488  *
1489  *      Remove a driver from the CPU frequency notifier list.
1490  *
1491  *      This function may sleep, and has the same return conditions as
1492  *      blocking_notifier_chain_unregister.
1493  */
1494 int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
1495 {
1496         int ret;
1497
1498         switch (list) {
1499         case CPUFREQ_TRANSITION_NOTIFIER:
1500                 ret = srcu_notifier_chain_unregister(
1501                                 &cpufreq_transition_notifier_list, nb);
1502                 break;
1503         case CPUFREQ_POLICY_NOTIFIER:
1504                 ret = blocking_notifier_chain_unregister(
1505                                 &cpufreq_policy_notifier_list, nb);
1506                 break;
1507         default:
1508                 ret = -EINVAL;
1509         }
1510
1511         return ret;
1512 }
1513 EXPORT_SYMBOL(cpufreq_unregister_notifier);
1514
1515
1516 /*********************************************************************
1517  *                              GOVERNORS                            *
1518  *********************************************************************/
1519
1520
1521 int __cpufreq_driver_target(struct cpufreq_policy *policy,
1522                             unsigned int target_freq,
1523                             unsigned int relation)
1524 {
1525         int retval = -EINVAL;
1526
1527         dprintk("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
1528                 target_freq, relation);
1529         if (cpu_online(policy->cpu) && cpufreq_driver->target)
1530                 retval = cpufreq_driver->target(policy, target_freq, relation);
1531
1532         return retval;
1533 }
1534 EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
1535
1536 int cpufreq_driver_target(struct cpufreq_policy *policy,
1537                           unsigned int target_freq,
1538                           unsigned int relation)
1539 {
1540         int ret = -EINVAL;
1541
1542         policy = cpufreq_cpu_get(policy->cpu);
1543         if (!policy)
1544                 goto no_policy;
1545
1546         if (unlikely(lock_policy_rwsem_write(policy->cpu)))
1547                 goto fail;
1548
1549         ret = __cpufreq_driver_target(policy, target_freq, relation);
1550
1551         unlock_policy_rwsem_write(policy->cpu);
1552
1553 fail:
1554         cpufreq_cpu_put(policy);
1555 no_policy:
1556         return ret;
1557 }
1558 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
1559
1560 int __cpufreq_driver_getavg(struct cpufreq_policy *policy, unsigned int cpu)
1561 {
1562         int ret = 0;
1563
1564         policy = cpufreq_cpu_get(policy->cpu);
1565         if (!policy)
1566                 return -EINVAL;
1567
1568         if (cpu_online(cpu) && cpufreq_driver->getavg)
1569                 ret = cpufreq_driver->getavg(policy, cpu);
1570
1571         cpufreq_cpu_put(policy);
1572         return ret;
1573 }
1574 EXPORT_SYMBOL_GPL(__cpufreq_driver_getavg);
1575
1576 /*
1577  * when "event" is CPUFREQ_GOV_LIMITS
1578  */
1579
1580 static int __cpufreq_governor(struct cpufreq_policy *policy,
1581                                         unsigned int event)
1582 {
1583         int ret;
1584
1585         /* Only must be defined when default governor is known to have latency
1586            restrictions, like e.g. conservative or ondemand.
1587            That this is the case is already ensured in Kconfig
1588         */
1589 #ifdef CONFIG_CPU_FREQ_GOV_PERFORMANCE
1590         struct cpufreq_governor *gov = &cpufreq_gov_performance;
1591 #else
1592         struct cpufreq_governor *gov = NULL;
1593 #endif
1594
1595         if (policy->governor->max_transition_latency &&
1596             policy->cpuinfo.transition_latency >
1597             policy->governor->max_transition_latency) {
1598                 if (!gov)
1599                         return -EINVAL;
1600                 else {
1601                         printk(KERN_WARNING "%s governor failed, too long"
1602                                " transition latency of HW, fallback"
1603                                " to %s governor\n",
1604                                policy->governor->name,
1605                                gov->name);
1606                         policy->governor = gov;
1607                 }
1608         }
1609
1610         if (!try_module_get(policy->governor->owner))
1611                 return -EINVAL;
1612
1613         dprintk("__cpufreq_governor for CPU %u, event %u\n",
1614                                                 policy->cpu, event);
1615         ret = policy->governor->governor(policy, event);
1616
1617         /* we keep one module reference alive for
1618                         each CPU governed by this CPU */
1619         if ((event != CPUFREQ_GOV_START) || ret)
1620                 module_put(policy->governor->owner);
1621         if ((event == CPUFREQ_GOV_STOP) && !ret)
1622                 module_put(policy->governor->owner);
1623
1624         return ret;
1625 }
1626
1627
1628 int cpufreq_register_governor(struct cpufreq_governor *governor)
1629 {
1630         int err;
1631
1632         if (!governor)
1633                 return -EINVAL;
1634
1635         mutex_lock(&cpufreq_governor_mutex);
1636
1637         err = -EBUSY;
1638         if (__find_governor(governor->name) == NULL) {
1639                 err = 0;
1640                 list_add(&governor->governor_list, &cpufreq_governor_list);
1641         }
1642
1643         mutex_unlock(&cpufreq_governor_mutex);
1644         return err;
1645 }
1646 EXPORT_SYMBOL_GPL(cpufreq_register_governor);
1647
1648
1649 void cpufreq_unregister_governor(struct cpufreq_governor *governor)
1650 {
1651 #ifdef CONFIG_HOTPLUG_CPU
1652         int cpu;
1653 #endif
1654
1655         if (!governor)
1656                 return;
1657
1658 #ifdef CONFIG_HOTPLUG_CPU
1659         for_each_present_cpu(cpu) {
1660                 if (cpu_online(cpu))
1661                         continue;
1662                 if (!strcmp(per_cpu(cpufreq_cpu_governor, cpu), governor->name))
1663                         strcpy(per_cpu(cpufreq_cpu_governor, cpu), "\0");
1664         }
1665 #endif
1666
1667         mutex_lock(&cpufreq_governor_mutex);
1668         list_del(&governor->governor_list);
1669         mutex_unlock(&cpufreq_governor_mutex);
1670         return;
1671 }
1672 EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
1673
1674
1675
1676 /*********************************************************************
1677  *                          POLICY INTERFACE                         *
1678  *********************************************************************/
1679
1680 /**
1681  * cpufreq_get_policy - get the current cpufreq_policy
1682  * @policy: struct cpufreq_policy into which the current cpufreq_policy
1683  *      is written
1684  *
1685  * Reads the current cpufreq policy.
1686  */
1687 int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
1688 {
1689         struct cpufreq_policy *cpu_policy;
1690         if (!policy)
1691                 return -EINVAL;
1692
1693         cpu_policy = cpufreq_cpu_get(cpu);
1694         if (!cpu_policy)
1695                 return -EINVAL;
1696
1697         memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
1698
1699         cpufreq_cpu_put(cpu_policy);
1700         return 0;
1701 }
1702 EXPORT_SYMBOL(cpufreq_get_policy);
1703
1704
1705 /*
1706  * data   : current policy.
1707  * policy : policy to be set.
1708  */
1709 static int __cpufreq_set_policy(struct cpufreq_policy *data,
1710                                 struct cpufreq_policy *policy)
1711 {
1712         int ret = 0;
1713
1714         cpufreq_debug_disable_ratelimit();
1715         dprintk("setting new policy for CPU %u: %u - %u kHz\n", policy->cpu,
1716                 policy->min, policy->max);
1717
1718         memcpy(&policy->cpuinfo, &data->cpuinfo,
1719                                 sizeof(struct cpufreq_cpuinfo));
1720
1721         if (policy->min > data->max || policy->max < data->min) {
1722                 ret = -EINVAL;
1723                 goto error_out;
1724         }
1725
1726         /* verify the cpu speed can be set within this limit */
1727         ret = cpufreq_driver->verify(policy);
1728         if (ret)
1729                 goto error_out;
1730
1731         /* adjust if necessary - all reasons */
1732         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1733                         CPUFREQ_ADJUST, policy);
1734
1735         /* adjust if necessary - hardware incompatibility*/
1736         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1737                         CPUFREQ_INCOMPATIBLE, policy);
1738
1739         /* verify the cpu speed can be set within this limit,
1740            which might be different to the first one */
1741         ret = cpufreq_driver->verify(policy);
1742         if (ret)
1743                 goto error_out;
1744
1745         /* notification of the new policy */
1746         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1747                         CPUFREQ_NOTIFY, policy);
1748
1749         data->min = policy->min;
1750         data->max = policy->max;
1751
1752         dprintk("new min and max freqs are %u - %u kHz\n",
1753                                         data->min, data->max);
1754
1755         if (cpufreq_driver->setpolicy) {
1756                 data->policy = policy->policy;
1757                 dprintk("setting range\n");
1758                 ret = cpufreq_driver->setpolicy(policy);
1759         } else {
1760                 if (policy->governor != data->governor) {
1761                         /* save old, working values */
1762                         struct cpufreq_governor *old_gov = data->governor;
1763
1764                         dprintk("governor switch\n");
1765
1766                         /* end old governor */
1767                         if (data->governor)
1768                                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
1769
1770                         /* start new governor */
1771                         data->governor = policy->governor;
1772                         if (__cpufreq_governor(data, CPUFREQ_GOV_START)) {
1773                                 /* new governor failed, so re-start old one */
1774                                 dprintk("starting governor %s failed\n",
1775                                                         data->governor->name);
1776                                 if (old_gov) {
1777                                         data->governor = old_gov;
1778                                         __cpufreq_governor(data,
1779                                                            CPUFREQ_GOV_START);
1780                                 }
1781                                 ret = -EINVAL;
1782                                 goto error_out;
1783                         }
1784                         /* might be a policy change, too, so fall through */
1785                 }
1786                 dprintk("governor: change or update limits\n");
1787                 __cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
1788         }
1789
1790 error_out:
1791         cpufreq_debug_enable_ratelimit();
1792         return ret;
1793 }
1794
1795 /**
1796  *      cpufreq_update_policy - re-evaluate an existing cpufreq policy
1797  *      @cpu: CPU which shall be re-evaluated
1798  *
1799  *      Usefull for policy notifiers which have different necessities
1800  *      at different times.
1801  */
1802 int cpufreq_update_policy(unsigned int cpu)
1803 {
1804         struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
1805         struct cpufreq_policy policy;
1806         int ret;
1807
1808         if (!data) {
1809                 ret = -ENODEV;
1810                 goto no_policy;
1811         }
1812
1813         if (unlikely(lock_policy_rwsem_write(cpu))) {
1814                 ret = -EINVAL;
1815                 goto fail;
1816         }
1817
1818         dprintk("updating policy for CPU %u\n", cpu);
1819         memcpy(&policy, data, sizeof(struct cpufreq_policy));
1820         policy.min = data->user_policy.min;
1821         policy.max = data->user_policy.max;
1822         policy.policy = data->user_policy.policy;
1823         policy.governor = data->user_policy.governor;
1824
1825         /* BIOS might change freq behind our back
1826           -> ask driver for current freq and notify governors about a change */
1827         if (cpufreq_driver->get) {
1828                 policy.cur = cpufreq_driver->get(cpu);
1829                 if (!data->cur) {
1830                         dprintk("Driver did not initialize current freq");
1831                         data->cur = policy.cur;
1832                 } else {
1833                         if (data->cur != policy.cur)
1834                                 cpufreq_out_of_sync(cpu, data->cur,
1835                                                                 policy.cur);
1836                 }
1837         }
1838
1839         ret = __cpufreq_set_policy(data, &policy);
1840
1841         unlock_policy_rwsem_write(cpu);
1842
1843 fail:
1844         cpufreq_cpu_put(data);
1845 no_policy:
1846         return ret;
1847 }
1848 EXPORT_SYMBOL(cpufreq_update_policy);
1849
1850 static int __cpuinit cpufreq_cpu_callback(struct notifier_block *nfb,
1851                                         unsigned long action, void *hcpu)
1852 {
1853         unsigned int cpu = (unsigned long)hcpu;
1854         struct sys_device *sys_dev;
1855
1856         sys_dev = get_cpu_sysdev(cpu);
1857         if (sys_dev) {
1858                 switch (action) {
1859                 case CPU_ONLINE:
1860                 case CPU_ONLINE_FROZEN:
1861                         cpufreq_add_dev(sys_dev);
1862                         break;
1863                 case CPU_DOWN_PREPARE:
1864                 case CPU_DOWN_PREPARE_FROZEN:
1865                         if (unlikely(lock_policy_rwsem_write(cpu)))
1866                                 BUG();
1867
1868                         __cpufreq_remove_dev(sys_dev);
1869                         break;
1870                 case CPU_DOWN_FAILED:
1871                 case CPU_DOWN_FAILED_FROZEN:
1872                         cpufreq_add_dev(sys_dev);
1873                         break;
1874                 }
1875         }
1876         return NOTIFY_OK;
1877 }
1878
1879 static struct notifier_block __refdata cpufreq_cpu_notifier = {
1880     .notifier_call = cpufreq_cpu_callback,
1881 };
1882
1883 /*********************************************************************
1884  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
1885  *********************************************************************/
1886
1887 /**
1888  * cpufreq_register_driver - register a CPU Frequency driver
1889  * @driver_data: A struct cpufreq_driver containing the values#
1890  * submitted by the CPU Frequency driver.
1891  *
1892  *   Registers a CPU Frequency driver to this core code. This code
1893  * returns zero on success, -EBUSY when another driver got here first
1894  * (and isn't unregistered in the meantime).
1895  *
1896  */
1897 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
1898 {
1899         unsigned long flags;
1900         int ret;
1901
1902         if (!driver_data || !driver_data->verify || !driver_data->init ||
1903             ((!driver_data->setpolicy) && (!driver_data->target)))
1904                 return -EINVAL;
1905
1906         dprintk("trying to register driver %s\n", driver_data->name);
1907
1908         if (driver_data->setpolicy)
1909                 driver_data->flags |= CPUFREQ_CONST_LOOPS;
1910
1911         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1912         if (cpufreq_driver) {
1913                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1914                 return -EBUSY;
1915         }
1916         cpufreq_driver = driver_data;
1917         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1918
1919         ret = sysdev_driver_register(&cpu_sysdev_class,
1920                                         &cpufreq_sysdev_driver);
1921
1922         if ((!ret) && !(cpufreq_driver->flags & CPUFREQ_STICKY)) {
1923                 int i;
1924                 ret = -ENODEV;
1925
1926                 /* check for at least one working CPU */
1927                 for (i = 0; i < nr_cpu_ids; i++)
1928                         if (cpu_possible(i) && per_cpu(cpufreq_cpu_data, i)) {
1929                                 ret = 0;
1930                                 break;
1931                         }
1932
1933                 /* if all ->init() calls failed, unregister */
1934                 if (ret) {
1935                         dprintk("no CPU initialized for driver %s\n",
1936                                                         driver_data->name);
1937                         sysdev_driver_unregister(&cpu_sysdev_class,
1938                                                 &cpufreq_sysdev_driver);
1939
1940                         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1941                         cpufreq_driver = NULL;
1942                         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1943                 }
1944         }
1945
1946         if (!ret) {
1947                 register_hotcpu_notifier(&cpufreq_cpu_notifier);
1948                 dprintk("driver %s up and running\n", driver_data->name);
1949                 cpufreq_debug_enable_ratelimit();
1950         }
1951
1952         return ret;
1953 }
1954 EXPORT_SYMBOL_GPL(cpufreq_register_driver);
1955
1956
1957 /**
1958  * cpufreq_unregister_driver - unregister the current CPUFreq driver
1959  *
1960  *    Unregister the current CPUFreq driver. Only call this if you have
1961  * the right to do so, i.e. if you have succeeded in initialising before!
1962  * Returns zero if successful, and -EINVAL if the cpufreq_driver is
1963  * currently not initialised.
1964  */
1965 int cpufreq_unregister_driver(struct cpufreq_driver *driver)
1966 {
1967         unsigned long flags;
1968
1969         cpufreq_debug_disable_ratelimit();
1970
1971         if (!cpufreq_driver || (driver != cpufreq_driver)) {
1972                 cpufreq_debug_enable_ratelimit();
1973                 return -EINVAL;
1974         }
1975
1976         dprintk("unregistering driver %s\n", driver->name);
1977
1978         sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
1979         unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
1980
1981         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1982         cpufreq_driver = NULL;
1983         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1984
1985         return 0;
1986 }
1987 EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
1988
1989 static int __init cpufreq_core_init(void)
1990 {
1991         int cpu;
1992
1993         for_each_possible_cpu(cpu) {
1994                 per_cpu(cpufreq_policy_cpu, cpu) = -1;
1995                 init_rwsem(&per_cpu(cpu_policy_rwsem, cpu));
1996         }
1997
1998         cpufreq_global_kobject = kobject_create_and_add("cpufreq",
1999                                                 &cpu_sysdev_class.kset.kobj);
2000         BUG_ON(!cpufreq_global_kobject);
2001
2002         return 0;
2003 }
2004 core_initcall(cpufreq_core_init);