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 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_CORE, \
  33                                                 "cpufreq-core", msg)
  34
  35 /**
  36  * The "cpufreq driver" - the arch- or hardware-dependent low
  37  * level driver of CPUFreq support, and its spinlock. This lock
  38  * also protects the cpufreq_cpu_data array.
  39  */
  40 static struct cpufreq_driver *cpufreq_driver;
  41 static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
  42 #ifdef CONFIG_HOTPLUG_CPU
  43 /* This one keeps track of the previously set governor of a removed CPU */
  44 static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
  45 #endif
  46 static DEFINE_SPINLOCK(cpufreq_driver_lock);
  47
  48 /*
  49  * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
  50  * all cpufreq/hotplug/workqueue/etc related lock issues.
  51  *
  52  * The rules for this semaphore:
  53  * - Any routine that wants to read from the policy structure will
  54  *   do a down_read on this semaphore.
  55  * - Any routine that will write to the policy structure and/or may take away
  56  *   the policy altogether (eg. CPU hotplug), will hold this lock in write
  57  *   mode before doing so.
  58  *
  59  * Additional rules:
  60  * - All holders of the lock should check to make sure that the CPU they
  61  *   are concerned with are online after they get the lock.
  62  * - Governor routines that can be called in cpufreq hotplug path should not
  63  *   take this sem as top level hotplug notifier handler takes this.
  64  * - Lock should not be held across
  65  *     __cpufreq_governor(data, CPUFREQ_GOV_STOP);
  66  */
  67 static DEFINE_PER_CPU(int, cpufreq_policy_cpu);
  68 static DEFINE_PER_CPU(struct rw_semaphore, cpu_policy_rwsem);
  69
  70 #define lock_policy_rwsem(mode, cpu)                                    \
  71 int lock_policy_rwsem_##mode                                            \
  72 (int cpu)                                                               \
  73 {                                                                       \
  74         int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);              \
  75         BUG_ON(policy_cpu == -1);                                       \
  76         down_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu));            \
  77         if (unlikely(!cpu_online(cpu))) {                               \
  78                 up_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu));      \
  79                 return -1;                                              \
  80         }                                                               \
  81                                                                         \
  82         return 0;                                                       \
  83 }
  84
  85 lock_policy_rwsem(read, cpu);
  86 EXPORT_SYMBOL_GPL(lock_policy_rwsem_read);
  87
  88 lock_policy_rwsem(write, cpu);
  89 EXPORT_SYMBOL_GPL(lock_policy_rwsem_write);
  90
  91 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 EXPORT_SYMBOL_GPL(unlock_policy_rwsem_read);
  98
  99 void unlock_policy_rwsem_write(int cpu)
 100 {
 101         int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);
 102         BUG_ON(policy_cpu == -1);
 103         up_write(&per_cpu(cpu_policy_rwsem, policy_cpu));
 104 }
 105 EXPORT_SYMBOL_GPL(unlock_policy_rwsem_write);
 106
 107
 108 /* internal prototypes */
 109 static int __cpufreq_governor(struct cpufreq_policy *policy,
 110                 unsigned int event);
 111 static unsigned int __cpufreq_get(unsigned int cpu);
 112 static void handle_update(struct work_struct *work);
 113
 114 /**
 115  * Two notifier lists: the "policy" list is involved in the
 116  * validation process for a new CPU frequency policy; the
 117  * "transition" list for kernel code that needs to handle
 118  * changes to devices when the CPU clock speed changes.
 119  * The mutex locks both lists.
 120  */
 121 static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
 122 static struct srcu_notifier_head cpufreq_transition_notifier_list;
 123
 124 static bool init_cpufreq_transition_notifier_list_called;
 125 static int __init init_cpufreq_transition_notifier_list(void)
 126 {
 127         srcu_init_notifier_head(&cpufreq_transition_notifier_list);
 128         init_cpufreq_transition_notifier_list_called = true;
 129         return 0;
 130 }
 131 pure_initcall(init_cpufreq_transition_notifier_list);
 132
 133 static LIST_HEAD(cpufreq_governor_list);
 134 static DEFINE_MUTEX(cpufreq_governor_mutex);
 135
 136 struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
 137 {
 138         struct cpufreq_policy *data;
 139         unsigned long flags;
 140
 141         if (cpu >= nr_cpu_ids)
 142                 goto err_out;
 143
 144         /* get the cpufreq driver */
 145         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 146
 147         if (!cpufreq_driver)
 148                 goto err_out_unlock;
 149
 150         if (!try_module_get(cpufreq_driver->owner))
 151                 goto err_out_unlock;
 152
 153
 154         /* get the CPU */
 155         data = per_cpu(cpufreq_cpu_data, cpu);
 156
 157         if (!data)
 158                 goto err_out_put_module;
 159
 160         if (!kobject_get(&data->kobj))
 161                 goto err_out_put_module;
 162
 163         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 164         return data;
 165
 166 err_out_put_module:
 167         module_put(cpufreq_driver->owner);
 168 err_out_unlock:
 169         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 170 err_out:
 171         return NULL;
 172 }
 173 EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
 174
 175
 176 void cpufreq_cpu_put(struct cpufreq_policy *data)
 177 {
 178         kobject_put(&data->kobj);
 179         module_put(cpufreq_driver->owner);
 180 }
 181 EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
 182
 183
 184 /*********************************************************************
 185  *                     UNIFIED DEBUG HELPERS                         *
 186  *********************************************************************/
 187 #ifdef CONFIG_CPU_FREQ_DEBUG
 188
 189 /* what part(s) of the CPUfreq subsystem are debugged? */
 190 static unsigned int debug;
 191
 192 /* is the debug output ratelimit'ed using printk_ratelimit? User can
 193  * set or modify this value.
 194  */
 195 static unsigned int debug_ratelimit = 1;
 196
 197 /* is the printk_ratelimit'ing enabled? It's enabled after a successful
 198  * loading of a cpufreq driver, temporarily disabled when a new policy
 199  * is set, and disabled upon cpufreq driver removal
 200  */
 201 static unsigned int disable_ratelimit = 1;
 202 static DEFINE_SPINLOCK(disable_ratelimit_lock);
 203
 204 static void cpufreq_debug_enable_ratelimit(void)
 205 {
 206         unsigned long flags;
 207
 208         spin_lock_irqsave(&disable_ratelimit_lock, flags);
 209         if (disable_ratelimit)
 210                 disable_ratelimit--;
 211         spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
 212 }
 213
 214 static void cpufreq_debug_disable_ratelimit(void)
 215 {
 216         unsigned long flags;
 217
 218         spin_lock_irqsave(&disable_ratelimit_lock, flags);
 219         disable_ratelimit++;
 220         spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
 221 }
 222
 223 void cpufreq_debug_printk(unsigned int type, const char *prefix,
 224                         const char *fmt, ...)
 225 {
 226         char s[256];
 227         va_list args;
 228         unsigned int len;
 229         unsigned long flags;
 230
 231         WARN_ON(!prefix);
 232         if (type & debug) {
 233                 spin_lock_irqsave(&disable_ratelimit_lock, flags);
 234                 if (!disable_ratelimit && debug_ratelimit
 235                                         && !printk_ratelimit()) {
 236                         spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
 237                         return;
 238                 }
 239                 spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
 240
 241                 len = snprintf(s, 256, KERN_DEBUG "%s: ", prefix);
 242
 243                 va_start(args, fmt);
 244                 len += vsnprintf(&s[len], (256 - len), fmt, args);
 245                 va_end(args);
 246
 247                 printk(s);
 248
 249                 WARN_ON(len < 5);
 250         }
 251 }
 252 EXPORT_SYMBOL(cpufreq_debug_printk);
 253
 254
 255 module_param(debug, uint, 0644);
 256 MODULE_PARM_DESC(debug, "CPUfreq debugging: add 1 to debug core,"
 257                         " 2 to debug drivers, and 4 to debug governors.");
 258
 259 module_param(debug_ratelimit, uint, 0644);
 260 MODULE_PARM_DESC(debug_ratelimit, "CPUfreq debugging:"
 261                                         " set to 0 to disable ratelimiting.");
 262
 263 #else /* !CONFIG_CPU_FREQ_DEBUG */
 264
 265 static inline void cpufreq_debug_enable_ratelimit(void) { return; }
 266 static inline void cpufreq_debug_disable_ratelimit(void) { return; }
 267
 268 #endif /* CONFIG_CPU_FREQ_DEBUG */
 269
 270
 271 /*********************************************************************
 272  *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
 273  *********************************************************************/
 274
 275 /**
 276  * adjust_jiffies - adjust the system "loops_per_jiffy"
 277  *
 278  * This function alters the system "loops_per_jiffy" for the clock
 279  * speed change. Note that loops_per_jiffy cannot be updated on SMP
 280  * systems as each CPU might be scaled differently. So, use the arch
 281  * per-CPU loops_per_jiffy value wherever possible.
 282  */
 283 #ifndef CONFIG_SMP
 284 static unsigned long l_p_j_ref;
 285 static unsigned int  l_p_j_ref_freq;
 286
 287 static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 288 {
 289         if (ci->flags & CPUFREQ_CONST_LOOPS)
 290                 return;
 291
 292         if (!l_p_j_ref_freq) {
 293                 l_p_j_ref = loops_per_jiffy;
 294                 l_p_j_ref_freq = ci->old;
 295                 dprintk("saving %lu as reference value for loops_per_jiffy; "
 296                         "freq is %u kHz\n", l_p_j_ref, l_p_j_ref_freq);
 297         }
 298         if ((val == CPUFREQ_PRECHANGE  && ci->old < ci->new) ||
 299             (val == CPUFREQ_POSTCHANGE && ci->old > ci->new) ||
 300             (val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE)) {
 301                 loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq,
 302                                                                 ci->new);
 303                 dprintk("scaling loops_per_jiffy to %lu "
 304                         "for frequency %u kHz\n", loops_per_jiffy, ci->new);
 305         }
 306 }
 307 #else
 308 static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 309 {
 310         return;
 311 }
 312 #endif
 313
 314
 315 /**
 316  * cpufreq_notify_transition - call notifier chain and adjust_jiffies
 317  * on frequency transition.
 318  *
 319  * This function calls the transition notifiers and the "adjust_jiffies"
 320  * function. It is called twice on all CPU frequency changes that have
 321  * external effects.
 322  */
 323 void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
 324 {
 325         struct cpufreq_policy *policy;
 326
 327         BUG_ON(irqs_disabled());
 328
 329         freqs->flags = cpufreq_driver->flags;
 330         dprintk("notification %u of frequency transition to %u kHz\n",
 331                 state, freqs->new);
 332
 333         policy = per_cpu(cpufreq_cpu_data, freqs->cpu);
 334         switch (state) {
 335
 336         case CPUFREQ_PRECHANGE:
 337                 /* detect if the driver reported a value as "old frequency"
 338                  * which is not equal to what the cpufreq core thinks is
 339                  * "old frequency".
 340                  */
 341                 if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
 342                         if ((policy) && (policy->cpu == freqs->cpu) &&
 343                             (policy->cur) && (policy->cur != freqs->old)) {
 344                                 dprintk("Warning: CPU frequency is"
 345                                         " %u, cpufreq assumed %u kHz.\n",
 346                                         freqs->old, policy->cur);
 347                                 freqs->old = policy->cur;
 348                         }
 349                 }
 350                 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
 351                                 CPUFREQ_PRECHANGE, freqs);
 352                 adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
 353                 break;
 354
 355         case CPUFREQ_POSTCHANGE:
 356                 adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
 357                 srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
 358                                 CPUFREQ_POSTCHANGE, freqs);
 359                 if (likely(policy) && likely(policy->cpu == freqs->cpu))
 360                         policy->cur = freqs->new;
 361                 break;
 362         }
 363 }
 364 EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
 365
 366
 367
 368 /*********************************************************************
 369  *                          SYSFS INTERFACE                          *
 370  *********************************************************************/
 371
 372 static struct cpufreq_governor *__find_governor(const char *str_governor)
 373 {
 374         struct cpufreq_governor *t;
 375
 376         list_for_each_entry(t, &cpufreq_governor_list, governor_list)
 377                 if (!strnicmp(str_governor, t->name, CPUFREQ_NAME_LEN))
 378                         return t;
 379
 380         return NULL;
 381 }
 382
 383 /**
 384  * cpufreq_parse_governor - parse a governor string
 385  */
 386 static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
 387                                 struct cpufreq_governor **governor)
 388 {
 389         int err = -EINVAL;
 390
 391         if (!cpufreq_driver)
 392                 goto out;
 393
 394         if (cpufreq_driver->setpolicy) {
 395                 if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
 396                         *policy = CPUFREQ_POLICY_PERFORMANCE;
 397                         err = 0;
 398                 } else if (!strnicmp(str_governor, "powersave",
 399                                                 CPUFREQ_NAME_LEN)) {
 400                         *policy = CPUFREQ_POLICY_POWERSAVE;
 401                         err = 0;
 402                 }
 403         } else if (cpufreq_driver->target) {
 404                 struct cpufreq_governor *t;
 405
 406                 mutex_lock(&cpufreq_governor_mutex);
 407
 408                 t = __find_governor(str_governor);
 409
 410                 if (t == NULL) {
 411                         char *name = kasprintf(GFP_KERNEL, "cpufreq_%s",
 412                                                                 str_governor);
 413
 414                         if (name) {
 415                                 int ret;
 416
 417                                 mutex_unlock(&cpufreq_governor_mutex);
 418                                 ret = request_module("%s", name);
 419                                 mutex_lock(&cpufreq_governor_mutex);
 420
 421                                 if (ret == 0)
 422                                         t = __find_governor(str_governor);
 423                         }
 424
 425                         kfree(name);
 426                 }
 427
 428                 if (t != NULL) {
 429                         *governor = t;
 430                         err = 0;
 431                 }
 432
 433                 mutex_unlock(&cpufreq_governor_mutex);
 434         }
 435 out:
 436         return err;
 437 }
 438
 439
 440 /**
 441  * cpufreq_per_cpu_attr_read() / show_##file_name() -
 442  * print out cpufreq information
 443  *
 444  * Write out information from cpufreq_driver->policy[cpu]; object must be
 445  * "unsigned int".
 446  */
 447
 448 #define show_one(file_name, object)                     \
 449 static ssize_t show_##file_name                         \
 450 (struct cpufreq_policy *policy, char *buf)              \
 451 {                                                       \
 452         return sprintf(buf, "%u\n", policy->object);    \
 453 }
 454
 455 show_one(cpuinfo_min_freq, cpuinfo.min_freq);
 456 show_one(cpuinfo_max_freq, cpuinfo.max_freq);
 457 show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
 458 show_one(scaling_min_freq, min);
 459 show_one(scaling_max_freq, max);
 460 show_one(scaling_cur_freq, cur);
 461
 462 static int __cpufreq_set_policy(struct cpufreq_policy *data,
 463                                 struct cpufreq_policy *policy);
 464
 465 /**
 466  * cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
 467  */
 468 #define store_one(file_name, object)                    \
 469 static ssize_t store_##file_name                                        \
 470 (struct cpufreq_policy *policy, const char *buf, size_t count)          \
 471 {                                                                       \
 472         unsigned int ret = -EINVAL;                                     \
 473         struct cpufreq_policy new_policy;                               \
 474                                                                         \
 475         ret = cpufreq_get_policy(&new_policy, policy->cpu);             \
 476         if (ret)                                                        \
 477                 return -EINVAL;                                         \
 478                                                                         \
 479         ret = sscanf(buf, "%u", &new_policy.object);                    \
 480         if (ret != 1)                                                   \
 481                 return -EINVAL;                                         \
 482                                                                         \
 483         ret = __cpufreq_set_policy(policy, &new_policy);                \
 484         policy->user_policy.object = policy->object;                    \
 485                                                                         \
 486         return ret ? ret : count;                                       \
 487 }
 488
 489 store_one(scaling_min_freq, min);
 490 store_one(scaling_max_freq, max);
 491
 492 /**
 493  * show_cpuinfo_cur_freq - current CPU frequency as detected by hardware
 494  */
 495 static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
 496                                         char *buf)
 497 {
 498         unsigned int cur_freq = __cpufreq_get(policy->cpu);
 499         if (!cur_freq)
 500                 return sprintf(buf, "<unknown>");
 501         return sprintf(buf, "%u\n", cur_freq);
 502 }
 503
 504
 505 /**
 506  * show_scaling_governor - show the current policy for the specified CPU
 507  */
 508 static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf)
 509 {
 510         if (policy->policy == CPUFREQ_POLICY_POWERSAVE)
 511                 return sprintf(buf, "powersave\n");
 512         else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
 513                 return sprintf(buf, "performance\n");
 514         else if (policy->governor)
 515                 return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n",
 516                                 policy->governor->name);
 517         return -EINVAL;
 518 }
 519
 520
 521 /**
 522  * store_scaling_governor - store policy for the specified CPU
 523  */
 524 static ssize_t store_scaling_governor(struct cpufreq_policy *policy,
 525                                         const char *buf, size_t count)
 526 {
 527         unsigned int ret = -EINVAL;
 528         char    str_governor[16];
 529         struct cpufreq_policy new_policy;
 530
 531         ret = cpufreq_get_policy(&new_policy, policy->cpu);
 532         if (ret)
 533                 return ret;
 534
 535         ret = sscanf(buf, "%15s", str_governor);
 536         if (ret != 1)
 537                 return -EINVAL;
 538
 539         if (cpufreq_parse_governor(str_governor, &new_policy.policy,
 540                                                 &new_policy.governor))
 541                 return -EINVAL;
 542
 543         /* Do not use cpufreq_set_policy here or the user_policy.max
 544            will be wrongly overridden */
 545         ret = __cpufreq_set_policy(policy, &new_policy);
 546
 547         policy->user_policy.policy = policy->policy;
 548         policy->user_policy.governor = policy->governor;
 549
 550         if (ret)
 551                 return ret;
 552         else
 553                 return count;
 554 }
 555
 556 /**
 557  * show_scaling_driver - show the cpufreq driver currently loaded
 558  */
 559 static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
 560 {
 561         return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n", cpufreq_driver->name);
 562 }
 563
 564 /**
 565  * show_scaling_available_governors - show the available CPUfreq governors
 566  */
 567 static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
 568                                                 char *buf)
 569 {
 570         ssize_t i = 0;
 571         struct cpufreq_governor *t;
 572
 573         if (!cpufreq_driver->target) {
 574                 i += sprintf(buf, "performance powersave");
 575                 goto out;
 576         }
 577
 578         list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
 579                 if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
 580                     - (CPUFREQ_NAME_LEN + 2)))
 581                         goto out;
 582                 i += scnprintf(&buf[i], CPUFREQ_NAME_LEN, "%s ", t->name);
 583         }
 584 out:
 585         i += sprintf(&buf[i], "\n");
 586         return i;
 587 }
 588
 589 static ssize_t show_cpus(const struct cpumask *mask, char *buf)
 590 {
 591         ssize_t i = 0;
 592         unsigned int cpu;
 593
 594         for_each_cpu(cpu, mask) {
 595                 if (i)
 596                         i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), " ");
 597                 i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u", cpu);
 598                 if (i >= (PAGE_SIZE - 5))
 599                         break;
 600         }
 601         i += sprintf(&buf[i], "\n");
 602         return i;
 603 }
 604
 605 /**
 606  * show_related_cpus - show the CPUs affected by each transition even if
 607  * hw coordination is in use
 608  */
 609 static ssize_t show_related_cpus(struct cpufreq_policy *policy, char *buf)
 610 {
 611         if (cpumask_empty(policy->related_cpus))
 612                 return show_cpus(policy->cpus, buf);
 613         return show_cpus(policy->related_cpus, buf);
 614 }
 615
 616 /**
 617  * show_affected_cpus - show the CPUs affected by each transition
 618  */
 619 static ssize_t show_affected_cpus(struct cpufreq_policy *policy, char *buf)
 620 {
 621         return show_cpus(policy->cpus, buf);
 622 }
 623
 624 static ssize_t store_scaling_setspeed(struct cpufreq_policy *policy,
 625                                         const char *buf, size_t count)
 626 {
 627         unsigned int freq = 0;
 628         unsigned int ret;
 629
 630         if (!policy->governor || !policy->governor->store_setspeed)
 631                 return -EINVAL;
 632
 633         ret = sscanf(buf, "%u", &freq);
 634         if (ret != 1)
 635                 return -EINVAL;
 636
 637         policy->governor->store_setspeed(policy, freq);
 638
 639         return count;
 640 }
 641
 642 static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
 643 {
 644         if (!policy->governor || !policy->governor->show_setspeed)
 645                 return sprintf(buf, "<unsupported>\n");
 646
 647         return policy->governor->show_setspeed(policy, buf);
 648 }
 649
 650 /**
 651  * show_scaling_driver - show the current cpufreq HW/BIOS limitation
 652  */
 653 static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
 654 {
 655         unsigned int limit;
 656         int ret;
 657         if (cpufreq_driver->bios_limit) {
 658                 ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
 659                 if (!ret)
 660                         return sprintf(buf, "%u\n", limit);
 661         }
 662         return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
 663 }
 664
 665 cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);
 666 cpufreq_freq_attr_ro(cpuinfo_min_freq);
 667 cpufreq_freq_attr_ro(cpuinfo_max_freq);
 668 cpufreq_freq_attr_ro(cpuinfo_transition_latency);
 669 cpufreq_freq_attr_ro(scaling_available_governors);
 670 cpufreq_freq_attr_ro(scaling_driver);
 671 cpufreq_freq_attr_ro(scaling_cur_freq);
 672 cpufreq_freq_attr_ro(bios_limit);
 673 cpufreq_freq_attr_ro(related_cpus);
 674 cpufreq_freq_attr_ro(affected_cpus);
 675 cpufreq_freq_attr_rw(scaling_min_freq);
 676 cpufreq_freq_attr_rw(scaling_max_freq);
 677 cpufreq_freq_attr_rw(scaling_governor);
 678 cpufreq_freq_attr_rw(scaling_setspeed);
 679
 680 static struct attribute *default_attrs[] = {
 681         &cpuinfo_min_freq.attr,
 682         &cpuinfo_max_freq.attr,
 683         &cpuinfo_transition_latency.attr,
 684         &scaling_min_freq.attr,
 685         &scaling_max_freq.attr,
 686         &affected_cpus.attr,
 687         &related_cpus.attr,
 688         &scaling_governor.attr,
 689         &scaling_driver.attr,
 690         &scaling_available_governors.attr,
 691         &scaling_setspeed.attr,
 692         NULL
 693 };
 694
 695 struct kobject *cpufreq_global_kobject;
 696 EXPORT_SYMBOL(cpufreq_global_kobject);
 697
 698 #define to_policy(k) container_of(k, struct cpufreq_policy, kobj)
 699 #define to_attr(a) container_of(a, struct freq_attr, attr)
 700
 701 static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
 702 {
 703         struct cpufreq_policy *policy = to_policy(kobj);
 704         struct freq_attr *fattr = to_attr(attr);
 705         ssize_t ret = -EINVAL;
 706         policy = cpufreq_cpu_get(policy->cpu);
 707         if (!policy)
 708                 goto no_policy;
 709
 710         if (lock_policy_rwsem_read(policy->cpu) < 0)
 711                 goto fail;
 712
 713         if (fattr->show)
 714                 ret = fattr->show(policy, buf);
 715         else
 716                 ret = -EIO;
 717
 718         unlock_policy_rwsem_read(policy->cpu);
 719 fail:
 720         cpufreq_cpu_put(policy);
 721 no_policy:
 722         return ret;
 723 }
 724
 725 static ssize_t store(struct kobject *kobj, struct attribute *attr,
 726                      const char *buf, size_t count)
 727 {
 728         struct cpufreq_policy *policy = to_policy(kobj);
 729         struct freq_attr *fattr = to_attr(attr);
 730         ssize_t ret = -EINVAL;
 731         policy = cpufreq_cpu_get(policy->cpu);
 732         if (!policy)
 733                 goto no_policy;
 734
 735         if (lock_policy_rwsem_write(policy->cpu) < 0)
 736                 goto fail;
 737
 738         if (fattr->store)
 739                 ret = fattr->store(policy, buf, count);
 740         else
 741                 ret = -EIO;
 742
 743         unlock_policy_rwsem_write(policy->cpu);
 744 fail:
 745         cpufreq_cpu_put(policy);
 746 no_policy:
 747         return ret;
 748 }
 749
 750 static void cpufreq_sysfs_release(struct kobject *kobj)
 751 {
 752         struct cpufreq_policy *policy = to_policy(kobj);
 753         dprintk("last reference is dropped\n");
 754         complete(&policy->kobj_unregister);
 755 }
 756
 757 static const struct sysfs_ops sysfs_ops = {
 758         .show   = show,
 759         .store  = store,
 760 };
 761
 762 static struct kobj_type ktype_cpufreq = {
 763         .sysfs_ops      = &sysfs_ops,
 764         .default_attrs  = default_attrs,
 765         .release        = cpufreq_sysfs_release,
 766 };
 767
 768 /*
 769  * Returns:
 770  *   Negative: Failure
 771  *   0:        Success
 772  *   Positive: When we have a managed CPU and the sysfs got symlinked
 773  */
 774 static int cpufreq_add_dev_policy(unsigned int cpu,
 775                                   struct cpufreq_policy *policy,
 776                                   struct sys_device *sys_dev)
 777 {
 778         int ret = 0;
 779 #ifdef CONFIG_SMP
 780         unsigned long flags;
 781         unsigned int j;
 782 #ifdef CONFIG_HOTPLUG_CPU
 783         struct cpufreq_governor *gov;
 784
 785         gov = __find_governor(per_cpu(cpufreq_cpu_governor, cpu));
 786         if (gov) {
 787                 policy->governor = gov;
 788                 dprintk("Restoring governor %s for cpu %d\n",
 789                        policy->governor->name, cpu);
 790         }
 791 #endif
 792
 793         for_each_cpu(j, policy->cpus) {
 794                 struct cpufreq_policy *managed_policy;
 795
 796                 if (cpu == j)
 797                         continue;
 798
 799                 /* Check for existing affected CPUs.
 800                  * They may not be aware of it due to CPU Hotplug.
 801                  * cpufreq_cpu_put is called when the device is removed
 802                  * in __cpufreq_remove_dev()
 803                  */
 804                 managed_policy = cpufreq_cpu_get(j);
 805                 if (unlikely(managed_policy)) {
 806
 807                         /* Set proper policy_cpu */
 808                         unlock_policy_rwsem_write(cpu);
 809                         per_cpu(cpufreq_policy_cpu, cpu) = managed_policy->cpu;
 810
 811                         if (lock_policy_rwsem_write(cpu) < 0) {
 812                                 /* Should not go through policy unlock path */
 813                                 if (cpufreq_driver->exit)
 814                                         cpufreq_driver->exit(policy);
 815                                 cpufreq_cpu_put(managed_policy);
 816                                 return -EBUSY;
 817                         }
 818
 819                         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 820                         cpumask_copy(managed_policy->cpus, policy->cpus);
 821                         per_cpu(cpufreq_cpu_data, cpu) = managed_policy;
 822                         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 823
 824                         dprintk("CPU already managed, adding link\n");
 825                         ret = sysfs_create_link(&sys_dev->kobj,
 826                                                 &managed_policy->kobj,
 827                                                 "cpufreq");
 828                         if (ret)
 829                                 cpufreq_cpu_put(managed_policy);
 830                         /*
 831                          * Success. We only needed to be added to the mask.
 832                          * Call driver->exit() because only the cpu parent of
 833                          * the kobj needed to call init().
 834                          */
 835                         if (cpufreq_driver->exit)
 836                                 cpufreq_driver->exit(policy);
 837
 838                         if (!ret)
 839                                 return 1;
 840                         else
 841                                 return ret;
 842                 }
 843         }
 844 #endif
 845         return ret;
 846 }
 847
 848
 849 /* symlink affected CPUs */
 850 static int cpufreq_add_dev_symlink(unsigned int cpu,
 851                                    struct cpufreq_policy *policy)
 852 {
 853         unsigned int j;
 854         int ret = 0;
 855
 856         for_each_cpu(j, policy->cpus) {
 857                 struct cpufreq_policy *managed_policy;
 858                 struct sys_device *cpu_sys_dev;
 859
 860                 if (j == cpu)
 861                         continue;
 862                 if (!cpu_online(j))
 863                         continue;
 864
 865                 dprintk("CPU %u already managed, adding link\n", j);
 866                 managed_policy = cpufreq_cpu_get(cpu);
 867                 cpu_sys_dev = get_cpu_sysdev(j);
 868                 ret = sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj,
 869                                         "cpufreq");
 870                 if (ret) {
 871                         cpufreq_cpu_put(managed_policy);
 872                         return ret;
 873                 }
 874         }
 875         return ret;
 876 }
 877
 878 static int cpufreq_add_dev_interface(unsigned int cpu,
 879                                      struct cpufreq_policy *policy,
 880                                      struct sys_device *sys_dev)
 881 {
 882         struct cpufreq_policy new_policy;
 883         struct freq_attr **drv_attr;
 884         unsigned long flags;
 885         int ret = 0;
 886         unsigned int j;
 887
 888         /* prepare interface data */
 889         ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
 890                                    &sys_dev->kobj, "cpufreq");
 891         if (ret)
 892                 return ret;
 893
 894         /* set up files for this cpu device */
 895         drv_attr = cpufreq_driver->attr;
 896         while ((drv_attr) && (*drv_attr)) {
 897                 ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
 898                 if (ret)
 899                         goto err_out_kobj_put;
 900                 drv_attr++;
 901         }
 902         if (cpufreq_driver->get) {
 903                 ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
 904                 if (ret)
 905                         goto err_out_kobj_put;
 906         }
 907         if (cpufreq_driver->target) {
 908                 ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
 909                 if (ret)
 910                         goto err_out_kobj_put;
 911         }
 912         if (cpufreq_driver->bios_limit) {
 913                 ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
 914                 if (ret)
 915                         goto err_out_kobj_put;
 916         }
 917
 918         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 919         for_each_cpu(j, policy->cpus) {
 920         if (!cpu_online(j))
 921                 continue;
 922                 per_cpu(cpufreq_cpu_data, j) = policy;
 923                 per_cpu(cpufreq_policy_cpu, j) = policy->cpu;
 924         }
 925         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 926
 927         ret = cpufreq_add_dev_symlink(cpu, policy);
 928         if (ret)
 929                 goto err_out_kobj_put;
 930
 931         memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
 932         /* assure that the starting sequence is run in __cpufreq_set_policy */
 933         policy->governor = NULL;
 934
 935         /* set default policy */
 936         ret = __cpufreq_set_policy(policy, &new_policy);
 937         policy->user_policy.policy = policy->policy;
 938         policy->user_policy.governor = policy->governor;
 939
 940         if (ret) {
 941                 dprintk("setting policy failed\n");
 942                 if (cpufreq_driver->exit)
 943                         cpufreq_driver->exit(policy);
 944         }
 945         return ret;
 946
 947 err_out_kobj_put:
 948         kobject_put(&policy->kobj);
 949         wait_for_completion(&policy->kobj_unregister);
 950         return ret;
 951 }
 952
 953
 954 /**
 955  * cpufreq_add_dev - add a CPU device
 956  *
 957  * Adds the cpufreq interface for a CPU device.
 958  *
 959  * The Oracle says: try running cpufreq registration/unregistration concurrently
 960  * with with cpu hotplugging and all hell will break loose. Tried to clean this
 961  * mess up, but more thorough testing is needed. - Mathieu
 962  */
 963 static int cpufreq_add_dev(struct sys_device *sys_dev)
 964 {
 965         unsigned int cpu = sys_dev->id;
 966         int ret = 0, found = 0;
 967         struct cpufreq_policy *policy;
 968         unsigned long flags;
 969         unsigned int j;
 970 #ifdef CONFIG_HOTPLUG_CPU
 971         int sibling;
 972 #endif
 973
 974         if (cpu_is_offline(cpu))
 975                 return 0;
 976
 977         cpufreq_debug_disable_ratelimit();
 978         dprintk("adding CPU %u\n", cpu);
 979
 980 #ifdef CONFIG_SMP
 981         /* check whether a different CPU already registered this
 982          * CPU because it is in the same boat. */
 983         policy = cpufreq_cpu_get(cpu);
 984         if (unlikely(policy)) {
 985                 cpufreq_cpu_put(policy);
 986                 cpufreq_debug_enable_ratelimit();
 987                 return 0;
 988         }
 989 #endif
 990
 991         if (!try_module_get(cpufreq_driver->owner)) {
 992                 ret = -EINVAL;
 993                 goto module_out;
 994         }
 995
 996         ret = -ENOMEM;
 997         policy = kzalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
 998         if (!policy)
 999                 goto nomem_out;
1000
1001         if (!alloc_cpumask_var(&policy->cpus, GFP_KERNEL))
1002                 goto err_free_policy;
1003
1004         if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL))
1005                 goto err_free_cpumask;
1006
1007         policy->cpu = cpu;
1008         cpumask_copy(policy->cpus, cpumask_of(cpu));
1009
1010         /* Initially set CPU itself as the policy_cpu */
1011         per_cpu(cpufreq_policy_cpu, cpu) = cpu;
1012         ret = (lock_policy_rwsem_write(cpu) < 0);
1013         WARN_ON(ret);
1014
1015         init_completion(&policy->kobj_unregister);
1016         INIT_WORK(&policy->update, handle_update);
1017
1018         /* Set governor before ->init, so that driver could check it */
1019 #ifdef CONFIG_HOTPLUG_CPU
1020         for_each_online_cpu(sibling) {
1021                 struct cpufreq_policy *cp = per_cpu(cpufreq_cpu_data, sibling);
1022                 if (cp && cp->governor &&
1023                     (cpumask_test_cpu(cpu, cp->related_cpus))) {
1024                         policy->governor = cp->governor;
1025                         found = 1;
1026                         break;
1027                 }
1028         }
1029 #endif
1030         if (!found)
1031                 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
1032         /* call driver. From then on the cpufreq must be able
1033          * to accept all calls to ->verify and ->setpolicy for this CPU
1034          */
1035         ret = cpufreq_driver->init(policy);
1036         if (ret) {
1037                 dprintk("initialization failed\n");
1038                 goto err_unlock_policy;
1039         }
1040         policy->user_policy.min = policy->min;
1041         policy->user_policy.max = policy->max;
1042
1043         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1044                                      CPUFREQ_START, policy);
1045
1046         ret = cpufreq_add_dev_policy(cpu, policy, sys_dev);
1047         if (ret) {
1048                 if (ret > 0)
1049                         /* This is a managed cpu, symlink created,
1050                            exit with 0 */
1051                         ret = 0;
1052                 goto err_unlock_policy;
1053         }
1054
1055         ret = cpufreq_add_dev_interface(cpu, policy, sys_dev);
1056         if (ret)
1057                 goto err_out_unregister;
1058
1059         unlock_policy_rwsem_write(cpu);
1060
1061         kobject_uevent(&policy->kobj, KOBJ_ADD);
1062         module_put(cpufreq_driver->owner);
1063         dprintk("initialization complete\n");
1064         cpufreq_debug_enable_ratelimit();
1065
1066         return 0;
1067
1068
1069 err_out_unregister:
1070         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1071         for_each_cpu(j, policy->cpus)
1072                 per_cpu(cpufreq_cpu_data, j) = NULL;
1073         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1074
1075         kobject_put(&policy->kobj);
1076         wait_for_completion(&policy->kobj_unregister);
1077
1078 err_unlock_policy:
1079         unlock_policy_rwsem_write(cpu);
1080 err_free_cpumask:
1081         free_cpumask_var(policy->cpus);
1082 err_free_policy:
1083         kfree(policy);
1084 nomem_out:
1085         module_put(cpufreq_driver->owner);
1086 module_out:
1087         cpufreq_debug_enable_ratelimit();
1088         return ret;
1089 }
1090
1091
1092 /**
1093  * __cpufreq_remove_dev - remove a CPU device
1094  *
1095  * Removes the cpufreq interface for a CPU device.
1096  * Caller should already have policy_rwsem in write mode for this CPU.
1097  * This routine frees the rwsem before returning.
1098  */
1099 static int __cpufreq_remove_dev(struct sys_device *sys_dev)
1100 {
1101         unsigned int cpu = sys_dev->id;
1102         unsigned long flags;
1103         struct cpufreq_policy *data;
1104         struct kobject *kobj;
1105         struct completion *cmp;
1106 #ifdef CONFIG_SMP
1107         struct sys_device *cpu_sys_dev;
1108         unsigned int j;
1109 #endif
1110
1111         cpufreq_debug_disable_ratelimit();
1112         dprintk("unregistering CPU %u\n", cpu);
1113
1114         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1115         data = per_cpu(cpufreq_cpu_data, cpu);
1116
1117         if (!data) {
1118                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1119                 cpufreq_debug_enable_ratelimit();
1120                 unlock_policy_rwsem_write(cpu);
1121                 return -EINVAL;
1122         }
1123         per_cpu(cpufreq_cpu_data, cpu) = NULL;
1124
1125
1126 #ifdef CONFIG_SMP
1127         /* if this isn't the CPU which is the parent of the kobj, we
1128          * only need to unlink, put and exit
1129          */
1130         if (unlikely(cpu != data->cpu)) {
1131                 dprintk("removing link\n");
1132                 cpumask_clear_cpu(cpu, data->cpus);
1133                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1134                 kobj = &sys_dev->kobj;
1135                 cpufreq_cpu_put(data);
1136                 cpufreq_debug_enable_ratelimit();
1137                 unlock_policy_rwsem_write(cpu);
1138                 sysfs_remove_link(kobj, "cpufreq");
1139                 return 0;
1140         }
1141 #endif
1142
1143 #ifdef CONFIG_SMP
1144
1145 #ifdef CONFIG_HOTPLUG_CPU
1146         strncpy(per_cpu(cpufreq_cpu_governor, cpu), data->governor->name,
1147                         CPUFREQ_NAME_LEN);
1148 #endif
1149
1150         /* if we have other CPUs still registered, we need to unlink them,
1151          * or else wait_for_completion below will lock up. Clean the
1152          * per_cpu(cpufreq_cpu_data) while holding the lock, and remove
1153          * the sysfs links afterwards.
1154          */
1155         if (unlikely(cpumask_weight(data->cpus) > 1)) {
1156                 for_each_cpu(j, data->cpus) {
1157                         if (j == cpu)
1158                                 continue;
1159                         per_cpu(cpufreq_cpu_data, j) = NULL;
1160                 }
1161         }
1162
1163         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1164
1165         if (unlikely(cpumask_weight(data->cpus) > 1)) {
1166                 for_each_cpu(j, data->cpus) {
1167                         if (j == cpu)
1168                                 continue;
1169                         dprintk("removing link for cpu %u\n", j);
1170 #ifdef CONFIG_HOTPLUG_CPU
1171                         strncpy(per_cpu(cpufreq_cpu_governor, j),
1172                                 data->governor->name, CPUFREQ_NAME_LEN);
1173 #endif
1174                         cpu_sys_dev = get_cpu_sysdev(j);
1175                         kobj = &cpu_sys_dev->kobj;
1176                         unlock_policy_rwsem_write(cpu);
1177                         sysfs_remove_link(kobj, "cpufreq");
1178                         lock_policy_rwsem_write(cpu);
1179                         cpufreq_cpu_put(data);
1180                 }
1181         }
1182 #else
1183         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1184 #endif
1185
1186         if (cpufreq_driver->target)
1187                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
1188
1189         kobj = &data->kobj;
1190         cmp = &data->kobj_unregister;
1191         unlock_policy_rwsem_write(cpu);
1192         kobject_put(kobj);
1193
1194         /* we need to make sure that the underlying kobj is actually
1195          * not referenced anymore by anybody before we proceed with
1196          * unloading.
1197          */
1198         dprintk("waiting for dropping of refcount\n");
1199         wait_for_completion(cmp);
1200         dprintk("wait complete\n");
1201
1202         lock_policy_rwsem_write(cpu);
1203         if (cpufreq_driver->exit)
1204                 cpufreq_driver->exit(data);
1205         unlock_policy_rwsem_write(cpu);
1206
1207         free_cpumask_var(data->related_cpus);
1208         free_cpumask_var(data->cpus);
1209         kfree(data);
1210         per_cpu(cpufreq_cpu_data, cpu) = NULL;
1211
1212         cpufreq_debug_enable_ratelimit();
1213         return 0;
1214 }
1215
1216
1217 static int cpufreq_remove_dev(struct sys_device *sys_dev)
1218 {
1219         unsigned int cpu = sys_dev->id;
1220         int retval;
1221
1222         if (cpu_is_offline(cpu))
1223                 return 0;
1224
1225         if (unlikely(lock_policy_rwsem_write(cpu)))
1226                 BUG();
1227
1228         retval = __cpufreq_remove_dev(sys_dev);
1229         return retval;
1230 }
1231
1232
1233 static void handle_update(struct work_struct *work)
1234 {
1235         struct cpufreq_policy *policy =
1236                 container_of(work, struct cpufreq_policy, update);
1237         unsigned int cpu = policy->cpu;
1238         dprintk("handle_update for cpu %u called\n", cpu);
1239         cpufreq_update_policy(cpu);
1240 }
1241
1242 /**
1243  *      cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're in deep trouble.
1244  *      @cpu: cpu number
1245  *      @old_freq: CPU frequency the kernel thinks the CPU runs at
1246  *      @new_freq: CPU frequency the CPU actually runs at
1247  *
1248  *      We adjust to current frequency first, and need to clean up later.
1249  *      So either call to cpufreq_update_policy() or schedule handle_update()).
1250  */
1251 static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq,
1252                                 unsigned int new_freq)
1253 {
1254         struct cpufreq_freqs freqs;
1255
1256         dprintk("Warning: CPU frequency out of sync: cpufreq and timing "
1257                "core thinks of %u, is %u kHz.\n", old_freq, new_freq);
1258
1259         freqs.cpu = cpu;
1260         freqs.old = old_freq;
1261         freqs.new = new_freq;
1262         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
1263         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
1264 }
1265
1266
1267 /**
1268  * cpufreq_quick_get - get the CPU frequency (in kHz) from policy->cur
1269  * @cpu: CPU number
1270  *
1271  * This is the last known freq, without actually getting it from the driver.
1272  * Return value will be same as what is shown in scaling_cur_freq in sysfs.
1273  */
1274 unsigned int cpufreq_quick_get(unsigned int cpu)
1275 {
1276         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
1277         unsigned int ret_freq = 0;
1278
1279         if (policy) {
1280                 ret_freq = policy->cur;
1281                 cpufreq_cpu_put(policy);
1282         }
1283
1284         return ret_freq;
1285 }
1286 EXPORT_SYMBOL(cpufreq_quick_get);
1287
1288
1289 static unsigned int __cpufreq_get(unsigned int cpu)
1290 {
1291         struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
1292         unsigned int ret_freq = 0;
1293
1294         if (!cpufreq_driver->get)
1295                 return ret_freq;
1296
1297         ret_freq = cpufreq_driver->get(cpu);
1298
1299         if (ret_freq && policy->cur &&
1300                 !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
1301                 /* verify no discrepancy between actual and
1302                                         saved value exists */
1303                 if (unlikely(ret_freq != policy->cur)) {
1304                         cpufreq_out_of_sync(cpu, policy->cur, ret_freq);
1305                         schedule_work(&policy->update);
1306                 }
1307         }
1308
1309         return ret_freq;
1310 }
1311
1312 /**
1313  * cpufreq_get - get the current CPU frequency (in kHz)
1314  * @cpu: CPU number
1315  *
1316  * Get the CPU current (static) CPU frequency
1317  */
1318 unsigned int cpufreq_get(unsigned int cpu)
1319 {
1320         unsigned int ret_freq = 0;
1321         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
1322
1323         if (!policy)
1324                 goto out;
1325
1326         if (unlikely(lock_policy_rwsem_read(cpu)))
1327                 goto out_policy;
1328
1329         ret_freq = __cpufreq_get(cpu);
1330
1331         unlock_policy_rwsem_read(cpu);
1332
1333 out_policy:
1334         cpufreq_cpu_put(policy);
1335 out:
1336         return ret_freq;
1337 }
1338 EXPORT_SYMBOL(cpufreq_get);
1339
1340
1341 /**
1342  *      cpufreq_suspend - let the low level driver prepare for suspend
1343  */
1344
1345 static int cpufreq_suspend(struct sys_device *sysdev, pm_message_t pmsg)
1346 {
1347         int ret = 0;
1348
1349         int cpu = sysdev->id;
1350         struct cpufreq_policy *cpu_policy;
1351
1352         dprintk("suspending cpu %u\n", cpu);
1353
1354         if (!cpu_online(cpu))
1355                 return 0;
1356
1357         /* we may be lax here as interrupts are off. Nonetheless
1358          * we need to grab the correct cpu policy, as to check
1359          * whether we really run on this CPU.
1360          */
1361
1362         cpu_policy = cpufreq_cpu_get(cpu);
1363         if (!cpu_policy)
1364                 return -EINVAL;
1365
1366         /* only handle each CPU group once */
1367         if (unlikely(cpu_policy->cpu != cpu))
1368                 goto out;
1369
1370         if (cpufreq_driver->suspend) {
1371                 ret = cpufreq_driver->suspend(cpu_policy, pmsg);
1372                 if (ret)
1373                         printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
1374                                         "step on CPU %u\n", cpu_policy->cpu);
1375         }
1376
1377 out:
1378         cpufreq_cpu_put(cpu_policy);
1379         return ret;
1380 }
1381
1382 /**
1383  *      cpufreq_resume -  restore proper CPU frequency handling after resume
1384  *
1385  *      1.) resume CPUfreq hardware support (cpufreq_driver->resume())
1386  *      2.) schedule call cpufreq_update_policy() ASAP as interrupts are
1387  *          restored. It will verify that the current freq is in sync with
1388  *          what we believe it to be. This is a bit later than when it
1389  *          should be, but nonethteless it's better than calling
1390  *          cpufreq_driver->get() here which might re-enable interrupts...
1391  */
1392 static int cpufreq_resume(struct sys_device *sysdev)
1393 {
1394         int ret = 0;
1395
1396         int cpu = sysdev->id;
1397         struct cpufreq_policy *cpu_policy;
1398
1399         dprintk("resuming cpu %u\n", cpu);
1400
1401         if (!cpu_online(cpu))
1402                 return 0;
1403
1404         /* we may be lax here as interrupts are off. Nonetheless
1405          * we need to grab the correct cpu policy, as to check
1406          * whether we really run on this CPU.
1407          */
1408
1409         cpu_policy = cpufreq_cpu_get(cpu);
1410         if (!cpu_policy)
1411                 return -EINVAL;
1412
1413         /* only handle each CPU group once */
1414         if (unlikely(cpu_policy->cpu != cpu))
1415                 goto fail;
1416
1417         if (cpufreq_driver->resume) {
1418                 ret = cpufreq_driver->resume(cpu_policy);
1419                 if (ret) {
1420                         printk(KERN_ERR "cpufreq: resume failed in ->resume "
1421                                         "step on CPU %u\n", cpu_policy->cpu);
1422                         goto fail;
1423                 }
1424         }
1425
1426         schedule_work(&cpu_policy->update);
1427
1428 fail:
1429         cpufreq_cpu_put(cpu_policy);
1430         return ret;
1431 }
1432
1433 static struct sysdev_driver cpufreq_sysdev_driver = {
1434         .add            = cpufreq_add_dev,
1435         .remove         = cpufreq_remove_dev,
1436         .suspend        = cpufreq_suspend,
1437         .resume         = cpufreq_resume,
1438 };
1439
1440
1441 /*********************************************************************
1442  *                     NOTIFIER LISTS INTERFACE                      *
1443  *********************************************************************/
1444
1445 /**
1446  *      cpufreq_register_notifier - register a driver with cpufreq
1447  *      @nb: notifier function to register
1448  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
1449  *
1450  *      Add a driver to one of two lists: either a list of drivers that
1451  *      are notified about clock rate changes (once before and once after
1452  *      the transition), or a list of drivers that are notified about
1453  *      changes in cpufreq policy.
1454  *
1455  *      This function may sleep, and has the same return conditions as
1456  *      blocking_notifier_chain_register.
1457  */
1458 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
1459 {
1460         int ret;
1461
1462         WARN_ON(!init_cpufreq_transition_notifier_list_called);
1463
1464         switch (list) {
1465         case CPUFREQ_TRANSITION_NOTIFIER:
1466                 ret = srcu_notifier_chain_register(
1467                                 &cpufreq_transition_notifier_list, nb);
1468                 break;
1469         case CPUFREQ_POLICY_NOTIFIER:
1470                 ret = blocking_notifier_chain_register(
1471                                 &cpufreq_policy_notifier_list, nb);
1472                 break;
1473         default:
1474                 ret = -EINVAL;
1475         }
1476
1477         return ret;
1478 }
1479 EXPORT_SYMBOL(cpufreq_register_notifier);
1480
1481
1482 /**
1483  *      cpufreq_unregister_notifier - unregister a driver with cpufreq
1484  *      @nb: notifier block to be unregistered
1485  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
1486  *
1487  *      Remove a driver from the CPU frequency notifier list.
1488  *
1489  *      This function may sleep, and has the same return conditions as
1490  *      blocking_notifier_chain_unregister.
1491  */
1492 int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
1493 {
1494         int ret;
1495
1496         switch (list) {
1497         case CPUFREQ_TRANSITION_NOTIFIER:
1498                 ret = srcu_notifier_chain_unregister(
1499                                 &cpufreq_transition_notifier_list, nb);
1500                 break;
1501         case CPUFREQ_POLICY_NOTIFIER:
1502                 ret = blocking_notifier_chain_unregister(
1503                                 &cpufreq_policy_notifier_list, nb);
1504                 break;
1505         default:
1506                 ret = -EINVAL;
1507         }
1508
1509         return ret;
1510 }
1511 EXPORT_SYMBOL(cpufreq_unregister_notifier);
1512
1513
1514 /*********************************************************************
1515  *                              GOVERNORS                            *
1516  *********************************************************************/
1517
1518
1519 int __cpufreq_driver_target(struct cpufreq_policy *policy,
1520                             unsigned int target_freq,
1521                             unsigned int relation)
1522 {
1523         int retval = -EINVAL;
1524
1525         dprintk("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
1526                 target_freq, relation);
1527         if (cpu_online(policy->cpu) && cpufreq_driver->target)
1528                 retval = cpufreq_driver->target(policy, target_freq, relation);
1529
1530         return retval;
1531 }
1532 EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
1533
1534 int cpufreq_driver_target(struct cpufreq_policy *policy,
1535                           unsigned int target_freq,
1536                           unsigned int relation)
1537 {
1538         int ret = -EINVAL;
1539
1540         policy = cpufreq_cpu_get(policy->cpu);
1541         if (!policy)
1542                 goto no_policy;
1543
1544         if (unlikely(lock_policy_rwsem_write(policy->cpu)))
1545                 goto fail;
1546
1547         ret = __cpufreq_driver_target(policy, target_freq, relation);
1548
1549         unlock_policy_rwsem_write(policy->cpu);
1550
1551 fail:
1552         cpufreq_cpu_put(policy);
1553 no_policy:
1554         return ret;
1555 }
1556 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
1557
1558 int __cpufreq_driver_getavg(struct cpufreq_policy *policy, unsigned int cpu)
1559 {
1560         int ret = 0;
1561
1562         policy = cpufreq_cpu_get(policy->cpu);
1563         if (!policy)
1564                 return -EINVAL;
1565
1566         if (cpu_online(cpu) && cpufreq_driver->getavg)
1567                 ret = cpufreq_driver->getavg(policy, cpu);
1568
1569         cpufreq_cpu_put(policy);
1570         return ret;
1571 }
1572 EXPORT_SYMBOL_GPL(__cpufreq_driver_getavg);
1573
1574 /*
1575  * when "event" is CPUFREQ_GOV_LIMITS
1576  */
1577
1578 static int __cpufreq_governor(struct cpufreq_policy *policy,
1579                                         unsigned int event)
1580 {
1581         int ret;
1582
1583         /* Only must be defined when default governor is known to have latency
1584            restrictions, like e.g. conservative or ondemand.
1585            That this is the case is already ensured in Kconfig
1586         */
1587 #ifdef CONFIG_CPU_FREQ_GOV_PERFORMANCE
1588         struct cpufreq_governor *gov = &cpufreq_gov_performance;
1589 #else
1590         struct cpufreq_governor *gov = NULL;
1591 #endif
1592
1593         if (policy->governor->max_transition_latency &&
1594             policy->cpuinfo.transition_latency >
1595             policy->governor->max_transition_latency) {
1596                 if (!gov)
1597                         return -EINVAL;
1598                 else {
1599                         printk(KERN_WARNING "%s governor failed, too long"
1600                                " transition latency of HW, fallback"
1601                                " to %s governor\n",
1602                                policy->governor->name,
1603                                gov->name);
1604                         policy->governor = gov;
1605                 }
1606         }
1607
1608         if (!try_module_get(policy->governor->owner))
1609                 return -EINVAL;
1610
1611         dprintk("__cpufreq_governor for CPU %u, event %u\n",
1612                                                 policy->cpu, event);
1613         ret = policy->governor->governor(policy, event);
1614
1615         /* we keep one module reference alive for
1616                         each CPU governed by this CPU */
1617         if ((event != CPUFREQ_GOV_START) || ret)
1618                 module_put(policy->governor->owner);
1619         if ((event == CPUFREQ_GOV_STOP) && !ret)
1620                 module_put(policy->governor->owner);
1621
1622         return ret;
1623 }
1624
1625
1626 int cpufreq_register_governor(struct cpufreq_governor *governor)
1627 {
1628         int err;
1629
1630         if (!governor)
1631                 return -EINVAL;
1632
1633         mutex_lock(&cpufreq_governor_mutex);
1634
1635         err = -EBUSY;
1636         if (__find_governor(governor->name) == NULL) {
1637                 err = 0;
1638                 list_add(&governor->governor_list, &cpufreq_governor_list);
1639         }
1640
1641         mutex_unlock(&cpufreq_governor_mutex);
1642         return err;
1643 }
1644 EXPORT_SYMBOL_GPL(cpufreq_register_governor);
1645
1646
1647 void cpufreq_unregister_governor(struct cpufreq_governor *governor)
1648 {
1649 #ifdef CONFIG_HOTPLUG_CPU
1650         int cpu;
1651 #endif
1652
1653         if (!governor)
1654                 return;
1655
1656 #ifdef CONFIG_HOTPLUG_CPU
1657         for_each_present_cpu(cpu) {
1658                 if (cpu_online(cpu))
1659                         continue;
1660                 if (!strcmp(per_cpu(cpufreq_cpu_governor, cpu), governor->name))
1661                         strcpy(per_cpu(cpufreq_cpu_governor, cpu), "\0");
1662         }
1663 #endif
1664
1665         mutex_lock(&cpufreq_governor_mutex);
1666         list_del(&governor->governor_list);
1667         mutex_unlock(&cpufreq_governor_mutex);
1668         return;
1669 }
1670 EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
1671
1672
1673
1674 /*********************************************************************
1675  *                          POLICY INTERFACE                         *
1676  *********************************************************************/
1677
1678 /**
1679  * cpufreq_get_policy - get the current cpufreq_policy
1680  * @policy: struct cpufreq_policy into which the current cpufreq_policy
1681  *      is written
1682  *
1683  * Reads the current cpufreq policy.
1684  */
1685 int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
1686 {
1687         struct cpufreq_policy *cpu_policy;
1688         if (!policy)
1689                 return -EINVAL;
1690
1691         cpu_policy = cpufreq_cpu_get(cpu);
1692         if (!cpu_policy)
1693                 return -EINVAL;
1694
1695         memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
1696
1697         cpufreq_cpu_put(cpu_policy);
1698         return 0;
1699 }
1700 EXPORT_SYMBOL(cpufreq_get_policy);
1701
1702
1703 /*
1704  * data   : current policy.
1705  * policy : policy to be set.
1706  */
1707 static int __cpufreq_set_policy(struct cpufreq_policy *data,
1708                                 struct cpufreq_policy *policy)
1709 {
1710         int ret = 0;
1711
1712         cpufreq_debug_disable_ratelimit();
1713         dprintk("setting new policy for CPU %u: %u - %u kHz\n", policy->cpu,
1714                 policy->min, policy->max);
1715
1716         memcpy(&policy->cpuinfo, &data->cpuinfo,
1717                                 sizeof(struct cpufreq_cpuinfo));
1718
1719         if (policy->min > data->max || policy->max < data->min) {
1720                 ret = -EINVAL;
1721                 goto error_out;
1722         }
1723
1724         /* verify the cpu speed can be set within this limit */
1725         ret = cpufreq_driver->verify(policy);
1726         if (ret)
1727                 goto error_out;
1728
1729         /* adjust if necessary - all reasons */
1730         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1731                         CPUFREQ_ADJUST, policy);
1732
1733         /* adjust if necessary - hardware incompatibility*/
1734         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1735                         CPUFREQ_INCOMPATIBLE, policy);
1736
1737         /* verify the cpu speed can be set within this limit,
1738            which might be different to the first one */
1739         ret = cpufreq_driver->verify(policy);
1740         if (ret)
1741                 goto error_out;
1742
1743         /* notification of the new policy */
1744         blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
1745                         CPUFREQ_NOTIFY, policy);
1746
1747         data->min = policy->min;
1748         data->max = policy->max;
1749
1750         dprintk("new min and max freqs are %u - %u kHz\n",
1751                                         data->min, data->max);
1752
1753         if (cpufreq_driver->setpolicy) {
1754                 data->policy = policy->policy;
1755                 dprintk("setting range\n");
1756                 ret = cpufreq_driver->setpolicy(policy);
1757         } else {
1758                 if (policy->governor != data->governor) {
1759                         /* save old, working values */
1760                         struct cpufreq_governor *old_gov = data->governor;
1761
1762                         dprintk("governor switch\n");
1763
1764                         /* end old governor */
1765                         if (data->governor) {
1766                                 /*
1767                                  * Need to release the rwsem around governor
1768                                  * stop due to lock dependency between
1769                                  * cancel_delayed_work_sync and the read lock
1770                                  * taken in the delayed work handler.
1771                                  */
1772                                 unlock_policy_rwsem_write(data->cpu);
1773                                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
1774                                 lock_policy_rwsem_write(data->cpu);
1775                         }
1776
1777                         /* start new governor */
1778                         data->governor = policy->governor;
1779                         if (__cpufreq_governor(data, CPUFREQ_GOV_START)) {
1780                                 /* new governor failed, so re-start old one */
1781                                 dprintk("starting governor %s failed\n",
1782                                                         data->governor->name);
1783                                 if (old_gov) {
1784                                         data->governor = old_gov;
1785                                         __cpufreq_governor(data,
1786                                                            CPUFREQ_GOV_START);
1787                                 }
1788                                 ret = -EINVAL;
1789                                 goto error_out;
1790                         }
1791                         /* might be a policy change, too, so fall through */
1792                 }
1793                 dprintk("governor: change or update limits\n");
1794                 __cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
1795         }
1796
1797 error_out:
1798         cpufreq_debug_enable_ratelimit();
1799         return ret;
1800 }
1801
1802 /**
1803  *      cpufreq_update_policy - re-evaluate an existing cpufreq policy
1804  *      @cpu: CPU which shall be re-evaluated
1805  *
1806  *      Usefull for policy notifiers which have different necessities
1807  *      at different times.
1808  */
1809 int cpufreq_update_policy(unsigned int cpu)
1810 {
1811         struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
1812         struct cpufreq_policy policy;
1813         int ret;
1814
1815         if (!data) {
1816                 ret = -ENODEV;
1817                 goto no_policy;
1818         }
1819
1820         if (unlikely(lock_policy_rwsem_write(cpu))) {
1821                 ret = -EINVAL;
1822                 goto fail;
1823         }
1824
1825         dprintk("updating policy for CPU %u\n", cpu);
1826         memcpy(&policy, data, sizeof(struct cpufreq_policy));
1827         policy.min = data->user_policy.min;
1828         policy.max = data->user_policy.max;
1829         policy.policy = data->user_policy.policy;
1830         policy.governor = data->user_policy.governor;
1831
1832         /* BIOS might change freq behind our back
1833           -> ask driver for current freq and notify governors about a change */
1834         if (cpufreq_driver->get) {
1835                 policy.cur = cpufreq_driver->get(cpu);
1836                 if (!data->cur) {
1837                         dprintk("Driver did not initialize current freq");
1838                         data->cur = policy.cur;
1839                 } else {
1840                         if (data->cur != policy.cur)
1841                                 cpufreq_out_of_sync(cpu, data->cur,
1842                                                                 policy.cur);
1843                 }
1844         }
1845
1846         ret = __cpufreq_set_policy(data, &policy);
1847
1848         unlock_policy_rwsem_write(cpu);
1849
1850 fail:
1851         cpufreq_cpu_put(data);
1852 no_policy:
1853         return ret;
1854 }
1855 EXPORT_SYMBOL(cpufreq_update_policy);
1856
1857 static int __cpuinit cpufreq_cpu_callback(struct notifier_block *nfb,
1858                                         unsigned long action, void *hcpu)
1859 {
1860         unsigned int cpu = (unsigned long)hcpu;
1861         struct sys_device *sys_dev;
1862
1863         sys_dev = get_cpu_sysdev(cpu);
1864         if (sys_dev) {
1865                 switch (action) {
1866                 case CPU_ONLINE:
1867                 case CPU_ONLINE_FROZEN:
1868                         cpufreq_add_dev(sys_dev);
1869                         break;
1870                 case CPU_DOWN_PREPARE:
1871                 case CPU_DOWN_PREPARE_FROZEN:
1872                         if (unlikely(lock_policy_rwsem_write(cpu)))
1873                                 BUG();
1874
1875                         __cpufreq_remove_dev(sys_dev);
1876                         break;
1877                 case CPU_DOWN_FAILED:
1878                 case CPU_DOWN_FAILED_FROZEN:
1879                         cpufreq_add_dev(sys_dev);
1880                         break;
1881                 }
1882         }
1883         return NOTIFY_OK;
1884 }
1885
1886 static struct notifier_block __refdata cpufreq_cpu_notifier =
1887 {
1888     .notifier_call = cpufreq_cpu_callback,
1889 };
1890
1891 /*********************************************************************
1892  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
1893  *********************************************************************/
1894
1895 /**
1896  * cpufreq_register_driver - register a CPU Frequency driver
1897  * @driver_data: A struct cpufreq_driver containing the values#
1898  * submitted by the CPU Frequency driver.
1899  *
1900  *   Registers a CPU Frequency driver to this core code. This code
1901  * returns zero on success, -EBUSY when another driver got here first
1902  * (and isn't unregistered in the meantime).
1903  *
1904  */
1905 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
1906 {
1907         unsigned long flags;
1908         int ret;
1909
1910         if (!driver_data || !driver_data->verify || !driver_data->init ||
1911             ((!driver_data->setpolicy) && (!driver_data->target)))
1912                 return -EINVAL;
1913
1914         dprintk("trying to register driver %s\n", driver_data->name);
1915
1916         if (driver_data->setpolicy)
1917                 driver_data->flags |= CPUFREQ_CONST_LOOPS;
1918
1919         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1920         if (cpufreq_driver) {
1921                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1922                 return -EBUSY;
1923         }
1924         cpufreq_driver = driver_data;
1925         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1926
1927         ret = sysdev_driver_register(&cpu_sysdev_class,
1928                                         &cpufreq_sysdev_driver);
1929
1930         if ((!ret) && !(cpufreq_driver->flags & CPUFREQ_STICKY)) {
1931                 int i;
1932                 ret = -ENODEV;
1933
1934                 /* check for at least one working CPU */
1935                 for (i = 0; i < nr_cpu_ids; i++)
1936                         if (cpu_possible(i) && per_cpu(cpufreq_cpu_data, i)) {
1937                                 ret = 0;
1938                                 break;
1939                         }
1940
1941                 /* if all ->init() calls failed, unregister */
1942                 if (ret) {
1943                         dprintk("no CPU initialized for driver %s\n",
1944                                                         driver_data->name);
1945                         sysdev_driver_unregister(&cpu_sysdev_class,
1946                                                 &cpufreq_sysdev_driver);
1947
1948                         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1949                         cpufreq_driver = NULL;
1950                         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1951                 }
1952         }
1953
1954         if (!ret) {
1955                 register_hotcpu_notifier(&cpufreq_cpu_notifier);
1956                 dprintk("driver %s up and running\n", driver_data->name);
1957                 cpufreq_debug_enable_ratelimit();
1958         }
1959
1960         return ret;
1961 }
1962 EXPORT_SYMBOL_GPL(cpufreq_register_driver);
1963
1964
1965 /**
1966  * cpufreq_unregister_driver - unregister the current CPUFreq driver
1967  *
1968  *    Unregister the current CPUFreq driver. Only call this if you have
1969  * the right to do so, i.e. if you have succeeded in initialising before!
1970  * Returns zero if successful, and -EINVAL if the cpufreq_driver is
1971  * currently not initialised.
1972  */
1973 int cpufreq_unregister_driver(struct cpufreq_driver *driver)
1974 {
1975         unsigned long flags;
1976
1977         cpufreq_debug_disable_ratelimit();
1978
1979         if (!cpufreq_driver || (driver != cpufreq_driver)) {
1980                 cpufreq_debug_enable_ratelimit();
1981                 return -EINVAL;
1982         }
1983
1984         dprintk("unregistering driver %s\n", driver->name);
1985
1986         sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
1987         unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
1988
1989         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1990         cpufreq_driver = NULL;
1991         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1992
1993         return 0;
1994 }
1995 EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
1996
1997 static int __init cpufreq_core_init(void)
1998 {
1999         int cpu;
2000
2001         for_each_possible_cpu(cpu) {
2002                 per_cpu(cpufreq_policy_cpu, cpu) = -1;
2003                 init_rwsem(&per_cpu(cpu_policy_rwsem, cpu));
2004         }
2005
2006         cpufreq_global_kobject = kobject_create_and_add("cpufreq",
2007                                                 &cpu_sysdev_class.kset.kobj);
2008         BUG_ON(!cpufreq_global_kobject);
2009
2010         return 0;
2011 }
2012 core_initcall(cpufreq_core_init);