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  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  */
  12
  13 #include <linux/config.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/init.h>
  17 #include <linux/notifier.h>
  18 #include <linux/cpufreq.h>
  19 #include <linux/delay.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/device.h>
  23 #include <linux/slab.h>
  24 #include <linux/cpu.h>
  25 #include <linux/completion.h>
  26
  27 /**
  28  * The "cpufreq driver" - the arch- or hardware-dependend low
  29  * level driver of CPUFreq support, and its spinlock. This lock
  30  * also protects the cpufreq_cpu_data array.
  31  */
  32 static struct cpufreq_driver    *cpufreq_driver;
  33 static struct cpufreq_policy    *cpufreq_cpu_data[NR_CPUS];
  34 static spinlock_t               cpufreq_driver_lock = SPIN_LOCK_UNLOCKED;
  35
  36 /* internal prototypes */
  37 static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event);
  38 static void handle_update(void *data);
  39 static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci);
  40
  41 /**
  42  * Two notifier lists: the "policy" list is involved in the
  43  * validation process for a new CPU frequency policy; the
  44  * "transition" list for kernel code that needs to handle
  45  * changes to devices when the CPU clock speed changes.
  46  * The mutex locks both lists.
  47  */
  48 static struct notifier_block    *cpufreq_policy_notifier_list;
  49 static struct notifier_block    *cpufreq_transition_notifier_list;
  50 static DECLARE_RWSEM            (cpufreq_notifier_rwsem);
  51
  52
  53 static LIST_HEAD(cpufreq_governor_list);
  54 static DECLARE_MUTEX            (cpufreq_governor_sem);
  55
  56 static struct cpufreq_policy * cpufreq_cpu_get(unsigned int cpu)
  57 {
  58         struct cpufreq_policy *data;
  59         unsigned long flags;
  60
  61         if (cpu >= NR_CPUS)
  62                 goto err_out;
  63
  64         /* get the cpufreq driver */
  65         spin_lock_irqsave(&cpufreq_driver_lock, flags);
  66
  67         if (!cpufreq_driver)
  68                 goto err_out_unlock;
  69
  70         if (!try_module_get(cpufreq_driver->owner))
  71                 goto err_out_unlock;
  72
  73
  74         /* get the CPU */
  75         data = cpufreq_cpu_data[cpu];
  76
  77         if (!data)
  78                 goto err_out_put_module;
  79
  80         if (!kobject_get(&data->kobj))
  81                 goto err_out_put_module;
  82
  83
  84         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
  85
  86         return data;
  87
  88  err_out_put_module:
  89         module_put(cpufreq_driver->owner);
  90  err_out_unlock:
  91         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
  92  err_out:
  93         return NULL;
  94 }
  95
  96 static void cpufreq_cpu_put(struct cpufreq_policy *data)
  97 {
  98         kobject_put(&data->kobj);
  99         module_put(cpufreq_driver->owner);
 100 }
 101
 102 /*********************************************************************
 103  *                          SYSFS INTERFACE                          *
 104  *********************************************************************/
 105
 106 /**
 107  * cpufreq_parse_governor - parse a governor string
 108  */
 109 int cpufreq_parse_governor (char *str_governor, unsigned int *policy,
 110                                 struct cpufreq_governor **governor)
 111 {
 112         if (!cpufreq_driver)
 113                 return -EINVAL;
 114         if (cpufreq_driver->setpolicy) {
 115                 if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
 116                         *policy = CPUFREQ_POLICY_PERFORMANCE;
 117                         return 0;
 118                 } else if (!strnicmp(str_governor, "powersave", CPUFREQ_NAME_LEN)) {
 119                         *policy = CPUFREQ_POLICY_POWERSAVE;
 120                         return 0;
 121                 }
 122                 return -EINVAL;
 123         } else {
 124                 struct cpufreq_governor *t;
 125                 down(&cpufreq_governor_sem);
 126                 if (!cpufreq_driver || !cpufreq_driver->target)
 127                         goto out;
 128                 list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
 129                         if (!strnicmp(str_governor,t->name,CPUFREQ_NAME_LEN)) {
 130                                 *governor = t;
 131                                 up(&cpufreq_governor_sem);
 132                                 return 0;
 133                         }
 134                 }
 135         out:
 136                 up(&cpufreq_governor_sem);
 137         }
 138         return -EINVAL;
 139 }
 140 EXPORT_SYMBOL_GPL(cpufreq_parse_governor);
 141
 142
 143 /* drivers/base/cpu.c */
 144 extern struct sysdev_class cpu_sysdev_class;
 145
 146
 147 /**
 148  * cpufreq_per_cpu_attr_read() / show_##file_name() - print out cpufreq information
 149  *
 150  * Write out information from cpufreq_driver->policy[cpu]; object must be
 151  * "unsigned int".
 152  */
 153
 154 #define show_one(file_name, object)                                     \
 155 static ssize_t show_##file_name                                         \
 156 (struct cpufreq_policy * policy, char *buf)                             \
 157 {                                                                       \
 158         return sprintf (buf, "%u\n", policy->object);                   \
 159 }
 160
 161 show_one(cpuinfo_min_freq, cpuinfo.min_freq);
 162 show_one(cpuinfo_max_freq, cpuinfo.max_freq);
 163 show_one(scaling_min_freq, min);
 164 show_one(scaling_max_freq, max);
 165 show_one(scaling_cur_freq, cur);
 166
 167 /**
 168  * cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
 169  */
 170 #define store_one(file_name, object)                    \
 171 static ssize_t store_##file_name                                        \
 172 (struct cpufreq_policy * policy, const char *buf, size_t count)         \
 173 {                                                                       \
 174         unsigned int ret = -EINVAL;                                     \
 175         struct cpufreq_policy new_policy;                               \
 176                                                                         \
 177         ret = cpufreq_get_policy(&new_policy, policy->cpu);             \
 178         if (ret)                                                        \
 179                 return -EINVAL;                                         \
 180                                                                         \
 181         ret = sscanf (buf, "%u", &new_policy.object);                   \
 182         if (ret != 1)                                                   \
 183                 return -EINVAL;                                         \
 184                                                                         \
 185         ret = cpufreq_set_policy(&new_policy);                          \
 186                                                                         \
 187         return ret ? ret : count;                                       \
 188 }
 189
 190 store_one(scaling_min_freq,min);
 191 store_one(scaling_max_freq,max);
 192
 193 /**
 194  * show_cpuinfo_cur_freq - current CPU frequency as detected by hardware
 195  */
 196 static ssize_t show_cpuinfo_cur_freq (struct cpufreq_policy * policy, char *buf)
 197 {
 198         unsigned int cur_freq = cpufreq_get(policy->cpu);
 199         if (!cur_freq)
 200                 return sprintf(buf, "<unknown>");
 201         return sprintf(buf, "%u\n", cur_freq);
 202 }
 203
 204
 205 /**
 206  * show_scaling_governor - show the current policy for the specified CPU
 207  */
 208 static ssize_t show_scaling_governor (struct cpufreq_policy * policy, char *buf)
 209 {
 210         if(policy->policy == CPUFREQ_POLICY_POWERSAVE)
 211                 return sprintf(buf, "powersave\n");
 212         else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
 213                 return sprintf(buf, "performance\n");
 214         else if (policy->governor)
 215                 return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n", policy->governor->name);
 216         return -EINVAL;
 217 }
 218
 219
 220 /**
 221  * store_scaling_governor - store policy for the specified CPU
 222  */
 223 static ssize_t store_scaling_governor (struct cpufreq_policy * policy,
 224                                        const char *buf, size_t count)
 225 {
 226         unsigned int ret = -EINVAL;
 227         char    str_governor[16];
 228         struct cpufreq_policy new_policy;
 229
 230         ret = cpufreq_get_policy(&new_policy, policy->cpu);
 231         if (ret)
 232                 return ret;
 233
 234         ret = sscanf (buf, "%15s", str_governor);
 235         if (ret != 1)
 236                 return -EINVAL;
 237
 238         if (cpufreq_parse_governor(str_governor, &new_policy.policy, &new_policy.governor))
 239                 return -EINVAL;
 240
 241         ret = cpufreq_set_policy(&new_policy);
 242
 243         return ret ? ret : count;
 244 }
 245
 246 /**
 247  * show_scaling_driver - show the cpufreq driver currently loaded
 248  */
 249 static ssize_t show_scaling_driver (struct cpufreq_policy * policy, char *buf)
 250 {
 251         return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n", cpufreq_driver->name);
 252 }
 253
 254 /**
 255  * show_scaling_available_governors - show the available CPUfreq governors
 256  */
 257 static ssize_t show_scaling_available_governors (struct cpufreq_policy * policy,
 258                                 char *buf)
 259 {
 260         ssize_t i = 0;
 261         struct cpufreq_governor *t;
 262
 263         if (!cpufreq_driver->target) {
 264                 i += sprintf(buf, "performance powersave");
 265                 goto out;
 266         }
 267
 268         list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
 269                 if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char)) - (CPUFREQ_NAME_LEN + 2)))
 270                         goto out;
 271                 i += scnprintf(&buf[i], CPUFREQ_NAME_LEN, "%s ", t->name);
 272         }
 273  out:
 274         i += sprintf(&buf[i], "\n");
 275         return i;
 276 }
 277
 278
 279 #define define_one_ro(_name) \
 280 struct freq_attr _name = { \
 281         .attr = { .name = __stringify(_name), .mode = 0444 }, \
 282         .show = show_##_name, \
 283 }
 284
 285 #define define_one_ro0400(_name) \
 286 struct freq_attr _name = { \
 287         .attr = { .name = __stringify(_name), .mode = 0400 }, \
 288         .show = show_##_name, \
 289 }
 290
 291 #define define_one_rw(_name) \
 292 struct freq_attr _name = { \
 293         .attr = { .name = __stringify(_name), .mode = 0644 }, \
 294         .show = show_##_name, \
 295         .store = store_##_name, \
 296 }
 297
 298 define_one_ro0400(cpuinfo_cur_freq);
 299 define_one_ro(cpuinfo_min_freq);
 300 define_one_ro(cpuinfo_max_freq);
 301 define_one_ro(scaling_available_governors);
 302 define_one_ro(scaling_driver);
 303 define_one_ro(scaling_cur_freq);
 304 define_one_rw(scaling_min_freq);
 305 define_one_rw(scaling_max_freq);
 306 define_one_rw(scaling_governor);
 307
 308 static struct attribute * default_attrs[] = {
 309         &cpuinfo_min_freq.attr,
 310         &cpuinfo_max_freq.attr,
 311         &scaling_min_freq.attr,
 312         &scaling_max_freq.attr,
 313         &scaling_governor.attr,
 314         &scaling_driver.attr,
 315         &scaling_available_governors.attr,
 316         NULL
 317 };
 318
 319 #define to_policy(k) container_of(k,struct cpufreq_policy,kobj)
 320 #define to_attr(a) container_of(a,struct freq_attr,attr)
 321
 322 static ssize_t show(struct kobject * kobj, struct attribute * attr ,char * buf)
 323 {
 324         struct cpufreq_policy * policy = to_policy(kobj);
 325         struct freq_attr * fattr = to_attr(attr);
 326         ssize_t ret;
 327         policy = cpufreq_cpu_get(policy->cpu);
 328         if (!policy)
 329                 return -EINVAL;
 330         ret = fattr->show ? fattr->show(policy,buf) : 0;
 331         cpufreq_cpu_put(policy);
 332         return ret;
 333 }
 334
 335 static ssize_t store(struct kobject * kobj, struct attribute * attr,
 336                      const char * buf, size_t count)
 337 {
 338         struct cpufreq_policy * policy = to_policy(kobj);
 339         struct freq_attr * fattr = to_attr(attr);
 340         ssize_t ret;
 341         policy = cpufreq_cpu_get(policy->cpu);
 342         if (!policy)
 343                 return -EINVAL;
 344         ret = fattr->store ? fattr->store(policy,buf,count) : 0;
 345         cpufreq_cpu_put(policy);
 346         return ret;
 347 }
 348
 349 static void cpufreq_sysfs_release(struct kobject * kobj)
 350 {
 351         struct cpufreq_policy * policy = to_policy(kobj);
 352         complete(&policy->kobj_unregister);
 353 }
 354
 355 static struct sysfs_ops sysfs_ops = {
 356         .show   = show,
 357         .store  = store,
 358 };
 359
 360 static struct kobj_type ktype_cpufreq = {
 361         .sysfs_ops      = &sysfs_ops,
 362         .default_attrs  = default_attrs,
 363         .release        = cpufreq_sysfs_release,
 364 };
 365
 366
 367 /**
 368  * cpufreq_add_dev - add a CPU device
 369  *
 370  * Adds the cpufreq interface for a CPU device.
 371  */
 372 static int cpufreq_add_dev (struct sys_device * sys_dev)
 373 {
 374         unsigned int cpu = sys_dev->id;
 375         int ret = 0;
 376         struct cpufreq_policy new_policy;
 377         struct cpufreq_policy *policy;
 378         struct freq_attr **drv_attr;
 379         unsigned long flags;
 380
 381         if (!try_module_get(cpufreq_driver->owner))
 382                 return -EINVAL;
 383
 384         policy = kmalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
 385         if (!policy) {
 386                 ret = -ENOMEM;
 387                 goto nomem_out;
 388         }
 389         memset(policy, 0, sizeof(struct cpufreq_policy));
 390
 391         policy->cpu = cpu;
 392         init_MUTEX_LOCKED(&policy->lock);
 393         init_completion(&policy->kobj_unregister);
 394         INIT_WORK(&policy->update, handle_update, (void *)(long)cpu);
 395
 396         /* call driver. From then on the cpufreq must be able
 397          * to accept all calls to ->verify and ->setpolicy for this CPU
 398          */
 399         ret = cpufreq_driver->init(policy);
 400         if (ret)
 401                 goto err_out;
 402
 403         memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
 404
 405         /* prepare interface data */
 406         policy->kobj.parent = &sys_dev->kobj;
 407         policy->kobj.ktype = &ktype_cpufreq;
 408         strlcpy(policy->kobj.name, "cpufreq", KOBJ_NAME_LEN);
 409
 410         ret = kobject_register(&policy->kobj);
 411         if (ret)
 412                 goto err_out;
 413
 414         /* set up files for this cpu device */
 415         drv_attr = cpufreq_driver->attr;
 416         while ((drv_attr) && (*drv_attr)) {
 417                 sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
 418                 drv_attr++;
 419         }
 420         if (cpufreq_driver->get)
 421                 sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
 422         if (cpufreq_driver->target)
 423                 sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
 424
 425         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 426         cpufreq_cpu_data[cpu] = policy;
 427         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 428         policy->governor = NULL; /* to assure that the starting sequence is
 429                                   * run in cpufreq_set_policy */
 430         up(&policy->lock);
 431
 432         /* set default policy */
 433
 434         ret = cpufreq_set_policy(&new_policy);
 435         if (ret)
 436                 goto err_out_unregister;
 437
 438         module_put(cpufreq_driver->owner);
 439         return 0;
 440
 441
 442 err_out_unregister:
 443         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 444         cpufreq_cpu_data[cpu] = NULL;
 445         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 446
 447         kobject_unregister(&policy->kobj);
 448         wait_for_completion(&policy->kobj_unregister);
 449
 450 err_out:
 451         kfree(policy);
 452
 453 nomem_out:
 454         module_put(cpufreq_driver->owner);
 455         return ret;
 456 }
 457
 458
 459 /**
 460  * cpufreq_remove_dev - remove a CPU device
 461  *
 462  * Removes the cpufreq interface for a CPU device.
 463  */
 464 static int cpufreq_remove_dev (struct sys_device * sys_dev)
 465 {
 466         unsigned int cpu = sys_dev->id;
 467         unsigned long flags;
 468         struct cpufreq_policy *data;
 469
 470         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 471         data = cpufreq_cpu_data[cpu];
 472
 473         if (!data) {
 474                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 475                 return -EINVAL;
 476         }
 477         cpufreq_cpu_data[cpu] = NULL;
 478         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 479
 480         if (!kobject_get(&data->kobj))
 481                 return -EFAULT;
 482
 483         if (cpufreq_driver->target)
 484                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
 485
 486         kobject_unregister(&data->kobj);
 487
 488         kobject_put(&data->kobj);
 489
 490         /* we need to make sure that the underlying kobj is actually
 491          * not referenced anymore by anybody before we proceed with
 492          * unloading.
 493          */
 494         wait_for_completion(&data->kobj_unregister);
 495
 496         if (cpufreq_driver->exit)
 497                 cpufreq_driver->exit(data);
 498
 499         kfree(data);
 500
 501         return 0;
 502 }
 503
 504
 505 static void handle_update(void *data)
 506 {
 507         unsigned int cpu = (unsigned int)(long)data;
 508         cpufreq_update_policy(cpu);
 509 }
 510
 511 /**
 512  *      cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're in deep trouble.
 513  *      @cpu: cpu number
 514  *      @old_freq: CPU frequency the kernel thinks the CPU runs at
 515  *      @new_freq: CPU frequency the CPU actually runs at
 516  *
 517  *      We adjust to current frequency first, and need to clean up later. So either call
 518  *      to cpufreq_update_policy() or schedule handle_update()).
 519  */
 520 static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq, unsigned int new_freq)
 521 {
 522         struct cpufreq_freqs freqs;
 523
 524         if (cpufreq_driver->flags & CPUFREQ_PANIC_OUTOFSYNC)
 525                 panic("CPU Frequency is out of sync.");
 526
 527         printk(KERN_WARNING "Warning: CPU frequency out of sync: cpufreq and timing "
 528                "core thinks of %u, is %u kHz.\n", old_freq, new_freq);
 529
 530         freqs.cpu = cpu;
 531         freqs.old = old_freq;
 532         freqs.new = new_freq;
 533         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 534         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 535 }
 536
 537
 538 /**
 539  * cpufreq_get - get the current CPU frequency (in kHz)
 540  * @cpu: CPU number
 541  *
 542  * Get the CPU current (static) CPU frequency
 543  */
 544 unsigned int cpufreq_get(unsigned int cpu)
 545 {
 546         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
 547         unsigned int ret = 0;
 548
 549         if (!policy)
 550                 return 0;
 551
 552         if (!cpufreq_driver->get)
 553                 goto out;
 554
 555         down(&policy->lock);
 556
 557         ret = cpufreq_driver->get(cpu);
 558
 559         if (ret && policy->cur && !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS))
 560         {
 561                 /* verify no discrepancy between actual and saved value exists */
 562                 if (unlikely(ret != policy->cur)) {
 563                         cpufreq_out_of_sync(cpu, policy->cur, ret);
 564                         schedule_work(&policy->update);
 565                 }
 566         }
 567
 568         up(&policy->lock);
 569
 570  out:
 571         cpufreq_cpu_put(policy);
 572
 573         return (ret);
 574 }
 575 EXPORT_SYMBOL(cpufreq_get);
 576
 577
 578 /**
 579  *      cpufreq_resume -  restore proper CPU frequency handling after resume
 580  *
 581  *      1.) resume CPUfreq hardware support (cpufreq_driver->resume())
 582  *      2.) if ->target and !CPUFREQ_CONST_LOOPS: verify we're in sync
 583  *      3.) schedule call cpufreq_update_policy() ASAP as interrupts are restored.
 584  */
 585 static int cpufreq_resume(struct sys_device * sysdev)
 586 {
 587         int cpu = sysdev->id;
 588         unsigned int ret = 0;
 589         struct cpufreq_policy *cpu_policy;
 590
 591         if (!cpu_online(cpu))
 592                 return 0;
 593
 594         /* we may be lax here as interrupts are off. Nonetheless
 595          * we need to grab the correct cpu policy, as to check
 596          * whether we really run on this CPU.
 597          */
 598
 599         cpu_policy = cpufreq_cpu_get(cpu);
 600         if (!cpu_policy)
 601                 return -EINVAL;
 602
 603         if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
 604                 unsigned int cur_freq = 0;
 605
 606                 if (cpufreq_driver->get)
 607                         cur_freq = cpufreq_driver->get(cpu_policy->cpu);
 608
 609                 if (!cur_freq || !cpu_policy->cur) {
 610                         printk(KERN_ERR "cpufreq: resume failed to assert current frequency is what timing core thinks it is.\n");
 611                         goto out;
 612                 }
 613
 614                 if (unlikely(cur_freq != cpu_policy->cur)) {
 615                         struct cpufreq_freqs freqs;
 616
 617                         if (cpufreq_driver->flags & CPUFREQ_PANIC_RESUME_OUTOFSYNC)
 618                                 panic("CPU Frequency is out of sync.");
 619
 620                         printk(KERN_WARNING "Warning: CPU frequency out of sync: cpufreq and timing"
 621                                "core thinks of %u, is %u kHz.\n", cpu_policy->cur, cur_freq);
 622
 623                         freqs.cpu = cpu;
 624                         freqs.old = cpu_policy->cur;
 625                         freqs.new = cur_freq;
 626
 627                         notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_RESUMECHANGE, &freqs);
 628                         adjust_jiffies(CPUFREQ_RESUMECHANGE, &freqs);
 629                 }
 630         }
 631
 632 out:
 633         schedule_work(&cpu_policy->update);
 634         cpufreq_cpu_put(cpu_policy);
 635         return ret;
 636 }
 637
 638 static struct sysdev_driver cpufreq_sysdev_driver = {
 639         .add            = cpufreq_add_dev,
 640         .remove         = cpufreq_remove_dev,
 641         .resume         = cpufreq_resume,
 642 };
 643
 644
 645 /*********************************************************************
 646  *                     NOTIFIER LISTS INTERFACE                      *
 647  *********************************************************************/
 648
 649 /**
 650  *      cpufreq_register_notifier - register a driver with cpufreq
 651  *      @nb: notifier function to register
 652  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
 653  *
 654  *      Add a driver to one of two lists: either a list of drivers that
 655  *      are notified about clock rate changes (once before and once after
 656  *      the transition), or a list of drivers that are notified about
 657  *      changes in cpufreq policy.
 658  *
 659  *      This function may sleep, and has the same return conditions as
 660  *      notifier_chain_register.
 661  */
 662 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
 663 {
 664         int ret;
 665
 666         down_write(&cpufreq_notifier_rwsem);
 667         switch (list) {
 668         case CPUFREQ_TRANSITION_NOTIFIER:
 669                 ret = notifier_chain_register(&cpufreq_transition_notifier_list, nb);
 670                 break;
 671         case CPUFREQ_POLICY_NOTIFIER:
 672                 ret = notifier_chain_register(&cpufreq_policy_notifier_list, nb);
 673                 break;
 674         default:
 675                 ret = -EINVAL;
 676         }
 677         up_write(&cpufreq_notifier_rwsem);
 678
 679         return ret;
 680 }
 681 EXPORT_SYMBOL(cpufreq_register_notifier);
 682
 683
 684 /**
 685  *      cpufreq_unregister_notifier - unregister a driver with cpufreq
 686  *      @nb: notifier block to be unregistered
 687  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
 688  *
 689  *      Remove a driver from the CPU frequency notifier list.
 690  *
 691  *      This function may sleep, and has the same return conditions as
 692  *      notifier_chain_unregister.
 693  */
 694 int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
 695 {
 696         int ret;
 697
 698         down_write(&cpufreq_notifier_rwsem);
 699         switch (list) {
 700         case CPUFREQ_TRANSITION_NOTIFIER:
 701                 ret = notifier_chain_unregister(&cpufreq_transition_notifier_list, nb);
 702                 break;
 703         case CPUFREQ_POLICY_NOTIFIER:
 704                 ret = notifier_chain_unregister(&cpufreq_policy_notifier_list, nb);
 705                 break;
 706         default:
 707                 ret = -EINVAL;
 708         }
 709         up_write(&cpufreq_notifier_rwsem);
 710
 711         return ret;
 712 }
 713 EXPORT_SYMBOL(cpufreq_unregister_notifier);
 714
 715
 716 /*********************************************************************
 717  *                              GOVERNORS                            *
 718  *********************************************************************/
 719
 720
 721 int __cpufreq_driver_target(struct cpufreq_policy *policy,
 722                             unsigned int target_freq,
 723                             unsigned int relation)
 724 {
 725         int retval = -EINVAL;
 726         lock_cpu_hotplug();
 727         if (cpu_online(policy->cpu))
 728                 retval = cpufreq_driver->target(policy, target_freq, relation);
 729         unlock_cpu_hotplug();
 730         return retval;
 731 }
 732 EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
 733
 734
 735 int cpufreq_driver_target(struct cpufreq_policy *policy,
 736                           unsigned int target_freq,
 737                           unsigned int relation)
 738 {
 739         unsigned int ret;
 740
 741         policy = cpufreq_cpu_get(policy->cpu);
 742         if (!policy)
 743                 return -EINVAL;
 744
 745         down(&policy->lock);
 746
 747         ret = __cpufreq_driver_target(policy, target_freq, relation);
 748
 749         up(&policy->lock);
 750
 751         cpufreq_cpu_put(policy);
 752
 753         return ret;
 754 }
 755 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
 756
 757
 758 static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event)
 759 {
 760         int ret = -EINVAL;
 761
 762         if (!try_module_get(policy->governor->owner))
 763                 return -EINVAL;
 764
 765         ret = policy->governor->governor(policy, event);
 766
 767         /* we keep one module reference alive for each CPU governed by this CPU */
 768         if ((event != CPUFREQ_GOV_START) || ret)
 769                 module_put(policy->governor->owner);
 770         if ((event == CPUFREQ_GOV_STOP) && !ret)
 771                 module_put(policy->governor->owner);
 772
 773         return ret;
 774 }
 775
 776
 777 int cpufreq_governor(unsigned int cpu, unsigned int event)
 778 {
 779         int ret = 0;
 780         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
 781
 782         if (!policy)
 783                 return -EINVAL;
 784
 785         down(&policy->lock);
 786         ret = __cpufreq_governor(policy, event);
 787         up(&policy->lock);
 788
 789         cpufreq_cpu_put(policy);
 790
 791         return ret;
 792 }
 793 EXPORT_SYMBOL_GPL(cpufreq_governor);
 794
 795
 796 int cpufreq_register_governor(struct cpufreq_governor *governor)
 797 {
 798         struct cpufreq_governor *t;
 799
 800         if (!governor)
 801                 return -EINVAL;
 802
 803         down(&cpufreq_governor_sem);
 804
 805         list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
 806                 if (!strnicmp(governor->name,t->name,CPUFREQ_NAME_LEN)) {
 807                         up(&cpufreq_governor_sem);
 808                         return -EBUSY;
 809                 }
 810         }
 811         list_add(&governor->governor_list, &cpufreq_governor_list);
 812
 813         up(&cpufreq_governor_sem);
 814
 815         return 0;
 816 }
 817 EXPORT_SYMBOL_GPL(cpufreq_register_governor);
 818
 819
 820 void cpufreq_unregister_governor(struct cpufreq_governor *governor)
 821 {
 822         if (!governor)
 823                 return;
 824
 825         down(&cpufreq_governor_sem);
 826         list_del(&governor->governor_list);
 827         up(&cpufreq_governor_sem);
 828         return;
 829 }
 830 EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
 831
 832
 833
 834 /*********************************************************************
 835  *                          POLICY INTERFACE                         *
 836  *********************************************************************/
 837
 838 /**
 839  * cpufreq_get_policy - get the current cpufreq_policy
 840  * @policy: struct cpufreq_policy into which the current cpufreq_policy is written
 841  *
 842  * Reads the current cpufreq policy.
 843  */
 844 int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
 845 {
 846         struct cpufreq_policy *cpu_policy;
 847         if (!policy)
 848                 return -EINVAL;
 849
 850         cpu_policy = cpufreq_cpu_get(cpu);
 851         if (!cpu_policy)
 852                 return -EINVAL;
 853
 854         down(&cpu_policy->lock);
 855         memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
 856         up(&cpu_policy->lock);
 857
 858         cpufreq_cpu_put(cpu_policy);
 859
 860         return 0;
 861 }
 862 EXPORT_SYMBOL(cpufreq_get_policy);
 863
 864
 865 static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_policy *policy)
 866 {
 867         int ret = 0;
 868
 869         memcpy(&policy->cpuinfo,
 870                &data->cpuinfo,
 871                sizeof(struct cpufreq_cpuinfo));
 872
 873         /* verify the cpu speed can be set within this limit */
 874         ret = cpufreq_driver->verify(policy);
 875         if (ret)
 876                 goto error_out;
 877
 878         down_read(&cpufreq_notifier_rwsem);
 879
 880         /* adjust if necessary - all reasons */
 881         notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_ADJUST,
 882                             policy);
 883
 884         /* adjust if necessary - hardware incompatibility*/
 885         notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_INCOMPATIBLE,
 886                             policy);
 887
 888         /* verify the cpu speed can be set within this limit,
 889            which might be different to the first one */
 890         ret = cpufreq_driver->verify(policy);
 891         if (ret) {
 892                 up_read(&cpufreq_notifier_rwsem);
 893                 goto error_out;
 894         }
 895
 896         /* notification of the new policy */
 897         notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY,
 898                             policy);
 899
 900         up_read(&cpufreq_notifier_rwsem);
 901
 902         data->min    = policy->min;
 903         data->max    = policy->max;
 904
 905         if (cpufreq_driver->setpolicy) {
 906                 data->policy = policy->policy;
 907                 ret = cpufreq_driver->setpolicy(policy);
 908         } else {
 909                 if (policy->governor != data->governor) {
 910                         /* save old, working values */
 911                         struct cpufreq_governor *old_gov = data->governor;
 912
 913                         /* end old governor */
 914                         if (data->governor)
 915                                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
 916
 917                         /* start new governor */
 918                         data->governor = policy->governor;
 919                         if (__cpufreq_governor(data, CPUFREQ_GOV_START)) {
 920                                 /* new governor failed, so re-start old one */
 921                                 if (old_gov) {
 922                                         data->governor = old_gov;
 923                                         __cpufreq_governor(data, CPUFREQ_GOV_START);
 924                                 }
 925                                 ret = -EINVAL;
 926                                 goto error_out;
 927                         }
 928                         /* might be a policy change, too, so fall through */
 929                 }
 930                 __cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
 931         }
 932
 933  error_out:
 934         return ret;
 935 }
 936
 937 /**
 938  *      cpufreq_set_policy - set a new CPUFreq policy
 939  *      @policy: policy to be set.
 940  *
 941  *      Sets a new CPU frequency and voltage scaling policy.
 942  */
 943 int cpufreq_set_policy(struct cpufreq_policy *policy)
 944 {
 945         int ret = 0;
 946         struct cpufreq_policy *data;
 947
 948         if (!policy)
 949                 return -EINVAL;
 950
 951         data = cpufreq_cpu_get(policy->cpu);
 952         if (!data)
 953                 return -EINVAL;
 954
 955         /* lock this CPU */
 956         down(&data->lock);
 957
 958         ret = __cpufreq_set_policy(data, policy);
 959         data->user_policy.min = data->min;
 960         data->user_policy.max = data->max;
 961         data->user_policy.policy = data->policy;
 962         data->user_policy.governor = data->governor;
 963
 964         up(&data->lock);
 965         cpufreq_cpu_put(data);
 966
 967         return ret;
 968 }
 969 EXPORT_SYMBOL(cpufreq_set_policy);
 970
 971
 972 /**
 973  *      cpufreq_update_policy - re-evaluate an existing cpufreq policy
 974  *      @cpu: CPU which shall be re-evaluated
 975  *
 976  *      Usefull for policy notifiers which have different necessities
 977  *      at different times.
 978  */
 979 int cpufreq_update_policy(unsigned int cpu)
 980 {
 981         struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
 982         struct cpufreq_policy policy;
 983         int ret = 0;
 984
 985         if (!data)
 986                 return -ENODEV;
 987
 988         down(&data->lock);
 989
 990         memcpy(&policy,
 991                data,
 992                sizeof(struct cpufreq_policy));
 993         policy.min = data->user_policy.min;
 994         policy.max = data->user_policy.max;
 995         policy.policy = data->user_policy.policy;
 996         policy.governor = data->user_policy.governor;
 997
 998         ret = __cpufreq_set_policy(data, &policy);
 999
1000         up(&data->lock);
1001
1002         cpufreq_cpu_put(data);
1003         return ret;
1004 }
1005 EXPORT_SYMBOL(cpufreq_update_policy);
1006
1007
1008 /*********************************************************************
1009  *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
1010  *********************************************************************/
1011
1012 /**
1013  * adjust_jiffies - adjust the system "loops_per_jiffy"
1014  *
1015  * This function alters the system "loops_per_jiffy" for the clock
1016  * speed change. Note that loops_per_jiffy cannot be updated on SMP
1017  * systems as each CPU might be scaled differently. So, use the arch
1018  * per-CPU loops_per_jiffy value wherever possible.
1019  */
1020 #ifndef CONFIG_SMP
1021 static unsigned long l_p_j_ref;
1022 static unsigned int  l_p_j_ref_freq;
1023
1024 static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
1025 {
1026         if (ci->flags & CPUFREQ_CONST_LOOPS)
1027                 return;
1028
1029         if (!l_p_j_ref_freq) {
1030                 l_p_j_ref = loops_per_jiffy;
1031                 l_p_j_ref_freq = ci->old;
1032         }
1033         if ((val == CPUFREQ_PRECHANGE  && ci->old < ci->new) ||
1034             (val == CPUFREQ_POSTCHANGE && ci->old > ci->new) ||
1035             (val == CPUFREQ_RESUMECHANGE))
1036                 loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq, ci->new);
1037 }
1038 #else
1039 static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci) { return; }
1040 #endif
1041
1042
1043 /**
1044  * cpufreq_notify_transition - call notifier chain and adjust_jiffies on frequency transition
1045  *
1046  * This function calls the transition notifiers and the "adjust_jiffies" function. It is called
1047  * twice on all CPU frequency changes that have external effects.
1048  */
1049 void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
1050 {
1051         BUG_ON(irqs_disabled());
1052
1053         freqs->flags = cpufreq_driver->flags;
1054
1055         down_read(&cpufreq_notifier_rwsem);
1056         switch (state) {
1057         case CPUFREQ_PRECHANGE:
1058                 /* detect if the driver reported a value as "old frequency" which
1059                  * is not equal to what the cpufreq core thinks is "old frequency".
1060                  */
1061                 if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
1062                         if ((likely(cpufreq_cpu_data[freqs->cpu]->cur)) &&
1063                             (unlikely(freqs->old != cpufreq_cpu_data[freqs->cpu]->cur)))
1064                         {
1065                                 if (cpufreq_driver->flags & CPUFREQ_PANIC_OUTOFSYNC)
1066                                         panic("CPU Frequency is out of sync.");
1067
1068                                 printk(KERN_WARNING "Warning: CPU frequency out of sync: "
1069                                        "cpufreq and timing core thinks of %u, is %u kHz.\n",
1070                                        cpufreq_cpu_data[freqs->cpu]->cur, freqs->old);
1071                                 freqs->old = cpufreq_cpu_data[freqs->cpu]->cur;
1072                         }
1073                 }
1074                 notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_PRECHANGE, freqs);
1075                 adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
1076                 break;
1077         case CPUFREQ_POSTCHANGE:
1078                 adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
1079                 notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_POSTCHANGE, freqs);
1080                 cpufreq_cpu_data[freqs->cpu]->cur = freqs->new;
1081                 break;
1082         }
1083         up_read(&cpufreq_notifier_rwsem);
1084 }
1085 EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
1086
1087
1088
1089 /*********************************************************************
1090  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
1091  *********************************************************************/
1092
1093 /**
1094  * cpufreq_register_driver - register a CPU Frequency driver
1095  * @driver_data: A struct cpufreq_driver containing the values#
1096  * submitted by the CPU Frequency driver.
1097  *
1098  *   Registers a CPU Frequency driver to this core code. This code
1099  * returns zero on success, -EBUSY when another driver got here first
1100  * (and isn't unregistered in the meantime).
1101  *
1102  */
1103 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
1104 {
1105         unsigned long flags;
1106         int ret;
1107
1108         if (!driver_data || !driver_data->verify || !driver_data->init ||
1109             ((!driver_data->setpolicy) && (!driver_data->target)))
1110                 return -EINVAL;
1111
1112         if (driver_data->setpolicy)
1113                 driver_data->flags |= CPUFREQ_CONST_LOOPS;
1114
1115         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1116         if (cpufreq_driver) {
1117                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1118                 return -EBUSY;
1119         }
1120         cpufreq_driver = driver_data;
1121         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1122
1123         ret = sysdev_driver_register(&cpu_sysdev_class,&cpufreq_sysdev_driver);
1124
1125         if ((!ret) && !(cpufreq_driver->flags & CPUFREQ_STICKY)) {
1126                 int i;
1127                 ret = -ENODEV;
1128
1129                 /* check for at least one working CPU */
1130                 for (i=0; i<NR_CPUS; i++)
1131                         if (cpufreq_cpu_data[i])
1132                                 ret = 0;
1133
1134                 /* if all ->init() calls failed, unregister */
1135                 if (ret) {
1136                         sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
1137
1138                         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1139                         cpufreq_driver = NULL;
1140                         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1141                 }
1142         }
1143
1144         return (ret);
1145 }
1146 EXPORT_SYMBOL_GPL(cpufreq_register_driver);
1147
1148
1149 /**
1150  * cpufreq_unregister_driver - unregister the current CPUFreq driver
1151  *
1152  *    Unregister the current CPUFreq driver. Only call this if you have
1153  * the right to do so, i.e. if you have succeeded in initialising before!
1154  * Returns zero if successful, and -EINVAL if the cpufreq_driver is
1155  * currently not initialised.
1156  */
1157 int cpufreq_unregister_driver(struct cpufreq_driver *driver)
1158 {
1159         unsigned long flags;
1160
1161         if (!cpufreq_driver || (driver != cpufreq_driver))
1162                 return -EINVAL;
1163
1164         sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
1165
1166         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1167         cpufreq_driver = NULL;
1168         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1169
1170         return 0;
1171 }
1172 EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);