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