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 snprintf(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 snprintf(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 += snprintf(&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                 return -ENOMEM;
 365         memset(policy, 0, sizeof(struct cpufreq_policy));
 366
 367         policy->cpu = cpu;
 368         init_MUTEX_LOCKED(&policy->lock);
 369         init_completion(&policy->kobj_unregister);
 370
 371         /* call driver. From then on the cpufreq must be able
 372          * to accept all calls to ->verify and ->setpolicy for this CPU
 373          */
 374         ret = cpufreq_driver->init(policy);
 375         if (ret)
 376                 goto err_out;
 377
 378         memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
 379
 380         /* prepare interface data */
 381         policy->kobj.parent = &sys_dev->kobj;
 382         policy->kobj.ktype = &ktype_cpufreq;
 383         strlcpy(policy->kobj.name, "cpufreq", KOBJ_NAME_LEN);
 384
 385         ret = kobject_register(&policy->kobj);
 386         if (ret)
 387                 goto err_out;
 388
 389         /* set up files for this cpu device */
 390         drv_attr = cpufreq_driver->attr;
 391         while ((drv_attr) && (*drv_attr)) {
 392                 sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
 393                 drv_attr++;
 394         }
 395
 396         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 397         cpufreq_cpu_data[cpu] = policy;
 398         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 399         policy->governor = NULL; /* to assure that the starting sequence is
 400                                   * run in cpufreq_set_policy */
 401         up(&policy->lock);
 402
 403         /* set default policy */
 404
 405         ret = cpufreq_set_policy(&new_policy);
 406         if (ret)
 407                 goto err_out_unregister;
 408
 409         module_put(cpufreq_driver->owner);
 410         return 0;
 411
 412
 413  err_out_unregister:
 414         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 415         cpufreq_cpu_data[cpu] = NULL;
 416         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 417
 418         kobject_unregister(&policy->kobj);
 419         wait_for_completion(&policy->kobj_unregister);
 420
 421  err_out:
 422         kfree(policy);
 423         module_put(cpufreq_driver->owner);
 424         return ret;
 425 }
 426
 427
 428 /**
 429  * cpufreq_remove_dev - remove a CPU device
 430  *
 431  * Removes the cpufreq interface for a CPU device.
 432  */
 433 static int cpufreq_remove_dev (struct sys_device * sys_dev)
 434 {
 435         unsigned int cpu = sys_dev->id;
 436         unsigned long flags;
 437         struct cpufreq_policy *data;
 438
 439         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 440         data = cpufreq_cpu_data[cpu];
 441
 442         if (!data) {
 443                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 444                 return -EINVAL;
 445         }
 446         cpufreq_cpu_data[cpu] = NULL;
 447         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 448
 449         if (!kobject_get(&data->kobj))
 450                 return -EFAULT;
 451
 452         if (cpufreq_driver->target)
 453                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
 454
 455         kobject_unregister(&data->kobj);
 456
 457         kobject_put(&data->kobj);
 458
 459         /* we need to make sure that the underlying kobj is actually
 460          * not referenced anymore by anybody before we proceed with
 461          * unloading.
 462          */
 463         wait_for_completion(&data->kobj_unregister);
 464
 465         if (cpufreq_driver->exit)
 466                 cpufreq_driver->exit(data);
 467
 468         kfree(data);
 469
 470         return 0;
 471 }
 472
 473 /**
 474  *      cpufreq_resume - restore the CPU clock frequency after resume
 475  *
 476  *      Restore the CPU clock frequency so that our idea of the current
 477  *      frequency reflects the actual hardware.
 478  */
 479 static int cpufreq_resume(struct sys_device * sysdev)
 480 {
 481         int cpu = sysdev->id;
 482         unsigned int ret = 0;
 483         struct cpufreq_policy *cpu_policy;
 484
 485         if (!cpu_online(cpu))
 486                 return 0;
 487
 488         /* we may be lax here as interrupts are off. Nonetheless
 489          * we need to grab the correct cpu policy, as to check
 490          * whether we really run on this CPU.
 491          */
 492
 493         cpu_policy = cpufreq_cpu_get(cpu);
 494         if (!cpu_policy)
 495                 return -EINVAL;
 496
 497         if (cpufreq_driver->resume)
 498                 ret = cpufreq_driver->resume(cpu_policy);
 499         if (ret) {
 500                 printk(KERN_ERR "cpufreq: resume failed in ->resume step on CPU %u\n", cpu_policy->cpu);
 501                 goto out;
 502         }
 503
 504         if (cpufreq_driver->setpolicy)
 505                 ret = cpufreq_driver->setpolicy(cpu_policy);
 506         else
 507         /* CPUFREQ_RELATION_H or CPUFREQ_RELATION_L have the same effect here, as cpu_policy->cur is known
 508          * to be a valid and exact target frequency
 509          */
 510                 ret = cpufreq_driver->target(cpu_policy, cpu_policy->cur, CPUFREQ_RELATION_H);
 511
 512         if (ret) {
 513                 printk(KERN_ERR "cpufreq: resume failed in ->setpolicy/target step on CPU %u\n", cpu_policy->cpu);
 514                 goto out;
 515         }
 516
 517  out:
 518         cpufreq_cpu_put(cpu_policy);
 519
 520         return ret;
 521 }
 522
 523 static struct sysdev_driver cpufreq_sysdev_driver = {
 524         .add            = cpufreq_add_dev,
 525         .remove         = cpufreq_remove_dev,
 526         .resume         = cpufreq_resume,
 527 };
 528
 529
 530 /*********************************************************************
 531  *                     NOTIFIER LISTS INTERFACE                      *
 532  *********************************************************************/
 533
 534 /**
 535  *      cpufreq_register_notifier - register a driver with cpufreq
 536  *      @nb: notifier function to register
 537  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
 538  *
 539  *      Add a driver to one of two lists: either a list of drivers that
 540  *      are notified about clock rate changes (once before and once after
 541  *      the transition), or a list of drivers that are notified about
 542  *      changes in cpufreq policy.
 543  *
 544  *      This function may sleep, and has the same return conditions as
 545  *      notifier_chain_register.
 546  */
 547 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
 548 {
 549         int ret;
 550
 551         down_write(&cpufreq_notifier_rwsem);
 552         switch (list) {
 553         case CPUFREQ_TRANSITION_NOTIFIER:
 554                 ret = notifier_chain_register(&cpufreq_transition_notifier_list, nb);
 555                 break;
 556         case CPUFREQ_POLICY_NOTIFIER:
 557                 ret = notifier_chain_register(&cpufreq_policy_notifier_list, nb);
 558                 break;
 559         default:
 560                 ret = -EINVAL;
 561         }
 562         up_write(&cpufreq_notifier_rwsem);
 563
 564         return ret;
 565 }
 566 EXPORT_SYMBOL(cpufreq_register_notifier);
 567
 568
 569 /**
 570  *      cpufreq_unregister_notifier - unregister a driver with cpufreq
 571  *      @nb: notifier block to be unregistered
 572  *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
 573  *
 574  *      Remove a driver from the CPU frequency notifier list.
 575  *
 576  *      This function may sleep, and has the same return conditions as
 577  *      notifier_chain_unregister.
 578  */
 579 int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
 580 {
 581         int ret;
 582
 583         down_write(&cpufreq_notifier_rwsem);
 584         switch (list) {
 585         case CPUFREQ_TRANSITION_NOTIFIER:
 586                 ret = notifier_chain_unregister(&cpufreq_transition_notifier_list, nb);
 587                 break;
 588         case CPUFREQ_POLICY_NOTIFIER:
 589                 ret = notifier_chain_unregister(&cpufreq_policy_notifier_list, nb);
 590                 break;
 591         default:
 592                 ret = -EINVAL;
 593         }
 594         up_write(&cpufreq_notifier_rwsem);
 595
 596         return ret;
 597 }
 598 EXPORT_SYMBOL(cpufreq_unregister_notifier);
 599
 600
 601 /*********************************************************************
 602  *                              GOVERNORS                            *
 603  *********************************************************************/
 604
 605
 606 int __cpufreq_driver_target(struct cpufreq_policy *policy,
 607                             unsigned int target_freq,
 608                             unsigned int relation)
 609 {
 610         return cpufreq_driver->target(policy, target_freq, relation);
 611 }
 612 EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
 613
 614
 615 int cpufreq_driver_target(struct cpufreq_policy *policy,
 616                           unsigned int target_freq,
 617                           unsigned int relation)
 618 {
 619         unsigned int ret;
 620
 621         policy = cpufreq_cpu_get(policy->cpu);
 622         if (!policy)
 623                 return -EINVAL;
 624
 625         down(&policy->lock);
 626
 627         ret = __cpufreq_driver_target(policy, target_freq, relation);
 628
 629         up(&policy->lock);
 630
 631         cpufreq_cpu_put(policy);
 632
 633         return ret;
 634 }
 635 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
 636
 637
 638 static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event)
 639 {
 640         int ret = -EINVAL;
 641
 642         if (!try_module_get(policy->governor->owner))
 643                 return -EINVAL;
 644
 645         ret = policy->governor->governor(policy, event);
 646
 647         /* we keep one module reference alive for each CPU governed by this CPU */
 648         if ((event != CPUFREQ_GOV_START) || ret)
 649                 module_put(policy->governor->owner);
 650         if ((event == CPUFREQ_GOV_STOP) && !ret)
 651                 module_put(policy->governor->owner);
 652
 653         return ret;
 654 }
 655
 656
 657 int cpufreq_governor(unsigned int cpu, unsigned int event)
 658 {
 659         int ret = 0;
 660         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
 661
 662         if (!policy)
 663                 return -EINVAL;
 664
 665         down(&policy->lock);
 666         ret = __cpufreq_governor(policy, event);
 667         up(&policy->lock);
 668
 669         cpufreq_cpu_put(policy);
 670
 671         return ret;
 672 }
 673 EXPORT_SYMBOL_GPL(cpufreq_governor);
 674
 675
 676 int cpufreq_register_governor(struct cpufreq_governor *governor)
 677 {
 678         struct cpufreq_governor *t;
 679
 680         if (!governor)
 681                 return -EINVAL;
 682
 683         down(&cpufreq_governor_sem);
 684
 685         list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
 686                 if (!strnicmp(governor->name,t->name,CPUFREQ_NAME_LEN)) {
 687                         up(&cpufreq_governor_sem);
 688                         return -EBUSY;
 689                 }
 690         }
 691         list_add(&governor->governor_list, &cpufreq_governor_list);
 692
 693         up(&cpufreq_governor_sem);
 694
 695         return 0;
 696 }
 697 EXPORT_SYMBOL_GPL(cpufreq_register_governor);
 698
 699
 700 void cpufreq_unregister_governor(struct cpufreq_governor *governor)
 701 {
 702         if (!governor)
 703                 return;
 704
 705         down(&cpufreq_governor_sem);
 706         list_del(&governor->governor_list);
 707         up(&cpufreq_governor_sem);
 708         return;
 709 }
 710 EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
 711
 712
 713
 714 /*********************************************************************
 715  *                          POLICY INTERFACE                         *
 716  *********************************************************************/
 717
 718 /**
 719  * cpufreq_get_policy - get the current cpufreq_policy
 720  * @policy: struct cpufreq_policy into which the current cpufreq_policy is written
 721  *
 722  * Reads the current cpufreq policy.
 723  */
 724 int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
 725 {
 726         struct cpufreq_policy *cpu_policy;
 727         if (!policy)
 728                 return -EINVAL;
 729
 730         cpu_policy = cpufreq_cpu_get(cpu);
 731         if (!cpu_policy)
 732                 return -EINVAL;
 733
 734         down(&cpu_policy->lock);
 735         memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
 736         up(&cpu_policy->lock);
 737
 738         cpufreq_cpu_put(cpu_policy);
 739
 740         return 0;
 741 }
 742 EXPORT_SYMBOL(cpufreq_get_policy);
 743
 744
 745 static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_policy *policy)
 746 {
 747         int ret = 0;
 748
 749         memcpy(&policy->cpuinfo,
 750                &data->cpuinfo,
 751                sizeof(struct cpufreq_cpuinfo));
 752
 753         /* verify the cpu speed can be set within this limit */
 754         ret = cpufreq_driver->verify(policy);
 755         if (ret)
 756                 goto error_out;
 757
 758         down_read(&cpufreq_notifier_rwsem);
 759
 760         /* adjust if necessary - all reasons */
 761         notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_ADJUST,
 762                             policy);
 763
 764         /* adjust if necessary - hardware incompatibility*/
 765         notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_INCOMPATIBLE,
 766                             policy);
 767
 768         /* verify the cpu speed can be set within this limit,
 769            which might be different to the first one */
 770         ret = cpufreq_driver->verify(policy);
 771         if (ret) {
 772                 up_read(&cpufreq_notifier_rwsem);
 773                 goto error_out;
 774         }
 775
 776         /* notification of the new policy */
 777         notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY,
 778                             policy);
 779
 780         up_read(&cpufreq_notifier_rwsem);
 781
 782         data->min    = policy->min;
 783         data->max    = policy->max;
 784
 785         if (cpufreq_driver->setpolicy) {
 786                 data->policy = policy->policy;
 787                 ret = cpufreq_driver->setpolicy(policy);
 788         } else {
 789                 if (policy->governor != data->governor) {
 790                         /* save old, working values */
 791                         struct cpufreq_governor *old_gov = data->governor;
 792
 793                         /* end old governor */
 794                         if (data->governor)
 795                                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
 796
 797                         /* start new governor */
 798                         data->governor = policy->governor;
 799                         if (__cpufreq_governor(data, CPUFREQ_GOV_START)) {
 800                                 /* new governor failed, so re-start old one */
 801                                 if (old_gov) {
 802                                         data->governor = old_gov;
 803                                         __cpufreq_governor(data, CPUFREQ_GOV_START);
 804                                 }
 805                                 ret = -EINVAL;
 806                                 goto error_out;
 807                         }
 808                         /* might be a policy change, too, so fall through */
 809                 }
 810                 __cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
 811         }
 812
 813  error_out:
 814         return ret;
 815 }
 816
 817 /**
 818  *      cpufreq_set_policy - set a new CPUFreq policy
 819  *      @policy: policy to be set.
 820  *
 821  *      Sets a new CPU frequency and voltage scaling policy.
 822  */
 823 int cpufreq_set_policy(struct cpufreq_policy *policy)
 824 {
 825         int ret = 0;
 826         struct cpufreq_policy *data;
 827
 828         if (!policy)
 829                 return -EINVAL;
 830
 831         data = cpufreq_cpu_get(policy->cpu);
 832         if (!data)
 833                 return -EINVAL;
 834
 835         /* lock this CPU */
 836         down(&data->lock);
 837
 838         ret = __cpufreq_set_policy(data, policy);
 839         data->user_policy.min = data->min;
 840         data->user_policy.max = data->max;
 841         data->user_policy.policy = data->policy;
 842         data->user_policy.governor = data->governor;
 843
 844         up(&data->lock);
 845         cpufreq_cpu_put(data);
 846
 847         return ret;
 848 }
 849 EXPORT_SYMBOL(cpufreq_set_policy);
 850
 851
 852 /**
 853  *      cpufreq_update_policy - re-evaluate an existing cpufreq policy
 854  *      @cpu: CPU which shall be re-evaluated
 855  *
 856  *      Usefull for policy notifiers which have different necessities
 857  *      at different times.
 858  */
 859 int cpufreq_update_policy(unsigned int cpu)
 860 {
 861         struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
 862         struct cpufreq_policy policy;
 863         int ret = 0;
 864
 865         if (!data)
 866                 return -ENODEV;
 867
 868         down(&data->lock);
 869
 870         memcpy(&policy,
 871                data,
 872                sizeof(struct cpufreq_policy));
 873         policy.min = data->user_policy.min;
 874         policy.max = data->user_policy.max;
 875         policy.policy = data->user_policy.policy;
 876         policy.governor = data->user_policy.governor;
 877
 878         ret = __cpufreq_set_policy(data, &policy);
 879
 880         up(&data->lock);
 881
 882         cpufreq_cpu_put(data);
 883         return ret;
 884 }
 885 EXPORT_SYMBOL(cpufreq_update_policy);
 886
 887
 888 /*********************************************************************
 889  *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
 890  *********************************************************************/
 891
 892 /**
 893  * adjust_jiffies - adjust the system "loops_per_jiffy"
 894  *
 895  * This function alters the system "loops_per_jiffy" for the clock
 896  * speed change. Note that loops_per_jiffy cannot be updated on SMP
 897  * systems as each CPU might be scaled differently. So, use the arch
 898  * per-CPU loops_per_jiffy value wherever possible.
 899  */
 900 #ifndef CONFIG_SMP
 901 static unsigned long l_p_j_ref;
 902 static unsigned int  l_p_j_ref_freq;
 903
 904 static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 905 {
 906         if (!l_p_j_ref_freq) {
 907                 l_p_j_ref = loops_per_jiffy;
 908                 l_p_j_ref_freq = ci->old;
 909         }
 910         if ((val == CPUFREQ_PRECHANGE  && ci->old < ci->new) ||
 911             (val == CPUFREQ_POSTCHANGE && ci->old > ci->new))
 912                 loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq, ci->new);
 913 }
 914 #else
 915 #define adjust_jiffies(x...) do {} while (0)
 916 #endif
 917
 918
 919 /**
 920  * cpufreq_notify_transition - call notifier chain and adjust_jiffies on frequency transition
 921  *
 922  * This function calls the transition notifiers and the "adjust_jiffies" function. It is called
 923  * twice on all CPU frequency changes that have external effects.
 924  */
 925 void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
 926 {
 927         if (irqs_disabled())
 928                 return;   /* Only valid if we're in the resume process where
 929                            * everyone knows what CPU frequency we are at */
 930
 931         down_read(&cpufreq_notifier_rwsem);
 932         switch (state) {
 933         case CPUFREQ_PRECHANGE:
 934                 notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_PRECHANGE, freqs);
 935                 adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
 936                 break;
 937         case CPUFREQ_POSTCHANGE:
 938                 adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
 939                 notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_POSTCHANGE, freqs);
 940                 cpufreq_cpu_data[freqs->cpu]->cur = freqs->new;
 941                 break;
 942         }
 943         up_read(&cpufreq_notifier_rwsem);
 944 }
 945 EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
 946
 947
 948
 949 /*********************************************************************
 950  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
 951  *********************************************************************/
 952
 953 /**
 954  * cpufreq_register_driver - register a CPU Frequency driver
 955  * @driver_data: A struct cpufreq_driver containing the values#
 956  * submitted by the CPU Frequency driver.
 957  *
 958  *   Registers a CPU Frequency driver to this core code. This code
 959  * returns zero on success, -EBUSY when another driver got here first
 960  * (and isn't unregistered in the meantime).
 961  *
 962  */
 963 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 964 {
 965         unsigned long flags;
 966
 967         if (!driver_data || !driver_data->verify || !driver_data->init ||
 968             ((!driver_data->setpolicy) && (!driver_data->target)))
 969                 return -EINVAL;
 970
 971         spin_lock_irqsave(&cpufreq_driver_lock, flags);
 972         if (cpufreq_driver) {
 973                 spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 974                 return -EBUSY;
 975         }
 976         cpufreq_driver = driver_data;
 977         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 978
 979         return sysdev_driver_register(&cpu_sysdev_class,&cpufreq_sysdev_driver);
 980 }
 981 EXPORT_SYMBOL_GPL(cpufreq_register_driver);
 982
 983
 984 /**
 985  * cpufreq_unregister_driver - unregister the current CPUFreq driver
 986  *
 987  *    Unregister the current CPUFreq driver. Only call this if you have
 988  * the right to do so, i.e. if you have succeeded in initialising before!
 989  * Returns zero if successful, and -EINVAL if the cpufreq_driver is
 990  * currently not initialised.
 991  */
 992 int cpufreq_unregister_driver(struct cpufreq_driver *driver)
 993 {
 994         unsigned long flags;
 995
 996         if (!cpufreq_driver || (driver != cpufreq_driver))
 997                 return -EINVAL;
 998
 999         sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
1000
1001         spin_lock_irqsave(&cpufreq_driver_lock, flags);
1002         cpufreq_driver = NULL;
1003         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
1004
1005         return 0;
1006 }
1007 EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);