drivers/cpufreq/cpufreq_ondemand.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_ondemand.c
   3  *
   4  *  Copyright (C)  2001 Russell King
   5  *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   6  *                      Jun Nakajima <jun.nakajima@intel.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/cpu.h>
  16 #include <linux/percpu-defs.h>
  17 #include <linux/slab.h>
  18 #include <linux/tick.h>
  19 #include "cpufreq_governor.h"
  20
  21 /* On-demand governor macros */
  22 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  23 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  24 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
  25 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  26 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  27 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
  28 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  29
  30 static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
  31
  32 static struct od_ops od_ops;
  33
  34 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
  35 static struct cpufreq_governor cpufreq_gov_ondemand;
  36 #endif
  37
  38 static unsigned int default_powersave_bias;
  39
  40 static void ondemand_powersave_bias_init_cpu(int cpu)
  41 {
  42         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
  43
  44         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
  45         dbs_info->freq_lo = 0;
  46 }
  47
  48 /*
  49  * Not all CPUs want IO time to be accounted as busy; this depends on how
  50  * efficient idling at a higher frequency/voltage is.
  51  * Pavel Machek says this is not so for various generations of AMD and old
  52  * Intel systems.
  53  * Mike Chan (android.com) claims this is also not true for ARM.
  54  * Because of this, whitelist specific known (series) of CPUs by default, and
  55  * leave all others up to the user.
  56  */
  57 static int should_io_be_busy(void)
  58 {
  59 #if defined(CONFIG_X86)
  60         /*
  61          * For Intel, Core 2 (model 15) and later have an efficient idle.
  62          */
  63         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  64                         boot_cpu_data.x86 == 6 &&
  65                         boot_cpu_data.x86_model >= 15)
  66                 return 1;
  67 #endif
  68         return 0;
  69 }
  70
  71 /*
  72  * Find right freq to be set now with powersave_bias on.
  73  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
  74  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
  75  */
  76 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
  77                 unsigned int freq_next, unsigned int relation)
  78 {
  79         unsigned int freq_req, freq_reduc, freq_avg;
  80         unsigned int freq_hi, freq_lo;
  81         unsigned int index = 0;
  82         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
  83         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
  84                                                    policy->cpu);
  85         struct dbs_data *dbs_data = policy->governor_data;
  86         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  87
  88         if (!dbs_info->freq_table) {
  89                 dbs_info->freq_lo = 0;
  90                 dbs_info->freq_lo_jiffies = 0;
  91                 return freq_next;
  92         }
  93
  94         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
  95                         relation, &index);
  96         freq_req = dbs_info->freq_table[index].frequency;
  97         freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
  98         freq_avg = freq_req - freq_reduc;
  99
 100         /* Find freq bounds for freq_avg in freq_table */
 101         index = 0;
 102         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 103                         CPUFREQ_RELATION_H, &index);
 104         freq_lo = dbs_info->freq_table[index].frequency;
 105         index = 0;
 106         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 107                         CPUFREQ_RELATION_L, &index);
 108         freq_hi = dbs_info->freq_table[index].frequency;
 109
 110         /* Find out how long we have to be in hi and lo freqs */
 111         if (freq_hi == freq_lo) {
 112                 dbs_info->freq_lo = 0;
 113                 dbs_info->freq_lo_jiffies = 0;
 114                 return freq_lo;
 115         }
 116         jiffies_total = usecs_to_jiffies(od_tuners->sampling_rate);
 117         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 118         jiffies_hi += ((freq_hi - freq_lo) / 2);
 119         jiffies_hi /= (freq_hi - freq_lo);
 120         jiffies_lo = jiffies_total - jiffies_hi;
 121         dbs_info->freq_lo = freq_lo;
 122         dbs_info->freq_lo_jiffies = jiffies_lo;
 123         dbs_info->freq_hi_jiffies = jiffies_hi;
 124         return freq_hi;
 125 }
 126
 127 static void ondemand_powersave_bias_init(void)
 128 {
 129         int i;
 130         for_each_online_cpu(i) {
 131                 ondemand_powersave_bias_init_cpu(i);
 132         }
 133 }
 134
 135 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
 136 {
 137         struct dbs_data *dbs_data = policy->governor_data;
 138         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 139
 140         if (od_tuners->powersave_bias)
 141                 freq = od_ops.powersave_bias_target(policy, freq,
 142                                 CPUFREQ_RELATION_H);
 143         else if (policy->cur == policy->max)
 144                 return;
 145
 146         __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
 147                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 148 }
 149
 150 /*
 151  * Every sampling_rate, we check, if current idle time is less than 20%
 152  * (default), then we try to increase frequency. Else, we adjust the frequency
 153  * proportional to load.
 154  */
 155 static void od_check_cpu(int cpu, unsigned int load)
 156 {
 157         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 158         struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
 159         struct dbs_data *dbs_data = policy->governor_data;
 160         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 161
 162         dbs_info->freq_lo = 0;
 163
 164         /* Check for frequency increase */
 165         if (load > od_tuners->up_threshold) {
 166                 /* If switching to max speed, apply sampling_down_factor */
 167                 if (policy->cur < policy->max)
 168                         dbs_info->rate_mult =
 169                                 od_tuners->sampling_down_factor;
 170                 dbs_freq_increase(policy, policy->max);
 171                 return;
 172         } else {
 173                 /* Calculate the next frequency proportional to load */
 174                 unsigned int freq_next;
 175                 freq_next = load * policy->cpuinfo.max_freq / 100;
 176
 177                 /* No longer fully busy, reset rate_mult */
 178                 dbs_info->rate_mult = 1;
 179
 180                 if (!od_tuners->powersave_bias) {
 181                         __cpufreq_driver_target(policy, freq_next,
 182                                         CPUFREQ_RELATION_L);
 183                         return;
 184                 }
 185
 186                 freq_next = od_ops.powersave_bias_target(policy, freq_next,
 187                                         CPUFREQ_RELATION_L);
 188                 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
 189         }
 190 }
 191
 192 static void od_dbs_timer(struct work_struct *work)
 193 {
 194         struct od_cpu_dbs_info_s *dbs_info =
 195                 container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
 196         unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 197         struct od_cpu_dbs_info_s *core_dbs_info = &per_cpu(od_cpu_dbs_info,
 198                         cpu);
 199         struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data;
 200         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 201         int delay = 0, sample_type = core_dbs_info->sample_type;
 202         bool modify_all = true;
 203
 204         mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 205         if (!need_load_eval(&core_dbs_info->cdbs, od_tuners->sampling_rate)) {
 206                 modify_all = false;
 207                 goto max_delay;
 208         }
 209
 210         /* Common NORMAL_SAMPLE setup */
 211         core_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 212         if (sample_type == OD_SUB_SAMPLE) {
 213                 delay = core_dbs_info->freq_lo_jiffies;
 214                 __cpufreq_driver_target(core_dbs_info->cdbs.cur_policy,
 215                                 core_dbs_info->freq_lo, CPUFREQ_RELATION_H);
 216         } else {
 217                 dbs_check_cpu(dbs_data, cpu);
 218                 if (core_dbs_info->freq_lo) {
 219                         /* Setup timer for SUB_SAMPLE */
 220                         core_dbs_info->sample_type = OD_SUB_SAMPLE;
 221                         delay = core_dbs_info->freq_hi_jiffies;
 222                 }
 223         }
 224
 225 max_delay:
 226         if (!delay)
 227                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 228                                 * core_dbs_info->rate_mult);
 229
 230         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all);
 231         mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 232 }
 233
 234 /************************** sysfs interface ************************/
 235 static struct common_dbs_data od_dbs_cdata;
 236
 237 /**
 238  * update_sampling_rate - update sampling rate effective immediately if needed.
 239  * @new_rate: new sampling rate
 240  *
 241  * If new rate is smaller than the old, simply updating
 242  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 243  * original sampling_rate was 1 second and the requested new sampling rate is 10
 244  * ms because the user needs immediate reaction from ondemand governor, but not
 245  * sure if higher frequency will be required or not, then, the governor may
 246  * change the sampling rate too late; up to 1 second later. Thus, if we are
 247  * reducing the sampling rate, we need to make the new value effective
 248  * immediately.
 249  */
 250 static void update_sampling_rate(struct dbs_data *dbs_data,
 251                 unsigned int new_rate)
 252 {
 253         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 254         int cpu;
 255
 256         od_tuners->sampling_rate = new_rate = max(new_rate,
 257                         dbs_data->min_sampling_rate);
 258
 259         for_each_online_cpu(cpu) {
 260                 struct cpufreq_policy *policy;
 261                 struct od_cpu_dbs_info_s *dbs_info;
 262                 unsigned long next_sampling, appointed_at;
 263
 264                 policy = cpufreq_cpu_get(cpu);
 265                 if (!policy)
 266                         continue;
 267                 if (policy->governor != &cpufreq_gov_ondemand) {
 268                         cpufreq_cpu_put(policy);
 269                         continue;
 270                 }
 271                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 272                 cpufreq_cpu_put(policy);
 273
 274                 mutex_lock(&dbs_info->cdbs.timer_mutex);
 275
 276                 if (!delayed_work_pending(&dbs_info->cdbs.work)) {
 277                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 278                         continue;
 279                 }
 280
 281                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 282                 appointed_at = dbs_info->cdbs.work.timer.expires;
 283
 284                 if (time_before(next_sampling, appointed_at)) {
 285
 286                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 287                         cancel_delayed_work_sync(&dbs_info->cdbs.work);
 288                         mutex_lock(&dbs_info->cdbs.timer_mutex);
 289
 290                         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy,
 291                                         usecs_to_jiffies(new_rate), true);
 292
 293                 }
 294                 mutex_unlock(&dbs_info->cdbs.timer_mutex);
 295         }
 296 }
 297
 298 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 299                 size_t count)
 300 {
 301         unsigned int input;
 302         int ret;
 303         ret = sscanf(buf, "%u", &input);
 304         if (ret != 1)
 305                 return -EINVAL;
 306
 307         update_sampling_rate(dbs_data, input);
 308         return count;
 309 }
 310
 311 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
 312                 size_t count)
 313 {
 314         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 315         unsigned int input;
 316         int ret;
 317         unsigned int j;
 318
 319         ret = sscanf(buf, "%u", &input);
 320         if (ret != 1)
 321                 return -EINVAL;
 322         od_tuners->io_is_busy = !!input;
 323
 324         /* we need to re-evaluate prev_cpu_idle */
 325         for_each_online_cpu(j) {
 326                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 327                                                                         j);
 328                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 329                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 330         }
 331         return count;
 332 }
 333
 334 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 335                 size_t count)
 336 {
 337         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 338         unsigned int input;
 339         int ret;
 340         ret = sscanf(buf, "%u", &input);
 341
 342         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 343                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 344                 return -EINVAL;
 345         }
 346
 347         od_tuners->up_threshold = input;
 348         return count;
 349 }
 350
 351 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 352                 const char *buf, size_t count)
 353 {
 354         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 355         unsigned int input, j;
 356         int ret;
 357         ret = sscanf(buf, "%u", &input);
 358
 359         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 360                 return -EINVAL;
 361         od_tuners->sampling_down_factor = input;
 362
 363         /* Reset down sampling multiplier in case it was active */
 364         for_each_online_cpu(j) {
 365                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 366                                 j);
 367                 dbs_info->rate_mult = 1;
 368         }
 369         return count;
 370 }
 371
 372 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 373                 const char *buf, size_t count)
 374 {
 375         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 376         unsigned int input;
 377         int ret;
 378
 379         unsigned int j;
 380
 381         ret = sscanf(buf, "%u", &input);
 382         if (ret != 1)
 383                 return -EINVAL;
 384
 385         if (input > 1)
 386                 input = 1;
 387
 388         if (input == od_tuners->ignore_nice_load) { /* nothing to do */
 389                 return count;
 390         }
 391         od_tuners->ignore_nice_load = input;
 392
 393         /* we need to re-evaluate prev_cpu_idle */
 394         for_each_online_cpu(j) {
 395                 struct od_cpu_dbs_info_s *dbs_info;
 396                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 397                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 398                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 399                 if (od_tuners->ignore_nice_load)
 400                         dbs_info->cdbs.prev_cpu_nice =
 401                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 402
 403         }
 404         return count;
 405 }
 406
 407 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf,
 408                 size_t count)
 409 {
 410         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 411         unsigned int input;
 412         int ret;
 413         ret = sscanf(buf, "%u", &input);
 414
 415         if (ret != 1)
 416                 return -EINVAL;
 417
 418         if (input > 1000)
 419                 input = 1000;
 420
 421         od_tuners->powersave_bias = input;
 422         ondemand_powersave_bias_init();
 423         return count;
 424 }
 425
 426 show_store_one(od, sampling_rate);
 427 show_store_one(od, io_is_busy);
 428 show_store_one(od, up_threshold);
 429 show_store_one(od, sampling_down_factor);
 430 show_store_one(od, ignore_nice_load);
 431 show_store_one(od, powersave_bias);
 432 declare_show_sampling_rate_min(od);
 433
 434 gov_sys_pol_attr_rw(sampling_rate);
 435 gov_sys_pol_attr_rw(io_is_busy);
 436 gov_sys_pol_attr_rw(up_threshold);
 437 gov_sys_pol_attr_rw(sampling_down_factor);
 438 gov_sys_pol_attr_rw(ignore_nice_load);
 439 gov_sys_pol_attr_rw(powersave_bias);
 440 gov_sys_pol_attr_ro(sampling_rate_min);
 441
 442 static struct attribute *dbs_attributes_gov_sys[] = {
 443         &sampling_rate_min_gov_sys.attr,
 444         &sampling_rate_gov_sys.attr,
 445         &up_threshold_gov_sys.attr,
 446         &sampling_down_factor_gov_sys.attr,
 447         &ignore_nice_load_gov_sys.attr,
 448         &powersave_bias_gov_sys.attr,
 449         &io_is_busy_gov_sys.attr,
 450         NULL
 451 };
 452
 453 static struct attribute_group od_attr_group_gov_sys = {
 454         .attrs = dbs_attributes_gov_sys,
 455         .name = "ondemand",
 456 };
 457
 458 static struct attribute *dbs_attributes_gov_pol[] = {
 459         &sampling_rate_min_gov_pol.attr,
 460         &sampling_rate_gov_pol.attr,
 461         &up_threshold_gov_pol.attr,
 462         &sampling_down_factor_gov_pol.attr,
 463         &ignore_nice_load_gov_pol.attr,
 464         &powersave_bias_gov_pol.attr,
 465         &io_is_busy_gov_pol.attr,
 466         NULL
 467 };
 468
 469 static struct attribute_group od_attr_group_gov_pol = {
 470         .attrs = dbs_attributes_gov_pol,
 471         .name = "ondemand",
 472 };
 473
 474 /************************** sysfs end ************************/
 475
 476 static int od_init(struct dbs_data *dbs_data)
 477 {
 478         struct od_dbs_tuners *tuners;
 479         u64 idle_time;
 480         int cpu;
 481
 482         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 483         if (!tuners) {
 484                 pr_err("%s: kzalloc failed\n", __func__);
 485                 return -ENOMEM;
 486         }
 487
 488         cpu = get_cpu();
 489         idle_time = get_cpu_idle_time_us(cpu, NULL);
 490         put_cpu();
 491         if (idle_time != -1ULL) {
 492                 /* Idle micro accounting is supported. Use finer thresholds */
 493                 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 494                 /*
 495                  * In nohz/micro accounting case we set the minimum frequency
 496                  * not depending on HZ, but fixed (very low). The deferred
 497                  * timer might skip some samples if idle/sleeping as needed.
 498                 */
 499                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 500         } else {
 501                 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 502
 503                 /* For correct statistics, we need 10 ticks for each measure */
 504                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 505                         jiffies_to_usecs(10);
 506         }
 507
 508         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 509         tuners->ignore_nice_load = 0;
 510         tuners->powersave_bias = default_powersave_bias;
 511         tuners->io_is_busy = should_io_be_busy();
 512
 513         dbs_data->tuners = tuners;
 514         mutex_init(&dbs_data->mutex);
 515         return 0;
 516 }
 517
 518 static void od_exit(struct dbs_data *dbs_data)
 519 {
 520         kfree(dbs_data->tuners);
 521 }
 522
 523 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 524
 525 static struct od_ops od_ops = {
 526         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 527         .powersave_bias_target = generic_powersave_bias_target,
 528         .freq_increase = dbs_freq_increase,
 529 };
 530
 531 static struct common_dbs_data od_dbs_cdata = {
 532         .governor = GOV_ONDEMAND,
 533         .attr_group_gov_sys = &od_attr_group_gov_sys,
 534         .attr_group_gov_pol = &od_attr_group_gov_pol,
 535         .get_cpu_cdbs = get_cpu_cdbs,
 536         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 537         .gov_dbs_timer = od_dbs_timer,
 538         .gov_check_cpu = od_check_cpu,
 539         .gov_ops = &od_ops,
 540         .init = od_init,
 541         .exit = od_exit,
 542 };
 543
 544 static void od_set_powersave_bias(unsigned int powersave_bias)
 545 {
 546         struct cpufreq_policy *policy;
 547         struct dbs_data *dbs_data;
 548         struct od_dbs_tuners *od_tuners;
 549         unsigned int cpu;
 550         cpumask_t done;
 551
 552         default_powersave_bias = powersave_bias;
 553         cpumask_clear(&done);
 554
 555         get_online_cpus();
 556         for_each_online_cpu(cpu) {
 557                 if (cpumask_test_cpu(cpu, &done))
 558                         continue;
 559
 560                 policy = per_cpu(od_cpu_dbs_info, cpu).cdbs.cur_policy;
 561                 if (!policy)
 562                         continue;
 563
 564                 cpumask_or(&done, &done, policy->cpus);
 565
 566                 if (policy->governor != &cpufreq_gov_ondemand)
 567                         continue;
 568
 569                 dbs_data = policy->governor_data;
 570                 od_tuners = dbs_data->tuners;
 571                 od_tuners->powersave_bias = default_powersave_bias;
 572         }
 573         put_online_cpus();
 574 }
 575
 576 void od_register_powersave_bias_handler(unsigned int (*f)
 577                 (struct cpufreq_policy *, unsigned int, unsigned int),
 578                 unsigned int powersave_bias)
 579 {
 580         od_ops.powersave_bias_target = f;
 581         od_set_powersave_bias(powersave_bias);
 582 }
 583 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 584
 585 void od_unregister_powersave_bias_handler(void)
 586 {
 587         od_ops.powersave_bias_target = generic_powersave_bias_target;
 588         od_set_powersave_bias(0);
 589 }
 590 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 591
 592 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 593                 unsigned int event)
 594 {
 595         return cpufreq_governor_dbs(policy, &od_dbs_cdata, event);
 596 }
 597
 598 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 599 static
 600 #endif
 601 struct cpufreq_governor cpufreq_gov_ondemand = {
 602         .name                   = "ondemand",
 603         .governor               = od_cpufreq_governor_dbs,
 604         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 605         .owner                  = THIS_MODULE,
 606 };
 607
 608 static int __init cpufreq_gov_dbs_init(void)
 609 {
 610         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 611 }
 612
 613 static void __exit cpufreq_gov_dbs_exit(void)
 614 {
 615         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 616 }
 617
 618 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 619 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 620 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 621         "Low Latency Frequency Transition capable processors");
 622 MODULE_LICENSE("GPL");
 623
 624 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 625 fs_initcall(cpufreq_gov_dbs_init);
 626 #else
 627 module_init(cpufreq_gov_dbs_init);
 628 #endif
 629 module_exit(cpufreq_gov_dbs_exit);