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 (freq_next < policy->min)
 181                         freq_next = policy->min;
 182
 183                 if (!od_tuners->powersave_bias) {
 184                         __cpufreq_driver_target(policy, freq_next,
 185                                         CPUFREQ_RELATION_L);
 186                         return;
 187                 }
 188
 189                 freq_next = od_ops.powersave_bias_target(policy, freq_next,
 190                                         CPUFREQ_RELATION_L);
 191                 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
 192         }
 193 }
 194
 195 static void od_dbs_timer(struct work_struct *work)
 196 {
 197         struct od_cpu_dbs_info_s *dbs_info =
 198                 container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
 199         unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 200         struct od_cpu_dbs_info_s *core_dbs_info = &per_cpu(od_cpu_dbs_info,
 201                         cpu);
 202         struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data;
 203         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 204         int delay = 0, sample_type = core_dbs_info->sample_type;
 205         bool modify_all = true;
 206
 207         mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 208         if (!need_load_eval(&core_dbs_info->cdbs, od_tuners->sampling_rate)) {
 209                 modify_all = false;
 210                 goto max_delay;
 211         }
 212
 213         /* Common NORMAL_SAMPLE setup */
 214         core_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 215         if (sample_type == OD_SUB_SAMPLE) {
 216                 delay = core_dbs_info->freq_lo_jiffies;
 217                 __cpufreq_driver_target(core_dbs_info->cdbs.cur_policy,
 218                                 core_dbs_info->freq_lo, CPUFREQ_RELATION_H);
 219         } else {
 220                 dbs_check_cpu(dbs_data, cpu);
 221                 if (core_dbs_info->freq_lo) {
 222                         /* Setup timer for SUB_SAMPLE */
 223                         core_dbs_info->sample_type = OD_SUB_SAMPLE;
 224                         delay = core_dbs_info->freq_hi_jiffies;
 225                 }
 226         }
 227
 228 max_delay:
 229         if (!delay)
 230                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 231                                 * core_dbs_info->rate_mult);
 232
 233         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all);
 234         mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 235 }
 236
 237 /************************** sysfs interface ************************/
 238 static struct common_dbs_data od_dbs_cdata;
 239
 240 /**
 241  * update_sampling_rate - update sampling rate effective immediately if needed.
 242  * @new_rate: new sampling rate
 243  *
 244  * If new rate is smaller than the old, simply updating
 245  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 246  * original sampling_rate was 1 second and the requested new sampling rate is 10
 247  * ms because the user needs immediate reaction from ondemand governor, but not
 248  * sure if higher frequency will be required or not, then, the governor may
 249  * change the sampling rate too late; up to 1 second later. Thus, if we are
 250  * reducing the sampling rate, we need to make the new value effective
 251  * immediately.
 252  */
 253 static void update_sampling_rate(struct dbs_data *dbs_data,
 254                 unsigned int new_rate)
 255 {
 256         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 257         int cpu;
 258
 259         od_tuners->sampling_rate = new_rate = max(new_rate,
 260                         dbs_data->min_sampling_rate);
 261
 262         for_each_online_cpu(cpu) {
 263                 struct cpufreq_policy *policy;
 264                 struct od_cpu_dbs_info_s *dbs_info;
 265                 unsigned long next_sampling, appointed_at;
 266
 267                 policy = cpufreq_cpu_get(cpu);
 268                 if (!policy)
 269                         continue;
 270                 if (policy->governor != &cpufreq_gov_ondemand) {
 271                         cpufreq_cpu_put(policy);
 272                         continue;
 273                 }
 274                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 275                 cpufreq_cpu_put(policy);
 276
 277                 mutex_lock(&dbs_info->cdbs.timer_mutex);
 278
 279                 if (!delayed_work_pending(&dbs_info->cdbs.work)) {
 280                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 281                         continue;
 282                 }
 283
 284                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 285                 appointed_at = dbs_info->cdbs.work.timer.expires;
 286
 287                 if (time_before(next_sampling, appointed_at)) {
 288
 289                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 290                         cancel_delayed_work_sync(&dbs_info->cdbs.work);
 291                         mutex_lock(&dbs_info->cdbs.timer_mutex);
 292
 293                         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy,
 294                                         usecs_to_jiffies(new_rate), true);
 295
 296                 }
 297                 mutex_unlock(&dbs_info->cdbs.timer_mutex);
 298         }
 299 }
 300
 301 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 302                 size_t count)
 303 {
 304         unsigned int input;
 305         int ret;
 306         ret = sscanf(buf, "%u", &input);
 307         if (ret != 1)
 308                 return -EINVAL;
 309
 310         update_sampling_rate(dbs_data, input);
 311         return count;
 312 }
 313
 314 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
 315                 size_t count)
 316 {
 317         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 318         unsigned int input;
 319         int ret;
 320         unsigned int j;
 321
 322         ret = sscanf(buf, "%u", &input);
 323         if (ret != 1)
 324                 return -EINVAL;
 325         od_tuners->io_is_busy = !!input;
 326
 327         /* we need to re-evaluate prev_cpu_idle */
 328         for_each_online_cpu(j) {
 329                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 330                                                                         j);
 331                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 332                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 333         }
 334         return count;
 335 }
 336
 337 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 338                 size_t count)
 339 {
 340         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 341         unsigned int input;
 342         int ret;
 343         ret = sscanf(buf, "%u", &input);
 344
 345         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 346                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 347                 return -EINVAL;
 348         }
 349
 350         od_tuners->up_threshold = input;
 351         return count;
 352 }
 353
 354 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 355                 const char *buf, size_t count)
 356 {
 357         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 358         unsigned int input, j;
 359         int ret;
 360         ret = sscanf(buf, "%u", &input);
 361
 362         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 363                 return -EINVAL;
 364         od_tuners->sampling_down_factor = input;
 365
 366         /* Reset down sampling multiplier in case it was active */
 367         for_each_online_cpu(j) {
 368                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 369                                 j);
 370                 dbs_info->rate_mult = 1;
 371         }
 372         return count;
 373 }
 374
 375 static ssize_t store_ignore_nice(struct dbs_data *dbs_data, const char *buf,
 376                 size_t count)
 377 {
 378         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 379         unsigned int input;
 380         int ret;
 381
 382         unsigned int j;
 383
 384         ret = sscanf(buf, "%u", &input);
 385         if (ret != 1)
 386                 return -EINVAL;
 387
 388         if (input > 1)
 389                 input = 1;
 390
 391         if (input == od_tuners->ignore_nice) { /* nothing to do */
 392                 return count;
 393         }
 394         od_tuners->ignore_nice = input;
 395
 396         /* we need to re-evaluate prev_cpu_idle */
 397         for_each_online_cpu(j) {
 398                 struct od_cpu_dbs_info_s *dbs_info;
 399                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 400                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 401                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 402                 if (od_tuners->ignore_nice)
 403                         dbs_info->cdbs.prev_cpu_nice =
 404                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 405
 406         }
 407         return count;
 408 }
 409
 410 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf,
 411                 size_t count)
 412 {
 413         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 414         unsigned int input;
 415         int ret;
 416         ret = sscanf(buf, "%u", &input);
 417
 418         if (ret != 1)
 419                 return -EINVAL;
 420
 421         if (input > 1000)
 422                 input = 1000;
 423
 424         od_tuners->powersave_bias = input;
 425         ondemand_powersave_bias_init();
 426         return count;
 427 }
 428
 429 show_store_one(od, sampling_rate);
 430 show_store_one(od, io_is_busy);
 431 show_store_one(od, up_threshold);
 432 show_store_one(od, sampling_down_factor);
 433 show_store_one(od, ignore_nice);
 434 show_store_one(od, powersave_bias);
 435 declare_show_sampling_rate_min(od);
 436
 437 gov_sys_pol_attr_rw(sampling_rate);
 438 gov_sys_pol_attr_rw(io_is_busy);
 439 gov_sys_pol_attr_rw(up_threshold);
 440 gov_sys_pol_attr_rw(sampling_down_factor);
 441 gov_sys_pol_attr_rw(ignore_nice);
 442 gov_sys_pol_attr_rw(powersave_bias);
 443 gov_sys_pol_attr_ro(sampling_rate_min);
 444
 445 static struct attribute *dbs_attributes_gov_sys[] = {
 446         &sampling_rate_min_gov_sys.attr,
 447         &sampling_rate_gov_sys.attr,
 448         &up_threshold_gov_sys.attr,
 449         &sampling_down_factor_gov_sys.attr,
 450         &ignore_nice_gov_sys.attr,
 451         &powersave_bias_gov_sys.attr,
 452         &io_is_busy_gov_sys.attr,
 453         NULL
 454 };
 455
 456 static struct attribute_group od_attr_group_gov_sys = {
 457         .attrs = dbs_attributes_gov_sys,
 458         .name = "ondemand",
 459 };
 460
 461 static struct attribute *dbs_attributes_gov_pol[] = {
 462         &sampling_rate_min_gov_pol.attr,
 463         &sampling_rate_gov_pol.attr,
 464         &up_threshold_gov_pol.attr,
 465         &sampling_down_factor_gov_pol.attr,
 466         &ignore_nice_gov_pol.attr,
 467         &powersave_bias_gov_pol.attr,
 468         &io_is_busy_gov_pol.attr,
 469         NULL
 470 };
 471
 472 static struct attribute_group od_attr_group_gov_pol = {
 473         .attrs = dbs_attributes_gov_pol,
 474         .name = "ondemand",
 475 };
 476
 477 /************************** sysfs end ************************/
 478
 479 static int od_init(struct dbs_data *dbs_data)
 480 {
 481         struct od_dbs_tuners *tuners;
 482         u64 idle_time;
 483         int cpu;
 484
 485         tuners = kzalloc(sizeof(struct od_dbs_tuners), GFP_KERNEL);
 486         if (!tuners) {
 487                 pr_err("%s: kzalloc failed\n", __func__);
 488                 return -ENOMEM;
 489         }
 490
 491         cpu = get_cpu();
 492         idle_time = get_cpu_idle_time_us(cpu, NULL);
 493         put_cpu();
 494         if (idle_time != -1ULL) {
 495                 /* Idle micro accounting is supported. Use finer thresholds */
 496                 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 497                 /*
 498                  * In nohz/micro accounting case we set the minimum frequency
 499                  * not depending on HZ, but fixed (very low). The deferred
 500                  * timer might skip some samples if idle/sleeping as needed.
 501                 */
 502                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 503         } else {
 504                 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 505
 506                 /* For correct statistics, we need 10 ticks for each measure */
 507                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 508                         jiffies_to_usecs(10);
 509         }
 510
 511         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 512         tuners->ignore_nice = 0;
 513         tuners->powersave_bias = default_powersave_bias;
 514         tuners->io_is_busy = should_io_be_busy();
 515
 516         dbs_data->tuners = tuners;
 517         mutex_init(&dbs_data->mutex);
 518         return 0;
 519 }
 520
 521 static void od_exit(struct dbs_data *dbs_data)
 522 {
 523         kfree(dbs_data->tuners);
 524 }
 525
 526 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 527
 528 static struct od_ops od_ops = {
 529         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 530         .powersave_bias_target = generic_powersave_bias_target,
 531         .freq_increase = dbs_freq_increase,
 532 };
 533
 534 static struct common_dbs_data od_dbs_cdata = {
 535         .governor = GOV_ONDEMAND,
 536         .attr_group_gov_sys = &od_attr_group_gov_sys,
 537         .attr_group_gov_pol = &od_attr_group_gov_pol,
 538         .get_cpu_cdbs = get_cpu_cdbs,
 539         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 540         .gov_dbs_timer = od_dbs_timer,
 541         .gov_check_cpu = od_check_cpu,
 542         .gov_ops = &od_ops,
 543         .init = od_init,
 544         .exit = od_exit,
 545 };
 546
 547 static void od_set_powersave_bias(unsigned int powersave_bias)
 548 {
 549         struct cpufreq_policy *policy;
 550         struct dbs_data *dbs_data;
 551         struct od_dbs_tuners *od_tuners;
 552         unsigned int cpu;
 553         cpumask_t done;
 554
 555         default_powersave_bias = powersave_bias;
 556         cpumask_clear(&done);
 557
 558         get_online_cpus();
 559         for_each_online_cpu(cpu) {
 560                 if (cpumask_test_cpu(cpu, &done))
 561                         continue;
 562
 563                 policy = per_cpu(od_cpu_dbs_info, cpu).cdbs.cur_policy;
 564                 if (!policy)
 565                         continue;
 566
 567                 cpumask_or(&done, &done, policy->cpus);
 568
 569                 if (policy->governor != &cpufreq_gov_ondemand)
 570                         continue;
 571
 572                 dbs_data = policy->governor_data;
 573                 od_tuners = dbs_data->tuners;
 574                 od_tuners->powersave_bias = default_powersave_bias;
 575         }
 576         put_online_cpus();
 577 }
 578
 579 void od_register_powersave_bias_handler(unsigned int (*f)
 580                 (struct cpufreq_policy *, unsigned int, unsigned int),
 581                 unsigned int powersave_bias)
 582 {
 583         od_ops.powersave_bias_target = f;
 584         od_set_powersave_bias(powersave_bias);
 585 }
 586 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 587
 588 void od_unregister_powersave_bias_handler(void)
 589 {
 590         od_ops.powersave_bias_target = generic_powersave_bias_target;
 591         od_set_powersave_bias(0);
 592 }
 593 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 594
 595 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 596                 unsigned int event)
 597 {
 598         return cpufreq_governor_dbs(policy, &od_dbs_cdata, event);
 599 }
 600
 601 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 602 static
 603 #endif
 604 struct cpufreq_governor cpufreq_gov_ondemand = {
 605         .name                   = "ondemand",
 606         .governor               = od_cpufreq_governor_dbs,
 607         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 608         .owner                  = THIS_MODULE,
 609 };
 610
 611 static int __init cpufreq_gov_dbs_init(void)
 612 {
 613         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 614 }
 615
 616 static void __exit cpufreq_gov_dbs_exit(void)
 617 {
 618         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 619 }
 620
 621 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 622 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 623 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 624         "Low Latency Frequency Transition capable processors");
 625 MODULE_LICENSE("GPL");
 626
 627 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 628 fs_initcall(cpufreq_gov_dbs_init);
 629 #else
 630 module_init(cpufreq_gov_dbs_init);
 631 #endif
 632 module_exit(cpufreq_gov_dbs_exit);