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.shared->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         } else {
 172                 /* Calculate the next frequency proportional to load */
 173                 unsigned int freq_next, min_f, max_f;
 174
 175                 min_f = policy->cpuinfo.min_freq;
 176                 max_f = policy->cpuinfo.max_freq;
 177                 freq_next = min_f + load * (max_f - min_f) / 100;
 178
 179                 /* No longer fully busy, reset rate_mult */
 180                 dbs_info->rate_mult = 1;
 181
 182                 if (!od_tuners->powersave_bias) {
 183                         __cpufreq_driver_target(policy, freq_next,
 184                                         CPUFREQ_RELATION_C);
 185                         return;
 186                 }
 187
 188                 freq_next = od_ops.powersave_bias_target(policy, freq_next,
 189                                         CPUFREQ_RELATION_L);
 190                 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
 191         }
 192 }
 193
 194 static unsigned int od_dbs_timer(struct cpu_dbs_info *cdbs,
 195                                  struct dbs_data *dbs_data, bool modify_all)
 196 {
 197         struct cpufreq_policy *policy = cdbs->shared->policy;
 198         unsigned int cpu = policy->cpu;
 199         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 200                         cpu);
 201         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 202         int delay = 0, sample_type = dbs_info->sample_type;
 203
 204         if (!modify_all)
 205                 goto max_delay;
 206
 207         /* Common NORMAL_SAMPLE setup */
 208         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 209         if (sample_type == OD_SUB_SAMPLE) {
 210                 delay = dbs_info->freq_lo_jiffies;
 211                 __cpufreq_driver_target(policy, dbs_info->freq_lo,
 212                                         CPUFREQ_RELATION_H);
 213         } else {
 214                 dbs_check_cpu(dbs_data, cpu);
 215                 if (dbs_info->freq_lo) {
 216                         /* Setup timer for SUB_SAMPLE */
 217                         dbs_info->sample_type = OD_SUB_SAMPLE;
 218                         delay = dbs_info->freq_hi_jiffies;
 219                 }
 220         }
 221
 222 max_delay:
 223         if (!delay)
 224                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 225                                 * dbs_info->rate_mult);
 226
 227         return delay;
 228 }
 229
 230 /************************** sysfs interface ************************/
 231 static struct common_dbs_data od_dbs_cdata;
 232
 233 /**
 234  * update_sampling_rate - update sampling rate effective immediately if needed.
 235  * @new_rate: new sampling rate
 236  *
 237  * If new rate is smaller than the old, simply updating
 238  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 239  * original sampling_rate was 1 second and the requested new sampling rate is 10
 240  * ms because the user needs immediate reaction from ondemand governor, but not
 241  * sure if higher frequency will be required or not, then, the governor may
 242  * change the sampling rate too late; up to 1 second later. Thus, if we are
 243  * reducing the sampling rate, we need to make the new value effective
 244  * immediately.
 245  */
 246 static void update_sampling_rate(struct dbs_data *dbs_data,
 247                 unsigned int new_rate)
 248 {
 249         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 250         int cpu;
 251
 252         od_tuners->sampling_rate = new_rate = max(new_rate,
 253                         dbs_data->min_sampling_rate);
 254
 255         for_each_online_cpu(cpu) {
 256                 struct cpufreq_policy *policy;
 257                 struct od_cpu_dbs_info_s *dbs_info;
 258                 unsigned long next_sampling, appointed_at;
 259
 260                 policy = cpufreq_cpu_get(cpu);
 261                 if (!policy)
 262                         continue;
 263                 if (policy->governor != &cpufreq_gov_ondemand) {
 264                         cpufreq_cpu_put(policy);
 265                         continue;
 266                 }
 267                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 268                 cpufreq_cpu_put(policy);
 269
 270                 mutex_lock(&dbs_info->cdbs.shared->timer_mutex);
 271
 272                 if (!delayed_work_pending(&dbs_info->cdbs.dwork)) {
 273                         mutex_unlock(&dbs_info->cdbs.shared->timer_mutex);
 274                         continue;
 275                 }
 276
 277                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 278                 appointed_at = dbs_info->cdbs.dwork.timer.expires;
 279
 280                 if (time_before(next_sampling, appointed_at)) {
 281
 282                         mutex_unlock(&dbs_info->cdbs.shared->timer_mutex);
 283                         cancel_delayed_work_sync(&dbs_info->cdbs.dwork);
 284                         mutex_lock(&dbs_info->cdbs.shared->timer_mutex);
 285
 286                         gov_queue_work(dbs_data, policy,
 287                                        usecs_to_jiffies(new_rate), true);
 288
 289                 }
 290                 mutex_unlock(&dbs_info->cdbs.shared->timer_mutex);
 291         }
 292 }
 293
 294 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 295                 size_t count)
 296 {
 297         unsigned int input;
 298         int ret;
 299         ret = sscanf(buf, "%u", &input);
 300         if (ret != 1)
 301                 return -EINVAL;
 302
 303         update_sampling_rate(dbs_data, input);
 304         return count;
 305 }
 306
 307 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
 308                 size_t count)
 309 {
 310         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 311         unsigned int input;
 312         int ret;
 313         unsigned int j;
 314
 315         ret = sscanf(buf, "%u", &input);
 316         if (ret != 1)
 317                 return -EINVAL;
 318         od_tuners->io_is_busy = !!input;
 319
 320         /* we need to re-evaluate prev_cpu_idle */
 321         for_each_online_cpu(j) {
 322                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 323                                                                         j);
 324                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 325                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 326         }
 327         return count;
 328 }
 329
 330 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 331                 size_t count)
 332 {
 333         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 334         unsigned int input;
 335         int ret;
 336         ret = sscanf(buf, "%u", &input);
 337
 338         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 339                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 340                 return -EINVAL;
 341         }
 342
 343         od_tuners->up_threshold = input;
 344         return count;
 345 }
 346
 347 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 348                 const char *buf, size_t count)
 349 {
 350         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 351         unsigned int input, j;
 352         int ret;
 353         ret = sscanf(buf, "%u", &input);
 354
 355         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 356                 return -EINVAL;
 357         od_tuners->sampling_down_factor = input;
 358
 359         /* Reset down sampling multiplier in case it was active */
 360         for_each_online_cpu(j) {
 361                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 362                                 j);
 363                 dbs_info->rate_mult = 1;
 364         }
 365         return count;
 366 }
 367
 368 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 369                 const char *buf, size_t count)
 370 {
 371         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 372         unsigned int input;
 373         int ret;
 374
 375         unsigned int j;
 376
 377         ret = sscanf(buf, "%u", &input);
 378         if (ret != 1)
 379                 return -EINVAL;
 380
 381         if (input > 1)
 382                 input = 1;
 383
 384         if (input == od_tuners->ignore_nice_load) { /* nothing to do */
 385                 return count;
 386         }
 387         od_tuners->ignore_nice_load = input;
 388
 389         /* we need to re-evaluate prev_cpu_idle */
 390         for_each_online_cpu(j) {
 391                 struct od_cpu_dbs_info_s *dbs_info;
 392                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 393                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 394                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 395                 if (od_tuners->ignore_nice_load)
 396                         dbs_info->cdbs.prev_cpu_nice =
 397                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 398
 399         }
 400         return count;
 401 }
 402
 403 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf,
 404                 size_t count)
 405 {
 406         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 407         unsigned int input;
 408         int ret;
 409         ret = sscanf(buf, "%u", &input);
 410
 411         if (ret != 1)
 412                 return -EINVAL;
 413
 414         if (input > 1000)
 415                 input = 1000;
 416
 417         od_tuners->powersave_bias = input;
 418         ondemand_powersave_bias_init();
 419         return count;
 420 }
 421
 422 show_store_one(od, sampling_rate);
 423 show_store_one(od, io_is_busy);
 424 show_store_one(od, up_threshold);
 425 show_store_one(od, sampling_down_factor);
 426 show_store_one(od, ignore_nice_load);
 427 show_store_one(od, powersave_bias);
 428 declare_show_sampling_rate_min(od);
 429
 430 gov_sys_pol_attr_rw(sampling_rate);
 431 gov_sys_pol_attr_rw(io_is_busy);
 432 gov_sys_pol_attr_rw(up_threshold);
 433 gov_sys_pol_attr_rw(sampling_down_factor);
 434 gov_sys_pol_attr_rw(ignore_nice_load);
 435 gov_sys_pol_attr_rw(powersave_bias);
 436 gov_sys_pol_attr_ro(sampling_rate_min);
 437
 438 static struct attribute *dbs_attributes_gov_sys[] = {
 439         &sampling_rate_min_gov_sys.attr,
 440         &sampling_rate_gov_sys.attr,
 441         &up_threshold_gov_sys.attr,
 442         &sampling_down_factor_gov_sys.attr,
 443         &ignore_nice_load_gov_sys.attr,
 444         &powersave_bias_gov_sys.attr,
 445         &io_is_busy_gov_sys.attr,
 446         NULL
 447 };
 448
 449 static struct attribute_group od_attr_group_gov_sys = {
 450         .attrs = dbs_attributes_gov_sys,
 451         .name = "ondemand",
 452 };
 453
 454 static struct attribute *dbs_attributes_gov_pol[] = {
 455         &sampling_rate_min_gov_pol.attr,
 456         &sampling_rate_gov_pol.attr,
 457         &up_threshold_gov_pol.attr,
 458         &sampling_down_factor_gov_pol.attr,
 459         &ignore_nice_load_gov_pol.attr,
 460         &powersave_bias_gov_pol.attr,
 461         &io_is_busy_gov_pol.attr,
 462         NULL
 463 };
 464
 465 static struct attribute_group od_attr_group_gov_pol = {
 466         .attrs = dbs_attributes_gov_pol,
 467         .name = "ondemand",
 468 };
 469
 470 /************************** sysfs end ************************/
 471
 472 static int od_init(struct dbs_data *dbs_data, bool notify)
 473 {
 474         struct od_dbs_tuners *tuners;
 475         u64 idle_time;
 476         int cpu;
 477
 478         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 479         if (!tuners) {
 480                 pr_err("%s: kzalloc failed\n", __func__);
 481                 return -ENOMEM;
 482         }
 483
 484         cpu = get_cpu();
 485         idle_time = get_cpu_idle_time_us(cpu, NULL);
 486         put_cpu();
 487         if (idle_time != -1ULL) {
 488                 /* Idle micro accounting is supported. Use finer thresholds */
 489                 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 490                 /*
 491                  * In nohz/micro accounting case we set the minimum frequency
 492                  * not depending on HZ, but fixed (very low). The deferred
 493                  * timer might skip some samples if idle/sleeping as needed.
 494                 */
 495                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 496         } else {
 497                 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 498
 499                 /* For correct statistics, we need 10 ticks for each measure */
 500                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 501                         jiffies_to_usecs(10);
 502         }
 503
 504         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 505         tuners->ignore_nice_load = 0;
 506         tuners->powersave_bias = default_powersave_bias;
 507         tuners->io_is_busy = should_io_be_busy();
 508
 509         dbs_data->tuners = tuners;
 510         return 0;
 511 }
 512
 513 static void od_exit(struct dbs_data *dbs_data, bool notify)
 514 {
 515         kfree(dbs_data->tuners);
 516 }
 517
 518 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 519
 520 static struct od_ops od_ops = {
 521         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 522         .powersave_bias_target = generic_powersave_bias_target,
 523         .freq_increase = dbs_freq_increase,
 524 };
 525
 526 static struct common_dbs_data od_dbs_cdata = {
 527         .governor = GOV_ONDEMAND,
 528         .attr_group_gov_sys = &od_attr_group_gov_sys,
 529         .attr_group_gov_pol = &od_attr_group_gov_pol,
 530         .get_cpu_cdbs = get_cpu_cdbs,
 531         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 532         .gov_dbs_timer = od_dbs_timer,
 533         .gov_check_cpu = od_check_cpu,
 534         .gov_ops = &od_ops,
 535         .init = od_init,
 536         .exit = od_exit,
 537         .mutex = __MUTEX_INITIALIZER(od_dbs_cdata.mutex),
 538 };
 539
 540 static void od_set_powersave_bias(unsigned int powersave_bias)
 541 {
 542         struct cpufreq_policy *policy;
 543         struct dbs_data *dbs_data;
 544         struct od_dbs_tuners *od_tuners;
 545         unsigned int cpu;
 546         cpumask_t done;
 547
 548         default_powersave_bias = powersave_bias;
 549         cpumask_clear(&done);
 550
 551         get_online_cpus();
 552         for_each_online_cpu(cpu) {
 553                 struct cpu_common_dbs_info *shared;
 554
 555                 if (cpumask_test_cpu(cpu, &done))
 556                         continue;
 557
 558                 shared = per_cpu(od_cpu_dbs_info, cpu).cdbs.shared;
 559                 if (!shared)
 560                         continue;
 561
 562                 policy = shared->policy;
 563                 cpumask_or(&done, &done, policy->cpus);
 564
 565                 if (policy->governor != &cpufreq_gov_ondemand)
 566                         continue;
 567
 568                 dbs_data = policy->governor_data;
 569                 od_tuners = dbs_data->tuners;
 570                 od_tuners->powersave_bias = default_powersave_bias;
 571         }
 572         put_online_cpus();
 573 }
 574
 575 void od_register_powersave_bias_handler(unsigned int (*f)
 576                 (struct cpufreq_policy *, unsigned int, unsigned int),
 577                 unsigned int powersave_bias)
 578 {
 579         od_ops.powersave_bias_target = f;
 580         od_set_powersave_bias(powersave_bias);
 581 }
 582 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 583
 584 void od_unregister_powersave_bias_handler(void)
 585 {
 586         od_ops.powersave_bias_target = generic_powersave_bias_target;
 587         od_set_powersave_bias(0);
 588 }
 589 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 590
 591 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 592                 unsigned int event)
 593 {
 594         return cpufreq_governor_dbs(policy, &od_dbs_cdata, event);
 595 }
 596
 597 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 598 static
 599 #endif
 600 struct cpufreq_governor cpufreq_gov_ondemand = {
 601         .name                   = "ondemand",
 602         .governor               = od_cpufreq_governor_dbs,
 603         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 604         .owner                  = THIS_MODULE,
 605 };
 606
 607 static int __init cpufreq_gov_dbs_init(void)
 608 {
 609         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 610 }
 611
 612 static void __exit cpufreq_gov_dbs_exit(void)
 613 {
 614         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 615 }
 616
 617 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 618 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 619 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 620         "Low Latency Frequency Transition capable processors");
 621 MODULE_LICENSE("GPL");
 622
 623 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 624 fs_initcall(cpufreq_gov_dbs_init);
 625 #else
 626 module_init(cpufreq_gov_dbs_init);
 627 #endif
 628 module_exit(cpufreq_gov_dbs_exit);