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 static struct cpufreq_governor cpufreq_gov_ondemand;
  35
  36 static unsigned int default_powersave_bias;
  37
  38 static void ondemand_powersave_bias_init_cpu(int cpu)
  39 {
  40         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
  41
  42         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
  43         dbs_info->freq_lo = 0;
  44 }
  45
  46 /*
  47  * Not all CPUs want IO time to be accounted as busy; this depends on how
  48  * efficient idling at a higher frequency/voltage is.
  49  * Pavel Machek says this is not so for various generations of AMD and old
  50  * Intel systems.
  51  * Mike Chan (android.com) claims this is also not true for ARM.
  52  * Because of this, whitelist specific known (series) of CPUs by default, and
  53  * leave all others up to the user.
  54  */
  55 static int should_io_be_busy(void)
  56 {
  57 #if defined(CONFIG_X86)
  58         /*
  59          * For Intel, Core 2 (model 15) and later have an efficient idle.
  60          */
  61         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  62                         boot_cpu_data.x86 == 6 &&
  63                         boot_cpu_data.x86_model >= 15)
  64                 return 1;
  65 #endif
  66         return 0;
  67 }
  68
  69 /*
  70  * Find right freq to be set now with powersave_bias on.
  71  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
  72  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
  73  */
  74 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
  75                 unsigned int freq_next, unsigned int relation)
  76 {
  77         unsigned int freq_req, freq_reduc, freq_avg;
  78         unsigned int freq_hi, freq_lo;
  79         unsigned int index = 0;
  80         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
  81         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
  82                                                    policy->cpu);
  83         struct dbs_data *dbs_data = policy->governor_data;
  84         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  85
  86         if (!dbs_info->freq_table) {
  87                 dbs_info->freq_lo = 0;
  88                 dbs_info->freq_lo_jiffies = 0;
  89                 return freq_next;
  90         }
  91
  92         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
  93                         relation, &index);
  94         freq_req = dbs_info->freq_table[index].frequency;
  95         freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
  96         freq_avg = freq_req - freq_reduc;
  97
  98         /* Find freq bounds for freq_avg in freq_table */
  99         index = 0;
 100         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 101                         CPUFREQ_RELATION_H, &index);
 102         freq_lo = dbs_info->freq_table[index].frequency;
 103         index = 0;
 104         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 105                         CPUFREQ_RELATION_L, &index);
 106         freq_hi = dbs_info->freq_table[index].frequency;
 107
 108         /* Find out how long we have to be in hi and lo freqs */
 109         if (freq_hi == freq_lo) {
 110                 dbs_info->freq_lo = 0;
 111                 dbs_info->freq_lo_jiffies = 0;
 112                 return freq_lo;
 113         }
 114         jiffies_total = usecs_to_jiffies(od_tuners->sampling_rate);
 115         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 116         jiffies_hi += ((freq_hi - freq_lo) / 2);
 117         jiffies_hi /= (freq_hi - freq_lo);
 118         jiffies_lo = jiffies_total - jiffies_hi;
 119         dbs_info->freq_lo = freq_lo;
 120         dbs_info->freq_lo_jiffies = jiffies_lo;
 121         dbs_info->freq_hi_jiffies = jiffies_hi;
 122         return freq_hi;
 123 }
 124
 125 static void ondemand_powersave_bias_init(void)
 126 {
 127         int i;
 128         for_each_online_cpu(i) {
 129                 ondemand_powersave_bias_init_cpu(i);
 130         }
 131 }
 132
 133 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
 134 {
 135         struct dbs_data *dbs_data = policy->governor_data;
 136         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 137
 138         if (od_tuners->powersave_bias)
 139                 freq = od_ops.powersave_bias_target(policy, freq,
 140                                 CPUFREQ_RELATION_H);
 141         else if (policy->cur == policy->max)
 142                 return;
 143
 144         __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
 145                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 146 }
 147
 148 /*
 149  * Every sampling_rate, we check, if current idle time is less than 20%
 150  * (default), then we try to increase frequency. Else, we adjust the frequency
 151  * proportional to load.
 152  */
 153 static void od_check_cpu(int cpu, unsigned int load)
 154 {
 155         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 156         struct cpufreq_policy *policy = dbs_info->cdbs.shared->policy;
 157         struct dbs_data *dbs_data = policy->governor_data;
 158         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 159
 160         dbs_info->freq_lo = 0;
 161
 162         /* Check for frequency increase */
 163         if (load > od_tuners->up_threshold) {
 164                 /* If switching to max speed, apply sampling_down_factor */
 165                 if (policy->cur < policy->max)
 166                         dbs_info->rate_mult =
 167                                 od_tuners->sampling_down_factor;
 168                 dbs_freq_increase(policy, policy->max);
 169         } else {
 170                 /* Calculate the next frequency proportional to load */
 171                 unsigned int freq_next, min_f, max_f;
 172
 173                 min_f = policy->cpuinfo.min_freq;
 174                 max_f = policy->cpuinfo.max_freq;
 175                 freq_next = min_f + load * (max_f - min_f) / 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_C);
 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_C);
 189         }
 190 }
 191
 192 static unsigned int od_dbs_timer(struct cpufreq_policy *policy, bool modify_all)
 193 {
 194         struct dbs_data *dbs_data = policy->governor_data;
 195         unsigned int cpu = policy->cpu;
 196         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 197                         cpu);
 198         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 199         int delay = 0, sample_type = dbs_info->sample_type;
 200
 201         if (!modify_all)
 202                 goto max_delay;
 203
 204         /* Common NORMAL_SAMPLE setup */
 205         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 206         if (sample_type == OD_SUB_SAMPLE) {
 207                 delay = dbs_info->freq_lo_jiffies;
 208                 __cpufreq_driver_target(policy, dbs_info->freq_lo,
 209                                         CPUFREQ_RELATION_H);
 210         } else {
 211                 dbs_check_cpu(dbs_data, cpu);
 212                 if (dbs_info->freq_lo) {
 213                         /* Setup timer for SUB_SAMPLE */
 214                         dbs_info->sample_type = OD_SUB_SAMPLE;
 215                         delay = dbs_info->freq_hi_jiffies;
 216                 }
 217         }
 218
 219 max_delay:
 220         if (!delay)
 221                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 222                                 * dbs_info->rate_mult);
 223
 224         return delay;
 225 }
 226
 227 /************************** sysfs interface ************************/
 228 static struct common_dbs_data od_dbs_cdata;
 229
 230 /**
 231  * update_sampling_rate - update sampling rate effective immediately if needed.
 232  * @new_rate: new sampling rate
 233  *
 234  * If new rate is smaller than the old, simply updating
 235  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 236  * original sampling_rate was 1 second and the requested new sampling rate is 10
 237  * ms because the user needs immediate reaction from ondemand governor, but not
 238  * sure if higher frequency will be required or not, then, the governor may
 239  * change the sampling rate too late; up to 1 second later. Thus, if we are
 240  * reducing the sampling rate, we need to make the new value effective
 241  * immediately.
 242  */
 243 static void update_sampling_rate(struct dbs_data *dbs_data,
 244                 unsigned int new_rate)
 245 {
 246         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 247         struct cpumask cpumask;
 248         int cpu;
 249
 250         od_tuners->sampling_rate = new_rate = max(new_rate,
 251                         dbs_data->min_sampling_rate);
 252
 253         /*
 254          * Lock governor so that governor start/stop can't execute in parallel.
 255          */
 256         mutex_lock(&od_dbs_cdata.mutex);
 257
 258         cpumask_copy(&cpumask, cpu_online_mask);
 259
 260         for_each_cpu(cpu, &cpumask) {
 261                 struct cpufreq_policy *policy;
 262                 struct od_cpu_dbs_info_s *dbs_info;
 263                 struct cpu_dbs_info *cdbs;
 264                 struct cpu_common_dbs_info *shared;
 265                 unsigned long next_sampling, appointed_at;
 266
 267                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 268                 cdbs = &dbs_info->cdbs;
 269                 shared = cdbs->shared;
 270
 271                 /*
 272                  * A valid shared and shared->policy means governor hasn't
 273                  * stopped or exited yet.
 274                  */
 275                 if (!shared || !shared->policy)
 276                         continue;
 277
 278                 policy = shared->policy;
 279
 280                 /* clear all CPUs of this policy */
 281                 cpumask_andnot(&cpumask, &cpumask, policy->cpus);
 282
 283                 /*
 284                  * Update sampling rate for CPUs whose policy is governed by
 285                  * dbs_data. In case of governor_per_policy, only a single
 286                  * policy will be governed by dbs_data, otherwise there can be
 287                  * multiple policies that are governed by the same dbs_data.
 288                  */
 289                 if (dbs_data != policy->governor_data)
 290                         continue;
 291
 292                 /*
 293                  * Checking this for any CPU should be fine, timers for all of
 294                  * them are scheduled together.
 295                  */
 296                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 297                 appointed_at = dbs_info->cdbs.timer.expires;
 298
 299                 if (time_before(next_sampling, appointed_at)) {
 300                         gov_cancel_work(shared);
 301                         gov_add_timers(policy, usecs_to_jiffies(new_rate));
 302
 303                 }
 304         }
 305
 306         mutex_unlock(&od_dbs_cdata.mutex);
 307 }
 308
 309 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 310                 size_t count)
 311 {
 312         unsigned int input;
 313         int ret;
 314         ret = sscanf(buf, "%u", &input);
 315         if (ret != 1)
 316                 return -EINVAL;
 317
 318         update_sampling_rate(dbs_data, input);
 319         return count;
 320 }
 321
 322 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
 323                 size_t count)
 324 {
 325         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 326         unsigned int input;
 327         int ret;
 328         unsigned int j;
 329
 330         ret = sscanf(buf, "%u", &input);
 331         if (ret != 1)
 332                 return -EINVAL;
 333         od_tuners->io_is_busy = !!input;
 334
 335         /* we need to re-evaluate prev_cpu_idle */
 336         for_each_online_cpu(j) {
 337                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 338                                                                         j);
 339                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 340                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 341         }
 342         return count;
 343 }
 344
 345 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 346                 size_t count)
 347 {
 348         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 349         unsigned int input;
 350         int ret;
 351         ret = sscanf(buf, "%u", &input);
 352
 353         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 354                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 355                 return -EINVAL;
 356         }
 357
 358         od_tuners->up_threshold = input;
 359         return count;
 360 }
 361
 362 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 363                 const char *buf, size_t count)
 364 {
 365         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 366         unsigned int input, j;
 367         int ret;
 368         ret = sscanf(buf, "%u", &input);
 369
 370         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 371                 return -EINVAL;
 372         od_tuners->sampling_down_factor = input;
 373
 374         /* Reset down sampling multiplier in case it was active */
 375         for_each_online_cpu(j) {
 376                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 377                                 j);
 378                 dbs_info->rate_mult = 1;
 379         }
 380         return count;
 381 }
 382
 383 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 384                 const char *buf, size_t count)
 385 {
 386         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 387         unsigned int input;
 388         int ret;
 389
 390         unsigned int j;
 391
 392         ret = sscanf(buf, "%u", &input);
 393         if (ret != 1)
 394                 return -EINVAL;
 395
 396         if (input > 1)
 397                 input = 1;
 398
 399         if (input == od_tuners->ignore_nice_load) { /* nothing to do */
 400                 return count;
 401         }
 402         od_tuners->ignore_nice_load = input;
 403
 404         /* we need to re-evaluate prev_cpu_idle */
 405         for_each_online_cpu(j) {
 406                 struct od_cpu_dbs_info_s *dbs_info;
 407                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 408                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 409                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 410                 if (od_tuners->ignore_nice_load)
 411                         dbs_info->cdbs.prev_cpu_nice =
 412                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 413
 414         }
 415         return count;
 416 }
 417
 418 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf,
 419                 size_t count)
 420 {
 421         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 422         unsigned int input;
 423         int ret;
 424         ret = sscanf(buf, "%u", &input);
 425
 426         if (ret != 1)
 427                 return -EINVAL;
 428
 429         if (input > 1000)
 430                 input = 1000;
 431
 432         od_tuners->powersave_bias = input;
 433         ondemand_powersave_bias_init();
 434         return count;
 435 }
 436
 437 show_store_one(od, sampling_rate);
 438 show_store_one(od, io_is_busy);
 439 show_store_one(od, up_threshold);
 440 show_store_one(od, sampling_down_factor);
 441 show_store_one(od, ignore_nice_load);
 442 show_store_one(od, powersave_bias);
 443 declare_show_sampling_rate_min(od);
 444
 445 gov_sys_pol_attr_rw(sampling_rate);
 446 gov_sys_pol_attr_rw(io_is_busy);
 447 gov_sys_pol_attr_rw(up_threshold);
 448 gov_sys_pol_attr_rw(sampling_down_factor);
 449 gov_sys_pol_attr_rw(ignore_nice_load);
 450 gov_sys_pol_attr_rw(powersave_bias);
 451 gov_sys_pol_attr_ro(sampling_rate_min);
 452
 453 static struct attribute *dbs_attributes_gov_sys[] = {
 454         &sampling_rate_min_gov_sys.attr,
 455         &sampling_rate_gov_sys.attr,
 456         &up_threshold_gov_sys.attr,
 457         &sampling_down_factor_gov_sys.attr,
 458         &ignore_nice_load_gov_sys.attr,
 459         &powersave_bias_gov_sys.attr,
 460         &io_is_busy_gov_sys.attr,
 461         NULL
 462 };
 463
 464 static struct attribute_group od_attr_group_gov_sys = {
 465         .attrs = dbs_attributes_gov_sys,
 466         .name = "ondemand",
 467 };
 468
 469 static struct attribute *dbs_attributes_gov_pol[] = {
 470         &sampling_rate_min_gov_pol.attr,
 471         &sampling_rate_gov_pol.attr,
 472         &up_threshold_gov_pol.attr,
 473         &sampling_down_factor_gov_pol.attr,
 474         &ignore_nice_load_gov_pol.attr,
 475         &powersave_bias_gov_pol.attr,
 476         &io_is_busy_gov_pol.attr,
 477         NULL
 478 };
 479
 480 static struct attribute_group od_attr_group_gov_pol = {
 481         .attrs = dbs_attributes_gov_pol,
 482         .name = "ondemand",
 483 };
 484
 485 /************************** sysfs end ************************/
 486
 487 static int od_init(struct dbs_data *dbs_data, bool notify)
 488 {
 489         struct od_dbs_tuners *tuners;
 490         u64 idle_time;
 491         int cpu;
 492
 493         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 494         if (!tuners) {
 495                 pr_err("%s: kzalloc failed\n", __func__);
 496                 return -ENOMEM;
 497         }
 498
 499         cpu = get_cpu();
 500         idle_time = get_cpu_idle_time_us(cpu, NULL);
 501         put_cpu();
 502         if (idle_time != -1ULL) {
 503                 /* Idle micro accounting is supported. Use finer thresholds */
 504                 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 505                 /*
 506                  * In nohz/micro accounting case we set the minimum frequency
 507                  * not depending on HZ, but fixed (very low). The deferred
 508                  * timer might skip some samples if idle/sleeping as needed.
 509                 */
 510                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 511         } else {
 512                 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 513
 514                 /* For correct statistics, we need 10 ticks for each measure */
 515                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 516                         jiffies_to_usecs(10);
 517         }
 518
 519         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 520         tuners->ignore_nice_load = 0;
 521         tuners->powersave_bias = default_powersave_bias;
 522         tuners->io_is_busy = should_io_be_busy();
 523
 524         dbs_data->tuners = tuners;
 525         return 0;
 526 }
 527
 528 static void od_exit(struct dbs_data *dbs_data, bool notify)
 529 {
 530         kfree(dbs_data->tuners);
 531 }
 532
 533 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 534
 535 static struct od_ops od_ops = {
 536         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 537         .powersave_bias_target = generic_powersave_bias_target,
 538         .freq_increase = dbs_freq_increase,
 539 };
 540
 541 static struct common_dbs_data od_dbs_cdata = {
 542         .governor = GOV_ONDEMAND,
 543         .attr_group_gov_sys = &od_attr_group_gov_sys,
 544         .attr_group_gov_pol = &od_attr_group_gov_pol,
 545         .get_cpu_cdbs = get_cpu_cdbs,
 546         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 547         .gov_dbs_timer = od_dbs_timer,
 548         .gov_check_cpu = od_check_cpu,
 549         .gov_ops = &od_ops,
 550         .init = od_init,
 551         .exit = od_exit,
 552         .mutex = __MUTEX_INITIALIZER(od_dbs_cdata.mutex),
 553 };
 554
 555 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 556                 unsigned int event)
 557 {
 558         return cpufreq_governor_dbs(policy, &od_dbs_cdata, event);
 559 }
 560
 561 static struct cpufreq_governor cpufreq_gov_ondemand = {
 562         .name                   = "ondemand",
 563         .governor               = od_cpufreq_governor_dbs,
 564         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 565         .owner                  = THIS_MODULE,
 566 };
 567
 568 static void od_set_powersave_bias(unsigned int powersave_bias)
 569 {
 570         struct cpufreq_policy *policy;
 571         struct dbs_data *dbs_data;
 572         struct od_dbs_tuners *od_tuners;
 573         unsigned int cpu;
 574         cpumask_t done;
 575
 576         default_powersave_bias = powersave_bias;
 577         cpumask_clear(&done);
 578
 579         get_online_cpus();
 580         for_each_online_cpu(cpu) {
 581                 struct cpu_common_dbs_info *shared;
 582
 583                 if (cpumask_test_cpu(cpu, &done))
 584                         continue;
 585
 586                 shared = per_cpu(od_cpu_dbs_info, cpu).cdbs.shared;
 587                 if (!shared)
 588                         continue;
 589
 590                 policy = shared->policy;
 591                 cpumask_or(&done, &done, policy->cpus);
 592
 593                 if (policy->governor != &cpufreq_gov_ondemand)
 594                         continue;
 595
 596                 dbs_data = policy->governor_data;
 597                 od_tuners = dbs_data->tuners;
 598                 od_tuners->powersave_bias = default_powersave_bias;
 599         }
 600         put_online_cpus();
 601 }
 602
 603 void od_register_powersave_bias_handler(unsigned int (*f)
 604                 (struct cpufreq_policy *, unsigned int, unsigned int),
 605                 unsigned int powersave_bias)
 606 {
 607         od_ops.powersave_bias_target = f;
 608         od_set_powersave_bias(powersave_bias);
 609 }
 610 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 611
 612 void od_unregister_powersave_bias_handler(void)
 613 {
 614         od_ops.powersave_bias_target = generic_powersave_bias_target;
 615         od_set_powersave_bias(0);
 616 }
 617 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 618
 619 static int __init cpufreq_gov_dbs_init(void)
 620 {
 621         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 622 }
 623
 624 static void __exit cpufreq_gov_dbs_exit(void)
 625 {
 626         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 627 }
 628
 629 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 630 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 631 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 632         "Low Latency Frequency Transition capable processors");
 633 MODULE_LICENSE("GPL");
 634
 635 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 636 struct cpufreq_governor *cpufreq_default_governor(void)
 637 {
 638         return &cpufreq_gov_ondemand;
 639 }
 640
 641 fs_initcall(cpufreq_gov_dbs_init);
 642 #else
 643 module_init(cpufreq_gov_dbs_init);
 644 #endif
 645 module_exit(cpufreq_gov_dbs_exit);