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)
 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         /* Common NORMAL_SAMPLE setup */
 202         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 203         if (sample_type == OD_SUB_SAMPLE) {
 204                 delay = dbs_info->freq_lo_jiffies;
 205                 __cpufreq_driver_target(policy, dbs_info->freq_lo,
 206                                         CPUFREQ_RELATION_H);
 207         } else {
 208                 dbs_check_cpu(dbs_data, cpu);
 209                 if (dbs_info->freq_lo) {
 210                         /* Setup timer for SUB_SAMPLE */
 211                         dbs_info->sample_type = OD_SUB_SAMPLE;
 212                         delay = dbs_info->freq_hi_jiffies;
 213                 }
 214         }
 215
 216         if (!delay)
 217                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 218                                 * dbs_info->rate_mult);
 219
 220         return delay;
 221 }
 222
 223 /************************** sysfs interface ************************/
 224 static struct common_dbs_data od_dbs_cdata;
 225
 226 /**
 227  * update_sampling_rate - update sampling rate effective immediately if needed.
 228  * @new_rate: new sampling rate
 229  *
 230  * If new rate is smaller than the old, simply updating
 231  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 232  * original sampling_rate was 1 second and the requested new sampling rate is 10
 233  * ms because the user needs immediate reaction from ondemand governor, but not
 234  * sure if higher frequency will be required or not, then, the governor may
 235  * change the sampling rate too late; up to 1 second later. Thus, if we are
 236  * reducing the sampling rate, we need to make the new value effective
 237  * immediately.
 238  */
 239 static void update_sampling_rate(struct dbs_data *dbs_data,
 240                 unsigned int new_rate)
 241 {
 242         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 243         struct cpumask cpumask;
 244         int cpu;
 245
 246         od_tuners->sampling_rate = new_rate = max(new_rate,
 247                         dbs_data->min_sampling_rate);
 248
 249         /*
 250          * Lock governor so that governor start/stop can't execute in parallel.
 251          */
 252         mutex_lock(&dbs_data_mutex);
 253
 254         cpumask_copy(&cpumask, cpu_online_mask);
 255
 256         for_each_cpu(cpu, &cpumask) {
 257                 struct cpufreq_policy *policy;
 258                 struct od_cpu_dbs_info_s *dbs_info;
 259                 struct cpu_dbs_info *cdbs;
 260                 struct cpu_common_dbs_info *shared;
 261
 262                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 263                 cdbs = &dbs_info->cdbs;
 264                 shared = cdbs->shared;
 265
 266                 /*
 267                  * A valid shared and shared->policy means governor hasn't
 268                  * stopped or exited yet.
 269                  */
 270                 if (!shared || !shared->policy)
 271                         continue;
 272
 273                 policy = shared->policy;
 274
 275                 /* clear all CPUs of this policy */
 276                 cpumask_andnot(&cpumask, &cpumask, policy->cpus);
 277
 278                 /*
 279                  * Update sampling rate for CPUs whose policy is governed by
 280                  * dbs_data. In case of governor_per_policy, only a single
 281                  * policy will be governed by dbs_data, otherwise there can be
 282                  * multiple policies that are governed by the same dbs_data.
 283                  */
 284                 if (dbs_data == policy->governor_data) {
 285                         mutex_lock(&shared->timer_mutex);
 286                         /*
 287                          * On 32-bit architectures this may race with the
 288                          * sample_delay_ns read in dbs_update_util_handler(),
 289                          * but that really doesn't matter.  If the read returns
 290                          * a value that's too big, the sample will be skipped,
 291                          * but the next invocation of dbs_update_util_handler()
 292                          * (when the update has been completed) will take a
 293                          * sample.  If the returned value is too small, the
 294                          * sample will be taken immediately, but that isn't a
 295                          * problem, as we want the new rate to take effect
 296                          * immediately anyway.
 297                          *
 298                          * If this runs in parallel with dbs_work_handler(), we
 299                          * may end up overwriting the sample_delay_ns value that
 300                          * it has just written, but the difference should not be
 301                          * too big and it will be corrected next time a sample
 302                          * is taken, so it shouldn't be significant.
 303                          */
 304                         gov_update_sample_delay(shared, new_rate);
 305                         mutex_unlock(&shared->timer_mutex);
 306                 }
 307         }
 308
 309         mutex_unlock(&dbs_data_mutex);
 310 }
 311
 312 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 313                 size_t count)
 314 {
 315         unsigned int input;
 316         int ret;
 317         ret = sscanf(buf, "%u", &input);
 318         if (ret != 1)
 319                 return -EINVAL;
 320
 321         update_sampling_rate(dbs_data, input);
 322         return count;
 323 }
 324
 325 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
 326                 size_t count)
 327 {
 328         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 329         unsigned int input;
 330         int ret;
 331         unsigned int j;
 332
 333         ret = sscanf(buf, "%u", &input);
 334         if (ret != 1)
 335                 return -EINVAL;
 336         od_tuners->io_is_busy = !!input;
 337
 338         /* we need to re-evaluate prev_cpu_idle */
 339         for_each_online_cpu(j) {
 340                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 341                                                                         j);
 342                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 343                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 344         }
 345         return count;
 346 }
 347
 348 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 349                 size_t count)
 350 {
 351         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 352         unsigned int input;
 353         int ret;
 354         ret = sscanf(buf, "%u", &input);
 355
 356         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 357                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 358                 return -EINVAL;
 359         }
 360
 361         od_tuners->up_threshold = input;
 362         return count;
 363 }
 364
 365 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 366                 const char *buf, size_t count)
 367 {
 368         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 369         unsigned int input, j;
 370         int ret;
 371         ret = sscanf(buf, "%u", &input);
 372
 373         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 374                 return -EINVAL;
 375         od_tuners->sampling_down_factor = input;
 376
 377         /* Reset down sampling multiplier in case it was active */
 378         for_each_online_cpu(j) {
 379                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 380                                 j);
 381                 dbs_info->rate_mult = 1;
 382         }
 383         return count;
 384 }
 385
 386 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 387                 const char *buf, size_t count)
 388 {
 389         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 390         unsigned int input;
 391         int ret;
 392
 393         unsigned int j;
 394
 395         ret = sscanf(buf, "%u", &input);
 396         if (ret != 1)
 397                 return -EINVAL;
 398
 399         if (input > 1)
 400                 input = 1;
 401
 402         if (input == od_tuners->ignore_nice_load) { /* nothing to do */
 403                 return count;
 404         }
 405         od_tuners->ignore_nice_load = input;
 406
 407         /* we need to re-evaluate prev_cpu_idle */
 408         for_each_online_cpu(j) {
 409                 struct od_cpu_dbs_info_s *dbs_info;
 410                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 411                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 412                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 413                 if (od_tuners->ignore_nice_load)
 414                         dbs_info->cdbs.prev_cpu_nice =
 415                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 416
 417         }
 418         return count;
 419 }
 420
 421 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf,
 422                 size_t count)
 423 {
 424         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 425         unsigned int input;
 426         int ret;
 427         ret = sscanf(buf, "%u", &input);
 428
 429         if (ret != 1)
 430                 return -EINVAL;
 431
 432         if (input > 1000)
 433                 input = 1000;
 434
 435         od_tuners->powersave_bias = input;
 436         ondemand_powersave_bias_init();
 437         return count;
 438 }
 439
 440 show_store_one(od, sampling_rate);
 441 show_store_one(od, io_is_busy);
 442 show_store_one(od, up_threshold);
 443 show_store_one(od, sampling_down_factor);
 444 show_store_one(od, ignore_nice_load);
 445 show_store_one(od, powersave_bias);
 446 declare_show_sampling_rate_min(od);
 447
 448 gov_sys_pol_attr_rw(sampling_rate);
 449 gov_sys_pol_attr_rw(io_is_busy);
 450 gov_sys_pol_attr_rw(up_threshold);
 451 gov_sys_pol_attr_rw(sampling_down_factor);
 452 gov_sys_pol_attr_rw(ignore_nice_load);
 453 gov_sys_pol_attr_rw(powersave_bias);
 454 gov_sys_pol_attr_ro(sampling_rate_min);
 455
 456 static struct attribute *dbs_attributes_gov_sys[] = {
 457         &sampling_rate_min_gov_sys.attr,
 458         &sampling_rate_gov_sys.attr,
 459         &up_threshold_gov_sys.attr,
 460         &sampling_down_factor_gov_sys.attr,
 461         &ignore_nice_load_gov_sys.attr,
 462         &powersave_bias_gov_sys.attr,
 463         &io_is_busy_gov_sys.attr,
 464         NULL
 465 };
 466
 467 static struct attribute_group od_attr_group_gov_sys = {
 468         .attrs = dbs_attributes_gov_sys,
 469         .name = "ondemand",
 470 };
 471
 472 static struct attribute *dbs_attributes_gov_pol[] = {
 473         &sampling_rate_min_gov_pol.attr,
 474         &sampling_rate_gov_pol.attr,
 475         &up_threshold_gov_pol.attr,
 476         &sampling_down_factor_gov_pol.attr,
 477         &ignore_nice_load_gov_pol.attr,
 478         &powersave_bias_gov_pol.attr,
 479         &io_is_busy_gov_pol.attr,
 480         NULL
 481 };
 482
 483 static struct attribute_group od_attr_group_gov_pol = {
 484         .attrs = dbs_attributes_gov_pol,
 485         .name = "ondemand",
 486 };
 487
 488 /************************** sysfs end ************************/
 489
 490 static int od_init(struct dbs_data *dbs_data, bool notify)
 491 {
 492         struct od_dbs_tuners *tuners;
 493         u64 idle_time;
 494         int cpu;
 495
 496         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 497         if (!tuners) {
 498                 pr_err("%s: kzalloc failed\n", __func__);
 499                 return -ENOMEM;
 500         }
 501
 502         cpu = get_cpu();
 503         idle_time = get_cpu_idle_time_us(cpu, NULL);
 504         put_cpu();
 505         if (idle_time != -1ULL) {
 506                 /* Idle micro accounting is supported. Use finer thresholds */
 507                 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 508                 /*
 509                  * In nohz/micro accounting case we set the minimum frequency
 510                  * not depending on HZ, but fixed (very low). The deferred
 511                  * timer might skip some samples if idle/sleeping as needed.
 512                 */
 513                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 514         } else {
 515                 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 516
 517                 /* For correct statistics, we need 10 ticks for each measure */
 518                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 519                         jiffies_to_usecs(10);
 520         }
 521
 522         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 523         tuners->ignore_nice_load = 0;
 524         tuners->powersave_bias = default_powersave_bias;
 525         tuners->io_is_busy = should_io_be_busy();
 526
 527         dbs_data->tuners = tuners;
 528         return 0;
 529 }
 530
 531 static void od_exit(struct dbs_data *dbs_data, bool notify)
 532 {
 533         kfree(dbs_data->tuners);
 534 }
 535
 536 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 537
 538 static struct od_ops od_ops = {
 539         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 540         .powersave_bias_target = generic_powersave_bias_target,
 541         .freq_increase = dbs_freq_increase,
 542 };
 543
 544 static struct common_dbs_data od_dbs_cdata = {
 545         .governor = GOV_ONDEMAND,
 546         .attr_group_gov_sys = &od_attr_group_gov_sys,
 547         .attr_group_gov_pol = &od_attr_group_gov_pol,
 548         .get_cpu_cdbs = get_cpu_cdbs,
 549         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 550         .gov_dbs_timer = od_dbs_timer,
 551         .gov_check_cpu = od_check_cpu,
 552         .gov_ops = &od_ops,
 553         .init = od_init,
 554         .exit = od_exit,
 555 };
 556
 557 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 558                 unsigned int event)
 559 {
 560         return cpufreq_governor_dbs(policy, &od_dbs_cdata, event);
 561 }
 562
 563 static struct cpufreq_governor cpufreq_gov_ondemand = {
 564         .name                   = "ondemand",
 565         .governor               = od_cpufreq_governor_dbs,
 566         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 567         .owner                  = THIS_MODULE,
 568 };
 569
 570 static void od_set_powersave_bias(unsigned int powersave_bias)
 571 {
 572         struct cpufreq_policy *policy;
 573         struct dbs_data *dbs_data;
 574         struct od_dbs_tuners *od_tuners;
 575         unsigned int cpu;
 576         cpumask_t done;
 577
 578         default_powersave_bias = powersave_bias;
 579         cpumask_clear(&done);
 580
 581         get_online_cpus();
 582         for_each_online_cpu(cpu) {
 583                 struct cpu_common_dbs_info *shared;
 584
 585                 if (cpumask_test_cpu(cpu, &done))
 586                         continue;
 587
 588                 shared = per_cpu(od_cpu_dbs_info, cpu).cdbs.shared;
 589                 if (!shared)
 590                         continue;
 591
 592                 policy = shared->policy;
 593                 cpumask_or(&done, &done, policy->cpus);
 594
 595                 if (policy->governor != &cpufreq_gov_ondemand)
 596                         continue;
 597
 598                 dbs_data = policy->governor_data;
 599                 od_tuners = dbs_data->tuners;
 600                 od_tuners->powersave_bias = default_powersave_bias;
 601         }
 602         put_online_cpus();
 603 }
 604
 605 void od_register_powersave_bias_handler(unsigned int (*f)
 606                 (struct cpufreq_policy *, unsigned int, unsigned int),
 607                 unsigned int powersave_bias)
 608 {
 609         od_ops.powersave_bias_target = f;
 610         od_set_powersave_bias(powersave_bias);
 611 }
 612 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 613
 614 void od_unregister_powersave_bias_handler(void)
 615 {
 616         od_ops.powersave_bias_target = generic_powersave_bias_target;
 617         od_set_powersave_bias(0);
 618 }
 619 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 620
 621 static int __init cpufreq_gov_dbs_init(void)
 622 {
 623         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 624 }
 625
 626 static void __exit cpufreq_gov_dbs_exit(void)
 627 {
 628         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 629 }
 630
 631 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 632 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 633 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 634         "Low Latency Frequency Transition capable processors");
 635 MODULE_LICENSE("GPL");
 636
 637 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 638 struct cpufreq_governor *cpufreq_default_governor(void)
 639 {
 640         return &cpufreq_gov_ondemand;
 641 }
 642
 643 fs_initcall(cpufreq_gov_dbs_init);
 644 #else
 645 module_init(cpufreq_gov_dbs_init);
 646 #endif
 647 module_exit(cpufreq_gov_dbs_exit);