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 cpufreq_policy *policy, bool modify_all)
 195 {
 196         struct dbs_data *dbs_data = policy->governor_data;
 197         unsigned int cpu = policy->cpu;
 198         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 199                         cpu);
 200         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 201         int delay = 0, sample_type = dbs_info->sample_type;
 202
 203         if (!modify_all)
 204                 goto max_delay;
 205
 206         /* Common NORMAL_SAMPLE setup */
 207         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 208         if (sample_type == OD_SUB_SAMPLE) {
 209                 delay = dbs_info->freq_lo_jiffies;
 210                 __cpufreq_driver_target(policy, dbs_info->freq_lo,
 211                                         CPUFREQ_RELATION_H);
 212         } else {
 213                 dbs_check_cpu(dbs_data, cpu);
 214                 if (dbs_info->freq_lo) {
 215                         /* Setup timer for SUB_SAMPLE */
 216                         dbs_info->sample_type = OD_SUB_SAMPLE;
 217                         delay = dbs_info->freq_hi_jiffies;
 218                 }
 219         }
 220
 221 max_delay:
 222         if (!delay)
 223                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 224                                 * dbs_info->rate_mult);
 225
 226         return delay;
 227 }
 228
 229 /************************** sysfs interface ************************/
 230 static struct common_dbs_data od_dbs_cdata;
 231
 232 /**
 233  * update_sampling_rate - update sampling rate effective immediately if needed.
 234  * @new_rate: new sampling rate
 235  *
 236  * If new rate is smaller than the old, simply updating
 237  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 238  * original sampling_rate was 1 second and the requested new sampling rate is 10
 239  * ms because the user needs immediate reaction from ondemand governor, but not
 240  * sure if higher frequency will be required or not, then, the governor may
 241  * change the sampling rate too late; up to 1 second later. Thus, if we are
 242  * reducing the sampling rate, we need to make the new value effective
 243  * immediately.
 244  */
 245 static void update_sampling_rate(struct dbs_data *dbs_data,
 246                 unsigned int new_rate)
 247 {
 248         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 249         struct cpumask cpumask;
 250         int cpu;
 251
 252         od_tuners->sampling_rate = new_rate = max(new_rate,
 253                         dbs_data->min_sampling_rate);
 254
 255         /*
 256          * Lock governor so that governor start/stop can't execute in parallel.
 257          */
 258         mutex_lock(&od_dbs_cdata.mutex);
 259
 260         cpumask_copy(&cpumask, cpu_online_mask);
 261
 262         for_each_cpu(cpu, &cpumask) {
 263                 struct cpufreq_policy *policy;
 264                 struct od_cpu_dbs_info_s *dbs_info;
 265                 struct cpu_dbs_info *cdbs;
 266                 struct cpu_common_dbs_info *shared;
 267                 unsigned long next_sampling, appointed_at;
 268
 269                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 270                 cdbs = &dbs_info->cdbs;
 271                 shared = cdbs->shared;
 272
 273                 /*
 274                  * A valid shared and shared->policy means governor hasn't
 275                  * stopped or exited yet.
 276                  */
 277                 if (!shared || !shared->policy)
 278                         continue;
 279
 280                 policy = shared->policy;
 281
 282                 /* clear all CPUs of this policy */
 283                 cpumask_andnot(&cpumask, &cpumask, policy->cpus);
 284
 285                 /*
 286                  * Update sampling rate for CPUs whose policy is governed by
 287                  * dbs_data. In case of governor_per_policy, only a single
 288                  * policy will be governed by dbs_data, otherwise there can be
 289                  * multiple policies that are governed by the same dbs_data.
 290                  */
 291                 if (dbs_data != policy->governor_data)
 292                         continue;
 293
 294                 /*
 295                  * Checking this for any CPU should be fine, timers for all of
 296                  * them are scheduled together.
 297                  */
 298                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 299                 appointed_at = dbs_info->cdbs.timer.expires;
 300
 301                 if (time_before(next_sampling, appointed_at)) {
 302                         gov_cancel_work(shared);
 303                         gov_add_timers(policy, usecs_to_jiffies(new_rate));
 304
 305                 }
 306         }
 307
 308         mutex_unlock(&od_dbs_cdata.mutex);
 309 }
 310
 311 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 312                 size_t count)
 313 {
 314         unsigned int input;
 315         int ret;
 316         ret = sscanf(buf, "%u", &input);
 317         if (ret != 1)
 318                 return -EINVAL;
 319
 320         update_sampling_rate(dbs_data, input);
 321         return count;
 322 }
 323
 324 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
 325                 size_t count)
 326 {
 327         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 328         unsigned int input;
 329         int ret;
 330         unsigned int j;
 331
 332         ret = sscanf(buf, "%u", &input);
 333         if (ret != 1)
 334                 return -EINVAL;
 335         od_tuners->io_is_busy = !!input;
 336
 337         /* we need to re-evaluate prev_cpu_idle */
 338         for_each_online_cpu(j) {
 339                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 340                                                                         j);
 341                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 342                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 343         }
 344         return count;
 345 }
 346
 347 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 348                 size_t count)
 349 {
 350         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 351         unsigned int input;
 352         int ret;
 353         ret = sscanf(buf, "%u", &input);
 354
 355         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 356                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 357                 return -EINVAL;
 358         }
 359
 360         od_tuners->up_threshold = input;
 361         return count;
 362 }
 363
 364 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 365                 const char *buf, size_t count)
 366 {
 367         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 368         unsigned int input, j;
 369         int ret;
 370         ret = sscanf(buf, "%u", &input);
 371
 372         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 373                 return -EINVAL;
 374         od_tuners->sampling_down_factor = input;
 375
 376         /* Reset down sampling multiplier in case it was active */
 377         for_each_online_cpu(j) {
 378                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 379                                 j);
 380                 dbs_info->rate_mult = 1;
 381         }
 382         return count;
 383 }
 384
 385 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 386                 const char *buf, size_t count)
 387 {
 388         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 389         unsigned int input;
 390         int ret;
 391
 392         unsigned int j;
 393
 394         ret = sscanf(buf, "%u", &input);
 395         if (ret != 1)
 396                 return -EINVAL;
 397
 398         if (input > 1)
 399                 input = 1;
 400
 401         if (input == od_tuners->ignore_nice_load) { /* nothing to do */
 402                 return count;
 403         }
 404         od_tuners->ignore_nice_load = input;
 405
 406         /* we need to re-evaluate prev_cpu_idle */
 407         for_each_online_cpu(j) {
 408                 struct od_cpu_dbs_info_s *dbs_info;
 409                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 410                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 411                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 412                 if (od_tuners->ignore_nice_load)
 413                         dbs_info->cdbs.prev_cpu_nice =
 414                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 415
 416         }
 417         return count;
 418 }
 419
 420 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf,
 421                 size_t count)
 422 {
 423         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 424         unsigned int input;
 425         int ret;
 426         ret = sscanf(buf, "%u", &input);
 427
 428         if (ret != 1)
 429                 return -EINVAL;
 430
 431         if (input > 1000)
 432                 input = 1000;
 433
 434         od_tuners->powersave_bias = input;
 435         ondemand_powersave_bias_init();
 436         return count;
 437 }
 438
 439 show_store_one(od, sampling_rate);
 440 show_store_one(od, io_is_busy);
 441 show_store_one(od, up_threshold);
 442 show_store_one(od, sampling_down_factor);
 443 show_store_one(od, ignore_nice_load);
 444 show_store_one(od, powersave_bias);
 445 declare_show_sampling_rate_min(od);
 446
 447 gov_sys_pol_attr_rw(sampling_rate);
 448 gov_sys_pol_attr_rw(io_is_busy);
 449 gov_sys_pol_attr_rw(up_threshold);
 450 gov_sys_pol_attr_rw(sampling_down_factor);
 451 gov_sys_pol_attr_rw(ignore_nice_load);
 452 gov_sys_pol_attr_rw(powersave_bias);
 453 gov_sys_pol_attr_ro(sampling_rate_min);
 454
 455 static struct attribute *dbs_attributes_gov_sys[] = {
 456         &sampling_rate_min_gov_sys.attr,
 457         &sampling_rate_gov_sys.attr,
 458         &up_threshold_gov_sys.attr,
 459         &sampling_down_factor_gov_sys.attr,
 460         &ignore_nice_load_gov_sys.attr,
 461         &powersave_bias_gov_sys.attr,
 462         &io_is_busy_gov_sys.attr,
 463         NULL
 464 };
 465
 466 static struct attribute_group od_attr_group_gov_sys = {
 467         .attrs = dbs_attributes_gov_sys,
 468         .name = "ondemand",
 469 };
 470
 471 static struct attribute *dbs_attributes_gov_pol[] = {
 472         &sampling_rate_min_gov_pol.attr,
 473         &sampling_rate_gov_pol.attr,
 474         &up_threshold_gov_pol.attr,
 475         &sampling_down_factor_gov_pol.attr,
 476         &ignore_nice_load_gov_pol.attr,
 477         &powersave_bias_gov_pol.attr,
 478         &io_is_busy_gov_pol.attr,
 479         NULL
 480 };
 481
 482 static struct attribute_group od_attr_group_gov_pol = {
 483         .attrs = dbs_attributes_gov_pol,
 484         .name = "ondemand",
 485 };
 486
 487 /************************** sysfs end ************************/
 488
 489 static int od_init(struct dbs_data *dbs_data, bool notify)
 490 {
 491         struct od_dbs_tuners *tuners;
 492         u64 idle_time;
 493         int cpu;
 494
 495         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 496         if (!tuners) {
 497                 pr_err("%s: kzalloc failed\n", __func__);
 498                 return -ENOMEM;
 499         }
 500
 501         cpu = get_cpu();
 502         idle_time = get_cpu_idle_time_us(cpu, NULL);
 503         put_cpu();
 504         if (idle_time != -1ULL) {
 505                 /* Idle micro accounting is supported. Use finer thresholds */
 506                 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 507                 /*
 508                  * In nohz/micro accounting case we set the minimum frequency
 509                  * not depending on HZ, but fixed (very low). The deferred
 510                  * timer might skip some samples if idle/sleeping as needed.
 511                 */
 512                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 513         } else {
 514                 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 515
 516                 /* For correct statistics, we need 10 ticks for each measure */
 517                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 518                         jiffies_to_usecs(10);
 519         }
 520
 521         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 522         tuners->ignore_nice_load = 0;
 523         tuners->powersave_bias = default_powersave_bias;
 524         tuners->io_is_busy = should_io_be_busy();
 525
 526         dbs_data->tuners = tuners;
 527         return 0;
 528 }
 529
 530 static void od_exit(struct dbs_data *dbs_data, bool notify)
 531 {
 532         kfree(dbs_data->tuners);
 533 }
 534
 535 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 536
 537 static struct od_ops od_ops = {
 538         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 539         .powersave_bias_target = generic_powersave_bias_target,
 540         .freq_increase = dbs_freq_increase,
 541 };
 542
 543 static struct common_dbs_data od_dbs_cdata = {
 544         .governor = GOV_ONDEMAND,
 545         .attr_group_gov_sys = &od_attr_group_gov_sys,
 546         .attr_group_gov_pol = &od_attr_group_gov_pol,
 547         .get_cpu_cdbs = get_cpu_cdbs,
 548         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 549         .gov_dbs_timer = od_dbs_timer,
 550         .gov_check_cpu = od_check_cpu,
 551         .gov_ops = &od_ops,
 552         .init = od_init,
 553         .exit = od_exit,
 554         .mutex = __MUTEX_INITIALIZER(od_dbs_cdata.mutex),
 555 };
 556
 557 static void od_set_powersave_bias(unsigned int powersave_bias)
 558 {
 559         struct cpufreq_policy *policy;
 560         struct dbs_data *dbs_data;
 561         struct od_dbs_tuners *od_tuners;
 562         unsigned int cpu;
 563         cpumask_t done;
 564
 565         default_powersave_bias = powersave_bias;
 566         cpumask_clear(&done);
 567
 568         get_online_cpus();
 569         for_each_online_cpu(cpu) {
 570                 struct cpu_common_dbs_info *shared;
 571
 572                 if (cpumask_test_cpu(cpu, &done))
 573                         continue;
 574
 575                 shared = per_cpu(od_cpu_dbs_info, cpu).cdbs.shared;
 576                 if (!shared)
 577                         continue;
 578
 579                 policy = shared->policy;
 580                 cpumask_or(&done, &done, policy->cpus);
 581
 582                 if (policy->governor != &cpufreq_gov_ondemand)
 583                         continue;
 584
 585                 dbs_data = policy->governor_data;
 586                 od_tuners = dbs_data->tuners;
 587                 od_tuners->powersave_bias = default_powersave_bias;
 588         }
 589         put_online_cpus();
 590 }
 591
 592 void od_register_powersave_bias_handler(unsigned int (*f)
 593                 (struct cpufreq_policy *, unsigned int, unsigned int),
 594                 unsigned int powersave_bias)
 595 {
 596         od_ops.powersave_bias_target = f;
 597         od_set_powersave_bias(powersave_bias);
 598 }
 599 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 600
 601 void od_unregister_powersave_bias_handler(void)
 602 {
 603         od_ops.powersave_bias_target = generic_powersave_bias_target;
 604         od_set_powersave_bias(0);
 605 }
 606 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 607
 608 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 609                 unsigned int event)
 610 {
 611         return cpufreq_governor_dbs(policy, &od_dbs_cdata, event);
 612 }
 613
 614 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 615 static
 616 #endif
 617 struct cpufreq_governor cpufreq_gov_ondemand = {
 618         .name                   = "ondemand",
 619         .governor               = od_cpufreq_governor_dbs,
 620         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 621         .owner                  = THIS_MODULE,
 622 };
 623
 624 static int __init cpufreq_gov_dbs_init(void)
 625 {
 626         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 627 }
 628
 629 static void __exit cpufreq_gov_dbs_exit(void)
 630 {
 631         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 632 }
 633
 634 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 635 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 636 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 637         "Low Latency Frequency Transition capable processors");
 638 MODULE_LICENSE("GPL");
 639
 640 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 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);