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