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