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/cpufreq.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/kernel_stat.h>
  19 #include <linux/kobject.h>
  20 #include <linux/module.h>
  21 #include <linux/mutex.h>
  22 #include <linux/percpu-defs.h>
  23 #include <linux/slab.h>
  24 #include <linux/sysfs.h>
  25 #include <linux/tick.h>
  26 #include <linux/types.h>
  27 #include <linux/cpu.h>
  28
  29 #include "cpufreq_governor.h"
  30
  31 /* On-demand governor macros */
  32 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  33 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  34 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
  35 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  36 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  37 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
  38 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  39
  40 static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
  41
  42 static struct od_ops od_ops;
  43
  44 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
  45 static struct cpufreq_governor cpufreq_gov_ondemand;
  46 #endif
  47
  48 static unsigned int default_powersave_bias;
  49
  50 static void ondemand_powersave_bias_init_cpu(int cpu)
  51 {
  52         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
  53
  54         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
  55         dbs_info->freq_lo = 0;
  56 }
  57
  58 /*
  59  * Not all CPUs want IO time to be accounted as busy; this depends on how
  60  * efficient idling at a higher frequency/voltage is.
  61  * Pavel Machek says this is not so for various generations of AMD and old
  62  * Intel systems.
  63  * Mike Chan (android.com) claims this is also not true for ARM.
  64  * Because of this, whitelist specific known (series) of CPUs by default, and
  65  * leave all others up to the user.
  66  */
  67 static int should_io_be_busy(void)
  68 {
  69 #if defined(CONFIG_X86)
  70         /*
  71          * For Intel, Core 2 (model 15) and later have an efficient idle.
  72          */
  73         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  74                         boot_cpu_data.x86 == 6 &&
  75                         boot_cpu_data.x86_model >= 15)
  76                 return 1;
  77 #endif
  78         return 0;
  79 }
  80
  81 /*
  82  * Find right freq to be set now with powersave_bias on.
  83  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
  84  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
  85  */
  86 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
  87                 unsigned int freq_next, unsigned int relation)
  88 {
  89         unsigned int freq_req, freq_reduc, freq_avg;
  90         unsigned int freq_hi, freq_lo;
  91         unsigned int index = 0;
  92         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
  93         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
  94                                                    policy->cpu);
  95         struct dbs_data *dbs_data = policy->governor_data;
  96         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  97
  98         if (!dbs_info->freq_table) {
  99                 dbs_info->freq_lo = 0;
 100                 dbs_info->freq_lo_jiffies = 0;
 101                 return freq_next;
 102         }
 103
 104         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
 105                         relation, &index);
 106         freq_req = dbs_info->freq_table[index].frequency;
 107         freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
 108         freq_avg = freq_req - freq_reduc;
 109
 110         /* Find freq bounds for freq_avg in freq_table */
 111         index = 0;
 112         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 113                         CPUFREQ_RELATION_H, &index);
 114         freq_lo = dbs_info->freq_table[index].frequency;
 115         index = 0;
 116         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 117                         CPUFREQ_RELATION_L, &index);
 118         freq_hi = dbs_info->freq_table[index].frequency;
 119
 120         /* Find out how long we have to be in hi and lo freqs */
 121         if (freq_hi == freq_lo) {
 122                 dbs_info->freq_lo = 0;
 123                 dbs_info->freq_lo_jiffies = 0;
 124                 return freq_lo;
 125         }
 126         jiffies_total = usecs_to_jiffies(od_tuners->sampling_rate);
 127         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 128         jiffies_hi += ((freq_hi - freq_lo) / 2);
 129         jiffies_hi /= (freq_hi - freq_lo);
 130         jiffies_lo = jiffies_total - jiffies_hi;
 131         dbs_info->freq_lo = freq_lo;
 132         dbs_info->freq_lo_jiffies = jiffies_lo;
 133         dbs_info->freq_hi_jiffies = jiffies_hi;
 134         return freq_hi;
 135 }
 136
 137 static void ondemand_powersave_bias_init(void)
 138 {
 139         int i;
 140         for_each_online_cpu(i) {
 141                 ondemand_powersave_bias_init_cpu(i);
 142         }
 143 }
 144
 145 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
 146 {
 147         struct dbs_data *dbs_data = p->governor_data;
 148         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 149
 150         if (od_tuners->powersave_bias)
 151                 freq = od_ops.powersave_bias_target(p, freq,
 152                                 CPUFREQ_RELATION_H);
 153         else if (p->cur == p->max)
 154                 return;
 155
 156         __cpufreq_driver_target(p, freq, od_tuners->powersave_bias ?
 157                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 158 }
 159
 160 /*
 161  * Every sampling_rate, we check, if current idle time is less than 20%
 162  * (default), then we try to increase frequency. Else, we adjust the frequency
 163  * proportional to load.
 164  */
 165 static void od_check_cpu(int cpu, unsigned int load)
 166 {
 167         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 168         struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
 169         struct dbs_data *dbs_data = policy->governor_data;
 170         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 171
 172         dbs_info->freq_lo = 0;
 173
 174         /* Check for frequency increase */
 175         if (load > od_tuners->up_threshold) {
 176                 /* If switching to max speed, apply sampling_down_factor */
 177                 if (policy->cur < policy->max)
 178                         dbs_info->rate_mult =
 179                                 od_tuners->sampling_down_factor;
 180                 dbs_freq_increase(policy, policy->max);
 181                 return;
 182         } else {
 183                 /* Calculate the next frequency proportional to load */
 184                 unsigned int freq_next;
 185                 freq_next = load * policy->cpuinfo.max_freq / 100;
 186
 187                 /* No longer fully busy, reset rate_mult */
 188                 dbs_info->rate_mult = 1;
 189
 190                 if (freq_next < policy->min)
 191                         freq_next = policy->min;
 192
 193                 if (!od_tuners->powersave_bias) {
 194                         __cpufreq_driver_target(policy, freq_next,
 195                                         CPUFREQ_RELATION_L);
 196                         return;
 197                 }
 198
 199                 freq_next = od_ops.powersave_bias_target(policy, freq_next,
 200                                         CPUFREQ_RELATION_L);
 201                 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
 202         }
 203 }
 204
 205 static void od_dbs_timer(struct work_struct *work)
 206 {
 207         struct od_cpu_dbs_info_s *dbs_info =
 208                 container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
 209         unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 210         struct od_cpu_dbs_info_s *core_dbs_info = &per_cpu(od_cpu_dbs_info,
 211                         cpu);
 212         struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data;
 213         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 214         int delay = 0, sample_type = core_dbs_info->sample_type;
 215         bool modify_all = true;
 216
 217         mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 218         if (!need_load_eval(&core_dbs_info->cdbs, od_tuners->sampling_rate)) {
 219                 modify_all = false;
 220                 goto max_delay;
 221         }
 222
 223         /* Common NORMAL_SAMPLE setup */
 224         core_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 225         if (sample_type == OD_SUB_SAMPLE) {
 226                 delay = core_dbs_info->freq_lo_jiffies;
 227                 __cpufreq_driver_target(core_dbs_info->cdbs.cur_policy,
 228                                 core_dbs_info->freq_lo, CPUFREQ_RELATION_H);
 229         } else {
 230                 dbs_check_cpu(dbs_data, cpu);
 231                 if (core_dbs_info->freq_lo) {
 232                         /* Setup timer for SUB_SAMPLE */
 233                         core_dbs_info->sample_type = OD_SUB_SAMPLE;
 234                         delay = core_dbs_info->freq_hi_jiffies;
 235                 }
 236         }
 237
 238 max_delay:
 239         if (!delay)
 240                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 241                                 * core_dbs_info->rate_mult);
 242
 243         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all);
 244         mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 245 }
 246
 247 /************************** sysfs interface ************************/
 248 static struct common_dbs_data od_dbs_cdata;
 249
 250 /**
 251  * update_sampling_rate - update sampling rate effective immediately if needed.
 252  * @new_rate: new sampling rate
 253  *
 254  * If new rate is smaller than the old, simply updating
 255  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 256  * original sampling_rate was 1 second and the requested new sampling rate is 10
 257  * ms because the user needs immediate reaction from ondemand governor, but not
 258  * sure if higher frequency will be required or not, then, the governor may
 259  * change the sampling rate too late; up to 1 second later. Thus, if we are
 260  * reducing the sampling rate, we need to make the new value effective
 261  * immediately.
 262  */
 263 static void update_sampling_rate(struct dbs_data *dbs_data,
 264                 unsigned int new_rate)
 265 {
 266         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 267         int cpu;
 268
 269         od_tuners->sampling_rate = new_rate = max(new_rate,
 270                         dbs_data->min_sampling_rate);
 271
 272         for_each_online_cpu(cpu) {
 273                 struct cpufreq_policy *policy;
 274                 struct od_cpu_dbs_info_s *dbs_info;
 275                 unsigned long next_sampling, appointed_at;
 276
 277                 policy = cpufreq_cpu_get(cpu);
 278                 if (!policy)
 279                         continue;
 280                 if (policy->governor != &cpufreq_gov_ondemand) {
 281                         cpufreq_cpu_put(policy);
 282                         continue;
 283                 }
 284                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 285                 cpufreq_cpu_put(policy);
 286
 287                 mutex_lock(&dbs_info->cdbs.timer_mutex);
 288
 289                 if (!delayed_work_pending(&dbs_info->cdbs.work)) {
 290                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 291                         continue;
 292                 }
 293
 294                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 295                 appointed_at = dbs_info->cdbs.work.timer.expires;
 296
 297                 if (time_before(next_sampling, appointed_at)) {
 298
 299                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 300                         cancel_delayed_work_sync(&dbs_info->cdbs.work);
 301                         mutex_lock(&dbs_info->cdbs.timer_mutex);
 302
 303                         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy,
 304                                         usecs_to_jiffies(new_rate), true);
 305
 306                 }
 307                 mutex_unlock(&dbs_info->cdbs.timer_mutex);
 308         }
 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)
 490 {
 491         struct od_dbs_tuners *tuners;
 492         u64 idle_time;
 493         int cpu;
 494
 495         tuners = kzalloc(sizeof(struct od_dbs_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         mutex_init(&dbs_data->mutex);
 528         return 0;
 529 }
 530
 531 static void od_exit(struct dbs_data *dbs_data)
 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 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                 if (cpumask_test_cpu(cpu, &done))
 571                         continue;
 572
 573                 policy = per_cpu(od_cpu_dbs_info, cpu).cdbs.cur_policy;
 574                 if (!policy)
 575                         continue;
 576
 577                 cpumask_or(&done, &done, policy->cpus);
 578
 579                 if (policy->governor != &cpufreq_gov_ondemand)
 580                         continue;
 581
 582                 dbs_data = policy->governor_data;
 583                 od_tuners = dbs_data->tuners;
 584                 od_tuners->powersave_bias = default_powersave_bias;
 585         }
 586         put_online_cpus();
 587 }
 588
 589 void od_register_powersave_bias_handler(unsigned int (*f)
 590                 (struct cpufreq_policy *, unsigned int, unsigned int),
 591                 unsigned int powersave_bias)
 592 {
 593         od_ops.powersave_bias_target = f;
 594         od_set_powersave_bias(powersave_bias);
 595 }
 596 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 597
 598 void od_unregister_powersave_bias_handler(void)
 599 {
 600         od_ops.powersave_bias_target = generic_powersave_bias_target;
 601         od_set_powersave_bias(0);
 602 }
 603 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 604
 605 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 606                 unsigned int event)
 607 {
 608         return cpufreq_governor_dbs(policy, &od_dbs_cdata, event);
 609 }
 610
 611 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 612 static
 613 #endif
 614 struct cpufreq_governor cpufreq_gov_ondemand = {
 615         .name                   = "ondemand",
 616         .governor               = od_cpufreq_governor_dbs,
 617         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 618         .owner                  = THIS_MODULE,
 619 };
 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 fs_initcall(cpufreq_gov_dbs_init);
 639 #else
 640 module_init(cpufreq_gov_dbs_init);
 641 #endif
 642 module_exit(cpufreq_gov_dbs_exit);