drivers/cpufreq/cpufreq_ondemand.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_ondemand.c
   3  *
   4  *  Copyright (C)  2001 Russell King
   5  *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   6  *                      Jun Nakajima <jun.nakajima@intel.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/cpu.h>
  16 #include <linux/percpu-defs.h>
  17 #include <linux/slab.h>
  18 #include <linux/tick.h>
  19 #include "cpufreq_governor.h"
  20
  21 /* On-demand governor macros */
  22 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  23 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  24 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
  25 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  26 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  27 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
  28 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  29
  30 static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
  31
  32 static struct od_ops od_ops;
  33
  34 static unsigned int default_powersave_bias;
  35
  36 static void ondemand_powersave_bias_init_cpu(int cpu)
  37 {
  38         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
  39
  40         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
  41         dbs_info->freq_lo = 0;
  42 }
  43
  44 /*
  45  * Not all CPUs want IO time to be accounted as busy; this depends on how
  46  * efficient idling at a higher frequency/voltage is.
  47  * Pavel Machek says this is not so for various generations of AMD and old
  48  * Intel systems.
  49  * Mike Chan (android.com) claims this is also not true for ARM.
  50  * Because of this, whitelist specific known (series) of CPUs by default, and
  51  * leave all others up to the user.
  52  */
  53 static int should_io_be_busy(void)
  54 {
  55 #if defined(CONFIG_X86)
  56         /*
  57          * For Intel, Core 2 (model 15) and later have an efficient idle.
  58          */
  59         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  60                         boot_cpu_data.x86 == 6 &&
  61                         boot_cpu_data.x86_model >= 15)
  62                 return 1;
  63 #endif
  64         return 0;
  65 }
  66
  67 /*
  68  * Find right freq to be set now with powersave_bias on.
  69  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
  70  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
  71  */
  72 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
  73                 unsigned int freq_next, unsigned int relation)
  74 {
  75         unsigned int freq_req, freq_reduc, freq_avg;
  76         unsigned int freq_hi, freq_lo;
  77         unsigned int index = 0;
  78         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
  79         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
  80                                                    policy->cpu);
  81         struct dbs_data *dbs_data = policy->governor_data;
  82         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  83
  84         if (!dbs_info->freq_table) {
  85                 dbs_info->freq_lo = 0;
  86                 dbs_info->freq_lo_jiffies = 0;
  87                 return freq_next;
  88         }
  89
  90         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
  91                         relation, &index);
  92         freq_req = dbs_info->freq_table[index].frequency;
  93         freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
  94         freq_avg = freq_req - freq_reduc;
  95
  96         /* Find freq bounds for freq_avg in freq_table */
  97         index = 0;
  98         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
  99                         CPUFREQ_RELATION_H, &index);
 100         freq_lo = dbs_info->freq_table[index].frequency;
 101         index = 0;
 102         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 103                         CPUFREQ_RELATION_L, &index);
 104         freq_hi = dbs_info->freq_table[index].frequency;
 105
 106         /* Find out how long we have to be in hi and lo freqs */
 107         if (freq_hi == freq_lo) {
 108                 dbs_info->freq_lo = 0;
 109                 dbs_info->freq_lo_jiffies = 0;
 110                 return freq_lo;
 111         }
 112         jiffies_total = usecs_to_jiffies(od_tuners->sampling_rate);
 113         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 114         jiffies_hi += ((freq_hi - freq_lo) / 2);
 115         jiffies_hi /= (freq_hi - freq_lo);
 116         jiffies_lo = jiffies_total - jiffies_hi;
 117         dbs_info->freq_lo = freq_lo;
 118         dbs_info->freq_lo_jiffies = jiffies_lo;
 119         dbs_info->freq_hi_jiffies = jiffies_hi;
 120         return freq_hi;
 121 }
 122
 123 static void ondemand_powersave_bias_init(void)
 124 {
 125         int i;
 126         for_each_online_cpu(i) {
 127                 ondemand_powersave_bias_init_cpu(i);
 128         }
 129 }
 130
 131 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
 132 {
 133         struct dbs_data *dbs_data = policy->governor_data;
 134         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 135
 136         if (od_tuners->powersave_bias)
 137                 freq = od_ops.powersave_bias_target(policy, freq,
 138                                 CPUFREQ_RELATION_H);
 139         else if (policy->cur == policy->max)
 140                 return;
 141
 142         __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
 143                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 144 }
 145
 146 /*
 147  * Every sampling_rate, we check, if current idle time is less than 20%
 148  * (default), then we try to increase frequency. Else, we adjust the frequency
 149  * proportional to load.
 150  */
 151 static void od_check_cpu(int cpu, unsigned int load)
 152 {
 153         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 154         struct cpufreq_policy *policy = dbs_info->cdbs.shared->policy;
 155         struct dbs_data *dbs_data = policy->governor_data;
 156         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 157
 158         dbs_info->freq_lo = 0;
 159
 160         /* Check for frequency increase */
 161         if (load > od_tuners->up_threshold) {
 162                 /* If switching to max speed, apply sampling_down_factor */
 163                 if (policy->cur < policy->max)
 164                         dbs_info->rate_mult =
 165                                 od_tuners->sampling_down_factor;
 166                 dbs_freq_increase(policy, policy->max);
 167         } else {
 168                 /* Calculate the next frequency proportional to load */
 169                 unsigned int freq_next, min_f, max_f;
 170
 171                 min_f = policy->cpuinfo.min_freq;
 172                 max_f = policy->cpuinfo.max_freq;
 173                 freq_next = min_f + load * (max_f - min_f) / 100;
 174
 175                 /* No longer fully busy, reset rate_mult */
 176                 dbs_info->rate_mult = 1;
 177
 178                 if (!od_tuners->powersave_bias) {
 179                         __cpufreq_driver_target(policy, freq_next,
 180                                         CPUFREQ_RELATION_C);
 181                         return;
 182                 }
 183
 184                 freq_next = od_ops.powersave_bias_target(policy, freq_next,
 185                                         CPUFREQ_RELATION_L);
 186                 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
 187         }
 188 }
 189
 190 static unsigned int od_dbs_timer(struct cpufreq_policy *policy)
 191 {
 192         struct dbs_data *dbs_data = policy->governor_data;
 193         unsigned int cpu = policy->cpu;
 194         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 195                         cpu);
 196         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 197         int delay = 0, sample_type = dbs_info->sample_type;
 198
 199         /* Common NORMAL_SAMPLE setup */
 200         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 201         if (sample_type == OD_SUB_SAMPLE) {
 202                 delay = dbs_info->freq_lo_jiffies;
 203                 __cpufreq_driver_target(policy, dbs_info->freq_lo,
 204                                         CPUFREQ_RELATION_H);
 205         } else {
 206                 dbs_check_cpu(dbs_data, cpu);
 207                 if (dbs_info->freq_lo) {
 208                         /* Setup timer for SUB_SAMPLE */
 209                         dbs_info->sample_type = OD_SUB_SAMPLE;
 210                         delay = dbs_info->freq_hi_jiffies;
 211                 }
 212         }
 213
 214         if (!delay)
 215                 delay = delay_for_sampling_rate(od_tuners->sampling_rate
 216                                 * dbs_info->rate_mult);
 217
 218         return delay;
 219 }
 220
 221 /************************** sysfs interface ************************/
 222 static struct dbs_governor od_dbs_gov;
 223
 224 /**
 225  * update_sampling_rate - update sampling rate effective immediately if needed.
 226  * @new_rate: new sampling rate
 227  *
 228  * If new rate is smaller than the old, simply updating
 229  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 230  * original sampling_rate was 1 second and the requested new sampling rate is 10
 231  * ms because the user needs immediate reaction from ondemand governor, but not
 232  * sure if higher frequency will be required or not, then, the governor may
 233  * change the sampling rate too late; up to 1 second later. Thus, if we are
 234  * reducing the sampling rate, we need to make the new value effective
 235  * immediately.
 236  */
 237 static void update_sampling_rate(struct dbs_data *dbs_data,
 238                 unsigned int new_rate)
 239 {
 240         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 241         struct cpumask cpumask;
 242         int cpu;
 243
 244         od_tuners->sampling_rate = new_rate = max(new_rate,
 245                         dbs_data->min_sampling_rate);
 246
 247         /*
 248          * Lock governor so that governor start/stop can't execute in parallel.
 249          */
 250         mutex_lock(&dbs_data_mutex);
 251
 252         cpumask_copy(&cpumask, cpu_online_mask);
 253
 254         for_each_cpu(cpu, &cpumask) {
 255                 struct cpufreq_policy *policy;
 256                 struct od_cpu_dbs_info_s *dbs_info;
 257                 struct cpu_dbs_info *cdbs;
 258                 struct cpu_common_dbs_info *shared;
 259
 260                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 261                 cdbs = &dbs_info->cdbs;
 262                 shared = cdbs->shared;
 263
 264                 /*
 265                  * A valid shared and shared->policy means governor hasn't
 266                  * stopped or exited yet.
 267                  */
 268                 if (!shared || !shared->policy)
 269                         continue;
 270
 271                 policy = shared->policy;
 272
 273                 /* clear all CPUs of this policy */
 274                 cpumask_andnot(&cpumask, &cpumask, policy->cpus);
 275
 276                 /*
 277                  * Update sampling rate for CPUs whose policy is governed by
 278                  * dbs_data. In case of governor_per_policy, only a single
 279                  * policy will be governed by dbs_data, otherwise there can be
 280                  * multiple policies that are governed by the same dbs_data.
 281                  */
 282                 if (dbs_data == policy->governor_data) {
 283                         mutex_lock(&shared->timer_mutex);
 284                         /*
 285                          * On 32-bit architectures this may race with the
 286                          * sample_delay_ns read in dbs_update_util_handler(),
 287                          * but that really doesn't matter.  If the read returns
 288                          * a value that's too big, the sample will be skipped,
 289                          * but the next invocation of dbs_update_util_handler()
 290                          * (when the update has been completed) will take a
 291                          * sample.  If the returned value is too small, the
 292                          * sample will be taken immediately, but that isn't a
 293                          * problem, as we want the new rate to take effect
 294                          * immediately anyway.
 295                          *
 296                          * If this runs in parallel with dbs_work_handler(), we
 297                          * may end up overwriting the sample_delay_ns value that
 298                          * it has just written, but the difference should not be
 299                          * too big and it will be corrected next time a sample
 300                          * is taken, so it shouldn't be significant.
 301                          */
 302                         gov_update_sample_delay(shared, new_rate);
 303                         mutex_unlock(&shared->timer_mutex);
 304                 }
 305         }
 306
 307         mutex_unlock(&dbs_data_mutex);
 308 }
 309
 310 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 311                 size_t count)
 312 {
 313         unsigned int input;
 314         int ret;
 315         ret = sscanf(buf, "%u", &input);
 316         if (ret != 1)
 317                 return -EINVAL;
 318
 319         update_sampling_rate(dbs_data, input);
 320         return count;
 321 }
 322
 323 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
 324                 size_t count)
 325 {
 326         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 327         unsigned int input;
 328         int ret;
 329         unsigned int j;
 330
 331         ret = sscanf(buf, "%u", &input);
 332         if (ret != 1)
 333                 return -EINVAL;
 334         od_tuners->io_is_busy = !!input;
 335
 336         /* we need to re-evaluate prev_cpu_idle */
 337         for_each_online_cpu(j) {
 338                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 339                                                                         j);
 340                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 341                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 342         }
 343         return count;
 344 }
 345
 346 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 347                 size_t count)
 348 {
 349         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 350         unsigned int input;
 351         int ret;
 352         ret = sscanf(buf, "%u", &input);
 353
 354         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 355                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 356                 return -EINVAL;
 357         }
 358
 359         od_tuners->up_threshold = input;
 360         return count;
 361 }
 362
 363 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 364                 const char *buf, size_t count)
 365 {
 366         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 367         unsigned int input, j;
 368         int ret;
 369         ret = sscanf(buf, "%u", &input);
 370
 371         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 372                 return -EINVAL;
 373         od_tuners->sampling_down_factor = input;
 374
 375         /* Reset down sampling multiplier in case it was active */
 376         for_each_online_cpu(j) {
 377                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 378                                 j);
 379                 dbs_info->rate_mult = 1;
 380         }
 381         return count;
 382 }
 383
 384 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 385                 const char *buf, size_t count)
 386 {
 387         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 388         unsigned int input;
 389         int ret;
 390
 391         unsigned int j;
 392
 393         ret = sscanf(buf, "%u", &input);
 394         if (ret != 1)
 395                 return -EINVAL;
 396
 397         if (input > 1)
 398                 input = 1;
 399
 400         if (input == od_tuners->ignore_nice_load) { /* nothing to do */
 401                 return count;
 402         }
 403         od_tuners->ignore_nice_load = input;
 404
 405         /* we need to re-evaluate prev_cpu_idle */
 406         for_each_online_cpu(j) {
 407                 struct od_cpu_dbs_info_s *dbs_info;
 408                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 409                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 410                         &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
 411                 if (od_tuners->ignore_nice_load)
 412                         dbs_info->cdbs.prev_cpu_nice =
 413                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 414
 415         }
 416         return count;
 417 }
 418
 419 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf,
 420                 size_t count)
 421 {
 422         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 423         unsigned int input;
 424         int ret;
 425         ret = sscanf(buf, "%u", &input);
 426
 427         if (ret != 1)
 428                 return -EINVAL;
 429
 430         if (input > 1000)
 431                 input = 1000;
 432
 433         od_tuners->powersave_bias = input;
 434         ondemand_powersave_bias_init();
 435         return count;
 436 }
 437
 438 show_store_one(od, sampling_rate);
 439 show_store_one(od, io_is_busy);
 440 show_store_one(od, up_threshold);
 441 show_store_one(od, sampling_down_factor);
 442 show_store_one(od, ignore_nice_load);
 443 show_store_one(od, powersave_bias);
 444 declare_show_sampling_rate_min(od);
 445
 446 gov_sys_pol_attr_rw(sampling_rate);
 447 gov_sys_pol_attr_rw(io_is_busy);
 448 gov_sys_pol_attr_rw(up_threshold);
 449 gov_sys_pol_attr_rw(sampling_down_factor);
 450 gov_sys_pol_attr_rw(ignore_nice_load);
 451 gov_sys_pol_attr_rw(powersave_bias);
 452 gov_sys_pol_attr_ro(sampling_rate_min);
 453
 454 static struct attribute *dbs_attributes_gov_sys[] = {
 455         &sampling_rate_min_gov_sys.attr,
 456         &sampling_rate_gov_sys.attr,
 457         &up_threshold_gov_sys.attr,
 458         &sampling_down_factor_gov_sys.attr,
 459         &ignore_nice_load_gov_sys.attr,
 460         &powersave_bias_gov_sys.attr,
 461         &io_is_busy_gov_sys.attr,
 462         NULL
 463 };
 464
 465 static struct attribute_group od_attr_group_gov_sys = {
 466         .attrs = dbs_attributes_gov_sys,
 467         .name = "ondemand",
 468 };
 469
 470 static struct attribute *dbs_attributes_gov_pol[] = {
 471         &sampling_rate_min_gov_pol.attr,
 472         &sampling_rate_gov_pol.attr,
 473         &up_threshold_gov_pol.attr,
 474         &sampling_down_factor_gov_pol.attr,
 475         &ignore_nice_load_gov_pol.attr,
 476         &powersave_bias_gov_pol.attr,
 477         &io_is_busy_gov_pol.attr,
 478         NULL
 479 };
 480
 481 static struct attribute_group od_attr_group_gov_pol = {
 482         .attrs = dbs_attributes_gov_pol,
 483         .name = "ondemand",
 484 };
 485
 486 /************************** sysfs end ************************/
 487
 488 static int od_init(struct dbs_data *dbs_data, bool notify)
 489 {
 490         struct od_dbs_tuners *tuners;
 491         u64 idle_time;
 492         int cpu;
 493
 494         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 495         if (!tuners) {
 496                 pr_err("%s: kzalloc failed\n", __func__);
 497                 return -ENOMEM;
 498         }
 499
 500         cpu = get_cpu();
 501         idle_time = get_cpu_idle_time_us(cpu, NULL);
 502         put_cpu();
 503         if (idle_time != -1ULL) {
 504                 /* Idle micro accounting is supported. Use finer thresholds */
 505                 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 506                 /*
 507                  * In nohz/micro accounting case we set the minimum frequency
 508                  * not depending on HZ, but fixed (very low). The deferred
 509                  * timer might skip some samples if idle/sleeping as needed.
 510                 */
 511                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 512         } else {
 513                 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 514
 515                 /* For correct statistics, we need 10 ticks for each measure */
 516                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 517                         jiffies_to_usecs(10);
 518         }
 519
 520         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 521         tuners->ignore_nice_load = 0;
 522         tuners->powersave_bias = default_powersave_bias;
 523         tuners->io_is_busy = should_io_be_busy();
 524
 525         dbs_data->tuners = tuners;
 526         return 0;
 527 }
 528
 529 static void od_exit(struct dbs_data *dbs_data, bool notify)
 530 {
 531         kfree(dbs_data->tuners);
 532 }
 533
 534 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 535
 536 static struct od_ops od_ops = {
 537         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 538         .powersave_bias_target = generic_powersave_bias_target,
 539         .freq_increase = dbs_freq_increase,
 540 };
 541
 542 static struct dbs_governor od_dbs_gov = {
 543         .gov = {
 544                 .name = "ondemand",
 545                 .governor = cpufreq_governor_dbs,
 546                 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 547                 .owner = THIS_MODULE,
 548         },
 549         .governor = GOV_ONDEMAND,
 550         .attr_group_gov_sys = &od_attr_group_gov_sys,
 551         .attr_group_gov_pol = &od_attr_group_gov_pol,
 552         .get_cpu_cdbs = get_cpu_cdbs,
 553         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 554         .gov_dbs_timer = od_dbs_timer,
 555         .gov_check_cpu = od_check_cpu,
 556         .gov_ops = &od_ops,
 557         .init = od_init,
 558         .exit = od_exit,
 559 };
 560
 561 #define CPU_FREQ_GOV_ONDEMAND   (&od_dbs_gov.gov)
 562
 563 static void od_set_powersave_bias(unsigned int powersave_bias)
 564 {
 565         struct cpufreq_policy *policy;
 566         struct dbs_data *dbs_data;
 567         struct od_dbs_tuners *od_tuners;
 568         unsigned int cpu;
 569         cpumask_t done;
 570
 571         default_powersave_bias = powersave_bias;
 572         cpumask_clear(&done);
 573
 574         get_online_cpus();
 575         for_each_online_cpu(cpu) {
 576                 struct cpu_common_dbs_info *shared;
 577
 578                 if (cpumask_test_cpu(cpu, &done))
 579                         continue;
 580
 581                 shared = per_cpu(od_cpu_dbs_info, cpu).cdbs.shared;
 582                 if (!shared)
 583                         continue;
 584
 585                 policy = shared->policy;
 586                 cpumask_or(&done, &done, policy->cpus);
 587
 588                 if (policy->governor != CPU_FREQ_GOV_ONDEMAND)
 589                         continue;
 590
 591                 dbs_data = policy->governor_data;
 592                 od_tuners = dbs_data->tuners;
 593                 od_tuners->powersave_bias = default_powersave_bias;
 594         }
 595         put_online_cpus();
 596 }
 597
 598 void od_register_powersave_bias_handler(unsigned int (*f)
 599                 (struct cpufreq_policy *, unsigned int, unsigned int),
 600                 unsigned int powersave_bias)
 601 {
 602         od_ops.powersave_bias_target = f;
 603         od_set_powersave_bias(powersave_bias);
 604 }
 605 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 606
 607 void od_unregister_powersave_bias_handler(void)
 608 {
 609         od_ops.powersave_bias_target = generic_powersave_bias_target;
 610         od_set_powersave_bias(0);
 611 }
 612 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 613
 614 static int __init cpufreq_gov_dbs_init(void)
 615 {
 616         return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND);
 617 }
 618
 619 static void __exit cpufreq_gov_dbs_exit(void)
 620 {
 621         cpufreq_unregister_governor(CPU_FREQ_GOV_ONDEMAND);
 622 }
 623
 624 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 625 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 626 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 627         "Low Latency Frequency Transition capable processors");
 628 MODULE_LICENSE("GPL");
 629
 630 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 631 struct cpufreq_governor *cpufreq_default_governor(void)
 632 {
 633         return CPU_FREQ_GOV_ONDEMAND;
 634 }
 635
 636 fs_initcall(cpufreq_gov_dbs_init);
 637 #else
 638 module_init(cpufreq_gov_dbs_init);
 639 #endif
 640 module_exit(cpufreq_gov_dbs_exit);