cpumask: alloc zeroed cpumask for static cpumask_var_ts
[linux-2.6.git] / 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 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/cpufreq.h>
17 #include <linux/cpu.h>
18 #include <linux/jiffies.h>
19 #include <linux/kernel_stat.h>
20 #include <linux/mutex.h>
21 #include <linux/hrtimer.h>
22 #include <linux/tick.h>
23 #include <linux/ktime.h>
24 #include <linux/sched.h>
25
26 /*
27  * dbs is used in this file as a shortform for demandbased switching
28  * It helps to keep variable names smaller, simpler
29  */
30
31 #define DEF_FREQUENCY_DOWN_DIFFERENTIAL         (10)
32 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
33 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL       (3)
34 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
35 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
36 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
37
38 /*
39  * The polling frequency of this governor depends on the capability of
40  * the processor. Default polling frequency is 1000 times the transition
41  * latency of the processor. The governor will work on any processor with
42  * transition latency <= 10mS, using appropriate sampling
43  * rate.
44  * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
45  * this governor will not work.
46  * All times here are in uS.
47  */
48 static unsigned int def_sampling_rate;
49 #define MIN_SAMPLING_RATE_RATIO                 (2)
50 /* for correct statistics, we need at least 10 ticks between each measure */
51 #define MIN_STAT_SAMPLING_RATE                  \
52                         (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
53 #define MIN_SAMPLING_RATE                       \
54                         (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
55 /* Above MIN_SAMPLING_RATE will vanish with its sysfs file soon
56  * Define the minimal settable sampling rate to the greater of:
57  *   - "HW transition latency" * 100 (same as default sampling / 10)
58  *   - MIN_STAT_SAMPLING_RATE
59  * To avoid that userspace shoots itself.
60 */
61 static unsigned int minimum_sampling_rate(void)
62 {
63         return max(def_sampling_rate / 10, MIN_STAT_SAMPLING_RATE);
64 }
65
66 /* This will also vanish soon with removing sampling_rate_max */
67 #define MAX_SAMPLING_RATE                       (500 * def_sampling_rate)
68 #define LATENCY_MULTIPLIER                      (1000)
69 #define TRANSITION_LATENCY_LIMIT                (10 * 1000 * 1000)
70
71 static void do_dbs_timer(struct work_struct *work);
72
73 /* Sampling types */
74 enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
75
76 struct cpu_dbs_info_s {
77         cputime64_t prev_cpu_idle;
78         cputime64_t prev_cpu_wall;
79         cputime64_t prev_cpu_nice;
80         struct cpufreq_policy *cur_policy;
81         struct delayed_work work;
82         struct cpufreq_frequency_table *freq_table;
83         unsigned int freq_lo;
84         unsigned int freq_lo_jiffies;
85         unsigned int freq_hi_jiffies;
86         int cpu;
87         unsigned int enable:1,
88                 sample_type:1;
89 };
90 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
91
92 static unsigned int dbs_enable; /* number of CPUs using this policy */
93
94 /*
95  * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
96  * lock and dbs_mutex. cpu_hotplug lock should always be held before
97  * dbs_mutex. If any function that can potentially take cpu_hotplug lock
98  * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
99  * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
100  * is recursive for the same process. -Venki
101  * DEADLOCK ALERT! (2) : do_dbs_timer() must not take the dbs_mutex, because it
102  * would deadlock with cancel_delayed_work_sync(), which is needed for proper
103  * raceless workqueue teardown.
104  */
105 static DEFINE_MUTEX(dbs_mutex);
106
107 static struct workqueue_struct  *kondemand_wq;
108
109 static struct dbs_tuners {
110         unsigned int sampling_rate;
111         unsigned int up_threshold;
112         unsigned int down_differential;
113         unsigned int ignore_nice;
114         unsigned int powersave_bias;
115 } dbs_tuners_ins = {
116         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
117         .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
118         .ignore_nice = 0,
119         .powersave_bias = 0,
120 };
121
122 static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
123                                                         cputime64_t *wall)
124 {
125         cputime64_t idle_time;
126         cputime64_t cur_wall_time;
127         cputime64_t busy_time;
128
129         cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
130         busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
131                         kstat_cpu(cpu).cpustat.system);
132
133         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
134         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
135         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
136         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
137
138         idle_time = cputime64_sub(cur_wall_time, busy_time);
139         if (wall)
140                 *wall = cur_wall_time;
141
142         return idle_time;
143 }
144
145 static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
146 {
147         u64 idle_time = get_cpu_idle_time_us(cpu, wall);
148
149         if (idle_time == -1ULL)
150                 return get_cpu_idle_time_jiffy(cpu, wall);
151
152         return idle_time;
153 }
154
155 /*
156  * Find right freq to be set now with powersave_bias on.
157  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
158  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
159  */
160 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
161                                           unsigned int freq_next,
162                                           unsigned int relation)
163 {
164         unsigned int freq_req, freq_reduc, freq_avg;
165         unsigned int freq_hi, freq_lo;
166         unsigned int index = 0;
167         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
168         struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, policy->cpu);
169
170         if (!dbs_info->freq_table) {
171                 dbs_info->freq_lo = 0;
172                 dbs_info->freq_lo_jiffies = 0;
173                 return freq_next;
174         }
175
176         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
177                         relation, &index);
178         freq_req = dbs_info->freq_table[index].frequency;
179         freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
180         freq_avg = freq_req - freq_reduc;
181
182         /* Find freq bounds for freq_avg in freq_table */
183         index = 0;
184         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
185                         CPUFREQ_RELATION_H, &index);
186         freq_lo = dbs_info->freq_table[index].frequency;
187         index = 0;
188         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
189                         CPUFREQ_RELATION_L, &index);
190         freq_hi = dbs_info->freq_table[index].frequency;
191
192         /* Find out how long we have to be in hi and lo freqs */
193         if (freq_hi == freq_lo) {
194                 dbs_info->freq_lo = 0;
195                 dbs_info->freq_lo_jiffies = 0;
196                 return freq_lo;
197         }
198         jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
199         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
200         jiffies_hi += ((freq_hi - freq_lo) / 2);
201         jiffies_hi /= (freq_hi - freq_lo);
202         jiffies_lo = jiffies_total - jiffies_hi;
203         dbs_info->freq_lo = freq_lo;
204         dbs_info->freq_lo_jiffies = jiffies_lo;
205         dbs_info->freq_hi_jiffies = jiffies_hi;
206         return freq_hi;
207 }
208
209 static void ondemand_powersave_bias_init(void)
210 {
211         int i;
212         for_each_online_cpu(i) {
213                 struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i);
214                 dbs_info->freq_table = cpufreq_frequency_get_table(i);
215                 dbs_info->freq_lo = 0;
216         }
217 }
218
219 /************************** sysfs interface ************************/
220 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
221 {
222         static int print_once;
223
224         if (!print_once) {
225                 printk(KERN_INFO "CPUFREQ: ondemand sampling_rate_max "
226                        "sysfs file is deprecated - used by: %s\n",
227                        current->comm);
228                 print_once = 1;
229         }
230         return sprintf(buf, "%u\n", MAX_SAMPLING_RATE);
231 }
232
233 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
234 {
235         static int print_once;
236
237         if (!print_once) {
238                 printk(KERN_INFO "CPUFREQ: ondemand sampling_rate_min "
239                        "sysfs file is deprecated - used by: %s\n",
240                        current->comm);
241                 print_once = 1;
242         }
243         return sprintf(buf, "%u\n", MIN_SAMPLING_RATE);
244 }
245
246 #define define_one_ro(_name)            \
247 static struct freq_attr _name =         \
248 __ATTR(_name, 0444, show_##_name, NULL)
249
250 define_one_ro(sampling_rate_max);
251 define_one_ro(sampling_rate_min);
252
253 /* cpufreq_ondemand Governor Tunables */
254 #define show_one(file_name, object)                                     \
255 static ssize_t show_##file_name                                         \
256 (struct cpufreq_policy *unused, char *buf)                              \
257 {                                                                       \
258         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
259 }
260 show_one(sampling_rate, sampling_rate);
261 show_one(up_threshold, up_threshold);
262 show_one(ignore_nice_load, ignore_nice);
263 show_one(powersave_bias, powersave_bias);
264
265 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
266                 const char *buf, size_t count)
267 {
268         unsigned int input;
269         int ret;
270         ret = sscanf(buf, "%u", &input);
271
272         mutex_lock(&dbs_mutex);
273         if (ret != 1) {
274                 mutex_unlock(&dbs_mutex);
275                 return -EINVAL;
276         }
277         dbs_tuners_ins.sampling_rate = max(input, minimum_sampling_rate());
278         mutex_unlock(&dbs_mutex);
279
280         return count;
281 }
282
283 static ssize_t store_up_threshold(struct cpufreq_policy *unused,
284                 const char *buf, size_t count)
285 {
286         unsigned int input;
287         int ret;
288         ret = sscanf(buf, "%u", &input);
289
290         mutex_lock(&dbs_mutex);
291         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
292                         input < MIN_FREQUENCY_UP_THRESHOLD) {
293                 mutex_unlock(&dbs_mutex);
294                 return -EINVAL;
295         }
296
297         dbs_tuners_ins.up_threshold = input;
298         mutex_unlock(&dbs_mutex);
299
300         return count;
301 }
302
303 static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
304                 const char *buf, size_t count)
305 {
306         unsigned int input;
307         int ret;
308
309         unsigned int j;
310
311         ret = sscanf(buf, "%u", &input);
312         if (ret != 1)
313                 return -EINVAL;
314
315         if (input > 1)
316                 input = 1;
317
318         mutex_lock(&dbs_mutex);
319         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
320                 mutex_unlock(&dbs_mutex);
321                 return count;
322         }
323         dbs_tuners_ins.ignore_nice = input;
324
325         /* we need to re-evaluate prev_cpu_idle */
326         for_each_online_cpu(j) {
327                 struct cpu_dbs_info_s *dbs_info;
328                 dbs_info = &per_cpu(cpu_dbs_info, j);
329                 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
330                                                 &dbs_info->prev_cpu_wall);
331                 if (dbs_tuners_ins.ignore_nice)
332                         dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
333
334         }
335         mutex_unlock(&dbs_mutex);
336
337         return count;
338 }
339
340 static ssize_t store_powersave_bias(struct cpufreq_policy *unused,
341                 const char *buf, size_t count)
342 {
343         unsigned int input;
344         int ret;
345         ret = sscanf(buf, "%u", &input);
346
347         if (ret != 1)
348                 return -EINVAL;
349
350         if (input > 1000)
351                 input = 1000;
352
353         mutex_lock(&dbs_mutex);
354         dbs_tuners_ins.powersave_bias = input;
355         ondemand_powersave_bias_init();
356         mutex_unlock(&dbs_mutex);
357
358         return count;
359 }
360
361 #define define_one_rw(_name) \
362 static struct freq_attr _name = \
363 __ATTR(_name, 0644, show_##_name, store_##_name)
364
365 define_one_rw(sampling_rate);
366 define_one_rw(up_threshold);
367 define_one_rw(ignore_nice_load);
368 define_one_rw(powersave_bias);
369
370 static struct attribute *dbs_attributes[] = {
371         &sampling_rate_max.attr,
372         &sampling_rate_min.attr,
373         &sampling_rate.attr,
374         &up_threshold.attr,
375         &ignore_nice_load.attr,
376         &powersave_bias.attr,
377         NULL
378 };
379
380 static struct attribute_group dbs_attr_group = {
381         .attrs = dbs_attributes,
382         .name = "ondemand",
383 };
384
385 /************************** sysfs end ************************/
386
387 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
388 {
389         unsigned int max_load_freq;
390
391         struct cpufreq_policy *policy;
392         unsigned int j;
393
394         if (!this_dbs_info->enable)
395                 return;
396
397         this_dbs_info->freq_lo = 0;
398         policy = this_dbs_info->cur_policy;
399
400         /*
401          * Every sampling_rate, we check, if current idle time is less
402          * than 20% (default), then we try to increase frequency
403          * Every sampling_rate, we look for a the lowest
404          * frequency which can sustain the load while keeping idle time over
405          * 30%. If such a frequency exist, we try to decrease to this frequency.
406          *
407          * Any frequency increase takes it to the maximum frequency.
408          * Frequency reduction happens at minimum steps of
409          * 5% (default) of current frequency
410          */
411
412         /* Get Absolute Load - in terms of freq */
413         max_load_freq = 0;
414
415         for_each_cpu(j, policy->cpus) {
416                 struct cpu_dbs_info_s *j_dbs_info;
417                 cputime64_t cur_wall_time, cur_idle_time;
418                 unsigned int idle_time, wall_time;
419                 unsigned int load, load_freq;
420                 int freq_avg;
421
422                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
423
424                 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
425
426                 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
427                                 j_dbs_info->prev_cpu_wall);
428                 j_dbs_info->prev_cpu_wall = cur_wall_time;
429
430                 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
431                                 j_dbs_info->prev_cpu_idle);
432                 j_dbs_info->prev_cpu_idle = cur_idle_time;
433
434                 if (dbs_tuners_ins.ignore_nice) {
435                         cputime64_t cur_nice;
436                         unsigned long cur_nice_jiffies;
437
438                         cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
439                                          j_dbs_info->prev_cpu_nice);
440                         /*
441                          * Assumption: nice time between sampling periods will
442                          * be less than 2^32 jiffies for 32 bit sys
443                          */
444                         cur_nice_jiffies = (unsigned long)
445                                         cputime64_to_jiffies64(cur_nice);
446
447                         j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
448                         idle_time += jiffies_to_usecs(cur_nice_jiffies);
449                 }
450
451                 if (unlikely(!wall_time || wall_time < idle_time))
452                         continue;
453
454                 load = 100 * (wall_time - idle_time) / wall_time;
455
456                 freq_avg = __cpufreq_driver_getavg(policy, j);
457                 if (freq_avg <= 0)
458                         freq_avg = policy->cur;
459
460                 load_freq = load * freq_avg;
461                 if (load_freq > max_load_freq)
462                         max_load_freq = load_freq;
463         }
464
465         /* Check for frequency increase */
466         if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
467                 /* if we are already at full speed then break out early */
468                 if (!dbs_tuners_ins.powersave_bias) {
469                         if (policy->cur == policy->max)
470                                 return;
471
472                         __cpufreq_driver_target(policy, policy->max,
473                                 CPUFREQ_RELATION_H);
474                 } else {
475                         int freq = powersave_bias_target(policy, policy->max,
476                                         CPUFREQ_RELATION_H);
477                         __cpufreq_driver_target(policy, freq,
478                                 CPUFREQ_RELATION_L);
479                 }
480                 return;
481         }
482
483         /* Check for frequency decrease */
484         /* if we cannot reduce the frequency anymore, break out early */
485         if (policy->cur == policy->min)
486                 return;
487
488         /*
489          * The optimal frequency is the frequency that is the lowest that
490          * can support the current CPU usage without triggering the up
491          * policy. To be safe, we focus 10 points under the threshold.
492          */
493         if (max_load_freq <
494             (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
495              policy->cur) {
496                 unsigned int freq_next;
497                 freq_next = max_load_freq /
498                                 (dbs_tuners_ins.up_threshold -
499                                  dbs_tuners_ins.down_differential);
500
501                 if (!dbs_tuners_ins.powersave_bias) {
502                         __cpufreq_driver_target(policy, freq_next,
503                                         CPUFREQ_RELATION_L);
504                 } else {
505                         int freq = powersave_bias_target(policy, freq_next,
506                                         CPUFREQ_RELATION_L);
507                         __cpufreq_driver_target(policy, freq,
508                                 CPUFREQ_RELATION_L);
509                 }
510         }
511 }
512
513 static void do_dbs_timer(struct work_struct *work)
514 {
515         struct cpu_dbs_info_s *dbs_info =
516                 container_of(work, struct cpu_dbs_info_s, work.work);
517         unsigned int cpu = dbs_info->cpu;
518         int sample_type = dbs_info->sample_type;
519
520         /* We want all CPUs to do sampling nearly on same jiffy */
521         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
522
523         delay -= jiffies % delay;
524
525         if (lock_policy_rwsem_write(cpu) < 0)
526                 return;
527
528         if (!dbs_info->enable) {
529                 unlock_policy_rwsem_write(cpu);
530                 return;
531         }
532
533         /* Common NORMAL_SAMPLE setup */
534         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
535         if (!dbs_tuners_ins.powersave_bias ||
536             sample_type == DBS_NORMAL_SAMPLE) {
537                 dbs_check_cpu(dbs_info);
538                 if (dbs_info->freq_lo) {
539                         /* Setup timer for SUB_SAMPLE */
540                         dbs_info->sample_type = DBS_SUB_SAMPLE;
541                         delay = dbs_info->freq_hi_jiffies;
542                 }
543         } else {
544                 __cpufreq_driver_target(dbs_info->cur_policy,
545                         dbs_info->freq_lo, CPUFREQ_RELATION_H);
546         }
547         queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
548         unlock_policy_rwsem_write(cpu);
549 }
550
551 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
552 {
553         /* We want all CPUs to do sampling nearly on same jiffy */
554         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
555         delay -= jiffies % delay;
556
557         dbs_info->enable = 1;
558         ondemand_powersave_bias_init();
559         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
560         INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
561         queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work,
562                 delay);
563 }
564
565 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
566 {
567         dbs_info->enable = 0;
568         cancel_delayed_work_sync(&dbs_info->work);
569 }
570
571 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
572                                    unsigned int event)
573 {
574         unsigned int cpu = policy->cpu;
575         struct cpu_dbs_info_s *this_dbs_info;
576         unsigned int j;
577         int rc;
578
579         this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
580
581         switch (event) {
582         case CPUFREQ_GOV_START:
583                 if ((!cpu_online(cpu)) || (!policy->cur))
584                         return -EINVAL;
585
586                 if (this_dbs_info->enable) /* Already enabled */
587                         break;
588
589                 mutex_lock(&dbs_mutex);
590                 dbs_enable++;
591
592                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
593                 if (rc) {
594                         dbs_enable--;
595                         mutex_unlock(&dbs_mutex);
596                         return rc;
597                 }
598
599                 for_each_cpu(j, policy->cpus) {
600                         struct cpu_dbs_info_s *j_dbs_info;
601                         j_dbs_info = &per_cpu(cpu_dbs_info, j);
602                         j_dbs_info->cur_policy = policy;
603
604                         j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
605                                                 &j_dbs_info->prev_cpu_wall);
606                         if (dbs_tuners_ins.ignore_nice) {
607                                 j_dbs_info->prev_cpu_nice =
608                                                 kstat_cpu(j).cpustat.nice;
609                         }
610                 }
611                 this_dbs_info->cpu = cpu;
612                 /*
613                  * Start the timerschedule work, when this governor
614                  * is used for first time
615                  */
616                 if (dbs_enable == 1) {
617                         unsigned int latency;
618                         /* policy latency is in nS. Convert it to uS first */
619                         latency = policy->cpuinfo.transition_latency / 1000;
620                         if (latency == 0)
621                                 latency = 1;
622
623                         def_sampling_rate =
624                                 max(latency * LATENCY_MULTIPLIER,
625                                     MIN_STAT_SAMPLING_RATE);
626
627                         dbs_tuners_ins.sampling_rate = def_sampling_rate;
628                 }
629                 dbs_timer_init(this_dbs_info);
630
631                 mutex_unlock(&dbs_mutex);
632                 break;
633
634         case CPUFREQ_GOV_STOP:
635                 mutex_lock(&dbs_mutex);
636                 dbs_timer_exit(this_dbs_info);
637                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
638                 dbs_enable--;
639                 mutex_unlock(&dbs_mutex);
640
641                 break;
642
643         case CPUFREQ_GOV_LIMITS:
644                 mutex_lock(&dbs_mutex);
645                 if (policy->max < this_dbs_info->cur_policy->cur)
646                         __cpufreq_driver_target(this_dbs_info->cur_policy,
647                                 policy->max, CPUFREQ_RELATION_H);
648                 else if (policy->min > this_dbs_info->cur_policy->cur)
649                         __cpufreq_driver_target(this_dbs_info->cur_policy,
650                                 policy->min, CPUFREQ_RELATION_L);
651                 mutex_unlock(&dbs_mutex);
652                 break;
653         }
654         return 0;
655 }
656
657 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
658 static
659 #endif
660 struct cpufreq_governor cpufreq_gov_ondemand = {
661         .name                   = "ondemand",
662         .governor               = cpufreq_governor_dbs,
663         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
664         .owner                  = THIS_MODULE,
665 };
666
667 static int __init cpufreq_gov_dbs_init(void)
668 {
669         int err;
670         cputime64_t wall;
671         u64 idle_time;
672         int cpu = get_cpu();
673
674         idle_time = get_cpu_idle_time_us(cpu, &wall);
675         put_cpu();
676         if (idle_time != -1ULL) {
677                 /* Idle micro accounting is supported. Use finer thresholds */
678                 dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
679                 dbs_tuners_ins.down_differential =
680                                         MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
681         }
682
683         kondemand_wq = create_workqueue("kondemand");
684         if (!kondemand_wq) {
685                 printk(KERN_ERR "Creation of kondemand failed\n");
686                 return -EFAULT;
687         }
688         err = cpufreq_register_governor(&cpufreq_gov_ondemand);
689         if (err)
690                 destroy_workqueue(kondemand_wq);
691
692         return err;
693 }
694
695 static void __exit cpufreq_gov_dbs_exit(void)
696 {
697         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
698         destroy_workqueue(kondemand_wq);
699 }
700
701
702 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
703 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
704 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
705         "Low Latency Frequency Transition capable processors");
706 MODULE_LICENSE("GPL");
707
708 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
709 fs_initcall(cpufreq_gov_dbs_init);
710 #else
711 module_init(cpufreq_gov_dbs_init);
712 #endif
713 module_exit(cpufreq_gov_dbs_exit);