config: tegra3: enable /dev mount with ACL
[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 DEF_SAMPLING_DOWN_FACTOR                (1)
34 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
35 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL       (3)
36 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
37 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
38 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
39 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
40
41 /*
42  * The polling frequency of this governor depends on the capability of
43  * the processor. Default polling frequency is 1000 times the transition
44  * latency of the processor. The governor will work on any processor with
45  * transition latency <= 10mS, using appropriate sampling
46  * rate.
47  * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
48  * this governor will not work.
49  * All times here are in uS.
50  */
51 #define MIN_SAMPLING_RATE_RATIO                 (2)
52
53 static unsigned int min_sampling_rate;
54
55 #define LATENCY_MULTIPLIER                      (1000)
56 #define MIN_LATENCY_MULTIPLIER                  (100)
57 #define TRANSITION_LATENCY_LIMIT                (10 * 1000 * 1000)
58
59 static void do_dbs_timer(struct work_struct *work);
60 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
61                                 unsigned int event);
62
63 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
64 static
65 #endif
66 struct cpufreq_governor cpufreq_gov_ondemand = {
67        .name                   = "ondemand",
68        .governor               = cpufreq_governor_dbs,
69        .max_transition_latency = TRANSITION_LATENCY_LIMIT,
70        .owner                  = THIS_MODULE,
71 };
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_iowait;
79         cputime64_t prev_cpu_wall;
80         cputime64_t prev_cpu_nice;
81         struct cpufreq_policy *cur_policy;
82         struct delayed_work work;
83         struct cpufreq_frequency_table *freq_table;
84         unsigned int freq_lo;
85         unsigned int freq_lo_jiffies;
86         unsigned int freq_hi_jiffies;
87         unsigned int rate_mult;
88         int cpu;
89         unsigned int sample_type:1;
90         /*
91          * percpu mutex that serializes governor limit change with
92          * do_dbs_timer invocation. We do not want do_dbs_timer to run
93          * when user is changing the governor or limits.
94          */
95         struct mutex timer_mutex;
96 };
97 static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
98
99 static unsigned int dbs_enable; /* number of CPUs using this policy */
100
101 /*
102  * dbs_mutex protects dbs_enable in governor start/stop.
103  */
104 static DEFINE_MUTEX(dbs_mutex);
105
106 static struct dbs_tuners {
107         unsigned int sampling_rate;
108         unsigned int up_threshold;
109         unsigned int down_differential;
110         unsigned int ignore_nice;
111         unsigned int sampling_down_factor;
112         unsigned int powersave_bias;
113         unsigned int io_is_busy;
114 } dbs_tuners_ins = {
115         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
116         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
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 = (cputime64_t)jiffies_to_usecs(cur_wall_time);
141
142         return (cputime64_t)jiffies_to_usecs(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 static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
156 {
157         u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
158
159         if (iowait_time == -1ULL)
160                 return 0;
161
162         return iowait_time;
163 }
164
165 /*
166  * Find right freq to be set now with powersave_bias on.
167  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
168  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
169  */
170 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
171                                           unsigned int freq_next,
172                                           unsigned int relation)
173 {
174         unsigned int freq_req, freq_reduc, freq_avg;
175         unsigned int freq_hi, freq_lo;
176         unsigned int index = 0;
177         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
178         struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
179                                                    policy->cpu);
180
181         if (!dbs_info->freq_table) {
182                 dbs_info->freq_lo = 0;
183                 dbs_info->freq_lo_jiffies = 0;
184                 return freq_next;
185         }
186
187         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
188                         relation, &index);
189         freq_req = dbs_info->freq_table[index].frequency;
190         freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
191         freq_avg = freq_req - freq_reduc;
192
193         /* Find freq bounds for freq_avg in freq_table */
194         index = 0;
195         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
196                         CPUFREQ_RELATION_H, &index);
197         freq_lo = dbs_info->freq_table[index].frequency;
198         index = 0;
199         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
200                         CPUFREQ_RELATION_L, &index);
201         freq_hi = dbs_info->freq_table[index].frequency;
202
203         /* Find out how long we have to be in hi and lo freqs */
204         if (freq_hi == freq_lo) {
205                 dbs_info->freq_lo = 0;
206                 dbs_info->freq_lo_jiffies = 0;
207                 return freq_lo;
208         }
209         jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
210         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
211         jiffies_hi += ((freq_hi - freq_lo) / 2);
212         jiffies_hi /= (freq_hi - freq_lo);
213         jiffies_lo = jiffies_total - jiffies_hi;
214         dbs_info->freq_lo = freq_lo;
215         dbs_info->freq_lo_jiffies = jiffies_lo;
216         dbs_info->freq_hi_jiffies = jiffies_hi;
217         return freq_hi;
218 }
219
220 static void ondemand_powersave_bias_init_cpu(int cpu)
221 {
222         struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
223         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
224         dbs_info->freq_lo = 0;
225 }
226
227 static void ondemand_powersave_bias_init(void)
228 {
229         int i;
230         for_each_online_cpu(i) {
231                 ondemand_powersave_bias_init_cpu(i);
232         }
233 }
234
235 /************************** sysfs interface ************************/
236
237 static ssize_t show_sampling_rate_min(struct kobject *kobj,
238                                       struct attribute *attr, char *buf)
239 {
240         return sprintf(buf, "%u\n", min_sampling_rate);
241 }
242
243 define_one_global_ro(sampling_rate_min);
244
245 /* cpufreq_ondemand Governor Tunables */
246 #define show_one(file_name, object)                                     \
247 static ssize_t show_##file_name                                         \
248 (struct kobject *kobj, struct attribute *attr, char *buf)              \
249 {                                                                       \
250         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
251 }
252 show_one(sampling_rate, sampling_rate);
253 show_one(io_is_busy, io_is_busy);
254 show_one(up_threshold, up_threshold);
255 show_one(sampling_down_factor, sampling_down_factor);
256 show_one(ignore_nice_load, ignore_nice);
257 show_one(powersave_bias, powersave_bias);
258
259 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
260                                    const char *buf, size_t count)
261 {
262         unsigned int input;
263         int ret;
264         ret = sscanf(buf, "%u", &input);
265         if (ret != 1)
266                 return -EINVAL;
267         dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
268         return count;
269 }
270
271 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
272                                    const char *buf, size_t count)
273 {
274         unsigned int input;
275         int ret;
276
277         ret = sscanf(buf, "%u", &input);
278         if (ret != 1)
279                 return -EINVAL;
280         dbs_tuners_ins.io_is_busy = !!input;
281         return count;
282 }
283
284 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
285                                   const char *buf, size_t count)
286 {
287         unsigned int input;
288         int ret;
289         ret = sscanf(buf, "%u", &input);
290
291         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
292                         input < MIN_FREQUENCY_UP_THRESHOLD) {
293                 return -EINVAL;
294         }
295         dbs_tuners_ins.up_threshold = input;
296         return count;
297 }
298
299 static ssize_t store_sampling_down_factor(struct kobject *a,
300                         struct attribute *b, const char *buf, size_t count)
301 {
302         unsigned int input, j;
303         int ret;
304         ret = sscanf(buf, "%u", &input);
305
306         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
307                 return -EINVAL;
308         dbs_tuners_ins.sampling_down_factor = input;
309
310         /* Reset down sampling multiplier in case it was active */
311         for_each_online_cpu(j) {
312                 struct cpu_dbs_info_s *dbs_info;
313                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
314                 dbs_info->rate_mult = 1;
315         }
316         return count;
317 }
318
319 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
320                                       const char *buf, size_t count)
321 {
322         unsigned int input;
323         int ret;
324
325         unsigned int j;
326
327         ret = sscanf(buf, "%u", &input);
328         if (ret != 1)
329                 return -EINVAL;
330
331         if (input > 1)
332                 input = 1;
333
334         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
335                 return count;
336         }
337         dbs_tuners_ins.ignore_nice = input;
338
339         /* we need to re-evaluate prev_cpu_idle */
340         for_each_online_cpu(j) {
341                 struct cpu_dbs_info_s *dbs_info;
342                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
343                 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
344                                                 &dbs_info->prev_cpu_wall);
345                 if (dbs_tuners_ins.ignore_nice)
346                         dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
347
348         }
349         return count;
350 }
351
352 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
353                                     const char *buf, size_t count)
354 {
355         unsigned int input;
356         int ret;
357         ret = sscanf(buf, "%u", &input);
358
359         if (ret != 1)
360                 return -EINVAL;
361
362         if (input > 1000)
363                 input = 1000;
364
365         dbs_tuners_ins.powersave_bias = input;
366         ondemand_powersave_bias_init();
367         return count;
368 }
369
370 define_one_global_rw(sampling_rate);
371 define_one_global_rw(io_is_busy);
372 define_one_global_rw(up_threshold);
373 define_one_global_rw(sampling_down_factor);
374 define_one_global_rw(ignore_nice_load);
375 define_one_global_rw(powersave_bias);
376
377 static struct attribute *dbs_attributes[] = {
378         &sampling_rate_min.attr,
379         &sampling_rate.attr,
380         &up_threshold.attr,
381         &sampling_down_factor.attr,
382         &ignore_nice_load.attr,
383         &powersave_bias.attr,
384         &io_is_busy.attr,
385         NULL
386 };
387
388 static struct attribute_group dbs_attr_group = {
389         .attrs = dbs_attributes,
390         .name = "ondemand",
391 };
392
393 /************************** sysfs end ************************/
394
395 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
396 {
397         if (dbs_tuners_ins.powersave_bias)
398                 freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
399         else if (p->cur == p->max)
400                 return;
401
402         __cpufreq_driver_target(p, freq, dbs_tuners_ins.powersave_bias ?
403                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
404 }
405
406 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
407 {
408         unsigned int max_load_freq;
409
410         struct cpufreq_policy *policy;
411         unsigned int j;
412
413         this_dbs_info->freq_lo = 0;
414         policy = this_dbs_info->cur_policy;
415
416         /*
417          * Every sampling_rate, we check, if current idle time is less
418          * than 20% (default), then we try to increase frequency
419          * Every sampling_rate, we look for a the lowest
420          * frequency which can sustain the load while keeping idle time over
421          * 30%. If such a frequency exist, we try to decrease to this frequency.
422          *
423          * Any frequency increase takes it to the maximum frequency.
424          * Frequency reduction happens at minimum steps of
425          * 5% (default) of current frequency
426          */
427
428         /* Get Absolute Load - in terms of freq */
429         max_load_freq = 0;
430
431         for_each_cpu(j, policy->cpus) {
432                 struct cpu_dbs_info_s *j_dbs_info;
433                 cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
434                 unsigned int idle_time, wall_time, iowait_time;
435                 unsigned int load, load_freq;
436                 int freq_avg;
437
438                 j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
439
440                 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
441                 cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
442
443                 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
444                                 j_dbs_info->prev_cpu_wall);
445                 j_dbs_info->prev_cpu_wall = cur_wall_time;
446
447                 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
448                                 j_dbs_info->prev_cpu_idle);
449                 j_dbs_info->prev_cpu_idle = cur_idle_time;
450
451                 iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
452                                 j_dbs_info->prev_cpu_iowait);
453                 j_dbs_info->prev_cpu_iowait = cur_iowait_time;
454
455                 if (dbs_tuners_ins.ignore_nice) {
456                         cputime64_t cur_nice;
457                         unsigned long cur_nice_jiffies;
458
459                         cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
460                                          j_dbs_info->prev_cpu_nice);
461                         /*
462                          * Assumption: nice time between sampling periods will
463                          * be less than 2^32 jiffies for 32 bit sys
464                          */
465                         cur_nice_jiffies = (unsigned long)
466                                         cputime64_to_jiffies64(cur_nice);
467
468                         j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
469                         idle_time += jiffies_to_usecs(cur_nice_jiffies);
470                 }
471
472                 /*
473                  * For the purpose of ondemand, waiting for disk IO is an
474                  * indication that you're performance critical, and not that
475                  * the system is actually idle. So subtract the iowait time
476                  * from the cpu idle time.
477                  */
478
479                 if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
480                         idle_time -= iowait_time;
481
482                 if (unlikely(!wall_time || wall_time < idle_time))
483                         continue;
484
485                 load = 100 * (wall_time - idle_time) / wall_time;
486
487                 freq_avg = __cpufreq_driver_getavg(policy, j);
488                 if (freq_avg <= 0)
489                         freq_avg = policy->cur;
490
491                 load_freq = load * freq_avg;
492                 if (load_freq > max_load_freq)
493                         max_load_freq = load_freq;
494         }
495
496         /* Check for frequency increase */
497         if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
498                 /* If switching to max speed, apply sampling_down_factor */
499                 if (policy->cur < policy->max)
500                         this_dbs_info->rate_mult =
501                                 dbs_tuners_ins.sampling_down_factor;
502                 dbs_freq_increase(policy, policy->max);
503                 return;
504         }
505
506         /* Check for frequency decrease */
507         /* if we cannot reduce the frequency anymore, break out early */
508         if (policy->cur == policy->min)
509                 return;
510
511         /*
512          * The optimal frequency is the frequency that is the lowest that
513          * can support the current CPU usage without triggering the up
514          * policy. To be safe, we focus 10 points under the threshold.
515          */
516         if (max_load_freq <
517             (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
518              policy->cur) {
519                 unsigned int freq_next;
520                 freq_next = max_load_freq /
521                                 (dbs_tuners_ins.up_threshold -
522                                  dbs_tuners_ins.down_differential);
523
524                 /* No longer fully busy, reset rate_mult */
525                 this_dbs_info->rate_mult = 1;
526
527                 if (freq_next < policy->min)
528                         freq_next = policy->min;
529
530                 if (!dbs_tuners_ins.powersave_bias) {
531                         __cpufreq_driver_target(policy, freq_next,
532                                         CPUFREQ_RELATION_L);
533                 } else {
534                         int freq = powersave_bias_target(policy, freq_next,
535                                         CPUFREQ_RELATION_L);
536                         __cpufreq_driver_target(policy, freq,
537                                 CPUFREQ_RELATION_L);
538                 }
539         }
540 }
541
542 static void do_dbs_timer(struct work_struct *work)
543 {
544         struct cpu_dbs_info_s *dbs_info =
545                 container_of(work, struct cpu_dbs_info_s, work.work);
546         unsigned int cpu = dbs_info->cpu;
547         int sample_type = dbs_info->sample_type;
548
549         int delay;
550
551         mutex_lock(&dbs_info->timer_mutex);
552
553         /* Common NORMAL_SAMPLE setup */
554         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
555         if (!dbs_tuners_ins.powersave_bias ||
556             sample_type == DBS_NORMAL_SAMPLE) {
557                 dbs_check_cpu(dbs_info);
558                 if (dbs_info->freq_lo) {
559                         /* Setup timer for SUB_SAMPLE */
560                         dbs_info->sample_type = DBS_SUB_SAMPLE;
561                         delay = dbs_info->freq_hi_jiffies;
562                 } else {
563                         /* We want all CPUs to do sampling nearly on
564                          * same jiffy
565                          */
566                         delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
567                                 * dbs_info->rate_mult);
568
569                         if (num_online_cpus() > 1)
570                                 delay -= jiffies % delay;
571                 }
572         } else {
573                 __cpufreq_driver_target(dbs_info->cur_policy,
574                         dbs_info->freq_lo, CPUFREQ_RELATION_H);
575                 delay = dbs_info->freq_lo_jiffies;
576         }
577         schedule_delayed_work_on(cpu, &dbs_info->work, delay);
578         mutex_unlock(&dbs_info->timer_mutex);
579 }
580
581 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
582 {
583         /* We want all CPUs to do sampling nearly on same jiffy */
584         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
585
586         if (num_online_cpus() > 1)
587                 delay -= jiffies % delay;
588
589         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
590         INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
591         schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work, delay);
592 }
593
594 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
595 {
596         cancel_delayed_work_sync(&dbs_info->work);
597 }
598
599 /*
600  * Not all CPUs want IO time to be accounted as busy; this dependson how
601  * efficient idling at a higher frequency/voltage is.
602  * Pavel Machek says this is not so for various generations of AMD and old
603  * Intel systems.
604  * Mike Chan (androidlcom) calis this is also not true for ARM.
605  * Because of this, whitelist specific known (series) of CPUs by default, and
606  * leave all others up to the user.
607  */
608 static int should_io_be_busy(void)
609 {
610 #if defined(CONFIG_X86)
611         /*
612          * For Intel, Core 2 (model 15) andl later have an efficient idle.
613          */
614         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
615             boot_cpu_data.x86 == 6 &&
616             boot_cpu_data.x86_model >= 15)
617                 return 1;
618 #endif
619         return 0;
620 }
621
622 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
623                                    unsigned int event)
624 {
625         unsigned int cpu = policy->cpu;
626         struct cpu_dbs_info_s *this_dbs_info;
627         unsigned int j;
628         int rc;
629
630         this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
631
632         switch (event) {
633         case CPUFREQ_GOV_START:
634                 if ((!cpu_online(cpu)) || (!policy->cur))
635                         return -EINVAL;
636
637                 mutex_lock(&dbs_mutex);
638
639                 dbs_enable++;
640                 for_each_cpu(j, policy->cpus) {
641                         struct cpu_dbs_info_s *j_dbs_info;
642                         j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
643                         j_dbs_info->cur_policy = policy;
644
645                         j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
646                                                 &j_dbs_info->prev_cpu_wall);
647                         if (dbs_tuners_ins.ignore_nice) {
648                                 j_dbs_info->prev_cpu_nice =
649                                                 kstat_cpu(j).cpustat.nice;
650                         }
651                 }
652                 this_dbs_info->cpu = cpu;
653                 this_dbs_info->rate_mult = 1;
654                 ondemand_powersave_bias_init_cpu(cpu);
655                 /*
656                  * Start the timerschedule work, when this governor
657                  * is used for first time
658                  */
659                 if (dbs_enable == 1) {
660                         unsigned int latency;
661
662                         rc = sysfs_create_group(cpufreq_global_kobject,
663                                                 &dbs_attr_group);
664                         if (rc) {
665                                 mutex_unlock(&dbs_mutex);
666                                 return rc;
667                         }
668
669                         /* policy latency is in nS. Convert it to uS first */
670                         latency = policy->cpuinfo.transition_latency / 1000;
671                         if (latency == 0)
672                                 latency = 1;
673                         /* Bring kernel and HW constraints together */
674                         min_sampling_rate = max(min_sampling_rate,
675                                         MIN_LATENCY_MULTIPLIER * latency);
676                         dbs_tuners_ins.sampling_rate =
677                                 max(min_sampling_rate,
678                                     latency * LATENCY_MULTIPLIER);
679                         dbs_tuners_ins.io_is_busy = should_io_be_busy();
680                 }
681                 mutex_unlock(&dbs_mutex);
682
683                 mutex_init(&this_dbs_info->timer_mutex);
684                 dbs_timer_init(this_dbs_info);
685                 break;
686
687         case CPUFREQ_GOV_STOP:
688                 dbs_timer_exit(this_dbs_info);
689
690                 mutex_lock(&dbs_mutex);
691                 mutex_destroy(&this_dbs_info->timer_mutex);
692                 dbs_enable--;
693                 if (!dbs_enable)
694                         sysfs_remove_group(cpufreq_global_kobject,
695                                            &dbs_attr_group);
696                 mutex_unlock(&dbs_mutex);
697                 break;
698
699         case CPUFREQ_GOV_LIMITS:
700                 mutex_lock(&this_dbs_info->timer_mutex);
701                 if (policy->max < this_dbs_info->cur_policy->cur)
702                         __cpufreq_driver_target(this_dbs_info->cur_policy,
703                                 policy->max, CPUFREQ_RELATION_H);
704                 else if (policy->min > this_dbs_info->cur_policy->cur)
705                         __cpufreq_driver_target(this_dbs_info->cur_policy,
706                                 policy->min, CPUFREQ_RELATION_L);
707                 mutex_unlock(&this_dbs_info->timer_mutex);
708                 break;
709         }
710         return 0;
711 }
712
713 static int __init cpufreq_gov_dbs_init(void)
714 {
715         cputime64_t wall;
716         u64 idle_time;
717         int cpu = get_cpu();
718
719         idle_time = get_cpu_idle_time_us(cpu, &wall);
720         put_cpu();
721         if (idle_time != -1ULL) {
722                 /* Idle micro accounting is supported. Use finer thresholds */
723                 dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
724                 dbs_tuners_ins.down_differential =
725                                         MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
726                 /*
727                  * In no_hz/micro accounting case we set the minimum frequency
728                  * not depending on HZ, but fixed (very low). The deferred
729                  * timer might skip some samples if idle/sleeping as needed.
730                 */
731                 min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
732         } else {
733                 /* For correct statistics, we need 10 ticks for each measure */
734                 min_sampling_rate =
735                         MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
736         }
737
738         return cpufreq_register_governor(&cpufreq_gov_ondemand);
739 }
740
741 static void __exit cpufreq_gov_dbs_exit(void)
742 {
743         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
744 }
745
746
747 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
748 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
749 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
750         "Low Latency Frequency Transition capable processors");
751 MODULE_LICENSE("GPL");
752
753 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
754 fs_initcall(cpufreq_gov_dbs_init);
755 #else
756 module_init(cpufreq_gov_dbs_init);
757 #endif
758 module_exit(cpufreq_gov_dbs_exit);