cpufreq: OMAP: notify even with bad boot frequency
[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, NULL);
148
149         if (idle_time == -1ULL)
150                 return get_cpu_idle_time_jiffy(cpu, wall);
151         else
152                 idle_time += get_cpu_iowait_time_us(cpu, wall);
153
154         return idle_time;
155 }
156
157 static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
158 {
159         u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
160
161         if (iowait_time == -1ULL)
162                 return 0;
163
164         return iowait_time;
165 }
166
167 /*
168  * Find right freq to be set now with powersave_bias on.
169  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
170  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
171  */
172 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
173                                           unsigned int freq_next,
174                                           unsigned int relation)
175 {
176         unsigned int freq_req, freq_reduc, freq_avg;
177         unsigned int freq_hi, freq_lo;
178         unsigned int index = 0;
179         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
180         struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
181                                                    policy->cpu);
182
183         if (!dbs_info->freq_table) {
184                 dbs_info->freq_lo = 0;
185                 dbs_info->freq_lo_jiffies = 0;
186                 return freq_next;
187         }
188
189         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
190                         relation, &index);
191         freq_req = dbs_info->freq_table[index].frequency;
192         freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
193         freq_avg = freq_req - freq_reduc;
194
195         /* Find freq bounds for freq_avg in freq_table */
196         index = 0;
197         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
198                         CPUFREQ_RELATION_H, &index);
199         freq_lo = dbs_info->freq_table[index].frequency;
200         index = 0;
201         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
202                         CPUFREQ_RELATION_L, &index);
203         freq_hi = dbs_info->freq_table[index].frequency;
204
205         /* Find out how long we have to be in hi and lo freqs */
206         if (freq_hi == freq_lo) {
207                 dbs_info->freq_lo = 0;
208                 dbs_info->freq_lo_jiffies = 0;
209                 return freq_lo;
210         }
211         jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
212         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
213         jiffies_hi += ((freq_hi - freq_lo) / 2);
214         jiffies_hi /= (freq_hi - freq_lo);
215         jiffies_lo = jiffies_total - jiffies_hi;
216         dbs_info->freq_lo = freq_lo;
217         dbs_info->freq_lo_jiffies = jiffies_lo;
218         dbs_info->freq_hi_jiffies = jiffies_hi;
219         return freq_hi;
220 }
221
222 static void ondemand_powersave_bias_init_cpu(int cpu)
223 {
224         struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
225         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
226         dbs_info->freq_lo = 0;
227 }
228
229 static void ondemand_powersave_bias_init(void)
230 {
231         int i;
232         for_each_online_cpu(i) {
233                 ondemand_powersave_bias_init_cpu(i);
234         }
235 }
236
237 /************************** sysfs interface ************************/
238
239 static ssize_t show_sampling_rate_min(struct kobject *kobj,
240                                       struct attribute *attr, char *buf)
241 {
242         return sprintf(buf, "%u\n", min_sampling_rate);
243 }
244
245 define_one_global_ro(sampling_rate_min);
246
247 /* cpufreq_ondemand Governor Tunables */
248 #define show_one(file_name, object)                                     \
249 static ssize_t show_##file_name                                         \
250 (struct kobject *kobj, struct attribute *attr, char *buf)              \
251 {                                                                       \
252         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
253 }
254 show_one(sampling_rate, sampling_rate);
255 show_one(io_is_busy, io_is_busy);
256 show_one(up_threshold, up_threshold);
257 show_one(sampling_down_factor, sampling_down_factor);
258 show_one(ignore_nice_load, ignore_nice);
259 show_one(powersave_bias, powersave_bias);
260
261 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
262                                    const char *buf, size_t count)
263 {
264         unsigned int input;
265         int ret;
266         ret = sscanf(buf, "%u", &input);
267         if (ret != 1)
268                 return -EINVAL;
269         dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
270         return count;
271 }
272
273 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
274                                    const char *buf, size_t count)
275 {
276         unsigned int input;
277         int ret;
278
279         ret = sscanf(buf, "%u", &input);
280         if (ret != 1)
281                 return -EINVAL;
282         dbs_tuners_ins.io_is_busy = !!input;
283         return count;
284 }
285
286 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
287                                   const char *buf, size_t count)
288 {
289         unsigned int input;
290         int ret;
291         ret = sscanf(buf, "%u", &input);
292
293         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
294                         input < MIN_FREQUENCY_UP_THRESHOLD) {
295                 return -EINVAL;
296         }
297         dbs_tuners_ins.up_threshold = input;
298         return count;
299 }
300
301 static ssize_t store_sampling_down_factor(struct kobject *a,
302                         struct attribute *b, const char *buf, size_t count)
303 {
304         unsigned int input, j;
305         int ret;
306         ret = sscanf(buf, "%u", &input);
307
308         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
309                 return -EINVAL;
310         dbs_tuners_ins.sampling_down_factor = input;
311
312         /* Reset down sampling multiplier in case it was active */
313         for_each_online_cpu(j) {
314                 struct cpu_dbs_info_s *dbs_info;
315                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
316                 dbs_info->rate_mult = 1;
317         }
318         return count;
319 }
320
321 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
322                                       const char *buf, size_t count)
323 {
324         unsigned int input;
325         int ret;
326
327         unsigned int j;
328
329         ret = sscanf(buf, "%u", &input);
330         if (ret != 1)
331                 return -EINVAL;
332
333         if (input > 1)
334                 input = 1;
335
336         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
337                 return count;
338         }
339         dbs_tuners_ins.ignore_nice = input;
340
341         /* we need to re-evaluate prev_cpu_idle */
342         for_each_online_cpu(j) {
343                 struct cpu_dbs_info_s *dbs_info;
344                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
345                 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
346                                                 &dbs_info->prev_cpu_wall);
347                 if (dbs_tuners_ins.ignore_nice)
348                         dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
349
350         }
351         return count;
352 }
353
354 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
355                                     const char *buf, size_t count)
356 {
357         unsigned int input;
358         int ret;
359         ret = sscanf(buf, "%u", &input);
360
361         if (ret != 1)
362                 return -EINVAL;
363
364         if (input > 1000)
365                 input = 1000;
366
367         dbs_tuners_ins.powersave_bias = input;
368         ondemand_powersave_bias_init();
369         return count;
370 }
371
372 define_one_global_rw(sampling_rate);
373 define_one_global_rw(io_is_busy);
374 define_one_global_rw(up_threshold);
375 define_one_global_rw(sampling_down_factor);
376 define_one_global_rw(ignore_nice_load);
377 define_one_global_rw(powersave_bias);
378
379 static struct attribute *dbs_attributes[] = {
380         &sampling_rate_min.attr,
381         &sampling_rate.attr,
382         &up_threshold.attr,
383         &sampling_down_factor.attr,
384         &ignore_nice_load.attr,
385         &powersave_bias.attr,
386         &io_is_busy.attr,
387         NULL
388 };
389
390 static struct attribute_group dbs_attr_group = {
391         .attrs = dbs_attributes,
392         .name = "ondemand",
393 };
394
395 /************************** sysfs end ************************/
396
397 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
398 {
399         if (dbs_tuners_ins.powersave_bias)
400                 freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
401         else if (p->cur == p->max)
402                 return;
403
404         __cpufreq_driver_target(p, freq, dbs_tuners_ins.powersave_bias ?
405                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
406 }
407
408 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
409 {
410         unsigned int max_load_freq;
411
412         struct cpufreq_policy *policy;
413         unsigned int j;
414
415         this_dbs_info->freq_lo = 0;
416         policy = this_dbs_info->cur_policy;
417
418         /*
419          * Every sampling_rate, we check, if current idle time is less
420          * than 20% (default), then we try to increase frequency
421          * Every sampling_rate, we look for a the lowest
422          * frequency which can sustain the load while keeping idle time over
423          * 30%. If such a frequency exist, we try to decrease to this frequency.
424          *
425          * Any frequency increase takes it to the maximum frequency.
426          * Frequency reduction happens at minimum steps of
427          * 5% (default) of current frequency
428          */
429
430         /* Get Absolute Load - in terms of freq */
431         max_load_freq = 0;
432
433         for_each_cpu(j, policy->cpus) {
434                 struct cpu_dbs_info_s *j_dbs_info;
435                 cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
436                 unsigned int idle_time, wall_time, iowait_time;
437                 unsigned int load, load_freq;
438                 int freq_avg;
439
440                 j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
441
442                 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
443                 cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
444
445                 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
446                                 j_dbs_info->prev_cpu_wall);
447                 j_dbs_info->prev_cpu_wall = cur_wall_time;
448
449                 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
450                                 j_dbs_info->prev_cpu_idle);
451                 j_dbs_info->prev_cpu_idle = cur_idle_time;
452
453                 iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
454                                 j_dbs_info->prev_cpu_iowait);
455                 j_dbs_info->prev_cpu_iowait = cur_iowait_time;
456
457                 if (dbs_tuners_ins.ignore_nice) {
458                         cputime64_t cur_nice;
459                         unsigned long cur_nice_jiffies;
460
461                         cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
462                                          j_dbs_info->prev_cpu_nice);
463                         /*
464                          * Assumption: nice time between sampling periods will
465                          * be less than 2^32 jiffies for 32 bit sys
466                          */
467                         cur_nice_jiffies = (unsigned long)
468                                         cputime64_to_jiffies64(cur_nice);
469
470                         j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
471                         idle_time += jiffies_to_usecs(cur_nice_jiffies);
472                 }
473
474                 /*
475                  * For the purpose of ondemand, waiting for disk IO is an
476                  * indication that you're performance critical, and not that
477                  * the system is actually idle. So subtract the iowait time
478                  * from the cpu idle time.
479                  */
480
481                 if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
482                         idle_time -= iowait_time;
483
484                 if (unlikely(!wall_time || wall_time < idle_time))
485                         continue;
486
487                 load = 100 * (wall_time - idle_time) / wall_time;
488
489                 freq_avg = __cpufreq_driver_getavg(policy, j);
490                 if (freq_avg <= 0)
491                         freq_avg = policy->cur;
492
493                 load_freq = load * freq_avg;
494                 if (load_freq > max_load_freq)
495                         max_load_freq = load_freq;
496         }
497
498         /* Check for frequency increase */
499         if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
500                 /* If switching to max speed, apply sampling_down_factor */
501                 if (policy->cur < policy->max)
502                         this_dbs_info->rate_mult =
503                                 dbs_tuners_ins.sampling_down_factor;
504                 dbs_freq_increase(policy, policy->max);
505                 return;
506         }
507
508         /* Check for frequency decrease */
509         /* if we cannot reduce the frequency anymore, break out early */
510         if (policy->cur == policy->min)
511                 return;
512
513         /*
514          * The optimal frequency is the frequency that is the lowest that
515          * can support the current CPU usage without triggering the up
516          * policy. To be safe, we focus 10 points under the threshold.
517          */
518         if (max_load_freq <
519             (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
520              policy->cur) {
521                 unsigned int freq_next;
522                 freq_next = max_load_freq /
523                                 (dbs_tuners_ins.up_threshold -
524                                  dbs_tuners_ins.down_differential);
525
526                 /* No longer fully busy, reset rate_mult */
527                 this_dbs_info->rate_mult = 1;
528
529                 if (freq_next < policy->min)
530                         freq_next = policy->min;
531
532                 if (!dbs_tuners_ins.powersave_bias) {
533                         __cpufreq_driver_target(policy, freq_next,
534                                         CPUFREQ_RELATION_L);
535                 } else {
536                         int freq = powersave_bias_target(policy, freq_next,
537                                         CPUFREQ_RELATION_L);
538                         __cpufreq_driver_target(policy, freq,
539                                 CPUFREQ_RELATION_L);
540                 }
541         }
542 }
543
544 static void do_dbs_timer(struct work_struct *work)
545 {
546         struct cpu_dbs_info_s *dbs_info =
547                 container_of(work, struct cpu_dbs_info_s, work.work);
548         unsigned int cpu = dbs_info->cpu;
549         int sample_type = dbs_info->sample_type;
550
551         int delay;
552
553         mutex_lock(&dbs_info->timer_mutex);
554
555         /* Common NORMAL_SAMPLE setup */
556         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
557         if (!dbs_tuners_ins.powersave_bias ||
558             sample_type == DBS_NORMAL_SAMPLE) {
559                 dbs_check_cpu(dbs_info);
560                 if (dbs_info->freq_lo) {
561                         /* Setup timer for SUB_SAMPLE */
562                         dbs_info->sample_type = DBS_SUB_SAMPLE;
563                         delay = dbs_info->freq_hi_jiffies;
564                 } else {
565                         /* We want all CPUs to do sampling nearly on
566                          * same jiffy
567                          */
568                         delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
569                                 * dbs_info->rate_mult);
570
571                         if (num_online_cpus() > 1)
572                                 delay -= jiffies % delay;
573                 }
574         } else {
575                 __cpufreq_driver_target(dbs_info->cur_policy,
576                         dbs_info->freq_lo, CPUFREQ_RELATION_H);
577                 delay = dbs_info->freq_lo_jiffies;
578         }
579         schedule_delayed_work_on(cpu, &dbs_info->work, delay);
580         mutex_unlock(&dbs_info->timer_mutex);
581 }
582
583 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
584 {
585         /* We want all CPUs to do sampling nearly on same jiffy */
586         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
587
588         if (num_online_cpus() > 1)
589                 delay -= jiffies % delay;
590
591         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
592         INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
593         schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work, delay);
594 }
595
596 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
597 {
598         cancel_delayed_work_sync(&dbs_info->work);
599 }
600
601 /*
602  * Not all CPUs want IO time to be accounted as busy; this dependson how
603  * efficient idling at a higher frequency/voltage is.
604  * Pavel Machek says this is not so for various generations of AMD and old
605  * Intel systems.
606  * Mike Chan (androidlcom) calis this is also not true for ARM.
607  * Because of this, whitelist specific known (series) of CPUs by default, and
608  * leave all others up to the user.
609  */
610 static int should_io_be_busy(void)
611 {
612 #if defined(CONFIG_X86)
613         /*
614          * For Intel, Core 2 (model 15) andl later have an efficient idle.
615          */
616         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
617             boot_cpu_data.x86 == 6 &&
618             boot_cpu_data.x86_model >= 15)
619                 return 1;
620 #endif
621         return 0;
622 }
623
624 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
625                                    unsigned int event)
626 {
627         unsigned int cpu = policy->cpu;
628         struct cpu_dbs_info_s *this_dbs_info;
629         unsigned int j;
630         int rc;
631
632         this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
633
634         switch (event) {
635         case CPUFREQ_GOV_START:
636                 if ((!cpu_online(cpu)) || (!policy->cur))
637                         return -EINVAL;
638
639                 mutex_lock(&dbs_mutex);
640
641                 dbs_enable++;
642                 for_each_cpu(j, policy->cpus) {
643                         struct cpu_dbs_info_s *j_dbs_info;
644                         j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
645                         j_dbs_info->cur_policy = policy;
646
647                         j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
648                                                 &j_dbs_info->prev_cpu_wall);
649                         if (dbs_tuners_ins.ignore_nice) {
650                                 j_dbs_info->prev_cpu_nice =
651                                                 kstat_cpu(j).cpustat.nice;
652                         }
653                 }
654                 this_dbs_info->cpu = cpu;
655                 this_dbs_info->rate_mult = 1;
656                 ondemand_powersave_bias_init_cpu(cpu);
657                 /*
658                  * Start the timerschedule work, when this governor
659                  * is used for first time
660                  */
661                 if (dbs_enable == 1) {
662                         unsigned int latency;
663
664                         rc = sysfs_create_group(cpufreq_global_kobject,
665                                                 &dbs_attr_group);
666                         if (rc) {
667                                 mutex_unlock(&dbs_mutex);
668                                 return rc;
669                         }
670
671                         /* policy latency is in nS. Convert it to uS first */
672                         latency = policy->cpuinfo.transition_latency / 1000;
673                         if (latency == 0)
674                                 latency = 1;
675                         /* Bring kernel and HW constraints together */
676                         min_sampling_rate = max(min_sampling_rate,
677                                         MIN_LATENCY_MULTIPLIER * latency);
678                         dbs_tuners_ins.sampling_rate =
679                                 max(min_sampling_rate,
680                                     latency * LATENCY_MULTIPLIER);
681                         dbs_tuners_ins.io_is_busy = should_io_be_busy();
682                 }
683                 mutex_unlock(&dbs_mutex);
684
685                 mutex_init(&this_dbs_info->timer_mutex);
686                 dbs_timer_init(this_dbs_info);
687                 break;
688
689         case CPUFREQ_GOV_STOP:
690                 dbs_timer_exit(this_dbs_info);
691
692                 mutex_lock(&dbs_mutex);
693                 mutex_destroy(&this_dbs_info->timer_mutex);
694                 dbs_enable--;
695                 mutex_unlock(&dbs_mutex);
696                 if (!dbs_enable)
697                         sysfs_remove_group(cpufreq_global_kobject,
698                                            &dbs_attr_group);
699
700                 break;
701
702         case CPUFREQ_GOV_LIMITS:
703                 mutex_lock(&this_dbs_info->timer_mutex);
704                 if (policy->max < this_dbs_info->cur_policy->cur)
705                         __cpufreq_driver_target(this_dbs_info->cur_policy,
706                                 policy->max, CPUFREQ_RELATION_H);
707                 else if (policy->min > this_dbs_info->cur_policy->cur)
708                         __cpufreq_driver_target(this_dbs_info->cur_policy,
709                                 policy->min, CPUFREQ_RELATION_L);
710                 mutex_unlock(&this_dbs_info->timer_mutex);
711                 break;
712         }
713         return 0;
714 }
715
716 static int __init cpufreq_gov_dbs_init(void)
717 {
718         cputime64_t wall;
719         u64 idle_time;
720         int cpu = get_cpu();
721
722         idle_time = get_cpu_idle_time_us(cpu, &wall);
723         put_cpu();
724         if (idle_time != -1ULL) {
725                 /* Idle micro accounting is supported. Use finer thresholds */
726                 dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
727                 dbs_tuners_ins.down_differential =
728                                         MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
729                 /*
730                  * In nohz/micro accounting case we set the minimum frequency
731                  * not depending on HZ, but fixed (very low). The deferred
732                  * timer might skip some samples if idle/sleeping as needed.
733                 */
734                 min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
735         } else {
736                 /* For correct statistics, we need 10 ticks for each measure */
737                 min_sampling_rate =
738                         MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
739         }
740
741         return cpufreq_register_governor(&cpufreq_gov_ondemand);
742 }
743
744 static void __exit cpufreq_gov_dbs_exit(void)
745 {
746         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
747 }
748
749
750 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
751 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
752 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
753         "Low Latency Frequency Transition capable processors");
754 MODULE_LICENSE("GPL");
755
756 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
757 fs_initcall(cpufreq_gov_dbs_init);
758 #else
759 module_init(cpufreq_gov_dbs_init);
760 #endif
761 module_exit(cpufreq_gov_dbs_exit);