[CPUFREQ] fix BUG on cpufreq policy init failure
[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 data in dbs_tuners_ins from concurrent changes on
103  * different CPUs. It protects dbs_enable in governor start/stop.
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 sampling_down_factor;
115         unsigned int powersave_bias;
116         unsigned int io_is_busy;
117 } dbs_tuners_ins = {
118         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
119         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
120         .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
121         .ignore_nice = 0,
122         .powersave_bias = 0,
123 };
124
125 static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
126                                                         cputime64_t *wall)
127 {
128         cputime64_t idle_time;
129         cputime64_t cur_wall_time;
130         cputime64_t busy_time;
131
132         cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
133         busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
134                         kstat_cpu(cpu).cpustat.system);
135
136         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
137         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
138         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
139         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
140
141         idle_time = cputime64_sub(cur_wall_time, busy_time);
142         if (wall)
143                 *wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
144
145         return (cputime64_t)jiffies_to_usecs(idle_time);
146 }
147
148 static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
149 {
150         u64 idle_time = get_cpu_idle_time_us(cpu, wall);
151
152         if (idle_time == -1ULL)
153                 return get_cpu_idle_time_jiffy(cpu, wall);
154
155         return idle_time;
156 }
157
158 static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
159 {
160         u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
161
162         if (iowait_time == -1ULL)
163                 return 0;
164
165         return iowait_time;
166 }
167
168 /*
169  * Find right freq to be set now with powersave_bias on.
170  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
171  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
172  */
173 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
174                                           unsigned int freq_next,
175                                           unsigned int relation)
176 {
177         unsigned int freq_req, freq_reduc, freq_avg;
178         unsigned int freq_hi, freq_lo;
179         unsigned int index = 0;
180         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
181         struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
182                                                    policy->cpu);
183
184         if (!dbs_info->freq_table) {
185                 dbs_info->freq_lo = 0;
186                 dbs_info->freq_lo_jiffies = 0;
187                 return freq_next;
188         }
189
190         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
191                         relation, &index);
192         freq_req = dbs_info->freq_table[index].frequency;
193         freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
194         freq_avg = freq_req - freq_reduc;
195
196         /* Find freq bounds for freq_avg in freq_table */
197         index = 0;
198         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
199                         CPUFREQ_RELATION_H, &index);
200         freq_lo = dbs_info->freq_table[index].frequency;
201         index = 0;
202         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
203                         CPUFREQ_RELATION_L, &index);
204         freq_hi = dbs_info->freq_table[index].frequency;
205
206         /* Find out how long we have to be in hi and lo freqs */
207         if (freq_hi == freq_lo) {
208                 dbs_info->freq_lo = 0;
209                 dbs_info->freq_lo_jiffies = 0;
210                 return freq_lo;
211         }
212         jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
213         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
214         jiffies_hi += ((freq_hi - freq_lo) / 2);
215         jiffies_hi /= (freq_hi - freq_lo);
216         jiffies_lo = jiffies_total - jiffies_hi;
217         dbs_info->freq_lo = freq_lo;
218         dbs_info->freq_lo_jiffies = jiffies_lo;
219         dbs_info->freq_hi_jiffies = jiffies_hi;
220         return freq_hi;
221 }
222
223 static void ondemand_powersave_bias_init_cpu(int cpu)
224 {
225         struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
226         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
227         dbs_info->freq_lo = 0;
228 }
229
230 static void ondemand_powersave_bias_init(void)
231 {
232         int i;
233         for_each_online_cpu(i) {
234                 ondemand_powersave_bias_init_cpu(i);
235         }
236 }
237
238 /************************** sysfs interface ************************/
239
240 static ssize_t show_sampling_rate_max(struct kobject *kobj,
241                                       struct attribute *attr, char *buf)
242 {
243         printk_once(KERN_INFO "CPUFREQ: ondemand sampling_rate_max "
244                "sysfs file is deprecated - used by: %s\n", current->comm);
245         return sprintf(buf, "%u\n", -1U);
246 }
247
248 static ssize_t show_sampling_rate_min(struct kobject *kobj,
249                                       struct attribute *attr, char *buf)
250 {
251         return sprintf(buf, "%u\n", min_sampling_rate);
252 }
253
254 define_one_global_ro(sampling_rate_max);
255 define_one_global_ro(sampling_rate_min);
256
257 /* cpufreq_ondemand Governor Tunables */
258 #define show_one(file_name, object)                                     \
259 static ssize_t show_##file_name                                         \
260 (struct kobject *kobj, struct attribute *attr, char *buf)              \
261 {                                                                       \
262         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
263 }
264 show_one(sampling_rate, sampling_rate);
265 show_one(io_is_busy, io_is_busy);
266 show_one(up_threshold, up_threshold);
267 show_one(sampling_down_factor, sampling_down_factor);
268 show_one(ignore_nice_load, ignore_nice);
269 show_one(powersave_bias, powersave_bias);
270
271 /*** delete after deprecation time ***/
272
273 #define DEPRECATION_MSG(file_name)                                      \
274         printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "       \
275                     "interface is deprecated - " #file_name "\n");
276
277 #define show_one_old(file_name)                                         \
278 static ssize_t show_##file_name##_old                                   \
279 (struct cpufreq_policy *unused, char *buf)                              \
280 {                                                                       \
281         printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "       \
282                     "interface is deprecated - " #file_name "\n");      \
283         return show_##file_name(NULL, NULL, buf);                       \
284 }
285 show_one_old(sampling_rate);
286 show_one_old(up_threshold);
287 show_one_old(ignore_nice_load);
288 show_one_old(powersave_bias);
289 show_one_old(sampling_rate_min);
290 show_one_old(sampling_rate_max);
291
292 cpufreq_freq_attr_ro_old(sampling_rate_min);
293 cpufreq_freq_attr_ro_old(sampling_rate_max);
294
295 /*** delete after deprecation time ***/
296
297 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
298                                    const char *buf, size_t count)
299 {
300         unsigned int input;
301         int ret;
302         ret = sscanf(buf, "%u", &input);
303         if (ret != 1)
304                 return -EINVAL;
305
306         mutex_lock(&dbs_mutex);
307         dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
308         mutex_unlock(&dbs_mutex);
309
310         return count;
311 }
312
313 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
314                                    const char *buf, size_t count)
315 {
316         unsigned int input;
317         int ret;
318
319         ret = sscanf(buf, "%u", &input);
320         if (ret != 1)
321                 return -EINVAL;
322
323         mutex_lock(&dbs_mutex);
324         dbs_tuners_ins.io_is_busy = !!input;
325         mutex_unlock(&dbs_mutex);
326
327         return count;
328 }
329
330 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
331                                   const char *buf, size_t count)
332 {
333         unsigned int input;
334         int ret;
335         ret = sscanf(buf, "%u", &input);
336
337         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
338                         input < MIN_FREQUENCY_UP_THRESHOLD) {
339                 return -EINVAL;
340         }
341
342         mutex_lock(&dbs_mutex);
343         dbs_tuners_ins.up_threshold = input;
344         mutex_unlock(&dbs_mutex);
345
346         return count;
347 }
348
349 static ssize_t store_sampling_down_factor(struct kobject *a,
350                         struct attribute *b, const char *buf, size_t count)
351 {
352         unsigned int input, j;
353         int ret;
354         ret = sscanf(buf, "%u", &input);
355
356         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
357                 return -EINVAL;
358         mutex_lock(&dbs_mutex);
359         dbs_tuners_ins.sampling_down_factor = input;
360
361         /* Reset down sampling multiplier in case it was active */
362         for_each_online_cpu(j) {
363                 struct cpu_dbs_info_s *dbs_info;
364                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
365                 dbs_info->rate_mult = 1;
366         }
367         mutex_unlock(&dbs_mutex);
368
369         return count;
370 }
371
372 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
373                                       const char *buf, size_t count)
374 {
375         unsigned int input;
376         int ret;
377
378         unsigned int j;
379
380         ret = sscanf(buf, "%u", &input);
381         if (ret != 1)
382                 return -EINVAL;
383
384         if (input > 1)
385                 input = 1;
386
387         mutex_lock(&dbs_mutex);
388         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
389                 mutex_unlock(&dbs_mutex);
390                 return count;
391         }
392         dbs_tuners_ins.ignore_nice = input;
393
394         /* we need to re-evaluate prev_cpu_idle */
395         for_each_online_cpu(j) {
396                 struct cpu_dbs_info_s *dbs_info;
397                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
398                 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
399                                                 &dbs_info->prev_cpu_wall);
400                 if (dbs_tuners_ins.ignore_nice)
401                         dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
402
403         }
404         mutex_unlock(&dbs_mutex);
405
406         return count;
407 }
408
409 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
410                                     const char *buf, size_t count)
411 {
412         unsigned int input;
413         int ret;
414         ret = sscanf(buf, "%u", &input);
415
416         if (ret != 1)
417                 return -EINVAL;
418
419         if (input > 1000)
420                 input = 1000;
421
422         mutex_lock(&dbs_mutex);
423         dbs_tuners_ins.powersave_bias = input;
424         ondemand_powersave_bias_init();
425         mutex_unlock(&dbs_mutex);
426
427         return count;
428 }
429
430 define_one_global_rw(sampling_rate);
431 define_one_global_rw(io_is_busy);
432 define_one_global_rw(up_threshold);
433 define_one_global_rw(sampling_down_factor);
434 define_one_global_rw(ignore_nice_load);
435 define_one_global_rw(powersave_bias);
436
437 static struct attribute *dbs_attributes[] = {
438         &sampling_rate_max.attr,
439         &sampling_rate_min.attr,
440         &sampling_rate.attr,
441         &up_threshold.attr,
442         &sampling_down_factor.attr,
443         &ignore_nice_load.attr,
444         &powersave_bias.attr,
445         &io_is_busy.attr,
446         NULL
447 };
448
449 static struct attribute_group dbs_attr_group = {
450         .attrs = dbs_attributes,
451         .name = "ondemand",
452 };
453
454 /*** delete after deprecation time ***/
455
456 #define write_one_old(file_name)                                        \
457 static ssize_t store_##file_name##_old                                  \
458 (struct cpufreq_policy *unused, const char *buf, size_t count)          \
459 {                                                                       \
460        printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "        \
461                    "interface is deprecated - " #file_name "\n");       \
462        return store_##file_name(NULL, NULL, buf, count);                \
463 }
464 write_one_old(sampling_rate);
465 write_one_old(up_threshold);
466 write_one_old(ignore_nice_load);
467 write_one_old(powersave_bias);
468
469 cpufreq_freq_attr_rw_old(sampling_rate);
470 cpufreq_freq_attr_rw_old(up_threshold);
471 cpufreq_freq_attr_rw_old(ignore_nice_load);
472 cpufreq_freq_attr_rw_old(powersave_bias);
473
474 static struct attribute *dbs_attributes_old[] = {
475        &sampling_rate_max_old.attr,
476        &sampling_rate_min_old.attr,
477        &sampling_rate_old.attr,
478        &up_threshold_old.attr,
479        &ignore_nice_load_old.attr,
480        &powersave_bias_old.attr,
481        NULL
482 };
483
484 static struct attribute_group dbs_attr_group_old = {
485        .attrs = dbs_attributes_old,
486        .name = "ondemand",
487 };
488
489 /*** delete after deprecation time ***/
490
491 /************************** sysfs end ************************/
492
493 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
494 {
495         if (dbs_tuners_ins.powersave_bias)
496                 freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
497         else if (p->cur == p->max)
498                 return;
499
500         __cpufreq_driver_target(p, freq, dbs_tuners_ins.powersave_bias ?
501                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
502 }
503
504 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
505 {
506         unsigned int max_load_freq;
507
508         struct cpufreq_policy *policy;
509         unsigned int j;
510
511         this_dbs_info->freq_lo = 0;
512         policy = this_dbs_info->cur_policy;
513
514         /*
515          * Every sampling_rate, we check, if current idle time is less
516          * than 20% (default), then we try to increase frequency
517          * Every sampling_rate, we look for a the lowest
518          * frequency which can sustain the load while keeping idle time over
519          * 30%. If such a frequency exist, we try to decrease to this frequency.
520          *
521          * Any frequency increase takes it to the maximum frequency.
522          * Frequency reduction happens at minimum steps of
523          * 5% (default) of current frequency
524          */
525
526         /* Get Absolute Load - in terms of freq */
527         max_load_freq = 0;
528
529         for_each_cpu(j, policy->cpus) {
530                 struct cpu_dbs_info_s *j_dbs_info;
531                 cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
532                 unsigned int idle_time, wall_time, iowait_time;
533                 unsigned int load, load_freq;
534                 int freq_avg;
535
536                 j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
537
538                 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
539                 cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
540
541                 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
542                                 j_dbs_info->prev_cpu_wall);
543                 j_dbs_info->prev_cpu_wall = cur_wall_time;
544
545                 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
546                                 j_dbs_info->prev_cpu_idle);
547                 j_dbs_info->prev_cpu_idle = cur_idle_time;
548
549                 iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
550                                 j_dbs_info->prev_cpu_iowait);
551                 j_dbs_info->prev_cpu_iowait = cur_iowait_time;
552
553                 if (dbs_tuners_ins.ignore_nice) {
554                         cputime64_t cur_nice;
555                         unsigned long cur_nice_jiffies;
556
557                         cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
558                                          j_dbs_info->prev_cpu_nice);
559                         /*
560                          * Assumption: nice time between sampling periods will
561                          * be less than 2^32 jiffies for 32 bit sys
562                          */
563                         cur_nice_jiffies = (unsigned long)
564                                         cputime64_to_jiffies64(cur_nice);
565
566                         j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
567                         idle_time += jiffies_to_usecs(cur_nice_jiffies);
568                 }
569
570                 /*
571                  * For the purpose of ondemand, waiting for disk IO is an
572                  * indication that you're performance critical, and not that
573                  * the system is actually idle. So subtract the iowait time
574                  * from the cpu idle time.
575                  */
576
577                 if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
578                         idle_time -= iowait_time;
579
580                 if (unlikely(!wall_time || wall_time < idle_time))
581                         continue;
582
583                 load = 100 * (wall_time - idle_time) / wall_time;
584
585                 freq_avg = __cpufreq_driver_getavg(policy, j);
586                 if (freq_avg <= 0)
587                         freq_avg = policy->cur;
588
589                 load_freq = load * freq_avg;
590                 if (load_freq > max_load_freq)
591                         max_load_freq = load_freq;
592         }
593
594         /* Check for frequency increase */
595         if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
596                 /* If switching to max speed, apply sampling_down_factor */
597                 if (policy->cur < policy->max)
598                         this_dbs_info->rate_mult =
599                                 dbs_tuners_ins.sampling_down_factor;
600                 dbs_freq_increase(policy, policy->max);
601                 return;
602         }
603
604         /* Check for frequency decrease */
605         /* if we cannot reduce the frequency anymore, break out early */
606         if (policy->cur == policy->min)
607                 return;
608
609         /*
610          * The optimal frequency is the frequency that is the lowest that
611          * can support the current CPU usage without triggering the up
612          * policy. To be safe, we focus 10 points under the threshold.
613          */
614         if (max_load_freq <
615             (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
616              policy->cur) {
617                 unsigned int freq_next;
618                 freq_next = max_load_freq /
619                                 (dbs_tuners_ins.up_threshold -
620                                  dbs_tuners_ins.down_differential);
621
622                 /* No longer fully busy, reset rate_mult */
623                 this_dbs_info->rate_mult = 1;
624
625                 if (freq_next < policy->min)
626                         freq_next = policy->min;
627
628                 if (!dbs_tuners_ins.powersave_bias) {
629                         __cpufreq_driver_target(policy, freq_next,
630                                         CPUFREQ_RELATION_L);
631                 } else {
632                         int freq = powersave_bias_target(policy, freq_next,
633                                         CPUFREQ_RELATION_L);
634                         __cpufreq_driver_target(policy, freq,
635                                 CPUFREQ_RELATION_L);
636                 }
637         }
638 }
639
640 static void do_dbs_timer(struct work_struct *work)
641 {
642         struct cpu_dbs_info_s *dbs_info =
643                 container_of(work, struct cpu_dbs_info_s, work.work);
644         unsigned int cpu = dbs_info->cpu;
645         int sample_type = dbs_info->sample_type;
646
647         /* We want all CPUs to do sampling nearly on same jiffy */
648         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
649                 * dbs_info->rate_mult);
650
651         if (num_online_cpus() > 1)
652                 delay -= jiffies % delay;
653
654         mutex_lock(&dbs_info->timer_mutex);
655
656         /* Common NORMAL_SAMPLE setup */
657         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
658         if (!dbs_tuners_ins.powersave_bias ||
659             sample_type == DBS_NORMAL_SAMPLE) {
660                 dbs_check_cpu(dbs_info);
661                 if (dbs_info->freq_lo) {
662                         /* Setup timer for SUB_SAMPLE */
663                         dbs_info->sample_type = DBS_SUB_SAMPLE;
664                         delay = dbs_info->freq_hi_jiffies;
665                 }
666         } else {
667                 __cpufreq_driver_target(dbs_info->cur_policy,
668                         dbs_info->freq_lo, CPUFREQ_RELATION_H);
669         }
670         queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
671         mutex_unlock(&dbs_info->timer_mutex);
672 }
673
674 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
675 {
676         /* We want all CPUs to do sampling nearly on same jiffy */
677         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
678
679         if (num_online_cpus() > 1)
680                 delay -= jiffies % delay;
681
682         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
683         INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
684         queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work,
685                 delay);
686 }
687
688 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
689 {
690         cancel_delayed_work_sync(&dbs_info->work);
691 }
692
693 /*
694  * Not all CPUs want IO time to be accounted as busy; this dependson how
695  * efficient idling at a higher frequency/voltage is.
696  * Pavel Machek says this is not so for various generations of AMD and old
697  * Intel systems.
698  * Mike Chan (androidlcom) calis this is also not true for ARM.
699  * Because of this, whitelist specific known (series) of CPUs by default, and
700  * leave all others up to the user.
701  */
702 static int should_io_be_busy(void)
703 {
704 #if defined(CONFIG_X86)
705         /*
706          * For Intel, Core 2 (model 15) andl later have an efficient idle.
707          */
708         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
709             boot_cpu_data.x86 == 6 &&
710             boot_cpu_data.x86_model >= 15)
711                 return 1;
712 #endif
713         return 0;
714 }
715
716 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
717                                    unsigned int event)
718 {
719         unsigned int cpu = policy->cpu;
720         struct cpu_dbs_info_s *this_dbs_info;
721         unsigned int j;
722         int rc;
723
724         this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
725
726         switch (event) {
727         case CPUFREQ_GOV_START:
728                 if ((!cpu_online(cpu)) || (!policy->cur))
729                         return -EINVAL;
730
731                 mutex_lock(&dbs_mutex);
732
733                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group_old);
734                 if (rc) {
735                         mutex_unlock(&dbs_mutex);
736                         return rc;
737                 }
738
739                 dbs_enable++;
740                 for_each_cpu(j, policy->cpus) {
741                         struct cpu_dbs_info_s *j_dbs_info;
742                         j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
743                         j_dbs_info->cur_policy = policy;
744
745                         j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
746                                                 &j_dbs_info->prev_cpu_wall);
747                         if (dbs_tuners_ins.ignore_nice) {
748                                 j_dbs_info->prev_cpu_nice =
749                                                 kstat_cpu(j).cpustat.nice;
750                         }
751                 }
752                 this_dbs_info->cpu = cpu;
753                 this_dbs_info->rate_mult = 1;
754                 ondemand_powersave_bias_init_cpu(cpu);
755                 /*
756                  * Start the timerschedule work, when this governor
757                  * is used for first time
758                  */
759                 if (dbs_enable == 1) {
760                         unsigned int latency;
761
762                         rc = sysfs_create_group(cpufreq_global_kobject,
763                                                 &dbs_attr_group);
764                         if (rc) {
765                                 mutex_unlock(&dbs_mutex);
766                                 return rc;
767                         }
768
769                         /* policy latency is in nS. Convert it to uS first */
770                         latency = policy->cpuinfo.transition_latency / 1000;
771                         if (latency == 0)
772                                 latency = 1;
773                         /* Bring kernel and HW constraints together */
774                         min_sampling_rate = max(min_sampling_rate,
775                                         MIN_LATENCY_MULTIPLIER * latency);
776                         dbs_tuners_ins.sampling_rate =
777                                 max(min_sampling_rate,
778                                     latency * LATENCY_MULTIPLIER);
779                         dbs_tuners_ins.io_is_busy = should_io_be_busy();
780                 }
781                 mutex_unlock(&dbs_mutex);
782
783                 mutex_init(&this_dbs_info->timer_mutex);
784                 dbs_timer_init(this_dbs_info);
785                 break;
786
787         case CPUFREQ_GOV_STOP:
788                 dbs_timer_exit(this_dbs_info);
789
790                 mutex_lock(&dbs_mutex);
791                 sysfs_remove_group(&policy->kobj, &dbs_attr_group_old);
792                 mutex_destroy(&this_dbs_info->timer_mutex);
793                 dbs_enable--;
794                 mutex_unlock(&dbs_mutex);
795                 if (!dbs_enable)
796                         sysfs_remove_group(cpufreq_global_kobject,
797                                            &dbs_attr_group);
798
799                 break;
800
801         case CPUFREQ_GOV_LIMITS:
802                 mutex_lock(&this_dbs_info->timer_mutex);
803                 if (policy->max < this_dbs_info->cur_policy->cur)
804                         __cpufreq_driver_target(this_dbs_info->cur_policy,
805                                 policy->max, CPUFREQ_RELATION_H);
806                 else if (policy->min > this_dbs_info->cur_policy->cur)
807                         __cpufreq_driver_target(this_dbs_info->cur_policy,
808                                 policy->min, CPUFREQ_RELATION_L);
809                 mutex_unlock(&this_dbs_info->timer_mutex);
810                 break;
811         }
812         return 0;
813 }
814
815 static int __init cpufreq_gov_dbs_init(void)
816 {
817         int err;
818         cputime64_t wall;
819         u64 idle_time;
820         int cpu = get_cpu();
821
822         idle_time = get_cpu_idle_time_us(cpu, &wall);
823         put_cpu();
824         if (idle_time != -1ULL) {
825                 /* Idle micro accounting is supported. Use finer thresholds */
826                 dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
827                 dbs_tuners_ins.down_differential =
828                                         MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
829                 /*
830                  * In no_hz/micro accounting case we set the minimum frequency
831                  * not depending on HZ, but fixed (very low). The deferred
832                  * timer might skip some samples if idle/sleeping as needed.
833                 */
834                 min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
835         } else {
836                 /* For correct statistics, we need 10 ticks for each measure */
837                 min_sampling_rate =
838                         MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
839         }
840
841         kondemand_wq = create_workqueue("kondemand");
842         if (!kondemand_wq) {
843                 printk(KERN_ERR "Creation of kondemand failed\n");
844                 return -EFAULT;
845         }
846         err = cpufreq_register_governor(&cpufreq_gov_ondemand);
847         if (err)
848                 destroy_workqueue(kondemand_wq);
849
850         return err;
851 }
852
853 static void __exit cpufreq_gov_dbs_exit(void)
854 {
855         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
856         destroy_workqueue(kondemand_wq);
857 }
858
859
860 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
861 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
862 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
863         "Low Latency Frequency Transition capable processors");
864 MODULE_LICENSE("GPL");
865
866 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
867 fs_initcall(cpufreq_gov_dbs_init);
868 #else
869 module_init(cpufreq_gov_dbs_init);
870 #endif
871 module_exit(cpufreq_gov_dbs_exit);