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1/*
2 * drivers/cpufreq/cpufreq_conservative.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 * (C) 2009 Alexander Clouter <alex@digriz.org.uk>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/init.h>
17#include <linux/cpufreq.h>
18#include <linux/cpu.h>
19#include <linux/jiffies.h>
20#include <linux/kernel_stat.h>
21#include <linux/mutex.h>
22#include <linux/hrtimer.h>
23#include <linux/tick.h>
24#include <linux/ktime.h>
25#include <linux/sched.h>
26
27/*
28 * dbs is used in this file as a shortform for demandbased switching
29 * It helps to keep variable names smaller, simpler
30 */
31
32#define DEF_FREQUENCY_UP_THRESHOLD (80)
33#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
34
35/*
36 * The polling frequency of this governor depends on the capability of
37 * the processor. Default polling frequency is 1000 times the transition
38 * latency of the processor. The governor will work on any processor with
39 * transition latency <= 10mS, using appropriate sampling
40 * rate.
41 * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
42 * this governor will not work.
43 * All times here are in uS.
44 */
45#define MIN_SAMPLING_RATE_RATIO (2)
46
47static unsigned int min_sampling_rate;
48
49#define LATENCY_MULTIPLIER (1000)
50#define MIN_LATENCY_MULTIPLIER (100)
51#define DEF_SAMPLING_DOWN_FACTOR (1)
52#define MAX_SAMPLING_DOWN_FACTOR (10)
53#define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000)
54
55static void do_dbs_timer(struct work_struct *work);
56
57struct cpu_dbs_info_s {
58 cputime64_t prev_cpu_idle;
59 cputime64_t prev_cpu_wall;
60 cputime64_t prev_cpu_nice;
61 struct cpufreq_policy *cur_policy;
62 struct delayed_work work;
63 unsigned int down_skip;
64 unsigned int requested_freq;
65 int cpu;
66 unsigned int enable:1;
67 /*
68 * percpu mutex that serializes governor limit change with
69 * do_dbs_timer invocation. We do not want do_dbs_timer to run
70 * when user is changing the governor or limits.
71 */
72 struct mutex timer_mutex;
73};
74static DEFINE_PER_CPU(struct cpu_dbs_info_s, cs_cpu_dbs_info);
75
76static unsigned int dbs_enable; /* number of CPUs using this policy */
77
78/*
79 * dbs_mutex protects dbs_enable in governor start/stop.
80 */
81static DEFINE_MUTEX(dbs_mutex);
82
83static struct dbs_tuners {
84 unsigned int sampling_rate;
85 unsigned int sampling_down_factor;
86 unsigned int up_threshold;
87 unsigned int down_threshold;
88 unsigned int ignore_nice;
89 unsigned int freq_step;
90} dbs_tuners_ins = {
91 .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
92 .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
93 .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
94 .ignore_nice = 0,
95 .freq_step = 5,
96};
97
98static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
99 cputime64_t *wall)
100{
101 cputime64_t idle_time;
102 cputime64_t cur_wall_time;
103 cputime64_t busy_time;
104
105 cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
106 busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
107 kstat_cpu(cpu).cpustat.system);
108
109 busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
110 busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
111 busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
112 busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
113
114 idle_time = cputime64_sub(cur_wall_time, busy_time);
115 if (wall)
116 *wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
117
118 return (cputime64_t)jiffies_to_usecs(idle_time);
119}
120
121static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
122{
123 u64 idle_time = get_cpu_idle_time_us(cpu, wall);
124
125 if (idle_time == -1ULL)
126 return get_cpu_idle_time_jiffy(cpu, wall);
127
128 return idle_time;
129}
130
131/* keep track of frequency transitions */
132static int
133dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
134 void *data)
135{
136 struct cpufreq_freqs *freq = data;
137 struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cs_cpu_dbs_info,
138 freq->cpu);
139
140 struct cpufreq_policy *policy;
141
142 if (!this_dbs_info->enable)
143 return 0;
144
145 policy = this_dbs_info->cur_policy;
146
147 /*
148 * we only care if our internally tracked freq moves outside
149 * the 'valid' ranges of freqency available to us otherwise
150 * we do not change it
151 */
152 if (this_dbs_info->requested_freq > policy->max
153 || this_dbs_info->requested_freq < policy->min)
154 this_dbs_info->requested_freq = freq->new;
155
156 return 0;
157}
158
159static struct notifier_block dbs_cpufreq_notifier_block = {
160 .notifier_call = dbs_cpufreq_notifier
161};
162
163/************************** sysfs interface ************************/
164static ssize_t show_sampling_rate_min(struct kobject *kobj,
165 struct attribute *attr, char *buf)
166{
167 return sprintf(buf, "%u\n", min_sampling_rate);
168}
169
170define_one_global_ro(sampling_rate_min);
171
172/* cpufreq_conservative Governor Tunables */
173#define show_one(file_name, object) \
174static ssize_t show_##file_name \
175(struct kobject *kobj, struct attribute *attr, char *buf) \
176{ \
177 return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
178}
179show_one(sampling_rate, sampling_rate);
180show_one(sampling_down_factor, sampling_down_factor);
181show_one(up_threshold, up_threshold);
182show_one(down_threshold, down_threshold);
183show_one(ignore_nice_load, ignore_nice);
184show_one(freq_step, freq_step);
185
186static ssize_t store_sampling_down_factor(struct kobject *a,
187 struct attribute *b,
188 const char *buf, size_t count)
189{
190 unsigned int input;
191 int ret;
192 ret = sscanf(buf, "%u", &input);
193
194 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
195 return -EINVAL;
196
197 dbs_tuners_ins.sampling_down_factor = input;
198 return count;
199}
200
201static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
202 const char *buf, size_t count)
203{
204 unsigned int input;
205 int ret;
206 ret = sscanf(buf, "%u", &input);
207
208 if (ret != 1)
209 return -EINVAL;
210
211 dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
212 return count;
213}
214
215static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
216 const char *buf, size_t count)
217{
218 unsigned int input;
219 int ret;
220 ret = sscanf(buf, "%u", &input);
221
222 if (ret != 1 || input > 100 ||
223 input <= dbs_tuners_ins.down_threshold)
224 return -EINVAL;
225
226 dbs_tuners_ins.up_threshold = input;
227 return count;
228}
229
230static ssize_t store_down_threshold(struct kobject *a, struct attribute *b,
231 const char *buf, size_t count)
232{
233 unsigned int input;
234 int ret;
235 ret = sscanf(buf, "%u", &input);
236
237 /* cannot be lower than 11 otherwise freq will not fall */
238 if (ret != 1 || input < 11 || input > 100 ||
239 input >= dbs_tuners_ins.up_threshold)
240 return -EINVAL;
241
242 dbs_tuners_ins.down_threshold = input;
243 return count;
244}
245
246static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
247 const char *buf, size_t count)
248{
249 unsigned int input;
250 int ret;
251
252 unsigned int j;
253
254 ret = sscanf(buf, "%u", &input);
255 if (ret != 1)
256 return -EINVAL;
257
258 if (input > 1)
259 input = 1;
260
261 if (input == dbs_tuners_ins.ignore_nice) /* nothing to do */
262 return count;
263
264 dbs_tuners_ins.ignore_nice = input;
265
266 /* we need to re-evaluate prev_cpu_idle */
267 for_each_online_cpu(j) {
268 struct cpu_dbs_info_s *dbs_info;
269 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
270 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
271 &dbs_info->prev_cpu_wall);
272 if (dbs_tuners_ins.ignore_nice)
273 dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
274 }
275 return count;
276}
277
278static ssize_t store_freq_step(struct kobject *a, struct attribute *b,
279 const char *buf, size_t count)
280{
281 unsigned int input;
282 int ret;
283 ret = sscanf(buf, "%u", &input);
284
285 if (ret != 1)
286 return -EINVAL;
287
288 if (input > 100)
289 input = 100;
290
291 /* no need to test here if freq_step is zero as the user might actually
292 * want this, they would be crazy though :) */
293 dbs_tuners_ins.freq_step = input;
294 return count;
295}
296
297define_one_global_rw(sampling_rate);
298define_one_global_rw(sampling_down_factor);
299define_one_global_rw(up_threshold);
300define_one_global_rw(down_threshold);
301define_one_global_rw(ignore_nice_load);
302define_one_global_rw(freq_step);
303
304static struct attribute *dbs_attributes[] = {
305 &sampling_rate_min.attr,
306 &sampling_rate.attr,
307 &sampling_down_factor.attr,
308 &up_threshold.attr,
309 &down_threshold.attr,
310 &ignore_nice_load.attr,
311 &freq_step.attr,
312 NULL
313};
314
315static struct attribute_group dbs_attr_group = {
316 .attrs = dbs_attributes,
317 .name = "conservative",
318};
319
320/************************** sysfs end ************************/
321
322static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
323{
324 unsigned int load = 0;
325 unsigned int max_load = 0;
326 unsigned int freq_target;
327
328 struct cpufreq_policy *policy;
329 unsigned int j;
330
331 policy = this_dbs_info->cur_policy;
332
333 /*
334 * Every sampling_rate, we check, if current idle time is less
335 * than 20% (default), then we try to increase frequency
336 * Every sampling_rate*sampling_down_factor, we check, if current
337 * idle time is more than 80%, then we try to decrease frequency
338 *
339 * Any frequency increase takes it to the maximum frequency.
340 * Frequency reduction happens at minimum steps of
341 * 5% (default) of maximum frequency
342 */
343
344 /* Get Absolute Load */
345 for_each_cpu(j, policy->cpus) {
346 struct cpu_dbs_info_s *j_dbs_info;
347 cputime64_t cur_wall_time, cur_idle_time;
348 unsigned int idle_time, wall_time;
349
350 j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
351
352 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
353
354 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
355 j_dbs_info->prev_cpu_wall);
356 j_dbs_info->prev_cpu_wall = cur_wall_time;
357
358 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
359 j_dbs_info->prev_cpu_idle);
360 j_dbs_info->prev_cpu_idle = cur_idle_time;
361
362 if (dbs_tuners_ins.ignore_nice) {
363 cputime64_t cur_nice;
364 unsigned long cur_nice_jiffies;
365
366 cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
367 j_dbs_info->prev_cpu_nice);
368 /*
369 * Assumption: nice time between sampling periods will
370 * be less than 2^32 jiffies for 32 bit sys
371 */
372 cur_nice_jiffies = (unsigned long)
373 cputime64_to_jiffies64(cur_nice);
374
375 j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
376 idle_time += jiffies_to_usecs(cur_nice_jiffies);
377 }
378
379 if (unlikely(!wall_time || wall_time < idle_time))
380 continue;
381
382 load = 100 * (wall_time - idle_time) / wall_time;
383
384 if (load > max_load)
385 max_load = load;
386 }
387
388 /*
389 * break out if we 'cannot' reduce the speed as the user might
390 * want freq_step to be zero
391 */
392 if (dbs_tuners_ins.freq_step == 0)
393 return;
394
395 /* Check for frequency increase */
396 if (max_load > dbs_tuners_ins.up_threshold) {
397 this_dbs_info->down_skip = 0;
398
399 /* if we are already at full speed then break out early */
400 if (this_dbs_info->requested_freq == policy->max)
401 return;
402
403 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
404
405 /* max freq cannot be less than 100. But who knows.... */
406 if (unlikely(freq_target == 0))
407 freq_target = 5;
408
409 this_dbs_info->requested_freq += freq_target;
410 if (this_dbs_info->requested_freq > policy->max)
411 this_dbs_info->requested_freq = policy->max;
412
413 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
414 CPUFREQ_RELATION_H);
415 return;
416 }
417
418 /*
419 * The optimal frequency is the frequency that is the lowest that
420 * can support the current CPU usage without triggering the up
421 * policy. To be safe, we focus 10 points under the threshold.
422 */
423 if (max_load < (dbs_tuners_ins.down_threshold - 10)) {
424 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
425
426 this_dbs_info->requested_freq -= freq_target;
427 if (this_dbs_info->requested_freq < policy->min)
428 this_dbs_info->requested_freq = policy->min;
429
430 /*
431 * if we cannot reduce the frequency anymore, break out early
432 */
433 if (policy->cur == policy->min)
434 return;
435
436 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
437 CPUFREQ_RELATION_H);
438 return;
439 }
440}
441
442static void do_dbs_timer(struct work_struct *work)
443{
444 struct cpu_dbs_info_s *dbs_info =
445 container_of(work, struct cpu_dbs_info_s, work.work);
446 unsigned int cpu = dbs_info->cpu;
447
448 /* We want all CPUs to do sampling nearly on same jiffy */
449 int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
450
451 delay -= jiffies % delay;
452
453 mutex_lock(&dbs_info->timer_mutex);
454
455 dbs_check_cpu(dbs_info);
456
457 schedule_delayed_work_on(cpu, &dbs_info->work, delay);
458 mutex_unlock(&dbs_info->timer_mutex);
459}
460
461static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
462{
463 /* We want all CPUs to do sampling nearly on same jiffy */
464 int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
465 delay -= jiffies % delay;
466
467 dbs_info->enable = 1;
468 INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
469 schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work, delay);
470}
471
472static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
473{
474 dbs_info->enable = 0;
475 cancel_delayed_work_sync(&dbs_info->work);
476}
477
478static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
479 unsigned int event)
480{
481 unsigned int cpu = policy->cpu;
482 struct cpu_dbs_info_s *this_dbs_info;
483 unsigned int j;
484 int rc;
485
486 this_dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
487
488 switch (event) {
489 case CPUFREQ_GOV_START:
490 if ((!cpu_online(cpu)) || (!policy->cur))
491 return -EINVAL;
492
493 mutex_lock(&dbs_mutex);
494
495 for_each_cpu(j, policy->cpus) {
496 struct cpu_dbs_info_s *j_dbs_info;
497 j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
498 j_dbs_info->cur_policy = policy;
499
500 j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
501 &j_dbs_info->prev_cpu_wall);
502 if (dbs_tuners_ins.ignore_nice) {
503 j_dbs_info->prev_cpu_nice =
504 kstat_cpu(j).cpustat.nice;
505 }
506 }
507 this_dbs_info->down_skip = 0;
508 this_dbs_info->requested_freq = policy->cur;
509
510 mutex_init(&this_dbs_info->timer_mutex);
511 dbs_enable++;
512 /*
513 * Start the timerschedule work, when this governor
514 * is used for first time
515 */
516 if (dbs_enable == 1) {
517 unsigned int latency;
518 /* policy latency is in nS. Convert it to uS first */
519 latency = policy->cpuinfo.transition_latency / 1000;
520 if (latency == 0)
521 latency = 1;
522
523 rc = sysfs_create_group(cpufreq_global_kobject,
524 &dbs_attr_group);
525 if (rc) {
526 mutex_unlock(&dbs_mutex);
527 return rc;
528 }
529
530 /*
531 * conservative does not implement micro like ondemand
532 * governor, thus we are bound to jiffes/HZ
533 */
534 min_sampling_rate =
535 MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
536 /* Bring kernel and HW constraints together */
537 min_sampling_rate = max(min_sampling_rate,
538 MIN_LATENCY_MULTIPLIER * latency);
539 dbs_tuners_ins.sampling_rate =
540 max(min_sampling_rate,
541 latency * LATENCY_MULTIPLIER);
542
543 cpufreq_register_notifier(
544 &dbs_cpufreq_notifier_block,
545 CPUFREQ_TRANSITION_NOTIFIER);
546 }
547 mutex_unlock(&dbs_mutex);
548
549 dbs_timer_init(this_dbs_info);
550
551 break;
552
553 case CPUFREQ_GOV_STOP:
554 dbs_timer_exit(this_dbs_info);
555
556 mutex_lock(&dbs_mutex);
557 dbs_enable--;
558 mutex_destroy(&this_dbs_info->timer_mutex);
559
560 /*
561 * Stop the timerschedule work, when this governor
562 * is used for first time
563 */
564 if (dbs_enable == 0)
565 cpufreq_unregister_notifier(
566 &dbs_cpufreq_notifier_block,
567 CPUFREQ_TRANSITION_NOTIFIER);
568
569 mutex_unlock(&dbs_mutex);
570 if (!dbs_enable)
571 sysfs_remove_group(cpufreq_global_kobject,
572 &dbs_attr_group);
573
574 break;
575
576 case CPUFREQ_GOV_LIMITS:
577 mutex_lock(&this_dbs_info->timer_mutex);
578 if (policy->max < this_dbs_info->cur_policy->cur)
579 __cpufreq_driver_target(
580 this_dbs_info->cur_policy,
581 policy->max, CPUFREQ_RELATION_H);
582 else if (policy->min > this_dbs_info->cur_policy->cur)
583 __cpufreq_driver_target(
584 this_dbs_info->cur_policy,
585 policy->min, CPUFREQ_RELATION_L);
586 mutex_unlock(&this_dbs_info->timer_mutex);
587
588 break;
589 }
590 return 0;
591}
592
593#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
594static
595#endif
596struct cpufreq_governor cpufreq_gov_conservative = {
597 .name = "conservative",
598 .governor = cpufreq_governor_dbs,
599 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
600 .owner = THIS_MODULE,
601};
602
603static int __init cpufreq_gov_dbs_init(void)
604{
605 return cpufreq_register_governor(&cpufreq_gov_conservative);
606}
607
608static void __exit cpufreq_gov_dbs_exit(void)
609{
610 cpufreq_unregister_governor(&cpufreq_gov_conservative);
611}
612
613
614MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
615MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
616 "Low Latency Frequency Transition capable processors "
617 "optimised for use in a battery environment");
618MODULE_LICENSE("GPL");
619
620#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
621fs_initcall(cpufreq_gov_dbs_init);
622#else
623module_init(cpufreq_gov_dbs_init);
624#endif
625module_exit(cpufreq_gov_dbs_exit);
1/*
2 * drivers/cpufreq/cpufreq_conservative.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 * (C) 2009 Alexander Clouter <alex@digriz.org.uk>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13
14#include <linux/slab.h>
15#include "cpufreq_governor.h"
16
17struct cs_policy_dbs_info {
18 struct policy_dbs_info policy_dbs;
19 unsigned int down_skip;
20 unsigned int requested_freq;
21};
22
23static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
24{
25 return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
26}
27
28struct cs_dbs_tuners {
29 unsigned int down_threshold;
30 unsigned int freq_step;
31};
32
33/* Conservative governor macros */
34#define DEF_FREQUENCY_UP_THRESHOLD (80)
35#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
36#define DEF_FREQUENCY_STEP (5)
37#define DEF_SAMPLING_DOWN_FACTOR (1)
38#define MAX_SAMPLING_DOWN_FACTOR (10)
39
40static inline unsigned int get_freq_step(struct cs_dbs_tuners *cs_tuners,
41 struct cpufreq_policy *policy)
42{
43 unsigned int freq_step = (cs_tuners->freq_step * policy->max) / 100;
44
45 /* max freq cannot be less than 100. But who knows... */
46 if (unlikely(freq_step == 0))
47 freq_step = DEF_FREQUENCY_STEP;
48
49 return freq_step;
50}
51
52/*
53 * Every sampling_rate, we check, if current idle time is less than 20%
54 * (default), then we try to increase frequency. Every sampling_rate *
55 * sampling_down_factor, we check, if current idle time is more than 80%
56 * (default), then we try to decrease frequency
57 *
58 * Frequency updates happen at minimum steps of 5% (default) of maximum
59 * frequency
60 */
61static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
62{
63 struct policy_dbs_info *policy_dbs = policy->governor_data;
64 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
65 unsigned int requested_freq = dbs_info->requested_freq;
66 struct dbs_data *dbs_data = policy_dbs->dbs_data;
67 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
68 unsigned int load = dbs_update(policy);
69 unsigned int freq_step;
70
71 /*
72 * break out if we 'cannot' reduce the speed as the user might
73 * want freq_step to be zero
74 */
75 if (cs_tuners->freq_step == 0)
76 goto out;
77
78 /*
79 * If requested_freq is out of range, it is likely that the limits
80 * changed in the meantime, so fall back to current frequency in that
81 * case.
82 */
83 if (requested_freq > policy->max || requested_freq < policy->min)
84 requested_freq = policy->cur;
85
86 freq_step = get_freq_step(cs_tuners, policy);
87
88 /*
89 * Decrease requested_freq one freq_step for each idle period that
90 * we didn't update the frequency.
91 */
92 if (policy_dbs->idle_periods < UINT_MAX) {
93 unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
94
95 if (requested_freq > freq_steps)
96 requested_freq -= freq_steps;
97 else
98 requested_freq = policy->min;
99
100 policy_dbs->idle_periods = UINT_MAX;
101 }
102
103 /* Check for frequency increase */
104 if (load > dbs_data->up_threshold) {
105 dbs_info->down_skip = 0;
106
107 /* if we are already at full speed then break out early */
108 if (requested_freq == policy->max)
109 goto out;
110
111 requested_freq += freq_step;
112 if (requested_freq > policy->max)
113 requested_freq = policy->max;
114
115 __cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_H);
116 dbs_info->requested_freq = requested_freq;
117 goto out;
118 }
119
120 /* if sampling_down_factor is active break out early */
121 if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
122 goto out;
123 dbs_info->down_skip = 0;
124
125 /* Check for frequency decrease */
126 if (load < cs_tuners->down_threshold) {
127 /*
128 * if we cannot reduce the frequency anymore, break out early
129 */
130 if (requested_freq == policy->min)
131 goto out;
132
133 if (requested_freq > freq_step)
134 requested_freq -= freq_step;
135 else
136 requested_freq = policy->min;
137
138 __cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_L);
139 dbs_info->requested_freq = requested_freq;
140 }
141
142 out:
143 return dbs_data->sampling_rate;
144}
145
146/************************** sysfs interface ************************/
147
148static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
149 const char *buf, size_t count)
150{
151 struct dbs_data *dbs_data = to_dbs_data(attr_set);
152 unsigned int input;
153 int ret;
154 ret = sscanf(buf, "%u", &input);
155
156 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
157 return -EINVAL;
158
159 dbs_data->sampling_down_factor = input;
160 return count;
161}
162
163static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
164 const char *buf, size_t count)
165{
166 struct dbs_data *dbs_data = to_dbs_data(attr_set);
167 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
168 unsigned int input;
169 int ret;
170 ret = sscanf(buf, "%u", &input);
171
172 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
173 return -EINVAL;
174
175 dbs_data->up_threshold = input;
176 return count;
177}
178
179static ssize_t store_down_threshold(struct gov_attr_set *attr_set,
180 const char *buf, size_t count)
181{
182 struct dbs_data *dbs_data = to_dbs_data(attr_set);
183 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
184 unsigned int input;
185 int ret;
186 ret = sscanf(buf, "%u", &input);
187
188 /* cannot be lower than 11 otherwise freq will not fall */
189 if (ret != 1 || input < 11 || input > 100 ||
190 input >= dbs_data->up_threshold)
191 return -EINVAL;
192
193 cs_tuners->down_threshold = input;
194 return count;
195}
196
197static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
198 const char *buf, size_t count)
199{
200 struct dbs_data *dbs_data = to_dbs_data(attr_set);
201 unsigned int input;
202 int ret;
203
204 ret = sscanf(buf, "%u", &input);
205 if (ret != 1)
206 return -EINVAL;
207
208 if (input > 1)
209 input = 1;
210
211 if (input == dbs_data->ignore_nice_load) /* nothing to do */
212 return count;
213
214 dbs_data->ignore_nice_load = input;
215
216 /* we need to re-evaluate prev_cpu_idle */
217 gov_update_cpu_data(dbs_data);
218
219 return count;
220}
221
222static ssize_t store_freq_step(struct gov_attr_set *attr_set, const char *buf,
223 size_t count)
224{
225 struct dbs_data *dbs_data = to_dbs_data(attr_set);
226 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
227 unsigned int input;
228 int ret;
229 ret = sscanf(buf, "%u", &input);
230
231 if (ret != 1)
232 return -EINVAL;
233
234 if (input > 100)
235 input = 100;
236
237 /*
238 * no need to test here if freq_step is zero as the user might actually
239 * want this, they would be crazy though :)
240 */
241 cs_tuners->freq_step = input;
242 return count;
243}
244
245gov_show_one_common(sampling_rate);
246gov_show_one_common(sampling_down_factor);
247gov_show_one_common(up_threshold);
248gov_show_one_common(ignore_nice_load);
249gov_show_one_common(min_sampling_rate);
250gov_show_one(cs, down_threshold);
251gov_show_one(cs, freq_step);
252
253gov_attr_rw(sampling_rate);
254gov_attr_rw(sampling_down_factor);
255gov_attr_rw(up_threshold);
256gov_attr_rw(ignore_nice_load);
257gov_attr_ro(min_sampling_rate);
258gov_attr_rw(down_threshold);
259gov_attr_rw(freq_step);
260
261static struct attribute *cs_attributes[] = {
262 &min_sampling_rate.attr,
263 &sampling_rate.attr,
264 &sampling_down_factor.attr,
265 &up_threshold.attr,
266 &down_threshold.attr,
267 &ignore_nice_load.attr,
268 &freq_step.attr,
269 NULL
270};
271
272/************************** sysfs end ************************/
273
274static struct policy_dbs_info *cs_alloc(void)
275{
276 struct cs_policy_dbs_info *dbs_info;
277
278 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
279 return dbs_info ? &dbs_info->policy_dbs : NULL;
280}
281
282static void cs_free(struct policy_dbs_info *policy_dbs)
283{
284 kfree(to_dbs_info(policy_dbs));
285}
286
287static int cs_init(struct dbs_data *dbs_data)
288{
289 struct cs_dbs_tuners *tuners;
290
291 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
292 if (!tuners)
293 return -ENOMEM;
294
295 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
296 tuners->freq_step = DEF_FREQUENCY_STEP;
297 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
298 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
299 dbs_data->ignore_nice_load = 0;
300
301 dbs_data->tuners = tuners;
302 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
303 jiffies_to_usecs(10);
304
305 return 0;
306}
307
308static void cs_exit(struct dbs_data *dbs_data)
309{
310 kfree(dbs_data->tuners);
311}
312
313static void cs_start(struct cpufreq_policy *policy)
314{
315 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
316
317 dbs_info->down_skip = 0;
318 dbs_info->requested_freq = policy->cur;
319}
320
321static struct dbs_governor cs_governor = {
322 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
323 .kobj_type = { .default_attrs = cs_attributes },
324 .gov_dbs_update = cs_dbs_update,
325 .alloc = cs_alloc,
326 .free = cs_free,
327 .init = cs_init,
328 .exit = cs_exit,
329 .start = cs_start,
330};
331
332#define CPU_FREQ_GOV_CONSERVATIVE (&cs_governor.gov)
333
334static int __init cpufreq_gov_dbs_init(void)
335{
336 return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
337}
338
339static void __exit cpufreq_gov_dbs_exit(void)
340{
341 cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE);
342}
343
344MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
345MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
346 "Low Latency Frequency Transition capable processors "
347 "optimised for use in a battery environment");
348MODULE_LICENSE("GPL");
349
350#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
351struct cpufreq_governor *cpufreq_default_governor(void)
352{
353 return CPU_FREQ_GOV_CONSERVATIVE;
354}
355
356fs_initcall(cpufreq_gov_dbs_init);
357#else
358module_init(cpufreq_gov_dbs_init);
359#endif
360module_exit(cpufreq_gov_dbs_exit);