[CPUFREQ] checkpatch cleanups for conservative governor
[linux-2.6.git] / drivers / cpufreq / cpufreq_conservative.c
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)  2004 Alexander Clouter <alex-kernel@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/smp.h>
17 #include <linux/init.h>
18 #include <linux/interrupt.h>
19 #include <linux/ctype.h>
20 #include <linux/cpufreq.h>
21 #include <linux/sysctl.h>
22 #include <linux/types.h>
23 #include <linux/fs.h>
24 #include <linux/sysfs.h>
25 #include <linux/cpu.h>
26 #include <linux/kmod.h>
27 #include <linux/workqueue.h>
28 #include <linux/jiffies.h>
29 #include <linux/kernel_stat.h>
30 #include <linux/percpu.h>
31 #include <linux/mutex.h>
32 /*
33  * dbs is used in this file as a shortform for demandbased switching
34  * It helps to keep variable names smaller, simpler
35  */
36
37 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
38 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
39
40 /*
41  * The polling frequency of this governor depends on the capability of
42  * the processor. Default polling frequency is 1000 times the transition
43  * latency of the processor. The governor will work on any processor with
44  * transition latency <= 10mS, using appropriate sampling
45  * rate.
46  * For CPUs with transition latency > 10mS (mostly drivers
47  * with CPUFREQ_ETERNAL), this governor will not work.
48  * All times here are in uS.
49  */
50 static unsigned int def_sampling_rate;
51 #define MIN_SAMPLING_RATE_RATIO                 (2)
52 /* for correct statistics, we need at least 10 ticks between each measure */
53 #define MIN_STAT_SAMPLING_RATE                  \
54                         (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
55 #define MIN_SAMPLING_RATE                       \
56                         (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
57 #define MAX_SAMPLING_RATE                       (500 * def_sampling_rate)
58 #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER    (1000)
59 #define DEF_SAMPLING_DOWN_FACTOR                (1)
60 #define MAX_SAMPLING_DOWN_FACTOR                (10)
61 #define TRANSITION_LATENCY_LIMIT                (10 * 1000 * 1000)
62
63 static void do_dbs_timer(struct work_struct *work);
64
65 struct cpu_dbs_info_s {
66         struct cpufreq_policy *cur_policy;
67         unsigned int prev_cpu_idle_up;
68         unsigned int prev_cpu_idle_down;
69         unsigned int enable;
70         unsigned int down_skip;
71         unsigned int requested_freq;
72 };
73 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
74
75 static unsigned int dbs_enable; /* number of CPUs using this policy */
76
77 /*
78  * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
79  * lock and dbs_mutex. cpu_hotplug lock should always be held before
80  * dbs_mutex. If any function that can potentially take cpu_hotplug lock
81  * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
82  * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
83  * is recursive for the same process. -Venki
84  */
85 static DEFINE_MUTEX(dbs_mutex);
86 static DECLARE_DELAYED_WORK(dbs_work, do_dbs_timer);
87
88 struct dbs_tuners {
89         unsigned int sampling_rate;
90         unsigned int sampling_down_factor;
91         unsigned int up_threshold;
92         unsigned int down_threshold;
93         unsigned int ignore_nice;
94         unsigned int freq_step;
95 };
96
97 static struct dbs_tuners dbs_tuners_ins = {
98         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
99         .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
100         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
101         .ignore_nice = 0,
102         .freq_step = 5,
103 };
104
105 static inline unsigned int get_cpu_idle_time(unsigned int cpu)
106 {
107         unsigned int add_nice = 0, ret;
108
109         if (dbs_tuners_ins.ignore_nice)
110                 add_nice = kstat_cpu(cpu).cpustat.nice;
111
112         ret = kstat_cpu(cpu).cpustat.idle +
113                 kstat_cpu(cpu).cpustat.iowait +
114                 add_nice;
115
116         return ret;
117 }
118
119 /* keep track of frequency transitions */
120 static int
121 dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
122                      void *data)
123 {
124         struct cpufreq_freqs *freq = data;
125         struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info,
126                                                         freq->cpu);
127
128         if (!this_dbs_info->enable)
129                 return 0;
130
131         this_dbs_info->requested_freq = freq->new;
132
133         return 0;
134 }
135
136 static struct notifier_block dbs_cpufreq_notifier_block = {
137         .notifier_call = dbs_cpufreq_notifier
138 };
139
140 /************************** sysfs interface ************************/
141 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
142 {
143         return sprintf(buf, "%u\n", MAX_SAMPLING_RATE);
144 }
145
146 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
147 {
148         return sprintf(buf, "%u\n", MIN_SAMPLING_RATE);
149 }
150
151 #define define_one_ro(_name)                            \
152 static struct freq_attr _name =                         \
153 __ATTR(_name, 0444, show_##_name, NULL)
154
155 define_one_ro(sampling_rate_max);
156 define_one_ro(sampling_rate_min);
157
158 /* cpufreq_conservative Governor Tunables */
159 #define show_one(file_name, object)                                     \
160 static ssize_t show_##file_name                                         \
161 (struct cpufreq_policy *unused, char *buf)                              \
162 {                                                                       \
163         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
164 }
165 show_one(sampling_rate, sampling_rate);
166 show_one(sampling_down_factor, sampling_down_factor);
167 show_one(up_threshold, up_threshold);
168 show_one(down_threshold, down_threshold);
169 show_one(ignore_nice_load, ignore_nice);
170 show_one(freq_step, freq_step);
171
172 static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
173                 const char *buf, size_t count)
174 {
175         unsigned int input;
176         int ret;
177         ret = sscanf(buf, "%u", &input);
178         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
179                 return -EINVAL;
180
181         mutex_lock(&dbs_mutex);
182         dbs_tuners_ins.sampling_down_factor = input;
183         mutex_unlock(&dbs_mutex);
184
185         return count;
186 }
187
188 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
189                 const char *buf, size_t count)
190 {
191         unsigned int input;
192         int ret;
193         ret = sscanf(buf, "%u", &input);
194
195         mutex_lock(&dbs_mutex);
196         if (ret != 1 || input > MAX_SAMPLING_RATE ||
197             input < MIN_SAMPLING_RATE) {
198                 mutex_unlock(&dbs_mutex);
199                 return -EINVAL;
200         }
201
202         dbs_tuners_ins.sampling_rate = input;
203         mutex_unlock(&dbs_mutex);
204
205         return count;
206 }
207
208 static ssize_t store_up_threshold(struct cpufreq_policy *unused,
209                 const char *buf, size_t count)
210 {
211         unsigned int input;
212         int ret;
213         ret = sscanf(buf, "%u", &input);
214
215         mutex_lock(&dbs_mutex);
216         if (ret != 1 || input > 100 ||
217             input <= dbs_tuners_ins.down_threshold) {
218                 mutex_unlock(&dbs_mutex);
219                 return -EINVAL;
220         }
221
222         dbs_tuners_ins.up_threshold = input;
223         mutex_unlock(&dbs_mutex);
224
225         return count;
226 }
227
228 static ssize_t store_down_threshold(struct cpufreq_policy *unused,
229                 const char *buf, size_t count)
230 {
231         unsigned int input;
232         int ret;
233         ret = sscanf(buf, "%u", &input);
234
235         mutex_lock(&dbs_mutex);
236         if (ret != 1 || input > 100 || input >= dbs_tuners_ins.up_threshold) {
237                 mutex_unlock(&dbs_mutex);
238                 return -EINVAL;
239         }
240
241         dbs_tuners_ins.down_threshold = input;
242         mutex_unlock(&dbs_mutex);
243
244         return count;
245 }
246
247 static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
248                 const char *buf, size_t count)
249 {
250         unsigned int input;
251         int ret;
252
253         unsigned int j;
254
255         ret = sscanf(buf, "%u", &input);
256         if (ret != 1)
257                 return -EINVAL;
258
259         if (input > 1)
260                 input = 1;
261
262         mutex_lock(&dbs_mutex);
263         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
264                 mutex_unlock(&dbs_mutex);
265                 return count;
266         }
267         dbs_tuners_ins.ignore_nice = input;
268
269         /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
270         for_each_online_cpu(j) {
271                 struct cpu_dbs_info_s *j_dbs_info;
272                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
273                 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
274                 j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
275         }
276         mutex_unlock(&dbs_mutex);
277
278         return count;
279 }
280
281 static ssize_t store_freq_step(struct cpufreq_policy *policy,
282                 const char *buf, size_t count)
283 {
284         unsigned int input;
285         int ret;
286
287         ret = sscanf(buf, "%u", &input);
288
289         if (ret != 1)
290                 return -EINVAL;
291
292         if (input > 100)
293                 input = 100;
294
295         /* no need to test here if freq_step is zero as the user might actually
296          * want this, they would be crazy though :) */
297         mutex_lock(&dbs_mutex);
298         dbs_tuners_ins.freq_step = input;
299         mutex_unlock(&dbs_mutex);
300
301         return count;
302 }
303
304 #define define_one_rw(_name) \
305 static struct freq_attr _name = \
306 __ATTR(_name, 0644, show_##_name, store_##_name)
307
308 define_one_rw(sampling_rate);
309 define_one_rw(sampling_down_factor);
310 define_one_rw(up_threshold);
311 define_one_rw(down_threshold);
312 define_one_rw(ignore_nice_load);
313 define_one_rw(freq_step);
314
315 static struct attribute *dbs_attributes[] = {
316         &sampling_rate_max.attr,
317         &sampling_rate_min.attr,
318         &sampling_rate.attr,
319         &sampling_down_factor.attr,
320         &up_threshold.attr,
321         &down_threshold.attr,
322         &ignore_nice_load.attr,
323         &freq_step.attr,
324         NULL
325 };
326
327 static struct attribute_group dbs_attr_group = {
328         .attrs = dbs_attributes,
329         .name = "conservative",
330 };
331
332 /************************** sysfs end ************************/
333
334 static void dbs_check_cpu(int cpu)
335 {
336         unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
337         unsigned int tmp_idle_ticks, total_idle_ticks;
338         unsigned int freq_target;
339         unsigned int freq_down_sampling_rate;
340         struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
341         struct cpufreq_policy *policy;
342
343         if (!this_dbs_info->enable)
344                 return;
345
346         policy = this_dbs_info->cur_policy;
347
348         /*
349          * The default safe range is 20% to 80%
350          * Every sampling_rate, we check
351          *      - If current idle time is less than 20%, then we try to
352          *        increase frequency
353          * Every sampling_rate*sampling_down_factor, we check
354          *      - If current idle time is more than 80%, then we try to
355          *        decrease frequency
356          *
357          * Any frequency increase takes it to the maximum frequency.
358          * Frequency reduction happens at minimum steps of
359          * 5% (default) of max_frequency
360          */
361
362         /* Check for frequency increase */
363         idle_ticks = UINT_MAX;
364
365         /* Check for frequency increase */
366         total_idle_ticks = get_cpu_idle_time(cpu);
367         tmp_idle_ticks = total_idle_ticks -
368                 this_dbs_info->prev_cpu_idle_up;
369         this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
370
371         if (tmp_idle_ticks < idle_ticks)
372                 idle_ticks = tmp_idle_ticks;
373
374         /* Scale idle ticks by 100 and compare with up and down ticks */
375         idle_ticks *= 100;
376         up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
377                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
378
379         if (idle_ticks < up_idle_ticks) {
380                 this_dbs_info->down_skip = 0;
381                 this_dbs_info->prev_cpu_idle_down =
382                         this_dbs_info->prev_cpu_idle_up;
383
384                 /* if we are already at full speed then break out early */
385                 if (this_dbs_info->requested_freq == policy->max)
386                         return;
387
388                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
389
390                 /* max freq cannot be less than 100. But who knows.... */
391                 if (unlikely(freq_target == 0))
392                         freq_target = 5;
393
394                 this_dbs_info->requested_freq += freq_target;
395                 if (this_dbs_info->requested_freq > policy->max)
396                         this_dbs_info->requested_freq = policy->max;
397
398                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
399                         CPUFREQ_RELATION_H);
400                 return;
401         }
402
403         /* Check for frequency decrease */
404         this_dbs_info->down_skip++;
405         if (this_dbs_info->down_skip < dbs_tuners_ins.sampling_down_factor)
406                 return;
407
408         /* Check for frequency decrease */
409         total_idle_ticks = this_dbs_info->prev_cpu_idle_up;
410         tmp_idle_ticks = total_idle_ticks -
411                 this_dbs_info->prev_cpu_idle_down;
412         this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
413
414         if (tmp_idle_ticks < idle_ticks)
415                 idle_ticks = tmp_idle_ticks;
416
417         /* Scale idle ticks by 100 and compare with up and down ticks */
418         idle_ticks *= 100;
419         this_dbs_info->down_skip = 0;
420
421         freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
422                 dbs_tuners_ins.sampling_down_factor;
423         down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
424                 usecs_to_jiffies(freq_down_sampling_rate);
425
426         if (idle_ticks > down_idle_ticks) {
427                 /*
428                  * if we are already at the lowest speed then break out early
429                  * or if we 'cannot' reduce the speed as the user might want
430                  * freq_target to be zero
431                  */
432                 if (this_dbs_info->requested_freq == policy->min
433                                 || dbs_tuners_ins.freq_step == 0)
434                         return;
435
436                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
437
438                 /* max freq cannot be less than 100. But who knows.... */
439                 if (unlikely(freq_target == 0))
440                         freq_target = 5;
441
442                 this_dbs_info->requested_freq -= freq_target;
443                 if (this_dbs_info->requested_freq < policy->min)
444                         this_dbs_info->requested_freq = policy->min;
445
446                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
447                                 CPUFREQ_RELATION_H);
448                 return;
449         }
450 }
451
452 static void do_dbs_timer(struct work_struct *work)
453 {
454         int i;
455         mutex_lock(&dbs_mutex);
456         for_each_online_cpu(i)
457                 dbs_check_cpu(i);
458         schedule_delayed_work(&dbs_work,
459                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
460         mutex_unlock(&dbs_mutex);
461 }
462
463 static inline void dbs_timer_init(void)
464 {
465         init_timer_deferrable(&dbs_work.timer);
466         schedule_delayed_work(&dbs_work,
467                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
468         return;
469 }
470
471 static inline void dbs_timer_exit(void)
472 {
473         cancel_delayed_work(&dbs_work);
474         return;
475 }
476
477 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
478                                    unsigned int event)
479 {
480         unsigned int cpu = policy->cpu;
481         struct cpu_dbs_info_s *this_dbs_info;
482         unsigned int j;
483         int rc;
484
485         this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
486
487         switch (event) {
488         case CPUFREQ_GOV_START:
489                 if ((!cpu_online(cpu)) || (!policy->cur))
490                         return -EINVAL;
491
492                 if (this_dbs_info->enable) /* Already enabled */
493                         break;
494
495                 mutex_lock(&dbs_mutex);
496
497                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
498                 if (rc) {
499                         mutex_unlock(&dbs_mutex);
500                         return rc;
501                 }
502
503                 for_each_cpu(j, policy->cpus) {
504                         struct cpu_dbs_info_s *j_dbs_info;
505                         j_dbs_info = &per_cpu(cpu_dbs_info, j);
506                         j_dbs_info->cur_policy = policy;
507
508                         j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(cpu);
509                         j_dbs_info->prev_cpu_idle_down
510                                 = j_dbs_info->prev_cpu_idle_up;
511                 }
512                 this_dbs_info->enable = 1;
513                 this_dbs_info->down_skip = 0;
514                 this_dbs_info->requested_freq = policy->cur;
515
516                 dbs_enable++;
517                 /*
518                  * Start the timerschedule work, when this governor
519                  * is used for first time
520                  */
521                 if (dbs_enable == 1) {
522                         unsigned int latency;
523                         /* policy latency is in nS. Convert it to uS first */
524                         latency = policy->cpuinfo.transition_latency / 1000;
525                         if (latency == 0)
526                                 latency = 1;
527
528                         def_sampling_rate = 10 * latency *
529                                         DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
530
531                         if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
532                                 def_sampling_rate = MIN_STAT_SAMPLING_RATE;
533
534                         dbs_tuners_ins.sampling_rate = def_sampling_rate;
535
536                         dbs_timer_init();
537                         cpufreq_register_notifier(
538                                         &dbs_cpufreq_notifier_block,
539                                         CPUFREQ_TRANSITION_NOTIFIER);
540                 }
541
542                 mutex_unlock(&dbs_mutex);
543                 break;
544
545         case CPUFREQ_GOV_STOP:
546                 mutex_lock(&dbs_mutex);
547                 this_dbs_info->enable = 0;
548                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
549                 dbs_enable--;
550                 /*
551                  * Stop the timerschedule work, when this governor
552                  * is used for first time
553                  */
554                 if (dbs_enable == 0) {
555                         dbs_timer_exit();
556                         cpufreq_unregister_notifier(
557                                         &dbs_cpufreq_notifier_block,
558                                         CPUFREQ_TRANSITION_NOTIFIER);
559                 }
560
561                 mutex_unlock(&dbs_mutex);
562
563                 break;
564
565         case CPUFREQ_GOV_LIMITS:
566                 mutex_lock(&dbs_mutex);
567                 if (policy->max < this_dbs_info->cur_policy->cur)
568                         __cpufreq_driver_target(
569                                         this_dbs_info->cur_policy,
570                                         policy->max, CPUFREQ_RELATION_H);
571                 else if (policy->min > this_dbs_info->cur_policy->cur)
572                         __cpufreq_driver_target(
573                                         this_dbs_info->cur_policy,
574                                         policy->min, CPUFREQ_RELATION_L);
575                 mutex_unlock(&dbs_mutex);
576                 break;
577         }
578         return 0;
579 }
580
581 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
582 static
583 #endif
584 struct cpufreq_governor cpufreq_gov_conservative = {
585         .name                   = "conservative",
586         .governor               = cpufreq_governor_dbs,
587         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
588         .owner                  = THIS_MODULE,
589 };
590
591 static int __init cpufreq_gov_dbs_init(void)
592 {
593         return cpufreq_register_governor(&cpufreq_gov_conservative);
594 }
595
596 static void __exit cpufreq_gov_dbs_exit(void)
597 {
598         /* Make sure that the scheduled work is indeed not running */
599         flush_scheduled_work();
600
601         cpufreq_unregister_governor(&cpufreq_gov_conservative);
602 }
603
604
605 MODULE_AUTHOR("Alexander Clouter <alex-kernel@digriz.org.uk>");
606 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
607                 "Low Latency Frequency Transition capable processors "
608                 "optimised for use in a battery environment");
609 MODULE_LICENSE("GPL");
610
611 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
612 fs_initcall(cpufreq_gov_dbs_init);
613 #else
614 module_init(cpufreq_gov_dbs_init);
615 #endif
616 module_exit(cpufreq_gov_dbs_exit);