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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) 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/sched.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 | ||
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 MIN_FREQUENCY_UP_THRESHOLD (0) | |
39 | #define MAX_FREQUENCY_UP_THRESHOLD (100) | |
40 | ||
41 | #define DEF_FREQUENCY_DOWN_THRESHOLD (20) | |
42 | #define MIN_FREQUENCY_DOWN_THRESHOLD (0) | |
43 | #define MAX_FREQUENCY_DOWN_THRESHOLD (100) | |
44 | ||
45 | /* | |
46 | * The polling frequency of this governor depends on the capability of | |
47 | * the processor. Default polling frequency is 1000 times the transition | |
48 | * latency of the processor. The governor will work on any processor with | |
49 | * transition latency <= 10mS, using appropriate sampling | |
50 | * rate. | |
51 | * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL) | |
52 | * this governor will not work. | |
53 | * All times here are in uS. | |
54 | */ | |
55 | static unsigned int def_sampling_rate; | |
56 | #define MIN_SAMPLING_RATE (def_sampling_rate / 2) | |
57 | #define MAX_SAMPLING_RATE (500 * def_sampling_rate) | |
58 | #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (100000) | |
59 | #define DEF_SAMPLING_DOWN_FACTOR (5) | |
60 | #define TRANSITION_LATENCY_LIMIT (10 * 1000) | |
61 | ||
62 | static void do_dbs_timer(void *data); | |
63 | ||
64 | struct cpu_dbs_info_s { | |
65 | struct cpufreq_policy *cur_policy; | |
66 | unsigned int prev_cpu_idle_up; | |
67 | unsigned int prev_cpu_idle_down; | |
68 | unsigned int enable; | |
69 | }; | |
70 | static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info); | |
71 | ||
72 | static unsigned int dbs_enable; /* number of CPUs using this policy */ | |
73 | ||
74 | static DECLARE_MUTEX (dbs_sem); | |
75 | static DECLARE_WORK (dbs_work, do_dbs_timer, NULL); | |
76 | ||
77 | struct dbs_tuners { | |
78 | unsigned int sampling_rate; | |
79 | unsigned int sampling_down_factor; | |
80 | unsigned int up_threshold; | |
81 | unsigned int down_threshold; | |
82 | unsigned int ignore_nice; | |
83 | unsigned int freq_step; | |
84 | }; | |
85 | ||
86 | static struct dbs_tuners dbs_tuners_ins = { | |
87 | .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, | |
88 | .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD, | |
89 | .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, | |
90 | }; | |
91 | ||
92 | /************************** sysfs interface ************************/ | |
93 | static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf) | |
94 | { | |
95 | return sprintf (buf, "%u\n", MAX_SAMPLING_RATE); | |
96 | } | |
97 | ||
98 | static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf) | |
99 | { | |
100 | return sprintf (buf, "%u\n", MIN_SAMPLING_RATE); | |
101 | } | |
102 | ||
103 | #define define_one_ro(_name) \ | |
104 | static struct freq_attr _name = \ | |
105 | __ATTR(_name, 0444, show_##_name, NULL) | |
106 | ||
107 | define_one_ro(sampling_rate_max); | |
108 | define_one_ro(sampling_rate_min); | |
109 | ||
110 | /* cpufreq_conservative Governor Tunables */ | |
111 | #define show_one(file_name, object) \ | |
112 | static ssize_t show_##file_name \ | |
113 | (struct cpufreq_policy *unused, char *buf) \ | |
114 | { \ | |
115 | return sprintf(buf, "%u\n", dbs_tuners_ins.object); \ | |
116 | } | |
117 | show_one(sampling_rate, sampling_rate); | |
118 | show_one(sampling_down_factor, sampling_down_factor); | |
119 | show_one(up_threshold, up_threshold); | |
120 | show_one(down_threshold, down_threshold); | |
121 | show_one(ignore_nice, ignore_nice); | |
122 | show_one(freq_step, freq_step); | |
123 | ||
124 | static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused, | |
125 | const char *buf, size_t count) | |
126 | { | |
127 | unsigned int input; | |
128 | int ret; | |
129 | ret = sscanf (buf, "%u", &input); | |
130 | if (ret != 1 ) | |
131 | return -EINVAL; | |
132 | ||
133 | down(&dbs_sem); | |
134 | dbs_tuners_ins.sampling_down_factor = input; | |
135 | up(&dbs_sem); | |
136 | ||
137 | return count; | |
138 | } | |
139 | ||
140 | static ssize_t store_sampling_rate(struct cpufreq_policy *unused, | |
141 | const char *buf, size_t count) | |
142 | { | |
143 | unsigned int input; | |
144 | int ret; | |
145 | ret = sscanf (buf, "%u", &input); | |
146 | ||
147 | down(&dbs_sem); | |
148 | if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) { | |
149 | up(&dbs_sem); | |
150 | return -EINVAL; | |
151 | } | |
152 | ||
153 | dbs_tuners_ins.sampling_rate = input; | |
154 | up(&dbs_sem); | |
155 | ||
156 | return count; | |
157 | } | |
158 | ||
159 | static ssize_t store_up_threshold(struct cpufreq_policy *unused, | |
160 | const char *buf, size_t count) | |
161 | { | |
162 | unsigned int input; | |
163 | int ret; | |
164 | ret = sscanf (buf, "%u", &input); | |
165 | ||
166 | down(&dbs_sem); | |
167 | if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || | |
168 | input < MIN_FREQUENCY_UP_THRESHOLD || | |
169 | input <= dbs_tuners_ins.down_threshold) { | |
170 | up(&dbs_sem); | |
171 | return -EINVAL; | |
172 | } | |
173 | ||
174 | dbs_tuners_ins.up_threshold = input; | |
175 | up(&dbs_sem); | |
176 | ||
177 | return count; | |
178 | } | |
179 | ||
180 | static ssize_t store_down_threshold(struct cpufreq_policy *unused, | |
181 | const char *buf, size_t count) | |
182 | { | |
183 | unsigned int input; | |
184 | int ret; | |
185 | ret = sscanf (buf, "%u", &input); | |
186 | ||
187 | down(&dbs_sem); | |
188 | if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD || | |
189 | input < MIN_FREQUENCY_DOWN_THRESHOLD || | |
190 | input >= dbs_tuners_ins.up_threshold) { | |
191 | up(&dbs_sem); | |
192 | return -EINVAL; | |
193 | } | |
194 | ||
195 | dbs_tuners_ins.down_threshold = input; | |
196 | up(&dbs_sem); | |
197 | ||
198 | return count; | |
199 | } | |
200 | ||
201 | static ssize_t store_ignore_nice(struct cpufreq_policy *policy, | |
202 | const char *buf, size_t count) | |
203 | { | |
204 | unsigned int input; | |
205 | int ret; | |
206 | ||
207 | unsigned int j; | |
208 | ||
209 | ret = sscanf (buf, "%u", &input); | |
210 | if ( ret != 1 ) | |
211 | return -EINVAL; | |
212 | ||
213 | if ( input > 1 ) | |
214 | input = 1; | |
215 | ||
216 | down(&dbs_sem); | |
217 | if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */ | |
218 | up(&dbs_sem); | |
219 | return count; | |
220 | } | |
221 | dbs_tuners_ins.ignore_nice = input; | |
222 | ||
223 | /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */ | |
224 | for_each_cpu_mask(j, policy->cpus) { | |
225 | struct cpu_dbs_info_s *j_dbs_info; | |
226 | j_dbs_info = &per_cpu(cpu_dbs_info, j); | |
227 | j_dbs_info->cur_policy = policy; | |
228 | ||
229 | j_dbs_info->prev_cpu_idle_up = | |
230 | kstat_cpu(j).cpustat.idle + | |
231 | kstat_cpu(j).cpustat.iowait + | |
232 | ( !dbs_tuners_ins.ignore_nice | |
233 | ? kstat_cpu(j).cpustat.nice : 0 ); | |
234 | j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up; | |
235 | } | |
236 | up(&dbs_sem); | |
237 | ||
238 | return count; | |
239 | } | |
240 | ||
241 | static ssize_t store_freq_step(struct cpufreq_policy *policy, | |
242 | const char *buf, size_t count) | |
243 | { | |
244 | unsigned int input; | |
245 | int ret; | |
246 | ||
247 | ret = sscanf (buf, "%u", &input); | |
248 | ||
249 | if ( ret != 1 ) | |
250 | return -EINVAL; | |
251 | ||
252 | if ( input > 100 ) | |
253 | input = 100; | |
254 | ||
255 | /* no need to test here if freq_step is zero as the user might actually | |
256 | * want this, they would be crazy though :) */ | |
257 | down(&dbs_sem); | |
258 | dbs_tuners_ins.freq_step = input; | |
259 | up(&dbs_sem); | |
260 | ||
261 | return count; | |
262 | } | |
263 | ||
264 | #define define_one_rw(_name) \ | |
265 | static struct freq_attr _name = \ | |
266 | __ATTR(_name, 0644, show_##_name, store_##_name) | |
267 | ||
268 | define_one_rw(sampling_rate); | |
269 | define_one_rw(sampling_down_factor); | |
270 | define_one_rw(up_threshold); | |
271 | define_one_rw(down_threshold); | |
272 | define_one_rw(ignore_nice); | |
273 | define_one_rw(freq_step); | |
274 | ||
275 | static struct attribute * dbs_attributes[] = { | |
276 | &sampling_rate_max.attr, | |
277 | &sampling_rate_min.attr, | |
278 | &sampling_rate.attr, | |
279 | &sampling_down_factor.attr, | |
280 | &up_threshold.attr, | |
281 | &down_threshold.attr, | |
282 | &ignore_nice.attr, | |
283 | &freq_step.attr, | |
284 | NULL | |
285 | }; | |
286 | ||
287 | static struct attribute_group dbs_attr_group = { | |
288 | .attrs = dbs_attributes, | |
289 | .name = "conservative", | |
290 | }; | |
291 | ||
292 | /************************** sysfs end ************************/ | |
293 | ||
294 | static void dbs_check_cpu(int cpu) | |
295 | { | |
296 | unsigned int idle_ticks, up_idle_ticks, down_idle_ticks; | |
297 | unsigned int total_idle_ticks; | |
298 | unsigned int freq_step; | |
299 | unsigned int freq_down_sampling_rate; | |
300 | static int down_skip[NR_CPUS]; | |
301 | static int requested_freq[NR_CPUS]; | |
302 | static unsigned short init_flag = 0; | |
303 | struct cpu_dbs_info_s *this_dbs_info; | |
304 | struct cpu_dbs_info_s *dbs_info; | |
305 | ||
306 | struct cpufreq_policy *policy; | |
307 | unsigned int j; | |
308 | ||
309 | this_dbs_info = &per_cpu(cpu_dbs_info, cpu); | |
310 | if (!this_dbs_info->enable) | |
311 | return; | |
312 | ||
313 | policy = this_dbs_info->cur_policy; | |
314 | ||
315 | if ( init_flag == 0 ) { | |
316 | for ( /* NULL */; init_flag < NR_CPUS; init_flag++ ) { | |
317 | dbs_info = &per_cpu(cpu_dbs_info, init_flag); | |
318 | requested_freq[cpu] = dbs_info->cur_policy->cur; | |
319 | } | |
320 | init_flag = 1; | |
321 | } | |
322 | ||
323 | /* | |
324 | * The default safe range is 20% to 80% | |
325 | * Every sampling_rate, we check | |
326 | * - If current idle time is less than 20%, then we try to | |
327 | * increase frequency | |
328 | * Every sampling_rate*sampling_down_factor, we check | |
329 | * - If current idle time is more than 80%, then we try to | |
330 | * decrease frequency | |
331 | * | |
332 | * Any frequency increase takes it to the maximum frequency. | |
333 | * Frequency reduction happens at minimum steps of | |
334 | * 5% (default) of max_frequency | |
335 | */ | |
336 | ||
337 | /* Check for frequency increase */ | |
338 | total_idle_ticks = kstat_cpu(cpu).cpustat.idle + | |
339 | kstat_cpu(cpu).cpustat.iowait; | |
340 | /* consider 'nice' tasks as 'idle' time too if required */ | |
341 | if (dbs_tuners_ins.ignore_nice == 0) | |
342 | total_idle_ticks += kstat_cpu(cpu).cpustat.nice; | |
343 | idle_ticks = total_idle_ticks - | |
344 | this_dbs_info->prev_cpu_idle_up; | |
345 | this_dbs_info->prev_cpu_idle_up = total_idle_ticks; | |
346 | ||
347 | ||
348 | for_each_cpu_mask(j, policy->cpus) { | |
349 | unsigned int tmp_idle_ticks; | |
350 | struct cpu_dbs_info_s *j_dbs_info; | |
351 | ||
352 | if (j == cpu) | |
353 | continue; | |
354 | ||
355 | j_dbs_info = &per_cpu(cpu_dbs_info, j); | |
356 | /* Check for frequency increase */ | |
357 | total_idle_ticks = kstat_cpu(j).cpustat.idle + | |
358 | kstat_cpu(j).cpustat.iowait; | |
359 | /* consider 'nice' too? */ | |
360 | if (dbs_tuners_ins.ignore_nice == 0) | |
361 | total_idle_ticks += kstat_cpu(j).cpustat.nice; | |
362 | tmp_idle_ticks = total_idle_ticks - | |
363 | j_dbs_info->prev_cpu_idle_up; | |
364 | j_dbs_info->prev_cpu_idle_up = total_idle_ticks; | |
365 | ||
366 | if (tmp_idle_ticks < idle_ticks) | |
367 | idle_ticks = tmp_idle_ticks; | |
368 | } | |
369 | ||
370 | /* Scale idle ticks by 100 and compare with up and down ticks */ | |
371 | idle_ticks *= 100; | |
372 | up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) * | |
373 | usecs_to_jiffies(dbs_tuners_ins.sampling_rate); | |
374 | ||
375 | if (idle_ticks < up_idle_ticks) { | |
376 | /* if we are already at full speed then break out early */ | |
377 | if (requested_freq[cpu] == policy->max) | |
378 | return; | |
379 | ||
380 | freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100; | |
381 | ||
382 | /* max freq cannot be less than 100. But who knows.... */ | |
383 | if (unlikely(freq_step == 0)) | |
384 | freq_step = 5; | |
385 | ||
386 | requested_freq[cpu] += freq_step; | |
387 | if (requested_freq[cpu] > policy->max) | |
388 | requested_freq[cpu] = policy->max; | |
389 | ||
390 | __cpufreq_driver_target(policy, requested_freq[cpu], | |
391 | CPUFREQ_RELATION_H); | |
392 | down_skip[cpu] = 0; | |
393 | this_dbs_info->prev_cpu_idle_down = total_idle_ticks; | |
394 | return; | |
395 | } | |
396 | ||
397 | /* Check for frequency decrease */ | |
398 | down_skip[cpu]++; | |
399 | if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor) | |
400 | return; | |
401 | ||
402 | total_idle_ticks = kstat_cpu(cpu).cpustat.idle + | |
403 | kstat_cpu(cpu).cpustat.iowait; | |
404 | /* consider 'nice' too? */ | |
405 | if (dbs_tuners_ins.ignore_nice == 0) | |
406 | total_idle_ticks += kstat_cpu(cpu).cpustat.nice; | |
407 | idle_ticks = total_idle_ticks - | |
408 | this_dbs_info->prev_cpu_idle_down; | |
409 | this_dbs_info->prev_cpu_idle_down = total_idle_ticks; | |
410 | ||
411 | for_each_cpu_mask(j, policy->cpus) { | |
412 | unsigned int tmp_idle_ticks; | |
413 | struct cpu_dbs_info_s *j_dbs_info; | |
414 | ||
415 | if (j == cpu) | |
416 | continue; | |
417 | ||
418 | j_dbs_info = &per_cpu(cpu_dbs_info, j); | |
419 | /* Check for frequency increase */ | |
420 | total_idle_ticks = kstat_cpu(j).cpustat.idle + | |
421 | kstat_cpu(j).cpustat.iowait; | |
422 | /* consider 'nice' too? */ | |
423 | if (dbs_tuners_ins.ignore_nice == 0) | |
424 | total_idle_ticks += kstat_cpu(j).cpustat.nice; | |
425 | tmp_idle_ticks = total_idle_ticks - | |
426 | j_dbs_info->prev_cpu_idle_down; | |
427 | j_dbs_info->prev_cpu_idle_down = total_idle_ticks; | |
428 | ||
429 | if (tmp_idle_ticks < idle_ticks) | |
430 | idle_ticks = tmp_idle_ticks; | |
431 | } | |
432 | ||
433 | /* Scale idle ticks by 100 and compare with up and down ticks */ | |
434 | idle_ticks *= 100; | |
435 | down_skip[cpu] = 0; | |
436 | ||
437 | freq_down_sampling_rate = dbs_tuners_ins.sampling_rate * | |
438 | dbs_tuners_ins.sampling_down_factor; | |
439 | down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) * | |
440 | usecs_to_jiffies(freq_down_sampling_rate); | |
441 | ||
442 | if (idle_ticks > down_idle_ticks ) { | |
443 | /* if we are already at the lowest speed then break out early | |
444 | * or if we 'cannot' reduce the speed as the user might want | |
445 | * freq_step to be zero */ | |
446 | if (requested_freq[cpu] == policy->min | |
447 | || dbs_tuners_ins.freq_step == 0) | |
448 | return; | |
449 | ||
450 | freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100; | |
451 | ||
452 | /* max freq cannot be less than 100. But who knows.... */ | |
453 | if (unlikely(freq_step == 0)) | |
454 | freq_step = 5; | |
455 | ||
456 | requested_freq[cpu] -= freq_step; | |
457 | if (requested_freq[cpu] < policy->min) | |
458 | requested_freq[cpu] = policy->min; | |
459 | ||
460 | __cpufreq_driver_target(policy, | |
461 | requested_freq[cpu], | |
462 | CPUFREQ_RELATION_H); | |
463 | return; | |
464 | } | |
465 | } | |
466 | ||
467 | static void do_dbs_timer(void *data) | |
468 | { | |
469 | int i; | |
470 | down(&dbs_sem); | |
471 | for_each_online_cpu(i) | |
472 | dbs_check_cpu(i); | |
473 | schedule_delayed_work(&dbs_work, | |
474 | usecs_to_jiffies(dbs_tuners_ins.sampling_rate)); | |
475 | up(&dbs_sem); | |
476 | } | |
477 | ||
478 | static inline void dbs_timer_init(void) | |
479 | { | |
480 | INIT_WORK(&dbs_work, do_dbs_timer, NULL); | |
481 | schedule_delayed_work(&dbs_work, | |
482 | usecs_to_jiffies(dbs_tuners_ins.sampling_rate)); | |
483 | return; | |
484 | } | |
485 | ||
486 | static inline void dbs_timer_exit(void) | |
487 | { | |
488 | cancel_delayed_work(&dbs_work); | |
489 | return; | |
490 | } | |
491 | ||
492 | static int cpufreq_governor_dbs(struct cpufreq_policy *policy, | |
493 | unsigned int event) | |
494 | { | |
495 | unsigned int cpu = policy->cpu; | |
496 | struct cpu_dbs_info_s *this_dbs_info; | |
497 | unsigned int j; | |
498 | ||
499 | this_dbs_info = &per_cpu(cpu_dbs_info, cpu); | |
500 | ||
501 | switch (event) { | |
502 | case CPUFREQ_GOV_START: | |
503 | if ((!cpu_online(cpu)) || | |
504 | (!policy->cur)) | |
505 | return -EINVAL; | |
506 | ||
507 | if (policy->cpuinfo.transition_latency > | |
508 | (TRANSITION_LATENCY_LIMIT * 1000)) | |
509 | return -EINVAL; | |
510 | if (this_dbs_info->enable) /* Already enabled */ | |
511 | break; | |
512 | ||
513 | down(&dbs_sem); | |
514 | for_each_cpu_mask(j, policy->cpus) { | |
515 | struct cpu_dbs_info_s *j_dbs_info; | |
516 | j_dbs_info = &per_cpu(cpu_dbs_info, j); | |
517 | j_dbs_info->cur_policy = policy; | |
518 | ||
519 | j_dbs_info->prev_cpu_idle_up = | |
520 | kstat_cpu(j).cpustat.idle + | |
521 | kstat_cpu(j).cpustat.iowait + | |
522 | ( !dbs_tuners_ins.ignore_nice | |
523 | ? kstat_cpu(j).cpustat.nice : 0 ); | |
524 | j_dbs_info->prev_cpu_idle_down | |
525 | = j_dbs_info->prev_cpu_idle_up; | |
526 | } | |
527 | this_dbs_info->enable = 1; | |
528 | sysfs_create_group(&policy->kobj, &dbs_attr_group); | |
529 | dbs_enable++; | |
530 | /* | |
531 | * Start the timerschedule work, when this governor | |
532 | * is used for first time | |
533 | */ | |
534 | if (dbs_enable == 1) { | |
535 | unsigned int latency; | |
536 | /* policy latency is in nS. Convert it to uS first */ | |
537 | ||
538 | latency = policy->cpuinfo.transition_latency; | |
539 | if (latency < 1000) | |
540 | latency = 1000; | |
541 | ||
542 | def_sampling_rate = (latency / 1000) * | |
543 | DEF_SAMPLING_RATE_LATENCY_MULTIPLIER; | |
544 | dbs_tuners_ins.sampling_rate = def_sampling_rate; | |
545 | dbs_tuners_ins.ignore_nice = 0; | |
546 | dbs_tuners_ins.freq_step = 5; | |
547 | ||
548 | dbs_timer_init(); | |
549 | } | |
550 | ||
551 | up(&dbs_sem); | |
552 | break; | |
553 | ||
554 | case CPUFREQ_GOV_STOP: | |
555 | down(&dbs_sem); | |
556 | this_dbs_info->enable = 0; | |
557 | sysfs_remove_group(&policy->kobj, &dbs_attr_group); | |
558 | dbs_enable--; | |
559 | /* | |
560 | * Stop the timerschedule work, when this governor | |
561 | * is used for first time | |
562 | */ | |
563 | if (dbs_enable == 0) | |
564 | dbs_timer_exit(); | |
565 | ||
566 | up(&dbs_sem); | |
567 | ||
568 | break; | |
569 | ||
570 | case CPUFREQ_GOV_LIMITS: | |
571 | down(&dbs_sem); | |
572 | if (policy->max < this_dbs_info->cur_policy->cur) | |
573 | __cpufreq_driver_target( | |
574 | this_dbs_info->cur_policy, | |
575 | policy->max, CPUFREQ_RELATION_H); | |
576 | else if (policy->min > this_dbs_info->cur_policy->cur) | |
577 | __cpufreq_driver_target( | |
578 | this_dbs_info->cur_policy, | |
579 | policy->min, CPUFREQ_RELATION_L); | |
580 | up(&dbs_sem); | |
581 | break; | |
582 | } | |
583 | return 0; | |
584 | } | |
585 | ||
586 | static struct cpufreq_governor cpufreq_gov_dbs = { | |
587 | .name = "conservative", | |
588 | .governor = cpufreq_governor_dbs, | |
589 | .owner = THIS_MODULE, | |
590 | }; | |
591 | ||
592 | static int __init cpufreq_gov_dbs_init(void) | |
593 | { | |
594 | return cpufreq_register_governor(&cpufreq_gov_dbs); | |
595 | } | |
596 | ||
597 | static void __exit cpufreq_gov_dbs_exit(void) | |
598 | { | |
599 | /* Make sure that the scheduled work is indeed not running */ | |
600 | flush_scheduled_work(); | |
601 | ||
602 | cpufreq_unregister_governor(&cpufreq_gov_dbs); | |
603 | } | |
604 | ||
605 | ||
606 | MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>"); | |
607 | MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for " | |
608 | "Low Latency Frequency Transition capable processors " | |
609 | "optimised for use in a battery environment"); | |
610 | MODULE_LICENSE ("GPL"); | |
611 | ||
612 | module_init(cpufreq_gov_dbs_init); | |
613 | module_exit(cpufreq_gov_dbs_exit); |