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1da177e4 LT |
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/smp.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/interrupt.h> | |
18 | #include <linux/ctype.h> | |
19 | #include <linux/cpufreq.h> | |
20 | #include <linux/sysctl.h> | |
21 | #include <linux/types.h> | |
22 | #include <linux/fs.h> | |
23 | #include <linux/sysfs.h> | |
24 | #include <linux/sched.h> | |
25 | #include <linux/kmod.h> | |
26 | #include <linux/workqueue.h> | |
27 | #include <linux/jiffies.h> | |
28 | #include <linux/kernel_stat.h> | |
29 | #include <linux/percpu.h> | |
30 | ||
31 | /* | |
32 | * dbs is used in this file as a shortform for demandbased switching | |
33 | * It helps to keep variable names smaller, simpler | |
34 | */ | |
35 | ||
36 | #define DEF_FREQUENCY_UP_THRESHOLD (80) | |
37 | #define MIN_FREQUENCY_UP_THRESHOLD (0) | |
38 | #define MAX_FREQUENCY_UP_THRESHOLD (100) | |
39 | ||
40 | #define DEF_FREQUENCY_DOWN_THRESHOLD (20) | |
41 | #define MIN_FREQUENCY_DOWN_THRESHOLD (0) | |
42 | #define MAX_FREQUENCY_DOWN_THRESHOLD (100) | |
43 | ||
44 | /* | |
45 | * The polling frequency of this governor depends on the capability of | |
46 | * the processor. Default polling frequency is 1000 times the transition | |
47 | * latency of the processor. The governor will work on any processor with | |
48 | * transition latency <= 10mS, using appropriate sampling | |
49 | * rate. | |
50 | * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL) | |
51 | * this governor will not work. | |
52 | * All times here are in uS. | |
53 | */ | |
54 | static unsigned int def_sampling_rate; | |
55 | #define MIN_SAMPLING_RATE (def_sampling_rate / 2) | |
56 | #define MAX_SAMPLING_RATE (500 * def_sampling_rate) | |
57 | #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000) | |
58 | #define DEF_SAMPLING_DOWN_FACTOR (10) | |
59 | #define TRANSITION_LATENCY_LIMIT (10 * 1000) | |
1da177e4 LT |
60 | |
61 | static void do_dbs_timer(void *data); | |
62 | ||
63 | struct cpu_dbs_info_s { | |
64 | struct cpufreq_policy *cur_policy; | |
65 | unsigned int prev_cpu_idle_up; | |
66 | unsigned int prev_cpu_idle_down; | |
67 | unsigned int enable; | |
68 | }; | |
69 | static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info); | |
70 | ||
71 | static unsigned int dbs_enable; /* number of CPUs using this policy */ | |
72 | ||
73 | static DECLARE_MUTEX (dbs_sem); | |
74 | static DECLARE_WORK (dbs_work, do_dbs_timer, NULL); | |
75 | ||
76 | struct dbs_tuners { | |
77 | unsigned int sampling_rate; | |
78 | unsigned int sampling_down_factor; | |
79 | unsigned int up_threshold; | |
80 | unsigned int down_threshold; | |
3d5ee9e5 | 81 | unsigned int ignore_nice; |
1206aaac | 82 | unsigned int freq_step; |
1da177e4 LT |
83 | }; |
84 | ||
85 | static struct dbs_tuners dbs_tuners_ins = { | |
86 | .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, | |
87 | .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD, | |
88 | .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, | |
89 | }; | |
90 | ||
dac1c1a5 DJ |
91 | static inline unsigned int get_cpu_idle_time(unsigned int cpu) |
92 | { | |
93 | return kstat_cpu(cpu).cpustat.idle + | |
94 | kstat_cpu(cpu).cpustat.iowait + | |
95 | ( !dbs_tuners_ins.ignore_nice ? | |
96 | kstat_cpu(cpu).cpustat.nice : | |
97 | 0); | |
98 | } | |
99 | ||
1da177e4 LT |
100 | /************************** sysfs interface ************************/ |
101 | static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf) | |
102 | { | |
103 | return sprintf (buf, "%u\n", MAX_SAMPLING_RATE); | |
104 | } | |
105 | ||
106 | static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf) | |
107 | { | |
108 | return sprintf (buf, "%u\n", MIN_SAMPLING_RATE); | |
109 | } | |
110 | ||
111 | #define define_one_ro(_name) \ | |
112 | static struct freq_attr _name = \ | |
113 | __ATTR(_name, 0444, show_##_name, NULL) | |
114 | ||
115 | define_one_ro(sampling_rate_max); | |
116 | define_one_ro(sampling_rate_min); | |
117 | ||
118 | /* cpufreq_ondemand Governor Tunables */ | |
119 | #define show_one(file_name, object) \ | |
120 | static ssize_t show_##file_name \ | |
121 | (struct cpufreq_policy *unused, char *buf) \ | |
122 | { \ | |
123 | return sprintf(buf, "%u\n", dbs_tuners_ins.object); \ | |
124 | } | |
125 | show_one(sampling_rate, sampling_rate); | |
126 | show_one(sampling_down_factor, sampling_down_factor); | |
127 | show_one(up_threshold, up_threshold); | |
128 | show_one(down_threshold, down_threshold); | |
3d5ee9e5 | 129 | show_one(ignore_nice, ignore_nice); |
1206aaac | 130 | show_one(freq_step, freq_step); |
1da177e4 LT |
131 | |
132 | static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused, | |
133 | const char *buf, size_t count) | |
134 | { | |
135 | unsigned int input; | |
136 | int ret; | |
137 | ret = sscanf (buf, "%u", &input); | |
138 | if (ret != 1 ) | |
139 | return -EINVAL; | |
140 | ||
141 | down(&dbs_sem); | |
142 | dbs_tuners_ins.sampling_down_factor = input; | |
143 | up(&dbs_sem); | |
144 | ||
145 | return count; | |
146 | } | |
147 | ||
148 | static ssize_t store_sampling_rate(struct cpufreq_policy *unused, | |
149 | const char *buf, size_t count) | |
150 | { | |
151 | unsigned int input; | |
152 | int ret; | |
153 | ret = sscanf (buf, "%u", &input); | |
154 | ||
155 | down(&dbs_sem); | |
156 | if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) { | |
157 | up(&dbs_sem); | |
158 | return -EINVAL; | |
159 | } | |
160 | ||
161 | dbs_tuners_ins.sampling_rate = input; | |
162 | up(&dbs_sem); | |
163 | ||
164 | return count; | |
165 | } | |
166 | ||
167 | static ssize_t store_up_threshold(struct cpufreq_policy *unused, | |
168 | const char *buf, size_t count) | |
169 | { | |
170 | unsigned int input; | |
171 | int ret; | |
172 | ret = sscanf (buf, "%u", &input); | |
173 | ||
174 | down(&dbs_sem); | |
175 | if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || | |
176 | input < MIN_FREQUENCY_UP_THRESHOLD || | |
177 | input <= dbs_tuners_ins.down_threshold) { | |
178 | up(&dbs_sem); | |
179 | return -EINVAL; | |
180 | } | |
181 | ||
182 | dbs_tuners_ins.up_threshold = input; | |
183 | up(&dbs_sem); | |
184 | ||
185 | return count; | |
186 | } | |
187 | ||
188 | static ssize_t store_down_threshold(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 | down(&dbs_sem); | |
196 | if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD || | |
197 | input < MIN_FREQUENCY_DOWN_THRESHOLD || | |
198 | input >= dbs_tuners_ins.up_threshold) { | |
199 | up(&dbs_sem); | |
200 | return -EINVAL; | |
201 | } | |
202 | ||
203 | dbs_tuners_ins.down_threshold = input; | |
204 | up(&dbs_sem); | |
205 | ||
206 | return count; | |
207 | } | |
208 | ||
3d5ee9e5 DJ |
209 | static ssize_t store_ignore_nice(struct cpufreq_policy *policy, |
210 | const char *buf, size_t count) | |
211 | { | |
212 | unsigned int input; | |
213 | int ret; | |
214 | ||
215 | unsigned int j; | |
216 | ||
217 | ret = sscanf (buf, "%u", &input); | |
218 | if ( ret != 1 ) | |
219 | return -EINVAL; | |
220 | ||
221 | if ( input > 1 ) | |
222 | input = 1; | |
223 | ||
224 | down(&dbs_sem); | |
225 | if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */ | |
226 | up(&dbs_sem); | |
227 | return count; | |
228 | } | |
229 | dbs_tuners_ins.ignore_nice = input; | |
230 | ||
231 | /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */ | |
dac1c1a5 | 232 | for_each_online_cpu(j) { |
3d5ee9e5 DJ |
233 | struct cpu_dbs_info_s *j_dbs_info; |
234 | j_dbs_info = &per_cpu(cpu_dbs_info, j); | |
dac1c1a5 | 235 | j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j); |
3d5ee9e5 DJ |
236 | j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up; |
237 | } | |
238 | up(&dbs_sem); | |
239 | ||
240 | return count; | |
241 | } | |
242 | ||
1206aaac DJ |
243 | static ssize_t store_freq_step(struct cpufreq_policy *policy, |
244 | const char *buf, size_t count) | |
245 | { | |
246 | unsigned int input; | |
247 | int ret; | |
248 | ||
249 | ret = sscanf (buf, "%u", &input); | |
250 | ||
251 | if ( ret != 1 ) | |
252 | return -EINVAL; | |
253 | ||
254 | if ( input > 100 ) | |
255 | input = 100; | |
256 | ||
257 | /* no need to test here if freq_step is zero as the user might actually | |
258 | * want this, they would be crazy though :) */ | |
259 | down(&dbs_sem); | |
260 | dbs_tuners_ins.freq_step = input; | |
261 | up(&dbs_sem); | |
262 | ||
263 | return count; | |
264 | } | |
265 | ||
1da177e4 LT |
266 | #define define_one_rw(_name) \ |
267 | static struct freq_attr _name = \ | |
268 | __ATTR(_name, 0644, show_##_name, store_##_name) | |
269 | ||
270 | define_one_rw(sampling_rate); | |
271 | define_one_rw(sampling_down_factor); | |
272 | define_one_rw(up_threshold); | |
273 | define_one_rw(down_threshold); | |
3d5ee9e5 | 274 | define_one_rw(ignore_nice); |
1206aaac | 275 | define_one_rw(freq_step); |
1da177e4 LT |
276 | |
277 | static struct attribute * dbs_attributes[] = { | |
278 | &sampling_rate_max.attr, | |
279 | &sampling_rate_min.attr, | |
280 | &sampling_rate.attr, | |
281 | &sampling_down_factor.attr, | |
282 | &up_threshold.attr, | |
283 | &down_threshold.attr, | |
3d5ee9e5 | 284 | &ignore_nice.attr, |
1206aaac | 285 | &freq_step.attr, |
1da177e4 LT |
286 | NULL |
287 | }; | |
288 | ||
289 | static struct attribute_group dbs_attr_group = { | |
290 | .attrs = dbs_attributes, | |
291 | .name = "ondemand", | |
292 | }; | |
293 | ||
294 | /************************** sysfs end ************************/ | |
295 | ||
296 | static void dbs_check_cpu(int cpu) | |
297 | { | |
298 | unsigned int idle_ticks, up_idle_ticks, down_idle_ticks; | |
1da177e4 LT |
299 | unsigned int freq_down_step; |
300 | unsigned int freq_down_sampling_rate; | |
301 | static int down_skip[NR_CPUS]; | |
302 | struct cpu_dbs_info_s *this_dbs_info; | |
303 | ||
304 | struct cpufreq_policy *policy; | |
305 | unsigned int j; | |
306 | ||
307 | this_dbs_info = &per_cpu(cpu_dbs_info, cpu); | |
308 | if (!this_dbs_info->enable) | |
309 | return; | |
310 | ||
311 | policy = this_dbs_info->cur_policy; | |
312 | /* | |
313 | * The default safe range is 20% to 80% | |
314 | * Every sampling_rate, we check | |
315 | * - If current idle time is less than 20%, then we try to | |
316 | * increase frequency | |
317 | * Every sampling_rate*sampling_down_factor, we check | |
318 | * - If current idle time is more than 80%, then we try to | |
319 | * decrease frequency | |
320 | * | |
321 | * Any frequency increase takes it to the maximum frequency. | |
322 | * Frequency reduction happens at minimum steps of | |
1206aaac | 323 | * 5% (default) of max_frequency |
1da177e4 LT |
324 | */ |
325 | ||
326 | /* Check for frequency increase */ | |
9c7d269b | 327 | idle_ticks = UINT_MAX; |
1da177e4 | 328 | for_each_cpu_mask(j, policy->cpus) { |
9c7d269b | 329 | unsigned int tmp_idle_ticks, total_idle_ticks; |
1da177e4 LT |
330 | struct cpu_dbs_info_s *j_dbs_info; |
331 | ||
1da177e4 | 332 | j_dbs_info = &per_cpu(cpu_dbs_info, j); |
dac1c1a5 | 333 | total_idle_ticks = get_cpu_idle_time(j); |
1da177e4 LT |
334 | tmp_idle_ticks = total_idle_ticks - |
335 | j_dbs_info->prev_cpu_idle_up; | |
336 | j_dbs_info->prev_cpu_idle_up = total_idle_ticks; | |
337 | ||
338 | if (tmp_idle_ticks < idle_ticks) | |
339 | idle_ticks = tmp_idle_ticks; | |
340 | } | |
341 | ||
342 | /* Scale idle ticks by 100 and compare with up and down ticks */ | |
343 | idle_ticks *= 100; | |
344 | up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) * | |
6fe71165 | 345 | usecs_to_jiffies(dbs_tuners_ins.sampling_rate); |
1da177e4 LT |
346 | |
347 | if (idle_ticks < up_idle_ticks) { | |
dac1c1a5 | 348 | down_skip[cpu] = 0; |
790d76fa DJ |
349 | for_each_cpu_mask(j, policy->cpus) { |
350 | struct cpu_dbs_info_s *j_dbs_info; | |
351 | ||
352 | j_dbs_info = &per_cpu(cpu_dbs_info, j); | |
353 | j_dbs_info->prev_cpu_idle_down = | |
354 | j_dbs_info->prev_cpu_idle_up; | |
355 | } | |
c11420a6 DJ |
356 | /* if we are already at full speed then break out early */ |
357 | if (policy->cur == policy->max) | |
358 | return; | |
359 | ||
1da177e4 LT |
360 | __cpufreq_driver_target(policy, policy->max, |
361 | CPUFREQ_RELATION_H); | |
1da177e4 LT |
362 | return; |
363 | } | |
364 | ||
365 | /* Check for frequency decrease */ | |
366 | down_skip[cpu]++; | |
367 | if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor) | |
368 | return; | |
369 | ||
9c7d269b | 370 | idle_ticks = UINT_MAX; |
1da177e4 | 371 | for_each_cpu_mask(j, policy->cpus) { |
9c7d269b | 372 | unsigned int tmp_idle_ticks, total_idle_ticks; |
1da177e4 LT |
373 | struct cpu_dbs_info_s *j_dbs_info; |
374 | ||
1da177e4 | 375 | j_dbs_info = &per_cpu(cpu_dbs_info, j); |
dac1c1a5 DJ |
376 | /* Check for frequency decrease */ |
377 | total_idle_ticks = j_dbs_info->prev_cpu_idle_up; | |
1da177e4 LT |
378 | tmp_idle_ticks = total_idle_ticks - |
379 | j_dbs_info->prev_cpu_idle_down; | |
380 | j_dbs_info->prev_cpu_idle_down = total_idle_ticks; | |
381 | ||
382 | if (tmp_idle_ticks < idle_ticks) | |
383 | idle_ticks = tmp_idle_ticks; | |
384 | } | |
385 | ||
386 | /* Scale idle ticks by 100 and compare with up and down ticks */ | |
387 | idle_ticks *= 100; | |
388 | down_skip[cpu] = 0; | |
389 | ||
390 | freq_down_sampling_rate = dbs_tuners_ins.sampling_rate * | |
391 | dbs_tuners_ins.sampling_down_factor; | |
392 | down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) * | |
dac1c1a5 | 393 | usecs_to_jiffies(freq_down_sampling_rate); |
1da177e4 | 394 | |
9c7d269b | 395 | if (idle_ticks > down_idle_ticks) { |
1206aaac DJ |
396 | /* if we are already at the lowest speed then break out early |
397 | * or if we 'cannot' reduce the speed as the user might want | |
398 | * freq_step to be zero */ | |
399 | if (policy->cur == policy->min || dbs_tuners_ins.freq_step == 0) | |
c11420a6 | 400 | return; |
1206aaac DJ |
401 | |
402 | freq_down_step = (dbs_tuners_ins.freq_step * policy->max) / 100; | |
1da177e4 LT |
403 | |
404 | /* max freq cannot be less than 100. But who knows.... */ | |
405 | if (unlikely(freq_down_step == 0)) | |
406 | freq_down_step = 5; | |
407 | ||
408 | __cpufreq_driver_target(policy, | |
1206aaac | 409 | policy->cur - freq_down_step, |
1da177e4 LT |
410 | CPUFREQ_RELATION_H); |
411 | return; | |
412 | } | |
413 | } | |
414 | ||
415 | static void do_dbs_timer(void *data) | |
416 | { | |
417 | int i; | |
418 | down(&dbs_sem); | |
6fe71165 DJ |
419 | for_each_online_cpu(i) |
420 | dbs_check_cpu(i); | |
1da177e4 | 421 | schedule_delayed_work(&dbs_work, |
6fe71165 | 422 | usecs_to_jiffies(dbs_tuners_ins.sampling_rate)); |
1da177e4 LT |
423 | up(&dbs_sem); |
424 | } | |
425 | ||
426 | static inline void dbs_timer_init(void) | |
427 | { | |
428 | INIT_WORK(&dbs_work, do_dbs_timer, NULL); | |
429 | schedule_delayed_work(&dbs_work, | |
6fe71165 | 430 | usecs_to_jiffies(dbs_tuners_ins.sampling_rate)); |
1da177e4 LT |
431 | return; |
432 | } | |
433 | ||
434 | static inline void dbs_timer_exit(void) | |
435 | { | |
436 | cancel_delayed_work(&dbs_work); | |
437 | return; | |
438 | } | |
439 | ||
440 | static int cpufreq_governor_dbs(struct cpufreq_policy *policy, | |
441 | unsigned int event) | |
442 | { | |
443 | unsigned int cpu = policy->cpu; | |
444 | struct cpu_dbs_info_s *this_dbs_info; | |
445 | unsigned int j; | |
446 | ||
447 | this_dbs_info = &per_cpu(cpu_dbs_info, cpu); | |
448 | ||
449 | switch (event) { | |
450 | case CPUFREQ_GOV_START: | |
451 | if ((!cpu_online(cpu)) || | |
452 | (!policy->cur)) | |
453 | return -EINVAL; | |
454 | ||
455 | if (policy->cpuinfo.transition_latency > | |
456 | (TRANSITION_LATENCY_LIMIT * 1000)) | |
457 | return -EINVAL; | |
458 | if (this_dbs_info->enable) /* Already enabled */ | |
459 | break; | |
460 | ||
461 | down(&dbs_sem); | |
462 | for_each_cpu_mask(j, policy->cpus) { | |
463 | struct cpu_dbs_info_s *j_dbs_info; | |
464 | j_dbs_info = &per_cpu(cpu_dbs_info, j); | |
465 | j_dbs_info->cur_policy = policy; | |
466 | ||
dac1c1a5 | 467 | j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j); |
3d5ee9e5 DJ |
468 | j_dbs_info->prev_cpu_idle_down |
469 | = j_dbs_info->prev_cpu_idle_up; | |
1da177e4 LT |
470 | } |
471 | this_dbs_info->enable = 1; | |
472 | sysfs_create_group(&policy->kobj, &dbs_attr_group); | |
473 | dbs_enable++; | |
474 | /* | |
475 | * Start the timerschedule work, when this governor | |
476 | * is used for first time | |
477 | */ | |
478 | if (dbs_enable == 1) { | |
479 | unsigned int latency; | |
480 | /* policy latency is in nS. Convert it to uS first */ | |
481 | ||
482 | latency = policy->cpuinfo.transition_latency; | |
483 | if (latency < 1000) | |
484 | latency = 1000; | |
485 | ||
486 | def_sampling_rate = (latency / 1000) * | |
487 | DEF_SAMPLING_RATE_LATENCY_MULTIPLIER; | |
488 | dbs_tuners_ins.sampling_rate = def_sampling_rate; | |
3d5ee9e5 | 489 | dbs_tuners_ins.ignore_nice = 0; |
1206aaac | 490 | dbs_tuners_ins.freq_step = 5; |
1da177e4 LT |
491 | |
492 | dbs_timer_init(); | |
493 | } | |
494 | ||
495 | up(&dbs_sem); | |
496 | break; | |
497 | ||
498 | case CPUFREQ_GOV_STOP: | |
499 | down(&dbs_sem); | |
500 | this_dbs_info->enable = 0; | |
501 | sysfs_remove_group(&policy->kobj, &dbs_attr_group); | |
502 | dbs_enable--; | |
503 | /* | |
504 | * Stop the timerschedule work, when this governor | |
505 | * is used for first time | |
506 | */ | |
507 | if (dbs_enable == 0) | |
508 | dbs_timer_exit(); | |
509 | ||
510 | up(&dbs_sem); | |
511 | ||
512 | break; | |
513 | ||
514 | case CPUFREQ_GOV_LIMITS: | |
515 | down(&dbs_sem); | |
516 | if (policy->max < this_dbs_info->cur_policy->cur) | |
517 | __cpufreq_driver_target( | |
518 | this_dbs_info->cur_policy, | |
519 | policy->max, CPUFREQ_RELATION_H); | |
520 | else if (policy->min > this_dbs_info->cur_policy->cur) | |
521 | __cpufreq_driver_target( | |
522 | this_dbs_info->cur_policy, | |
523 | policy->min, CPUFREQ_RELATION_L); | |
524 | up(&dbs_sem); | |
525 | break; | |
526 | } | |
527 | return 0; | |
528 | } | |
529 | ||
7f335d4e | 530 | static struct cpufreq_governor cpufreq_gov_dbs = { |
1da177e4 LT |
531 | .name = "ondemand", |
532 | .governor = cpufreq_governor_dbs, | |
533 | .owner = THIS_MODULE, | |
534 | }; | |
1da177e4 LT |
535 | |
536 | static int __init cpufreq_gov_dbs_init(void) | |
537 | { | |
538 | return cpufreq_register_governor(&cpufreq_gov_dbs); | |
539 | } | |
540 | ||
541 | static void __exit cpufreq_gov_dbs_exit(void) | |
542 | { | |
543 | /* Make sure that the scheduled work is indeed not running */ | |
544 | flush_scheduled_work(); | |
545 | ||
546 | cpufreq_unregister_governor(&cpufreq_gov_dbs); | |
547 | } | |
548 | ||
549 | ||
550 | MODULE_AUTHOR ("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>"); | |
551 | MODULE_DESCRIPTION ("'cpufreq_ondemand' - A dynamic cpufreq governor for " | |
552 | "Low Latency Frequency Transition capable processors"); | |
553 | MODULE_LICENSE ("GPL"); | |
554 | ||
555 | module_init(cpufreq_gov_dbs_init); | |
556 | module_exit(cpufreq_gov_dbs_exit); |