blob: 26f440ccc3fb358e9525ecabee819ae52b7afa26 [file] [log] [blame]
Dave Jonesb9170832005-05-31 19:03:47 -07001/*
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>
Andrew Morton138a01282006-06-23 03:31:19 -070025#include <linux/cpu.h>
Dave Jonesb9170832005-05-31 19:03:47 -070026#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>
akpm@osdl.org3fc54d32006-01-13 15:54:22 -080031#include <linux/mutex.h>
Dave Jonesb9170832005-05-31 19:03:47 -070032/*
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)
Dave Jonesb9170832005-05-31 19:03:47 -070038#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
Dave Jonesb9170832005-05-31 19:03:47 -070039
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.
Gautham R Shenoye08f5f52006-10-26 16:20:58 +053046 * For CPUs with transition latency > 10mS (mostly drivers
47 * with CPUFREQ_ETERNAL), this governor will not work.
Dave Jonesb9170832005-05-31 19:03:47 -070048 * All times here are in uS.
49 */
50static unsigned int def_sampling_rate;
Alexander Clouter2c906b32006-03-22 09:54:10 +000051#define MIN_SAMPLING_RATE_RATIO (2)
52/* for correct statistics, we need at least 10 ticks between each measure */
Gautham R Shenoye08f5f52006-10-26 16:20:58 +053053#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)
Dave Jonesb9170832005-05-31 19:03:47 -070057#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
Alexander Clouter2c906b32006-03-22 09:54:10 +000058#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000)
59#define DEF_SAMPLING_DOWN_FACTOR (1)
60#define MAX_SAMPLING_DOWN_FACTOR (10)
Dave Jonesb9170832005-05-31 19:03:47 -070061#define TRANSITION_LATENCY_LIMIT (10 * 1000)
62
David Howellsc4028952006-11-22 14:57:56 +000063static void do_dbs_timer(struct work_struct *work);
Dave Jonesb9170832005-05-31 19:03:47 -070064
65struct 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;
Alexander Cloutera159b822006-03-22 10:00:18 +000070 unsigned int down_skip;
71 unsigned int requested_freq;
Dave Jonesb9170832005-05-31 19:03:47 -070072};
73static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
74
75static unsigned int dbs_enable; /* number of CPUs using this policy */
76
Venkatesh Pallipadi4ec223d2006-06-21 15:18:34 -070077/*
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 */
akpm@osdl.org3fc54d32006-01-13 15:54:22 -080085static DEFINE_MUTEX (dbs_mutex);
David Howellsc4028952006-11-22 14:57:56 +000086static DECLARE_DELAYED_WORK(dbs_work, do_dbs_timer);
Dave Jonesb9170832005-05-31 19:03:47 -070087
88struct 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
97static 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,
Mattia Dongilic326e272006-03-27 22:55:55 +0200101 .ignore_nice = 0,
102 .freq_step = 5,
Dave Jonesb9170832005-05-31 19:03:47 -0700103};
104
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700105static inline unsigned int get_cpu_idle_time(unsigned int cpu)
106{
Gautham R Shenoye08f5f52006-10-26 16:20:58 +0530107 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 +
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700113 kstat_cpu(cpu).cpustat.iowait +
Gautham R Shenoye08f5f52006-10-26 16:20:58 +0530114 add_nice;
115
116 return ret;
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700117}
118
Dave Jonesb9170832005-05-31 19:03:47 -0700119/************************** sysfs interface ************************/
120static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
121{
122 return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
123}
124
125static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
126{
127 return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
128}
129
130#define define_one_ro(_name) \
131static struct freq_attr _name = \
132__ATTR(_name, 0444, show_##_name, NULL)
133
134define_one_ro(sampling_rate_max);
135define_one_ro(sampling_rate_min);
136
137/* cpufreq_conservative Governor Tunables */
138#define show_one(file_name, object) \
139static ssize_t show_##file_name \
140(struct cpufreq_policy *unused, char *buf) \
141{ \
142 return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
143}
144show_one(sampling_rate, sampling_rate);
145show_one(sampling_down_factor, sampling_down_factor);
146show_one(up_threshold, up_threshold);
147show_one(down_threshold, down_threshold);
Alexander Clouter001893c2005-12-01 01:09:25 -0800148show_one(ignore_nice_load, ignore_nice);
Dave Jonesb9170832005-05-31 19:03:47 -0700149show_one(freq_step, freq_step);
150
151static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
152 const char *buf, size_t count)
153{
154 unsigned int input;
155 int ret;
156 ret = sscanf (buf, "%u", &input);
Alexander Clouter2c906b32006-03-22 09:54:10 +0000157 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
Dave Jonesb9170832005-05-31 19:03:47 -0700158 return -EINVAL;
159
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800160 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700161 dbs_tuners_ins.sampling_down_factor = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800162 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700163
164 return count;
165}
166
167static ssize_t store_sampling_rate(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
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800174 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700175 if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800176 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700177 return -EINVAL;
178 }
179
180 dbs_tuners_ins.sampling_rate = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800181 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700182
183 return count;
184}
185
186static ssize_t store_up_threshold(struct cpufreq_policy *unused,
187 const char *buf, size_t count)
188{
189 unsigned int input;
190 int ret;
191 ret = sscanf (buf, "%u", &input);
192
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800193 mutex_lock(&dbs_mutex);
Dave Jonesb82fbe62006-04-01 22:07:07 -0500194 if (ret != 1 || input > 100 || input <= dbs_tuners_ins.down_threshold) {
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800195 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700196 return -EINVAL;
197 }
198
199 dbs_tuners_ins.up_threshold = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800200 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700201
202 return count;
203}
204
205static ssize_t store_down_threshold(struct cpufreq_policy *unused,
206 const char *buf, size_t count)
207{
208 unsigned int input;
209 int ret;
210 ret = sscanf (buf, "%u", &input);
211
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800212 mutex_lock(&dbs_mutex);
Dave Jonesb82fbe62006-04-01 22:07:07 -0500213 if (ret != 1 || input > 100 || input >= dbs_tuners_ins.up_threshold) {
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800214 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700215 return -EINVAL;
216 }
217
218 dbs_tuners_ins.down_threshold = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800219 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700220
221 return count;
222}
223
Alexander Clouter001893c2005-12-01 01:09:25 -0800224static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
Dave Jonesb9170832005-05-31 19:03:47 -0700225 const char *buf, size_t count)
226{
227 unsigned int input;
228 int ret;
229
230 unsigned int j;
231
232 ret = sscanf (buf, "%u", &input);
233 if ( ret != 1 )
234 return -EINVAL;
235
236 if ( input > 1 )
237 input = 1;
238
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800239 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700240 if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800241 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700242 return count;
243 }
244 dbs_tuners_ins.ignore_nice = input;
245
246 /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700247 for_each_online_cpu(j) {
Dave Jonesb9170832005-05-31 19:03:47 -0700248 struct cpu_dbs_info_s *j_dbs_info;
249 j_dbs_info = &per_cpu(cpu_dbs_info, j);
Dave Jonesdac1c1a2005-05-31 19:03:49 -0700250 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
Dave Jonesb9170832005-05-31 19:03:47 -0700251 j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
252 }
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800253 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700254
255 return count;
256}
257
258static ssize_t store_freq_step(struct cpufreq_policy *policy,
259 const char *buf, size_t count)
260{
261 unsigned int input;
262 int ret;
263
264 ret = sscanf (buf, "%u", &input);
265
266 if ( ret != 1 )
267 return -EINVAL;
268
269 if ( input > 100 )
270 input = 100;
271
272 /* no need to test here if freq_step is zero as the user might actually
273 * want this, they would be crazy though :) */
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800274 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700275 dbs_tuners_ins.freq_step = input;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800276 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700277
278 return count;
279}
280
281#define define_one_rw(_name) \
282static struct freq_attr _name = \
283__ATTR(_name, 0644, show_##_name, store_##_name)
284
285define_one_rw(sampling_rate);
286define_one_rw(sampling_down_factor);
287define_one_rw(up_threshold);
288define_one_rw(down_threshold);
Alexander Clouter001893c2005-12-01 01:09:25 -0800289define_one_rw(ignore_nice_load);
Dave Jonesb9170832005-05-31 19:03:47 -0700290define_one_rw(freq_step);
291
292static struct attribute * dbs_attributes[] = {
293 &sampling_rate_max.attr,
294 &sampling_rate_min.attr,
295 &sampling_rate.attr,
296 &sampling_down_factor.attr,
297 &up_threshold.attr,
298 &down_threshold.attr,
Alexander Clouter001893c2005-12-01 01:09:25 -0800299 &ignore_nice_load.attr,
Dave Jonesb9170832005-05-31 19:03:47 -0700300 &freq_step.attr,
301 NULL
302};
303
304static struct attribute_group dbs_attr_group = {
305 .attrs = dbs_attributes,
306 .name = "conservative",
307};
308
309/************************** sysfs end ************************/
310
311static void dbs_check_cpu(int cpu)
312{
313 unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
Alexander Clouter08a28e22006-03-22 09:59:16 +0000314 unsigned int tmp_idle_ticks, total_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700315 unsigned int freq_step;
316 unsigned int freq_down_sampling_rate;
Alexander Clouter08a28e22006-03-22 09:59:16 +0000317 struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
Dave Jonesb9170832005-05-31 19:03:47 -0700318 struct cpufreq_policy *policy;
Dave Jonesb9170832005-05-31 19:03:47 -0700319
Dave Jonesb9170832005-05-31 19:03:47 -0700320 if (!this_dbs_info->enable)
321 return;
322
Alexander Clouter08a28e22006-03-22 09:59:16 +0000323 policy = this_dbs_info->cur_policy;
324
Dave Jonesb9170832005-05-31 19:03:47 -0700325 /*
326 * The default safe range is 20% to 80%
327 * Every sampling_rate, we check
328 * - If current idle time is less than 20%, then we try to
329 * increase frequency
330 * Every sampling_rate*sampling_down_factor, we check
331 * - If current idle time is more than 80%, then we try to
332 * decrease frequency
333 *
334 * Any frequency increase takes it to the maximum frequency.
335 * Frequency reduction happens at minimum steps of
336 * 5% (default) of max_frequency
337 */
338
339 /* Check for frequency increase */
Dave Jones9c7d2692005-05-31 19:03:49 -0700340 idle_ticks = UINT_MAX;
Dave Jonesb9170832005-05-31 19:03:47 -0700341
Alexander Clouter08a28e22006-03-22 09:59:16 +0000342 /* Check for frequency increase */
343 total_idle_ticks = get_cpu_idle_time(cpu);
344 tmp_idle_ticks = total_idle_ticks -
345 this_dbs_info->prev_cpu_idle_up;
346 this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700347
Alexander Clouter08a28e22006-03-22 09:59:16 +0000348 if (tmp_idle_ticks < idle_ticks)
349 idle_ticks = tmp_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700350
351 /* Scale idle ticks by 100 and compare with up and down ticks */
352 idle_ticks *= 100;
353 up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
Alexander Clouter2c906b32006-03-22 09:54:10 +0000354 usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
Dave Jonesb9170832005-05-31 19:03:47 -0700355
356 if (idle_ticks < up_idle_ticks) {
Alexander Cloutera159b822006-03-22 10:00:18 +0000357 this_dbs_info->down_skip = 0;
Alexander Clouter08a28e22006-03-22 09:59:16 +0000358 this_dbs_info->prev_cpu_idle_down =
359 this_dbs_info->prev_cpu_idle_up;
Dave Jones790d76f2005-05-31 19:03:49 -0700360
Dave Jonesb9170832005-05-31 19:03:47 -0700361 /* if we are already at full speed then break out early */
Alexander Cloutera159b822006-03-22 10:00:18 +0000362 if (this_dbs_info->requested_freq == policy->max)
Dave Jonesb9170832005-05-31 19:03:47 -0700363 return;
364
365 freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
366
367 /* max freq cannot be less than 100. But who knows.... */
368 if (unlikely(freq_step == 0))
369 freq_step = 5;
370
Alexander Cloutera159b822006-03-22 10:00:18 +0000371 this_dbs_info->requested_freq += freq_step;
372 if (this_dbs_info->requested_freq > policy->max)
373 this_dbs_info->requested_freq = policy->max;
Dave Jonesb9170832005-05-31 19:03:47 -0700374
Alexander Cloutera159b822006-03-22 10:00:18 +0000375 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
Dave Jonesb9170832005-05-31 19:03:47 -0700376 CPUFREQ_RELATION_H);
Dave Jonesb9170832005-05-31 19:03:47 -0700377 return;
378 }
379
380 /* Check for frequency decrease */
Alexander Cloutera159b822006-03-22 10:00:18 +0000381 this_dbs_info->down_skip++;
382 if (this_dbs_info->down_skip < dbs_tuners_ins.sampling_down_factor)
Dave Jonesb9170832005-05-31 19:03:47 -0700383 return;
384
Alexander Clouter08a28e22006-03-22 09:59:16 +0000385 /* Check for frequency decrease */
386 total_idle_ticks = this_dbs_info->prev_cpu_idle_up;
387 tmp_idle_ticks = total_idle_ticks -
388 this_dbs_info->prev_cpu_idle_down;
389 this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700390
Alexander Clouter08a28e22006-03-22 09:59:16 +0000391 if (tmp_idle_ticks < idle_ticks)
392 idle_ticks = tmp_idle_ticks;
Dave Jonesb9170832005-05-31 19:03:47 -0700393
394 /* Scale idle ticks by 100 and compare with up and down ticks */
395 idle_ticks *= 100;
Alexander Cloutera159b822006-03-22 10:00:18 +0000396 this_dbs_info->down_skip = 0;
Dave Jonesb9170832005-05-31 19:03:47 -0700397
398 freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
399 dbs_tuners_ins.sampling_down_factor;
400 down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
Alexander Clouter2c906b32006-03-22 09:54:10 +0000401 usecs_to_jiffies(freq_down_sampling_rate);
Dave Jonesb9170832005-05-31 19:03:47 -0700402
Dave Jones9c7d2692005-05-31 19:03:49 -0700403 if (idle_ticks > down_idle_ticks) {
Alexander Clouter2c906b32006-03-22 09:54:10 +0000404 /*
405 * if we are already at the lowest speed then break out early
Dave Jonesb9170832005-05-31 19:03:47 -0700406 * or if we 'cannot' reduce the speed as the user might want
Alexander Clouter2c906b32006-03-22 09:54:10 +0000407 * freq_step to be zero
408 */
Alexander Cloutera159b822006-03-22 10:00:18 +0000409 if (this_dbs_info->requested_freq == policy->min
Dave Jonesb9170832005-05-31 19:03:47 -0700410 || dbs_tuners_ins.freq_step == 0)
411 return;
412
413 freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
414
415 /* max freq cannot be less than 100. But who knows.... */
416 if (unlikely(freq_step == 0))
417 freq_step = 5;
418
Alexander Cloutera159b822006-03-22 10:00:18 +0000419 this_dbs_info->requested_freq -= freq_step;
420 if (this_dbs_info->requested_freq < policy->min)
421 this_dbs_info->requested_freq = policy->min;
Dave Jonesb9170832005-05-31 19:03:47 -0700422
Alexander Cloutera159b822006-03-22 10:00:18 +0000423 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
Alexander Clouter2c906b32006-03-22 09:54:10 +0000424 CPUFREQ_RELATION_H);
Dave Jonesb9170832005-05-31 19:03:47 -0700425 return;
426 }
427}
428
David Howellsc4028952006-11-22 14:57:56 +0000429static void do_dbs_timer(struct work_struct *work)
Dave Jonesb9170832005-05-31 19:03:47 -0700430{
431 int i;
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800432 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700433 for_each_online_cpu(i)
434 dbs_check_cpu(i);
435 schedule_delayed_work(&dbs_work,
436 usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800437 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700438}
439
440static inline void dbs_timer_init(void)
441{
Dave Jonesb9170832005-05-31 19:03:47 -0700442 schedule_delayed_work(&dbs_work,
443 usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
444 return;
445}
446
447static inline void dbs_timer_exit(void)
448{
449 cancel_delayed_work(&dbs_work);
450 return;
451}
452
453static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
454 unsigned int event)
455{
456 unsigned int cpu = policy->cpu;
457 struct cpu_dbs_info_s *this_dbs_info;
458 unsigned int j;
Jeff Garzik914f7c32006-10-20 14:31:00 -0700459 int rc;
Dave Jonesb9170832005-05-31 19:03:47 -0700460
461 this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
462
463 switch (event) {
464 case CPUFREQ_GOV_START:
465 if ((!cpu_online(cpu)) ||
466 (!policy->cur))
467 return -EINVAL;
468
469 if (policy->cpuinfo.transition_latency >
470 (TRANSITION_LATENCY_LIMIT * 1000))
471 return -EINVAL;
472 if (this_dbs_info->enable) /* Already enabled */
473 break;
474
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800475 mutex_lock(&dbs_mutex);
Jeff Garzik914f7c32006-10-20 14:31:00 -0700476
477 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
478 if (rc) {
479 mutex_unlock(&dbs_mutex);
480 return rc;
481 }
482
Dave Jonesb9170832005-05-31 19:03:47 -0700483 for_each_cpu_mask(j, policy->cpus) {
484 struct cpu_dbs_info_s *j_dbs_info;
485 j_dbs_info = &per_cpu(cpu_dbs_info, j);
486 j_dbs_info->cur_policy = policy;
487
Alexander Clouter08a28e22006-03-22 09:59:16 +0000488 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(cpu);
Dave Jonesb9170832005-05-31 19:03:47 -0700489 j_dbs_info->prev_cpu_idle_down
490 = j_dbs_info->prev_cpu_idle_up;
491 }
492 this_dbs_info->enable = 1;
Alexander Cloutera159b822006-03-22 10:00:18 +0000493 this_dbs_info->down_skip = 0;
494 this_dbs_info->requested_freq = policy->cur;
Jeff Garzik914f7c32006-10-20 14:31:00 -0700495
Dave Jonesb9170832005-05-31 19:03:47 -0700496 dbs_enable++;
497 /*
498 * Start the timerschedule work, when this governor
499 * is used for first time
500 */
501 if (dbs_enable == 1) {
502 unsigned int latency;
503 /* policy latency is in nS. Convert it to uS first */
Alexander Clouter2c906b32006-03-22 09:54:10 +0000504 latency = policy->cpuinfo.transition_latency / 1000;
505 if (latency == 0)
506 latency = 1;
Dave Jonesb9170832005-05-31 19:03:47 -0700507
Alexander Cloutere8a02572006-03-22 09:56:23 +0000508 def_sampling_rate = 10 * latency *
Dave Jonesb9170832005-05-31 19:03:47 -0700509 DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
Alexander Clouter2c906b32006-03-22 09:54:10 +0000510
511 if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
512 def_sampling_rate = MIN_STAT_SAMPLING_RATE;
513
Dave Jonesb9170832005-05-31 19:03:47 -0700514 dbs_tuners_ins.sampling_rate = def_sampling_rate;
Dave Jonesb9170832005-05-31 19:03:47 -0700515
516 dbs_timer_init();
517 }
518
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800519 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700520 break;
521
522 case CPUFREQ_GOV_STOP:
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800523 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700524 this_dbs_info->enable = 0;
525 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
526 dbs_enable--;
527 /*
528 * Stop the timerschedule work, when this governor
529 * is used for first time
530 */
531 if (dbs_enable == 0)
532 dbs_timer_exit();
533
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800534 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700535
536 break;
537
538 case CPUFREQ_GOV_LIMITS:
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800539 mutex_lock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700540 if (policy->max < this_dbs_info->cur_policy->cur)
541 __cpufreq_driver_target(
542 this_dbs_info->cur_policy,
543 policy->max, CPUFREQ_RELATION_H);
544 else if (policy->min > this_dbs_info->cur_policy->cur)
545 __cpufreq_driver_target(
546 this_dbs_info->cur_policy,
547 policy->min, CPUFREQ_RELATION_L);
akpm@osdl.org3fc54d32006-01-13 15:54:22 -0800548 mutex_unlock(&dbs_mutex);
Dave Jonesb9170832005-05-31 19:03:47 -0700549 break;
550 }
551 return 0;
552}
553
554static struct cpufreq_governor cpufreq_gov_dbs = {
555 .name = "conservative",
556 .governor = cpufreq_governor_dbs,
557 .owner = THIS_MODULE,
558};
559
560static int __init cpufreq_gov_dbs_init(void)
561{
562 return cpufreq_register_governor(&cpufreq_gov_dbs);
563}
564
565static void __exit cpufreq_gov_dbs_exit(void)
566{
567 /* Make sure that the scheduled work is indeed not running */
568 flush_scheduled_work();
569
570 cpufreq_unregister_governor(&cpufreq_gov_dbs);
571}
572
573
574MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>");
575MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
576 "Low Latency Frequency Transition capable processors "
577 "optimised for use in a battery environment");
578MODULE_LICENSE ("GPL");
579
580module_init(cpufreq_gov_dbs_init);
581module_exit(cpufreq_gov_dbs_exit);