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 17 struct cs_policy_dbs_info { 18 struct policy_dbs_info policy_dbs; 19 unsigned int down_skip; 20 unsigned int requested_freq; 21 }; 22 23 static 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 28 struct 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 40 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners, 41 struct cpufreq_policy *policy) 42 { 43 unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100; 44 45 /* max freq cannot be less than 100. But who knows... */ 46 if (unlikely(freq_target == 0)) 47 freq_target = DEF_FREQUENCY_STEP; 48 49 return freq_target; 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 * Any frequency increase takes it to the maximum frequency. Frequency reduction 59 * happens at minimum steps of 5% (default) of maximum frequency 60 */ 61 static unsigned int cs_dbs_timer(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 struct dbs_data *dbs_data = policy_dbs->dbs_data; 66 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 67 unsigned int load = dbs_update(policy); 68 69 /* 70 * break out if we 'cannot' reduce the speed as the user might 71 * want freq_step to be zero 72 */ 73 if (cs_tuners->freq_step == 0) 74 goto out; 75 76 /* Check for frequency increase */ 77 if (load > dbs_data->up_threshold) { 78 dbs_info->down_skip = 0; 79 80 /* if we are already at full speed then break out early */ 81 if (dbs_info->requested_freq == policy->max) 82 goto out; 83 84 dbs_info->requested_freq += get_freq_target(cs_tuners, policy); 85 86 if (dbs_info->requested_freq > policy->max) 87 dbs_info->requested_freq = policy->max; 88 89 __cpufreq_driver_target(policy, dbs_info->requested_freq, 90 CPUFREQ_RELATION_H); 91 goto out; 92 } 93 94 /* if sampling_down_factor is active break out early */ 95 if (++dbs_info->down_skip < dbs_data->sampling_down_factor) 96 goto out; 97 dbs_info->down_skip = 0; 98 99 /* Check for frequency decrease */ 100 if (load < cs_tuners->down_threshold) { 101 unsigned int freq_target; 102 /* 103 * if we cannot reduce the frequency anymore, break out early 104 */ 105 if (policy->cur == policy->min) 106 goto out; 107 108 freq_target = get_freq_target(cs_tuners, policy); 109 if (dbs_info->requested_freq > freq_target) 110 dbs_info->requested_freq -= freq_target; 111 else 112 dbs_info->requested_freq = policy->min; 113 114 __cpufreq_driver_target(policy, dbs_info->requested_freq, 115 CPUFREQ_RELATION_L); 116 } 117 118 out: 119 return dbs_data->sampling_rate; 120 } 121 122 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 123 void *data); 124 125 static struct notifier_block cs_cpufreq_notifier_block = { 126 .notifier_call = dbs_cpufreq_notifier, 127 }; 128 129 /************************** sysfs interface ************************/ 130 static struct dbs_governor cs_dbs_gov; 131 132 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set, 133 const char *buf, size_t count) 134 { 135 struct dbs_data *dbs_data = to_dbs_data(attr_set); 136 unsigned int input; 137 int ret; 138 ret = sscanf(buf, "%u", &input); 139 140 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 141 return -EINVAL; 142 143 dbs_data->sampling_down_factor = input; 144 return count; 145 } 146 147 static ssize_t store_up_threshold(struct gov_attr_set *attr_set, 148 const char *buf, size_t count) 149 { 150 struct dbs_data *dbs_data = to_dbs_data(attr_set); 151 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 152 unsigned int input; 153 int ret; 154 ret = sscanf(buf, "%u", &input); 155 156 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold) 157 return -EINVAL; 158 159 dbs_data->up_threshold = input; 160 return count; 161 } 162 163 static ssize_t store_down_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 /* cannot be lower than 11 otherwise freq will not fall */ 173 if (ret != 1 || input < 11 || input > 100 || 174 input >= dbs_data->up_threshold) 175 return -EINVAL; 176 177 cs_tuners->down_threshold = input; 178 return count; 179 } 180 181 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set, 182 const char *buf, size_t count) 183 { 184 struct dbs_data *dbs_data = to_dbs_data(attr_set); 185 unsigned int input; 186 int ret; 187 188 ret = sscanf(buf, "%u", &input); 189 if (ret != 1) 190 return -EINVAL; 191 192 if (input > 1) 193 input = 1; 194 195 if (input == dbs_data->ignore_nice_load) /* nothing to do */ 196 return count; 197 198 dbs_data->ignore_nice_load = input; 199 200 /* we need to re-evaluate prev_cpu_idle */ 201 gov_update_cpu_data(dbs_data); 202 203 return count; 204 } 205 206 static ssize_t store_freq_step(struct gov_attr_set *attr_set, const char *buf, 207 size_t count) 208 { 209 struct dbs_data *dbs_data = to_dbs_data(attr_set); 210 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 211 unsigned int input; 212 int ret; 213 ret = sscanf(buf, "%u", &input); 214 215 if (ret != 1) 216 return -EINVAL; 217 218 if (input > 100) 219 input = 100; 220 221 /* 222 * no need to test here if freq_step is zero as the user might actually 223 * want this, they would be crazy though :) 224 */ 225 cs_tuners->freq_step = input; 226 return count; 227 } 228 229 gov_show_one_common(sampling_rate); 230 gov_show_one_common(sampling_down_factor); 231 gov_show_one_common(up_threshold); 232 gov_show_one_common(ignore_nice_load); 233 gov_show_one_common(min_sampling_rate); 234 gov_show_one(cs, down_threshold); 235 gov_show_one(cs, freq_step); 236 237 gov_attr_rw(sampling_rate); 238 gov_attr_rw(sampling_down_factor); 239 gov_attr_rw(up_threshold); 240 gov_attr_rw(ignore_nice_load); 241 gov_attr_ro(min_sampling_rate); 242 gov_attr_rw(down_threshold); 243 gov_attr_rw(freq_step); 244 245 static struct attribute *cs_attributes[] = { 246 &min_sampling_rate.attr, 247 &sampling_rate.attr, 248 &sampling_down_factor.attr, 249 &up_threshold.attr, 250 &down_threshold.attr, 251 &ignore_nice_load.attr, 252 &freq_step.attr, 253 NULL 254 }; 255 256 /************************** sysfs end ************************/ 257 258 static struct policy_dbs_info *cs_alloc(void) 259 { 260 struct cs_policy_dbs_info *dbs_info; 261 262 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL); 263 return dbs_info ? &dbs_info->policy_dbs : NULL; 264 } 265 266 static void cs_free(struct policy_dbs_info *policy_dbs) 267 { 268 kfree(to_dbs_info(policy_dbs)); 269 } 270 271 static int cs_init(struct dbs_data *dbs_data, bool notify) 272 { 273 struct cs_dbs_tuners *tuners; 274 275 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL); 276 if (!tuners) { 277 pr_err("%s: kzalloc failed\n", __func__); 278 return -ENOMEM; 279 } 280 281 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD; 282 tuners->freq_step = DEF_FREQUENCY_STEP; 283 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD; 284 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; 285 dbs_data->ignore_nice_load = 0; 286 287 dbs_data->tuners = tuners; 288 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO * 289 jiffies_to_usecs(10); 290 291 if (notify) 292 cpufreq_register_notifier(&cs_cpufreq_notifier_block, 293 CPUFREQ_TRANSITION_NOTIFIER); 294 295 return 0; 296 } 297 298 static void cs_exit(struct dbs_data *dbs_data, bool notify) 299 { 300 if (notify) 301 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block, 302 CPUFREQ_TRANSITION_NOTIFIER); 303 304 kfree(dbs_data->tuners); 305 } 306 307 static void cs_start(struct cpufreq_policy *policy) 308 { 309 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data); 310 311 dbs_info->down_skip = 0; 312 dbs_info->requested_freq = policy->cur; 313 } 314 315 static struct dbs_governor cs_dbs_gov = { 316 .gov = { 317 .name = "conservative", 318 .governor = cpufreq_governor_dbs, 319 .max_transition_latency = TRANSITION_LATENCY_LIMIT, 320 .owner = THIS_MODULE, 321 }, 322 .kobj_type = { .default_attrs = cs_attributes }, 323 .gov_dbs_timer = cs_dbs_timer, 324 .alloc = cs_alloc, 325 .free = cs_free, 326 .init = cs_init, 327 .exit = cs_exit, 328 .start = cs_start, 329 }; 330 331 #define CPU_FREQ_GOV_CONSERVATIVE (&cs_dbs_gov.gov) 332 333 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 334 void *data) 335 { 336 struct cpufreq_freqs *freq = data; 337 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu); 338 struct cs_policy_dbs_info *dbs_info; 339 340 if (!policy) 341 return 0; 342 343 /* policy isn't governed by conservative governor */ 344 if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE) 345 return 0; 346 347 dbs_info = to_dbs_info(policy->governor_data); 348 /* 349 * we only care if our internally tracked freq moves outside the 'valid' 350 * ranges of frequency available to us otherwise we do not change it 351 */ 352 if (dbs_info->requested_freq > policy->max 353 || dbs_info->requested_freq < policy->min) 354 dbs_info->requested_freq = freq->new; 355 356 return 0; 357 } 358 359 static int __init cpufreq_gov_dbs_init(void) 360 { 361 return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE); 362 } 363 364 static void __exit cpufreq_gov_dbs_exit(void) 365 { 366 cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE); 367 } 368 369 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>"); 370 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " 371 "Low Latency Frequency Transition capable processors " 372 "optimised for use in a battery environment"); 373 MODULE_LICENSE("GPL"); 374 375 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 376 struct cpufreq_governor *cpufreq_default_governor(void) 377 { 378 return CPU_FREQ_GOV_CONSERVATIVE; 379 } 380 381 fs_initcall(cpufreq_gov_dbs_init); 382 #else 383 module_init(cpufreq_gov_dbs_init); 384 #endif 385 module_exit(cpufreq_gov_dbs_exit); 386