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 dbs_data *dbs_data, 133 const char *buf, size_t count) 134 { 135 unsigned int input; 136 int ret; 137 ret = sscanf(buf, "%u", &input); 138 139 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 140 return -EINVAL; 141 142 dbs_data->sampling_down_factor = input; 143 return count; 144 } 145 146 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf, 147 size_t count) 148 { 149 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 150 unsigned int input; 151 int ret; 152 ret = sscanf(buf, "%u", &input); 153 154 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold) 155 return -EINVAL; 156 157 dbs_data->up_threshold = input; 158 return count; 159 } 160 161 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf, 162 size_t count) 163 { 164 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 165 unsigned int input; 166 int ret; 167 ret = sscanf(buf, "%u", &input); 168 169 /* cannot be lower than 11 otherwise freq will not fall */ 170 if (ret != 1 || input < 11 || input > 100 || 171 input >= dbs_data->up_threshold) 172 return -EINVAL; 173 174 cs_tuners->down_threshold = input; 175 return count; 176 } 177 178 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data, 179 const char *buf, size_t count) 180 { 181 unsigned int input; 182 int ret; 183 184 ret = sscanf(buf, "%u", &input); 185 if (ret != 1) 186 return -EINVAL; 187 188 if (input > 1) 189 input = 1; 190 191 if (input == dbs_data->ignore_nice_load) /* nothing to do */ 192 return count; 193 194 dbs_data->ignore_nice_load = input; 195 196 /* we need to re-evaluate prev_cpu_idle */ 197 gov_update_cpu_data(dbs_data); 198 199 return count; 200 } 201 202 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf, 203 size_t count) 204 { 205 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 206 unsigned int input; 207 int ret; 208 ret = sscanf(buf, "%u", &input); 209 210 if (ret != 1) 211 return -EINVAL; 212 213 if (input > 100) 214 input = 100; 215 216 /* 217 * no need to test here if freq_step is zero as the user might actually 218 * want this, they would be crazy though :) 219 */ 220 cs_tuners->freq_step = input; 221 return count; 222 } 223 224 gov_show_one_common(sampling_rate); 225 gov_show_one_common(sampling_down_factor); 226 gov_show_one_common(up_threshold); 227 gov_show_one_common(ignore_nice_load); 228 gov_show_one_common(min_sampling_rate); 229 gov_show_one(cs, down_threshold); 230 gov_show_one(cs, freq_step); 231 232 gov_attr_rw(sampling_rate); 233 gov_attr_rw(sampling_down_factor); 234 gov_attr_rw(up_threshold); 235 gov_attr_rw(ignore_nice_load); 236 gov_attr_ro(min_sampling_rate); 237 gov_attr_rw(down_threshold); 238 gov_attr_rw(freq_step); 239 240 static struct attribute *cs_attributes[] = { 241 &min_sampling_rate.attr, 242 &sampling_rate.attr, 243 &sampling_down_factor.attr, 244 &up_threshold.attr, 245 &down_threshold.attr, 246 &ignore_nice_load.attr, 247 &freq_step.attr, 248 NULL 249 }; 250 251 /************************** sysfs end ************************/ 252 253 static struct policy_dbs_info *cs_alloc(void) 254 { 255 struct cs_policy_dbs_info *dbs_info; 256 257 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL); 258 return dbs_info ? &dbs_info->policy_dbs : NULL; 259 } 260 261 static void cs_free(struct policy_dbs_info *policy_dbs) 262 { 263 kfree(to_dbs_info(policy_dbs)); 264 } 265 266 static int cs_init(struct dbs_data *dbs_data, bool notify) 267 { 268 struct cs_dbs_tuners *tuners; 269 270 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL); 271 if (!tuners) { 272 pr_err("%s: kzalloc failed\n", __func__); 273 return -ENOMEM; 274 } 275 276 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD; 277 tuners->freq_step = DEF_FREQUENCY_STEP; 278 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD; 279 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; 280 dbs_data->ignore_nice_load = 0; 281 282 dbs_data->tuners = tuners; 283 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO * 284 jiffies_to_usecs(10); 285 286 if (notify) 287 cpufreq_register_notifier(&cs_cpufreq_notifier_block, 288 CPUFREQ_TRANSITION_NOTIFIER); 289 290 return 0; 291 } 292 293 static void cs_exit(struct dbs_data *dbs_data, bool notify) 294 { 295 if (notify) 296 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block, 297 CPUFREQ_TRANSITION_NOTIFIER); 298 299 kfree(dbs_data->tuners); 300 } 301 302 static void cs_start(struct cpufreq_policy *policy) 303 { 304 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data); 305 306 dbs_info->down_skip = 0; 307 dbs_info->requested_freq = policy->cur; 308 } 309 310 static struct dbs_governor cs_dbs_gov = { 311 .gov = { 312 .name = "conservative", 313 .governor = cpufreq_governor_dbs, 314 .max_transition_latency = TRANSITION_LATENCY_LIMIT, 315 .owner = THIS_MODULE, 316 }, 317 .kobj_type = { .default_attrs = cs_attributes }, 318 .gov_dbs_timer = cs_dbs_timer, 319 .alloc = cs_alloc, 320 .free = cs_free, 321 .init = cs_init, 322 .exit = cs_exit, 323 .start = cs_start, 324 }; 325 326 #define CPU_FREQ_GOV_CONSERVATIVE (&cs_dbs_gov.gov) 327 328 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 329 void *data) 330 { 331 struct cpufreq_freqs *freq = data; 332 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu); 333 struct cs_policy_dbs_info *dbs_info; 334 335 if (!policy) 336 return 0; 337 338 /* policy isn't governed by conservative governor */ 339 if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE) 340 return 0; 341 342 dbs_info = to_dbs_info(policy->governor_data); 343 /* 344 * we only care if our internally tracked freq moves outside the 'valid' 345 * ranges of frequency available to us otherwise we do not change it 346 */ 347 if (dbs_info->requested_freq > policy->max 348 || dbs_info->requested_freq < policy->min) 349 dbs_info->requested_freq = freq->new; 350 351 return 0; 352 } 353 354 static int __init cpufreq_gov_dbs_init(void) 355 { 356 return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE); 357 } 358 359 static void __exit cpufreq_gov_dbs_exit(void) 360 { 361 cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE); 362 } 363 364 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>"); 365 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " 366 "Low Latency Frequency Transition capable processors " 367 "optimised for use in a battery environment"); 368 MODULE_LICENSE("GPL"); 369 370 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 371 struct cpufreq_governor *cpufreq_default_governor(void) 372 { 373 return CPU_FREQ_GOV_CONSERVATIVE; 374 } 375 376 fs_initcall(cpufreq_gov_dbs_init); 377 #else 378 module_init(cpufreq_gov_dbs_init); 379 #endif 380 module_exit(cpufreq_gov_dbs_exit); 381