1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * drivers/cpufreq/cpufreq_conservative.c
4 *
5 * Copyright (C) 2001 Russell King
6 * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
7 * Jun Nakajima <jun.nakajima@intel.com>
8 * (C) 2009 Alexander Clouter <alex@digriz.org.uk>
9 */
10
11 #include <linux/slab.h>
12 #include "cpufreq_governor.h"
13
14 struct cs_policy_dbs_info {
15 struct policy_dbs_info policy_dbs;
16 unsigned int down_skip;
17 unsigned int requested_freq;
18 };
19
to_dbs_info(struct policy_dbs_info * policy_dbs)20 static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
21 {
22 return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
23 }
24
25 struct cs_dbs_tuners {
26 unsigned int down_threshold;
27 unsigned int freq_step;
28 };
29
30 /* Conservative governor macros */
31 #define DEF_FREQUENCY_UP_THRESHOLD (80)
32 #define DEF_FREQUENCY_DOWN_THRESHOLD (20)
33 #define DEF_FREQUENCY_STEP (5)
34 #define DEF_SAMPLING_DOWN_FACTOR (1)
35 #define MAX_SAMPLING_DOWN_FACTOR (10)
36
get_freq_step(struct cs_dbs_tuners * cs_tuners,struct cpufreq_policy * policy)37 static inline unsigned int get_freq_step(struct cs_dbs_tuners *cs_tuners,
38 struct cpufreq_policy *policy)
39 {
40 unsigned int freq_step = (cs_tuners->freq_step * policy->max) / 100;
41
42 /* max freq cannot be less than 100. But who knows... */
43 if (unlikely(freq_step == 0))
44 freq_step = DEF_FREQUENCY_STEP;
45
46 return freq_step;
47 }
48
49 /*
50 * Every sampling_rate, we check, if current idle time is less than 20%
51 * (default), then we try to increase frequency. Every sampling_rate *
52 * sampling_down_factor, we check, if current idle time is more than 80%
53 * (default), then we try to decrease frequency
54 *
55 * Frequency updates happen at minimum steps of 5% (default) of maximum
56 * frequency
57 */
cs_dbs_update(struct cpufreq_policy * policy)58 static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
59 {
60 struct policy_dbs_info *policy_dbs = policy->governor_data;
61 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
62 unsigned int requested_freq = dbs_info->requested_freq;
63 struct dbs_data *dbs_data = policy_dbs->dbs_data;
64 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
65 unsigned int load = dbs_update(policy);
66 unsigned int freq_step;
67
68 /*
69 * break out if we 'cannot' reduce the speed as the user might
70 * want freq_step to be zero
71 */
72 if (cs_tuners->freq_step == 0)
73 goto out;
74
75 /*
76 * If requested_freq is out of range, it is likely that the limits
77 * changed in the meantime, so fall back to current frequency in that
78 * case.
79 */
80 if (requested_freq > policy->max || requested_freq < policy->min) {
81 requested_freq = policy->cur;
82 dbs_info->requested_freq = requested_freq;
83 }
84
85 freq_step = get_freq_step(cs_tuners, policy);
86
87 /*
88 * Decrease requested_freq one freq_step for each idle period that
89 * we didn't update the frequency.
90 */
91 if (policy_dbs->idle_periods < UINT_MAX) {
92 unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
93
94 if (requested_freq > policy->min + freq_steps)
95 requested_freq -= freq_steps;
96 else
97 requested_freq = policy->min;
98
99 policy_dbs->idle_periods = UINT_MAX;
100 }
101
102 /* Check for frequency increase */
103 if (load > dbs_data->up_threshold) {
104 dbs_info->down_skip = 0;
105
106 /* if we are already at full speed then break out early */
107 if (requested_freq == policy->max)
108 goto out;
109
110 requested_freq += freq_step;
111 if (requested_freq > policy->max)
112 requested_freq = policy->max;
113
114 __cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_H);
115 dbs_info->requested_freq = requested_freq;
116 goto out;
117 }
118
119 /* if sampling_down_factor is active break out early */
120 if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
121 goto out;
122 dbs_info->down_skip = 0;
123
124 /* Check for frequency decrease */
125 if (load < cs_tuners->down_threshold) {
126 /*
127 * if we cannot reduce the frequency anymore, break out early
128 */
129 if (requested_freq == policy->min)
130 goto out;
131
132 if (requested_freq > freq_step)
133 requested_freq -= freq_step;
134 else
135 requested_freq = policy->min;
136
137 __cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_L);
138 dbs_info->requested_freq = requested_freq;
139 }
140
141 out:
142 return dbs_data->sampling_rate;
143 }
144
145 /************************** sysfs interface ************************/
146
store_sampling_down_factor(struct gov_attr_set * attr_set,const char * buf,size_t count)147 static ssize_t store_sampling_down_factor(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 unsigned int input;
152 int ret;
153 ret = sscanf(buf, "%u", &input);
154
155 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
156 return -EINVAL;
157
158 dbs_data->sampling_down_factor = input;
159 return count;
160 }
161
store_up_threshold(struct gov_attr_set * attr_set,const char * buf,size_t count)162 static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
163 const char *buf, size_t count)
164 {
165 struct dbs_data *dbs_data = to_dbs_data(attr_set);
166 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
167 unsigned int input;
168 int ret;
169 ret = sscanf(buf, "%u", &input);
170
171 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
172 return -EINVAL;
173
174 dbs_data->up_threshold = input;
175 return count;
176 }
177
store_down_threshold(struct gov_attr_set * attr_set,const char * buf,size_t count)178 static ssize_t store_down_threshold(struct gov_attr_set *attr_set,
179 const char *buf, size_t count)
180 {
181 struct dbs_data *dbs_data = to_dbs_data(attr_set);
182 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
183 unsigned int input;
184 int ret;
185 ret = sscanf(buf, "%u", &input);
186
187 /* cannot be lower than 1 otherwise freq will not fall */
188 if (ret != 1 || input < 1 || input > 100 ||
189 input >= dbs_data->up_threshold)
190 return -EINVAL;
191
192 cs_tuners->down_threshold = input;
193 return count;
194 }
195
store_ignore_nice_load(struct gov_attr_set * attr_set,const char * buf,size_t count)196 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
197 const char *buf, size_t count)
198 {
199 struct dbs_data *dbs_data = to_dbs_data(attr_set);
200 unsigned int input;
201 int ret;
202
203 ret = sscanf(buf, "%u", &input);
204 if (ret != 1)
205 return -EINVAL;
206
207 if (input > 1)
208 input = 1;
209
210 if (input == dbs_data->ignore_nice_load) /* nothing to do */
211 return count;
212
213 dbs_data->ignore_nice_load = input;
214
215 /* we need to re-evaluate prev_cpu_idle */
216 gov_update_cpu_data(dbs_data);
217
218 return count;
219 }
220
store_freq_step(struct gov_attr_set * attr_set,const char * buf,size_t count)221 static ssize_t store_freq_step(struct gov_attr_set *attr_set, const char *buf,
222 size_t count)
223 {
224 struct dbs_data *dbs_data = to_dbs_data(attr_set);
225 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
226 unsigned int input;
227 int ret;
228 ret = sscanf(buf, "%u", &input);
229
230 if (ret != 1)
231 return -EINVAL;
232
233 if (input > 100)
234 input = 100;
235
236 /*
237 * no need to test here if freq_step is zero as the user might actually
238 * want this, they would be crazy though :)
239 */
240 cs_tuners->freq_step = input;
241 return count;
242 }
243
244 gov_show_one_common(sampling_rate);
245 gov_show_one_common(sampling_down_factor);
246 gov_show_one_common(up_threshold);
247 gov_show_one_common(ignore_nice_load);
248 gov_show_one(cs, down_threshold);
249 gov_show_one(cs, freq_step);
250
251 gov_attr_rw(sampling_rate);
252 gov_attr_rw(sampling_down_factor);
253 gov_attr_rw(up_threshold);
254 gov_attr_rw(ignore_nice_load);
255 gov_attr_rw(down_threshold);
256 gov_attr_rw(freq_step);
257
258 static struct attribute *cs_attributes[] = {
259 &sampling_rate.attr,
260 &sampling_down_factor.attr,
261 &up_threshold.attr,
262 &down_threshold.attr,
263 &ignore_nice_load.attr,
264 &freq_step.attr,
265 NULL
266 };
267
268 /************************** sysfs end ************************/
269
cs_alloc(void)270 static struct policy_dbs_info *cs_alloc(void)
271 {
272 struct cs_policy_dbs_info *dbs_info;
273
274 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
275 return dbs_info ? &dbs_info->policy_dbs : NULL;
276 }
277
cs_free(struct policy_dbs_info * policy_dbs)278 static void cs_free(struct policy_dbs_info *policy_dbs)
279 {
280 kfree(to_dbs_info(policy_dbs));
281 }
282
cs_init(struct dbs_data * dbs_data)283 static int cs_init(struct dbs_data *dbs_data)
284 {
285 struct cs_dbs_tuners *tuners;
286
287 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
288 if (!tuners)
289 return -ENOMEM;
290
291 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
292 tuners->freq_step = DEF_FREQUENCY_STEP;
293 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
294 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
295 dbs_data->ignore_nice_load = 0;
296 dbs_data->tuners = tuners;
297
298 return 0;
299 }
300
cs_exit(struct dbs_data * dbs_data)301 static void cs_exit(struct dbs_data *dbs_data)
302 {
303 kfree(dbs_data->tuners);
304 }
305
cs_start(struct cpufreq_policy * policy)306 static void cs_start(struct cpufreq_policy *policy)
307 {
308 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
309
310 dbs_info->down_skip = 0;
311 dbs_info->requested_freq = policy->cur;
312 }
313
314 static struct dbs_governor cs_governor = {
315 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
316 .kobj_type = { .default_attrs = cs_attributes },
317 .gov_dbs_update = cs_dbs_update,
318 .alloc = cs_alloc,
319 .free = cs_free,
320 .init = cs_init,
321 .exit = cs_exit,
322 .start = cs_start,
323 };
324
325 #define CPU_FREQ_GOV_CONSERVATIVE (&cs_governor.gov)
326
cpufreq_gov_dbs_init(void)327 static int __init cpufreq_gov_dbs_init(void)
328 {
329 return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
330 }
331
cpufreq_gov_dbs_exit(void)332 static void __exit cpufreq_gov_dbs_exit(void)
333 {
334 cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE);
335 }
336
337 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
338 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
339 "Low Latency Frequency Transition capable processors "
340 "optimised for use in a battery environment");
341 MODULE_LICENSE("GPL");
342
343 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
cpufreq_default_governor(void)344 struct cpufreq_governor *cpufreq_default_governor(void)
345 {
346 return CPU_FREQ_GOV_CONSERVATIVE;
347 }
348
349 fs_initcall(cpufreq_gov_dbs_init);
350 #else
351 module_init(cpufreq_gov_dbs_init);
352 #endif
353 module_exit(cpufreq_gov_dbs_exit);
354
