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,
115 CPUFREQ_RELATION_HE);
116 dbs_info->requested_freq = requested_freq;
117 goto out;
118 }
119
120 /* if sampling_down_factor is active break out early */
121 if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
122 goto out;
123 dbs_info->down_skip = 0;
124
125 /* Check for frequency decrease */
126 if (load < cs_tuners->down_threshold) {
127 /*
128 * if we cannot reduce the frequency anymore, break out early
129 */
130 if (requested_freq == policy->min)
131 goto out;
132
133 if (requested_freq > freq_step)
134 requested_freq -= freq_step;
135 else
136 requested_freq = policy->min;
137
138 __cpufreq_driver_target(policy, requested_freq,
139 CPUFREQ_RELATION_LE);
140 dbs_info->requested_freq = requested_freq;
141 }
142
143 out:
144 return dbs_data->sampling_rate;
145 }
146
147 /************************** sysfs interface ************************/
148
sampling_down_factor_store(struct gov_attr_set * attr_set,const char * buf,size_t count)149 static ssize_t sampling_down_factor_store(struct gov_attr_set *attr_set,
150 const char *buf, size_t count)
151 {
152 struct dbs_data *dbs_data = to_dbs_data(attr_set);
153 unsigned int input;
154 int ret;
155 ret = sscanf(buf, "%u", &input);
156
157 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
158 return -EINVAL;
159
160 dbs_data->sampling_down_factor = input;
161 return count;
162 }
163
up_threshold_store(struct gov_attr_set * attr_set,const char * buf,size_t count)164 static ssize_t up_threshold_store(struct gov_attr_set *attr_set,
165 const char *buf, size_t count)
166 {
167 struct dbs_data *dbs_data = to_dbs_data(attr_set);
168 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
169 unsigned int input;
170 int ret;
171 ret = sscanf(buf, "%u", &input);
172
173 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
174 return -EINVAL;
175
176 dbs_data->up_threshold = input;
177 return count;
178 }
179
down_threshold_store(struct gov_attr_set * attr_set,const char * buf,size_t count)180 static ssize_t down_threshold_store(struct gov_attr_set *attr_set,
181 const char *buf, size_t count)
182 {
183 struct dbs_data *dbs_data = to_dbs_data(attr_set);
184 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
185 unsigned int input;
186 int ret;
187 ret = sscanf(buf, "%u", &input);
188
189 /* cannot be lower than 1 otherwise freq will not fall */
190 if (ret != 1 || input < 1 || input > 100 ||
191 input >= dbs_data->up_threshold)
192 return -EINVAL;
193
194 cs_tuners->down_threshold = input;
195 return count;
196 }
197
ignore_nice_load_store(struct gov_attr_set * attr_set,const char * buf,size_t count)198 static ssize_t ignore_nice_load_store(struct gov_attr_set *attr_set,
199 const char *buf, size_t count)
200 {
201 struct dbs_data *dbs_data = to_dbs_data(attr_set);
202 unsigned int input;
203 int ret;
204
205 ret = sscanf(buf, "%u", &input);
206 if (ret != 1)
207 return -EINVAL;
208
209 if (input > 1)
210 input = 1;
211
212 if (input == dbs_data->ignore_nice_load) /* nothing to do */
213 return count;
214
215 dbs_data->ignore_nice_load = input;
216
217 /* we need to re-evaluate prev_cpu_idle */
218 gov_update_cpu_data(dbs_data);
219
220 return count;
221 }
222
freq_step_store(struct gov_attr_set * attr_set,const char * buf,size_t count)223 static ssize_t freq_step_store(struct gov_attr_set *attr_set, const char *buf,
224 size_t count)
225 {
226 struct dbs_data *dbs_data = to_dbs_data(attr_set);
227 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
228 unsigned int input;
229 int ret;
230 ret = sscanf(buf, "%u", &input);
231
232 if (ret != 1)
233 return -EINVAL;
234
235 if (input > 100)
236 input = 100;
237
238 /*
239 * no need to test here if freq_step is zero as the user might actually
240 * want this, they would be crazy though :)
241 */
242 cs_tuners->freq_step = input;
243 return count;
244 }
245
246 gov_show_one_common(sampling_rate);
247 gov_show_one_common(sampling_down_factor);
248 gov_show_one_common(up_threshold);
249 gov_show_one_common(ignore_nice_load);
250 gov_show_one(cs, down_threshold);
251 gov_show_one(cs, freq_step);
252
253 gov_attr_rw(sampling_rate);
254 gov_attr_rw(sampling_down_factor);
255 gov_attr_rw(up_threshold);
256 gov_attr_rw(ignore_nice_load);
257 gov_attr_rw(down_threshold);
258 gov_attr_rw(freq_step);
259
260 static struct attribute *cs_attrs[] = {
261 &sampling_rate.attr,
262 &sampling_down_factor.attr,
263 &up_threshold.attr,
264 &down_threshold.attr,
265 &ignore_nice_load.attr,
266 &freq_step.attr,
267 NULL
268 };
269 ATTRIBUTE_GROUPS(cs);
270
271 /************************** sysfs end ************************/
272
cs_alloc(void)273 static struct policy_dbs_info *cs_alloc(void)
274 {
275 struct cs_policy_dbs_info *dbs_info;
276
277 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
278 return dbs_info ? &dbs_info->policy_dbs : NULL;
279 }
280
cs_free(struct policy_dbs_info * policy_dbs)281 static void cs_free(struct policy_dbs_info *policy_dbs)
282 {
283 kfree(to_dbs_info(policy_dbs));
284 }
285
cs_init(struct dbs_data * dbs_data)286 static int cs_init(struct dbs_data *dbs_data)
287 {
288 struct cs_dbs_tuners *tuners;
289
290 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
291 if (!tuners)
292 return -ENOMEM;
293
294 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
295 tuners->freq_step = DEF_FREQUENCY_STEP;
296 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
297 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
298 dbs_data->ignore_nice_load = 0;
299 dbs_data->tuners = tuners;
300
301 return 0;
302 }
303
cs_exit(struct dbs_data * dbs_data)304 static void cs_exit(struct dbs_data *dbs_data)
305 {
306 kfree(dbs_data->tuners);
307 }
308
cs_start(struct cpufreq_policy * policy)309 static void cs_start(struct cpufreq_policy *policy)
310 {
311 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
312
313 dbs_info->down_skip = 0;
314 dbs_info->requested_freq = policy->cur;
315 }
316
317 static struct dbs_governor cs_governor = {
318 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
319 .kobj_type = { .default_groups = cs_groups },
320 .gov_dbs_update = cs_dbs_update,
321 .alloc = cs_alloc,
322 .free = cs_free,
323 .init = cs_init,
324 .exit = cs_exit,
325 .start = cs_start,
326 };
327
328 #define CPU_FREQ_GOV_CONSERVATIVE (cs_governor.gov)
329
330 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
331 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
332 "Low Latency Frequency Transition capable processors "
333 "optimised for use in a battery environment");
334 MODULE_LICENSE("GPL");
335
336 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
cpufreq_default_governor(void)337 struct cpufreq_governor *cpufreq_default_governor(void)
338 {
339 return &CPU_FREQ_GOV_CONSERVATIVE;
340 }
341 #endif
342
343 cpufreq_governor_init(CPU_FREQ_GOV_CONSERVATIVE);
344 cpufreq_governor_exit(CPU_FREQ_GOV_CONSERVATIVE);
345