1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/cpufreq/cpufreq_ondemand.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 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/cpu.h>
13#include <linux/percpu-defs.h>
14#include <linux/slab.h>
15#include <linux/tick.h>
16#include <linux/sched/cpufreq.h>
17
18#include "cpufreq_ondemand.h"
19
20/* On-demand governor macros */
21#define DEF_FREQUENCY_UP_THRESHOLD (80)
22#define DEF_SAMPLING_DOWN_FACTOR (1)
23#define MAX_SAMPLING_DOWN_FACTOR (100000)
24#define MICRO_FREQUENCY_UP_THRESHOLD (95)
25#define MIN_FREQUENCY_UP_THRESHOLD (1)
26#define MAX_FREQUENCY_UP_THRESHOLD (100)
27
28static struct od_ops od_ops;
29
30static unsigned int default_powersave_bias;
31
32/*
33 * Not all CPUs want IO time to be accounted as busy; this depends on how
34 * efficient idling at a higher frequency/voltage is.
35 * Pavel Machek says this is not so for various generations of AMD and old
36 * Intel systems.
37 * Mike Chan (android.com) claims this is also not true for ARM.
38 * Because of this, whitelist specific known (series) of CPUs by default, and
39 * leave all others up to the user.
40 */
41static int should_io_be_busy(void)
42{
43#if defined(CONFIG_X86)
44 /*
45 * For Intel, Core 2 (model 15) and later have an efficient idle.
46 */
47 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
48 boot_cpu_data.x86 == 6 &&
49 boot_cpu_data.x86_model >= 15)
50 return 1;
51#endif
52 return 0;
53}
54
55/*
56 * Find right freq to be set now with powersave_bias on.
57 * Returns the freq_hi to be used right now and will set freq_hi_delay_us,
58 * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
59 */
60static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
61 unsigned int freq_next, unsigned int relation)
62{
63 unsigned int freq_req, freq_reduc, freq_avg;
64 unsigned int freq_hi, freq_lo;
65 unsigned int index;
66 unsigned int delay_hi_us;
67 struct policy_dbs_info *policy_dbs = policy->governor_data;
68 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
69 struct dbs_data *dbs_data = policy_dbs->dbs_data;
70 struct od_dbs_tuners *od_tuners = dbs_data->tuners;
71 struct cpufreq_frequency_table *freq_table = policy->freq_table;
72
73 if (!freq_table) {
74 dbs_info->freq_lo = 0;
75 dbs_info->freq_lo_delay_us = 0;
76 return freq_next;
77 }
78
79 index = cpufreq_frequency_table_target(policy, target_freq: freq_next, relation);
80 freq_req = freq_table[index].frequency;
81 freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
82 freq_avg = freq_req - freq_reduc;
83
84 /* Find freq bounds for freq_avg in freq_table */
85 index = cpufreq_table_find_index_h(policy, target_freq: freq_avg,
86 efficiencies: relation & CPUFREQ_RELATION_E);
87 freq_lo = freq_table[index].frequency;
88 index = cpufreq_table_find_index_l(policy, target_freq: freq_avg,
89 efficiencies: relation & CPUFREQ_RELATION_E);
90 freq_hi = freq_table[index].frequency;
91
92 /* Find out how long we have to be in hi and lo freqs */
93 if (freq_hi == freq_lo) {
94 dbs_info->freq_lo = 0;
95 dbs_info->freq_lo_delay_us = 0;
96 return freq_lo;
97 }
98 delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
99 delay_hi_us += (freq_hi - freq_lo) / 2;
100 delay_hi_us /= freq_hi - freq_lo;
101 dbs_info->freq_hi_delay_us = delay_hi_us;
102 dbs_info->freq_lo = freq_lo;
103 dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
104 return freq_hi;
105}
106
107static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
108{
109 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs: policy->governor_data);
110
111 dbs_info->freq_lo = 0;
112}
113
114static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
115{
116 struct policy_dbs_info *policy_dbs = policy->governor_data;
117 struct dbs_data *dbs_data = policy_dbs->dbs_data;
118 struct od_dbs_tuners *od_tuners = dbs_data->tuners;
119
120 if (od_tuners->powersave_bias)
121 freq = od_ops.powersave_bias_target(policy, freq,
122 CPUFREQ_RELATION_HE);
123 else if (policy->cur == policy->max)
124 return;
125
126 __cpufreq_driver_target(policy, target_freq: freq, relation: od_tuners->powersave_bias ?
127 CPUFREQ_RELATION_LE : CPUFREQ_RELATION_HE);
128}
129
130/*
131 * Every sampling_rate, we check, if current idle time is less than 20%
132 * (default), then we try to increase frequency. Else, we adjust the frequency
133 * proportional to load.
134 */
135static void od_update(struct cpufreq_policy *policy)
136{
137 struct policy_dbs_info *policy_dbs = policy->governor_data;
138 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
139 struct dbs_data *dbs_data = policy_dbs->dbs_data;
140 struct od_dbs_tuners *od_tuners = dbs_data->tuners;
141 unsigned int load = dbs_update(policy);
142
143 dbs_info->freq_lo = 0;
144
145 /* Check for frequency increase */
146 if (load > dbs_data->up_threshold) {
147 /* If switching to max speed, apply sampling_down_factor */
148 if (policy->cur < policy->max)
149 policy_dbs->rate_mult = dbs_data->sampling_down_factor;
150 dbs_freq_increase(policy, freq: policy->max);
151 } else {
152 /* Calculate the next frequency proportional to load */
153 unsigned int freq_next, min_f, max_f;
154
155 min_f = policy->cpuinfo.min_freq;
156 max_f = policy->cpuinfo.max_freq;
157 freq_next = min_f + load * (max_f - min_f) / 100;
158
159 /* No longer fully busy, reset rate_mult */
160 policy_dbs->rate_mult = 1;
161
162 if (od_tuners->powersave_bias)
163 freq_next = od_ops.powersave_bias_target(policy,
164 freq_next,
165 CPUFREQ_RELATION_LE);
166
167 __cpufreq_driver_target(policy, target_freq: freq_next, CPUFREQ_RELATION_CE);
168 }
169}
170
171static unsigned int od_dbs_update(struct cpufreq_policy *policy)
172{
173 struct policy_dbs_info *policy_dbs = policy->governor_data;
174 struct dbs_data *dbs_data = policy_dbs->dbs_data;
175 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
176 int sample_type = dbs_info->sample_type;
177
178 /* Common NORMAL_SAMPLE setup */
179 dbs_info->sample_type = OD_NORMAL_SAMPLE;
180 /*
181 * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
182 * it then.
183 */
184 if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
185 __cpufreq_driver_target(policy, target_freq: dbs_info->freq_lo,
186 CPUFREQ_RELATION_HE);
187 return dbs_info->freq_lo_delay_us;
188 }
189
190 od_update(policy);
191
192 if (dbs_info->freq_lo) {
193 /* Setup SUB_SAMPLE */
194 dbs_info->sample_type = OD_SUB_SAMPLE;
195 return dbs_info->freq_hi_delay_us;
196 }
197
198 return dbs_data->sampling_rate * policy_dbs->rate_mult;
199}
200
201/************************** sysfs interface ************************/
202static struct dbs_governor od_dbs_gov;
203
204static ssize_t io_is_busy_store(struct gov_attr_set *attr_set, const char *buf,
205 size_t count)
206{
207 struct dbs_data *dbs_data = to_dbs_data(attr_set);
208 unsigned int input;
209 int ret;
210
211 ret = sscanf(buf, "%u", &input);
212 if (ret != 1)
213 return -EINVAL;
214 dbs_data->io_is_busy = !!input;
215
216 /* we need to re-evaluate prev_cpu_idle */
217 gov_update_cpu_data(dbs_data);
218
219 return count;
220}
221
222static ssize_t up_threshold_store(struct gov_attr_set *attr_set,
223 const char *buf, size_t count)
224{
225 struct dbs_data *dbs_data = to_dbs_data(attr_set);
226 unsigned int input;
227 int ret;
228 ret = sscanf(buf, "%u", &input);
229
230 if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
231 input < MIN_FREQUENCY_UP_THRESHOLD) {
232 return -EINVAL;
233 }
234
235 dbs_data->up_threshold = input;
236 return count;
237}
238
239static ssize_t sampling_down_factor_store(struct gov_attr_set *attr_set,
240 const char *buf, size_t count)
241{
242 struct dbs_data *dbs_data = to_dbs_data(attr_set);
243 struct policy_dbs_info *policy_dbs;
244 unsigned int input;
245 int ret;
246 ret = sscanf(buf, "%u", &input);
247
248 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
249 return -EINVAL;
250
251 dbs_data->sampling_down_factor = input;
252
253 /* Reset down sampling multiplier in case it was active */
254 list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
255 /*
256 * Doing this without locking might lead to using different
257 * rate_mult values in od_update() and od_dbs_update().
258 */
259 mutex_lock(&policy_dbs->update_mutex);
260 policy_dbs->rate_mult = 1;
261 mutex_unlock(lock: &policy_dbs->update_mutex);
262 }
263
264 return count;
265}
266
267static ssize_t ignore_nice_load_store(struct gov_attr_set *attr_set,
268 const char *buf, size_t count)
269{
270 struct dbs_data *dbs_data = to_dbs_data(attr_set);
271 unsigned int input;
272 int ret;
273
274 ret = sscanf(buf, "%u", &input);
275 if (ret != 1)
276 return -EINVAL;
277
278 if (input > 1)
279 input = 1;
280
281 if (input == dbs_data->ignore_nice_load) { /* nothing to do */
282 return count;
283 }
284 dbs_data->ignore_nice_load = input;
285
286 /* we need to re-evaluate prev_cpu_idle */
287 gov_update_cpu_data(dbs_data);
288
289 return count;
290}
291
292static ssize_t powersave_bias_store(struct gov_attr_set *attr_set,
293 const char *buf, size_t count)
294{
295 struct dbs_data *dbs_data = to_dbs_data(attr_set);
296 struct od_dbs_tuners *od_tuners = dbs_data->tuners;
297 struct policy_dbs_info *policy_dbs;
298 unsigned int input;
299 int ret;
300 ret = sscanf(buf, "%u", &input);
301
302 if (ret != 1)
303 return -EINVAL;
304
305 if (input > 1000)
306 input = 1000;
307
308 od_tuners->powersave_bias = input;
309
310 list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
311 ondemand_powersave_bias_init(policy: policy_dbs->policy);
312
313 return count;
314}
315
316gov_show_one_common(sampling_rate);
317gov_show_one_common(up_threshold);
318gov_show_one_common(sampling_down_factor);
319gov_show_one_common(ignore_nice_load);
320gov_show_one_common(io_is_busy);
321gov_show_one(od, powersave_bias);
322
323gov_attr_rw(sampling_rate);
324gov_attr_rw(io_is_busy);
325gov_attr_rw(up_threshold);
326gov_attr_rw(sampling_down_factor);
327gov_attr_rw(ignore_nice_load);
328gov_attr_rw(powersave_bias);
329
330static struct attribute *od_attrs[] = {
331 &sampling_rate.attr,
332 &up_threshold.attr,
333 &sampling_down_factor.attr,
334 &ignore_nice_load.attr,
335 &powersave_bias.attr,
336 &io_is_busy.attr,
337 NULL
338};
339ATTRIBUTE_GROUPS(od);
340
341/************************** sysfs end ************************/
342
343static struct policy_dbs_info *od_alloc(void)
344{
345 struct od_policy_dbs_info *dbs_info;
346
347 dbs_info = kzalloc(size: sizeof(*dbs_info), GFP_KERNEL);
348 return dbs_info ? &dbs_info->policy_dbs : NULL;
349}
350
351static void od_free(struct policy_dbs_info *policy_dbs)
352{
353 kfree(objp: to_dbs_info(policy_dbs));
354}
355
356static int od_init(struct dbs_data *dbs_data)
357{
358 struct od_dbs_tuners *tuners;
359 u64 idle_time;
360 int cpu;
361
362 tuners = kzalloc(size: sizeof(*tuners), GFP_KERNEL);
363 if (!tuners)
364 return -ENOMEM;
365
366 cpu = get_cpu();
367 idle_time = get_cpu_idle_time_us(cpu, NULL);
368 put_cpu();
369 if (idle_time != -1ULL) {
370 /* Idle micro accounting is supported. Use finer thresholds */
371 dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
372 } else {
373 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
374 }
375
376 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
377 dbs_data->ignore_nice_load = 0;
378 tuners->powersave_bias = default_powersave_bias;
379 dbs_data->io_is_busy = should_io_be_busy();
380
381 dbs_data->tuners = tuners;
382 return 0;
383}
384
385static void od_exit(struct dbs_data *dbs_data)
386{
387 kfree(objp: dbs_data->tuners);
388}
389
390static void od_start(struct cpufreq_policy *policy)
391{
392 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs: policy->governor_data);
393
394 dbs_info->sample_type = OD_NORMAL_SAMPLE;
395 ondemand_powersave_bias_init(policy);
396}
397
398static struct od_ops od_ops = {
399 .powersave_bias_target = generic_powersave_bias_target,
400};
401
402static struct dbs_governor od_dbs_gov = {
403 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
404 .kobj_type = { .default_groups = od_groups },
405 .gov_dbs_update = od_dbs_update,
406 .alloc = od_alloc,
407 .free = od_free,
408 .init = od_init,
409 .exit = od_exit,
410 .start = od_start,
411};
412
413#define CPU_FREQ_GOV_ONDEMAND (od_dbs_gov.gov)
414
415static void od_set_powersave_bias(unsigned int powersave_bias)
416{
417 unsigned int cpu;
418 cpumask_var_t done;
419
420 if (!alloc_cpumask_var(mask: &done, GFP_KERNEL))
421 return;
422
423 default_powersave_bias = powersave_bias;
424 cpumask_clear(dstp: done);
425
426 cpus_read_lock();
427 for_each_online_cpu(cpu) {
428 struct cpufreq_policy *policy;
429 struct policy_dbs_info *policy_dbs;
430 struct dbs_data *dbs_data;
431 struct od_dbs_tuners *od_tuners;
432
433 if (cpumask_test_cpu(cpu, cpumask: done))
434 continue;
435
436 policy = cpufreq_cpu_get_raw(cpu);
437 if (!policy || policy->governor != &CPU_FREQ_GOV_ONDEMAND)
438 continue;
439
440 policy_dbs = policy->governor_data;
441 if (!policy_dbs)
442 continue;
443
444 cpumask_or(dstp: done, src1p: done, src2p: policy->cpus);
445
446 dbs_data = policy_dbs->dbs_data;
447 od_tuners = dbs_data->tuners;
448 od_tuners->powersave_bias = default_powersave_bias;
449 }
450 cpus_read_unlock();
451
452 free_cpumask_var(mask: done);
453}
454
455void od_register_powersave_bias_handler(unsigned int (*f)
456 (struct cpufreq_policy *, unsigned int, unsigned int),
457 unsigned int powersave_bias)
458{
459 od_ops.powersave_bias_target = f;
460 od_set_powersave_bias(powersave_bias);
461}
462EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
463
464void od_unregister_powersave_bias_handler(void)
465{
466 od_ops.powersave_bias_target = generic_powersave_bias_target;
467 od_set_powersave_bias(powersave_bias: 0);
468}
469EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
470
471MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
472MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
473MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
474 "Low Latency Frequency Transition capable processors");
475MODULE_LICENSE("GPL");
476
477#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
478struct cpufreq_governor *cpufreq_default_governor(void)
479{
480 return &CPU_FREQ_GOV_ONDEMAND;
481}
482#endif
483
484cpufreq_governor_init(CPU_FREQ_GOV_ONDEMAND);
485cpufreq_governor_exit(CPU_FREQ_GOV_ONDEMAND);
486

source code of linux/drivers/cpufreq/cpufreq_ondemand.c