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 MICRO_FREQUENCY_MIN_SAMPLE_RATE		(10000)
26 #define MIN_FREQUENCY_UP_THRESHOLD		(1)
27 #define MAX_FREQUENCY_UP_THRESHOLD		(100)
28 
29 static struct od_ops od_ops;
30 
31 static unsigned int default_powersave_bias;
32 
33 /*
34  * Not all CPUs want IO time to be accounted as busy; this depends on how
35  * efficient idling at a higher frequency/voltage is.
36  * Pavel Machek says this is not so for various generations of AMD and old
37  * Intel systems.
38  * Mike Chan (android.com) claims this is also not true for ARM.
39  * Because of this, whitelist specific known (series) of CPUs by default, and
40  * leave all others up to the user.
41  */
should_io_be_busy(void)42 static int should_io_be_busy(void)
43 {
44 #if defined(CONFIG_X86)
45 	/*
46 	 * For Intel, Core 2 (model 15) and later have an efficient idle.
47 	 */
48 	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
49 			boot_cpu_data.x86 == 6 &&
50 			boot_cpu_data.x86_model >= 15)
51 		return 1;
52 #endif
53 	return 0;
54 }
55 
56 /*
57  * Find right freq to be set now with powersave_bias on.
58  * Returns the freq_hi to be used right now and will set freq_hi_delay_us,
59  * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
60  */
generic_powersave_bias_target(struct cpufreq_policy * policy,unsigned int freq_next,unsigned int relation)61 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
62 		unsigned int freq_next, unsigned int relation)
63 {
64 	unsigned int freq_req, freq_reduc, freq_avg;
65 	unsigned int freq_hi, freq_lo;
66 	unsigned int index;
67 	unsigned int delay_hi_us;
68 	struct policy_dbs_info *policy_dbs = policy->governor_data;
69 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
70 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
71 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
72 	struct cpufreq_frequency_table *freq_table = policy->freq_table;
73 
74 	if (!freq_table) {
75 		dbs_info->freq_lo = 0;
76 		dbs_info->freq_lo_delay_us = 0;
77 		return freq_next;
78 	}
79 
80 	index = cpufreq_frequency_table_target(policy, freq_next, relation);
81 	freq_req = freq_table[index].frequency;
82 	freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
83 	freq_avg = freq_req - freq_reduc;
84 
85 	/* Find freq bounds for freq_avg in freq_table */
86 	index = cpufreq_table_find_index_h(policy, freq_avg,
87 					   relation & CPUFREQ_RELATION_E);
88 	freq_lo = freq_table[index].frequency;
89 	index = cpufreq_table_find_index_l(policy, freq_avg,
90 					   relation & CPUFREQ_RELATION_E);
91 	freq_hi = freq_table[index].frequency;
92 
93 	/* Find out how long we have to be in hi and lo freqs */
94 	if (freq_hi == freq_lo) {
95 		dbs_info->freq_lo = 0;
96 		dbs_info->freq_lo_delay_us = 0;
97 		return freq_lo;
98 	}
99 	delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
100 	delay_hi_us += (freq_hi - freq_lo) / 2;
101 	delay_hi_us /= freq_hi - freq_lo;
102 	dbs_info->freq_hi_delay_us = delay_hi_us;
103 	dbs_info->freq_lo = freq_lo;
104 	dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
105 	return freq_hi;
106 }
107 
ondemand_powersave_bias_init(struct cpufreq_policy * policy)108 static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
109 {
110 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
111 
112 	dbs_info->freq_lo = 0;
113 }
114 
dbs_freq_increase(struct cpufreq_policy * policy,unsigned int freq)115 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
116 {
117 	struct policy_dbs_info *policy_dbs = policy->governor_data;
118 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
119 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
120 
121 	if (od_tuners->powersave_bias)
122 		freq = od_ops.powersave_bias_target(policy, freq,
123 						    CPUFREQ_RELATION_HE);
124 	else if (policy->cur == policy->max)
125 		return;
126 
127 	__cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
128 			CPUFREQ_RELATION_LE : CPUFREQ_RELATION_HE);
129 }
130 
131 /*
132  * Every sampling_rate, we check, if current idle time is less than 20%
133  * (default), then we try to increase frequency. Else, we adjust the frequency
134  * proportional to load.
135  */
od_update(struct cpufreq_policy * policy)136 static void od_update(struct cpufreq_policy *policy)
137 {
138 	struct policy_dbs_info *policy_dbs = policy->governor_data;
139 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
140 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
141 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
142 	unsigned int load = dbs_update(policy);
143 
144 	dbs_info->freq_lo = 0;
145 
146 	/* Check for frequency increase */
147 	if (load > dbs_data->up_threshold) {
148 		/* If switching to max speed, apply sampling_down_factor */
149 		if (policy->cur < policy->max)
150 			policy_dbs->rate_mult = dbs_data->sampling_down_factor;
151 		dbs_freq_increase(policy, policy->max);
152 	} else {
153 		/* Calculate the next frequency proportional to load */
154 		unsigned int freq_next, min_f, max_f;
155 
156 		min_f = policy->cpuinfo.min_freq;
157 		max_f = policy->cpuinfo.max_freq;
158 		freq_next = min_f + load * (max_f - min_f) / 100;
159 
160 		/* No longer fully busy, reset rate_mult */
161 		policy_dbs->rate_mult = 1;
162 
163 		if (od_tuners->powersave_bias)
164 			freq_next = od_ops.powersave_bias_target(policy,
165 								 freq_next,
166 								 CPUFREQ_RELATION_LE);
167 
168 		__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_CE);
169 	}
170 }
171 
od_dbs_update(struct cpufreq_policy * policy)172 static unsigned int od_dbs_update(struct cpufreq_policy *policy)
173 {
174 	struct policy_dbs_info *policy_dbs = policy->governor_data;
175 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
176 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
177 	int sample_type = dbs_info->sample_type;
178 
179 	/* Common NORMAL_SAMPLE setup */
180 	dbs_info->sample_type = OD_NORMAL_SAMPLE;
181 	/*
182 	 * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
183 	 * it then.
184 	 */
185 	if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
186 		__cpufreq_driver_target(policy, dbs_info->freq_lo,
187 					CPUFREQ_RELATION_HE);
188 		return dbs_info->freq_lo_delay_us;
189 	}
190 
191 	od_update(policy);
192 
193 	if (dbs_info->freq_lo) {
194 		/* Setup SUB_SAMPLE */
195 		dbs_info->sample_type = OD_SUB_SAMPLE;
196 		return dbs_info->freq_hi_delay_us;
197 	}
198 
199 	return dbs_data->sampling_rate * policy_dbs->rate_mult;
200 }
201 
202 /************************** sysfs interface ************************/
203 static struct dbs_governor od_dbs_gov;
204 
io_is_busy_store(struct gov_attr_set * attr_set,const char * buf,size_t count)205 static ssize_t io_is_busy_store(struct gov_attr_set *attr_set, const char *buf,
206 				size_t count)
207 {
208 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
209 	unsigned int input;
210 	int ret;
211 
212 	ret = sscanf(buf, "%u", &input);
213 	if (ret != 1)
214 		return -EINVAL;
215 	dbs_data->io_is_busy = !!input;
216 
217 	/* we need to re-evaluate prev_cpu_idle */
218 	gov_update_cpu_data(dbs_data);
219 
220 	return count;
221 }
222 
up_threshold_store(struct gov_attr_set * attr_set,const char * buf,size_t count)223 static ssize_t up_threshold_store(struct gov_attr_set *attr_set,
224 				  const char *buf, size_t count)
225 {
226 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
227 	unsigned int input;
228 	int ret;
229 	ret = sscanf(buf, "%u", &input);
230 
231 	if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
232 			input < MIN_FREQUENCY_UP_THRESHOLD) {
233 		return -EINVAL;
234 	}
235 
236 	dbs_data->up_threshold = input;
237 	return count;
238 }
239 
sampling_down_factor_store(struct gov_attr_set * attr_set,const char * buf,size_t count)240 static ssize_t sampling_down_factor_store(struct gov_attr_set *attr_set,
241 					  const char *buf, size_t count)
242 {
243 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
244 	struct policy_dbs_info *policy_dbs;
245 	unsigned int input;
246 	int ret;
247 	ret = sscanf(buf, "%u", &input);
248 
249 	if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
250 		return -EINVAL;
251 
252 	dbs_data->sampling_down_factor = input;
253 
254 	/* Reset down sampling multiplier in case it was active */
255 	list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
256 		/*
257 		 * Doing this without locking might lead to using different
258 		 * rate_mult values in od_update() and od_dbs_update().
259 		 */
260 		mutex_lock(&policy_dbs->update_mutex);
261 		policy_dbs->rate_mult = 1;
262 		mutex_unlock(&policy_dbs->update_mutex);
263 	}
264 
265 	return count;
266 }
267 
ignore_nice_load_store(struct gov_attr_set * attr_set,const char * buf,size_t count)268 static ssize_t ignore_nice_load_store(struct gov_attr_set *attr_set,
269 				      const char *buf, size_t count)
270 {
271 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
272 	unsigned int input;
273 	int ret;
274 
275 	ret = sscanf(buf, "%u", &input);
276 	if (ret != 1)
277 		return -EINVAL;
278 
279 	if (input > 1)
280 		input = 1;
281 
282 	if (input == dbs_data->ignore_nice_load) { /* nothing to do */
283 		return count;
284 	}
285 	dbs_data->ignore_nice_load = input;
286 
287 	/* we need to re-evaluate prev_cpu_idle */
288 	gov_update_cpu_data(dbs_data);
289 
290 	return count;
291 }
292 
powersave_bias_store(struct gov_attr_set * attr_set,const char * buf,size_t count)293 static ssize_t powersave_bias_store(struct gov_attr_set *attr_set,
294 				    const char *buf, size_t count)
295 {
296 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
297 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
298 	struct policy_dbs_info *policy_dbs;
299 	unsigned int input;
300 	int ret;
301 	ret = sscanf(buf, "%u", &input);
302 
303 	if (ret != 1)
304 		return -EINVAL;
305 
306 	if (input > 1000)
307 		input = 1000;
308 
309 	od_tuners->powersave_bias = input;
310 
311 	list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
312 		ondemand_powersave_bias_init(policy_dbs->policy);
313 
314 	return count;
315 }
316 
317 gov_show_one_common(sampling_rate);
318 gov_show_one_common(up_threshold);
319 gov_show_one_common(sampling_down_factor);
320 gov_show_one_common(ignore_nice_load);
321 gov_show_one_common(io_is_busy);
322 gov_show_one(od, powersave_bias);
323 
324 gov_attr_rw(sampling_rate);
325 gov_attr_rw(io_is_busy);
326 gov_attr_rw(up_threshold);
327 gov_attr_rw(sampling_down_factor);
328 gov_attr_rw(ignore_nice_load);
329 gov_attr_rw(powersave_bias);
330 
331 static struct attribute *od_attrs[] = {
332 	&sampling_rate.attr,
333 	&up_threshold.attr,
334 	&sampling_down_factor.attr,
335 	&ignore_nice_load.attr,
336 	&powersave_bias.attr,
337 	&io_is_busy.attr,
338 	NULL
339 };
340 ATTRIBUTE_GROUPS(od);
341 
342 /************************** sysfs end ************************/
343 
od_alloc(void)344 static struct policy_dbs_info *od_alloc(void)
345 {
346 	struct od_policy_dbs_info *dbs_info;
347 
348 	dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
349 	return dbs_info ? &dbs_info->policy_dbs : NULL;
350 }
351 
od_free(struct policy_dbs_info * policy_dbs)352 static void od_free(struct policy_dbs_info *policy_dbs)
353 {
354 	kfree(to_dbs_info(policy_dbs));
355 }
356 
od_init(struct dbs_data * dbs_data)357 static int od_init(struct dbs_data *dbs_data)
358 {
359 	struct od_dbs_tuners *tuners;
360 	u64 idle_time;
361 	int cpu;
362 
363 	tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
364 	if (!tuners)
365 		return -ENOMEM;
366 
367 	cpu = get_cpu();
368 	idle_time = get_cpu_idle_time_us(cpu, NULL);
369 	put_cpu();
370 	if (idle_time != -1ULL) {
371 		/* Idle micro accounting is supported. Use finer thresholds */
372 		dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
373 	} else {
374 		dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
375 	}
376 
377 	dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
378 	dbs_data->ignore_nice_load = 0;
379 	tuners->powersave_bias = default_powersave_bias;
380 	dbs_data->io_is_busy = should_io_be_busy();
381 
382 	dbs_data->tuners = tuners;
383 	return 0;
384 }
385 
od_exit(struct dbs_data * dbs_data)386 static void od_exit(struct dbs_data *dbs_data)
387 {
388 	kfree(dbs_data->tuners);
389 }
390 
od_start(struct cpufreq_policy * policy)391 static void od_start(struct cpufreq_policy *policy)
392 {
393 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
394 
395 	dbs_info->sample_type = OD_NORMAL_SAMPLE;
396 	ondemand_powersave_bias_init(policy);
397 }
398 
399 static struct od_ops od_ops = {
400 	.powersave_bias_target = generic_powersave_bias_target,
401 };
402 
403 static struct dbs_governor od_dbs_gov = {
404 	.gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
405 	.kobj_type = { .default_groups = od_groups },
406 	.gov_dbs_update = od_dbs_update,
407 	.alloc = od_alloc,
408 	.free = od_free,
409 	.init = od_init,
410 	.exit = od_exit,
411 	.start = od_start,
412 };
413 
414 #define CPU_FREQ_GOV_ONDEMAND	(od_dbs_gov.gov)
415 
od_set_powersave_bias(unsigned int powersave_bias)416 static void od_set_powersave_bias(unsigned int powersave_bias)
417 {
418 	unsigned int cpu;
419 	cpumask_var_t done;
420 
421 	if (!alloc_cpumask_var(&done, GFP_KERNEL))
422 		return;
423 
424 	default_powersave_bias = powersave_bias;
425 	cpumask_clear(done);
426 
427 	cpus_read_lock();
428 	for_each_online_cpu(cpu) {
429 		struct cpufreq_policy *policy;
430 		struct policy_dbs_info *policy_dbs;
431 		struct dbs_data *dbs_data;
432 		struct od_dbs_tuners *od_tuners;
433 
434 		if (cpumask_test_cpu(cpu, done))
435 			continue;
436 
437 		policy = cpufreq_cpu_get_raw(cpu);
438 		if (!policy || policy->governor != &CPU_FREQ_GOV_ONDEMAND)
439 			continue;
440 
441 		policy_dbs = policy->governor_data;
442 		if (!policy_dbs)
443 			continue;
444 
445 		cpumask_or(done, done, policy->cpus);
446 
447 		dbs_data = policy_dbs->dbs_data;
448 		od_tuners = dbs_data->tuners;
449 		od_tuners->powersave_bias = default_powersave_bias;
450 	}
451 	cpus_read_unlock();
452 
453 	free_cpumask_var(done);
454 }
455 
od_register_powersave_bias_handler(unsigned int (* f)(struct cpufreq_policy *,unsigned int,unsigned int),unsigned int powersave_bias)456 void od_register_powersave_bias_handler(unsigned int (*f)
457 		(struct cpufreq_policy *, unsigned int, unsigned int),
458 		unsigned int powersave_bias)
459 {
460 	od_ops.powersave_bias_target = f;
461 	od_set_powersave_bias(powersave_bias);
462 }
463 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
464 
od_unregister_powersave_bias_handler(void)465 void od_unregister_powersave_bias_handler(void)
466 {
467 	od_ops.powersave_bias_target = generic_powersave_bias_target;
468 	od_set_powersave_bias(0);
469 }
470 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
471 
472 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
473 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
474 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
475 	"Low Latency Frequency Transition capable processors");
476 MODULE_LICENSE("GPL");
477 
478 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
cpufreq_default_governor(void)479 struct cpufreq_governor *cpufreq_default_governor(void)
480 {
481 	return &CPU_FREQ_GOV_ONDEMAND;
482 }
483 #endif
484 
485 cpufreq_governor_init(CPU_FREQ_GOV_ONDEMAND);
486 cpufreq_governor_exit(CPU_FREQ_GOV_ONDEMAND);
487