1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * CPUFreq governor based on scheduler-provided CPU utilization data.
4  *
5  * Copyright (C) 2016, Intel Corporation
6  * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
7  */
8 
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 
11 #include "sched.h"
12 
13 #include <linux/sched/cpufreq.h>
14 #include <trace/events/power.h>
15 
16 #define IOWAIT_BOOST_MIN	(SCHED_CAPACITY_SCALE / 8)
17 
18 struct sugov_tunables {
19 	struct gov_attr_set	attr_set;
20 	unsigned int		rate_limit_us;
21 };
22 
23 struct sugov_policy {
24 	struct cpufreq_policy	*policy;
25 
26 	struct sugov_tunables	*tunables;
27 	struct list_head	tunables_hook;
28 
29 	raw_spinlock_t		update_lock;	/* For shared policies */
30 	u64			last_freq_update_time;
31 	s64			freq_update_delay_ns;
32 	unsigned int		next_freq;
33 	unsigned int		cached_raw_freq;
34 
35 	/* The next fields are only needed if fast switch cannot be used: */
36 	struct			irq_work irq_work;
37 	struct			kthread_work work;
38 	struct			mutex work_lock;
39 	struct			kthread_worker worker;
40 	struct task_struct	*thread;
41 	bool			work_in_progress;
42 
43 	bool			limits_changed;
44 	bool			need_freq_update;
45 };
46 
47 struct sugov_cpu {
48 	struct update_util_data	update_util;
49 	struct sugov_policy	*sg_policy;
50 	unsigned int		cpu;
51 
52 	bool			iowait_boost_pending;
53 	unsigned int		iowait_boost;
54 	u64			last_update;
55 
56 	unsigned long		util;
57 	unsigned long		bw_dl;
58 	unsigned long		max;
59 
60 	/* The field below is for single-CPU policies only: */
61 #ifdef CONFIG_NO_HZ_COMMON
62 	unsigned long		saved_idle_calls;
63 #endif
64 };
65 
66 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
67 
68 /************************ Governor internals ***********************/
69 
70 static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
71 {
72 	s64 delta_ns;
73 
74 	/*
75 	 * Since cpufreq_update_util() is called with rq->lock held for
76 	 * the @target_cpu, our per-CPU data is fully serialized.
77 	 *
78 	 * However, drivers cannot in general deal with cross-CPU
79 	 * requests, so while get_next_freq() will work, our
80 	 * sugov_update_commit() call may not for the fast switching platforms.
81 	 *
82 	 * Hence stop here for remote requests if they aren't supported
83 	 * by the hardware, as calculating the frequency is pointless if
84 	 * we cannot in fact act on it.
85 	 *
86 	 * This is needed on the slow switching platforms too to prevent CPUs
87 	 * going offline from leaving stale IRQ work items behind.
88 	 */
89 	if (!cpufreq_this_cpu_can_update(sg_policy->policy))
90 		return false;
91 
92 	if (unlikely(sg_policy->limits_changed)) {
93 		sg_policy->limits_changed = false;
94 		sg_policy->need_freq_update = true;
95 		return true;
96 	}
97 
98 	delta_ns = time - sg_policy->last_freq_update_time;
99 
100 	return delta_ns >= sg_policy->freq_update_delay_ns;
101 }
102 
103 static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
104 				   unsigned int next_freq)
105 {
106 	if (sg_policy->need_freq_update)
107 		sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
108 	else if (sg_policy->next_freq == next_freq)
109 		return false;
110 
111 	sg_policy->next_freq = next_freq;
112 	sg_policy->last_freq_update_time = time;
113 
114 	return true;
115 }
116 
117 static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
118 			      unsigned int next_freq)
119 {
120 	if (sugov_update_next_freq(sg_policy, time, next_freq))
121 		cpufreq_driver_fast_switch(sg_policy->policy, next_freq);
122 }
123 
124 static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
125 				  unsigned int next_freq)
126 {
127 	if (!sugov_update_next_freq(sg_policy, time, next_freq))
128 		return;
129 
130 	if (!sg_policy->work_in_progress) {
131 		sg_policy->work_in_progress = true;
132 		irq_work_queue(&sg_policy->irq_work);
133 	}
134 }
135 
136 /**
137  * get_next_freq - Compute a new frequency for a given cpufreq policy.
138  * @sg_policy: schedutil policy object to compute the new frequency for.
139  * @util: Current CPU utilization.
140  * @max: CPU capacity.
141  *
142  * If the utilization is frequency-invariant, choose the new frequency to be
143  * proportional to it, that is
144  *
145  * next_freq = C * max_freq * util / max
146  *
147  * Otherwise, approximate the would-be frequency-invariant utilization by
148  * util_raw * (curr_freq / max_freq) which leads to
149  *
150  * next_freq = C * curr_freq * util_raw / max
151  *
152  * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
153  *
154  * The lowest driver-supported frequency which is equal or greater than the raw
155  * next_freq (as calculated above) is returned, subject to policy min/max and
156  * cpufreq driver limitations.
157  */
158 static unsigned int get_next_freq(struct sugov_policy *sg_policy,
159 				  unsigned long util, unsigned long max)
160 {
161 	struct cpufreq_policy *policy = sg_policy->policy;
162 	unsigned int freq = arch_scale_freq_invariant() ?
163 				policy->cpuinfo.max_freq : policy->cur;
164 
165 	freq = map_util_freq(util, freq, max);
166 
167 	if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
168 		return sg_policy->next_freq;
169 
170 	sg_policy->cached_raw_freq = freq;
171 	return cpufreq_driver_resolve_freq(policy, freq);
172 }
173 
174 static void sugov_get_util(struct sugov_cpu *sg_cpu)
175 {
176 	struct rq *rq = cpu_rq(sg_cpu->cpu);
177 	unsigned long max = arch_scale_cpu_capacity(sg_cpu->cpu);
178 
179 	sg_cpu->max = max;
180 	sg_cpu->bw_dl = cpu_bw_dl(rq);
181 	sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(rq), max,
182 					  FREQUENCY_UTIL, NULL);
183 }
184 
185 /**
186  * sugov_iowait_reset() - Reset the IO boost status of a CPU.
187  * @sg_cpu: the sugov data for the CPU to boost
188  * @time: the update time from the caller
189  * @set_iowait_boost: true if an IO boost has been requested
190  *
191  * The IO wait boost of a task is disabled after a tick since the last update
192  * of a CPU. If a new IO wait boost is requested after more then a tick, then
193  * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
194  * efficiency by ignoring sporadic wakeups from IO.
195  */
196 static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
197 			       bool set_iowait_boost)
198 {
199 	s64 delta_ns = time - sg_cpu->last_update;
200 
201 	/* Reset boost only if a tick has elapsed since last request */
202 	if (delta_ns <= TICK_NSEC)
203 		return false;
204 
205 	sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
206 	sg_cpu->iowait_boost_pending = set_iowait_boost;
207 
208 	return true;
209 }
210 
211 /**
212  * sugov_iowait_boost() - Updates the IO boost status of a CPU.
213  * @sg_cpu: the sugov data for the CPU to boost
214  * @time: the update time from the caller
215  * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
216  *
217  * Each time a task wakes up after an IO operation, the CPU utilization can be
218  * boosted to a certain utilization which doubles at each "frequent and
219  * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
220  * of the maximum OPP.
221  *
222  * To keep doubling, an IO boost has to be requested at least once per tick,
223  * otherwise we restart from the utilization of the minimum OPP.
224  */
225 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
226 			       unsigned int flags)
227 {
228 	bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
229 
230 	/* Reset boost if the CPU appears to have been idle enough */
231 	if (sg_cpu->iowait_boost &&
232 	    sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
233 		return;
234 
235 	/* Boost only tasks waking up after IO */
236 	if (!set_iowait_boost)
237 		return;
238 
239 	/* Ensure boost doubles only one time at each request */
240 	if (sg_cpu->iowait_boost_pending)
241 		return;
242 	sg_cpu->iowait_boost_pending = true;
243 
244 	/* Double the boost at each request */
245 	if (sg_cpu->iowait_boost) {
246 		sg_cpu->iowait_boost =
247 			min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
248 		return;
249 	}
250 
251 	/* First wakeup after IO: start with minimum boost */
252 	sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
253 }
254 
255 /**
256  * sugov_iowait_apply() - Apply the IO boost to a CPU.
257  * @sg_cpu: the sugov data for the cpu to boost
258  * @time: the update time from the caller
259  *
260  * A CPU running a task which woken up after an IO operation can have its
261  * utilization boosted to speed up the completion of those IO operations.
262  * The IO boost value is increased each time a task wakes up from IO, in
263  * sugov_iowait_apply(), and it's instead decreased by this function,
264  * each time an increase has not been requested (!iowait_boost_pending).
265  *
266  * A CPU which also appears to have been idle for at least one tick has also
267  * its IO boost utilization reset.
268  *
269  * This mechanism is designed to boost high frequently IO waiting tasks, while
270  * being more conservative on tasks which does sporadic IO operations.
271  */
272 static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time)
273 {
274 	unsigned long boost;
275 
276 	/* No boost currently required */
277 	if (!sg_cpu->iowait_boost)
278 		return;
279 
280 	/* Reset boost if the CPU appears to have been idle enough */
281 	if (sugov_iowait_reset(sg_cpu, time, false))
282 		return;
283 
284 	if (!sg_cpu->iowait_boost_pending) {
285 		/*
286 		 * No boost pending; reduce the boost value.
287 		 */
288 		sg_cpu->iowait_boost >>= 1;
289 		if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
290 			sg_cpu->iowait_boost = 0;
291 			return;
292 		}
293 	}
294 
295 	sg_cpu->iowait_boost_pending = false;
296 
297 	/*
298 	 * sg_cpu->util is already in capacity scale; convert iowait_boost
299 	 * into the same scale so we can compare.
300 	 */
301 	boost = (sg_cpu->iowait_boost * sg_cpu->max) >> SCHED_CAPACITY_SHIFT;
302 	if (sg_cpu->util < boost)
303 		sg_cpu->util = boost;
304 }
305 
306 #ifdef CONFIG_NO_HZ_COMMON
307 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
308 {
309 	unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
310 	bool ret = idle_calls == sg_cpu->saved_idle_calls;
311 
312 	sg_cpu->saved_idle_calls = idle_calls;
313 	return ret;
314 }
315 #else
316 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
317 #endif /* CONFIG_NO_HZ_COMMON */
318 
319 /*
320  * Make sugov_should_update_freq() ignore the rate limit when DL
321  * has increased the utilization.
322  */
323 static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
324 {
325 	if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
326 		sg_policy->limits_changed = true;
327 }
328 
329 static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
330 					      u64 time, unsigned int flags)
331 {
332 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
333 
334 	sugov_iowait_boost(sg_cpu, time, flags);
335 	sg_cpu->last_update = time;
336 
337 	ignore_dl_rate_limit(sg_cpu, sg_policy);
338 
339 	if (!sugov_should_update_freq(sg_policy, time))
340 		return false;
341 
342 	sugov_get_util(sg_cpu);
343 	sugov_iowait_apply(sg_cpu, time);
344 
345 	return true;
346 }
347 
348 static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
349 				     unsigned int flags)
350 {
351 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
352 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
353 	unsigned int cached_freq = sg_policy->cached_raw_freq;
354 	unsigned int next_f;
355 
356 	if (!sugov_update_single_common(sg_cpu, time, flags))
357 		return;
358 
359 	next_f = get_next_freq(sg_policy, sg_cpu->util, sg_cpu->max);
360 	/*
361 	 * Do not reduce the frequency if the CPU has not been idle
362 	 * recently, as the reduction is likely to be premature then.
363 	 */
364 	if (sugov_cpu_is_busy(sg_cpu) && next_f < sg_policy->next_freq) {
365 		next_f = sg_policy->next_freq;
366 
367 		/* Restore cached freq as next_freq has changed */
368 		sg_policy->cached_raw_freq = cached_freq;
369 	}
370 
371 	/*
372 	 * This code runs under rq->lock for the target CPU, so it won't run
373 	 * concurrently on two different CPUs for the same target and it is not
374 	 * necessary to acquire the lock in the fast switch case.
375 	 */
376 	if (sg_policy->policy->fast_switch_enabled) {
377 		sugov_fast_switch(sg_policy, time, next_f);
378 	} else {
379 		raw_spin_lock(&sg_policy->update_lock);
380 		sugov_deferred_update(sg_policy, time, next_f);
381 		raw_spin_unlock(&sg_policy->update_lock);
382 	}
383 }
384 
385 static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
386 				     unsigned int flags)
387 {
388 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
389 	unsigned long prev_util = sg_cpu->util;
390 
391 	/*
392 	 * Fall back to the "frequency" path if frequency invariance is not
393 	 * supported, because the direct mapping between the utilization and
394 	 * the performance levels depends on the frequency invariance.
395 	 */
396 	if (!arch_scale_freq_invariant()) {
397 		sugov_update_single_freq(hook, time, flags);
398 		return;
399 	}
400 
401 	if (!sugov_update_single_common(sg_cpu, time, flags))
402 		return;
403 
404 	/*
405 	 * Do not reduce the target performance level if the CPU has not been
406 	 * idle recently, as the reduction is likely to be premature then.
407 	 */
408 	if (sugov_cpu_is_busy(sg_cpu) && sg_cpu->util < prev_util)
409 		sg_cpu->util = prev_util;
410 
411 	cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl),
412 				   map_util_perf(sg_cpu->util), sg_cpu->max);
413 
414 	sg_cpu->sg_policy->last_freq_update_time = time;
415 }
416 
417 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
418 {
419 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
420 	struct cpufreq_policy *policy = sg_policy->policy;
421 	unsigned long util = 0, max = 1;
422 	unsigned int j;
423 
424 	for_each_cpu(j, policy->cpus) {
425 		struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
426 		unsigned long j_util, j_max;
427 
428 		sugov_get_util(j_sg_cpu);
429 		sugov_iowait_apply(j_sg_cpu, time);
430 		j_util = j_sg_cpu->util;
431 		j_max = j_sg_cpu->max;
432 
433 		if (j_util * max > j_max * util) {
434 			util = j_util;
435 			max = j_max;
436 		}
437 	}
438 
439 	return get_next_freq(sg_policy, util, max);
440 }
441 
442 static void
443 sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
444 {
445 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
446 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
447 	unsigned int next_f;
448 
449 	raw_spin_lock(&sg_policy->update_lock);
450 
451 	sugov_iowait_boost(sg_cpu, time, flags);
452 	sg_cpu->last_update = time;
453 
454 	ignore_dl_rate_limit(sg_cpu, sg_policy);
455 
456 	if (sugov_should_update_freq(sg_policy, time)) {
457 		next_f = sugov_next_freq_shared(sg_cpu, time);
458 
459 		if (sg_policy->policy->fast_switch_enabled)
460 			sugov_fast_switch(sg_policy, time, next_f);
461 		else
462 			sugov_deferred_update(sg_policy, time, next_f);
463 	}
464 
465 	raw_spin_unlock(&sg_policy->update_lock);
466 }
467 
468 static void sugov_work(struct kthread_work *work)
469 {
470 	struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
471 	unsigned int freq;
472 	unsigned long flags;
473 
474 	/*
475 	 * Hold sg_policy->update_lock shortly to handle the case where:
476 	 * incase sg_policy->next_freq is read here, and then updated by
477 	 * sugov_deferred_update() just before work_in_progress is set to false
478 	 * here, we may miss queueing the new update.
479 	 *
480 	 * Note: If a work was queued after the update_lock is released,
481 	 * sugov_work() will just be called again by kthread_work code; and the
482 	 * request will be proceed before the sugov thread sleeps.
483 	 */
484 	raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
485 	freq = sg_policy->next_freq;
486 	sg_policy->work_in_progress = false;
487 	raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
488 
489 	mutex_lock(&sg_policy->work_lock);
490 	__cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
491 	mutex_unlock(&sg_policy->work_lock);
492 }
493 
494 static void sugov_irq_work(struct irq_work *irq_work)
495 {
496 	struct sugov_policy *sg_policy;
497 
498 	sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
499 
500 	kthread_queue_work(&sg_policy->worker, &sg_policy->work);
501 }
502 
503 /************************** sysfs interface ************************/
504 
505 static struct sugov_tunables *global_tunables;
506 static DEFINE_MUTEX(global_tunables_lock);
507 
508 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
509 {
510 	return container_of(attr_set, struct sugov_tunables, attr_set);
511 }
512 
513 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
514 {
515 	struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
516 
517 	return sprintf(buf, "%u\n", tunables->rate_limit_us);
518 }
519 
520 static ssize_t
521 rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
522 {
523 	struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
524 	struct sugov_policy *sg_policy;
525 	unsigned int rate_limit_us;
526 
527 	if (kstrtouint(buf, 10, &rate_limit_us))
528 		return -EINVAL;
529 
530 	tunables->rate_limit_us = rate_limit_us;
531 
532 	list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
533 		sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
534 
535 	return count;
536 }
537 
538 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
539 
540 static struct attribute *sugov_attrs[] = {
541 	&rate_limit_us.attr,
542 	NULL
543 };
544 ATTRIBUTE_GROUPS(sugov);
545 
546 static struct kobj_type sugov_tunables_ktype = {
547 	.default_groups = sugov_groups,
548 	.sysfs_ops = &governor_sysfs_ops,
549 };
550 
551 /********************** cpufreq governor interface *********************/
552 
553 struct cpufreq_governor schedutil_gov;
554 
555 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
556 {
557 	struct sugov_policy *sg_policy;
558 
559 	sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
560 	if (!sg_policy)
561 		return NULL;
562 
563 	sg_policy->policy = policy;
564 	raw_spin_lock_init(&sg_policy->update_lock);
565 	return sg_policy;
566 }
567 
568 static void sugov_policy_free(struct sugov_policy *sg_policy)
569 {
570 	kfree(sg_policy);
571 }
572 
573 static int sugov_kthread_create(struct sugov_policy *sg_policy)
574 {
575 	struct task_struct *thread;
576 	struct sched_attr attr = {
577 		.size		= sizeof(struct sched_attr),
578 		.sched_policy	= SCHED_DEADLINE,
579 		.sched_flags	= SCHED_FLAG_SUGOV,
580 		.sched_nice	= 0,
581 		.sched_priority	= 0,
582 		/*
583 		 * Fake (unused) bandwidth; workaround to "fix"
584 		 * priority inheritance.
585 		 */
586 		.sched_runtime	=  1000000,
587 		.sched_deadline = 10000000,
588 		.sched_period	= 10000000,
589 	};
590 	struct cpufreq_policy *policy = sg_policy->policy;
591 	int ret;
592 
593 	/* kthread only required for slow path */
594 	if (policy->fast_switch_enabled)
595 		return 0;
596 
597 	kthread_init_work(&sg_policy->work, sugov_work);
598 	kthread_init_worker(&sg_policy->worker);
599 	thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
600 				"sugov:%d",
601 				cpumask_first(policy->related_cpus));
602 	if (IS_ERR(thread)) {
603 		pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
604 		return PTR_ERR(thread);
605 	}
606 
607 	ret = sched_setattr_nocheck(thread, &attr);
608 	if (ret) {
609 		kthread_stop(thread);
610 		pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
611 		return ret;
612 	}
613 
614 	sg_policy->thread = thread;
615 	kthread_bind_mask(thread, policy->related_cpus);
616 	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
617 	mutex_init(&sg_policy->work_lock);
618 
619 	wake_up_process(thread);
620 
621 	return 0;
622 }
623 
624 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
625 {
626 	/* kthread only required for slow path */
627 	if (sg_policy->policy->fast_switch_enabled)
628 		return;
629 
630 	kthread_flush_worker(&sg_policy->worker);
631 	kthread_stop(sg_policy->thread);
632 	mutex_destroy(&sg_policy->work_lock);
633 }
634 
635 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
636 {
637 	struct sugov_tunables *tunables;
638 
639 	tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
640 	if (tunables) {
641 		gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
642 		if (!have_governor_per_policy())
643 			global_tunables = tunables;
644 	}
645 	return tunables;
646 }
647 
648 static void sugov_tunables_free(struct sugov_tunables *tunables)
649 {
650 	if (!have_governor_per_policy())
651 		global_tunables = NULL;
652 
653 	kfree(tunables);
654 }
655 
656 static int sugov_init(struct cpufreq_policy *policy)
657 {
658 	struct sugov_policy *sg_policy;
659 	struct sugov_tunables *tunables;
660 	int ret = 0;
661 
662 	/* State should be equivalent to EXIT */
663 	if (policy->governor_data)
664 		return -EBUSY;
665 
666 	cpufreq_enable_fast_switch(policy);
667 
668 	sg_policy = sugov_policy_alloc(policy);
669 	if (!sg_policy) {
670 		ret = -ENOMEM;
671 		goto disable_fast_switch;
672 	}
673 
674 	ret = sugov_kthread_create(sg_policy);
675 	if (ret)
676 		goto free_sg_policy;
677 
678 	mutex_lock(&global_tunables_lock);
679 
680 	if (global_tunables) {
681 		if (WARN_ON(have_governor_per_policy())) {
682 			ret = -EINVAL;
683 			goto stop_kthread;
684 		}
685 		policy->governor_data = sg_policy;
686 		sg_policy->tunables = global_tunables;
687 
688 		gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
689 		goto out;
690 	}
691 
692 	tunables = sugov_tunables_alloc(sg_policy);
693 	if (!tunables) {
694 		ret = -ENOMEM;
695 		goto stop_kthread;
696 	}
697 
698 	tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
699 
700 	policy->governor_data = sg_policy;
701 	sg_policy->tunables = tunables;
702 
703 	ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
704 				   get_governor_parent_kobj(policy), "%s",
705 				   schedutil_gov.name);
706 	if (ret)
707 		goto fail;
708 
709 out:
710 	mutex_unlock(&global_tunables_lock);
711 	return 0;
712 
713 fail:
714 	kobject_put(&tunables->attr_set.kobj);
715 	policy->governor_data = NULL;
716 	sugov_tunables_free(tunables);
717 
718 stop_kthread:
719 	sugov_kthread_stop(sg_policy);
720 	mutex_unlock(&global_tunables_lock);
721 
722 free_sg_policy:
723 	sugov_policy_free(sg_policy);
724 
725 disable_fast_switch:
726 	cpufreq_disable_fast_switch(policy);
727 
728 	pr_err("initialization failed (error %d)\n", ret);
729 	return ret;
730 }
731 
732 static void sugov_exit(struct cpufreq_policy *policy)
733 {
734 	struct sugov_policy *sg_policy = policy->governor_data;
735 	struct sugov_tunables *tunables = sg_policy->tunables;
736 	unsigned int count;
737 
738 	mutex_lock(&global_tunables_lock);
739 
740 	count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
741 	policy->governor_data = NULL;
742 	if (!count)
743 		sugov_tunables_free(tunables);
744 
745 	mutex_unlock(&global_tunables_lock);
746 
747 	sugov_kthread_stop(sg_policy);
748 	sugov_policy_free(sg_policy);
749 	cpufreq_disable_fast_switch(policy);
750 }
751 
752 static int sugov_start(struct cpufreq_policy *policy)
753 {
754 	struct sugov_policy *sg_policy = policy->governor_data;
755 	void (*uu)(struct update_util_data *data, u64 time, unsigned int flags);
756 	unsigned int cpu;
757 
758 	sg_policy->freq_update_delay_ns	= sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
759 	sg_policy->last_freq_update_time	= 0;
760 	sg_policy->next_freq			= 0;
761 	sg_policy->work_in_progress		= false;
762 	sg_policy->limits_changed		= false;
763 	sg_policy->cached_raw_freq		= 0;
764 
765 	sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
766 
767 	for_each_cpu(cpu, policy->cpus) {
768 		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
769 
770 		memset(sg_cpu, 0, sizeof(*sg_cpu));
771 		sg_cpu->cpu			= cpu;
772 		sg_cpu->sg_policy		= sg_policy;
773 	}
774 
775 	if (policy_is_shared(policy))
776 		uu = sugov_update_shared;
777 	else if (policy->fast_switch_enabled && cpufreq_driver_has_adjust_perf())
778 		uu = sugov_update_single_perf;
779 	else
780 		uu = sugov_update_single_freq;
781 
782 	for_each_cpu(cpu, policy->cpus) {
783 		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
784 
785 		cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, uu);
786 	}
787 	return 0;
788 }
789 
790 static void sugov_stop(struct cpufreq_policy *policy)
791 {
792 	struct sugov_policy *sg_policy = policy->governor_data;
793 	unsigned int cpu;
794 
795 	for_each_cpu(cpu, policy->cpus)
796 		cpufreq_remove_update_util_hook(cpu);
797 
798 	synchronize_rcu();
799 
800 	if (!policy->fast_switch_enabled) {
801 		irq_work_sync(&sg_policy->irq_work);
802 		kthread_cancel_work_sync(&sg_policy->work);
803 	}
804 }
805 
806 static void sugov_limits(struct cpufreq_policy *policy)
807 {
808 	struct sugov_policy *sg_policy = policy->governor_data;
809 
810 	if (!policy->fast_switch_enabled) {
811 		mutex_lock(&sg_policy->work_lock);
812 		cpufreq_policy_apply_limits(policy);
813 		mutex_unlock(&sg_policy->work_lock);
814 	}
815 
816 	sg_policy->limits_changed = true;
817 }
818 
819 struct cpufreq_governor schedutil_gov = {
820 	.name			= "schedutil",
821 	.owner			= THIS_MODULE,
822 	.flags			= CPUFREQ_GOV_DYNAMIC_SWITCHING,
823 	.init			= sugov_init,
824 	.exit			= sugov_exit,
825 	.start			= sugov_start,
826 	.stop			= sugov_stop,
827 	.limits			= sugov_limits,
828 };
829 
830 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
831 struct cpufreq_governor *cpufreq_default_governor(void)
832 {
833 	return &schedutil_gov;
834 }
835 #endif
836 
837 cpufreq_governor_init(schedutil_gov);
838 
839 #ifdef CONFIG_ENERGY_MODEL
840 static void rebuild_sd_workfn(struct work_struct *work)
841 {
842 	rebuild_sched_domains_energy();
843 }
844 static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
845 
846 /*
847  * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
848  * on governor changes to make sure the scheduler knows about it.
849  */
850 void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
851 				  struct cpufreq_governor *old_gov)
852 {
853 	if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
854 		/*
855 		 * When called from the cpufreq_register_driver() path, the
856 		 * cpu_hotplug_lock is already held, so use a work item to
857 		 * avoid nested locking in rebuild_sched_domains().
858 		 */
859 		schedule_work(&rebuild_sd_work);
860 	}
861 
862 }
863 #endif
864