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 IOWAIT_BOOST_MIN	(SCHED_CAPACITY_SCALE / 8)
10 
11 struct sugov_tunables {
12 	struct gov_attr_set	attr_set;
13 	unsigned int		rate_limit_us;
14 };
15 
16 struct sugov_policy {
17 	struct cpufreq_policy	*policy;
18 
19 	struct sugov_tunables	*tunables;
20 	struct list_head	tunables_hook;
21 
22 	raw_spinlock_t		update_lock;
23 	u64			last_freq_update_time;
24 	s64			freq_update_delay_ns;
25 	unsigned int		next_freq;
26 	unsigned int		cached_raw_freq;
27 
28 	/* The next fields are only needed if fast switch cannot be used: */
29 	struct			irq_work irq_work;
30 	struct			kthread_work work;
31 	struct			mutex work_lock;
32 	struct			kthread_worker worker;
33 	struct task_struct	*thread;
34 	bool			work_in_progress;
35 
36 	bool			limits_changed;
37 	bool			need_freq_update;
38 };
39 
40 struct sugov_cpu {
41 	struct update_util_data	update_util;
42 	struct sugov_policy	*sg_policy;
43 	unsigned int		cpu;
44 
45 	bool			iowait_boost_pending;
46 	unsigned int		iowait_boost;
47 	u64			last_update;
48 
49 	unsigned long		util;
50 	unsigned long		bw_dl;
51 
52 	/* The field below is for single-CPU policies only: */
53 #ifdef CONFIG_NO_HZ_COMMON
54 	unsigned long		saved_idle_calls;
55 #endif
56 };
57 
58 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
59 
60 /************************ Governor internals ***********************/
61 
62 static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
63 {
64 	s64 delta_ns;
65 
66 	/*
67 	 * Since cpufreq_update_util() is called with rq->lock held for
68 	 * the @target_cpu, our per-CPU data is fully serialized.
69 	 *
70 	 * However, drivers cannot in general deal with cross-CPU
71 	 * requests, so while get_next_freq() will work, our
72 	 * sugov_update_commit() call may not for the fast switching platforms.
73 	 *
74 	 * Hence stop here for remote requests if they aren't supported
75 	 * by the hardware, as calculating the frequency is pointless if
76 	 * we cannot in fact act on it.
77 	 *
78 	 * This is needed on the slow switching platforms too to prevent CPUs
79 	 * going offline from leaving stale IRQ work items behind.
80 	 */
81 	if (!cpufreq_this_cpu_can_update(sg_policy->policy))
82 		return false;
83 
84 	if (unlikely(sg_policy->limits_changed)) {
85 		sg_policy->limits_changed = false;
86 		sg_policy->need_freq_update = true;
87 		return true;
88 	}
89 
90 	delta_ns = time - sg_policy->last_freq_update_time;
91 
92 	return delta_ns >= sg_policy->freq_update_delay_ns;
93 }
94 
95 static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
96 				   unsigned int next_freq)
97 {
98 	if (sg_policy->need_freq_update)
99 		sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
100 	else if (sg_policy->next_freq == next_freq)
101 		return false;
102 
103 	sg_policy->next_freq = next_freq;
104 	sg_policy->last_freq_update_time = time;
105 
106 	return true;
107 }
108 
109 static void sugov_deferred_update(struct sugov_policy *sg_policy)
110 {
111 	if (!sg_policy->work_in_progress) {
112 		sg_policy->work_in_progress = true;
113 		irq_work_queue(&sg_policy->irq_work);
114 	}
115 }
116 
117 /**
118  * get_next_freq - Compute a new frequency for a given cpufreq policy.
119  * @sg_policy: schedutil policy object to compute the new frequency for.
120  * @util: Current CPU utilization.
121  * @max: CPU capacity.
122  *
123  * If the utilization is frequency-invariant, choose the new frequency to be
124  * proportional to it, that is
125  *
126  * next_freq = C * max_freq * util / max
127  *
128  * Otherwise, approximate the would-be frequency-invariant utilization by
129  * util_raw * (curr_freq / max_freq) which leads to
130  *
131  * next_freq = C * curr_freq * util_raw / max
132  *
133  * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
134  *
135  * The lowest driver-supported frequency which is equal or greater than the raw
136  * next_freq (as calculated above) is returned, subject to policy min/max and
137  * cpufreq driver limitations.
138  */
139 static unsigned int get_next_freq(struct sugov_policy *sg_policy,
140 				  unsigned long util, unsigned long max)
141 {
142 	struct cpufreq_policy *policy = sg_policy->policy;
143 	unsigned int freq = arch_scale_freq_invariant() ?
144 				policy->cpuinfo.max_freq : policy->cur;
145 
146 	util = map_util_perf(util);
147 	freq = map_util_freq(util, freq, max);
148 
149 	if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
150 		return sg_policy->next_freq;
151 
152 	sg_policy->cached_raw_freq = freq;
153 	return cpufreq_driver_resolve_freq(policy, freq);
154 }
155 
156 static void sugov_get_util(struct sugov_cpu *sg_cpu)
157 {
158 	unsigned long util = cpu_util_cfs_boost(sg_cpu->cpu);
159 	struct rq *rq = cpu_rq(sg_cpu->cpu);
160 
161 	sg_cpu->bw_dl = cpu_bw_dl(rq);
162 	sg_cpu->util = effective_cpu_util(sg_cpu->cpu, util,
163 					  FREQUENCY_UTIL, NULL);
164 }
165 
166 /**
167  * sugov_iowait_reset() - Reset the IO boost status of a CPU.
168  * @sg_cpu: the sugov data for the CPU to boost
169  * @time: the update time from the caller
170  * @set_iowait_boost: true if an IO boost has been requested
171  *
172  * The IO wait boost of a task is disabled after a tick since the last update
173  * of a CPU. If a new IO wait boost is requested after more then a tick, then
174  * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
175  * efficiency by ignoring sporadic wakeups from IO.
176  */
177 static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
178 			       bool set_iowait_boost)
179 {
180 	s64 delta_ns = time - sg_cpu->last_update;
181 
182 	/* Reset boost only if a tick has elapsed since last request */
183 	if (delta_ns <= TICK_NSEC)
184 		return false;
185 
186 	sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
187 	sg_cpu->iowait_boost_pending = set_iowait_boost;
188 
189 	return true;
190 }
191 
192 /**
193  * sugov_iowait_boost() - Updates the IO boost status of a CPU.
194  * @sg_cpu: the sugov data for the CPU to boost
195  * @time: the update time from the caller
196  * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
197  *
198  * Each time a task wakes up after an IO operation, the CPU utilization can be
199  * boosted to a certain utilization which doubles at each "frequent and
200  * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
201  * of the maximum OPP.
202  *
203  * To keep doubling, an IO boost has to be requested at least once per tick,
204  * otherwise we restart from the utilization of the minimum OPP.
205  */
206 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
207 			       unsigned int flags)
208 {
209 	bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
210 
211 	/* Reset boost if the CPU appears to have been idle enough */
212 	if (sg_cpu->iowait_boost &&
213 	    sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
214 		return;
215 
216 	/* Boost only tasks waking up after IO */
217 	if (!set_iowait_boost)
218 		return;
219 
220 	/* Ensure boost doubles only one time at each request */
221 	if (sg_cpu->iowait_boost_pending)
222 		return;
223 	sg_cpu->iowait_boost_pending = true;
224 
225 	/* Double the boost at each request */
226 	if (sg_cpu->iowait_boost) {
227 		sg_cpu->iowait_boost =
228 			min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
229 		return;
230 	}
231 
232 	/* First wakeup after IO: start with minimum boost */
233 	sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
234 }
235 
236 /**
237  * sugov_iowait_apply() - Apply the IO boost to a CPU.
238  * @sg_cpu: the sugov data for the cpu to boost
239  * @time: the update time from the caller
240  * @max_cap: the max CPU capacity
241  *
242  * A CPU running a task which woken up after an IO operation can have its
243  * utilization boosted to speed up the completion of those IO operations.
244  * The IO boost value is increased each time a task wakes up from IO, in
245  * sugov_iowait_apply(), and it's instead decreased by this function,
246  * each time an increase has not been requested (!iowait_boost_pending).
247  *
248  * A CPU which also appears to have been idle for at least one tick has also
249  * its IO boost utilization reset.
250  *
251  * This mechanism is designed to boost high frequently IO waiting tasks, while
252  * being more conservative on tasks which does sporadic IO operations.
253  */
254 static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
255 			       unsigned long max_cap)
256 {
257 	unsigned long boost;
258 
259 	/* No boost currently required */
260 	if (!sg_cpu->iowait_boost)
261 		return;
262 
263 	/* Reset boost if the CPU appears to have been idle enough */
264 	if (sugov_iowait_reset(sg_cpu, time, false))
265 		return;
266 
267 	if (!sg_cpu->iowait_boost_pending) {
268 		/*
269 		 * No boost pending; reduce the boost value.
270 		 */
271 		sg_cpu->iowait_boost >>= 1;
272 		if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
273 			sg_cpu->iowait_boost = 0;
274 			return;
275 		}
276 	}
277 
278 	sg_cpu->iowait_boost_pending = false;
279 
280 	/*
281 	 * sg_cpu->util is already in capacity scale; convert iowait_boost
282 	 * into the same scale so we can compare.
283 	 */
284 	boost = (sg_cpu->iowait_boost * max_cap) >> SCHED_CAPACITY_SHIFT;
285 	boost = uclamp_rq_util_with(cpu_rq(sg_cpu->cpu), boost, NULL);
286 	if (sg_cpu->util < boost)
287 		sg_cpu->util = boost;
288 }
289 
290 #ifdef CONFIG_NO_HZ_COMMON
291 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
292 {
293 	unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
294 	bool ret = idle_calls == sg_cpu->saved_idle_calls;
295 
296 	sg_cpu->saved_idle_calls = idle_calls;
297 	return ret;
298 }
299 #else
300 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
301 #endif /* CONFIG_NO_HZ_COMMON */
302 
303 /*
304  * Make sugov_should_update_freq() ignore the rate limit when DL
305  * has increased the utilization.
306  */
307 static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu)
308 {
309 	if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
310 		sg_cpu->sg_policy->limits_changed = true;
311 }
312 
313 static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
314 					      u64 time, unsigned long max_cap,
315 					      unsigned int flags)
316 {
317 	sugov_iowait_boost(sg_cpu, time, flags);
318 	sg_cpu->last_update = time;
319 
320 	ignore_dl_rate_limit(sg_cpu);
321 
322 	if (!sugov_should_update_freq(sg_cpu->sg_policy, time))
323 		return false;
324 
325 	sugov_get_util(sg_cpu);
326 	sugov_iowait_apply(sg_cpu, time, max_cap);
327 
328 	return true;
329 }
330 
331 static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
332 				     unsigned int flags)
333 {
334 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
335 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
336 	unsigned int cached_freq = sg_policy->cached_raw_freq;
337 	unsigned long max_cap;
338 	unsigned int next_f;
339 
340 	max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
341 
342 	if (!sugov_update_single_common(sg_cpu, time, max_cap, flags))
343 		return;
344 
345 	next_f = get_next_freq(sg_policy, sg_cpu->util, max_cap);
346 	/*
347 	 * Do not reduce the frequency if the CPU has not been idle
348 	 * recently, as the reduction is likely to be premature then.
349 	 *
350 	 * Except when the rq is capped by uclamp_max.
351 	 */
352 	if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) &&
353 	    sugov_cpu_is_busy(sg_cpu) && next_f < sg_policy->next_freq &&
354 	    !sg_policy->need_freq_update) {
355 		next_f = sg_policy->next_freq;
356 
357 		/* Restore cached freq as next_freq has changed */
358 		sg_policy->cached_raw_freq = cached_freq;
359 	}
360 
361 	if (!sugov_update_next_freq(sg_policy, time, next_f))
362 		return;
363 
364 	/*
365 	 * This code runs under rq->lock for the target CPU, so it won't run
366 	 * concurrently on two different CPUs for the same target and it is not
367 	 * necessary to acquire the lock in the fast switch case.
368 	 */
369 	if (sg_policy->policy->fast_switch_enabled) {
370 		cpufreq_driver_fast_switch(sg_policy->policy, next_f);
371 	} else {
372 		raw_spin_lock(&sg_policy->update_lock);
373 		sugov_deferred_update(sg_policy);
374 		raw_spin_unlock(&sg_policy->update_lock);
375 	}
376 }
377 
378 static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
379 				     unsigned int flags)
380 {
381 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
382 	unsigned long prev_util = sg_cpu->util;
383 	unsigned long max_cap;
384 
385 	/*
386 	 * Fall back to the "frequency" path if frequency invariance is not
387 	 * supported, because the direct mapping between the utilization and
388 	 * the performance levels depends on the frequency invariance.
389 	 */
390 	if (!arch_scale_freq_invariant()) {
391 		sugov_update_single_freq(hook, time, flags);
392 		return;
393 	}
394 
395 	max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
396 
397 	if (!sugov_update_single_common(sg_cpu, time, max_cap, flags))
398 		return;
399 
400 	/*
401 	 * Do not reduce the target performance level if the CPU has not been
402 	 * idle recently, as the reduction is likely to be premature then.
403 	 *
404 	 * Except when the rq is capped by uclamp_max.
405 	 */
406 	if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) &&
407 	    sugov_cpu_is_busy(sg_cpu) && sg_cpu->util < prev_util)
408 		sg_cpu->util = prev_util;
409 
410 	cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl),
411 				   map_util_perf(sg_cpu->util), max_cap);
412 
413 	sg_cpu->sg_policy->last_freq_update_time = time;
414 }
415 
416 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
417 {
418 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
419 	struct cpufreq_policy *policy = sg_policy->policy;
420 	unsigned long util = 0, max_cap;
421 	unsigned int j;
422 
423 	max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
424 
425 	for_each_cpu(j, policy->cpus) {
426 		struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
427 
428 		sugov_get_util(j_sg_cpu);
429 		sugov_iowait_apply(j_sg_cpu, time, max_cap);
430 
431 		util = max(j_sg_cpu->util, util);
432 	}
433 
434 	return get_next_freq(sg_policy, util, max_cap);
435 }
436 
437 static void
438 sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
439 {
440 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
441 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
442 	unsigned int next_f;
443 
444 	raw_spin_lock(&sg_policy->update_lock);
445 
446 	sugov_iowait_boost(sg_cpu, time, flags);
447 	sg_cpu->last_update = time;
448 
449 	ignore_dl_rate_limit(sg_cpu);
450 
451 	if (sugov_should_update_freq(sg_policy, time)) {
452 		next_f = sugov_next_freq_shared(sg_cpu, time);
453 
454 		if (!sugov_update_next_freq(sg_policy, time, next_f))
455 			goto unlock;
456 
457 		if (sg_policy->policy->fast_switch_enabled)
458 			cpufreq_driver_fast_switch(sg_policy->policy, next_f);
459 		else
460 			sugov_deferred_update(sg_policy);
461 	}
462 unlock:
463 	raw_spin_unlock(&sg_policy->update_lock);
464 }
465 
466 static void sugov_work(struct kthread_work *work)
467 {
468 	struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
469 	unsigned int freq;
470 	unsigned long flags;
471 
472 	/*
473 	 * Hold sg_policy->update_lock shortly to handle the case where:
474 	 * in case sg_policy->next_freq is read here, and then updated by
475 	 * sugov_deferred_update() just before work_in_progress is set to false
476 	 * here, we may miss queueing the new update.
477 	 *
478 	 * Note: If a work was queued after the update_lock is released,
479 	 * sugov_work() will just be called again by kthread_work code; and the
480 	 * request will be proceed before the sugov thread sleeps.
481 	 */
482 	raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
483 	freq = sg_policy->next_freq;
484 	sg_policy->work_in_progress = false;
485 	raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
486 
487 	mutex_lock(&sg_policy->work_lock);
488 	__cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
489 	mutex_unlock(&sg_policy->work_lock);
490 }
491 
492 static void sugov_irq_work(struct irq_work *irq_work)
493 {
494 	struct sugov_policy *sg_policy;
495 
496 	sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
497 
498 	kthread_queue_work(&sg_policy->worker, &sg_policy->work);
499 }
500 
501 /************************** sysfs interface ************************/
502 
503 static struct sugov_tunables *global_tunables;
504 static DEFINE_MUTEX(global_tunables_lock);
505 
506 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
507 {
508 	return container_of(attr_set, struct sugov_tunables, attr_set);
509 }
510 
511 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
512 {
513 	struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
514 
515 	return sprintf(buf, "%u\n", tunables->rate_limit_us);
516 }
517 
518 static ssize_t
519 rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
520 {
521 	struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
522 	struct sugov_policy *sg_policy;
523 	unsigned int rate_limit_us;
524 
525 	if (kstrtouint(buf, 10, &rate_limit_us))
526 		return -EINVAL;
527 
528 	tunables->rate_limit_us = rate_limit_us;
529 
530 	list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
531 		sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
532 
533 	return count;
534 }
535 
536 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
537 
538 static struct attribute *sugov_attrs[] = {
539 	&rate_limit_us.attr,
540 	NULL
541 };
542 ATTRIBUTE_GROUPS(sugov);
543 
544 static void sugov_tunables_free(struct kobject *kobj)
545 {
546 	struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
547 
548 	kfree(to_sugov_tunables(attr_set));
549 }
550 
551 static const struct kobj_type sugov_tunables_ktype = {
552 	.default_groups = sugov_groups,
553 	.sysfs_ops = &governor_sysfs_ops,
554 	.release = &sugov_tunables_free,
555 };
556 
557 /********************** cpufreq governor interface *********************/
558 
559 struct cpufreq_governor schedutil_gov;
560 
561 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
562 {
563 	struct sugov_policy *sg_policy;
564 
565 	sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
566 	if (!sg_policy)
567 		return NULL;
568 
569 	sg_policy->policy = policy;
570 	raw_spin_lock_init(&sg_policy->update_lock);
571 	return sg_policy;
572 }
573 
574 static void sugov_policy_free(struct sugov_policy *sg_policy)
575 {
576 	kfree(sg_policy);
577 }
578 
579 static int sugov_kthread_create(struct sugov_policy *sg_policy)
580 {
581 	struct task_struct *thread;
582 	struct sched_attr attr = {
583 		.size		= sizeof(struct sched_attr),
584 		.sched_policy	= SCHED_DEADLINE,
585 		.sched_flags	= SCHED_FLAG_SUGOV,
586 		.sched_nice	= 0,
587 		.sched_priority	= 0,
588 		/*
589 		 * Fake (unused) bandwidth; workaround to "fix"
590 		 * priority inheritance.
591 		 */
592 		.sched_runtime	=  1000000,
593 		.sched_deadline = 10000000,
594 		.sched_period	= 10000000,
595 	};
596 	struct cpufreq_policy *policy = sg_policy->policy;
597 	int ret;
598 
599 	/* kthread only required for slow path */
600 	if (policy->fast_switch_enabled)
601 		return 0;
602 
603 	kthread_init_work(&sg_policy->work, sugov_work);
604 	kthread_init_worker(&sg_policy->worker);
605 	thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
606 				"sugov:%d",
607 				cpumask_first(policy->related_cpus));
608 	if (IS_ERR(thread)) {
609 		pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
610 		return PTR_ERR(thread);
611 	}
612 
613 	ret = sched_setattr_nocheck(thread, &attr);
614 	if (ret) {
615 		kthread_stop(thread);
616 		pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
617 		return ret;
618 	}
619 
620 	sg_policy->thread = thread;
621 	kthread_bind_mask(thread, policy->related_cpus);
622 	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
623 	mutex_init(&sg_policy->work_lock);
624 
625 	wake_up_process(thread);
626 
627 	return 0;
628 }
629 
630 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
631 {
632 	/* kthread only required for slow path */
633 	if (sg_policy->policy->fast_switch_enabled)
634 		return;
635 
636 	kthread_flush_worker(&sg_policy->worker);
637 	kthread_stop(sg_policy->thread);
638 	mutex_destroy(&sg_policy->work_lock);
639 }
640 
641 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
642 {
643 	struct sugov_tunables *tunables;
644 
645 	tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
646 	if (tunables) {
647 		gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
648 		if (!have_governor_per_policy())
649 			global_tunables = tunables;
650 	}
651 	return tunables;
652 }
653 
654 static void sugov_clear_global_tunables(void)
655 {
656 	if (!have_governor_per_policy())
657 		global_tunables = NULL;
658 }
659 
660 static int sugov_init(struct cpufreq_policy *policy)
661 {
662 	struct sugov_policy *sg_policy;
663 	struct sugov_tunables *tunables;
664 	int ret = 0;
665 
666 	/* State should be equivalent to EXIT */
667 	if (policy->governor_data)
668 		return -EBUSY;
669 
670 	cpufreq_enable_fast_switch(policy);
671 
672 	sg_policy = sugov_policy_alloc(policy);
673 	if (!sg_policy) {
674 		ret = -ENOMEM;
675 		goto disable_fast_switch;
676 	}
677 
678 	ret = sugov_kthread_create(sg_policy);
679 	if (ret)
680 		goto free_sg_policy;
681 
682 	mutex_lock(&global_tunables_lock);
683 
684 	if (global_tunables) {
685 		if (WARN_ON(have_governor_per_policy())) {
686 			ret = -EINVAL;
687 			goto stop_kthread;
688 		}
689 		policy->governor_data = sg_policy;
690 		sg_policy->tunables = global_tunables;
691 
692 		gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
693 		goto out;
694 	}
695 
696 	tunables = sugov_tunables_alloc(sg_policy);
697 	if (!tunables) {
698 		ret = -ENOMEM;
699 		goto stop_kthread;
700 	}
701 
702 	tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
703 
704 	policy->governor_data = sg_policy;
705 	sg_policy->tunables = tunables;
706 
707 	ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
708 				   get_governor_parent_kobj(policy), "%s",
709 				   schedutil_gov.name);
710 	if (ret)
711 		goto fail;
712 
713 out:
714 	mutex_unlock(&global_tunables_lock);
715 	return 0;
716 
717 fail:
718 	kobject_put(&tunables->attr_set.kobj);
719 	policy->governor_data = NULL;
720 	sugov_clear_global_tunables();
721 
722 stop_kthread:
723 	sugov_kthread_stop(sg_policy);
724 	mutex_unlock(&global_tunables_lock);
725 
726 free_sg_policy:
727 	sugov_policy_free(sg_policy);
728 
729 disable_fast_switch:
730 	cpufreq_disable_fast_switch(policy);
731 
732 	pr_err("initialization failed (error %d)\n", ret);
733 	return ret;
734 }
735 
736 static void sugov_exit(struct cpufreq_policy *policy)
737 {
738 	struct sugov_policy *sg_policy = policy->governor_data;
739 	struct sugov_tunables *tunables = sg_policy->tunables;
740 	unsigned int count;
741 
742 	mutex_lock(&global_tunables_lock);
743 
744 	count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
745 	policy->governor_data = NULL;
746 	if (!count)
747 		sugov_clear_global_tunables();
748 
749 	mutex_unlock(&global_tunables_lock);
750 
751 	sugov_kthread_stop(sg_policy);
752 	sugov_policy_free(sg_policy);
753 	cpufreq_disable_fast_switch(policy);
754 }
755 
756 static int sugov_start(struct cpufreq_policy *policy)
757 {
758 	struct sugov_policy *sg_policy = policy->governor_data;
759 	void (*uu)(struct update_util_data *data, u64 time, unsigned int flags);
760 	unsigned int cpu;
761 
762 	sg_policy->freq_update_delay_ns	= sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
763 	sg_policy->last_freq_update_time	= 0;
764 	sg_policy->next_freq			= 0;
765 	sg_policy->work_in_progress		= false;
766 	sg_policy->limits_changed		= false;
767 	sg_policy->cached_raw_freq		= 0;
768 
769 	sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
770 
771 	for_each_cpu(cpu, policy->cpus) {
772 		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
773 
774 		memset(sg_cpu, 0, sizeof(*sg_cpu));
775 		sg_cpu->cpu			= cpu;
776 		sg_cpu->sg_policy		= sg_policy;
777 	}
778 
779 	if (policy_is_shared(policy))
780 		uu = sugov_update_shared;
781 	else if (policy->fast_switch_enabled && cpufreq_driver_has_adjust_perf())
782 		uu = sugov_update_single_perf;
783 	else
784 		uu = sugov_update_single_freq;
785 
786 	for_each_cpu(cpu, policy->cpus) {
787 		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
788 
789 		cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, uu);
790 	}
791 	return 0;
792 }
793 
794 static void sugov_stop(struct cpufreq_policy *policy)
795 {
796 	struct sugov_policy *sg_policy = policy->governor_data;
797 	unsigned int cpu;
798 
799 	for_each_cpu(cpu, policy->cpus)
800 		cpufreq_remove_update_util_hook(cpu);
801 
802 	synchronize_rcu();
803 
804 	if (!policy->fast_switch_enabled) {
805 		irq_work_sync(&sg_policy->irq_work);
806 		kthread_cancel_work_sync(&sg_policy->work);
807 	}
808 }
809 
810 static void sugov_limits(struct cpufreq_policy *policy)
811 {
812 	struct sugov_policy *sg_policy = policy->governor_data;
813 
814 	if (!policy->fast_switch_enabled) {
815 		mutex_lock(&sg_policy->work_lock);
816 		cpufreq_policy_apply_limits(policy);
817 		mutex_unlock(&sg_policy->work_lock);
818 	}
819 
820 	sg_policy->limits_changed = true;
821 }
822 
823 struct cpufreq_governor schedutil_gov = {
824 	.name			= "schedutil",
825 	.owner			= THIS_MODULE,
826 	.flags			= CPUFREQ_GOV_DYNAMIC_SWITCHING,
827 	.init			= sugov_init,
828 	.exit			= sugov_exit,
829 	.start			= sugov_start,
830 	.stop			= sugov_stop,
831 	.limits			= sugov_limits,
832 };
833 
834 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
835 struct cpufreq_governor *cpufreq_default_governor(void)
836 {
837 	return &schedutil_gov;
838 }
839 #endif
840 
841 cpufreq_governor_init(schedutil_gov);
842 
843 #ifdef CONFIG_ENERGY_MODEL
844 static void rebuild_sd_workfn(struct work_struct *work)
845 {
846 	rebuild_sched_domains_energy();
847 }
848 static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
849 
850 /*
851  * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
852  * on governor changes to make sure the scheduler knows about it.
853  */
854 void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
855 				  struct cpufreq_governor *old_gov)
856 {
857 	if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
858 		/*
859 		 * When called from the cpufreq_register_driver() path, the
860 		 * cpu_hotplug_lock is already held, so use a work item to
861 		 * avoid nested locking in rebuild_sched_domains().
862 		 */
863 		schedule_work(&rebuild_sd_work);
864 	}
865 
866 }
867 #endif
868