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		bw_dl;
57 	unsigned long		max;
58 
59 	/* The field below is for single-CPU policies only: */
60 #ifdef CONFIG_NO_HZ_COMMON
61 	unsigned long		saved_idle_calls;
62 #endif
63 };
64 
65 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
66 
67 /************************ Governor internals ***********************/
68 
69 static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
70 {
71 	s64 delta_ns;
72 
73 	/*
74 	 * Since cpufreq_update_util() is called with rq->lock held for
75 	 * the @target_cpu, our per-CPU data is fully serialized.
76 	 *
77 	 * However, drivers cannot in general deal with cross-CPU
78 	 * requests, so while get_next_freq() will work, our
79 	 * sugov_update_commit() call may not for the fast switching platforms.
80 	 *
81 	 * Hence stop here for remote requests if they aren't supported
82 	 * by the hardware, as calculating the frequency is pointless if
83 	 * we cannot in fact act on it.
84 	 *
85 	 * For the slow switching platforms, the kthread is always scheduled on
86 	 * the right set of CPUs and any CPU can find the next frequency and
87 	 * schedule the kthread.
88 	 */
89 	if (sg_policy->policy->fast_switch_enabled &&
90 	    !cpufreq_this_cpu_can_update(sg_policy->policy))
91 		return false;
92 
93 	if (unlikely(sg_policy->limits_changed)) {
94 		sg_policy->limits_changed = false;
95 		sg_policy->need_freq_update = true;
96 		return true;
97 	}
98 
99 	delta_ns = time - sg_policy->last_freq_update_time;
100 
101 	return delta_ns >= sg_policy->freq_update_delay_ns;
102 }
103 
104 static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
105 				   unsigned int next_freq)
106 {
107 	if (sg_policy->next_freq == next_freq)
108 		return false;
109 
110 	sg_policy->next_freq = next_freq;
111 	sg_policy->last_freq_update_time = time;
112 
113 	return true;
114 }
115 
116 static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
117 			      unsigned int next_freq)
118 {
119 	struct cpufreq_policy *policy = sg_policy->policy;
120 	int cpu;
121 
122 	if (!sugov_update_next_freq(sg_policy, time, next_freq))
123 		return;
124 
125 	next_freq = cpufreq_driver_fast_switch(policy, next_freq);
126 	if (!next_freq)
127 		return;
128 
129 	policy->cur = next_freq;
130 
131 	if (trace_cpu_frequency_enabled()) {
132 		for_each_cpu(cpu, policy->cpus)
133 			trace_cpu_frequency(next_freq, cpu);
134 	}
135 }
136 
137 static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
138 				  unsigned int next_freq)
139 {
140 	if (!sugov_update_next_freq(sg_policy, time, next_freq))
141 		return;
142 
143 	if (!sg_policy->work_in_progress) {
144 		sg_policy->work_in_progress = true;
145 		irq_work_queue(&sg_policy->irq_work);
146 	}
147 }
148 
149 /**
150  * get_next_freq - Compute a new frequency for a given cpufreq policy.
151  * @sg_policy: schedutil policy object to compute the new frequency for.
152  * @util: Current CPU utilization.
153  * @max: CPU capacity.
154  *
155  * If the utilization is frequency-invariant, choose the new frequency to be
156  * proportional to it, that is
157  *
158  * next_freq = C * max_freq * util / max
159  *
160  * Otherwise, approximate the would-be frequency-invariant utilization by
161  * util_raw * (curr_freq / max_freq) which leads to
162  *
163  * next_freq = C * curr_freq * util_raw / max
164  *
165  * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
166  *
167  * The lowest driver-supported frequency which is equal or greater than the raw
168  * next_freq (as calculated above) is returned, subject to policy min/max and
169  * cpufreq driver limitations.
170  */
171 static unsigned int get_next_freq(struct sugov_policy *sg_policy,
172 				  unsigned long util, unsigned long max)
173 {
174 	struct cpufreq_policy *policy = sg_policy->policy;
175 	unsigned int freq = arch_scale_freq_invariant() ?
176 				policy->cpuinfo.max_freq : policy->cur;
177 
178 	freq = map_util_freq(util, freq, max);
179 
180 	if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
181 		return sg_policy->next_freq;
182 
183 	sg_policy->need_freq_update = false;
184 	sg_policy->cached_raw_freq = freq;
185 	return cpufreq_driver_resolve_freq(policy, freq);
186 }
187 
188 /*
189  * This function computes an effective utilization for the given CPU, to be
190  * used for frequency selection given the linear relation: f = u * f_max.
191  *
192  * The scheduler tracks the following metrics:
193  *
194  *   cpu_util_{cfs,rt,dl,irq}()
195  *   cpu_bw_dl()
196  *
197  * Where the cfs,rt and dl util numbers are tracked with the same metric and
198  * synchronized windows and are thus directly comparable.
199  *
200  * The cfs,rt,dl utilization are the running times measured with rq->clock_task
201  * which excludes things like IRQ and steal-time. These latter are then accrued
202  * in the irq utilization.
203  *
204  * The DL bandwidth number otoh is not a measured metric but a value computed
205  * based on the task model parameters and gives the minimal utilization
206  * required to meet deadlines.
207  */
208 unsigned long schedutil_cpu_util(int cpu, unsigned long util_cfs,
209 				 unsigned long max, enum schedutil_type type,
210 				 struct task_struct *p)
211 {
212 	unsigned long dl_util, util, irq;
213 	struct rq *rq = cpu_rq(cpu);
214 
215 	if (!IS_BUILTIN(CONFIG_UCLAMP_TASK) &&
216 	    type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
217 		return max;
218 	}
219 
220 	/*
221 	 * Early check to see if IRQ/steal time saturates the CPU, can be
222 	 * because of inaccuracies in how we track these -- see
223 	 * update_irq_load_avg().
224 	 */
225 	irq = cpu_util_irq(rq);
226 	if (unlikely(irq >= max))
227 		return max;
228 
229 	/*
230 	 * Because the time spend on RT/DL tasks is visible as 'lost' time to
231 	 * CFS tasks and we use the same metric to track the effective
232 	 * utilization (PELT windows are synchronized) we can directly add them
233 	 * to obtain the CPU's actual utilization.
234 	 *
235 	 * CFS and RT utilization can be boosted or capped, depending on
236 	 * utilization clamp constraints requested by currently RUNNABLE
237 	 * tasks.
238 	 * When there are no CFS RUNNABLE tasks, clamps are released and
239 	 * frequency will be gracefully reduced with the utilization decay.
240 	 */
241 	util = util_cfs + cpu_util_rt(rq);
242 	if (type == FREQUENCY_UTIL)
243 		util = uclamp_util_with(rq, util, p);
244 
245 	dl_util = cpu_util_dl(rq);
246 
247 	/*
248 	 * For frequency selection we do not make cpu_util_dl() a permanent part
249 	 * of this sum because we want to use cpu_bw_dl() later on, but we need
250 	 * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
251 	 * that we select f_max when there is no idle time.
252 	 *
253 	 * NOTE: numerical errors or stop class might cause us to not quite hit
254 	 * saturation when we should -- something for later.
255 	 */
256 	if (util + dl_util >= max)
257 		return max;
258 
259 	/*
260 	 * OTOH, for energy computation we need the estimated running time, so
261 	 * include util_dl and ignore dl_bw.
262 	 */
263 	if (type == ENERGY_UTIL)
264 		util += dl_util;
265 
266 	/*
267 	 * There is still idle time; further improve the number by using the
268 	 * irq metric. Because IRQ/steal time is hidden from the task clock we
269 	 * need to scale the task numbers:
270 	 *
271 	 *              max - irq
272 	 *   U' = irq + --------- * U
273 	 *                 max
274 	 */
275 	util = scale_irq_capacity(util, irq, max);
276 	util += irq;
277 
278 	/*
279 	 * Bandwidth required by DEADLINE must always be granted while, for
280 	 * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
281 	 * to gracefully reduce the frequency when no tasks show up for longer
282 	 * periods of time.
283 	 *
284 	 * Ideally we would like to set bw_dl as min/guaranteed freq and util +
285 	 * bw_dl as requested freq. However, cpufreq is not yet ready for such
286 	 * an interface. So, we only do the latter for now.
287 	 */
288 	if (type == FREQUENCY_UTIL)
289 		util += cpu_bw_dl(rq);
290 
291 	return min(max, util);
292 }
293 
294 static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)
295 {
296 	struct rq *rq = cpu_rq(sg_cpu->cpu);
297 	unsigned long util = cpu_util_cfs(rq);
298 	unsigned long max = arch_scale_cpu_capacity(sg_cpu->cpu);
299 
300 	sg_cpu->max = max;
301 	sg_cpu->bw_dl = cpu_bw_dl(rq);
302 
303 	return schedutil_cpu_util(sg_cpu->cpu, util, max, FREQUENCY_UTIL, NULL);
304 }
305 
306 /**
307  * sugov_iowait_reset() - Reset the IO boost status of a CPU.
308  * @sg_cpu: the sugov data for the CPU to boost
309  * @time: the update time from the caller
310  * @set_iowait_boost: true if an IO boost has been requested
311  *
312  * The IO wait boost of a task is disabled after a tick since the last update
313  * of a CPU. If a new IO wait boost is requested after more then a tick, then
314  * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
315  * efficiency by ignoring sporadic wakeups from IO.
316  */
317 static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
318 			       bool set_iowait_boost)
319 {
320 	s64 delta_ns = time - sg_cpu->last_update;
321 
322 	/* Reset boost only if a tick has elapsed since last request */
323 	if (delta_ns <= TICK_NSEC)
324 		return false;
325 
326 	sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
327 	sg_cpu->iowait_boost_pending = set_iowait_boost;
328 
329 	return true;
330 }
331 
332 /**
333  * sugov_iowait_boost() - Updates the IO boost status of a CPU.
334  * @sg_cpu: the sugov data for the CPU to boost
335  * @time: the update time from the caller
336  * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
337  *
338  * Each time a task wakes up after an IO operation, the CPU utilization can be
339  * boosted to a certain utilization which doubles at each "frequent and
340  * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
341  * of the maximum OPP.
342  *
343  * To keep doubling, an IO boost has to be requested at least once per tick,
344  * otherwise we restart from the utilization of the minimum OPP.
345  */
346 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
347 			       unsigned int flags)
348 {
349 	bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
350 
351 	/* Reset boost if the CPU appears to have been idle enough */
352 	if (sg_cpu->iowait_boost &&
353 	    sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
354 		return;
355 
356 	/* Boost only tasks waking up after IO */
357 	if (!set_iowait_boost)
358 		return;
359 
360 	/* Ensure boost doubles only one time at each request */
361 	if (sg_cpu->iowait_boost_pending)
362 		return;
363 	sg_cpu->iowait_boost_pending = true;
364 
365 	/* Double the boost at each request */
366 	if (sg_cpu->iowait_boost) {
367 		sg_cpu->iowait_boost =
368 			min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
369 		return;
370 	}
371 
372 	/* First wakeup after IO: start with minimum boost */
373 	sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
374 }
375 
376 /**
377  * sugov_iowait_apply() - Apply the IO boost to a CPU.
378  * @sg_cpu: the sugov data for the cpu to boost
379  * @time: the update time from the caller
380  * @util: the utilization to (eventually) boost
381  * @max: the maximum value the utilization can be boosted to
382  *
383  * A CPU running a task which woken up after an IO operation can have its
384  * utilization boosted to speed up the completion of those IO operations.
385  * The IO boost value is increased each time a task wakes up from IO, in
386  * sugov_iowait_apply(), and it's instead decreased by this function,
387  * each time an increase has not been requested (!iowait_boost_pending).
388  *
389  * A CPU which also appears to have been idle for at least one tick has also
390  * its IO boost utilization reset.
391  *
392  * This mechanism is designed to boost high frequently IO waiting tasks, while
393  * being more conservative on tasks which does sporadic IO operations.
394  */
395 static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
396 					unsigned long util, unsigned long max)
397 {
398 	unsigned long boost;
399 
400 	/* No boost currently required */
401 	if (!sg_cpu->iowait_boost)
402 		return util;
403 
404 	/* Reset boost if the CPU appears to have been idle enough */
405 	if (sugov_iowait_reset(sg_cpu, time, false))
406 		return util;
407 
408 	if (!sg_cpu->iowait_boost_pending) {
409 		/*
410 		 * No boost pending; reduce the boost value.
411 		 */
412 		sg_cpu->iowait_boost >>= 1;
413 		if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
414 			sg_cpu->iowait_boost = 0;
415 			return util;
416 		}
417 	}
418 
419 	sg_cpu->iowait_boost_pending = false;
420 
421 	/*
422 	 * @util is already in capacity scale; convert iowait_boost
423 	 * into the same scale so we can compare.
424 	 */
425 	boost = (sg_cpu->iowait_boost * max) >> SCHED_CAPACITY_SHIFT;
426 	return max(boost, util);
427 }
428 
429 #ifdef CONFIG_NO_HZ_COMMON
430 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
431 {
432 	unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
433 	bool ret = idle_calls == sg_cpu->saved_idle_calls;
434 
435 	sg_cpu->saved_idle_calls = idle_calls;
436 	return ret;
437 }
438 #else
439 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
440 #endif /* CONFIG_NO_HZ_COMMON */
441 
442 /*
443  * Make sugov_should_update_freq() ignore the rate limit when DL
444  * has increased the utilization.
445  */
446 static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
447 {
448 	if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
449 		sg_policy->limits_changed = true;
450 }
451 
452 static void sugov_update_single(struct update_util_data *hook, u64 time,
453 				unsigned int flags)
454 {
455 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
456 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
457 	unsigned long util, max;
458 	unsigned int next_f;
459 	bool busy;
460 
461 	sugov_iowait_boost(sg_cpu, time, flags);
462 	sg_cpu->last_update = time;
463 
464 	ignore_dl_rate_limit(sg_cpu, sg_policy);
465 
466 	if (!sugov_should_update_freq(sg_policy, time))
467 		return;
468 
469 	/* Limits may have changed, don't skip frequency update */
470 	busy = !sg_policy->need_freq_update && sugov_cpu_is_busy(sg_cpu);
471 
472 	util = sugov_get_util(sg_cpu);
473 	max = sg_cpu->max;
474 	util = sugov_iowait_apply(sg_cpu, time, util, max);
475 	next_f = get_next_freq(sg_policy, util, max);
476 	/*
477 	 * Do not reduce the frequency if the CPU has not been idle
478 	 * recently, as the reduction is likely to be premature then.
479 	 */
480 	if (busy && next_f < sg_policy->next_freq) {
481 		next_f = sg_policy->next_freq;
482 
483 		/* Reset cached freq as next_freq has changed */
484 		sg_policy->cached_raw_freq = 0;
485 	}
486 
487 	/*
488 	 * This code runs under rq->lock for the target CPU, so it won't run
489 	 * concurrently on two different CPUs for the same target and it is not
490 	 * necessary to acquire the lock in the fast switch case.
491 	 */
492 	if (sg_policy->policy->fast_switch_enabled) {
493 		sugov_fast_switch(sg_policy, time, next_f);
494 	} else {
495 		raw_spin_lock(&sg_policy->update_lock);
496 		sugov_deferred_update(sg_policy, time, next_f);
497 		raw_spin_unlock(&sg_policy->update_lock);
498 	}
499 }
500 
501 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
502 {
503 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
504 	struct cpufreq_policy *policy = sg_policy->policy;
505 	unsigned long util = 0, max = 1;
506 	unsigned int j;
507 
508 	for_each_cpu(j, policy->cpus) {
509 		struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
510 		unsigned long j_util, j_max;
511 
512 		j_util = sugov_get_util(j_sg_cpu);
513 		j_max = j_sg_cpu->max;
514 		j_util = sugov_iowait_apply(j_sg_cpu, time, j_util, j_max);
515 
516 		if (j_util * max > j_max * util) {
517 			util = j_util;
518 			max = j_max;
519 		}
520 	}
521 
522 	return get_next_freq(sg_policy, util, max);
523 }
524 
525 static void
526 sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
527 {
528 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
529 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
530 	unsigned int next_f;
531 
532 	raw_spin_lock(&sg_policy->update_lock);
533 
534 	sugov_iowait_boost(sg_cpu, time, flags);
535 	sg_cpu->last_update = time;
536 
537 	ignore_dl_rate_limit(sg_cpu, sg_policy);
538 
539 	if (sugov_should_update_freq(sg_policy, time)) {
540 		next_f = sugov_next_freq_shared(sg_cpu, time);
541 
542 		if (sg_policy->policy->fast_switch_enabled)
543 			sugov_fast_switch(sg_policy, time, next_f);
544 		else
545 			sugov_deferred_update(sg_policy, time, next_f);
546 	}
547 
548 	raw_spin_unlock(&sg_policy->update_lock);
549 }
550 
551 static void sugov_work(struct kthread_work *work)
552 {
553 	struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
554 	unsigned int freq;
555 	unsigned long flags;
556 
557 	/*
558 	 * Hold sg_policy->update_lock shortly to handle the case where:
559 	 * incase sg_policy->next_freq is read here, and then updated by
560 	 * sugov_deferred_update() just before work_in_progress is set to false
561 	 * here, we may miss queueing the new update.
562 	 *
563 	 * Note: If a work was queued after the update_lock is released,
564 	 * sugov_work() will just be called again by kthread_work code; and the
565 	 * request will be proceed before the sugov thread sleeps.
566 	 */
567 	raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
568 	freq = sg_policy->next_freq;
569 	sg_policy->work_in_progress = false;
570 	raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
571 
572 	mutex_lock(&sg_policy->work_lock);
573 	__cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
574 	mutex_unlock(&sg_policy->work_lock);
575 }
576 
577 static void sugov_irq_work(struct irq_work *irq_work)
578 {
579 	struct sugov_policy *sg_policy;
580 
581 	sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
582 
583 	kthread_queue_work(&sg_policy->worker, &sg_policy->work);
584 }
585 
586 /************************** sysfs interface ************************/
587 
588 static struct sugov_tunables *global_tunables;
589 static DEFINE_MUTEX(global_tunables_lock);
590 
591 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
592 {
593 	return container_of(attr_set, struct sugov_tunables, attr_set);
594 }
595 
596 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
597 {
598 	struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
599 
600 	return sprintf(buf, "%u\n", tunables->rate_limit_us);
601 }
602 
603 static ssize_t
604 rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
605 {
606 	struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
607 	struct sugov_policy *sg_policy;
608 	unsigned int rate_limit_us;
609 
610 	if (kstrtouint(buf, 10, &rate_limit_us))
611 		return -EINVAL;
612 
613 	tunables->rate_limit_us = rate_limit_us;
614 
615 	list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
616 		sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
617 
618 	return count;
619 }
620 
621 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
622 
623 static struct attribute *sugov_attrs[] = {
624 	&rate_limit_us.attr,
625 	NULL
626 };
627 ATTRIBUTE_GROUPS(sugov);
628 
629 static struct kobj_type sugov_tunables_ktype = {
630 	.default_groups = sugov_groups,
631 	.sysfs_ops = &governor_sysfs_ops,
632 };
633 
634 /********************** cpufreq governor interface *********************/
635 
636 struct cpufreq_governor schedutil_gov;
637 
638 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
639 {
640 	struct sugov_policy *sg_policy;
641 
642 	sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
643 	if (!sg_policy)
644 		return NULL;
645 
646 	sg_policy->policy = policy;
647 	raw_spin_lock_init(&sg_policy->update_lock);
648 	return sg_policy;
649 }
650 
651 static void sugov_policy_free(struct sugov_policy *sg_policy)
652 {
653 	kfree(sg_policy);
654 }
655 
656 static int sugov_kthread_create(struct sugov_policy *sg_policy)
657 {
658 	struct task_struct *thread;
659 	struct sched_attr attr = {
660 		.size		= sizeof(struct sched_attr),
661 		.sched_policy	= SCHED_DEADLINE,
662 		.sched_flags	= SCHED_FLAG_SUGOV,
663 		.sched_nice	= 0,
664 		.sched_priority	= 0,
665 		/*
666 		 * Fake (unused) bandwidth; workaround to "fix"
667 		 * priority inheritance.
668 		 */
669 		.sched_runtime	=  1000000,
670 		.sched_deadline = 10000000,
671 		.sched_period	= 10000000,
672 	};
673 	struct cpufreq_policy *policy = sg_policy->policy;
674 	int ret;
675 
676 	/* kthread only required for slow path */
677 	if (policy->fast_switch_enabled)
678 		return 0;
679 
680 	kthread_init_work(&sg_policy->work, sugov_work);
681 	kthread_init_worker(&sg_policy->worker);
682 	thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
683 				"sugov:%d",
684 				cpumask_first(policy->related_cpus));
685 	if (IS_ERR(thread)) {
686 		pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
687 		return PTR_ERR(thread);
688 	}
689 
690 	ret = sched_setattr_nocheck(thread, &attr);
691 	if (ret) {
692 		kthread_stop(thread);
693 		pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
694 		return ret;
695 	}
696 
697 	sg_policy->thread = thread;
698 	kthread_bind_mask(thread, policy->related_cpus);
699 	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
700 	mutex_init(&sg_policy->work_lock);
701 
702 	wake_up_process(thread);
703 
704 	return 0;
705 }
706 
707 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
708 {
709 	/* kthread only required for slow path */
710 	if (sg_policy->policy->fast_switch_enabled)
711 		return;
712 
713 	kthread_flush_worker(&sg_policy->worker);
714 	kthread_stop(sg_policy->thread);
715 	mutex_destroy(&sg_policy->work_lock);
716 }
717 
718 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
719 {
720 	struct sugov_tunables *tunables;
721 
722 	tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
723 	if (tunables) {
724 		gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
725 		if (!have_governor_per_policy())
726 			global_tunables = tunables;
727 	}
728 	return tunables;
729 }
730 
731 static void sugov_tunables_free(struct sugov_tunables *tunables)
732 {
733 	if (!have_governor_per_policy())
734 		global_tunables = NULL;
735 
736 	kfree(tunables);
737 }
738 
739 static int sugov_init(struct cpufreq_policy *policy)
740 {
741 	struct sugov_policy *sg_policy;
742 	struct sugov_tunables *tunables;
743 	int ret = 0;
744 
745 	/* State should be equivalent to EXIT */
746 	if (policy->governor_data)
747 		return -EBUSY;
748 
749 	cpufreq_enable_fast_switch(policy);
750 
751 	sg_policy = sugov_policy_alloc(policy);
752 	if (!sg_policy) {
753 		ret = -ENOMEM;
754 		goto disable_fast_switch;
755 	}
756 
757 	ret = sugov_kthread_create(sg_policy);
758 	if (ret)
759 		goto free_sg_policy;
760 
761 	mutex_lock(&global_tunables_lock);
762 
763 	if (global_tunables) {
764 		if (WARN_ON(have_governor_per_policy())) {
765 			ret = -EINVAL;
766 			goto stop_kthread;
767 		}
768 		policy->governor_data = sg_policy;
769 		sg_policy->tunables = global_tunables;
770 
771 		gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
772 		goto out;
773 	}
774 
775 	tunables = sugov_tunables_alloc(sg_policy);
776 	if (!tunables) {
777 		ret = -ENOMEM;
778 		goto stop_kthread;
779 	}
780 
781 	tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
782 
783 	policy->governor_data = sg_policy;
784 	sg_policy->tunables = tunables;
785 
786 	ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
787 				   get_governor_parent_kobj(policy), "%s",
788 				   schedutil_gov.name);
789 	if (ret)
790 		goto fail;
791 
792 out:
793 	mutex_unlock(&global_tunables_lock);
794 	return 0;
795 
796 fail:
797 	kobject_put(&tunables->attr_set.kobj);
798 	policy->governor_data = NULL;
799 	sugov_tunables_free(tunables);
800 
801 stop_kthread:
802 	sugov_kthread_stop(sg_policy);
803 	mutex_unlock(&global_tunables_lock);
804 
805 free_sg_policy:
806 	sugov_policy_free(sg_policy);
807 
808 disable_fast_switch:
809 	cpufreq_disable_fast_switch(policy);
810 
811 	pr_err("initialization failed (error %d)\n", ret);
812 	return ret;
813 }
814 
815 static void sugov_exit(struct cpufreq_policy *policy)
816 {
817 	struct sugov_policy *sg_policy = policy->governor_data;
818 	struct sugov_tunables *tunables = sg_policy->tunables;
819 	unsigned int count;
820 
821 	mutex_lock(&global_tunables_lock);
822 
823 	count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
824 	policy->governor_data = NULL;
825 	if (!count)
826 		sugov_tunables_free(tunables);
827 
828 	mutex_unlock(&global_tunables_lock);
829 
830 	sugov_kthread_stop(sg_policy);
831 	sugov_policy_free(sg_policy);
832 	cpufreq_disable_fast_switch(policy);
833 }
834 
835 static int sugov_start(struct cpufreq_policy *policy)
836 {
837 	struct sugov_policy *sg_policy = policy->governor_data;
838 	unsigned int cpu;
839 
840 	sg_policy->freq_update_delay_ns	= sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
841 	sg_policy->last_freq_update_time	= 0;
842 	sg_policy->next_freq			= 0;
843 	sg_policy->work_in_progress		= false;
844 	sg_policy->limits_changed		= false;
845 	sg_policy->need_freq_update		= false;
846 	sg_policy->cached_raw_freq		= 0;
847 
848 	for_each_cpu(cpu, policy->cpus) {
849 		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
850 
851 		memset(sg_cpu, 0, sizeof(*sg_cpu));
852 		sg_cpu->cpu			= cpu;
853 		sg_cpu->sg_policy		= sg_policy;
854 	}
855 
856 	for_each_cpu(cpu, policy->cpus) {
857 		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
858 
859 		cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
860 					     policy_is_shared(policy) ?
861 							sugov_update_shared :
862 							sugov_update_single);
863 	}
864 	return 0;
865 }
866 
867 static void sugov_stop(struct cpufreq_policy *policy)
868 {
869 	struct sugov_policy *sg_policy = policy->governor_data;
870 	unsigned int cpu;
871 
872 	for_each_cpu(cpu, policy->cpus)
873 		cpufreq_remove_update_util_hook(cpu);
874 
875 	synchronize_rcu();
876 
877 	if (!policy->fast_switch_enabled) {
878 		irq_work_sync(&sg_policy->irq_work);
879 		kthread_cancel_work_sync(&sg_policy->work);
880 	}
881 }
882 
883 static void sugov_limits(struct cpufreq_policy *policy)
884 {
885 	struct sugov_policy *sg_policy = policy->governor_data;
886 
887 	if (!policy->fast_switch_enabled) {
888 		mutex_lock(&sg_policy->work_lock);
889 		cpufreq_policy_apply_limits(policy);
890 		mutex_unlock(&sg_policy->work_lock);
891 	}
892 
893 	sg_policy->limits_changed = true;
894 }
895 
896 struct cpufreq_governor schedutil_gov = {
897 	.name			= "schedutil",
898 	.owner			= THIS_MODULE,
899 	.dynamic_switching	= true,
900 	.init			= sugov_init,
901 	.exit			= sugov_exit,
902 	.start			= sugov_start,
903 	.stop			= sugov_stop,
904 	.limits			= sugov_limits,
905 };
906 
907 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
908 struct cpufreq_governor *cpufreq_default_governor(void)
909 {
910 	return &schedutil_gov;
911 }
912 #endif
913 
914 static int __init sugov_register(void)
915 {
916 	return cpufreq_register_governor(&schedutil_gov);
917 }
918 fs_initcall(sugov_register);
919 
920 #ifdef CONFIG_ENERGY_MODEL
921 extern bool sched_energy_update;
922 extern struct mutex sched_energy_mutex;
923 
924 static void rebuild_sd_workfn(struct work_struct *work)
925 {
926 	mutex_lock(&sched_energy_mutex);
927 	sched_energy_update = true;
928 	rebuild_sched_domains();
929 	sched_energy_update = false;
930 	mutex_unlock(&sched_energy_mutex);
931 }
932 static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
933 
934 /*
935  * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
936  * on governor changes to make sure the scheduler knows about it.
937  */
938 void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
939 				  struct cpufreq_governor *old_gov)
940 {
941 	if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
942 		/*
943 		 * When called from the cpufreq_register_driver() path, the
944 		 * cpu_hotplug_lock is already held, so use a work item to
945 		 * avoid nested locking in rebuild_sched_domains().
946 		 */
947 		schedule_work(&rebuild_sd_work);
948 	}
949 
950 }
951 #endif
952