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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Power Management Quality of Service (PM QoS) support base.
4 *
5 * Copyright (C) 2020 Intel Corporation
6 *
7 * Authors:
8 * Mark Gross <[email protected]>
9 * Rafael J. Wysocki <[email protected]>
10 *
11 * Provided here is an interface for specifying PM QoS dependencies. It allows
12 * entities depending on QoS constraints to register their requests which are
13 * aggregated as appropriate to produce effective constraints (target values)
14 * that can be monitored by entities needing to respect them, either by polling
15 * or through a built-in notification mechanism.
16 *
17 * In addition to the basic functionality, more specific interfaces for managing
18 * global CPU latency QoS requests and frequency QoS requests are provided.
19 */
20
21/*#define DEBUG*/
22
23#include <linux/pm_qos.h>
24#include <linux/sched.h>
25#include <linux/spinlock.h>
26#include <linux/slab.h>
27#include <linux/time.h>
28#include <linux/fs.h>
29#include <linux/device.h>
30#include <linux/miscdevice.h>
31#include <linux/string.h>
32#include <linux/platform_device.h>
33#include <linux/init.h>
34#include <linux/kernel.h>
35#include <linux/debugfs.h>
36#include <linux/seq_file.h>
37
38#include <linux/uaccess.h>
39#include <linux/export.h>
40#include <trace/events/power.h>
41
42/*
43 * locking rule: all changes to constraints or notifiers lists
44 * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
45 * held, taken with _irqsave. One lock to rule them all
46 */
47static DEFINE_SPINLOCK(pm_qos_lock);
48
49/**
50 * pm_qos_read_value - Return the current effective constraint value.
51 * @c: List of PM QoS constraint requests.
52 */
53s32 pm_qos_read_value(struct pm_qos_constraints *c)
54{
55 return READ_ONCE(c->target_value);
56}
57
58static int pm_qos_get_value(struct pm_qos_constraints *c)
59{
60 if (plist_head_empty(&c->list))
61 return c->no_constraint_value;
62
63 switch (c->type) {
64 case PM_QOS_MIN:
65 return plist_first(&c->list)->prio;
66
67 case PM_QOS_MAX:
68 return plist_last(&c->list)->prio;
69
70 default:
71 WARN(1, "Unknown PM QoS type in %s\n", __func__);
72 return PM_QOS_DEFAULT_VALUE;
73 }
74}
75
76static void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
77{
78 WRITE_ONCE(c->target_value, value);
79}
80
81/**
82 * pm_qos_update_target - Update a list of PM QoS constraint requests.
83 * @c: List of PM QoS requests.
84 * @node: Target list entry.
85 * @action: Action to carry out (add, update or remove).
86 * @value: New request value for the target list entry.
87 *
88 * Update the given list of PM QoS constraint requests, @c, by carrying an
89 * @action involving the @node list entry and @value on it.
90 *
91 * The recognized values of @action are PM_QOS_ADD_REQ (store @value in @node
92 * and add it to the list), PM_QOS_UPDATE_REQ (remove @node from the list, store
93 * @value in it and add it to the list again), and PM_QOS_REMOVE_REQ (remove
94 * @node from the list, ignore @value).
95 *
96 * Return: 1 if the aggregate constraint value has changed, 0 otherwise.
97 */
98int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
99 enum pm_qos_req_action action, int value)
100{
101 int prev_value, curr_value, new_value;
102 unsigned long flags;
103
104 spin_lock_irqsave(&pm_qos_lock, flags);
105
106 prev_value = pm_qos_get_value(c);
107 if (value == PM_QOS_DEFAULT_VALUE)
108 new_value = c->default_value;
109 else
110 new_value = value;
111
112 switch (action) {
113 case PM_QOS_REMOVE_REQ:
114 plist_del(node, &c->list);
115 break;
116 case PM_QOS_UPDATE_REQ:
117 /*
118 * To change the list, atomically remove, reinit with new value
119 * and add, then see if the aggregate has changed.
120 */
121 plist_del(node, &c->list);
122 fallthrough;
123 case PM_QOS_ADD_REQ:
124 plist_node_init(node, new_value);
125 plist_add(node, &c->list);
126 break;
127 default:
128 /* no action */
129 ;
130 }
131
132 curr_value = pm_qos_get_value(c);
133 pm_qos_set_value(c, curr_value);
134
135 spin_unlock_irqrestore(&pm_qos_lock, flags);
136
137 trace_pm_qos_update_target(action, prev_value, curr_value);
138
139 if (prev_value == curr_value)
140 return 0;
141
142 if (c->notifiers)
143 blocking_notifier_call_chain(c->notifiers, curr_value, NULL);
144
145 return 1;
146}
147
148/**
149 * pm_qos_flags_remove_req - Remove device PM QoS flags request.
150 * @pqf: Device PM QoS flags set to remove the request from.
151 * @req: Request to remove from the set.
152 */
153static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
154 struct pm_qos_flags_request *req)
155{
156 s32 val = 0;
157
158 list_del(&req->node);
159 list_for_each_entry(req, &pqf->list, node)
160 val |= req->flags;
161
162 pqf->effective_flags = val;
163}
164
165/**
166 * pm_qos_update_flags - Update a set of PM QoS flags.
167 * @pqf: Set of PM QoS flags to update.
168 * @req: Request to add to the set, to modify, or to remove from the set.
169 * @action: Action to take on the set.
170 * @val: Value of the request to add or modify.
171 *
172 * Return: 1 if the aggregate constraint value has changed, 0 otherwise.
173 */
174bool pm_qos_update_flags(struct pm_qos_flags *pqf,
175 struct pm_qos_flags_request *req,
176 enum pm_qos_req_action action, s32 val)
177{
178 unsigned long irqflags;
179 s32 prev_value, curr_value;
180
181 spin_lock_irqsave(&pm_qos_lock, irqflags);
182
183 prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
184
185 switch (action) {
186 case PM_QOS_REMOVE_REQ:
187 pm_qos_flags_remove_req(pqf, req);
188 break;
189 case PM_QOS_UPDATE_REQ:
190 pm_qos_flags_remove_req(pqf, req);
191 fallthrough;
192 case PM_QOS_ADD_REQ:
193 req->flags = val;
194 INIT_LIST_HEAD(&req->node);
195 list_add_tail(&req->node, &pqf->list);
196 pqf->effective_flags |= val;
197 break;
198 default:
199 /* no action */
200 ;
201 }
202
203 curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
204
205 spin_unlock_irqrestore(&pm_qos_lock, irqflags);
206
207 trace_pm_qos_update_flags(action, prev_value, curr_value);
208
209 return prev_value != curr_value;
210}
211
212#ifdef CONFIG_CPU_IDLE
213/* Definitions related to the CPU latency QoS. */
214
215static struct pm_qos_constraints cpu_latency_constraints = {
216 .list = PLIST_HEAD_INIT(cpu_latency_constraints.list),
217 .target_value = PM_QOS_CPU_LATENCY_DEFAULT_VALUE,
218 .default_value = PM_QOS_CPU_LATENCY_DEFAULT_VALUE,
219 .no_constraint_value = PM_QOS_CPU_LATENCY_DEFAULT_VALUE,
220 .type = PM_QOS_MIN,
221};
222
223static inline bool cpu_latency_qos_value_invalid(s32 value)
224{
225 return value < 0 && value != PM_QOS_DEFAULT_VALUE;
226}
227
228/**
229 * cpu_latency_qos_limit - Return current system-wide CPU latency QoS limit.
230 */
231s32 cpu_latency_qos_limit(void)
232{
233 return pm_qos_read_value(&cpu_latency_constraints);
234}
235
236/**
237 * cpu_latency_qos_request_active - Check the given PM QoS request.
238 * @req: PM QoS request to check.
239 *
240 * Return: 'true' if @req has been added to the CPU latency QoS list, 'false'
241 * otherwise.
242 */
243bool cpu_latency_qos_request_active(struct pm_qos_request *req)
244{
245 return req->qos == &cpu_latency_constraints;
246}
247EXPORT_SYMBOL_GPL(cpu_latency_qos_request_active);
248
249static void cpu_latency_qos_apply(struct pm_qos_request *req,
250 enum pm_qos_req_action action, s32 value)
251{
252 int ret = pm_qos_update_target(req->qos, &req->node, action, value);
253 if (ret > 0)
254 wake_up_all_idle_cpus();
255}
256
257/**
258 * cpu_latency_qos_add_request - Add new CPU latency QoS request.
259 * @req: Pointer to a preallocated handle.
260 * @value: Requested constraint value.
261 *
262 * Use @value to initialize the request handle pointed to by @req, insert it as
263 * a new entry to the CPU latency QoS list and recompute the effective QoS
264 * constraint for that list.
265 *
266 * Callers need to save the handle for later use in updates and removal of the
267 * QoS request represented by it.
268 */
269void cpu_latency_qos_add_request(struct pm_qos_request *req, s32 value)
270{
271 if (!req || cpu_latency_qos_value_invalid(value))
272 return;
273
274 if (cpu_latency_qos_request_active(req)) {
275 WARN(1, KERN_ERR "%s called for already added request\n", __func__);
276 return;
277 }
278
279 trace_pm_qos_add_request(value);
280
281 req->qos = &cpu_latency_constraints;
282 cpu_latency_qos_apply(req, PM_QOS_ADD_REQ, value);
283}
284EXPORT_SYMBOL_GPL(cpu_latency_qos_add_request);
285
286/**
287 * cpu_latency_qos_update_request - Modify existing CPU latency QoS request.
288 * @req : QoS request to update.
289 * @new_value: New requested constraint value.
290 *
291 * Use @new_value to update the QoS request represented by @req in the CPU
292 * latency QoS list along with updating the effective constraint value for that
293 * list.
294 */
295void cpu_latency_qos_update_request(struct pm_qos_request *req, s32 new_value)
296{
297 if (!req || cpu_latency_qos_value_invalid(new_value))
298 return;
299
300 if (!cpu_latency_qos_request_active(req)) {
301 WARN(1, KERN_ERR "%s called for unknown object\n", __func__);
302 return;
303 }
304
305 trace_pm_qos_update_request(new_value);
306
307 if (new_value == req->node.prio)
308 return;
309
310 cpu_latency_qos_apply(req, PM_QOS_UPDATE_REQ, new_value);
311}
312EXPORT_SYMBOL_GPL(cpu_latency_qos_update_request);
313
314/**
315 * cpu_latency_qos_remove_request - Remove existing CPU latency QoS request.
316 * @req: QoS request to remove.
317 *
318 * Remove the CPU latency QoS request represented by @req from the CPU latency
319 * QoS list along with updating the effective constraint value for that list.
320 */
321void cpu_latency_qos_remove_request(struct pm_qos_request *req)
322{
323 if (!req)
324 return;
325
326 if (!cpu_latency_qos_request_active(req)) {
327 WARN(1, KERN_ERR "%s called for unknown object\n", __func__);
328 return;
329 }
330
331 trace_pm_qos_remove_request(PM_QOS_DEFAULT_VALUE);
332
333 cpu_latency_qos_apply(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
334 memset(req, 0, sizeof(*req));
335}
336EXPORT_SYMBOL_GPL(cpu_latency_qos_remove_request);
337
338/* User space interface to the CPU latency QoS via misc device. */
339
340static int cpu_latency_qos_open(struct inode *inode, struct file *filp)
341{
342 struct pm_qos_request *req;
343
344 req = kzalloc_obj(*req);
345 if (!req)
346 return -ENOMEM;
347
348 cpu_latency_qos_add_request(req, PM_QOS_DEFAULT_VALUE);
349 filp->private_data = req;
350
351 return 0;
352}
353
354static int cpu_latency_qos_release(struct inode *inode, struct file *filp)
355{
356 struct pm_qos_request *req = filp->private_data;
357
358 filp->private_data = NULL;
359
360 cpu_latency_qos_remove_request(req);
361 kfree(req);
362
363 return 0;
364}
365
366static ssize_t cpu_latency_qos_read(struct file *filp, char __user *buf,
367 size_t count, loff_t *f_pos)
368{
369 struct pm_qos_request *req = filp->private_data;
370 unsigned long flags;
371 s32 value;
372
373 if (!req || !cpu_latency_qos_request_active(req))
374 return -EINVAL;
375
376 spin_lock_irqsave(&pm_qos_lock, flags);
377 value = pm_qos_get_value(&cpu_latency_constraints);
378 spin_unlock_irqrestore(&pm_qos_lock, flags);
379
380 return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
381}
382
383static ssize_t cpu_latency_qos_write(struct file *filp, const char __user *buf,
384 size_t count, loff_t *f_pos)
385{
386 s32 value;
387
388 if (count == sizeof(s32)) {
389 if (copy_from_user(&value, buf, sizeof(s32)))
390 return -EFAULT;
391 } else {
392 int ret;
393
394 ret = kstrtos32_from_user(buf, count, 16, &value);
395 if (ret)
396 return ret;
397 }
398
399 cpu_latency_qos_update_request(filp->private_data, value);
400
401 return count;
402}
403
404static const struct file_operations cpu_latency_qos_fops = {
405 .write = cpu_latency_qos_write,
406 .read = cpu_latency_qos_read,
407 .open = cpu_latency_qos_open,
408 .release = cpu_latency_qos_release,
409 .llseek = noop_llseek,
410};
411
412static struct miscdevice cpu_latency_qos_miscdev = {
413 .minor = MISC_DYNAMIC_MINOR,
414 .name = "cpu_dma_latency",
415 .fops = &cpu_latency_qos_fops,
416};
417
418#ifdef CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP
419/* The CPU system wakeup latency QoS. */
420static struct pm_qos_constraints cpu_wakeup_latency_constraints = {
421 .list = PLIST_HEAD_INIT(cpu_wakeup_latency_constraints.list),
422 .target_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT,
423 .default_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT,
424 .no_constraint_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT,
425 .type = PM_QOS_MIN,
426};
427
428/**
429 * cpu_wakeup_latency_qos_limit - Current CPU system wakeup latency QoS limit.
430 *
431 * Returns the current CPU system wakeup latency QoS limit that may have been
432 * requested by user space.
433 */
434s32 cpu_wakeup_latency_qos_limit(void)
435{
436 return pm_qos_read_value(&cpu_wakeup_latency_constraints);
437}
438
439static int cpu_wakeup_latency_qos_open(struct inode *inode, struct file *filp)
440{
441 struct pm_qos_request *req;
442
443 req = kzalloc_obj(*req);
444 if (!req)
445 return -ENOMEM;
446
447 req->qos = &cpu_wakeup_latency_constraints;
448 pm_qos_update_target(req->qos, &req->node, PM_QOS_ADD_REQ,
449 PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
450 filp->private_data = req;
451
452 return 0;
453}
454
455static int cpu_wakeup_latency_qos_release(struct inode *inode,
456 struct file *filp)
457{
458 struct pm_qos_request *req = filp->private_data;
459
460 filp->private_data = NULL;
461 pm_qos_update_target(req->qos, &req->node, PM_QOS_REMOVE_REQ,
462 PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
463 kfree(req);
464
465 return 0;
466}
467
468static ssize_t cpu_wakeup_latency_qos_read(struct file *filp, char __user *buf,
469 size_t count, loff_t *f_pos)
470{
471 s32 value = pm_qos_read_value(&cpu_wakeup_latency_constraints);
472
473 return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
474}
475
476static ssize_t cpu_wakeup_latency_qos_write(struct file *filp,
477 const char __user *buf,
478 size_t count, loff_t *f_pos)
479{
480 struct pm_qos_request *req = filp->private_data;
481 s32 value;
482
483 if (count == sizeof(s32)) {
484 if (copy_from_user(&value, buf, sizeof(s32)))
485 return -EFAULT;
486 } else {
487 int ret;
488
489 ret = kstrtos32_from_user(buf, count, 16, &value);
490 if (ret)
491 return ret;
492 }
493
494 if (value < 0)
495 return -EINVAL;
496
497 pm_qos_update_target(req->qos, &req->node, PM_QOS_UPDATE_REQ, value);
498
499 return count;
500}
501
502static const struct file_operations cpu_wakeup_latency_qos_fops = {
503 .open = cpu_wakeup_latency_qos_open,
504 .release = cpu_wakeup_latency_qos_release,
505 .read = cpu_wakeup_latency_qos_read,
506 .write = cpu_wakeup_latency_qos_write,
507 .llseek = noop_llseek,
508};
509
510static struct miscdevice cpu_wakeup_latency_qos_miscdev = {
511 .minor = MISC_DYNAMIC_MINOR,
512 .name = "cpu_wakeup_latency",
513 .fops = &cpu_wakeup_latency_qos_fops,
514};
515#endif /* CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP */
516
517static int __init cpu_latency_qos_init(void)
518{
519 int ret;
520
521 ret = misc_register(&cpu_latency_qos_miscdev);
522 if (ret < 0) {
523 pr_err("%s: %s setup failed\n", __func__,
524 cpu_latency_qos_miscdev.name);
525 return ret;
526 }
527
528#ifdef CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP
529 ret = misc_register(&cpu_wakeup_latency_qos_miscdev);
530 if (ret < 0) {
531 pr_err("%s: %s setup failed\n", __func__,
532 cpu_wakeup_latency_qos_miscdev.name);
533 misc_deregister(&cpu_latency_qos_miscdev);
534 return ret;
535 }
536#endif
537
538 return 0;
539}
540late_initcall(cpu_latency_qos_init);
541#endif /* CONFIG_CPU_IDLE */
542
543/* Definitions related to the frequency QoS below. */
544
545static inline bool freq_qos_value_invalid(s32 value)
546{
547 return value < 0 && value != PM_QOS_DEFAULT_VALUE;
548}
549
550/**
551 * freq_constraints_init - Initialize frequency QoS constraints.
552 * @qos: Frequency QoS constraints to initialize.
553 */
554void freq_constraints_init(struct freq_constraints *qos)
555{
556 struct pm_qos_constraints *c;
557
558 c = &qos->min_freq;
559 plist_head_init(&c->list);
560 c->target_value = FREQ_QOS_MIN_DEFAULT_VALUE;
561 c->default_value = FREQ_QOS_MIN_DEFAULT_VALUE;
562 c->no_constraint_value = FREQ_QOS_MIN_DEFAULT_VALUE;
563 c->type = PM_QOS_MAX;
564 c->notifiers = &qos->min_freq_notifiers;
565 BLOCKING_INIT_NOTIFIER_HEAD(c->notifiers);
566
567 c = &qos->max_freq;
568 plist_head_init(&c->list);
569 c->target_value = FREQ_QOS_MAX_DEFAULT_VALUE;
570 c->default_value = FREQ_QOS_MAX_DEFAULT_VALUE;
571 c->no_constraint_value = FREQ_QOS_MAX_DEFAULT_VALUE;
572 c->type = PM_QOS_MIN;
573 c->notifiers = &qos->max_freq_notifiers;
574 BLOCKING_INIT_NOTIFIER_HEAD(c->notifiers);
575}
576
577/**
578 * freq_qos_read_value - Get frequency QoS constraint for a given list.
579 * @qos: Constraints to evaluate.
580 * @type: QoS request type.
581 */
582s32 freq_qos_read_value(struct freq_constraints *qos,
583 enum freq_qos_req_type type)
584{
585 s32 ret;
586
587 switch (type) {
588 case FREQ_QOS_MIN:
589 ret = IS_ERR_OR_NULL(qos) ?
590 FREQ_QOS_MIN_DEFAULT_VALUE :
591 pm_qos_read_value(&qos->min_freq);
592 break;
593 case FREQ_QOS_MAX:
594 ret = IS_ERR_OR_NULL(qos) ?
595 FREQ_QOS_MAX_DEFAULT_VALUE :
596 pm_qos_read_value(&qos->max_freq);
597 break;
598 default:
599 WARN_ON(1);
600 ret = 0;
601 }
602
603 return ret;
604}
605
606/**
607 * freq_qos_apply - Add/modify/remove frequency QoS request.
608 * @req: Constraint request to apply.
609 * @action: Action to perform (add/update/remove).
610 * @value: Value to assign to the QoS request.
611 *
612 * This is only meant to be called from inside pm_qos, not drivers.
613 */
614int freq_qos_apply(struct freq_qos_request *req,
615 enum pm_qos_req_action action, s32 value)
616{
617 int ret;
618
619 switch(req->type) {
620 case FREQ_QOS_MIN:
621 ret = pm_qos_update_target(&req->qos->min_freq, &req->pnode,
622 action, value);
623 break;
624 case FREQ_QOS_MAX:
625 ret = pm_qos_update_target(&req->qos->max_freq, &req->pnode,
626 action, value);
627 break;
628 default:
629 ret = -EINVAL;
630 }
631
632 return ret;
633}
634
635/**
636 * freq_qos_add_request - Insert new frequency QoS request into a given list.
637 * @qos: Constraints to update.
638 * @req: Preallocated request object.
639 * @type: Request type.
640 * @value: Request value.
641 *
642 * Insert a new entry into the @qos list of requests, recompute the effective
643 * QoS constraint value for that list and initialize the @req object. The
644 * caller needs to save that object for later use in updates and removal.
645 *
646 * Return 1 if the effective constraint value has changed, 0 if the effective
647 * constraint value has not changed, or a negative error code on failures.
648 */
649int freq_qos_add_request(struct freq_constraints *qos,
650 struct freq_qos_request *req,
651 enum freq_qos_req_type type, s32 value)
652{
653 int ret;
654
655 if (IS_ERR_OR_NULL(qos) || !req || freq_qos_value_invalid(value))
656 return -EINVAL;
657
658 if (WARN(freq_qos_request_active(req),
659 "%s() called for active request\n", __func__))
660 return -EINVAL;
661
662 req->qos = qos;
663 req->type = type;
664 ret = freq_qos_apply(req, PM_QOS_ADD_REQ, value);
665 if (ret < 0) {
666 req->qos = NULL;
667 req->type = 0;
668 }
669
670 return ret;
671}
672EXPORT_SYMBOL_GPL(freq_qos_add_request);
673
674/**
675 * freq_qos_update_request - Modify existing frequency QoS request.
676 * @req: Request to modify.
677 * @new_value: New request value.
678 *
679 * Update an existing frequency QoS request along with the effective constraint
680 * value for the list of requests it belongs to.
681 *
682 * Return 1 if the effective constraint value has changed, 0 if the effective
683 * constraint value has not changed, or a negative error code on failures.
684 */
685int freq_qos_update_request(struct freq_qos_request *req, s32 new_value)
686{
687 if (!req || freq_qos_value_invalid(new_value))
688 return -EINVAL;
689
690 if (WARN(!freq_qos_request_active(req),
691 "%s() called for unknown object\n", __func__))
692 return -EINVAL;
693
694 if (req->pnode.prio == new_value)
695 return 0;
696
697 return freq_qos_apply(req, PM_QOS_UPDATE_REQ, new_value);
698}
699EXPORT_SYMBOL_GPL(freq_qos_update_request);
700
701/**
702 * freq_qos_remove_request - Remove frequency QoS request from its list.
703 * @req: Request to remove.
704 *
705 * Remove the given frequency QoS request from the list of constraints it
706 * belongs to and recompute the effective constraint value for that list.
707 *
708 * Return 1 if the effective constraint value has changed, 0 if the effective
709 * constraint value has not changed, or a negative error code on failures.
710 */
711int freq_qos_remove_request(struct freq_qos_request *req)
712{
713 int ret;
714
715 if (!req)
716 return -EINVAL;
717
718 if (WARN(!freq_qos_request_active(req),
719 "%s() called for unknown object\n", __func__))
720 return -EINVAL;
721
722 ret = freq_qos_apply(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
723 req->qos = NULL;
724 req->type = 0;
725
726 return ret;
727}
728EXPORT_SYMBOL_GPL(freq_qos_remove_request);
729
730/**
731 * freq_qos_add_notifier - Add frequency QoS change notifier.
732 * @qos: List of requests to add the notifier to.
733 * @type: Request type.
734 * @notifier: Notifier block to add.
735 */
736int freq_qos_add_notifier(struct freq_constraints *qos,
737 enum freq_qos_req_type type,
738 struct notifier_block *notifier)
739{
740 int ret;
741
742 if (IS_ERR_OR_NULL(qos) || !notifier)
743 return -EINVAL;
744
745 switch (type) {
746 case FREQ_QOS_MIN:
747 ret = blocking_notifier_chain_register(qos->min_freq.notifiers,
748 notifier);
749 break;
750 case FREQ_QOS_MAX:
751 ret = blocking_notifier_chain_register(qos->max_freq.notifiers,
752 notifier);
753 break;
754 default:
755 WARN_ON(1);
756 ret = -EINVAL;
757 }
758
759 return ret;
760}
761EXPORT_SYMBOL_GPL(freq_qos_add_notifier);
762
763/**
764 * freq_qos_remove_notifier - Remove frequency QoS change notifier.
765 * @qos: List of requests to remove the notifier from.
766 * @type: Request type.
767 * @notifier: Notifier block to remove.
768 */
769int freq_qos_remove_notifier(struct freq_constraints *qos,
770 enum freq_qos_req_type type,
771 struct notifier_block *notifier)
772{
773 int ret;
774
775 if (IS_ERR_OR_NULL(qos) || !notifier)
776 return -EINVAL;
777
778 switch (type) {
779 case FREQ_QOS_MIN:
780 ret = blocking_notifier_chain_unregister(qos->min_freq.notifiers,
781 notifier);
782 break;
783 case FREQ_QOS_MAX:
784 ret = blocking_notifier_chain_unregister(qos->max_freq.notifiers,
785 notifier);
786 break;
787 default:
788 WARN_ON(1);
789 ret = -EINVAL;
790 }
791
792 return ret;
793}
794EXPORT_SYMBOL_GPL(freq_qos_remove_notifier);