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 <mgross@linux.intel.com>
9 * Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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(head: &c->list))
61 return c->no_constraint_value;
62
63 switch (c->type) {
64 case PM_QOS_MIN:
65 return plist_first(head: &c->list)->prio;
66
67 case PM_QOS_MAX:
68 return plist_last(head: &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, head: &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, head: &c->list);
122 fallthrough;
123 case PM_QOS_ADD_REQ:
124 plist_node_init(node, prio: new_value);
125 plist_add(node, head: &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, value: curr_value);
134
135 spin_unlock_irqrestore(lock: &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(nh: c->notifiers, val: 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(entry: &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(head: &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(list: &req->node);
195 list_add_tail(new: &req->node, head: &pqf->list);
196 pqf->effective_flags |= val;
197 break;
198 default:
199 /* no action */
200 ;
201 }
202
203 curr_value = list_empty(head: &pqf->list) ? 0 : pqf->effective_flags;
204
205 spin_unlock_irqrestore(lock: &pm_qos_lock, flags: 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(c: &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(c: req->qos, node: &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, action: 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(value: 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(value: new_value);
306
307 if (new_value == req->node.prio)
308 return;
309
310 cpu_latency_qos_apply(req, action: PM_QOS_UPDATE_REQ, value: 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, action: PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
334 memset(s: req, c: 0, n: 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(sizeof(*req), GFP_KERNEL);
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(objp: 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(c: &cpu_latency_constraints);
378 spin_unlock_irqrestore(lock: &pm_qos_lock, flags);
379
380 return simple_read_from_buffer(to: buf, count, ppos: f_pos, from: &value, available: 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(to: &value, from: buf, n: sizeof(s32)))
390 return -EFAULT;
391 } else {
392 int ret;
393
394 ret = kstrtos32_from_user(s: buf, count, base: 16, res: &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
418static int __init cpu_latency_qos_init(void)
419{
420 int ret;
421
422 ret = misc_register(misc: &cpu_latency_qos_miscdev);
423 if (ret < 0)
424 pr_err("%s: %s setup failed\n", __func__,
425 cpu_latency_qos_miscdev.name);
426
427 return ret;
428}
429late_initcall(cpu_latency_qos_init);
430#endif /* CONFIG_CPU_IDLE */
431
432/* Definitions related to the frequency QoS below. */
433
434static inline bool freq_qos_value_invalid(s32 value)
435{
436 return value < 0 && value != PM_QOS_DEFAULT_VALUE;
437}
438
439/**
440 * freq_constraints_init - Initialize frequency QoS constraints.
441 * @qos: Frequency QoS constraints to initialize.
442 */
443void freq_constraints_init(struct freq_constraints *qos)
444{
445 struct pm_qos_constraints *c;
446
447 c = &qos->min_freq;
448 plist_head_init(head: &c->list);
449 c->target_value = FREQ_QOS_MIN_DEFAULT_VALUE;
450 c->default_value = FREQ_QOS_MIN_DEFAULT_VALUE;
451 c->no_constraint_value = FREQ_QOS_MIN_DEFAULT_VALUE;
452 c->type = PM_QOS_MAX;
453 c->notifiers = &qos->min_freq_notifiers;
454 BLOCKING_INIT_NOTIFIER_HEAD(c->notifiers);
455
456 c = &qos->max_freq;
457 plist_head_init(head: &c->list);
458 c->target_value = FREQ_QOS_MAX_DEFAULT_VALUE;
459 c->default_value = FREQ_QOS_MAX_DEFAULT_VALUE;
460 c->no_constraint_value = FREQ_QOS_MAX_DEFAULT_VALUE;
461 c->type = PM_QOS_MIN;
462 c->notifiers = &qos->max_freq_notifiers;
463 BLOCKING_INIT_NOTIFIER_HEAD(c->notifiers);
464}
465
466/**
467 * freq_qos_read_value - Get frequency QoS constraint for a given list.
468 * @qos: Constraints to evaluate.
469 * @type: QoS request type.
470 */
471s32 freq_qos_read_value(struct freq_constraints *qos,
472 enum freq_qos_req_type type)
473{
474 s32 ret;
475
476 switch (type) {
477 case FREQ_QOS_MIN:
478 ret = IS_ERR_OR_NULL(ptr: qos) ?
479 FREQ_QOS_MIN_DEFAULT_VALUE :
480 pm_qos_read_value(c: &qos->min_freq);
481 break;
482 case FREQ_QOS_MAX:
483 ret = IS_ERR_OR_NULL(ptr: qos) ?
484 FREQ_QOS_MAX_DEFAULT_VALUE :
485 pm_qos_read_value(c: &qos->max_freq);
486 break;
487 default:
488 WARN_ON(1);
489 ret = 0;
490 }
491
492 return ret;
493}
494
495/**
496 * freq_qos_apply - Add/modify/remove frequency QoS request.
497 * @req: Constraint request to apply.
498 * @action: Action to perform (add/update/remove).
499 * @value: Value to assign to the QoS request.
500 *
501 * This is only meant to be called from inside pm_qos, not drivers.
502 */
503int freq_qos_apply(struct freq_qos_request *req,
504 enum pm_qos_req_action action, s32 value)
505{
506 int ret;
507
508 switch(req->type) {
509 case FREQ_QOS_MIN:
510 ret = pm_qos_update_target(c: &req->qos->min_freq, node: &req->pnode,
511 action, value);
512 break;
513 case FREQ_QOS_MAX:
514 ret = pm_qos_update_target(c: &req->qos->max_freq, node: &req->pnode,
515 action, value);
516 break;
517 default:
518 ret = -EINVAL;
519 }
520
521 return ret;
522}
523
524/**
525 * freq_qos_add_request - Insert new frequency QoS request into a given list.
526 * @qos: Constraints to update.
527 * @req: Preallocated request object.
528 * @type: Request type.
529 * @value: Request value.
530 *
531 * Insert a new entry into the @qos list of requests, recompute the effective
532 * QoS constraint value for that list and initialize the @req object. The
533 * caller needs to save that object for later use in updates and removal.
534 *
535 * Return 1 if the effective constraint value has changed, 0 if the effective
536 * constraint value has not changed, or a negative error code on failures.
537 */
538int freq_qos_add_request(struct freq_constraints *qos,
539 struct freq_qos_request *req,
540 enum freq_qos_req_type type, s32 value)
541{
542 int ret;
543
544 if (IS_ERR_OR_NULL(ptr: qos) || !req || freq_qos_value_invalid(value))
545 return -EINVAL;
546
547 if (WARN(freq_qos_request_active(req),
548 "%s() called for active request\n", __func__))
549 return -EINVAL;
550
551 req->qos = qos;
552 req->type = type;
553 ret = freq_qos_apply(req, action: PM_QOS_ADD_REQ, value);
554 if (ret < 0) {
555 req->qos = NULL;
556 req->type = 0;
557 }
558
559 return ret;
560}
561EXPORT_SYMBOL_GPL(freq_qos_add_request);
562
563/**
564 * freq_qos_update_request - Modify existing frequency QoS request.
565 * @req: Request to modify.
566 * @new_value: New request value.
567 *
568 * Update an existing frequency QoS request along with the effective constraint
569 * value for the list of requests it belongs to.
570 *
571 * Return 1 if the effective constraint value has changed, 0 if the effective
572 * constraint value has not changed, or a negative error code on failures.
573 */
574int freq_qos_update_request(struct freq_qos_request *req, s32 new_value)
575{
576 if (!req || freq_qos_value_invalid(value: new_value))
577 return -EINVAL;
578
579 if (WARN(!freq_qos_request_active(req),
580 "%s() called for unknown object\n", __func__))
581 return -EINVAL;
582
583 if (req->pnode.prio == new_value)
584 return 0;
585
586 return freq_qos_apply(req, action: PM_QOS_UPDATE_REQ, value: new_value);
587}
588EXPORT_SYMBOL_GPL(freq_qos_update_request);
589
590/**
591 * freq_qos_remove_request - Remove frequency QoS request from its list.
592 * @req: Request to remove.
593 *
594 * Remove the given frequency QoS request from the list of constraints it
595 * belongs to and recompute the effective constraint value for that list.
596 *
597 * Return 1 if the effective constraint value has changed, 0 if the effective
598 * constraint value has not changed, or a negative error code on failures.
599 */
600int freq_qos_remove_request(struct freq_qos_request *req)
601{
602 int ret;
603
604 if (!req)
605 return -EINVAL;
606
607 if (WARN(!freq_qos_request_active(req),
608 "%s() called for unknown object\n", __func__))
609 return -EINVAL;
610
611 ret = freq_qos_apply(req, action: PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
612 req->qos = NULL;
613 req->type = 0;
614
615 return ret;
616}
617EXPORT_SYMBOL_GPL(freq_qos_remove_request);
618
619/**
620 * freq_qos_add_notifier - Add frequency QoS change notifier.
621 * @qos: List of requests to add the notifier to.
622 * @type: Request type.
623 * @notifier: Notifier block to add.
624 */
625int freq_qos_add_notifier(struct freq_constraints *qos,
626 enum freq_qos_req_type type,
627 struct notifier_block *notifier)
628{
629 int ret;
630
631 if (IS_ERR_OR_NULL(ptr: qos) || !notifier)
632 return -EINVAL;
633
634 switch (type) {
635 case FREQ_QOS_MIN:
636 ret = blocking_notifier_chain_register(nh: qos->min_freq.notifiers,
637 nb: notifier);
638 break;
639 case FREQ_QOS_MAX:
640 ret = blocking_notifier_chain_register(nh: qos->max_freq.notifiers,
641 nb: notifier);
642 break;
643 default:
644 WARN_ON(1);
645 ret = -EINVAL;
646 }
647
648 return ret;
649}
650EXPORT_SYMBOL_GPL(freq_qos_add_notifier);
651
652/**
653 * freq_qos_remove_notifier - Remove frequency QoS change notifier.
654 * @qos: List of requests to remove the notifier from.
655 * @type: Request type.
656 * @notifier: Notifier block to remove.
657 */
658int freq_qos_remove_notifier(struct freq_constraints *qos,
659 enum freq_qos_req_type type,
660 struct notifier_block *notifier)
661{
662 int ret;
663
664 if (IS_ERR_OR_NULL(ptr: qos) || !notifier)
665 return -EINVAL;
666
667 switch (type) {
668 case FREQ_QOS_MIN:
669 ret = blocking_notifier_chain_unregister(nh: qos->min_freq.notifiers,
670 nb: notifier);
671 break;
672 case FREQ_QOS_MAX:
673 ret = blocking_notifier_chain_unregister(nh: qos->max_freq.notifiers,
674 nb: notifier);
675 break;
676 default:
677 WARN_ON(1);
678 ret = -EINVAL;
679 }
680
681 return ret;
682}
683EXPORT_SYMBOL_GPL(freq_qos_remove_notifier);
684