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1/*
2 * This module exposes the interface to kernel space for specifying
3 * QoS dependencies. It provides infrastructure for registration of:
4 *
5 * Dependents on a QoS value : register requests
6 * Watchers of QoS value : get notified when target QoS value changes
7 *
8 * This QoS design is best effort based. Dependents register their QoS needs.
9 * Watchers register to keep track of the current QoS needs of the system.
10 *
11 * There are 3 basic classes of QoS parameter: latency, timeout, throughput
12 * each have defined units:
13 * latency: usec
14 * timeout: usec <-- currently not used.
15 * throughput: kbs (kilo byte / sec)
16 *
17 * There are lists of pm_qos_objects each one wrapping requests, notifiers
18 *
19 * User mode requests on a QOS parameter register themselves to the
20 * subsystem by opening the device node /dev/... and writing there request to
21 * the node. As long as the process holds a file handle open to the node the
22 * client continues to be accounted for. Upon file release the usermode
23 * request is removed and a new qos target is computed. This way when the
24 * request that the application has is cleaned up when closes the file
25 * pointer or exits the pm_qos_object will get an opportunity to clean up.
26 *
27 * Mark Gross <mgross@linux.intel.com>
28 */
29
30/*#define DEBUG*/
31
32#include <linux/pm_qos.h>
33#include <linux/sched.h>
34#include <linux/spinlock.h>
35#include <linux/slab.h>
36#include <linux/time.h>
37#include <linux/fs.h>
38#include <linux/device.h>
39#include <linux/miscdevice.h>
40#include <linux/string.h>
41#include <linux/platform_device.h>
42#include <linux/init.h>
43#include <linux/kernel.h>
44#include <linux/debugfs.h>
45#include <linux/seq_file.h>
46
47#include <linux/uaccess.h>
48#include <linux/export.h>
49#include <trace/events/power.h>
50
51/*
52 * locking rule: all changes to constraints or notifiers lists
53 * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
54 * held, taken with _irqsave. One lock to rule them all
55 */
56struct pm_qos_object {
57 struct pm_qos_constraints *constraints;
58 struct miscdevice pm_qos_power_miscdev;
59 char *name;
60};
61
62static DEFINE_SPINLOCK(pm_qos_lock);
63
64static struct pm_qos_object null_pm_qos;
65
66static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
67static struct pm_qos_constraints cpu_dma_constraints = {
68 .list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
69 .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
70 .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
71 .no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
72 .type = PM_QOS_MIN,
73 .notifiers = &cpu_dma_lat_notifier,
74};
75static struct pm_qos_object cpu_dma_pm_qos = {
76 .constraints = &cpu_dma_constraints,
77 .name = "cpu_dma_latency",
78};
79
80static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
81static struct pm_qos_constraints network_lat_constraints = {
82 .list = PLIST_HEAD_INIT(network_lat_constraints.list),
83 .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
84 .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
85 .no_constraint_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
86 .type = PM_QOS_MIN,
87 .notifiers = &network_lat_notifier,
88};
89static struct pm_qos_object network_lat_pm_qos = {
90 .constraints = &network_lat_constraints,
91 .name = "network_latency",
92};
93
94
95static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
96static struct pm_qos_constraints network_tput_constraints = {
97 .list = PLIST_HEAD_INIT(network_tput_constraints.list),
98 .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
99 .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
100 .no_constraint_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
101 .type = PM_QOS_MAX,
102 .notifiers = &network_throughput_notifier,
103};
104static struct pm_qos_object network_throughput_pm_qos = {
105 .constraints = &network_tput_constraints,
106 .name = "network_throughput",
107};
108
109
110static BLOCKING_NOTIFIER_HEAD(memory_bandwidth_notifier);
111static struct pm_qos_constraints memory_bw_constraints = {
112 .list = PLIST_HEAD_INIT(memory_bw_constraints.list),
113 .target_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
114 .default_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
115 .no_constraint_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
116 .type = PM_QOS_SUM,
117 .notifiers = &memory_bandwidth_notifier,
118};
119static struct pm_qos_object memory_bandwidth_pm_qos = {
120 .constraints = &memory_bw_constraints,
121 .name = "memory_bandwidth",
122};
123
124
125static struct pm_qos_object *pm_qos_array[] = {
126 &null_pm_qos,
127 &cpu_dma_pm_qos,
128 &network_lat_pm_qos,
129 &network_throughput_pm_qos,
130 &memory_bandwidth_pm_qos,
131};
132
133static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
134 size_t count, loff_t *f_pos);
135static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
136 size_t count, loff_t *f_pos);
137static int pm_qos_power_open(struct inode *inode, struct file *filp);
138static int pm_qos_power_release(struct inode *inode, struct file *filp);
139
140static const struct file_operations pm_qos_power_fops = {
141 .write = pm_qos_power_write,
142 .read = pm_qos_power_read,
143 .open = pm_qos_power_open,
144 .release = pm_qos_power_release,
145 .llseek = noop_llseek,
146};
147
148/* unlocked internal variant */
149static inline int pm_qos_get_value(struct pm_qos_constraints *c)
150{
151 struct plist_node *node;
152 int total_value = 0;
153
154 if (plist_head_empty(&c->list))
155 return c->no_constraint_value;
156
157 switch (c->type) {
158 case PM_QOS_MIN:
159 return plist_first(&c->list)->prio;
160
161 case PM_QOS_MAX:
162 return plist_last(&c->list)->prio;
163
164 case PM_QOS_SUM:
165 plist_for_each(node, &c->list)
166 total_value += node->prio;
167
168 return total_value;
169
170 default:
171 /* runtime check for not using enum */
172 BUG();
173 return PM_QOS_DEFAULT_VALUE;
174 }
175}
176
177s32 pm_qos_read_value(struct pm_qos_constraints *c)
178{
179 return c->target_value;
180}
181
182static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
183{
184 c->target_value = value;
185}
186
187static inline int pm_qos_get_value(struct pm_qos_constraints *c);
188static int pm_qos_dbg_show_requests(struct seq_file *s, void *unused)
189{
190 struct pm_qos_object *qos = (struct pm_qos_object *)s->private;
191 struct pm_qos_constraints *c;
192 struct pm_qos_request *req;
193 char *type;
194 unsigned long flags;
195 int tot_reqs = 0;
196 int active_reqs = 0;
197
198 if (IS_ERR_OR_NULL(qos)) {
199 pr_err("%s: bad qos param!\n", __func__);
200 return -EINVAL;
201 }
202 c = qos->constraints;
203 if (IS_ERR_OR_NULL(c)) {
204 pr_err("%s: Bad constraints on qos?\n", __func__);
205 return -EINVAL;
206 }
207
208 /* Lock to ensure we have a snapshot */
209 spin_lock_irqsave(&pm_qos_lock, flags);
210 if (plist_head_empty(&c->list)) {
211 seq_puts(s, "Empty!\n");
212 goto out;
213 }
214
215 switch (c->type) {
216 case PM_QOS_MIN:
217 type = "Minimum";
218 break;
219 case PM_QOS_MAX:
220 type = "Maximum";
221 break;
222 case PM_QOS_SUM:
223 type = "Sum";
224 break;
225 default:
226 type = "Unknown";
227 }
228
229 plist_for_each_entry(req, &c->list, node) {
230 char *state = "Default";
231
232 if ((req->node).prio != c->default_value) {
233 active_reqs++;
234 state = "Active";
235 }
236 tot_reqs++;
237 seq_printf(s, "%d: %d: %s\n", tot_reqs,
238 (req->node).prio, state);
239 }
240
241 seq_printf(s, "Type=%s, Value=%d, Requests: active=%d / total=%d\n",
242 type, pm_qos_get_value(c), active_reqs, tot_reqs);
243
244out:
245 spin_unlock_irqrestore(&pm_qos_lock, flags);
246 return 0;
247}
248
249static int pm_qos_dbg_open(struct inode *inode, struct file *file)
250{
251 return single_open(file, pm_qos_dbg_show_requests,
252 inode->i_private);
253}
254
255static const struct file_operations pm_qos_debug_fops = {
256 .open = pm_qos_dbg_open,
257 .read = seq_read,
258 .llseek = seq_lseek,
259 .release = single_release,
260};
261
262/**
263 * pm_qos_update_target - manages the constraints list and calls the notifiers
264 * if needed
265 * @c: constraints data struct
266 * @node: request to add to the list, to update or to remove
267 * @action: action to take on the constraints list
268 * @value: value of the request to add or update
269 *
270 * This function returns 1 if the aggregated constraint value has changed, 0
271 * otherwise.
272 */
273int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
274 enum pm_qos_req_action action, int value)
275{
276 unsigned long flags;
277 int prev_value, curr_value, new_value;
278 int ret;
279
280 spin_lock_irqsave(&pm_qos_lock, flags);
281 prev_value = pm_qos_get_value(c);
282 if (value == PM_QOS_DEFAULT_VALUE)
283 new_value = c->default_value;
284 else
285 new_value = value;
286
287 switch (action) {
288 case PM_QOS_REMOVE_REQ:
289 plist_del(node, &c->list);
290 break;
291 case PM_QOS_UPDATE_REQ:
292 /*
293 * to change the list, we atomically remove, reinit
294 * with new value and add, then see if the extremal
295 * changed
296 */
297 plist_del(node, &c->list);
298 case PM_QOS_ADD_REQ:
299 plist_node_init(node, new_value);
300 plist_add(node, &c->list);
301 break;
302 default:
303 /* no action */
304 ;
305 }
306
307 curr_value = pm_qos_get_value(c);
308 pm_qos_set_value(c, curr_value);
309
310 spin_unlock_irqrestore(&pm_qos_lock, flags);
311
312 trace_pm_qos_update_target(action, prev_value, curr_value);
313 if (prev_value != curr_value) {
314 ret = 1;
315 if (c->notifiers)
316 blocking_notifier_call_chain(c->notifiers,
317 (unsigned long)curr_value,
318 NULL);
319 } else {
320 ret = 0;
321 }
322 return ret;
323}
324
325/**
326 * pm_qos_flags_remove_req - Remove device PM QoS flags request.
327 * @pqf: Device PM QoS flags set to remove the request from.
328 * @req: Request to remove from the set.
329 */
330static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
331 struct pm_qos_flags_request *req)
332{
333 s32 val = 0;
334
335 list_del(&req->node);
336 list_for_each_entry(req, &pqf->list, node)
337 val |= req->flags;
338
339 pqf->effective_flags = val;
340}
341
342/**
343 * pm_qos_update_flags - Update a set of PM QoS flags.
344 * @pqf: Set of flags to update.
345 * @req: Request to add to the set, to modify, or to remove from the set.
346 * @action: Action to take on the set.
347 * @val: Value of the request to add or modify.
348 *
349 * Update the given set of PM QoS flags and call notifiers if the aggregate
350 * value has changed. Returns 1 if the aggregate constraint value has changed,
351 * 0 otherwise.
352 */
353bool pm_qos_update_flags(struct pm_qos_flags *pqf,
354 struct pm_qos_flags_request *req,
355 enum pm_qos_req_action action, s32 val)
356{
357 unsigned long irqflags;
358 s32 prev_value, curr_value;
359
360 spin_lock_irqsave(&pm_qos_lock, irqflags);
361
362 prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
363
364 switch (action) {
365 case PM_QOS_REMOVE_REQ:
366 pm_qos_flags_remove_req(pqf, req);
367 break;
368 case PM_QOS_UPDATE_REQ:
369 pm_qos_flags_remove_req(pqf, req);
370 case PM_QOS_ADD_REQ:
371 req->flags = val;
372 INIT_LIST_HEAD(&req->node);
373 list_add_tail(&req->node, &pqf->list);
374 pqf->effective_flags |= val;
375 break;
376 default:
377 /* no action */
378 ;
379 }
380
381 curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
382
383 spin_unlock_irqrestore(&pm_qos_lock, irqflags);
384
385 trace_pm_qos_update_flags(action, prev_value, curr_value);
386 return prev_value != curr_value;
387}
388
389/**
390 * pm_qos_request - returns current system wide qos expectation
391 * @pm_qos_class: identification of which qos value is requested
392 *
393 * This function returns the current target value.
394 */
395int pm_qos_request(int pm_qos_class)
396{
397 return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
398}
399EXPORT_SYMBOL_GPL(pm_qos_request);
400
401int pm_qos_request_active(struct pm_qos_request *req)
402{
403 return req->pm_qos_class != 0;
404}
405EXPORT_SYMBOL_GPL(pm_qos_request_active);
406
407static void __pm_qos_update_request(struct pm_qos_request *req,
408 s32 new_value)
409{
410 trace_pm_qos_update_request(req->pm_qos_class, new_value);
411
412 if (new_value != req->node.prio)
413 pm_qos_update_target(
414 pm_qos_array[req->pm_qos_class]->constraints,
415 &req->node, PM_QOS_UPDATE_REQ, new_value);
416}
417
418/**
419 * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
420 * @work: work struct for the delayed work (timeout)
421 *
422 * This cancels the timeout request by falling back to the default at timeout.
423 */
424static void pm_qos_work_fn(struct work_struct *work)
425{
426 struct pm_qos_request *req = container_of(to_delayed_work(work),
427 struct pm_qos_request,
428 work);
429
430 __pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
431}
432
433/**
434 * pm_qos_add_request - inserts new qos request into the list
435 * @req: pointer to a preallocated handle
436 * @pm_qos_class: identifies which list of qos request to use
437 * @value: defines the qos request
438 *
439 * This function inserts a new entry in the pm_qos_class list of requested qos
440 * performance characteristics. It recomputes the aggregate QoS expectations
441 * for the pm_qos_class of parameters and initializes the pm_qos_request
442 * handle. Caller needs to save this handle for later use in updates and
443 * removal.
444 */
445
446void pm_qos_add_request(struct pm_qos_request *req,
447 int pm_qos_class, s32 value)
448{
449 if (!req) /*guard against callers passing in null */
450 return;
451
452 if (pm_qos_request_active(req)) {
453 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
454 return;
455 }
456 req->pm_qos_class = pm_qos_class;
457 INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
458 trace_pm_qos_add_request(pm_qos_class, value);
459 pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
460 &req->node, PM_QOS_ADD_REQ, value);
461}
462EXPORT_SYMBOL_GPL(pm_qos_add_request);
463
464/**
465 * pm_qos_update_request - modifies an existing qos request
466 * @req : handle to list element holding a pm_qos request to use
467 * @value: defines the qos request
468 *
469 * Updates an existing qos request for the pm_qos_class of parameters along
470 * with updating the target pm_qos_class value.
471 *
472 * Attempts are made to make this code callable on hot code paths.
473 */
474void pm_qos_update_request(struct pm_qos_request *req,
475 s32 new_value)
476{
477 if (!req) /*guard against callers passing in null */
478 return;
479
480 if (!pm_qos_request_active(req)) {
481 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
482 return;
483 }
484
485 cancel_delayed_work_sync(&req->work);
486 __pm_qos_update_request(req, new_value);
487}
488EXPORT_SYMBOL_GPL(pm_qos_update_request);
489
490/**
491 * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
492 * @req : handle to list element holding a pm_qos request to use
493 * @new_value: defines the temporal qos request
494 * @timeout_us: the effective duration of this qos request in usecs.
495 *
496 * After timeout_us, this qos request is cancelled automatically.
497 */
498void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
499 unsigned long timeout_us)
500{
501 if (!req)
502 return;
503 if (WARN(!pm_qos_request_active(req),
504 "%s called for unknown object.", __func__))
505 return;
506
507 cancel_delayed_work_sync(&req->work);
508
509 trace_pm_qos_update_request_timeout(req->pm_qos_class,
510 new_value, timeout_us);
511 if (new_value != req->node.prio)
512 pm_qos_update_target(
513 pm_qos_array[req->pm_qos_class]->constraints,
514 &req->node, PM_QOS_UPDATE_REQ, new_value);
515
516 schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
517}
518
519/**
520 * pm_qos_remove_request - modifies an existing qos request
521 * @req: handle to request list element
522 *
523 * Will remove pm qos request from the list of constraints and
524 * recompute the current target value for the pm_qos_class. Call this
525 * on slow code paths.
526 */
527void pm_qos_remove_request(struct pm_qos_request *req)
528{
529 if (!req) /*guard against callers passing in null */
530 return;
531 /* silent return to keep pcm code cleaner */
532
533 if (!pm_qos_request_active(req)) {
534 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
535 return;
536 }
537
538 cancel_delayed_work_sync(&req->work);
539
540 trace_pm_qos_remove_request(req->pm_qos_class, PM_QOS_DEFAULT_VALUE);
541 pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
542 &req->node, PM_QOS_REMOVE_REQ,
543 PM_QOS_DEFAULT_VALUE);
544 memset(req, 0, sizeof(*req));
545}
546EXPORT_SYMBOL_GPL(pm_qos_remove_request);
547
548/**
549 * pm_qos_add_notifier - sets notification entry for changes to target value
550 * @pm_qos_class: identifies which qos target changes should be notified.
551 * @notifier: notifier block managed by caller.
552 *
553 * will register the notifier into a notification chain that gets called
554 * upon changes to the pm_qos_class target value.
555 */
556int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
557{
558 int retval;
559
560 retval = blocking_notifier_chain_register(
561 pm_qos_array[pm_qos_class]->constraints->notifiers,
562 notifier);
563
564 return retval;
565}
566EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
567
568/**
569 * pm_qos_remove_notifier - deletes notification entry from chain.
570 * @pm_qos_class: identifies which qos target changes are notified.
571 * @notifier: notifier block to be removed.
572 *
573 * will remove the notifier from the notification chain that gets called
574 * upon changes to the pm_qos_class target value.
575 */
576int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
577{
578 int retval;
579
580 retval = blocking_notifier_chain_unregister(
581 pm_qos_array[pm_qos_class]->constraints->notifiers,
582 notifier);
583
584 return retval;
585}
586EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
587
588/* User space interface to PM QoS classes via misc devices */
589static int register_pm_qos_misc(struct pm_qos_object *qos, struct dentry *d)
590{
591 qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
592 qos->pm_qos_power_miscdev.name = qos->name;
593 qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
594
595 if (d) {
596 (void)debugfs_create_file(qos->name, S_IRUGO, d,
597 (void *)qos, &pm_qos_debug_fops);
598 }
599
600 return misc_register(&qos->pm_qos_power_miscdev);
601}
602
603static int find_pm_qos_object_by_minor(int minor)
604{
605 int pm_qos_class;
606
607 for (pm_qos_class = PM_QOS_CPU_DMA_LATENCY;
608 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
609 if (minor ==
610 pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
611 return pm_qos_class;
612 }
613 return -1;
614}
615
616static int pm_qos_power_open(struct inode *inode, struct file *filp)
617{
618 long pm_qos_class;
619
620 pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
621 if (pm_qos_class >= PM_QOS_CPU_DMA_LATENCY) {
622 struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
623 if (!req)
624 return -ENOMEM;
625
626 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
627 filp->private_data = req;
628
629 return 0;
630 }
631 return -EPERM;
632}
633
634static int pm_qos_power_release(struct inode *inode, struct file *filp)
635{
636 struct pm_qos_request *req;
637
638 req = filp->private_data;
639 pm_qos_remove_request(req);
640 kfree(req);
641
642 return 0;
643}
644
645
646static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
647 size_t count, loff_t *f_pos)
648{
649 s32 value;
650 unsigned long flags;
651 struct pm_qos_request *req = filp->private_data;
652
653 if (!req)
654 return -EINVAL;
655 if (!pm_qos_request_active(req))
656 return -EINVAL;
657
658 spin_lock_irqsave(&pm_qos_lock, flags);
659 value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
660 spin_unlock_irqrestore(&pm_qos_lock, flags);
661
662 return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
663}
664
665static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
666 size_t count, loff_t *f_pos)
667{
668 s32 value;
669 struct pm_qos_request *req;
670
671 if (count == sizeof(s32)) {
672 if (copy_from_user(&value, buf, sizeof(s32)))
673 return -EFAULT;
674 } else {
675 int ret;
676
677 ret = kstrtos32_from_user(buf, count, 16, &value);
678 if (ret)
679 return ret;
680 }
681
682 req = filp->private_data;
683 pm_qos_update_request(req, value);
684
685 return count;
686}
687
688
689static int __init pm_qos_power_init(void)
690{
691 int ret = 0;
692 int i;
693 struct dentry *d;
694
695 BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
696
697 d = debugfs_create_dir("pm_qos", NULL);
698 if (IS_ERR_OR_NULL(d))
699 d = NULL;
700
701 for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) {
702 ret = register_pm_qos_misc(pm_qos_array[i], d);
703 if (ret < 0) {
704 printk(KERN_ERR "pm_qos_param: %s setup failed\n",
705 pm_qos_array[i]->name);
706 return ret;
707 }
708 }
709
710 return ret;
711}
712
713late_initcall(pm_qos_power_init);
1/*
2 * This module exposes the interface to kernel space for specifying
3 * QoS dependencies. It provides infrastructure for registration of:
4 *
5 * Dependents on a QoS value : register requests
6 * Watchers of QoS value : get notified when target QoS value changes
7 *
8 * This QoS design is best effort based. Dependents register their QoS needs.
9 * Watchers register to keep track of the current QoS needs of the system.
10 *
11 * There are 3 basic classes of QoS parameter: latency, timeout, throughput
12 * each have defined units:
13 * latency: usec
14 * timeout: usec <-- currently not used.
15 * throughput: kbs (kilo byte / sec)
16 *
17 * There are lists of pm_qos_objects each one wrapping requests, notifiers
18 *
19 * User mode requests on a QOS parameter register themselves to the
20 * subsystem by opening the device node /dev/... and writing there request to
21 * the node. As long as the process holds a file handle open to the node the
22 * client continues to be accounted for. Upon file release the usermode
23 * request is removed and a new qos target is computed. This way when the
24 * request that the application has is cleaned up when closes the file
25 * pointer or exits the pm_qos_object will get an opportunity to clean up.
26 *
27 * Mark Gross <mgross@linux.intel.com>
28 */
29
30/*#define DEBUG*/
31
32#include <linux/pm_qos.h>
33#include <linux/sched.h>
34#include <linux/spinlock.h>
35#include <linux/slab.h>
36#include <linux/time.h>
37#include <linux/fs.h>
38#include <linux/device.h>
39#include <linux/miscdevice.h>
40#include <linux/string.h>
41#include <linux/platform_device.h>
42#include <linux/init.h>
43#include <linux/kernel.h>
44
45#include <linux/uaccess.h>
46#include <linux/export.h>
47#include <trace/events/power.h>
48
49/*
50 * locking rule: all changes to constraints or notifiers lists
51 * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
52 * held, taken with _irqsave. One lock to rule them all
53 */
54struct pm_qos_object {
55 struct pm_qos_constraints *constraints;
56 struct miscdevice pm_qos_power_miscdev;
57 char *name;
58};
59
60static DEFINE_SPINLOCK(pm_qos_lock);
61
62static struct pm_qos_object null_pm_qos;
63
64static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
65static struct pm_qos_constraints cpu_dma_constraints = {
66 .list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
67 .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
68 .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
69 .no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
70 .type = PM_QOS_MIN,
71 .notifiers = &cpu_dma_lat_notifier,
72};
73static struct pm_qos_object cpu_dma_pm_qos = {
74 .constraints = &cpu_dma_constraints,
75 .name = "cpu_dma_latency",
76};
77
78static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
79static struct pm_qos_constraints network_lat_constraints = {
80 .list = PLIST_HEAD_INIT(network_lat_constraints.list),
81 .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
82 .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
83 .no_constraint_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
84 .type = PM_QOS_MIN,
85 .notifiers = &network_lat_notifier,
86};
87static struct pm_qos_object network_lat_pm_qos = {
88 .constraints = &network_lat_constraints,
89 .name = "network_latency",
90};
91
92
93static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
94static struct pm_qos_constraints network_tput_constraints = {
95 .list = PLIST_HEAD_INIT(network_tput_constraints.list),
96 .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
97 .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
98 .no_constraint_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
99 .type = PM_QOS_MAX,
100 .notifiers = &network_throughput_notifier,
101};
102static struct pm_qos_object network_throughput_pm_qos = {
103 .constraints = &network_tput_constraints,
104 .name = "network_throughput",
105};
106
107
108static struct pm_qos_object *pm_qos_array[] = {
109 &null_pm_qos,
110 &cpu_dma_pm_qos,
111 &network_lat_pm_qos,
112 &network_throughput_pm_qos
113};
114
115static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
116 size_t count, loff_t *f_pos);
117static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
118 size_t count, loff_t *f_pos);
119static int pm_qos_power_open(struct inode *inode, struct file *filp);
120static int pm_qos_power_release(struct inode *inode, struct file *filp);
121
122static const struct file_operations pm_qos_power_fops = {
123 .write = pm_qos_power_write,
124 .read = pm_qos_power_read,
125 .open = pm_qos_power_open,
126 .release = pm_qos_power_release,
127 .llseek = noop_llseek,
128};
129
130/* unlocked internal variant */
131static inline int pm_qos_get_value(struct pm_qos_constraints *c)
132{
133 if (plist_head_empty(&c->list))
134 return c->no_constraint_value;
135
136 switch (c->type) {
137 case PM_QOS_MIN:
138 return plist_first(&c->list)->prio;
139
140 case PM_QOS_MAX:
141 return plist_last(&c->list)->prio;
142
143 default:
144 /* runtime check for not using enum */
145 BUG();
146 return PM_QOS_DEFAULT_VALUE;
147 }
148}
149
150s32 pm_qos_read_value(struct pm_qos_constraints *c)
151{
152 return c->target_value;
153}
154
155static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
156{
157 c->target_value = value;
158}
159
160/**
161 * pm_qos_update_target - manages the constraints list and calls the notifiers
162 * if needed
163 * @c: constraints data struct
164 * @node: request to add to the list, to update or to remove
165 * @action: action to take on the constraints list
166 * @value: value of the request to add or update
167 *
168 * This function returns 1 if the aggregated constraint value has changed, 0
169 * otherwise.
170 */
171int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
172 enum pm_qos_req_action action, int value)
173{
174 unsigned long flags;
175 int prev_value, curr_value, new_value;
176 int ret;
177
178 spin_lock_irqsave(&pm_qos_lock, flags);
179 prev_value = pm_qos_get_value(c);
180 if (value == PM_QOS_DEFAULT_VALUE)
181 new_value = c->default_value;
182 else
183 new_value = value;
184
185 switch (action) {
186 case PM_QOS_REMOVE_REQ:
187 plist_del(node, &c->list);
188 break;
189 case PM_QOS_UPDATE_REQ:
190 /*
191 * to change the list, we atomically remove, reinit
192 * with new value and add, then see if the extremal
193 * changed
194 */
195 plist_del(node, &c->list);
196 case PM_QOS_ADD_REQ:
197 plist_node_init(node, new_value);
198 plist_add(node, &c->list);
199 break;
200 default:
201 /* no action */
202 ;
203 }
204
205 curr_value = pm_qos_get_value(c);
206 pm_qos_set_value(c, curr_value);
207
208 spin_unlock_irqrestore(&pm_qos_lock, flags);
209
210 trace_pm_qos_update_target(action, prev_value, curr_value);
211 if (prev_value != curr_value) {
212 ret = 1;
213 if (c->notifiers)
214 blocking_notifier_call_chain(c->notifiers,
215 (unsigned long)curr_value,
216 NULL);
217 } else {
218 ret = 0;
219 }
220 return ret;
221}
222
223/**
224 * pm_qos_flags_remove_req - Remove device PM QoS flags request.
225 * @pqf: Device PM QoS flags set to remove the request from.
226 * @req: Request to remove from the set.
227 */
228static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
229 struct pm_qos_flags_request *req)
230{
231 s32 val = 0;
232
233 list_del(&req->node);
234 list_for_each_entry(req, &pqf->list, node)
235 val |= req->flags;
236
237 pqf->effective_flags = val;
238}
239
240/**
241 * pm_qos_update_flags - Update a set of PM QoS flags.
242 * @pqf: Set of flags to update.
243 * @req: Request to add to the set, to modify, or to remove from the set.
244 * @action: Action to take on the set.
245 * @val: Value of the request to add or modify.
246 *
247 * Update the given set of PM QoS flags and call notifiers if the aggregate
248 * value has changed. Returns 1 if the aggregate constraint value has changed,
249 * 0 otherwise.
250 */
251bool pm_qos_update_flags(struct pm_qos_flags *pqf,
252 struct pm_qos_flags_request *req,
253 enum pm_qos_req_action action, s32 val)
254{
255 unsigned long irqflags;
256 s32 prev_value, curr_value;
257
258 spin_lock_irqsave(&pm_qos_lock, irqflags);
259
260 prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
261
262 switch (action) {
263 case PM_QOS_REMOVE_REQ:
264 pm_qos_flags_remove_req(pqf, req);
265 break;
266 case PM_QOS_UPDATE_REQ:
267 pm_qos_flags_remove_req(pqf, req);
268 case PM_QOS_ADD_REQ:
269 req->flags = val;
270 INIT_LIST_HEAD(&req->node);
271 list_add_tail(&req->node, &pqf->list);
272 pqf->effective_flags |= val;
273 break;
274 default:
275 /* no action */
276 ;
277 }
278
279 curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
280
281 spin_unlock_irqrestore(&pm_qos_lock, irqflags);
282
283 trace_pm_qos_update_flags(action, prev_value, curr_value);
284 return prev_value != curr_value;
285}
286
287/**
288 * pm_qos_request - returns current system wide qos expectation
289 * @pm_qos_class: identification of which qos value is requested
290 *
291 * This function returns the current target value.
292 */
293int pm_qos_request(int pm_qos_class)
294{
295 return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
296}
297EXPORT_SYMBOL_GPL(pm_qos_request);
298
299int pm_qos_request_active(struct pm_qos_request *req)
300{
301 return req->pm_qos_class != 0;
302}
303EXPORT_SYMBOL_GPL(pm_qos_request_active);
304
305static void __pm_qos_update_request(struct pm_qos_request *req,
306 s32 new_value)
307{
308 trace_pm_qos_update_request(req->pm_qos_class, new_value);
309
310 if (new_value != req->node.prio)
311 pm_qos_update_target(
312 pm_qos_array[req->pm_qos_class]->constraints,
313 &req->node, PM_QOS_UPDATE_REQ, new_value);
314}
315
316/**
317 * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
318 * @work: work struct for the delayed work (timeout)
319 *
320 * This cancels the timeout request by falling back to the default at timeout.
321 */
322static void pm_qos_work_fn(struct work_struct *work)
323{
324 struct pm_qos_request *req = container_of(to_delayed_work(work),
325 struct pm_qos_request,
326 work);
327
328 __pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
329}
330
331/**
332 * pm_qos_add_request - inserts new qos request into the list
333 * @req: pointer to a preallocated handle
334 * @pm_qos_class: identifies which list of qos request to use
335 * @value: defines the qos request
336 *
337 * This function inserts a new entry in the pm_qos_class list of requested qos
338 * performance characteristics. It recomputes the aggregate QoS expectations
339 * for the pm_qos_class of parameters and initializes the pm_qos_request
340 * handle. Caller needs to save this handle for later use in updates and
341 * removal.
342 */
343
344void pm_qos_add_request(struct pm_qos_request *req,
345 int pm_qos_class, s32 value)
346{
347 if (!req) /*guard against callers passing in null */
348 return;
349
350 if (pm_qos_request_active(req)) {
351 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
352 return;
353 }
354 req->pm_qos_class = pm_qos_class;
355 INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
356 trace_pm_qos_add_request(pm_qos_class, value);
357 pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
358 &req->node, PM_QOS_ADD_REQ, value);
359}
360EXPORT_SYMBOL_GPL(pm_qos_add_request);
361
362/**
363 * pm_qos_update_request - modifies an existing qos request
364 * @req : handle to list element holding a pm_qos request to use
365 * @value: defines the qos request
366 *
367 * Updates an existing qos request for the pm_qos_class of parameters along
368 * with updating the target pm_qos_class value.
369 *
370 * Attempts are made to make this code callable on hot code paths.
371 */
372void pm_qos_update_request(struct pm_qos_request *req,
373 s32 new_value)
374{
375 if (!req) /*guard against callers passing in null */
376 return;
377
378 if (!pm_qos_request_active(req)) {
379 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
380 return;
381 }
382
383 cancel_delayed_work_sync(&req->work);
384 __pm_qos_update_request(req, new_value);
385}
386EXPORT_SYMBOL_GPL(pm_qos_update_request);
387
388/**
389 * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
390 * @req : handle to list element holding a pm_qos request to use
391 * @new_value: defines the temporal qos request
392 * @timeout_us: the effective duration of this qos request in usecs.
393 *
394 * After timeout_us, this qos request is cancelled automatically.
395 */
396void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
397 unsigned long timeout_us)
398{
399 if (!req)
400 return;
401 if (WARN(!pm_qos_request_active(req),
402 "%s called for unknown object.", __func__))
403 return;
404
405 cancel_delayed_work_sync(&req->work);
406
407 trace_pm_qos_update_request_timeout(req->pm_qos_class,
408 new_value, timeout_us);
409 if (new_value != req->node.prio)
410 pm_qos_update_target(
411 pm_qos_array[req->pm_qos_class]->constraints,
412 &req->node, PM_QOS_UPDATE_REQ, new_value);
413
414 schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
415}
416
417/**
418 * pm_qos_remove_request - modifies an existing qos request
419 * @req: handle to request list element
420 *
421 * Will remove pm qos request from the list of constraints and
422 * recompute the current target value for the pm_qos_class. Call this
423 * on slow code paths.
424 */
425void pm_qos_remove_request(struct pm_qos_request *req)
426{
427 if (!req) /*guard against callers passing in null */
428 return;
429 /* silent return to keep pcm code cleaner */
430
431 if (!pm_qos_request_active(req)) {
432 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
433 return;
434 }
435
436 cancel_delayed_work_sync(&req->work);
437
438 trace_pm_qos_remove_request(req->pm_qos_class, PM_QOS_DEFAULT_VALUE);
439 pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
440 &req->node, PM_QOS_REMOVE_REQ,
441 PM_QOS_DEFAULT_VALUE);
442 memset(req, 0, sizeof(*req));
443}
444EXPORT_SYMBOL_GPL(pm_qos_remove_request);
445
446/**
447 * pm_qos_add_notifier - sets notification entry for changes to target value
448 * @pm_qos_class: identifies which qos target changes should be notified.
449 * @notifier: notifier block managed by caller.
450 *
451 * will register the notifier into a notification chain that gets called
452 * upon changes to the pm_qos_class target value.
453 */
454int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
455{
456 int retval;
457
458 retval = blocking_notifier_chain_register(
459 pm_qos_array[pm_qos_class]->constraints->notifiers,
460 notifier);
461
462 return retval;
463}
464EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
465
466/**
467 * pm_qos_remove_notifier - deletes notification entry from chain.
468 * @pm_qos_class: identifies which qos target changes are notified.
469 * @notifier: notifier block to be removed.
470 *
471 * will remove the notifier from the notification chain that gets called
472 * upon changes to the pm_qos_class target value.
473 */
474int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
475{
476 int retval;
477
478 retval = blocking_notifier_chain_unregister(
479 pm_qos_array[pm_qos_class]->constraints->notifiers,
480 notifier);
481
482 return retval;
483}
484EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
485
486/* User space interface to PM QoS classes via misc devices */
487static int register_pm_qos_misc(struct pm_qos_object *qos)
488{
489 qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
490 qos->pm_qos_power_miscdev.name = qos->name;
491 qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
492
493 return misc_register(&qos->pm_qos_power_miscdev);
494}
495
496static int find_pm_qos_object_by_minor(int minor)
497{
498 int pm_qos_class;
499
500 for (pm_qos_class = PM_QOS_CPU_DMA_LATENCY;
501 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
502 if (minor ==
503 pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
504 return pm_qos_class;
505 }
506 return -1;
507}
508
509static int pm_qos_power_open(struct inode *inode, struct file *filp)
510{
511 long pm_qos_class;
512
513 pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
514 if (pm_qos_class >= PM_QOS_CPU_DMA_LATENCY) {
515 struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
516 if (!req)
517 return -ENOMEM;
518
519 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
520 filp->private_data = req;
521
522 return 0;
523 }
524 return -EPERM;
525}
526
527static int pm_qos_power_release(struct inode *inode, struct file *filp)
528{
529 struct pm_qos_request *req;
530
531 req = filp->private_data;
532 pm_qos_remove_request(req);
533 kfree(req);
534
535 return 0;
536}
537
538
539static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
540 size_t count, loff_t *f_pos)
541{
542 s32 value;
543 unsigned long flags;
544 struct pm_qos_request *req = filp->private_data;
545
546 if (!req)
547 return -EINVAL;
548 if (!pm_qos_request_active(req))
549 return -EINVAL;
550
551 spin_lock_irqsave(&pm_qos_lock, flags);
552 value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
553 spin_unlock_irqrestore(&pm_qos_lock, flags);
554
555 return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
556}
557
558static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
559 size_t count, loff_t *f_pos)
560{
561 s32 value;
562 struct pm_qos_request *req;
563
564 if (count == sizeof(s32)) {
565 if (copy_from_user(&value, buf, sizeof(s32)))
566 return -EFAULT;
567 } else {
568 int ret;
569
570 ret = kstrtos32_from_user(buf, count, 16, &value);
571 if (ret)
572 return ret;
573 }
574
575 req = filp->private_data;
576 pm_qos_update_request(req, value);
577
578 return count;
579}
580
581
582static int __init pm_qos_power_init(void)
583{
584 int ret = 0;
585 int i;
586
587 BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
588
589 for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) {
590 ret = register_pm_qos_misc(pm_qos_array[i]);
591 if (ret < 0) {
592 printk(KERN_ERR "pm_qos_param: %s setup failed\n",
593 pm_qos_array[i]->name);
594 return ret;
595 }
596 }
597
598 return ret;
599}
600
601late_initcall(pm_qos_power_init);