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91ff4cb8 JP |
1 | /* |
2 | * Devices PM QoS constraints management | |
3 | * | |
4 | * Copyright (C) 2011 Texas Instruments, Inc. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * | |
11 | * This module exposes the interface to kernel space for specifying | |
12 | * per-device PM QoS dependencies. It provides infrastructure for registration | |
13 | * of: | |
14 | * | |
15 | * Dependents on a QoS value : register requests | |
16 | * Watchers of QoS value : get notified when target QoS value changes | |
17 | * | |
18 | * This QoS design is best effort based. Dependents register their QoS needs. | |
19 | * Watchers register to keep track of the current QoS needs of the system. | |
b66213cd JP |
20 | * Watchers can register different types of notification callbacks: |
21 | * . a per-device notification callback using the dev_pm_qos_*_notifier API. | |
22 | * The notification chain data is stored in the per-device constraint | |
23 | * data struct. | |
24 | * . a system-wide notification callback using the dev_pm_qos_*_global_notifier | |
25 | * API. The notification chain data is stored in a static variable. | |
91ff4cb8 JP |
26 | * |
27 | * Note about the per-device constraint data struct allocation: | |
28 | * . The per-device constraints data struct ptr is tored into the device | |
29 | * dev_pm_info. | |
30 | * . To minimize the data usage by the per-device constraints, the data struct | |
31 | * is only allocated at the first call to dev_pm_qos_add_request. | |
32 | * . The data is later free'd when the device is removed from the system. | |
91ff4cb8 JP |
33 | * . A global mutex protects the constraints users from the data being |
34 | * allocated and free'd. | |
35 | */ | |
36 | ||
37 | #include <linux/pm_qos.h> | |
38 | #include <linux/spinlock.h> | |
39 | #include <linux/slab.h> | |
40 | #include <linux/device.h> | |
41 | #include <linux/mutex.h> | |
1b6bc32f | 42 | #include <linux/export.h> |
91ff4cb8 | 43 | |
85dc0b8a | 44 | #include "power.h" |
91ff4cb8 JP |
45 | |
46 | static DEFINE_MUTEX(dev_pm_qos_mtx); | |
1a9a9152 | 47 | |
b66213cd JP |
48 | static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers); |
49 | ||
1a9a9152 | 50 | /** |
00dc9ad1 RW |
51 | * __dev_pm_qos_read_value - Get PM QoS constraint for a given device. |
52 | * @dev: Device to get the PM QoS constraint value for. | |
53 | * | |
54 | * This routine must be called with dev->power.lock held. | |
55 | */ | |
56 | s32 __dev_pm_qos_read_value(struct device *dev) | |
57 | { | |
58 | struct pm_qos_constraints *c = dev->power.constraints; | |
59 | ||
60 | return c ? pm_qos_read_value(c) : 0; | |
61 | } | |
62 | ||
63 | /** | |
64 | * dev_pm_qos_read_value - Get PM QoS constraint for a given device (locked). | |
1a9a9152 RW |
65 | * @dev: Device to get the PM QoS constraint value for. |
66 | */ | |
67 | s32 dev_pm_qos_read_value(struct device *dev) | |
68 | { | |
1a9a9152 | 69 | unsigned long flags; |
00dc9ad1 | 70 | s32 ret; |
1a9a9152 RW |
71 | |
72 | spin_lock_irqsave(&dev->power.lock, flags); | |
00dc9ad1 | 73 | ret = __dev_pm_qos_read_value(dev); |
1a9a9152 RW |
74 | spin_unlock_irqrestore(&dev->power.lock, flags); |
75 | ||
76 | return ret; | |
77 | } | |
78 | ||
b66213cd JP |
79 | /* |
80 | * apply_constraint | |
81 | * @req: constraint request to apply | |
82 | * @action: action to perform add/update/remove, of type enum pm_qos_req_action | |
83 | * @value: defines the qos request | |
84 | * | |
85 | * Internal function to update the constraints list using the PM QoS core | |
86 | * code and if needed call the per-device and the global notification | |
87 | * callbacks | |
88 | */ | |
89 | static int apply_constraint(struct dev_pm_qos_request *req, | |
90 | enum pm_qos_req_action action, int value) | |
91 | { | |
92 | int ret, curr_value; | |
93 | ||
94 | ret = pm_qos_update_target(req->dev->power.constraints, | |
95 | &req->node, action, value); | |
96 | ||
97 | if (ret) { | |
98 | /* Call the global callbacks if needed */ | |
99 | curr_value = pm_qos_read_value(req->dev->power.constraints); | |
100 | blocking_notifier_call_chain(&dev_pm_notifiers, | |
101 | (unsigned long)curr_value, | |
102 | req); | |
103 | } | |
104 | ||
105 | return ret; | |
106 | } | |
91ff4cb8 JP |
107 | |
108 | /* | |
109 | * dev_pm_qos_constraints_allocate | |
110 | * @dev: device to allocate data for | |
111 | * | |
112 | * Called at the first call to add_request, for constraint data allocation | |
113 | * Must be called with the dev_pm_qos_mtx mutex held | |
114 | */ | |
115 | static int dev_pm_qos_constraints_allocate(struct device *dev) | |
116 | { | |
117 | struct pm_qos_constraints *c; | |
118 | struct blocking_notifier_head *n; | |
119 | ||
120 | c = kzalloc(sizeof(*c), GFP_KERNEL); | |
121 | if (!c) | |
122 | return -ENOMEM; | |
123 | ||
124 | n = kzalloc(sizeof(*n), GFP_KERNEL); | |
125 | if (!n) { | |
126 | kfree(c); | |
127 | return -ENOMEM; | |
128 | } | |
129 | BLOCKING_INIT_NOTIFIER_HEAD(n); | |
130 | ||
1a9a9152 RW |
131 | plist_head_init(&c->list); |
132 | c->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE; | |
133 | c->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE; | |
134 | c->type = PM_QOS_MIN; | |
135 | c->notifiers = n; | |
136 | ||
137 | spin_lock_irq(&dev->power.lock); | |
91ff4cb8 | 138 | dev->power.constraints = c; |
1a9a9152 | 139 | spin_unlock_irq(&dev->power.lock); |
91ff4cb8 JP |
140 | |
141 | return 0; | |
142 | } | |
143 | ||
144 | /** | |
1a9a9152 | 145 | * dev_pm_qos_constraints_init - Initalize device's PM QoS constraints pointer. |
91ff4cb8 JP |
146 | * @dev: target device |
147 | * | |
1a9a9152 RW |
148 | * Called from the device PM subsystem during device insertion under |
149 | * device_pm_lock(). | |
91ff4cb8 JP |
150 | */ |
151 | void dev_pm_qos_constraints_init(struct device *dev) | |
152 | { | |
153 | mutex_lock(&dev_pm_qos_mtx); | |
1a9a9152 RW |
154 | dev->power.constraints = NULL; |
155 | dev->power.power_state = PMSG_ON; | |
91ff4cb8 JP |
156 | mutex_unlock(&dev_pm_qos_mtx); |
157 | } | |
158 | ||
159 | /** | |
160 | * dev_pm_qos_constraints_destroy | |
161 | * @dev: target device | |
162 | * | |
1a9a9152 | 163 | * Called from the device PM subsystem on device removal under device_pm_lock(). |
91ff4cb8 JP |
164 | */ |
165 | void dev_pm_qos_constraints_destroy(struct device *dev) | |
166 | { | |
167 | struct dev_pm_qos_request *req, *tmp; | |
1a9a9152 | 168 | struct pm_qos_constraints *c; |
91ff4cb8 | 169 | |
85dc0b8a RW |
170 | /* |
171 | * If the device's PM QoS resume latency limit has been exposed to user | |
172 | * space, it has to be hidden at this point. | |
173 | */ | |
174 | dev_pm_qos_hide_latency_limit(dev); | |
175 | ||
91ff4cb8 JP |
176 | mutex_lock(&dev_pm_qos_mtx); |
177 | ||
1a9a9152 RW |
178 | dev->power.power_state = PMSG_INVALID; |
179 | c = dev->power.constraints; | |
180 | if (!c) | |
181 | goto out; | |
91ff4cb8 | 182 | |
1a9a9152 RW |
183 | /* Flush the constraints list for the device */ |
184 | plist_for_each_entry_safe(req, tmp, &c->list, node) { | |
185 | /* | |
186 | * Update constraints list and call the notification | |
187 | * callbacks if needed | |
188 | */ | |
189 | apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE); | |
190 | memset(req, 0, sizeof(*req)); | |
91ff4cb8 | 191 | } |
91ff4cb8 | 192 | |
1a9a9152 RW |
193 | spin_lock_irq(&dev->power.lock); |
194 | dev->power.constraints = NULL; | |
195 | spin_unlock_irq(&dev->power.lock); | |
196 | ||
197 | kfree(c->notifiers); | |
198 | kfree(c); | |
199 | ||
200 | out: | |
91ff4cb8 JP |
201 | mutex_unlock(&dev_pm_qos_mtx); |
202 | } | |
203 | ||
204 | /** | |
205 | * dev_pm_qos_add_request - inserts new qos request into the list | |
206 | * @dev: target device for the constraint | |
207 | * @req: pointer to a preallocated handle | |
208 | * @value: defines the qos request | |
209 | * | |
210 | * This function inserts a new entry in the device constraints list of | |
211 | * requested qos performance characteristics. It recomputes the aggregate | |
212 | * QoS expectations of parameters and initializes the dev_pm_qos_request | |
213 | * handle. Caller needs to save this handle for later use in updates and | |
214 | * removal. | |
215 | * | |
216 | * Returns 1 if the aggregated constraint value has changed, | |
217 | * 0 if the aggregated constraint value has not changed, | |
1a9a9152 RW |
218 | * -EINVAL in case of wrong parameters, -ENOMEM if there's not enough memory |
219 | * to allocate for data structures, -ENODEV if the device has just been removed | |
220 | * from the system. | |
91ff4cb8 JP |
221 | */ |
222 | int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req, | |
b66213cd | 223 | s32 value) |
91ff4cb8 JP |
224 | { |
225 | int ret = 0; | |
226 | ||
227 | if (!dev || !req) /*guard against callers passing in null */ | |
228 | return -EINVAL; | |
229 | ||
af4c720e GL |
230 | if (WARN(dev_pm_qos_request_active(req), |
231 | "%s() called for already added request\n", __func__)) | |
91ff4cb8 | 232 | return -EINVAL; |
91ff4cb8 | 233 | |
91ff4cb8 JP |
234 | req->dev = dev; |
235 | ||
1a9a9152 | 236 | mutex_lock(&dev_pm_qos_mtx); |
91ff4cb8 | 237 | |
1a9a9152 RW |
238 | if (!dev->power.constraints) { |
239 | if (dev->power.power_state.event == PM_EVENT_INVALID) { | |
240 | /* The device has been removed from the system. */ | |
241 | req->dev = NULL; | |
242 | ret = -ENODEV; | |
243 | goto out; | |
244 | } else { | |
245 | /* | |
246 | * Allocate the constraints data on the first call to | |
247 | * add_request, i.e. only if the data is not already | |
248 | * allocated and if the device has not been removed. | |
249 | */ | |
250 | ret = dev_pm_qos_constraints_allocate(dev); | |
251 | } | |
252 | } | |
91ff4cb8 JP |
253 | |
254 | if (!ret) | |
b66213cd | 255 | ret = apply_constraint(req, PM_QOS_ADD_REQ, value); |
91ff4cb8 | 256 | |
1a9a9152 | 257 | out: |
91ff4cb8 | 258 | mutex_unlock(&dev_pm_qos_mtx); |
1a9a9152 | 259 | |
91ff4cb8 JP |
260 | return ret; |
261 | } | |
262 | EXPORT_SYMBOL_GPL(dev_pm_qos_add_request); | |
263 | ||
264 | /** | |
265 | * dev_pm_qos_update_request - modifies an existing qos request | |
266 | * @req : handle to list element holding a dev_pm_qos request to use | |
267 | * @new_value: defines the qos request | |
268 | * | |
269 | * Updates an existing dev PM qos request along with updating the | |
270 | * target value. | |
271 | * | |
272 | * Attempts are made to make this code callable on hot code paths. | |
273 | * | |
274 | * Returns 1 if the aggregated constraint value has changed, | |
275 | * 0 if the aggregated constraint value has not changed, | |
276 | * -EINVAL in case of wrong parameters, -ENODEV if the device has been | |
277 | * removed from the system | |
278 | */ | |
279 | int dev_pm_qos_update_request(struct dev_pm_qos_request *req, | |
280 | s32 new_value) | |
281 | { | |
282 | int ret = 0; | |
283 | ||
284 | if (!req) /*guard against callers passing in null */ | |
285 | return -EINVAL; | |
286 | ||
af4c720e GL |
287 | if (WARN(!dev_pm_qos_request_active(req), |
288 | "%s() called for unknown object\n", __func__)) | |
91ff4cb8 | 289 | return -EINVAL; |
91ff4cb8 JP |
290 | |
291 | mutex_lock(&dev_pm_qos_mtx); | |
292 | ||
1a9a9152 | 293 | if (req->dev->power.constraints) { |
91ff4cb8 | 294 | if (new_value != req->node.prio) |
b66213cd JP |
295 | ret = apply_constraint(req, PM_QOS_UPDATE_REQ, |
296 | new_value); | |
91ff4cb8 JP |
297 | } else { |
298 | /* Return if the device has been removed */ | |
299 | ret = -ENODEV; | |
300 | } | |
301 | ||
302 | mutex_unlock(&dev_pm_qos_mtx); | |
303 | return ret; | |
304 | } | |
305 | EXPORT_SYMBOL_GPL(dev_pm_qos_update_request); | |
306 | ||
307 | /** | |
308 | * dev_pm_qos_remove_request - modifies an existing qos request | |
309 | * @req: handle to request list element | |
310 | * | |
311 | * Will remove pm qos request from the list of constraints and | |
312 | * recompute the current target value. Call this on slow code paths. | |
313 | * | |
314 | * Returns 1 if the aggregated constraint value has changed, | |
315 | * 0 if the aggregated constraint value has not changed, | |
316 | * -EINVAL in case of wrong parameters, -ENODEV if the device has been | |
317 | * removed from the system | |
318 | */ | |
319 | int dev_pm_qos_remove_request(struct dev_pm_qos_request *req) | |
320 | { | |
321 | int ret = 0; | |
322 | ||
323 | if (!req) /*guard against callers passing in null */ | |
324 | return -EINVAL; | |
325 | ||
af4c720e GL |
326 | if (WARN(!dev_pm_qos_request_active(req), |
327 | "%s() called for unknown object\n", __func__)) | |
91ff4cb8 | 328 | return -EINVAL; |
91ff4cb8 JP |
329 | |
330 | mutex_lock(&dev_pm_qos_mtx); | |
331 | ||
1a9a9152 | 332 | if (req->dev->power.constraints) { |
b66213cd JP |
333 | ret = apply_constraint(req, PM_QOS_REMOVE_REQ, |
334 | PM_QOS_DEFAULT_VALUE); | |
91ff4cb8 JP |
335 | memset(req, 0, sizeof(*req)); |
336 | } else { | |
337 | /* Return if the device has been removed */ | |
338 | ret = -ENODEV; | |
339 | } | |
340 | ||
341 | mutex_unlock(&dev_pm_qos_mtx); | |
342 | return ret; | |
343 | } | |
344 | EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request); | |
345 | ||
346 | /** | |
347 | * dev_pm_qos_add_notifier - sets notification entry for changes to target value | |
348 | * of per-device PM QoS constraints | |
349 | * | |
350 | * @dev: target device for the constraint | |
351 | * @notifier: notifier block managed by caller. | |
352 | * | |
353 | * Will register the notifier into a notification chain that gets called | |
354 | * upon changes to the target value for the device. | |
23e0fc5a RW |
355 | * |
356 | * If the device's constraints object doesn't exist when this routine is called, | |
357 | * it will be created (or error code will be returned if that fails). | |
91ff4cb8 JP |
358 | */ |
359 | int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier) | |
360 | { | |
23e0fc5a | 361 | int ret = 0; |
91ff4cb8 JP |
362 | |
363 | mutex_lock(&dev_pm_qos_mtx); | |
364 | ||
23e0fc5a RW |
365 | if (!dev->power.constraints) |
366 | ret = dev->power.power_state.event != PM_EVENT_INVALID ? | |
367 | dev_pm_qos_constraints_allocate(dev) : -ENODEV; | |
368 | ||
369 | if (!ret) | |
370 | ret = blocking_notifier_chain_register( | |
371 | dev->power.constraints->notifiers, notifier); | |
91ff4cb8 | 372 | |
91ff4cb8 | 373 | mutex_unlock(&dev_pm_qos_mtx); |
23e0fc5a | 374 | return ret; |
91ff4cb8 JP |
375 | } |
376 | EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier); | |
377 | ||
378 | /** | |
379 | * dev_pm_qos_remove_notifier - deletes notification for changes to target value | |
380 | * of per-device PM QoS constraints | |
381 | * | |
382 | * @dev: target device for the constraint | |
383 | * @notifier: notifier block to be removed. | |
384 | * | |
385 | * Will remove the notifier from the notification chain that gets called | |
386 | * upon changes to the target value. | |
387 | */ | |
388 | int dev_pm_qos_remove_notifier(struct device *dev, | |
389 | struct notifier_block *notifier) | |
390 | { | |
391 | int retval = 0; | |
392 | ||
393 | mutex_lock(&dev_pm_qos_mtx); | |
394 | ||
1a9a9152 RW |
395 | /* Silently return if the constraints object is not present. */ |
396 | if (dev->power.constraints) | |
397 | retval = blocking_notifier_chain_unregister( | |
398 | dev->power.constraints->notifiers, | |
399 | notifier); | |
91ff4cb8 | 400 | |
91ff4cb8 JP |
401 | mutex_unlock(&dev_pm_qos_mtx); |
402 | return retval; | |
403 | } | |
404 | EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier); | |
b66213cd JP |
405 | |
406 | /** | |
407 | * dev_pm_qos_add_global_notifier - sets notification entry for changes to | |
408 | * target value of the PM QoS constraints for any device | |
409 | * | |
410 | * @notifier: notifier block managed by caller. | |
411 | * | |
412 | * Will register the notifier into a notification chain that gets called | |
413 | * upon changes to the target value for any device. | |
414 | */ | |
415 | int dev_pm_qos_add_global_notifier(struct notifier_block *notifier) | |
416 | { | |
417 | return blocking_notifier_chain_register(&dev_pm_notifiers, notifier); | |
418 | } | |
419 | EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier); | |
420 | ||
421 | /** | |
422 | * dev_pm_qos_remove_global_notifier - deletes notification for changes to | |
423 | * target value of PM QoS constraints for any device | |
424 | * | |
425 | * @notifier: notifier block to be removed. | |
426 | * | |
427 | * Will remove the notifier from the notification chain that gets called | |
428 | * upon changes to the target value for any device. | |
429 | */ | |
430 | int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier) | |
431 | { | |
432 | return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier); | |
433 | } | |
434 | EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier); | |
40a5f8be RW |
435 | |
436 | /** | |
437 | * dev_pm_qos_add_ancestor_request - Add PM QoS request for device's ancestor. | |
438 | * @dev: Device whose ancestor to add the request for. | |
439 | * @req: Pointer to the preallocated handle. | |
440 | * @value: Constraint latency value. | |
441 | */ | |
442 | int dev_pm_qos_add_ancestor_request(struct device *dev, | |
443 | struct dev_pm_qos_request *req, s32 value) | |
444 | { | |
445 | struct device *ancestor = dev->parent; | |
446 | int error = -ENODEV; | |
447 | ||
448 | while (ancestor && !ancestor->power.ignore_children) | |
449 | ancestor = ancestor->parent; | |
450 | ||
451 | if (ancestor) | |
452 | error = dev_pm_qos_add_request(ancestor, req, value); | |
453 | ||
454 | if (error) | |
455 | req->dev = NULL; | |
456 | ||
457 | return error; | |
458 | } | |
459 | EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request); | |
85dc0b8a RW |
460 | |
461 | #ifdef CONFIG_PM_RUNTIME | |
462 | static void __dev_pm_qos_drop_user_request(struct device *dev) | |
463 | { | |
464 | dev_pm_qos_remove_request(dev->power.pq_req); | |
ad0446eb | 465 | dev->power.pq_req = NULL; |
85dc0b8a RW |
466 | } |
467 | ||
468 | /** | |
469 | * dev_pm_qos_expose_latency_limit - Expose PM QoS latency limit to user space. | |
470 | * @dev: Device whose PM QoS latency limit is to be exposed to user space. | |
471 | * @value: Initial value of the latency limit. | |
472 | */ | |
473 | int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value) | |
474 | { | |
475 | struct dev_pm_qos_request *req; | |
476 | int ret; | |
477 | ||
478 | if (!device_is_registered(dev) || value < 0) | |
479 | return -EINVAL; | |
480 | ||
481 | if (dev->power.pq_req) | |
482 | return -EEXIST; | |
483 | ||
484 | req = kzalloc(sizeof(*req), GFP_KERNEL); | |
485 | if (!req) | |
486 | return -ENOMEM; | |
487 | ||
488 | ret = dev_pm_qos_add_request(dev, req, value); | |
489 | if (ret < 0) | |
490 | return ret; | |
491 | ||
492 | dev->power.pq_req = req; | |
493 | ret = pm_qos_sysfs_add(dev); | |
494 | if (ret) | |
495 | __dev_pm_qos_drop_user_request(dev); | |
496 | ||
497 | return ret; | |
498 | } | |
499 | EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_limit); | |
500 | ||
501 | /** | |
502 | * dev_pm_qos_hide_latency_limit - Hide PM QoS latency limit from user space. | |
503 | * @dev: Device whose PM QoS latency limit is to be hidden from user space. | |
504 | */ | |
505 | void dev_pm_qos_hide_latency_limit(struct device *dev) | |
506 | { | |
507 | if (dev->power.pq_req) { | |
508 | pm_qos_sysfs_remove(dev); | |
509 | __dev_pm_qos_drop_user_request(dev); | |
510 | } | |
511 | } | |
512 | EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit); | |
513 | #endif /* CONFIG_PM_RUNTIME */ |