2 * This module exposes the interface to kernel space for specifying
3 * QoS dependencies. It provides infrastructure for registration of:
5 * Dependents on a QoS value : register requests
6 * Watchers of QoS value : get notified when target QoS value changes
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.
11 * There are 3 basic classes of QoS parameter: latency, timeout, throughput
12 * each have defined units:
14 * timeout: usec <-- currently not used.
15 * throughput: kbs (kilo byte / sec)
17 * There are lists of pm_qos_objects each one wrapping requests, notifiers
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.
27 * Mark Gross <mgross@linux.intel.com>
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>
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>
45 #include <linux/uaccess.h>
46 #include <linux/export.h>
49 * locking rule: all changes to constraints or notifiers lists
50 * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
51 * held, taken with _irqsave. One lock to rule them all
53 struct pm_qos_object {
54 struct pm_qos_constraints *constraints;
55 struct miscdevice pm_qos_power_miscdev;
59 static DEFINE_SPINLOCK(pm_qos_lock);
61 static struct pm_qos_object null_pm_qos;
63 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
64 static struct pm_qos_constraints cpu_dma_constraints = {
65 .list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
66 .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
67 .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
69 .notifiers = &cpu_dma_lat_notifier,
71 static struct pm_qos_object cpu_dma_pm_qos = {
72 .constraints = &cpu_dma_constraints,
73 .name = "cpu_dma_latency",
76 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
77 static struct pm_qos_constraints network_lat_constraints = {
78 .list = PLIST_HEAD_INIT(network_lat_constraints.list),
79 .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
80 .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
82 .notifiers = &network_lat_notifier,
84 static struct pm_qos_object network_lat_pm_qos = {
85 .constraints = &network_lat_constraints,
86 .name = "network_latency",
90 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
91 static struct pm_qos_constraints network_tput_constraints = {
92 .list = PLIST_HEAD_INIT(network_tput_constraints.list),
93 .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
94 .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
96 .notifiers = &network_throughput_notifier,
98 static struct pm_qos_object network_throughput_pm_qos = {
99 .constraints = &network_tput_constraints,
100 .name = "network_throughput",
103 #ifdef CONFIG_CPUQUIET_FRAMEWORK
104 static BLOCKING_NOTIFIER_HEAD(min_online_cpus_notifier);
105 static struct pm_qos_constraints min_online_cpus_constraints = {
106 .list = PLIST_HEAD_INIT(min_online_cpus_constraints.list),
107 .target_value = PM_QOS_MIN_ONLINE_CPUS_DEFAULT_VALUE,
108 .default_value = PM_QOS_MIN_ONLINE_CPUS_DEFAULT_VALUE,
110 .notifiers = &min_online_cpus_notifier,
112 static struct pm_qos_object min_online_cpus_pm_qos = {
113 .constraints = &min_online_cpus_constraints,
114 .name = "min_online_cpus",
117 static BLOCKING_NOTIFIER_HEAD(max_online_cpus_notifier);
118 static struct pm_qos_constraints max_online_cpus_constraints = {
119 .list = PLIST_HEAD_INIT(max_online_cpus_constraints.list),
120 .target_value = PM_QOS_MAX_ONLINE_CPUS_DEFAULT_VALUE,
121 .default_value = PM_QOS_MAX_ONLINE_CPUS_DEFAULT_VALUE,
123 .notifiers = &max_online_cpus_notifier,
125 static struct pm_qos_object max_online_cpus_pm_qos = {
126 .constraints = &max_online_cpus_constraints,
127 .name = "max_online_cpus",
131 static struct pm_qos_object *pm_qos_array[] = {
135 &network_throughput_pm_qos,
136 #ifdef CONFIG_CPUQUIET_FRAMEWORK
137 &min_online_cpus_pm_qos,
138 &max_online_cpus_pm_qos,
142 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
143 size_t count, loff_t *f_pos);
144 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
145 size_t count, loff_t *f_pos);
146 static int pm_qos_power_open(struct inode *inode, struct file *filp);
147 static int pm_qos_power_release(struct inode *inode, struct file *filp);
149 static const struct file_operations pm_qos_power_fops = {
150 .write = pm_qos_power_write,
151 .read = pm_qos_power_read,
152 .open = pm_qos_power_open,
153 .release = pm_qos_power_release,
154 .llseek = noop_llseek,
157 /* unlocked internal variant */
158 static inline int pm_qos_get_value(struct pm_qos_constraints *c)
160 if (plist_head_empty(&c->list))
161 return c->default_value;
165 return plist_first(&c->list)->prio;
168 return plist_last(&c->list)->prio;
171 /* runtime check for not using enum */
173 return PM_QOS_DEFAULT_VALUE;
177 s32 pm_qos_read_value(struct pm_qos_constraints *c)
179 return c->target_value;
182 static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
184 c->target_value = value;
188 * pm_qos_update_target - manages the constraints list and calls the notifiers
190 * @c: constraints data struct
191 * @node: request to add to the list, to update or to remove
192 * @action: action to take on the constraints list
193 * @value: value of the request to add or update
195 * This function returns 1 if the aggregated constraint value has changed, 0
198 int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
199 enum pm_qos_req_action action, int value)
202 int prev_value, curr_value, new_value;
204 spin_lock_irqsave(&pm_qos_lock, flags);
205 prev_value = pm_qos_get_value(c);
206 if (value == PM_QOS_DEFAULT_VALUE)
207 new_value = c->default_value;
212 case PM_QOS_REMOVE_REQ:
213 plist_del(node, &c->list);
215 case PM_QOS_UPDATE_REQ:
217 * to change the list, we atomically remove, reinit
218 * with new value and add, then see if the extremal
221 plist_del(node, &c->list);
223 plist_node_init(node, new_value);
224 plist_add(node, &c->list);
231 curr_value = pm_qos_get_value(c);
232 pm_qos_set_value(c, curr_value);
234 spin_unlock_irqrestore(&pm_qos_lock, flags);
236 if (prev_value != curr_value) {
237 blocking_notifier_call_chain(c->notifiers,
238 (unsigned long)curr_value,
247 * pm_qos_flags_remove_req - Remove device PM QoS flags request.
248 * @pqf: Device PM QoS flags set to remove the request from.
249 * @req: Request to remove from the set.
251 static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
252 struct pm_qos_flags_request *req)
256 list_del(&req->node);
257 list_for_each_entry(req, &pqf->list, node)
260 pqf->effective_flags = val;
264 * pm_qos_update_flags - Update a set of PM QoS flags.
265 * @pqf: Set of flags to update.
266 * @req: Request to add to the set, to modify, or to remove from the set.
267 * @action: Action to take on the set.
268 * @val: Value of the request to add or modify.
270 * Update the given set of PM QoS flags and call notifiers if the aggregate
271 * value has changed. Returns 1 if the aggregate constraint value has changed,
274 bool pm_qos_update_flags(struct pm_qos_flags *pqf,
275 struct pm_qos_flags_request *req,
276 enum pm_qos_req_action action, s32 val)
278 unsigned long irqflags;
279 s32 prev_value, curr_value;
281 spin_lock_irqsave(&pm_qos_lock, irqflags);
283 prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
286 case PM_QOS_REMOVE_REQ:
287 pm_qos_flags_remove_req(pqf, req);
289 case PM_QOS_UPDATE_REQ:
290 pm_qos_flags_remove_req(pqf, req);
293 INIT_LIST_HEAD(&req->node);
294 list_add_tail(&req->node, &pqf->list);
295 pqf->effective_flags |= val;
302 curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
304 spin_unlock_irqrestore(&pm_qos_lock, irqflags);
306 return prev_value != curr_value;
310 * pm_qos_request - returns current system wide qos expectation
311 * @pm_qos_class: identification of which qos value is requested
313 * This function returns the current target value.
315 int pm_qos_request(int pm_qos_class)
317 return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
319 EXPORT_SYMBOL_GPL(pm_qos_request);
321 int pm_qos_request_active(struct pm_qos_request *req)
323 return req->pm_qos_class != 0;
325 EXPORT_SYMBOL_GPL(pm_qos_request_active);
327 static void __pm_qos_update_request(struct pm_qos_request *req,
330 if (new_value != req->node.prio)
331 pm_qos_update_target(
332 pm_qos_array[req->pm_qos_class]->constraints,
333 &req->node, PM_QOS_UPDATE_REQ, new_value);
337 * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
338 * @work: work struct for the delayed work (timeout)
340 * This cancels the timeout request by falling back to the default at timeout.
342 static void pm_qos_work_fn(struct work_struct *work)
344 struct pm_qos_request *req = container_of(to_delayed_work(work),
345 struct pm_qos_request,
348 __pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
352 * pm_qos_add_request - inserts new qos request into the list
353 * @req: pointer to a preallocated handle
354 * @pm_qos_class: identifies which list of qos request to use
355 * @value: defines the qos request
357 * This function inserts a new entry in the pm_qos_class list of requested qos
358 * performance characteristics. It recomputes the aggregate QoS expectations
359 * for the pm_qos_class of parameters and initializes the pm_qos_request
360 * handle. Caller needs to save this handle for later use in updates and
364 void pm_qos_add_request(struct pm_qos_request *req,
365 int pm_qos_class, s32 value)
367 if (!req) /*guard against callers passing in null */
370 if (pm_qos_request_active(req)) {
371 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
374 req->pm_qos_class = pm_qos_class;
375 INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
376 pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
377 &req->node, PM_QOS_ADD_REQ, value);
379 EXPORT_SYMBOL_GPL(pm_qos_add_request);
382 * pm_qos_update_request - modifies an existing qos request
383 * @req : handle to list element holding a pm_qos request to use
384 * @value: defines the qos request
386 * Updates an existing qos request for the pm_qos_class of parameters along
387 * with updating the target pm_qos_class value.
389 * Attempts are made to make this code callable on hot code paths.
391 void pm_qos_update_request(struct pm_qos_request *req,
394 if (!req) /*guard against callers passing in null */
397 if (!pm_qos_request_active(req)) {
398 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
402 cancel_delayed_work_sync(&req->work);
403 __pm_qos_update_request(req, new_value);
405 EXPORT_SYMBOL_GPL(pm_qos_update_request);
408 * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
409 * @req : handle to list element holding a pm_qos request to use
410 * @new_value: defines the temporal qos request
411 * @timeout_us: the effective duration of this qos request in usecs.
413 * After timeout_us, this qos request is cancelled automatically.
415 void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
416 unsigned long timeout_us)
420 if (WARN(!pm_qos_request_active(req),
421 "%s called for unknown object.", __func__))
424 cancel_delayed_work_sync(&req->work);
426 if (new_value != req->node.prio)
427 pm_qos_update_target(
428 pm_qos_array[req->pm_qos_class]->constraints,
429 &req->node, PM_QOS_UPDATE_REQ, new_value);
431 schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
435 * pm_qos_remove_request - modifies an existing qos request
436 * @req: handle to request list element
438 * Will remove pm qos request from the list of constraints and
439 * recompute the current target value for the pm_qos_class. Call this
440 * on slow code paths.
442 void pm_qos_remove_request(struct pm_qos_request *req)
444 if (!req) /*guard against callers passing in null */
446 /* silent return to keep pcm code cleaner */
448 if (!pm_qos_request_active(req)) {
449 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
453 cancel_delayed_work_sync(&req->work);
455 pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
456 &req->node, PM_QOS_REMOVE_REQ,
457 PM_QOS_DEFAULT_VALUE);
458 memset(req, 0, sizeof(*req));
460 EXPORT_SYMBOL_GPL(pm_qos_remove_request);
463 * pm_qos_add_notifier - sets notification entry for changes to target value
464 * @pm_qos_class: identifies which qos target changes should be notified.
465 * @notifier: notifier block managed by caller.
467 * will register the notifier into a notification chain that gets called
468 * upon changes to the pm_qos_class target value.
470 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
474 retval = blocking_notifier_chain_register(
475 pm_qos_array[pm_qos_class]->constraints->notifiers,
480 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
483 * pm_qos_remove_notifier - deletes notification entry from chain.
484 * @pm_qos_class: identifies which qos target changes are notified.
485 * @notifier: notifier block to be removed.
487 * will remove the notifier from the notification chain that gets called
488 * upon changes to the pm_qos_class target value.
490 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
494 retval = blocking_notifier_chain_unregister(
495 pm_qos_array[pm_qos_class]->constraints->notifiers,
500 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
502 /* User space interface to PM QoS classes via misc devices */
503 static int register_pm_qos_misc(struct pm_qos_object *qos)
505 qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
506 qos->pm_qos_power_miscdev.name = qos->name;
507 qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
509 return misc_register(&qos->pm_qos_power_miscdev);
512 static int find_pm_qos_object_by_minor(int minor)
516 for (pm_qos_class = 0;
517 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
519 pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
525 static int pm_qos_power_open(struct inode *inode, struct file *filp)
529 pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
530 if (pm_qos_class >= 0) {
531 struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
535 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
536 filp->private_data = req;
543 static int pm_qos_power_release(struct inode *inode, struct file *filp)
545 struct pm_qos_request *req;
547 req = filp->private_data;
548 pm_qos_remove_request(req);
555 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
556 size_t count, loff_t *f_pos)
560 struct pm_qos_request *req = filp->private_data;
564 if (!pm_qos_request_active(req))
567 spin_lock_irqsave(&pm_qos_lock, flags);
568 value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
569 spin_unlock_irqrestore(&pm_qos_lock, flags);
571 return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
574 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
575 size_t count, loff_t *f_pos)
578 struct pm_qos_request *req;
580 if (count == sizeof(s32)) {
581 if (copy_from_user(&value, buf, sizeof(s32)))
583 } else if (count <= 11) { /* ASCII perhaps? */
584 char ascii_value[11];
585 unsigned long int ulval;
588 if (copy_from_user(ascii_value, buf, count))
592 if (ascii_value[10] == '\n')
593 ascii_value[10] = '\0';
597 ascii_value[count] = '\0';
599 ret = kstrtoul(ascii_value, 16, &ulval);
601 pr_debug("%s, 0x%lx, 0x%x\n", ascii_value, ulval, ret);
604 value = (s32)lower_32_bits(ulval);
609 req = filp->private_data;
610 pm_qos_update_request(req, value);
616 static int __init pm_qos_power_init(void)
621 BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
623 for (i = 1; i < PM_QOS_NUM_CLASSES; i++) {
624 ret = register_pm_qos_misc(pm_qos_array[i]);
626 printk(KERN_ERR "pm_qos_param: %s setup failed\n",
627 pm_qos_array[i]->name);
635 late_initcall(pm_qos_power_init);