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>
47 #include <trace/events/power.h>
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
54 struct pm_qos_object
{
55 struct pm_qos_constraints
*constraints
;
56 struct miscdevice pm_qos_power_miscdev
;
60 static DEFINE_SPINLOCK(pm_qos_lock
);
62 static struct pm_qos_object null_pm_qos
;
64 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier
);
65 static 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
,
70 .notifiers
= &cpu_dma_lat_notifier
,
72 static struct pm_qos_object cpu_dma_pm_qos
= {
73 .constraints
= &cpu_dma_constraints
,
74 .name
= "cpu_dma_latency",
77 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier
);
78 static struct pm_qos_constraints network_lat_constraints
= {
79 .list
= PLIST_HEAD_INIT(network_lat_constraints
.list
),
80 .target_value
= PM_QOS_NETWORK_LAT_DEFAULT_VALUE
,
81 .default_value
= PM_QOS_NETWORK_LAT_DEFAULT_VALUE
,
83 .notifiers
= &network_lat_notifier
,
85 static struct pm_qos_object network_lat_pm_qos
= {
86 .constraints
= &network_lat_constraints
,
87 .name
= "network_latency",
91 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier
);
92 static struct pm_qos_constraints network_tput_constraints
= {
93 .list
= PLIST_HEAD_INIT(network_tput_constraints
.list
),
94 .target_value
= PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE
,
95 .default_value
= PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE
,
97 .notifiers
= &network_throughput_notifier
,
99 static struct pm_qos_object network_throughput_pm_qos
= {
100 .constraints
= &network_tput_constraints
,
101 .name
= "network_throughput",
105 static struct pm_qos_object
*pm_qos_array
[] = {
109 &network_throughput_pm_qos
112 static ssize_t
pm_qos_power_write(struct file
*filp
, const char __user
*buf
,
113 size_t count
, loff_t
*f_pos
);
114 static ssize_t
pm_qos_power_read(struct file
*filp
, char __user
*buf
,
115 size_t count
, loff_t
*f_pos
);
116 static int pm_qos_power_open(struct inode
*inode
, struct file
*filp
);
117 static int pm_qos_power_release(struct inode
*inode
, struct file
*filp
);
119 static const struct file_operations pm_qos_power_fops
= {
120 .write
= pm_qos_power_write
,
121 .read
= pm_qos_power_read
,
122 .open
= pm_qos_power_open
,
123 .release
= pm_qos_power_release
,
124 .llseek
= noop_llseek
,
127 /* unlocked internal variant */
128 static inline int pm_qos_get_value(struct pm_qos_constraints
*c
)
130 if (plist_head_empty(&c
->list
))
131 return c
->default_value
;
135 return plist_first(&c
->list
)->prio
;
138 return plist_last(&c
->list
)->prio
;
141 /* runtime check for not using enum */
143 return PM_QOS_DEFAULT_VALUE
;
147 s32
pm_qos_read_value(struct pm_qos_constraints
*c
)
149 return c
->target_value
;
152 static inline void pm_qos_set_value(struct pm_qos_constraints
*c
, s32 value
)
154 c
->target_value
= value
;
158 * pm_qos_update_target - manages the constraints list and calls the notifiers
160 * @c: constraints data struct
161 * @node: request to add to the list, to update or to remove
162 * @action: action to take on the constraints list
163 * @value: value of the request to add or update
165 * This function returns 1 if the aggregated constraint value has changed, 0
168 int pm_qos_update_target(struct pm_qos_constraints
*c
, struct plist_node
*node
,
169 enum pm_qos_req_action action
, int value
)
172 int prev_value
, curr_value
, new_value
;
174 spin_lock_irqsave(&pm_qos_lock
, flags
);
175 prev_value
= pm_qos_get_value(c
);
176 if (value
== PM_QOS_DEFAULT_VALUE
)
177 new_value
= c
->default_value
;
182 case PM_QOS_REMOVE_REQ
:
183 plist_del(node
, &c
->list
);
185 case PM_QOS_UPDATE_REQ
:
187 * to change the list, we atomically remove, reinit
188 * with new value and add, then see if the extremal
191 plist_del(node
, &c
->list
);
193 plist_node_init(node
, new_value
);
194 plist_add(node
, &c
->list
);
201 curr_value
= pm_qos_get_value(c
);
202 pm_qos_set_value(c
, curr_value
);
204 spin_unlock_irqrestore(&pm_qos_lock
, flags
);
206 trace_pm_qos_update_target(action
, prev_value
, curr_value
);
207 if (prev_value
!= curr_value
) {
208 blocking_notifier_call_chain(c
->notifiers
,
209 (unsigned long)curr_value
,
218 * pm_qos_flags_remove_req - Remove device PM QoS flags request.
219 * @pqf: Device PM QoS flags set to remove the request from.
220 * @req: Request to remove from the set.
222 static void pm_qos_flags_remove_req(struct pm_qos_flags
*pqf
,
223 struct pm_qos_flags_request
*req
)
227 list_del(&req
->node
);
228 list_for_each_entry(req
, &pqf
->list
, node
)
231 pqf
->effective_flags
= val
;
235 * pm_qos_update_flags - Update a set of PM QoS flags.
236 * @pqf: Set of flags to update.
237 * @req: Request to add to the set, to modify, or to remove from the set.
238 * @action: Action to take on the set.
239 * @val: Value of the request to add or modify.
241 * Update the given set of PM QoS flags and call notifiers if the aggregate
242 * value has changed. Returns 1 if the aggregate constraint value has changed,
245 bool pm_qos_update_flags(struct pm_qos_flags
*pqf
,
246 struct pm_qos_flags_request
*req
,
247 enum pm_qos_req_action action
, s32 val
)
249 unsigned long irqflags
;
250 s32 prev_value
, curr_value
;
252 spin_lock_irqsave(&pm_qos_lock
, irqflags
);
254 prev_value
= list_empty(&pqf
->list
) ? 0 : pqf
->effective_flags
;
257 case PM_QOS_REMOVE_REQ
:
258 pm_qos_flags_remove_req(pqf
, req
);
260 case PM_QOS_UPDATE_REQ
:
261 pm_qos_flags_remove_req(pqf
, req
);
264 INIT_LIST_HEAD(&req
->node
);
265 list_add_tail(&req
->node
, &pqf
->list
);
266 pqf
->effective_flags
|= val
;
273 curr_value
= list_empty(&pqf
->list
) ? 0 : pqf
->effective_flags
;
275 spin_unlock_irqrestore(&pm_qos_lock
, irqflags
);
277 trace_pm_qos_update_flags(action
, prev_value
, curr_value
);
278 return prev_value
!= curr_value
;
282 * pm_qos_request - returns current system wide qos expectation
283 * @pm_qos_class: identification of which qos value is requested
285 * This function returns the current target value.
287 int pm_qos_request(int pm_qos_class
)
289 return pm_qos_read_value(pm_qos_array
[pm_qos_class
]->constraints
);
291 EXPORT_SYMBOL_GPL(pm_qos_request
);
293 int pm_qos_request_active(struct pm_qos_request
*req
)
295 return req
->pm_qos_class
!= 0;
297 EXPORT_SYMBOL_GPL(pm_qos_request_active
);
300 * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
301 * @work: work struct for the delayed work (timeout)
303 * This cancels the timeout request by falling back to the default at timeout.
305 static void pm_qos_work_fn(struct work_struct
*work
)
307 struct pm_qos_request
*req
= container_of(to_delayed_work(work
),
308 struct pm_qos_request
,
311 pm_qos_update_request(req
, PM_QOS_DEFAULT_VALUE
);
315 * pm_qos_add_request - inserts new qos request into the list
316 * @req: pointer to a preallocated handle
317 * @pm_qos_class: identifies which list of qos request to use
318 * @value: defines the qos request
320 * This function inserts a new entry in the pm_qos_class list of requested qos
321 * performance characteristics. It recomputes the aggregate QoS expectations
322 * for the pm_qos_class of parameters and initializes the pm_qos_request
323 * handle. Caller needs to save this handle for later use in updates and
327 void pm_qos_add_request(struct pm_qos_request
*req
,
328 int pm_qos_class
, s32 value
)
330 if (!req
) /*guard against callers passing in null */
333 if (pm_qos_request_active(req
)) {
334 WARN(1, KERN_ERR
"pm_qos_add_request() called for already added request\n");
337 req
->pm_qos_class
= pm_qos_class
;
338 INIT_DELAYED_WORK(&req
->work
, pm_qos_work_fn
);
339 trace_pm_qos_add_request(pm_qos_class
, value
);
340 pm_qos_update_target(pm_qos_array
[pm_qos_class
]->constraints
,
341 &req
->node
, PM_QOS_ADD_REQ
, value
);
343 EXPORT_SYMBOL_GPL(pm_qos_add_request
);
346 * pm_qos_update_request - modifies an existing qos request
347 * @req : handle to list element holding a pm_qos request to use
348 * @value: defines the qos request
350 * Updates an existing qos request for the pm_qos_class of parameters along
351 * with updating the target pm_qos_class value.
353 * Attempts are made to make this code callable on hot code paths.
355 void pm_qos_update_request(struct pm_qos_request
*req
,
358 if (!req
) /*guard against callers passing in null */
361 if (!pm_qos_request_active(req
)) {
362 WARN(1, KERN_ERR
"pm_qos_update_request() called for unknown object\n");
366 cancel_delayed_work_sync(&req
->work
);
368 trace_pm_qos_update_request(req
->pm_qos_class
, new_value
);
369 if (new_value
!= req
->node
.prio
)
370 pm_qos_update_target(
371 pm_qos_array
[req
->pm_qos_class
]->constraints
,
372 &req
->node
, PM_QOS_UPDATE_REQ
, new_value
);
374 EXPORT_SYMBOL_GPL(pm_qos_update_request
);
377 * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
378 * @req : handle to list element holding a pm_qos request to use
379 * @new_value: defines the temporal qos request
380 * @timeout_us: the effective duration of this qos request in usecs.
382 * After timeout_us, this qos request is cancelled automatically.
384 void pm_qos_update_request_timeout(struct pm_qos_request
*req
, s32 new_value
,
385 unsigned long timeout_us
)
389 if (WARN(!pm_qos_request_active(req
),
390 "%s called for unknown object.", __func__
))
393 cancel_delayed_work_sync(&req
->work
);
395 trace_pm_qos_update_request_timeout(req
->pm_qos_class
,
396 new_value
, timeout_us
);
397 if (new_value
!= req
->node
.prio
)
398 pm_qos_update_target(
399 pm_qos_array
[req
->pm_qos_class
]->constraints
,
400 &req
->node
, PM_QOS_UPDATE_REQ
, new_value
);
402 schedule_delayed_work(&req
->work
, usecs_to_jiffies(timeout_us
));
406 * pm_qos_remove_request - modifies an existing qos request
407 * @req: handle to request list element
409 * Will remove pm qos request from the list of constraints and
410 * recompute the current target value for the pm_qos_class. Call this
411 * on slow code paths.
413 void pm_qos_remove_request(struct pm_qos_request
*req
)
415 if (!req
) /*guard against callers passing in null */
417 /* silent return to keep pcm code cleaner */
419 if (!pm_qos_request_active(req
)) {
420 WARN(1, KERN_ERR
"pm_qos_remove_request() called for unknown object\n");
424 cancel_delayed_work_sync(&req
->work
);
426 trace_pm_qos_remove_request(req
->pm_qos_class
, PM_QOS_DEFAULT_VALUE
);
427 pm_qos_update_target(pm_qos_array
[req
->pm_qos_class
]->constraints
,
428 &req
->node
, PM_QOS_REMOVE_REQ
,
429 PM_QOS_DEFAULT_VALUE
);
430 memset(req
, 0, sizeof(*req
));
432 EXPORT_SYMBOL_GPL(pm_qos_remove_request
);
435 * pm_qos_add_notifier - sets notification entry for changes to target value
436 * @pm_qos_class: identifies which qos target changes should be notified.
437 * @notifier: notifier block managed by caller.
439 * will register the notifier into a notification chain that gets called
440 * upon changes to the pm_qos_class target value.
442 int pm_qos_add_notifier(int pm_qos_class
, struct notifier_block
*notifier
)
446 retval
= blocking_notifier_chain_register(
447 pm_qos_array
[pm_qos_class
]->constraints
->notifiers
,
452 EXPORT_SYMBOL_GPL(pm_qos_add_notifier
);
455 * pm_qos_remove_notifier - deletes notification entry from chain.
456 * @pm_qos_class: identifies which qos target changes are notified.
457 * @notifier: notifier block to be removed.
459 * will remove the notifier from the notification chain that gets called
460 * upon changes to the pm_qos_class target value.
462 int pm_qos_remove_notifier(int pm_qos_class
, struct notifier_block
*notifier
)
466 retval
= blocking_notifier_chain_unregister(
467 pm_qos_array
[pm_qos_class
]->constraints
->notifiers
,
472 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier
);
474 /* User space interface to PM QoS classes via misc devices */
475 static int register_pm_qos_misc(struct pm_qos_object
*qos
)
477 qos
->pm_qos_power_miscdev
.minor
= MISC_DYNAMIC_MINOR
;
478 qos
->pm_qos_power_miscdev
.name
= qos
->name
;
479 qos
->pm_qos_power_miscdev
.fops
= &pm_qos_power_fops
;
481 return misc_register(&qos
->pm_qos_power_miscdev
);
484 static int find_pm_qos_object_by_minor(int minor
)
488 for (pm_qos_class
= PM_QOS_CPU_DMA_LATENCY
;
489 pm_qos_class
< PM_QOS_NUM_CLASSES
; pm_qos_class
++) {
491 pm_qos_array
[pm_qos_class
]->pm_qos_power_miscdev
.minor
)
497 static int pm_qos_power_open(struct inode
*inode
, struct file
*filp
)
501 pm_qos_class
= find_pm_qos_object_by_minor(iminor(inode
));
502 if (pm_qos_class
>= PM_QOS_CPU_DMA_LATENCY
) {
503 struct pm_qos_request
*req
= kzalloc(sizeof(*req
), GFP_KERNEL
);
507 pm_qos_add_request(req
, pm_qos_class
, PM_QOS_DEFAULT_VALUE
);
508 filp
->private_data
= req
;
515 static int pm_qos_power_release(struct inode
*inode
, struct file
*filp
)
517 struct pm_qos_request
*req
;
519 req
= filp
->private_data
;
520 pm_qos_remove_request(req
);
527 static ssize_t
pm_qos_power_read(struct file
*filp
, char __user
*buf
,
528 size_t count
, loff_t
*f_pos
)
532 struct pm_qos_request
*req
= filp
->private_data
;
536 if (!pm_qos_request_active(req
))
539 spin_lock_irqsave(&pm_qos_lock
, flags
);
540 value
= pm_qos_get_value(pm_qos_array
[req
->pm_qos_class
]->constraints
);
541 spin_unlock_irqrestore(&pm_qos_lock
, flags
);
543 return simple_read_from_buffer(buf
, count
, f_pos
, &value
, sizeof(s32
));
546 static ssize_t
pm_qos_power_write(struct file
*filp
, const char __user
*buf
,
547 size_t count
, loff_t
*f_pos
)
550 struct pm_qos_request
*req
;
552 if (count
== sizeof(s32
)) {
553 if (copy_from_user(&value
, buf
, sizeof(s32
)))
555 } else if (count
<= 11) { /* ASCII perhaps? */
556 char ascii_value
[11];
557 unsigned long int ulval
;
560 if (copy_from_user(ascii_value
, buf
, count
))
564 if (ascii_value
[10] == '\n')
565 ascii_value
[10] = '\0';
569 ascii_value
[count
] = '\0';
571 ret
= kstrtoul(ascii_value
, 16, &ulval
);
573 pr_debug("%s, 0x%lx, 0x%x\n", ascii_value
, ulval
, ret
);
576 value
= (s32
)lower_32_bits(ulval
);
581 req
= filp
->private_data
;
582 pm_qos_update_request(req
, value
);
588 static int __init
pm_qos_power_init(void)
593 BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array
) != PM_QOS_NUM_CLASSES
);
595 for (i
= PM_QOS_CPU_DMA_LATENCY
; i
< PM_QOS_NUM_CLASSES
; i
++) {
596 ret
= register_pm_qos_misc(pm_qos_array
[i
]);
598 printk(KERN_ERR
"pm_qos_param: %s setup failed\n",
599 pm_qos_array
[i
]->name
);
607 late_initcall(pm_qos_power_init
);