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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_params.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 | ||
44 | #include <linux/uaccess.h> | |
45 | ||
46 | /* | |
47 | * locking rule: all changes to requests or notifiers lists | |
48 | * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock | |
49 | * held, taken with _irqsave. One lock to rule them all | |
50 | */ | |
51 | enum pm_qos_type { | |
52 | PM_QOS_MAX, /* return the largest value */ | |
53 | PM_QOS_MIN /* return the smallest value */ | |
54 | }; | |
55 | ||
56 | struct pm_qos_object { | |
57 | struct plist_head requests; | |
58 | struct blocking_notifier_head *notifiers; | |
59 | struct miscdevice pm_qos_power_miscdev; | |
60 | char *name; | |
61 | s32 default_value; | |
62 | enum pm_qos_type type; | |
63 | }; | |
64 | ||
65 | static DEFINE_SPINLOCK(pm_qos_lock); | |
66 | ||
67 | static struct pm_qos_object null_pm_qos; | |
68 | static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier); | |
69 | static struct pm_qos_object cpu_dma_pm_qos = { | |
70 | .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock), | |
71 | .notifiers = &cpu_dma_lat_notifier, | |
72 | .name = "cpu_dma_latency", | |
73 | .default_value = 2000 * USEC_PER_SEC, | |
74 | .type = PM_QOS_MIN, | |
75 | }; | |
76 | ||
77 | static BLOCKING_NOTIFIER_HEAD(network_lat_notifier); | |
78 | static struct pm_qos_object network_lat_pm_qos = { | |
79 | .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock), | |
80 | .notifiers = &network_lat_notifier, | |
81 | .name = "network_latency", | |
82 | .default_value = 2000 * USEC_PER_SEC, | |
83 | .type = PM_QOS_MIN | |
84 | }; | |
85 | ||
86 | ||
87 | static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier); | |
88 | static struct pm_qos_object network_throughput_pm_qos = { | |
89 | .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock), | |
90 | .notifiers = &network_throughput_notifier, | |
91 | .name = "network_throughput", | |
92 | .default_value = 0, | |
93 | .type = PM_QOS_MAX, | |
94 | }; | |
95 | ||
96 | ||
97 | static struct pm_qos_object *pm_qos_array[] = { | |
98 | &null_pm_qos, | |
99 | &cpu_dma_pm_qos, | |
100 | &network_lat_pm_qos, | |
101 | &network_throughput_pm_qos | |
102 | }; | |
103 | ||
104 | static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, | |
105 | size_t count, loff_t *f_pos); | |
106 | static int pm_qos_power_open(struct inode *inode, struct file *filp); | |
107 | static int pm_qos_power_release(struct inode *inode, struct file *filp); | |
108 | ||
109 | static const struct file_operations pm_qos_power_fops = { | |
110 | .write = pm_qos_power_write, | |
111 | .open = pm_qos_power_open, | |
112 | .release = pm_qos_power_release, | |
113 | }; | |
114 | ||
115 | /* unlocked internal variant */ | |
116 | static inline int pm_qos_get_value(struct pm_qos_object *o) | |
117 | { | |
118 | if (plist_head_empty(&o->requests)) | |
119 | return o->default_value; | |
120 | ||
121 | switch (o->type) { | |
122 | case PM_QOS_MIN: | |
123 | return plist_last(&o->requests)->prio; | |
124 | ||
125 | case PM_QOS_MAX: | |
126 | return plist_first(&o->requests)->prio; | |
127 | ||
128 | default: | |
129 | /* runtime check for not using enum */ | |
130 | BUG(); | |
131 | } | |
132 | } | |
133 | ||
134 | static void update_target(struct pm_qos_object *o, struct plist_node *node, | |
135 | int del, int value) | |
136 | { | |
137 | unsigned long flags; | |
138 | int prev_value, curr_value; | |
139 | ||
140 | spin_lock_irqsave(&pm_qos_lock, flags); | |
141 | prev_value = pm_qos_get_value(o); | |
142 | /* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */ | |
143 | if (value != PM_QOS_DEFAULT_VALUE) { | |
144 | /* | |
145 | * to change the list, we atomically remove, reinit | |
146 | * with new value and add, then see if the extremal | |
147 | * changed | |
148 | */ | |
149 | plist_del(node, &o->requests); | |
150 | plist_node_init(node, value); | |
151 | plist_add(node, &o->requests); | |
152 | } else if (del) { | |
153 | plist_del(node, &o->requests); | |
154 | } else { | |
155 | plist_add(node, &o->requests); | |
156 | } | |
157 | curr_value = pm_qos_get_value(o); | |
158 | spin_unlock_irqrestore(&pm_qos_lock, flags); | |
159 | ||
160 | if (prev_value != curr_value) | |
161 | blocking_notifier_call_chain(o->notifiers, | |
162 | (unsigned long)curr_value, | |
163 | NULL); | |
164 | } | |
165 | ||
166 | static int register_pm_qos_misc(struct pm_qos_object *qos) | |
167 | { | |
168 | qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR; | |
169 | qos->pm_qos_power_miscdev.name = qos->name; | |
170 | qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops; | |
171 | ||
172 | return misc_register(&qos->pm_qos_power_miscdev); | |
173 | } | |
174 | ||
175 | static int find_pm_qos_object_by_minor(int minor) | |
176 | { | |
177 | int pm_qos_class; | |
178 | ||
179 | for (pm_qos_class = 0; | |
180 | pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) { | |
181 | if (minor == | |
182 | pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor) | |
183 | return pm_qos_class; | |
184 | } | |
185 | return -1; | |
186 | } | |
187 | ||
188 | /** | |
189 | * pm_qos_request - returns current system wide qos expectation | |
190 | * @pm_qos_class: identification of which qos value is requested | |
191 | * | |
192 | * This function returns the current target value in an atomic manner. | |
193 | */ | |
194 | int pm_qos_request(int pm_qos_class) | |
195 | { | |
196 | unsigned long flags; | |
197 | int value; | |
198 | ||
199 | spin_lock_irqsave(&pm_qos_lock, flags); | |
200 | value = pm_qos_get_value(pm_qos_array[pm_qos_class]); | |
201 | spin_unlock_irqrestore(&pm_qos_lock, flags); | |
202 | ||
203 | return value; | |
204 | } | |
205 | EXPORT_SYMBOL_GPL(pm_qos_request); | |
206 | ||
207 | int pm_qos_request_active(struct pm_qos_request_list *req) | |
208 | { | |
209 | return req->pm_qos_class != 0; | |
210 | } | |
211 | EXPORT_SYMBOL_GPL(pm_qos_request_active); | |
212 | ||
213 | /** | |
214 | * pm_qos_add_request - inserts new qos request into the list | |
215 | * @dep: pointer to a preallocated handle | |
216 | * @pm_qos_class: identifies which list of qos request to use | |
217 | * @value: defines the qos request | |
218 | * | |
219 | * This function inserts a new entry in the pm_qos_class list of requested qos | |
220 | * performance characteristics. It recomputes the aggregate QoS expectations | |
221 | * for the pm_qos_class of parameters and initializes the pm_qos_request_list | |
222 | * handle. Caller needs to save this handle for later use in updates and | |
223 | * removal. | |
224 | */ | |
225 | ||
226 | void pm_qos_add_request(struct pm_qos_request_list *dep, | |
227 | int pm_qos_class, s32 value) | |
228 | { | |
229 | struct pm_qos_object *o = pm_qos_array[pm_qos_class]; | |
230 | int new_value; | |
231 | ||
232 | if (pm_qos_request_active(dep)) { | |
233 | WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n"); | |
234 | return; | |
235 | } | |
236 | if (value == PM_QOS_DEFAULT_VALUE) | |
237 | new_value = o->default_value; | |
238 | else | |
239 | new_value = value; | |
240 | plist_node_init(&dep->list, new_value); | |
241 | dep->pm_qos_class = pm_qos_class; | |
242 | update_target(o, &dep->list, 0, PM_QOS_DEFAULT_VALUE); | |
243 | } | |
244 | EXPORT_SYMBOL_GPL(pm_qos_add_request); | |
245 | ||
246 | /** | |
247 | * pm_qos_update_request - modifies an existing qos request | |
248 | * @pm_qos_req : handle to list element holding a pm_qos request to use | |
249 | * @value: defines the qos request | |
250 | * | |
251 | * Updates an existing qos request for the pm_qos_class of parameters along | |
252 | * with updating the target pm_qos_class value. | |
253 | * | |
254 | * Attempts are made to make this code callable on hot code paths. | |
255 | */ | |
256 | void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req, | |
257 | s32 new_value) | |
258 | { | |
259 | s32 temp; | |
260 | struct pm_qos_object *o; | |
261 | ||
262 | if (!pm_qos_req) /*guard against callers passing in null */ | |
263 | return; | |
264 | ||
265 | if (!pm_qos_request_active(pm_qos_req)) { | |
266 | WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n"); | |
267 | return; | |
268 | } | |
269 | ||
270 | o = pm_qos_array[pm_qos_req->pm_qos_class]; | |
271 | ||
272 | if (new_value == PM_QOS_DEFAULT_VALUE) | |
273 | temp = o->default_value; | |
274 | else | |
275 | temp = new_value; | |
276 | ||
277 | if (temp != pm_qos_req->list.prio) | |
278 | update_target(o, &pm_qos_req->list, 0, temp); | |
279 | } | |
280 | EXPORT_SYMBOL_GPL(pm_qos_update_request); | |
281 | ||
282 | /** | |
283 | * pm_qos_remove_request - modifies an existing qos request | |
284 | * @pm_qos_req: handle to request list element | |
285 | * | |
286 | * Will remove pm qos request from the list of requests and | |
287 | * recompute the current target value for the pm_qos_class. Call this | |
288 | * on slow code paths. | |
289 | */ | |
290 | void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req) | |
291 | { | |
292 | struct pm_qos_object *o; | |
293 | ||
294 | if (pm_qos_req == NULL) | |
295 | return; | |
296 | /* silent return to keep pcm code cleaner */ | |
297 | ||
298 | if (!pm_qos_request_active(pm_qos_req)) { | |
299 | WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n"); | |
300 | return; | |
301 | } | |
302 | ||
303 | o = pm_qos_array[pm_qos_req->pm_qos_class]; | |
304 | update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE); | |
305 | memset(pm_qos_req, 0, sizeof(*pm_qos_req)); | |
306 | } | |
307 | EXPORT_SYMBOL_GPL(pm_qos_remove_request); | |
308 | ||
309 | /** | |
310 | * pm_qos_add_notifier - sets notification entry for changes to target value | |
311 | * @pm_qos_class: identifies which qos target changes should be notified. | |
312 | * @notifier: notifier block managed by caller. | |
313 | * | |
314 | * will register the notifier into a notification chain that gets called | |
315 | * upon changes to the pm_qos_class target value. | |
316 | */ | |
317 | int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier) | |
318 | { | |
319 | int retval; | |
320 | ||
321 | retval = blocking_notifier_chain_register( | |
322 | pm_qos_array[pm_qos_class]->notifiers, notifier); | |
323 | ||
324 | return retval; | |
325 | } | |
326 | EXPORT_SYMBOL_GPL(pm_qos_add_notifier); | |
327 | ||
328 | /** | |
329 | * pm_qos_remove_notifier - deletes notification entry from chain. | |
330 | * @pm_qos_class: identifies which qos target changes are notified. | |
331 | * @notifier: notifier block to be removed. | |
332 | * | |
333 | * will remove the notifier from the notification chain that gets called | |
334 | * upon changes to the pm_qos_class target value. | |
335 | */ | |
336 | int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier) | |
337 | { | |
338 | int retval; | |
339 | ||
340 | retval = blocking_notifier_chain_unregister( | |
341 | pm_qos_array[pm_qos_class]->notifiers, notifier); | |
342 | ||
343 | return retval; | |
344 | } | |
345 | EXPORT_SYMBOL_GPL(pm_qos_remove_notifier); | |
346 | ||
347 | static int pm_qos_power_open(struct inode *inode, struct file *filp) | |
348 | { | |
349 | long pm_qos_class; | |
350 | ||
351 | pm_qos_class = find_pm_qos_object_by_minor(iminor(inode)); | |
352 | if (pm_qos_class >= 0) { | |
353 | struct pm_qos_request_list *req = kzalloc(sizeof(*req), GFP_KERNEL); | |
354 | if (!req) | |
355 | return -ENOMEM; | |
356 | ||
357 | pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE); | |
358 | filp->private_data = req; | |
359 | ||
360 | if (filp->private_data) | |
361 | return 0; | |
362 | } | |
363 | return -EPERM; | |
364 | } | |
365 | ||
366 | static int pm_qos_power_release(struct inode *inode, struct file *filp) | |
367 | { | |
368 | struct pm_qos_request_list *req; | |
369 | ||
370 | req = filp->private_data; | |
371 | pm_qos_remove_request(req); | |
372 | kfree(req); | |
373 | ||
374 | return 0; | |
375 | } | |
376 | ||
377 | ||
378 | static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, | |
379 | size_t count, loff_t *f_pos) | |
380 | { | |
381 | s32 value; | |
382 | int x; | |
383 | char ascii_value[11]; | |
384 | struct pm_qos_request_list *pm_qos_req; | |
385 | ||
386 | if (count == sizeof(s32)) { | |
387 | if (copy_from_user(&value, buf, sizeof(s32))) | |
388 | return -EFAULT; | |
389 | } else if (count == 11) { /* len('0x12345678/0') */ | |
390 | if (copy_from_user(ascii_value, buf, 11)) | |
391 | return -EFAULT; | |
392 | if (strlen(ascii_value) != 10) | |
393 | return -EINVAL; | |
394 | x = sscanf(ascii_value, "%x", &value); | |
395 | if (x != 1) | |
396 | return -EINVAL; | |
397 | pr_debug("%s, %d, 0x%x\n", ascii_value, x, value); | |
398 | } else | |
399 | return -EINVAL; | |
400 | ||
401 | pm_qos_req = (struct pm_qos_request_list *)filp->private_data; | |
402 | pm_qos_update_request(pm_qos_req, value); | |
403 | ||
404 | return count; | |
405 | } | |
406 | ||
407 | ||
408 | static int __init pm_qos_power_init(void) | |
409 | { | |
410 | int ret = 0; | |
411 | ||
412 | ret = register_pm_qos_misc(&cpu_dma_pm_qos); | |
413 | if (ret < 0) { | |
414 | printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n"); | |
415 | return ret; | |
416 | } | |
417 | ret = register_pm_qos_misc(&network_lat_pm_qos); | |
418 | if (ret < 0) { | |
419 | printk(KERN_ERR "pm_qos_param: network_latency setup failed\n"); | |
420 | return ret; | |
421 | } | |
422 | ret = register_pm_qos_misc(&network_throughput_pm_qos); | |
423 | if (ret < 0) | |
424 | printk(KERN_ERR | |
425 | "pm_qos_param: network_throughput setup failed\n"); | |
426 | ||
427 | return ret; | |
428 | } | |
429 | ||
430 | late_initcall(pm_qos_power_init); |