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d82b3518 MG |
1 | /* |
2 | * This module exposes the interface to kernel space for specifying | |
3 | * QoS dependencies. It provides infrastructure for registration of: | |
4 | * | |
ed77134b | 5 | * Dependents on a QoS value : register requests |
d82b3518 MG |
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 | * | |
ed77134b | 17 | * There are lists of pm_qos_objects each one wrapping requests, notifiers |
d82b3518 | 18 | * |
ed77134b | 19 | * User mode requests on a QOS parameter register themselves to the |
d82b3518 MG |
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 | |
ed77134b MG |
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 | |
d82b3518 MG |
25 | * pointer or exits the pm_qos_object will get an opportunity to clean up. |
26 | * | |
bf1db69f | 27 | * Mark Gross <mgross@linux.intel.com> |
d82b3518 MG |
28 | */ |
29 | ||
ed77134b MG |
30 | /*#define DEBUG*/ |
31 | ||
d82b3518 MG |
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 | /* | |
ed77134b | 47 | * locking rule: all changes to requests or notifiers lists |
d82b3518 MG |
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 | */ | |
5f279845 JB |
51 | enum pm_qos_type { |
52 | PM_QOS_MAX, /* return the largest value */ | |
53 | PM_QOS_MIN /* return the smallest value */ | |
54 | }; | |
d82b3518 MG |
55 | |
56 | struct pm_qos_object { | |
5f279845 | 57 | struct plist_head requests; |
d82b3518 MG |
58 | struct blocking_notifier_head *notifiers; |
59 | struct miscdevice pm_qos_power_miscdev; | |
60 | char *name; | |
61 | s32 default_value; | |
5f279845 | 62 | enum pm_qos_type type; |
d82b3518 MG |
63 | }; |
64 | ||
5f279845 JB |
65 | static DEFINE_SPINLOCK(pm_qos_lock); |
66 | ||
d82b3518 MG |
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 = { | |
5f279845 | 70 | .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock), |
d82b3518 MG |
71 | .notifiers = &cpu_dma_lat_notifier, |
72 | .name = "cpu_dma_latency", | |
73 | .default_value = 2000 * USEC_PER_SEC, | |
5f279845 | 74 | .type = PM_QOS_MIN, |
d82b3518 MG |
75 | }; |
76 | ||
77 | static BLOCKING_NOTIFIER_HEAD(network_lat_notifier); | |
78 | static struct pm_qos_object network_lat_pm_qos = { | |
5f279845 | 79 | .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock), |
d82b3518 MG |
80 | .notifiers = &network_lat_notifier, |
81 | .name = "network_latency", | |
82 | .default_value = 2000 * USEC_PER_SEC, | |
5f279845 | 83 | .type = PM_QOS_MIN |
d82b3518 MG |
84 | }; |
85 | ||
86 | ||
87 | static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier); | |
88 | static struct pm_qos_object network_throughput_pm_qos = { | |
5f279845 | 89 | .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock), |
d82b3518 MG |
90 | .notifiers = &network_throughput_notifier, |
91 | .name = "network_throughput", | |
92 | .default_value = 0, | |
5f279845 | 93 | .type = PM_QOS_MAX, |
d82b3518 MG |
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 | ||
d82b3518 MG |
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 | ||
5f279845 JB |
115 | /* unlocked internal variant */ |
116 | static inline int pm_qos_get_value(struct pm_qos_object *o) | |
d82b3518 | 117 | { |
5f279845 JB |
118 | if (plist_head_empty(&o->requests)) |
119 | return o->default_value; | |
d82b3518 | 120 | |
5f279845 JB |
121 | switch (o->type) { |
122 | case PM_QOS_MIN: | |
123 | return plist_last(&o->requests)->prio; | |
d82b3518 | 124 | |
5f279845 JB |
125 | case PM_QOS_MAX: |
126 | return plist_first(&o->requests)->prio; | |
d82b3518 | 127 | |
5f279845 JB |
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) | |
d82b3518 | 136 | { |
d82b3518 | 137 | unsigned long flags; |
5f279845 | 138 | int prev_value, curr_value; |
d82b3518 MG |
139 | |
140 | spin_lock_irqsave(&pm_qos_lock, flags); | |
5f279845 JB |
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); | |
d82b3518 | 156 | } |
5f279845 | 157 | curr_value = pm_qos_get_value(o); |
d82b3518 MG |
158 | spin_unlock_irqrestore(&pm_qos_lock, flags); |
159 | ||
5f279845 JB |
160 | if (prev_value != curr_value) |
161 | blocking_notifier_call_chain(o->notifiers, | |
162 | (unsigned long)curr_value, | |
163 | NULL); | |
d82b3518 MG |
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 | /** | |
ed77134b | 189 | * pm_qos_request - returns current system wide qos expectation |
d82b3518 MG |
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 | */ | |
ed77134b | 194 | int pm_qos_request(int pm_qos_class) |
d82b3518 | 195 | { |
5f279845 JB |
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; | |
d82b3518 | 204 | } |
ed77134b | 205 | EXPORT_SYMBOL_GPL(pm_qos_request); |
d82b3518 | 206 | |
82f68251 JB |
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 | ||
d82b3518 | 213 | /** |
ed77134b | 214 | * pm_qos_add_request - inserts new qos request into the list |
d82b3518 | 215 | * @pm_qos_class: identifies which list of qos request to us |
d82b3518 MG |
216 | * @value: defines the qos request |
217 | * | |
218 | * This function inserts a new entry in the pm_qos_class list of requested qos | |
bf1db69f | 219 | * performance characteristics. It recomputes the aggregate QoS expectations |
ed77134b MG |
220 | * for the pm_qos_class of parameters, and returns the pm_qos_request list |
221 | * element as a handle for use in updating and removal. Call needs to save | |
222 | * this handle for later use. | |
d82b3518 | 223 | */ |
82f68251 JB |
224 | void pm_qos_add_request(struct pm_qos_request_list *dep, |
225 | int pm_qos_class, s32 value) | |
d82b3518 | 226 | { |
82f68251 JB |
227 | struct pm_qos_object *o = pm_qos_array[pm_qos_class]; |
228 | int new_value; | |
d82b3518 | 229 | |
82f68251 JB |
230 | if (pm_qos_request_active(dep)) { |
231 | WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n"); | |
232 | return; | |
233 | } | |
234 | if (value == PM_QOS_DEFAULT_VALUE) | |
235 | new_value = o->default_value; | |
236 | else | |
237 | new_value = value; | |
238 | plist_node_init(&dep->list, new_value); | |
239 | dep->pm_qos_class = pm_qos_class; | |
240 | update_target(o, &dep->list, 0, PM_QOS_DEFAULT_VALUE); | |
d82b3518 | 241 | } |
ed77134b | 242 | EXPORT_SYMBOL_GPL(pm_qos_add_request); |
d82b3518 MG |
243 | |
244 | /** | |
ed77134b MG |
245 | * pm_qos_update_request - modifies an existing qos request |
246 | * @pm_qos_req : handle to list element holding a pm_qos request to use | |
d82b3518 MG |
247 | * @value: defines the qos request |
248 | * | |
ed77134b | 249 | * Updates an existing qos request for the pm_qos_class of parameters along |
d82b3518 MG |
250 | * with updating the target pm_qos_class value. |
251 | * | |
ed77134b | 252 | * Attempts are made to make this code callable on hot code paths. |
d82b3518 | 253 | */ |
ed77134b | 254 | void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req, |
5f279845 | 255 | s32 new_value) |
d82b3518 | 256 | { |
ed77134b | 257 | s32 temp; |
5f279845 | 258 | struct pm_qos_object *o; |
d82b3518 | 259 | |
5f279845 JB |
260 | if (!pm_qos_req) /*guard against callers passing in null */ |
261 | return; | |
262 | ||
82f68251 JB |
263 | if (!pm_qos_request_active(pm_qos_req)) { |
264 | WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n"); | |
265 | return; | |
266 | } | |
267 | ||
5f279845 JB |
268 | o = pm_qos_array[pm_qos_req->pm_qos_class]; |
269 | ||
270 | if (new_value == PM_QOS_DEFAULT_VALUE) | |
271 | temp = o->default_value; | |
272 | else | |
273 | temp = new_value; | |
274 | ||
275 | if (temp != pm_qos_req->list.prio) | |
276 | update_target(o, &pm_qos_req->list, 0, temp); | |
d82b3518 | 277 | } |
ed77134b | 278 | EXPORT_SYMBOL_GPL(pm_qos_update_request); |
d82b3518 MG |
279 | |
280 | /** | |
ed77134b MG |
281 | * pm_qos_remove_request - modifies an existing qos request |
282 | * @pm_qos_req: handle to request list element | |
d82b3518 | 283 | * |
ed77134b MG |
284 | * Will remove pm qos request from the list of requests and |
285 | * recompute the current target value for the pm_qos_class. Call this | |
286 | * on slow code paths. | |
d82b3518 | 287 | */ |
ed77134b | 288 | void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req) |
d82b3518 | 289 | { |
5f279845 | 290 | struct pm_qos_object *o; |
ed77134b MG |
291 | |
292 | if (pm_qos_req == NULL) | |
293 | return; | |
294 | /* silent return to keep pcm code cleaner */ | |
d82b3518 | 295 | |
82f68251 JB |
296 | if (!pm_qos_request_active(pm_qos_req)) { |
297 | WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n"); | |
298 | return; | |
299 | } | |
300 | ||
5f279845 JB |
301 | o = pm_qos_array[pm_qos_req->pm_qos_class]; |
302 | update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE); | |
82f68251 | 303 | memset(pm_qos_req, 0, sizeof(*pm_qos_req)); |
d82b3518 | 304 | } |
ed77134b | 305 | EXPORT_SYMBOL_GPL(pm_qos_remove_request); |
d82b3518 MG |
306 | |
307 | /** | |
308 | * pm_qos_add_notifier - sets notification entry for changes to target value | |
309 | * @pm_qos_class: identifies which qos target changes should be notified. | |
310 | * @notifier: notifier block managed by caller. | |
311 | * | |
312 | * will register the notifier into a notification chain that gets called | |
bf1db69f | 313 | * upon changes to the pm_qos_class target value. |
d82b3518 | 314 | */ |
ed77134b | 315 | int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier) |
d82b3518 MG |
316 | { |
317 | int retval; | |
318 | ||
319 | retval = blocking_notifier_chain_register( | |
320 | pm_qos_array[pm_qos_class]->notifiers, notifier); | |
321 | ||
322 | return retval; | |
323 | } | |
324 | EXPORT_SYMBOL_GPL(pm_qos_add_notifier); | |
325 | ||
326 | /** | |
327 | * pm_qos_remove_notifier - deletes notification entry from chain. | |
328 | * @pm_qos_class: identifies which qos target changes are notified. | |
329 | * @notifier: notifier block to be removed. | |
330 | * | |
331 | * will remove the notifier from the notification chain that gets called | |
bf1db69f | 332 | * upon changes to the pm_qos_class target value. |
d82b3518 MG |
333 | */ |
334 | int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier) | |
335 | { | |
336 | int retval; | |
337 | ||
338 | retval = blocking_notifier_chain_unregister( | |
339 | pm_qos_array[pm_qos_class]->notifiers, notifier); | |
340 | ||
341 | return retval; | |
342 | } | |
343 | EXPORT_SYMBOL_GPL(pm_qos_remove_notifier); | |
344 | ||
d82b3518 MG |
345 | static int pm_qos_power_open(struct inode *inode, struct file *filp) |
346 | { | |
d82b3518 MG |
347 | long pm_qos_class; |
348 | ||
349 | pm_qos_class = find_pm_qos_object_by_minor(iminor(inode)); | |
350 | if (pm_qos_class >= 0) { | |
82f68251 JB |
351 | struct pm_qos_request_list *req = kzalloc(GFP_KERNEL, sizeof(*req)); |
352 | if (!req) | |
353 | return -ENOMEM; | |
354 | ||
355 | pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE); | |
356 | filp->private_data = req; | |
ed77134b MG |
357 | |
358 | if (filp->private_data) | |
d82b3518 MG |
359 | return 0; |
360 | } | |
d82b3518 MG |
361 | return -EPERM; |
362 | } | |
363 | ||
364 | static int pm_qos_power_release(struct inode *inode, struct file *filp) | |
365 | { | |
ed77134b | 366 | struct pm_qos_request_list *req; |
d82b3518 | 367 | |
82f68251 | 368 | req = filp->private_data; |
ed77134b | 369 | pm_qos_remove_request(req); |
82f68251 | 370 | kfree(req); |
d82b3518 MG |
371 | |
372 | return 0; | |
373 | } | |
374 | ||
ed77134b | 375 | |
d82b3518 MG |
376 | static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, |
377 | size_t count, loff_t *f_pos) | |
378 | { | |
379 | s32 value; | |
ed77134b MG |
380 | int x; |
381 | char ascii_value[11]; | |
382 | struct pm_qos_request_list *pm_qos_req; | |
383 | ||
384 | if (count == sizeof(s32)) { | |
385 | if (copy_from_user(&value, buf, sizeof(s32))) | |
386 | return -EFAULT; | |
387 | } else if (count == 11) { /* len('0x12345678/0') */ | |
388 | if (copy_from_user(ascii_value, buf, 11)) | |
389 | return -EFAULT; | |
390 | x = sscanf(ascii_value, "%x", &value); | |
391 | if (x != 1) | |
392 | return -EINVAL; | |
393 | pr_debug(KERN_ERR "%s, %d, 0x%x\n", ascii_value, x, value); | |
394 | } else | |
d82b3518 | 395 | return -EINVAL; |
d82b3518 | 396 | |
ed77134b MG |
397 | pm_qos_req = (struct pm_qos_request_list *)filp->private_data; |
398 | pm_qos_update_request(pm_qos_req, value); | |
399 | ||
400 | return count; | |
d82b3518 MG |
401 | } |
402 | ||
403 | ||
404 | static int __init pm_qos_power_init(void) | |
405 | { | |
406 | int ret = 0; | |
407 | ||
408 | ret = register_pm_qos_misc(&cpu_dma_pm_qos); | |
409 | if (ret < 0) { | |
410 | printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n"); | |
411 | return ret; | |
412 | } | |
413 | ret = register_pm_qos_misc(&network_lat_pm_qos); | |
414 | if (ret < 0) { | |
415 | printk(KERN_ERR "pm_qos_param: network_latency setup failed\n"); | |
416 | return ret; | |
417 | } | |
418 | ret = register_pm_qos_misc(&network_throughput_pm_qos); | |
419 | if (ret < 0) | |
420 | printk(KERN_ERR | |
421 | "pm_qos_param: network_throughput setup failed\n"); | |
422 | ||
423 | return ret; | |
424 | } | |
425 | ||
426 | late_initcall(pm_qos_power_init); |