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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 | * | |
5 | * Dependents on a QoS value : register requirements | |
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 requirements, notifiers | |
18 | * | |
19 | * User mode requirements 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 | * requirement is removed and a new qos target is computed. This way when the | |
24 | * requirement 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 | * | |
bf1db69f | 27 | * Mark Gross <mgross@linux.intel.com> |
d82b3518 MG |
28 | */ |
29 | ||
30 | #include <linux/pm_qos_params.h> | |
31 | #include <linux/sched.h> | |
db26e64d | 32 | #include <linux/smp_lock.h> |
d82b3518 MG |
33 | #include <linux/spinlock.h> |
34 | #include <linux/slab.h> | |
35 | #include <linux/time.h> | |
36 | #include <linux/fs.h> | |
37 | #include <linux/device.h> | |
38 | #include <linux/miscdevice.h> | |
39 | #include <linux/string.h> | |
40 | #include <linux/platform_device.h> | |
41 | #include <linux/init.h> | |
42 | ||
43 | #include <linux/uaccess.h> | |
44 | ||
45 | /* | |
46 | * locking rule: all changes to target_value or requirements or notifiers lists | |
47 | * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock | |
48 | * held, taken with _irqsave. One lock to rule them all | |
49 | */ | |
50 | struct requirement_list { | |
51 | struct list_head list; | |
52 | union { | |
53 | s32 value; | |
54 | s32 usec; | |
55 | s32 kbps; | |
56 | }; | |
57 | char *name; | |
58 | }; | |
59 | ||
60 | static s32 max_compare(s32 v1, s32 v2); | |
61 | static s32 min_compare(s32 v1, s32 v2); | |
62 | ||
63 | struct pm_qos_object { | |
64 | struct requirement_list requirements; | |
65 | struct blocking_notifier_head *notifiers; | |
66 | struct miscdevice pm_qos_power_miscdev; | |
67 | char *name; | |
68 | s32 default_value; | |
69 | s32 target_value; | |
70 | s32 (*comparitor)(s32, s32); | |
71 | }; | |
72 | ||
73 | static struct pm_qos_object null_pm_qos; | |
74 | static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier); | |
75 | static struct pm_qos_object cpu_dma_pm_qos = { | |
76 | .requirements = {LIST_HEAD_INIT(cpu_dma_pm_qos.requirements.list)}, | |
77 | .notifiers = &cpu_dma_lat_notifier, | |
78 | .name = "cpu_dma_latency", | |
79 | .default_value = 2000 * USEC_PER_SEC, | |
80 | .target_value = 2000 * USEC_PER_SEC, | |
81 | .comparitor = min_compare | |
82 | }; | |
83 | ||
84 | static BLOCKING_NOTIFIER_HEAD(network_lat_notifier); | |
85 | static struct pm_qos_object network_lat_pm_qos = { | |
86 | .requirements = {LIST_HEAD_INIT(network_lat_pm_qos.requirements.list)}, | |
87 | .notifiers = &network_lat_notifier, | |
88 | .name = "network_latency", | |
89 | .default_value = 2000 * USEC_PER_SEC, | |
90 | .target_value = 2000 * USEC_PER_SEC, | |
91 | .comparitor = min_compare | |
92 | }; | |
93 | ||
94 | ||
95 | static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier); | |
96 | static struct pm_qos_object network_throughput_pm_qos = { | |
97 | .requirements = | |
98 | {LIST_HEAD_INIT(network_throughput_pm_qos.requirements.list)}, | |
99 | .notifiers = &network_throughput_notifier, | |
100 | .name = "network_throughput", | |
101 | .default_value = 0, | |
102 | .target_value = 0, | |
103 | .comparitor = max_compare | |
104 | }; | |
105 | ||
106 | ||
107 | static struct pm_qos_object *pm_qos_array[] = { | |
108 | &null_pm_qos, | |
109 | &cpu_dma_pm_qos, | |
110 | &network_lat_pm_qos, | |
111 | &network_throughput_pm_qos | |
112 | }; | |
113 | ||
114 | static DEFINE_SPINLOCK(pm_qos_lock); | |
115 | ||
116 | static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, | |
117 | size_t count, loff_t *f_pos); | |
118 | static int pm_qos_power_open(struct inode *inode, struct file *filp); | |
119 | static int pm_qos_power_release(struct inode *inode, struct file *filp); | |
120 | ||
121 | static const struct file_operations pm_qos_power_fops = { | |
122 | .write = pm_qos_power_write, | |
123 | .open = pm_qos_power_open, | |
124 | .release = pm_qos_power_release, | |
125 | }; | |
126 | ||
127 | /* static helper functions */ | |
128 | static s32 max_compare(s32 v1, s32 v2) | |
129 | { | |
130 | return max(v1, v2); | |
131 | } | |
132 | ||
133 | static s32 min_compare(s32 v1, s32 v2) | |
134 | { | |
135 | return min(v1, v2); | |
136 | } | |
137 | ||
138 | ||
139 | static void update_target(int target) | |
140 | { | |
141 | s32 extreme_value; | |
142 | struct requirement_list *node; | |
143 | unsigned long flags; | |
144 | int call_notifier = 0; | |
145 | ||
146 | spin_lock_irqsave(&pm_qos_lock, flags); | |
147 | extreme_value = pm_qos_array[target]->default_value; | |
148 | list_for_each_entry(node, | |
149 | &pm_qos_array[target]->requirements.list, list) { | |
150 | extreme_value = pm_qos_array[target]->comparitor( | |
151 | extreme_value, node->value); | |
152 | } | |
153 | if (pm_qos_array[target]->target_value != extreme_value) { | |
154 | call_notifier = 1; | |
155 | pm_qos_array[target]->target_value = extreme_value; | |
156 | pr_debug(KERN_ERR "new target for qos %d is %d\n", target, | |
157 | pm_qos_array[target]->target_value); | |
158 | } | |
159 | spin_unlock_irqrestore(&pm_qos_lock, flags); | |
160 | ||
161 | if (call_notifier) | |
162 | blocking_notifier_call_chain(pm_qos_array[target]->notifiers, | |
163 | (unsigned long) extreme_value, 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_requirement - 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_requirement(int pm_qos_class) | |
195 | { | |
196 | int ret_val; | |
197 | unsigned long flags; | |
198 | ||
199 | spin_lock_irqsave(&pm_qos_lock, flags); | |
200 | ret_val = pm_qos_array[pm_qos_class]->target_value; | |
201 | spin_unlock_irqrestore(&pm_qos_lock, flags); | |
202 | ||
203 | return ret_val; | |
204 | } | |
205 | EXPORT_SYMBOL_GPL(pm_qos_requirement); | |
206 | ||
207 | /** | |
208 | * pm_qos_add_requirement - inserts new qos request into the list | |
209 | * @pm_qos_class: identifies which list of qos request to us | |
210 | * @name: identifies the request | |
211 | * @value: defines the qos request | |
212 | * | |
213 | * This function inserts a new entry in the pm_qos_class list of requested qos | |
bf1db69f RH |
214 | * performance characteristics. It recomputes the aggregate QoS expectations |
215 | * for the pm_qos_class of parameters. | |
d82b3518 MG |
216 | */ |
217 | int pm_qos_add_requirement(int pm_qos_class, char *name, s32 value) | |
218 | { | |
219 | struct requirement_list *dep; | |
220 | unsigned long flags; | |
221 | ||
222 | dep = kzalloc(sizeof(struct requirement_list), GFP_KERNEL); | |
223 | if (dep) { | |
224 | if (value == PM_QOS_DEFAULT_VALUE) | |
225 | dep->value = pm_qos_array[pm_qos_class]->default_value; | |
226 | else | |
227 | dep->value = value; | |
228 | dep->name = kstrdup(name, GFP_KERNEL); | |
229 | if (!dep->name) | |
230 | goto cleanup; | |
231 | ||
232 | spin_lock_irqsave(&pm_qos_lock, flags); | |
233 | list_add(&dep->list, | |
234 | &pm_qos_array[pm_qos_class]->requirements.list); | |
235 | spin_unlock_irqrestore(&pm_qos_lock, flags); | |
236 | update_target(pm_qos_class); | |
237 | ||
238 | return 0; | |
239 | } | |
240 | ||
241 | cleanup: | |
242 | kfree(dep); | |
243 | return -ENOMEM; | |
244 | } | |
245 | EXPORT_SYMBOL_GPL(pm_qos_add_requirement); | |
246 | ||
247 | /** | |
248 | * pm_qos_update_requirement - modifies an existing qos request | |
249 | * @pm_qos_class: identifies which list of qos request to us | |
250 | * @name: identifies the request | |
251 | * @value: defines the qos request | |
252 | * | |
bf1db69f | 253 | * Updates an existing qos requirement for the pm_qos_class of parameters along |
d82b3518 MG |
254 | * with updating the target pm_qos_class value. |
255 | * | |
bf1db69f | 256 | * If the named request isn't in the list then no change is made. |
d82b3518 MG |
257 | */ |
258 | int pm_qos_update_requirement(int pm_qos_class, char *name, s32 new_value) | |
259 | { | |
260 | unsigned long flags; | |
261 | struct requirement_list *node; | |
262 | int pending_update = 0; | |
263 | ||
264 | spin_lock_irqsave(&pm_qos_lock, flags); | |
265 | list_for_each_entry(node, | |
266 | &pm_qos_array[pm_qos_class]->requirements.list, list) { | |
267 | if (strcmp(node->name, name) == 0) { | |
268 | if (new_value == PM_QOS_DEFAULT_VALUE) | |
269 | node->value = | |
270 | pm_qos_array[pm_qos_class]->default_value; | |
271 | else | |
272 | node->value = new_value; | |
273 | pending_update = 1; | |
274 | break; | |
275 | } | |
276 | } | |
277 | spin_unlock_irqrestore(&pm_qos_lock, flags); | |
278 | if (pending_update) | |
279 | update_target(pm_qos_class); | |
280 | ||
281 | return 0; | |
282 | } | |
283 | EXPORT_SYMBOL_GPL(pm_qos_update_requirement); | |
284 | ||
285 | /** | |
286 | * pm_qos_remove_requirement - modifies an existing qos request | |
287 | * @pm_qos_class: identifies which list of qos request to us | |
288 | * @name: identifies the request | |
289 | * | |
bf1db69f | 290 | * Will remove named qos request from pm_qos_class list of parameters and |
d82b3518 MG |
291 | * recompute the current target value for the pm_qos_class. |
292 | */ | |
293 | void pm_qos_remove_requirement(int pm_qos_class, char *name) | |
294 | { | |
295 | unsigned long flags; | |
296 | struct requirement_list *node; | |
297 | int pending_update = 0; | |
298 | ||
299 | spin_lock_irqsave(&pm_qos_lock, flags); | |
300 | list_for_each_entry(node, | |
301 | &pm_qos_array[pm_qos_class]->requirements.list, list) { | |
302 | if (strcmp(node->name, name) == 0) { | |
303 | kfree(node->name); | |
304 | list_del(&node->list); | |
305 | kfree(node); | |
306 | pending_update = 1; | |
307 | break; | |
308 | } | |
309 | } | |
310 | spin_unlock_irqrestore(&pm_qos_lock, flags); | |
311 | if (pending_update) | |
312 | update_target(pm_qos_class); | |
313 | } | |
314 | EXPORT_SYMBOL_GPL(pm_qos_remove_requirement); | |
315 | ||
316 | /** | |
317 | * pm_qos_add_notifier - sets notification entry for changes to target value | |
318 | * @pm_qos_class: identifies which qos target changes should be notified. | |
319 | * @notifier: notifier block managed by caller. | |
320 | * | |
321 | * will register the notifier into a notification chain that gets called | |
bf1db69f | 322 | * upon changes to the pm_qos_class target value. |
d82b3518 MG |
323 | */ |
324 | int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier) | |
325 | { | |
326 | int retval; | |
327 | ||
328 | retval = blocking_notifier_chain_register( | |
329 | pm_qos_array[pm_qos_class]->notifiers, notifier); | |
330 | ||
331 | return retval; | |
332 | } | |
333 | EXPORT_SYMBOL_GPL(pm_qos_add_notifier); | |
334 | ||
335 | /** | |
336 | * pm_qos_remove_notifier - deletes notification entry from chain. | |
337 | * @pm_qos_class: identifies which qos target changes are notified. | |
338 | * @notifier: notifier block to be removed. | |
339 | * | |
340 | * will remove the notifier from the notification chain that gets called | |
bf1db69f | 341 | * upon changes to the pm_qos_class target value. |
d82b3518 MG |
342 | */ |
343 | int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier) | |
344 | { | |
345 | int retval; | |
346 | ||
347 | retval = blocking_notifier_chain_unregister( | |
348 | pm_qos_array[pm_qos_class]->notifiers, notifier); | |
349 | ||
350 | return retval; | |
351 | } | |
352 | EXPORT_SYMBOL_GPL(pm_qos_remove_notifier); | |
353 | ||
354 | #define PID_NAME_LEN sizeof("process_1234567890") | |
355 | static char name[PID_NAME_LEN]; | |
356 | ||
357 | static int pm_qos_power_open(struct inode *inode, struct file *filp) | |
358 | { | |
359 | int ret; | |
360 | long pm_qos_class; | |
361 | ||
db26e64d | 362 | lock_kernel(); |
d82b3518 MG |
363 | pm_qos_class = find_pm_qos_object_by_minor(iminor(inode)); |
364 | if (pm_qos_class >= 0) { | |
365 | filp->private_data = (void *)pm_qos_class; | |
366 | sprintf(name, "process_%d", current->pid); | |
367 | ret = pm_qos_add_requirement(pm_qos_class, name, | |
368 | PM_QOS_DEFAULT_VALUE); | |
db26e64d AB |
369 | if (ret >= 0) { |
370 | unlock_kernel(); | |
d82b3518 | 371 | return 0; |
db26e64d | 372 | } |
d82b3518 | 373 | } |
db26e64d | 374 | unlock_kernel(); |
d82b3518 MG |
375 | |
376 | return -EPERM; | |
377 | } | |
378 | ||
379 | static int pm_qos_power_release(struct inode *inode, struct file *filp) | |
380 | { | |
381 | int pm_qos_class; | |
382 | ||
383 | pm_qos_class = (long)filp->private_data; | |
384 | sprintf(name, "process_%d", current->pid); | |
385 | pm_qos_remove_requirement(pm_qos_class, name); | |
386 | ||
387 | return 0; | |
388 | } | |
389 | ||
390 | static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf, | |
391 | size_t count, loff_t *f_pos) | |
392 | { | |
393 | s32 value; | |
394 | int pm_qos_class; | |
395 | ||
396 | pm_qos_class = (long)filp->private_data; | |
397 | if (count != sizeof(s32)) | |
398 | return -EINVAL; | |
399 | if (copy_from_user(&value, buf, sizeof(s32))) | |
400 | return -EFAULT; | |
401 | sprintf(name, "process_%d", current->pid); | |
402 | pm_qos_update_requirement(pm_qos_class, name, value); | |
403 | ||
404 | return sizeof(s32); | |
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); |