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e1f60b29 NM |
1 | /* |
2 | * Generic OPP Interface | |
3 | * | |
4 | * Copyright (C) 2009-2010 Texas Instruments Incorporated. | |
5 | * Nishanth Menon | |
6 | * Romit Dasgupta | |
7 | * Kevin Hilman | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License version 2 as | |
11 | * published by the Free Software Foundation. | |
12 | */ | |
13 | ||
14 | #include <linux/kernel.h> | |
15 | #include <linux/errno.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/init.h> | |
18 | #include <linux/slab.h> | |
19 | #include <linux/cpufreq.h> | |
20 | #include <linux/list.h> | |
21 | #include <linux/rculist.h> | |
22 | #include <linux/rcupdate.h> | |
23 | #include <linux/opp.h> | |
24 | ||
25 | /* | |
26 | * Internal data structure organization with the OPP layer library is as | |
27 | * follows: | |
28 | * dev_opp_list (root) | |
29 | * |- device 1 (represents voltage domain 1) | |
30 | * | |- opp 1 (availability, freq, voltage) | |
31 | * | |- opp 2 .. | |
32 | * ... ... | |
33 | * | `- opp n .. | |
34 | * |- device 2 (represents the next voltage domain) | |
35 | * ... | |
36 | * `- device m (represents mth voltage domain) | |
37 | * device 1, 2.. are represented by dev_opp structure while each opp | |
38 | * is represented by the opp structure. | |
39 | */ | |
40 | ||
41 | /** | |
42 | * struct opp - Generic OPP description structure | |
43 | * @node: opp list node. The nodes are maintained throughout the lifetime | |
44 | * of boot. It is expected only an optimal set of OPPs are | |
45 | * added to the library by the SoC framework. | |
46 | * RCU usage: opp list is traversed with RCU locks. node | |
47 | * modification is possible realtime, hence the modifications | |
48 | * are protected by the dev_opp_list_lock for integrity. | |
49 | * IMPORTANT: the opp nodes should be maintained in increasing | |
50 | * order. | |
51 | * @available: true/false - marks if this OPP as available or not | |
52 | * @rate: Frequency in hertz | |
53 | * @u_volt: Nominal voltage in microvolts corresponding to this OPP | |
54 | * @dev_opp: points back to the device_opp struct this opp belongs to | |
55 | * | |
56 | * This structure stores the OPP information for a given device. | |
57 | */ | |
58 | struct opp { | |
59 | struct list_head node; | |
60 | ||
61 | bool available; | |
62 | unsigned long rate; | |
63 | unsigned long u_volt; | |
64 | ||
65 | struct device_opp *dev_opp; | |
66 | }; | |
67 | ||
68 | /** | |
69 | * struct device_opp - Device opp structure | |
70 | * @node: list node - contains the devices with OPPs that | |
71 | * have been registered. Nodes once added are not modified in this | |
72 | * list. | |
73 | * RCU usage: nodes are not modified in the list of device_opp, | |
74 | * however addition is possible and is secured by dev_opp_list_lock | |
75 | * @dev: device pointer | |
03ca370f | 76 | * @head: notifier head to notify the OPP availability changes. |
e1f60b29 NM |
77 | * @opp_list: list of opps |
78 | * | |
79 | * This is an internal data structure maintaining the link to opps attached to | |
80 | * a device. This structure is not meant to be shared to users as it is | |
81 | * meant for book keeping and private to OPP library | |
82 | */ | |
83 | struct device_opp { | |
84 | struct list_head node; | |
85 | ||
86 | struct device *dev; | |
03ca370f | 87 | struct srcu_notifier_head head; |
e1f60b29 NM |
88 | struct list_head opp_list; |
89 | }; | |
90 | ||
91 | /* | |
92 | * The root of the list of all devices. All device_opp structures branch off | |
93 | * from here, with each device_opp containing the list of opp it supports in | |
94 | * various states of availability. | |
95 | */ | |
96 | static LIST_HEAD(dev_opp_list); | |
97 | /* Lock to allow exclusive modification to the device and opp lists */ | |
98 | static DEFINE_MUTEX(dev_opp_list_lock); | |
99 | ||
100 | /** | |
101 | * find_device_opp() - find device_opp struct using device pointer | |
102 | * @dev: device pointer used to lookup device OPPs | |
103 | * | |
104 | * Search list of device OPPs for one containing matching device. Does a RCU | |
105 | * reader operation to grab the pointer needed. | |
106 | * | |
107 | * Returns pointer to 'struct device_opp' if found, otherwise -ENODEV or | |
108 | * -EINVAL based on type of error. | |
109 | * | |
110 | * Locking: This function must be called under rcu_read_lock(). device_opp | |
111 | * is a RCU protected pointer. This means that device_opp is valid as long | |
112 | * as we are under RCU lock. | |
113 | */ | |
114 | static struct device_opp *find_device_opp(struct device *dev) | |
115 | { | |
116 | struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV); | |
117 | ||
118 | if (unlikely(IS_ERR_OR_NULL(dev))) { | |
119 | pr_err("%s: Invalid parameters\n", __func__); | |
120 | return ERR_PTR(-EINVAL); | |
121 | } | |
122 | ||
123 | list_for_each_entry_rcu(tmp_dev_opp, &dev_opp_list, node) { | |
124 | if (tmp_dev_opp->dev == dev) { | |
125 | dev_opp = tmp_dev_opp; | |
126 | break; | |
127 | } | |
128 | } | |
129 | ||
130 | return dev_opp; | |
131 | } | |
132 | ||
133 | /** | |
134 | * opp_get_voltage() - Gets the voltage corresponding to an available opp | |
135 | * @opp: opp for which voltage has to be returned for | |
136 | * | |
137 | * Return voltage in micro volt corresponding to the opp, else | |
138 | * return 0 | |
139 | * | |
140 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu | |
141 | * protected pointer. This means that opp which could have been fetched by | |
142 | * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are | |
143 | * under RCU lock. The pointer returned by the opp_find_freq family must be | |
144 | * used in the same section as the usage of this function with the pointer | |
145 | * prior to unlocking with rcu_read_unlock() to maintain the integrity of the | |
146 | * pointer. | |
147 | */ | |
148 | unsigned long opp_get_voltage(struct opp *opp) | |
149 | { | |
150 | struct opp *tmp_opp; | |
151 | unsigned long v = 0; | |
152 | ||
153 | tmp_opp = rcu_dereference(opp); | |
154 | if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available) | |
155 | pr_err("%s: Invalid parameters\n", __func__); | |
156 | else | |
157 | v = tmp_opp->u_volt; | |
158 | ||
159 | return v; | |
160 | } | |
161 | ||
162 | /** | |
163 | * opp_get_freq() - Gets the frequency corresponding to an available opp | |
164 | * @opp: opp for which frequency has to be returned for | |
165 | * | |
166 | * Return frequency in hertz corresponding to the opp, else | |
167 | * return 0 | |
168 | * | |
169 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu | |
170 | * protected pointer. This means that opp which could have been fetched by | |
171 | * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are | |
172 | * under RCU lock. The pointer returned by the opp_find_freq family must be | |
173 | * used in the same section as the usage of this function with the pointer | |
174 | * prior to unlocking with rcu_read_unlock() to maintain the integrity of the | |
175 | * pointer. | |
176 | */ | |
177 | unsigned long opp_get_freq(struct opp *opp) | |
178 | { | |
179 | struct opp *tmp_opp; | |
180 | unsigned long f = 0; | |
181 | ||
182 | tmp_opp = rcu_dereference(opp); | |
183 | if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available) | |
184 | pr_err("%s: Invalid parameters\n", __func__); | |
185 | else | |
186 | f = tmp_opp->rate; | |
187 | ||
188 | return f; | |
189 | } | |
190 | ||
191 | /** | |
192 | * opp_get_opp_count() - Get number of opps available in the opp list | |
193 | * @dev: device for which we do this operation | |
194 | * | |
195 | * This function returns the number of available opps if there are any, | |
196 | * else returns 0 if none or the corresponding error value. | |
197 | * | |
198 | * Locking: This function must be called under rcu_read_lock(). This function | |
199 | * internally references two RCU protected structures: device_opp and opp which | |
200 | * are safe as long as we are under a common RCU locked section. | |
201 | */ | |
202 | int opp_get_opp_count(struct device *dev) | |
203 | { | |
204 | struct device_opp *dev_opp; | |
205 | struct opp *temp_opp; | |
206 | int count = 0; | |
207 | ||
208 | dev_opp = find_device_opp(dev); | |
209 | if (IS_ERR(dev_opp)) { | |
210 | int r = PTR_ERR(dev_opp); | |
211 | dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r); | |
212 | return r; | |
213 | } | |
214 | ||
215 | list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { | |
216 | if (temp_opp->available) | |
217 | count++; | |
218 | } | |
219 | ||
220 | return count; | |
221 | } | |
222 | ||
223 | /** | |
224 | * opp_find_freq_exact() - search for an exact frequency | |
225 | * @dev: device for which we do this operation | |
226 | * @freq: frequency to search for | |
7ae49618 | 227 | * @available: true/false - match for available opp |
e1f60b29 NM |
228 | * |
229 | * Searches for exact match in the opp list and returns pointer to the matching | |
230 | * opp if found, else returns ERR_PTR in case of error and should be handled | |
231 | * using IS_ERR. | |
232 | * | |
233 | * Note: available is a modifier for the search. if available=true, then the | |
234 | * match is for exact matching frequency and is available in the stored OPP | |
235 | * table. if false, the match is for exact frequency which is not available. | |
236 | * | |
237 | * This provides a mechanism to enable an opp which is not available currently | |
238 | * or the opposite as well. | |
239 | * | |
240 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu | |
241 | * protected pointer. The reason for the same is that the opp pointer which is | |
242 | * returned will remain valid for use with opp_get_{voltage, freq} only while | |
243 | * under the locked area. The pointer returned must be used prior to unlocking | |
244 | * with rcu_read_unlock() to maintain the integrity of the pointer. | |
245 | */ | |
246 | struct opp *opp_find_freq_exact(struct device *dev, unsigned long freq, | |
247 | bool available) | |
248 | { | |
249 | struct device_opp *dev_opp; | |
250 | struct opp *temp_opp, *opp = ERR_PTR(-ENODEV); | |
251 | ||
252 | dev_opp = find_device_opp(dev); | |
253 | if (IS_ERR(dev_opp)) { | |
254 | int r = PTR_ERR(dev_opp); | |
255 | dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r); | |
256 | return ERR_PTR(r); | |
257 | } | |
258 | ||
259 | list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { | |
260 | if (temp_opp->available == available && | |
261 | temp_opp->rate == freq) { | |
262 | opp = temp_opp; | |
263 | break; | |
264 | } | |
265 | } | |
266 | ||
267 | return opp; | |
268 | } | |
269 | ||
270 | /** | |
271 | * opp_find_freq_ceil() - Search for an rounded ceil freq | |
272 | * @dev: device for which we do this operation | |
273 | * @freq: Start frequency | |
274 | * | |
275 | * Search for the matching ceil *available* OPP from a starting freq | |
276 | * for a device. | |
277 | * | |
278 | * Returns matching *opp and refreshes *freq accordingly, else returns | |
279 | * ERR_PTR in case of error and should be handled using IS_ERR. | |
280 | * | |
281 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu | |
282 | * protected pointer. The reason for the same is that the opp pointer which is | |
283 | * returned will remain valid for use with opp_get_{voltage, freq} only while | |
284 | * under the locked area. The pointer returned must be used prior to unlocking | |
285 | * with rcu_read_unlock() to maintain the integrity of the pointer. | |
286 | */ | |
287 | struct opp *opp_find_freq_ceil(struct device *dev, unsigned long *freq) | |
288 | { | |
289 | struct device_opp *dev_opp; | |
290 | struct opp *temp_opp, *opp = ERR_PTR(-ENODEV); | |
291 | ||
292 | if (!dev || !freq) { | |
293 | dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq); | |
294 | return ERR_PTR(-EINVAL); | |
295 | } | |
296 | ||
297 | dev_opp = find_device_opp(dev); | |
298 | if (IS_ERR(dev_opp)) | |
299 | return opp; | |
300 | ||
301 | list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { | |
302 | if (temp_opp->available && temp_opp->rate >= *freq) { | |
303 | opp = temp_opp; | |
304 | *freq = opp->rate; | |
305 | break; | |
306 | } | |
307 | } | |
308 | ||
309 | return opp; | |
310 | } | |
311 | ||
312 | /** | |
313 | * opp_find_freq_floor() - Search for a rounded floor freq | |
314 | * @dev: device for which we do this operation | |
315 | * @freq: Start frequency | |
316 | * | |
317 | * Search for the matching floor *available* OPP from a starting freq | |
318 | * for a device. | |
319 | * | |
320 | * Returns matching *opp and refreshes *freq accordingly, else returns | |
321 | * ERR_PTR in case of error and should be handled using IS_ERR. | |
322 | * | |
323 | * Locking: This function must be called under rcu_read_lock(). opp is a rcu | |
324 | * protected pointer. The reason for the same is that the opp pointer which is | |
325 | * returned will remain valid for use with opp_get_{voltage, freq} only while | |
326 | * under the locked area. The pointer returned must be used prior to unlocking | |
327 | * with rcu_read_unlock() to maintain the integrity of the pointer. | |
328 | */ | |
329 | struct opp *opp_find_freq_floor(struct device *dev, unsigned long *freq) | |
330 | { | |
331 | struct device_opp *dev_opp; | |
332 | struct opp *temp_opp, *opp = ERR_PTR(-ENODEV); | |
333 | ||
334 | if (!dev || !freq) { | |
335 | dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq); | |
336 | return ERR_PTR(-EINVAL); | |
337 | } | |
338 | ||
339 | dev_opp = find_device_opp(dev); | |
340 | if (IS_ERR(dev_opp)) | |
341 | return opp; | |
342 | ||
343 | list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { | |
344 | if (temp_opp->available) { | |
345 | /* go to the next node, before choosing prev */ | |
346 | if (temp_opp->rate > *freq) | |
347 | break; | |
348 | else | |
349 | opp = temp_opp; | |
350 | } | |
351 | } | |
352 | if (!IS_ERR(opp)) | |
353 | *freq = opp->rate; | |
354 | ||
355 | return opp; | |
356 | } | |
357 | ||
358 | /** | |
359 | * opp_add() - Add an OPP table from a table definitions | |
360 | * @dev: device for which we do this operation | |
361 | * @freq: Frequency in Hz for this OPP | |
362 | * @u_volt: Voltage in uVolts for this OPP | |
363 | * | |
364 | * This function adds an opp definition to the opp list and returns status. | |
365 | * The opp is made available by default and it can be controlled using | |
366 | * opp_enable/disable functions. | |
367 | * | |
368 | * Locking: The internal device_opp and opp structures are RCU protected. | |
369 | * Hence this function internally uses RCU updater strategy with mutex locks | |
370 | * to keep the integrity of the internal data structures. Callers should ensure | |
371 | * that this function is *NOT* called under RCU protection or in contexts where | |
372 | * mutex cannot be locked. | |
373 | */ | |
374 | int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) | |
375 | { | |
376 | struct device_opp *dev_opp = NULL; | |
377 | struct opp *opp, *new_opp; | |
378 | struct list_head *head; | |
379 | ||
380 | /* allocate new OPP node */ | |
381 | new_opp = kzalloc(sizeof(struct opp), GFP_KERNEL); | |
382 | if (!new_opp) { | |
383 | dev_warn(dev, "%s: Unable to create new OPP node\n", __func__); | |
384 | return -ENOMEM; | |
385 | } | |
386 | ||
387 | /* Hold our list modification lock here */ | |
388 | mutex_lock(&dev_opp_list_lock); | |
389 | ||
390 | /* Check for existing list for 'dev' */ | |
391 | dev_opp = find_device_opp(dev); | |
392 | if (IS_ERR(dev_opp)) { | |
393 | /* | |
394 | * Allocate a new device OPP table. In the infrequent case | |
395 | * where a new device is needed to be added, we pay this | |
396 | * penalty. | |
397 | */ | |
398 | dev_opp = kzalloc(sizeof(struct device_opp), GFP_KERNEL); | |
399 | if (!dev_opp) { | |
400 | mutex_unlock(&dev_opp_list_lock); | |
401 | kfree(new_opp); | |
402 | dev_warn(dev, | |
403 | "%s: Unable to create device OPP structure\n", | |
404 | __func__); | |
405 | return -ENOMEM; | |
406 | } | |
407 | ||
408 | dev_opp->dev = dev; | |
03ca370f | 409 | srcu_init_notifier_head(&dev_opp->head); |
e1f60b29 NM |
410 | INIT_LIST_HEAD(&dev_opp->opp_list); |
411 | ||
412 | /* Secure the device list modification */ | |
413 | list_add_rcu(&dev_opp->node, &dev_opp_list); | |
414 | } | |
415 | ||
416 | /* populate the opp table */ | |
417 | new_opp->dev_opp = dev_opp; | |
418 | new_opp->rate = freq; | |
419 | new_opp->u_volt = u_volt; | |
420 | new_opp->available = true; | |
421 | ||
422 | /* Insert new OPP in order of increasing frequency */ | |
423 | head = &dev_opp->opp_list; | |
424 | list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) { | |
425 | if (new_opp->rate < opp->rate) | |
426 | break; | |
427 | else | |
428 | head = &opp->node; | |
429 | } | |
430 | ||
431 | list_add_rcu(&new_opp->node, head); | |
432 | mutex_unlock(&dev_opp_list_lock); | |
433 | ||
03ca370f MH |
434 | /* |
435 | * Notify the changes in the availability of the operable | |
436 | * frequency/voltage list. | |
437 | */ | |
438 | srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ADD, new_opp); | |
e1f60b29 NM |
439 | return 0; |
440 | } | |
441 | ||
442 | /** | |
443 | * opp_set_availability() - helper to set the availability of an opp | |
444 | * @dev: device for which we do this operation | |
445 | * @freq: OPP frequency to modify availability | |
446 | * @availability_req: availability status requested for this opp | |
447 | * | |
448 | * Set the availability of an OPP with an RCU operation, opp_{enable,disable} | |
449 | * share a common logic which is isolated here. | |
450 | * | |
451 | * Returns -EINVAL for bad pointers, -ENOMEM if no memory available for the | |
452 | * copy operation, returns 0 if no modifcation was done OR modification was | |
453 | * successful. | |
454 | * | |
455 | * Locking: The internal device_opp and opp structures are RCU protected. | |
456 | * Hence this function internally uses RCU updater strategy with mutex locks to | |
457 | * keep the integrity of the internal data structures. Callers should ensure | |
458 | * that this function is *NOT* called under RCU protection or in contexts where | |
459 | * mutex locking or synchronize_rcu() blocking calls cannot be used. | |
460 | */ | |
461 | static int opp_set_availability(struct device *dev, unsigned long freq, | |
462 | bool availability_req) | |
463 | { | |
fc92805a | 464 | struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV); |
e1f60b29 NM |
465 | struct opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV); |
466 | int r = 0; | |
467 | ||
468 | /* keep the node allocated */ | |
469 | new_opp = kmalloc(sizeof(struct opp), GFP_KERNEL); | |
470 | if (!new_opp) { | |
471 | dev_warn(dev, "%s: Unable to create OPP\n", __func__); | |
472 | return -ENOMEM; | |
473 | } | |
474 | ||
475 | mutex_lock(&dev_opp_list_lock); | |
476 | ||
477 | /* Find the device_opp */ | |
478 | list_for_each_entry(tmp_dev_opp, &dev_opp_list, node) { | |
479 | if (dev == tmp_dev_opp->dev) { | |
480 | dev_opp = tmp_dev_opp; | |
481 | break; | |
482 | } | |
483 | } | |
484 | if (IS_ERR(dev_opp)) { | |
485 | r = PTR_ERR(dev_opp); | |
486 | dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r); | |
487 | goto unlock; | |
488 | } | |
489 | ||
490 | /* Do we have the frequency? */ | |
491 | list_for_each_entry(tmp_opp, &dev_opp->opp_list, node) { | |
492 | if (tmp_opp->rate == freq) { | |
493 | opp = tmp_opp; | |
494 | break; | |
495 | } | |
496 | } | |
497 | if (IS_ERR(opp)) { | |
498 | r = PTR_ERR(opp); | |
499 | goto unlock; | |
500 | } | |
501 | ||
502 | /* Is update really needed? */ | |
503 | if (opp->available == availability_req) | |
504 | goto unlock; | |
505 | /* copy the old data over */ | |
506 | *new_opp = *opp; | |
507 | ||
508 | /* plug in new node */ | |
509 | new_opp->available = availability_req; | |
510 | ||
511 | list_replace_rcu(&opp->node, &new_opp->node); | |
512 | mutex_unlock(&dev_opp_list_lock); | |
513 | synchronize_rcu(); | |
514 | ||
03ca370f MH |
515 | /* Notify the change of the OPP availability */ |
516 | if (availability_req) | |
517 | srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ENABLE, | |
518 | new_opp); | |
519 | else | |
520 | srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_DISABLE, | |
521 | new_opp); | |
522 | ||
e1f60b29 NM |
523 | /* clean up old opp */ |
524 | new_opp = opp; | |
525 | goto out; | |
526 | ||
527 | unlock: | |
528 | mutex_unlock(&dev_opp_list_lock); | |
529 | out: | |
530 | kfree(new_opp); | |
531 | return r; | |
532 | } | |
533 | ||
534 | /** | |
535 | * opp_enable() - Enable a specific OPP | |
536 | * @dev: device for which we do this operation | |
537 | * @freq: OPP frequency to enable | |
538 | * | |
539 | * Enables a provided opp. If the operation is valid, this returns 0, else the | |
540 | * corresponding error value. It is meant to be used for users an OPP available | |
541 | * after being temporarily made unavailable with opp_disable. | |
542 | * | |
543 | * Locking: The internal device_opp and opp structures are RCU protected. | |
544 | * Hence this function indirectly uses RCU and mutex locks to keep the | |
545 | * integrity of the internal data structures. Callers should ensure that | |
546 | * this function is *NOT* called under RCU protection or in contexts where | |
547 | * mutex locking or synchronize_rcu() blocking calls cannot be used. | |
548 | */ | |
549 | int opp_enable(struct device *dev, unsigned long freq) | |
550 | { | |
551 | return opp_set_availability(dev, freq, true); | |
552 | } | |
553 | ||
554 | /** | |
555 | * opp_disable() - Disable a specific OPP | |
556 | * @dev: device for which we do this operation | |
557 | * @freq: OPP frequency to disable | |
558 | * | |
559 | * Disables a provided opp. If the operation is valid, this returns | |
560 | * 0, else the corresponding error value. It is meant to be a temporary | |
561 | * control by users to make this OPP not available until the circumstances are | |
562 | * right to make it available again (with a call to opp_enable). | |
563 | * | |
564 | * Locking: The internal device_opp and opp structures are RCU protected. | |
565 | * Hence this function indirectly uses RCU and mutex locks to keep the | |
566 | * integrity of the internal data structures. Callers should ensure that | |
567 | * this function is *NOT* called under RCU protection or in contexts where | |
568 | * mutex locking or synchronize_rcu() blocking calls cannot be used. | |
569 | */ | |
570 | int opp_disable(struct device *dev, unsigned long freq) | |
571 | { | |
572 | return opp_set_availability(dev, freq, false); | |
573 | } | |
574 | ||
575 | #ifdef CONFIG_CPU_FREQ | |
576 | /** | |
577 | * opp_init_cpufreq_table() - create a cpufreq table for a device | |
578 | * @dev: device for which we do this operation | |
579 | * @table: Cpufreq table returned back to caller | |
580 | * | |
581 | * Generate a cpufreq table for a provided device- this assumes that the | |
582 | * opp list is already initialized and ready for usage. | |
583 | * | |
584 | * This function allocates required memory for the cpufreq table. It is | |
585 | * expected that the caller does the required maintenance such as freeing | |
586 | * the table as required. | |
587 | * | |
588 | * Returns -EINVAL for bad pointers, -ENODEV if the device is not found, -ENOMEM | |
589 | * if no memory available for the operation (table is not populated), returns 0 | |
590 | * if successful and table is populated. | |
591 | * | |
592 | * WARNING: It is important for the callers to ensure refreshing their copy of | |
593 | * the table if any of the mentioned functions have been invoked in the interim. | |
594 | * | |
595 | * Locking: The internal device_opp and opp structures are RCU protected. | |
596 | * To simplify the logic, we pretend we are updater and hold relevant mutex here | |
597 | * Callers should ensure that this function is *NOT* called under RCU protection | |
598 | * or in contexts where mutex locking cannot be used. | |
599 | */ | |
600 | int opp_init_cpufreq_table(struct device *dev, | |
601 | struct cpufreq_frequency_table **table) | |
602 | { | |
603 | struct device_opp *dev_opp; | |
604 | struct opp *opp; | |
605 | struct cpufreq_frequency_table *freq_table; | |
606 | int i = 0; | |
607 | ||
608 | /* Pretend as if I am an updater */ | |
609 | mutex_lock(&dev_opp_list_lock); | |
610 | ||
611 | dev_opp = find_device_opp(dev); | |
612 | if (IS_ERR(dev_opp)) { | |
613 | int r = PTR_ERR(dev_opp); | |
614 | mutex_unlock(&dev_opp_list_lock); | |
615 | dev_err(dev, "%s: Device OPP not found (%d)\n", __func__, r); | |
616 | return r; | |
617 | } | |
618 | ||
619 | freq_table = kzalloc(sizeof(struct cpufreq_frequency_table) * | |
620 | (opp_get_opp_count(dev) + 1), GFP_KERNEL); | |
621 | if (!freq_table) { | |
622 | mutex_unlock(&dev_opp_list_lock); | |
623 | dev_warn(dev, "%s: Unable to allocate frequency table\n", | |
624 | __func__); | |
625 | return -ENOMEM; | |
626 | } | |
627 | ||
628 | list_for_each_entry(opp, &dev_opp->opp_list, node) { | |
629 | if (opp->available) { | |
630 | freq_table[i].index = i; | |
631 | freq_table[i].frequency = opp->rate / 1000; | |
632 | i++; | |
633 | } | |
634 | } | |
635 | mutex_unlock(&dev_opp_list_lock); | |
636 | ||
637 | freq_table[i].index = i; | |
638 | freq_table[i].frequency = CPUFREQ_TABLE_END; | |
639 | ||
640 | *table = &freq_table[0]; | |
641 | ||
642 | return 0; | |
643 | } | |
99f381d3 NM |
644 | |
645 | /** | |
646 | * opp_free_cpufreq_table() - free the cpufreq table | |
647 | * @dev: device for which we do this operation | |
648 | * @table: table to free | |
649 | * | |
650 | * Free up the table allocated by opp_init_cpufreq_table | |
651 | */ | |
652 | void opp_free_cpufreq_table(struct device *dev, | |
653 | struct cpufreq_frequency_table **table) | |
654 | { | |
655 | if (!table) | |
656 | return; | |
657 | ||
658 | kfree(*table); | |
659 | *table = NULL; | |
660 | } | |
e1f60b29 | 661 | #endif /* CONFIG_CPU_FREQ */ |
03ca370f MH |
662 | |
663 | /** | |
664 | * opp_get_notifier() - find notifier_head of the device with opp | |
665 | * @dev: device pointer used to lookup device OPPs. | |
666 | */ | |
667 | struct srcu_notifier_head *opp_get_notifier(struct device *dev) | |
668 | { | |
669 | struct device_opp *dev_opp = find_device_opp(dev); | |
670 | ||
671 | if (IS_ERR(dev_opp)) | |
156acb16 | 672 | return ERR_CAST(dev_opp); /* matching type */ |
03ca370f MH |
673 | |
674 | return &dev_opp->head; | |
675 | } |