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bd9a4c7d OBC |
1 | /* |
2 | * Hardware spinlock framework | |
3 | * | |
4 | * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com | |
5 | * | |
6 | * Contact: Ohad Ben-Cohen <ohad@wizery.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify it | |
9 | * under the terms of the GNU General Public License version 2 as published | |
10 | * by the Free Software Foundation. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | */ | |
17 | ||
18 | #define pr_fmt(fmt) "%s: " fmt, __func__ | |
19 | ||
20 | #include <linux/kernel.h> | |
21 | #include <linux/module.h> | |
22 | #include <linux/spinlock.h> | |
23 | #include <linux/types.h> | |
24 | #include <linux/err.h> | |
25 | #include <linux/jiffies.h> | |
26 | #include <linux/radix-tree.h> | |
27 | #include <linux/hwspinlock.h> | |
28 | #include <linux/pm_runtime.h> | |
93b465c2 | 29 | #include <linux/mutex.h> |
bd9a4c7d OBC |
30 | |
31 | #include "hwspinlock_internal.h" | |
32 | ||
33 | /* radix tree tags */ | |
34 | #define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */ | |
35 | ||
36 | /* | |
37 | * A radix tree is used to maintain the available hwspinlock instances. | |
38 | * The tree associates hwspinlock pointers with their integer key id, | |
39 | * and provides easy-to-use API which makes the hwspinlock core code simple | |
40 | * and easy to read. | |
41 | * | |
42 | * Radix trees are quick on lookups, and reasonably efficient in terms of | |
43 | * storage, especially with high density usages such as this framework | |
44 | * requires (a continuous range of integer keys, beginning with zero, is | |
45 | * used as the ID's of the hwspinlock instances). | |
46 | * | |
47 | * The radix tree API supports tagging items in the tree, which this | |
48 | * framework uses to mark unused hwspinlock instances (see the | |
49 | * HWSPINLOCK_UNUSED tag above). As a result, the process of querying the | |
50 | * tree, looking for an unused hwspinlock instance, is now reduced to a | |
51 | * single radix tree API call. | |
52 | */ | |
53 | static RADIX_TREE(hwspinlock_tree, GFP_KERNEL); | |
54 | ||
55 | /* | |
93b465c2 | 56 | * Synchronization of access to the tree is achieved using this mutex, |
bd9a4c7d | 57 | * as the radix-tree API requires that users provide all synchronisation. |
93b465c2 | 58 | * A mutex is needed because we're using non-atomic radix tree allocations. |
bd9a4c7d | 59 | */ |
93b465c2 JG |
60 | static DEFINE_MUTEX(hwspinlock_tree_lock); |
61 | ||
bd9a4c7d OBC |
62 | |
63 | /** | |
64 | * __hwspin_trylock() - attempt to lock a specific hwspinlock | |
65 | * @hwlock: an hwspinlock which we want to trylock | |
66 | * @mode: controls whether local interrupts are disabled or not | |
67 | * @flags: a pointer where the caller's interrupt state will be saved at (if | |
68 | * requested) | |
69 | * | |
70 | * This function attempts to lock an hwspinlock, and will immediately | |
71 | * fail if the hwspinlock is already taken. | |
72 | * | |
73 | * Upon a successful return from this function, preemption (and possibly | |
74 | * interrupts) is disabled, so the caller must not sleep, and is advised to | |
75 | * release the hwspinlock as soon as possible. This is required in order to | |
76 | * minimize remote cores polling on the hardware interconnect. | |
77 | * | |
78 | * The user decides whether local interrupts are disabled or not, and if yes, | |
79 | * whether he wants their previous state to be saved. It is up to the user | |
80 | * to choose the appropriate @mode of operation, exactly the same way users | |
81 | * should decide between spin_trylock, spin_trylock_irq and | |
82 | * spin_trylock_irqsave. | |
83 | * | |
84 | * Returns 0 if we successfully locked the hwspinlock or -EBUSY if | |
85 | * the hwspinlock was already taken. | |
86 | * This function will never sleep. | |
87 | */ | |
88 | int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags) | |
89 | { | |
90 | int ret; | |
91 | ||
92 | BUG_ON(!hwlock); | |
93 | BUG_ON(!flags && mode == HWLOCK_IRQSTATE); | |
94 | ||
95 | /* | |
96 | * This spin_lock{_irq, _irqsave} serves three purposes: | |
97 | * | |
98 | * 1. Disable preemption, in order to minimize the period of time | |
99 | * in which the hwspinlock is taken. This is important in order | |
100 | * to minimize the possible polling on the hardware interconnect | |
101 | * by a remote user of this lock. | |
102 | * 2. Make the hwspinlock SMP-safe (so we can take it from | |
103 | * additional contexts on the local host). | |
104 | * 3. Ensure that in_atomic/might_sleep checks catch potential | |
105 | * problems with hwspinlock usage (e.g. scheduler checks like | |
106 | * 'scheduling while atomic' etc.) | |
107 | */ | |
108 | if (mode == HWLOCK_IRQSTATE) | |
109 | ret = spin_trylock_irqsave(&hwlock->lock, *flags); | |
110 | else if (mode == HWLOCK_IRQ) | |
111 | ret = spin_trylock_irq(&hwlock->lock); | |
112 | else | |
113 | ret = spin_trylock(&hwlock->lock); | |
114 | ||
115 | /* is lock already taken by another context on the local cpu ? */ | |
116 | if (!ret) | |
117 | return -EBUSY; | |
118 | ||
119 | /* try to take the hwspinlock device */ | |
300bab97 | 120 | ret = hwlock->bank->ops->trylock(hwlock); |
bd9a4c7d OBC |
121 | |
122 | /* if hwlock is already taken, undo spin_trylock_* and exit */ | |
123 | if (!ret) { | |
124 | if (mode == HWLOCK_IRQSTATE) | |
125 | spin_unlock_irqrestore(&hwlock->lock, *flags); | |
126 | else if (mode == HWLOCK_IRQ) | |
127 | spin_unlock_irq(&hwlock->lock); | |
128 | else | |
129 | spin_unlock(&hwlock->lock); | |
130 | ||
131 | return -EBUSY; | |
132 | } | |
133 | ||
134 | /* | |
135 | * We can be sure the other core's memory operations | |
136 | * are observable to us only _after_ we successfully take | |
137 | * the hwspinlock, and we must make sure that subsequent memory | |
138 | * operations (both reads and writes) will not be reordered before | |
139 | * we actually took the hwspinlock. | |
140 | * | |
141 | * Note: the implicit memory barrier of the spinlock above is too | |
142 | * early, so we need this additional explicit memory barrier. | |
143 | */ | |
144 | mb(); | |
145 | ||
146 | return 0; | |
147 | } | |
148 | EXPORT_SYMBOL_GPL(__hwspin_trylock); | |
149 | ||
150 | /** | |
151 | * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit | |
152 | * @hwlock: the hwspinlock to be locked | |
153 | * @timeout: timeout value in msecs | |
154 | * @mode: mode which controls whether local interrupts are disabled or not | |
155 | * @flags: a pointer to where the caller's interrupt state will be saved at (if | |
156 | * requested) | |
157 | * | |
158 | * This function locks the given @hwlock. If the @hwlock | |
159 | * is already taken, the function will busy loop waiting for it to | |
160 | * be released, but give up after @timeout msecs have elapsed. | |
161 | * | |
162 | * Upon a successful return from this function, preemption is disabled | |
163 | * (and possibly local interrupts, too), so the caller must not sleep, | |
164 | * and is advised to release the hwspinlock as soon as possible. | |
165 | * This is required in order to minimize remote cores polling on the | |
166 | * hardware interconnect. | |
167 | * | |
168 | * The user decides whether local interrupts are disabled or not, and if yes, | |
169 | * whether he wants their previous state to be saved. It is up to the user | |
170 | * to choose the appropriate @mode of operation, exactly the same way users | |
171 | * should decide between spin_lock, spin_lock_irq and spin_lock_irqsave. | |
172 | * | |
173 | * Returns 0 when the @hwlock was successfully taken, and an appropriate | |
174 | * error code otherwise (most notably -ETIMEDOUT if the @hwlock is still | |
175 | * busy after @timeout msecs). The function will never sleep. | |
176 | */ | |
177 | int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to, | |
178 | int mode, unsigned long *flags) | |
179 | { | |
180 | int ret; | |
181 | unsigned long expire; | |
182 | ||
183 | expire = msecs_to_jiffies(to) + jiffies; | |
184 | ||
185 | for (;;) { | |
186 | /* Try to take the hwspinlock */ | |
187 | ret = __hwspin_trylock(hwlock, mode, flags); | |
188 | if (ret != -EBUSY) | |
189 | break; | |
190 | ||
191 | /* | |
192 | * The lock is already taken, let's check if the user wants | |
193 | * us to try again | |
194 | */ | |
195 | if (time_is_before_eq_jiffies(expire)) | |
196 | return -ETIMEDOUT; | |
197 | ||
198 | /* | |
199 | * Allow platform-specific relax handlers to prevent | |
200 | * hogging the interconnect (no sleeping, though) | |
201 | */ | |
300bab97 OBC |
202 | if (hwlock->bank->ops->relax) |
203 | hwlock->bank->ops->relax(hwlock); | |
bd9a4c7d OBC |
204 | } |
205 | ||
206 | return ret; | |
207 | } | |
208 | EXPORT_SYMBOL_GPL(__hwspin_lock_timeout); | |
209 | ||
210 | /** | |
211 | * __hwspin_unlock() - unlock a specific hwspinlock | |
212 | * @hwlock: a previously-acquired hwspinlock which we want to unlock | |
213 | * @mode: controls whether local interrupts needs to be restored or not | |
214 | * @flags: previous caller's interrupt state to restore (if requested) | |
215 | * | |
216 | * This function will unlock a specific hwspinlock, enable preemption and | |
217 | * (possibly) enable interrupts or restore their previous state. | |
218 | * @hwlock must be already locked before calling this function: it is a bug | |
219 | * to call unlock on a @hwlock that is already unlocked. | |
220 | * | |
221 | * The user decides whether local interrupts should be enabled or not, and | |
222 | * if yes, whether he wants their previous state to be restored. It is up | |
223 | * to the user to choose the appropriate @mode of operation, exactly the | |
224 | * same way users decide between spin_unlock, spin_unlock_irq and | |
225 | * spin_unlock_irqrestore. | |
226 | * | |
227 | * The function will never sleep. | |
228 | */ | |
229 | void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags) | |
230 | { | |
231 | BUG_ON(!hwlock); | |
232 | BUG_ON(!flags && mode == HWLOCK_IRQSTATE); | |
233 | ||
234 | /* | |
235 | * We must make sure that memory operations (both reads and writes), | |
236 | * done before unlocking the hwspinlock, will not be reordered | |
237 | * after the lock is released. | |
238 | * | |
239 | * That's the purpose of this explicit memory barrier. | |
240 | * | |
241 | * Note: the memory barrier induced by the spin_unlock below is too | |
242 | * late; the other core is going to access memory soon after it will | |
243 | * take the hwspinlock, and by then we want to be sure our memory | |
244 | * operations are already observable. | |
245 | */ | |
246 | mb(); | |
247 | ||
300bab97 | 248 | hwlock->bank->ops->unlock(hwlock); |
bd9a4c7d OBC |
249 | |
250 | /* Undo the spin_trylock{_irq, _irqsave} called while locking */ | |
251 | if (mode == HWLOCK_IRQSTATE) | |
252 | spin_unlock_irqrestore(&hwlock->lock, *flags); | |
253 | else if (mode == HWLOCK_IRQ) | |
254 | spin_unlock_irq(&hwlock->lock); | |
255 | else | |
256 | spin_unlock(&hwlock->lock); | |
257 | } | |
258 | EXPORT_SYMBOL_GPL(__hwspin_unlock); | |
259 | ||
300bab97 | 260 | static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id) |
bd9a4c7d OBC |
261 | { |
262 | struct hwspinlock *tmp; | |
263 | int ret; | |
264 | ||
93b465c2 | 265 | mutex_lock(&hwspinlock_tree_lock); |
bd9a4c7d | 266 | |
300bab97 OBC |
267 | ret = radix_tree_insert(&hwspinlock_tree, id, hwlock); |
268 | if (ret) { | |
269 | if (ret == -EEXIST) | |
270 | pr_err("hwspinlock id %d already exists!\n", id); | |
bd9a4c7d | 271 | goto out; |
300bab97 | 272 | } |
bd9a4c7d OBC |
273 | |
274 | /* mark this hwspinlock as available */ | |
300bab97 | 275 | tmp = radix_tree_tag_set(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); |
bd9a4c7d OBC |
276 | |
277 | /* self-sanity check which should never fail */ | |
278 | WARN_ON(tmp != hwlock); | |
279 | ||
280 | out: | |
93b465c2 | 281 | mutex_unlock(&hwspinlock_tree_lock); |
300bab97 | 282 | return 0; |
bd9a4c7d | 283 | } |
bd9a4c7d | 284 | |
300bab97 | 285 | static struct hwspinlock *hwspin_lock_unregister_single(unsigned int id) |
bd9a4c7d OBC |
286 | { |
287 | struct hwspinlock *hwlock = NULL; | |
288 | int ret; | |
289 | ||
93b465c2 | 290 | mutex_lock(&hwspinlock_tree_lock); |
bd9a4c7d OBC |
291 | |
292 | /* make sure the hwspinlock is not in use (tag is set) */ | |
293 | ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); | |
294 | if (ret == 0) { | |
295 | pr_err("hwspinlock %d still in use (or not present)\n", id); | |
296 | goto out; | |
297 | } | |
298 | ||
299 | hwlock = radix_tree_delete(&hwspinlock_tree, id); | |
300 | if (!hwlock) { | |
301 | pr_err("failed to delete hwspinlock %d\n", id); | |
302 | goto out; | |
303 | } | |
304 | ||
305 | out: | |
93b465c2 | 306 | mutex_unlock(&hwspinlock_tree_lock); |
bd9a4c7d OBC |
307 | return hwlock; |
308 | } | |
300bab97 OBC |
309 | |
310 | /** | |
311 | * hwspin_lock_register() - register a new hw spinlock device | |
312 | * @bank: the hwspinlock device, which usually provides numerous hw locks | |
313 | * @dev: the backing device | |
314 | * @ops: hwspinlock handlers for this device | |
315 | * @base_id: id of the first hardware spinlock in this bank | |
316 | * @num_locks: number of hwspinlocks provided by this device | |
317 | * | |
318 | * This function should be called from the underlying platform-specific | |
319 | * implementation, to register a new hwspinlock device instance. | |
320 | * | |
321 | * Should be called from a process context (might sleep) | |
322 | * | |
323 | * Returns 0 on success, or an appropriate error code on failure | |
324 | */ | |
325 | int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev, | |
326 | const struct hwspinlock_ops *ops, int base_id, int num_locks) | |
327 | { | |
328 | struct hwspinlock *hwlock; | |
329 | int ret = 0, i; | |
330 | ||
331 | if (!bank || !ops || !dev || !num_locks || !ops->trylock || | |
332 | !ops->unlock) { | |
333 | pr_err("invalid parameters\n"); | |
334 | return -EINVAL; | |
335 | } | |
336 | ||
337 | bank->dev = dev; | |
338 | bank->ops = ops; | |
339 | bank->base_id = base_id; | |
340 | bank->num_locks = num_locks; | |
341 | ||
342 | for (i = 0; i < num_locks; i++) { | |
343 | hwlock = &bank->lock[i]; | |
344 | ||
345 | spin_lock_init(&hwlock->lock); | |
346 | hwlock->bank = bank; | |
347 | ||
476a7eeb | 348 | ret = hwspin_lock_register_single(hwlock, base_id + i); |
300bab97 OBC |
349 | if (ret) |
350 | goto reg_failed; | |
351 | } | |
352 | ||
353 | return 0; | |
354 | ||
355 | reg_failed: | |
356 | while (--i >= 0) | |
476a7eeb | 357 | hwspin_lock_unregister_single(base_id + i); |
300bab97 OBC |
358 | return ret; |
359 | } | |
360 | EXPORT_SYMBOL_GPL(hwspin_lock_register); | |
361 | ||
362 | /** | |
363 | * hwspin_lock_unregister() - unregister an hw spinlock device | |
364 | * @bank: the hwspinlock device, which usually provides numerous hw locks | |
365 | * | |
366 | * This function should be called from the underlying platform-specific | |
367 | * implementation, to unregister an existing (and unused) hwspinlock. | |
368 | * | |
369 | * Should be called from a process context (might sleep) | |
370 | * | |
371 | * Returns 0 on success, or an appropriate error code on failure | |
372 | */ | |
373 | int hwspin_lock_unregister(struct hwspinlock_device *bank) | |
374 | { | |
375 | struct hwspinlock *hwlock, *tmp; | |
376 | int i; | |
377 | ||
378 | for (i = 0; i < bank->num_locks; i++) { | |
379 | hwlock = &bank->lock[i]; | |
380 | ||
381 | tmp = hwspin_lock_unregister_single(bank->base_id + i); | |
382 | if (!tmp) | |
383 | return -EBUSY; | |
384 | ||
385 | /* self-sanity check that should never fail */ | |
386 | WARN_ON(tmp != hwlock); | |
387 | } | |
388 | ||
389 | return 0; | |
390 | } | |
bd9a4c7d OBC |
391 | EXPORT_SYMBOL_GPL(hwspin_lock_unregister); |
392 | ||
393 | /** | |
394 | * __hwspin_lock_request() - tag an hwspinlock as used and power it up | |
395 | * | |
396 | * This is an internal function that prepares an hwspinlock instance | |
397 | * before it is given to the user. The function assumes that | |
398 | * hwspinlock_tree_lock is taken. | |
399 | * | |
400 | * Returns 0 or positive to indicate success, and a negative value to | |
401 | * indicate an error (with the appropriate error code) | |
402 | */ | |
403 | static int __hwspin_lock_request(struct hwspinlock *hwlock) | |
404 | { | |
300bab97 | 405 | struct device *dev = hwlock->bank->dev; |
bd9a4c7d OBC |
406 | struct hwspinlock *tmp; |
407 | int ret; | |
408 | ||
409 | /* prevent underlying implementation from being removed */ | |
300bab97 OBC |
410 | if (!try_module_get(dev->driver->owner)) { |
411 | dev_err(dev, "%s: can't get owner\n", __func__); | |
bd9a4c7d OBC |
412 | return -EINVAL; |
413 | } | |
414 | ||
415 | /* notify PM core that power is now needed */ | |
300bab97 | 416 | ret = pm_runtime_get_sync(dev); |
bd9a4c7d | 417 | if (ret < 0) { |
300bab97 | 418 | dev_err(dev, "%s: can't power on device\n", __func__); |
bd9a4c7d OBC |
419 | return ret; |
420 | } | |
421 | ||
422 | /* mark hwspinlock as used, should not fail */ | |
300bab97 | 423 | tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock), |
bd9a4c7d OBC |
424 | HWSPINLOCK_UNUSED); |
425 | ||
426 | /* self-sanity check that should never fail */ | |
427 | WARN_ON(tmp != hwlock); | |
428 | ||
429 | return ret; | |
430 | } | |
431 | ||
432 | /** | |
433 | * hwspin_lock_get_id() - retrieve id number of a given hwspinlock | |
434 | * @hwlock: a valid hwspinlock instance | |
435 | * | |
436 | * Returns the id number of a given @hwlock, or -EINVAL if @hwlock is invalid. | |
437 | */ | |
438 | int hwspin_lock_get_id(struct hwspinlock *hwlock) | |
439 | { | |
440 | if (!hwlock) { | |
441 | pr_err("invalid hwlock\n"); | |
442 | return -EINVAL; | |
443 | } | |
444 | ||
300bab97 | 445 | return hwlock_to_id(hwlock); |
bd9a4c7d OBC |
446 | } |
447 | EXPORT_SYMBOL_GPL(hwspin_lock_get_id); | |
448 | ||
449 | /** | |
450 | * hwspin_lock_request() - request an hwspinlock | |
451 | * | |
452 | * This function should be called by users of the hwspinlock device, | |
453 | * in order to dynamically assign them an unused hwspinlock. | |
454 | * Usually the user of this lock will then have to communicate the lock's id | |
455 | * to the remote core before it can be used for synchronization (to get the | |
456 | * id of a given hwlock, use hwspin_lock_get_id()). | |
457 | * | |
93b465c2 | 458 | * Should be called from a process context (might sleep) |
bd9a4c7d OBC |
459 | * |
460 | * Returns the address of the assigned hwspinlock, or NULL on error | |
461 | */ | |
462 | struct hwspinlock *hwspin_lock_request(void) | |
463 | { | |
464 | struct hwspinlock *hwlock; | |
465 | int ret; | |
466 | ||
93b465c2 | 467 | mutex_lock(&hwspinlock_tree_lock); |
bd9a4c7d OBC |
468 | |
469 | /* look for an unused lock */ | |
470 | ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock, | |
471 | 0, 1, HWSPINLOCK_UNUSED); | |
472 | if (ret == 0) { | |
473 | pr_warn("a free hwspinlock is not available\n"); | |
474 | hwlock = NULL; | |
475 | goto out; | |
476 | } | |
477 | ||
478 | /* sanity check that should never fail */ | |
479 | WARN_ON(ret > 1); | |
480 | ||
481 | /* mark as used and power up */ | |
482 | ret = __hwspin_lock_request(hwlock); | |
483 | if (ret < 0) | |
484 | hwlock = NULL; | |
485 | ||
486 | out: | |
93b465c2 | 487 | mutex_unlock(&hwspinlock_tree_lock); |
bd9a4c7d OBC |
488 | return hwlock; |
489 | } | |
490 | EXPORT_SYMBOL_GPL(hwspin_lock_request); | |
491 | ||
492 | /** | |
493 | * hwspin_lock_request_specific() - request for a specific hwspinlock | |
494 | * @id: index of the specific hwspinlock that is requested | |
495 | * | |
496 | * This function should be called by users of the hwspinlock module, | |
497 | * in order to assign them a specific hwspinlock. | |
498 | * Usually early board code will be calling this function in order to | |
499 | * reserve specific hwspinlock ids for predefined purposes. | |
500 | * | |
93b465c2 | 501 | * Should be called from a process context (might sleep) |
bd9a4c7d OBC |
502 | * |
503 | * Returns the address of the assigned hwspinlock, or NULL on error | |
504 | */ | |
505 | struct hwspinlock *hwspin_lock_request_specific(unsigned int id) | |
506 | { | |
507 | struct hwspinlock *hwlock; | |
508 | int ret; | |
509 | ||
93b465c2 | 510 | mutex_lock(&hwspinlock_tree_lock); |
bd9a4c7d OBC |
511 | |
512 | /* make sure this hwspinlock exists */ | |
513 | hwlock = radix_tree_lookup(&hwspinlock_tree, id); | |
514 | if (!hwlock) { | |
515 | pr_warn("hwspinlock %u does not exist\n", id); | |
516 | goto out; | |
517 | } | |
518 | ||
519 | /* sanity check (this shouldn't happen) */ | |
300bab97 | 520 | WARN_ON(hwlock_to_id(hwlock) != id); |
bd9a4c7d OBC |
521 | |
522 | /* make sure this hwspinlock is unused */ | |
523 | ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); | |
524 | if (ret == 0) { | |
525 | pr_warn("hwspinlock %u is already in use\n", id); | |
526 | hwlock = NULL; | |
527 | goto out; | |
528 | } | |
529 | ||
530 | /* mark as used and power up */ | |
531 | ret = __hwspin_lock_request(hwlock); | |
532 | if (ret < 0) | |
533 | hwlock = NULL; | |
534 | ||
535 | out: | |
93b465c2 | 536 | mutex_unlock(&hwspinlock_tree_lock); |
bd9a4c7d OBC |
537 | return hwlock; |
538 | } | |
539 | EXPORT_SYMBOL_GPL(hwspin_lock_request_specific); | |
540 | ||
541 | /** | |
542 | * hwspin_lock_free() - free a specific hwspinlock | |
543 | * @hwlock: the specific hwspinlock to free | |
544 | * | |
545 | * This function mark @hwlock as free again. | |
546 | * Should only be called with an @hwlock that was retrieved from | |
547 | * an earlier call to omap_hwspin_lock_request{_specific}. | |
548 | * | |
93b465c2 | 549 | * Should be called from a process context (might sleep) |
bd9a4c7d OBC |
550 | * |
551 | * Returns 0 on success, or an appropriate error code on failure | |
552 | */ | |
553 | int hwspin_lock_free(struct hwspinlock *hwlock) | |
554 | { | |
300bab97 | 555 | struct device *dev = hwlock->bank->dev; |
bd9a4c7d OBC |
556 | struct hwspinlock *tmp; |
557 | int ret; | |
558 | ||
559 | if (!hwlock) { | |
560 | pr_err("invalid hwlock\n"); | |
561 | return -EINVAL; | |
562 | } | |
563 | ||
93b465c2 | 564 | mutex_lock(&hwspinlock_tree_lock); |
bd9a4c7d OBC |
565 | |
566 | /* make sure the hwspinlock is used */ | |
300bab97 | 567 | ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock), |
bd9a4c7d OBC |
568 | HWSPINLOCK_UNUSED); |
569 | if (ret == 1) { | |
300bab97 | 570 | dev_err(dev, "%s: hwlock is already free\n", __func__); |
bd9a4c7d OBC |
571 | dump_stack(); |
572 | ret = -EINVAL; | |
573 | goto out; | |
574 | } | |
575 | ||
576 | /* notify the underlying device that power is not needed */ | |
300bab97 | 577 | ret = pm_runtime_put(dev); |
bd9a4c7d OBC |
578 | if (ret < 0) |
579 | goto out; | |
580 | ||
581 | /* mark this hwspinlock as available */ | |
300bab97 | 582 | tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock), |
bd9a4c7d OBC |
583 | HWSPINLOCK_UNUSED); |
584 | ||
585 | /* sanity check (this shouldn't happen) */ | |
586 | WARN_ON(tmp != hwlock); | |
587 | ||
300bab97 | 588 | module_put(dev->driver->owner); |
bd9a4c7d OBC |
589 | |
590 | out: | |
93b465c2 | 591 | mutex_unlock(&hwspinlock_tree_lock); |
bd9a4c7d OBC |
592 | return ret; |
593 | } | |
594 | EXPORT_SYMBOL_GPL(hwspin_lock_free); | |
595 | ||
596 | MODULE_LICENSE("GPL v2"); | |
597 | MODULE_DESCRIPTION("Hardware spinlock interface"); | |
598 | MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>"); |