1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Hardware spinlock framework
4 *
5 * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
6 *
7 * Contact: Ohad Ben-Cohen <ohad@wizery.com>
8 */
9
10 #define pr_fmt(fmt) "%s: " fmt, __func__
11
12 #include <linux/delay.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/spinlock.h>
16 #include <linux/types.h>
17 #include <linux/err.h>
18 #include <linux/jiffies.h>
19 #include <linux/radix-tree.h>
20 #include <linux/hwspinlock.h>
21 #include <linux/pm_runtime.h>
22 #include <linux/mutex.h>
23 #include <linux/of.h>
24
25 #include "hwspinlock_internal.h"
26
27 /* retry delay used in atomic context */
28 #define HWSPINLOCK_RETRY_DELAY_US 100
29
30 /* radix tree tags */
31 #define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */
32
33 /*
34 * A radix tree is used to maintain the available hwspinlock instances.
35 * The tree associates hwspinlock pointers with their integer key id,
36 * and provides easy-to-use API which makes the hwspinlock core code simple
37 * and easy to read.
38 *
39 * Radix trees are quick on lookups, and reasonably efficient in terms of
40 * storage, especially with high density usages such as this framework
41 * requires (a continuous range of integer keys, beginning with zero, is
42 * used as the ID's of the hwspinlock instances).
43 *
44 * The radix tree API supports tagging items in the tree, which this
45 * framework uses to mark unused hwspinlock instances (see the
46 * HWSPINLOCK_UNUSED tag above). As a result, the process of querying the
47 * tree, looking for an unused hwspinlock instance, is now reduced to a
48 * single radix tree API call.
49 */
50 static RADIX_TREE(hwspinlock_tree, GFP_KERNEL);
51
52 /*
53 * Synchronization of access to the tree is achieved using this mutex,
54 * as the radix-tree API requires that users provide all synchronisation.
55 * A mutex is needed because we're using non-atomic radix tree allocations.
56 */
57 static DEFINE_MUTEX(hwspinlock_tree_lock);
58
59
60 /**
61 * __hwspin_trylock() - attempt to lock a specific hwspinlock
62 * @hwlock: an hwspinlock which we want to trylock
63 * @mode: controls whether local interrupts are disabled or not
64 * @flags: a pointer where the caller's interrupt state will be saved at (if
65 * requested)
66 *
67 * This function attempts to lock an hwspinlock, and will immediately
68 * fail if the hwspinlock is already taken.
69 *
70 * Caution: If the mode is HWLOCK_RAW, that means user must protect the routine
71 * of getting hardware lock with mutex or spinlock. Since in some scenarios,
72 * user need some time-consuming or sleepable operations under the hardware
73 * lock, they need one sleepable lock (like mutex) to protect the operations.
74 *
75 * If the mode is neither HWLOCK_IN_ATOMIC nor HWLOCK_RAW, upon a successful
76 * return from this function, preemption (and possibly interrupts) is disabled,
77 * so the caller must not sleep, and is advised to release the hwspinlock as
78 * soon as possible. This is required in order to minimize remote cores polling
79 * on the hardware interconnect.
80 *
81 * The user decides whether local interrupts are disabled or not, and if yes,
82 * whether he wants their previous state to be saved. It is up to the user
83 * to choose the appropriate @mode of operation, exactly the same way users
84 * should decide between spin_trylock, spin_trylock_irq and
85 * spin_trylock_irqsave.
86 *
87 * Returns 0 if we successfully locked the hwspinlock or -EBUSY if
88 * the hwspinlock was already taken.
89 * This function will never sleep.
90 */
91 int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
92 {
93 int ret;
94
95 BUG_ON(!hwlock);
96 BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
97
98 /*
99 * This spin_lock{_irq, _irqsave} serves three purposes:
100 *
101 * 1. Disable preemption, in order to minimize the period of time
102 * in which the hwspinlock is taken. This is important in order
103 * to minimize the possible polling on the hardware interconnect
104 * by a remote user of this lock.
105 * 2. Make the hwspinlock SMP-safe (so we can take it from
106 * additional contexts on the local host).
107 * 3. Ensure that in_atomic/might_sleep checks catch potential
108 * problems with hwspinlock usage (e.g. scheduler checks like
109 * 'scheduling while atomic' etc.)
110 */
111 switch (mode) {
112 case HWLOCK_IRQSTATE:
113 ret = spin_trylock_irqsave(&hwlock->lock, *flags);
114 break;
115 case HWLOCK_IRQ:
116 ret = spin_trylock_irq(&hwlock->lock);
117 break;
118 case HWLOCK_RAW:
119 case HWLOCK_IN_ATOMIC:
120 ret = 1;
121 break;
122 default:
123 ret = spin_trylock(&hwlock->lock);
124 break;
125 }
126
127 /* is lock already taken by another context on the local cpu ? */
128 if (!ret)
129 return -EBUSY;
130
131 /* try to take the hwspinlock device */
132 ret = hwlock->bank->ops->trylock(hwlock);
133
134 /* if hwlock is already taken, undo spin_trylock_* and exit */
135 if (!ret) {
136 switch (mode) {
137 case HWLOCK_IRQSTATE:
138 spin_unlock_irqrestore(&hwlock->lock, *flags);
139 break;
140 case HWLOCK_IRQ:
141 spin_unlock_irq(&hwlock->lock);
142 break;
143 case HWLOCK_RAW:
144 case HWLOCK_IN_ATOMIC:
145 /* Nothing to do */
146 break;
147 default:
148 spin_unlock(&hwlock->lock);
149 break;
150 }
151
152 return -EBUSY;
153 }
154
155 /*
156 * We can be sure the other core's memory operations
157 * are observable to us only _after_ we successfully take
158 * the hwspinlock, and we must make sure that subsequent memory
159 * operations (both reads and writes) will not be reordered before
160 * we actually took the hwspinlock.
161 *
162 * Note: the implicit memory barrier of the spinlock above is too
163 * early, so we need this additional explicit memory barrier.
164 */
165 mb();
166
167 return 0;
168 }
169 EXPORT_SYMBOL_GPL(__hwspin_trylock);
170
171 /**
172 * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit
173 * @hwlock: the hwspinlock to be locked
174 * @timeout: timeout value in msecs
175 * @mode: mode which controls whether local interrupts are disabled or not
176 * @flags: a pointer to where the caller's interrupt state will be saved at (if
177 * requested)
178 *
179 * This function locks the given @hwlock. If the @hwlock
180 * is already taken, the function will busy loop waiting for it to
181 * be released, but give up after @timeout msecs have elapsed.
182 *
183 * Caution: If the mode is HWLOCK_RAW, that means user must protect the routine
184 * of getting hardware lock with mutex or spinlock. Since in some scenarios,
185 * user need some time-consuming or sleepable operations under the hardware
186 * lock, they need one sleepable lock (like mutex) to protect the operations.
187 *
188 * If the mode is HWLOCK_IN_ATOMIC (called from an atomic context) the timeout
189 * is handled with busy-waiting delays, hence shall not exceed few msecs.
190 *
191 * If the mode is neither HWLOCK_IN_ATOMIC nor HWLOCK_RAW, upon a successful
192 * return from this function, preemption (and possibly interrupts) is disabled,
193 * so the caller must not sleep, and is advised to release the hwspinlock as
194 * soon as possible. This is required in order to minimize remote cores polling
195 * on the hardware interconnect.
196 *
197 * The user decides whether local interrupts are disabled or not, and if yes,
198 * whether he wants their previous state to be saved. It is up to the user
199 * to choose the appropriate @mode of operation, exactly the same way users
200 * should decide between spin_lock, spin_lock_irq and spin_lock_irqsave.
201 *
202 * Returns 0 when the @hwlock was successfully taken, and an appropriate
203 * error code otherwise (most notably -ETIMEDOUT if the @hwlock is still
204 * busy after @timeout msecs). The function will never sleep.
205 */
206 int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to,
207 int mode, unsigned long *flags)
208 {
209 int ret;
210 unsigned long expire, atomic_delay = 0;
211
212 expire = msecs_to_jiffies(to) + jiffies;
213
214 for (;;) {
215 /* Try to take the hwspinlock */
216 ret = __hwspin_trylock(hwlock, mode, flags);
217 if (ret != -EBUSY)
218 break;
219
220 /*
221 * The lock is already taken, let's check if the user wants
222 * us to try again
223 */
224 if (mode == HWLOCK_IN_ATOMIC) {
225 udelay(HWSPINLOCK_RETRY_DELAY_US);
226 atomic_delay += HWSPINLOCK_RETRY_DELAY_US;
227 if (atomic_delay > to * 1000)
228 return -ETIMEDOUT;
229 } else {
230 if (time_is_before_eq_jiffies(expire))
231 return -ETIMEDOUT;
232 }
233
234 /*
235 * Allow platform-specific relax handlers to prevent
236 * hogging the interconnect (no sleeping, though)
237 */
238 if (hwlock->bank->ops->relax)
239 hwlock->bank->ops->relax(hwlock);
240 }
241
242 return ret;
243 }
244 EXPORT_SYMBOL_GPL(__hwspin_lock_timeout);
245
246 /**
247 * __hwspin_unlock() - unlock a specific hwspinlock
248 * @hwlock: a previously-acquired hwspinlock which we want to unlock
249 * @mode: controls whether local interrupts needs to be restored or not
250 * @flags: previous caller's interrupt state to restore (if requested)
251 *
252 * This function will unlock a specific hwspinlock, enable preemption and
253 * (possibly) enable interrupts or restore their previous state.
254 * @hwlock must be already locked before calling this function: it is a bug
255 * to call unlock on a @hwlock that is already unlocked.
256 *
257 * The user decides whether local interrupts should be enabled or not, and
258 * if yes, whether he wants their previous state to be restored. It is up
259 * to the user to choose the appropriate @mode of operation, exactly the
260 * same way users decide between spin_unlock, spin_unlock_irq and
261 * spin_unlock_irqrestore.
262 *
263 * The function will never sleep.
264 */
265 void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
266 {
267 BUG_ON(!hwlock);
268 BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
269
270 /*
271 * We must make sure that memory operations (both reads and writes),
272 * done before unlocking the hwspinlock, will not be reordered
273 * after the lock is released.
274 *
275 * That's the purpose of this explicit memory barrier.
276 *
277 * Note: the memory barrier induced by the spin_unlock below is too
278 * late; the other core is going to access memory soon after it will
279 * take the hwspinlock, and by then we want to be sure our memory
280 * operations are already observable.
281 */
282 mb();
283
284 hwlock->bank->ops->unlock(hwlock);
285
286 /* Undo the spin_trylock{_irq, _irqsave} called while locking */
287 switch (mode) {
288 case HWLOCK_IRQSTATE:
289 spin_unlock_irqrestore(&hwlock->lock, *flags);
290 break;
291 case HWLOCK_IRQ:
292 spin_unlock_irq(&hwlock->lock);
293 break;
294 case HWLOCK_RAW:
295 case HWLOCK_IN_ATOMIC:
296 /* Nothing to do */
297 break;
298 default:
299 spin_unlock(&hwlock->lock);
300 break;
301 }
302 }
303 EXPORT_SYMBOL_GPL(__hwspin_unlock);
304
305 /**
306 * of_hwspin_lock_simple_xlate - translate hwlock_spec to return a lock id
307 * @bank: the hwspinlock device bank
308 * @hwlock_spec: hwlock specifier as found in the device tree
309 *
310 * This is a simple translation function, suitable for hwspinlock platform
311 * drivers that only has a lock specifier length of 1.
312 *
313 * Returns a relative index of the lock within a specified bank on success,
314 * or -EINVAL on invalid specifier cell count.
315 */
316 static inline int
317 of_hwspin_lock_simple_xlate(const struct of_phandle_args *hwlock_spec)
318 {
319 if (WARN_ON(hwlock_spec->args_count != 1))
320 return -EINVAL;
321
322 return hwlock_spec->args[0];
323 }
324
325 /**
326 * of_hwspin_lock_get_id() - get lock id for an OF phandle-based specific lock
327 * @np: device node from which to request the specific hwlock
328 * @index: index of the hwlock in the list of values
329 *
330 * This function provides a means for DT users of the hwspinlock module to
331 * get the global lock id of a specific hwspinlock using the phandle of the
332 * hwspinlock device, so that it can be requested using the normal
333 * hwspin_lock_request_specific() API.
334 *
335 * Returns the global lock id number on success, -EPROBE_DEFER if the hwspinlock
336 * device is not yet registered, -EINVAL on invalid args specifier value or an
337 * appropriate error as returned from the OF parsing of the DT client node.
338 */
339 int of_hwspin_lock_get_id(struct device_node *np, int index)
340 {
341 struct of_phandle_args args;
342 struct hwspinlock *hwlock;
343 struct radix_tree_iter iter;
344 void **slot;
345 int id;
346 int ret;
347
348 ret = of_parse_phandle_with_args(np, "hwlocks", "#hwlock-cells", index,
349 &args);
350 if (ret)
351 return ret;
352
353 if (!of_device_is_available(args.np)) {
354 ret = -ENOENT;
355 goto out;
356 }
357
358 /* Find the hwspinlock device: we need its base_id */
359 ret = -EPROBE_DEFER;
360 rcu_read_lock();
361 radix_tree_for_each_slot(slot, &hwspinlock_tree, &iter, 0) {
362 hwlock = radix_tree_deref_slot(slot);
363 if (unlikely(!hwlock))
364 continue;
365 if (radix_tree_deref_retry(hwlock)) {
366 slot = radix_tree_iter_retry(&iter);
367 continue;
368 }
369
370 if (hwlock->bank->dev->of_node == args.np) {
371 ret = 0;
372 break;
373 }
374 }
375 rcu_read_unlock();
376 if (ret < 0)
377 goto out;
378
379 id = of_hwspin_lock_simple_xlate(&args);
380 if (id < 0 || id >= hwlock->bank->num_locks) {
381 ret = -EINVAL;
382 goto out;
383 }
384 id += hwlock->bank->base_id;
385
386 out:
387 of_node_put(args.np);
388 return ret ? ret : id;
389 }
390 EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id);
391
392 /**
393 * of_hwspin_lock_get_id_byname() - get lock id for an specified hwlock name
394 * @np: device node from which to request the specific hwlock
395 * @name: hwlock name
396 *
397 * This function provides a means for DT users of the hwspinlock module to
398 * get the global lock id of a specific hwspinlock using the specified name of
399 * the hwspinlock device, so that it can be requested using the normal
400 * hwspin_lock_request_specific() API.
401 *
402 * Returns the global lock id number on success, -EPROBE_DEFER if the hwspinlock
403 * device is not yet registered, -EINVAL on invalid args specifier value or an
404 * appropriate error as returned from the OF parsing of the DT client node.
405 */
406 int of_hwspin_lock_get_id_byname(struct device_node *np, const char *name)
407 {
408 int index;
409
410 if (!name)
411 return -EINVAL;
412
413 index = of_property_match_string(np, "hwlock-names", name);
414 if (index < 0)
415 return index;
416
417 return of_hwspin_lock_get_id(np, index);
418 }
419 EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id_byname);
420
421 static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id)
422 {
423 struct hwspinlock *tmp;
424 int ret;
425
426 mutex_lock(&hwspinlock_tree_lock);
427
428 ret = radix_tree_insert(&hwspinlock_tree, id, hwlock);
429 if (ret) {
430 if (ret == -EEXIST)
431 pr_err("hwspinlock id %d already exists!\n", id);
432 goto out;
433 }
434
435 /* mark this hwspinlock as available */
436 tmp = radix_tree_tag_set(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
437
438 /* self-sanity check which should never fail */
439 WARN_ON(tmp != hwlock);
440
441 out:
442 mutex_unlock(&hwspinlock_tree_lock);
443 return 0;
444 }
445
446 static struct hwspinlock *hwspin_lock_unregister_single(unsigned int id)
447 {
448 struct hwspinlock *hwlock = NULL;
449 int ret;
450
451 mutex_lock(&hwspinlock_tree_lock);
452
453 /* make sure the hwspinlock is not in use (tag is set) */
454 ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
455 if (ret == 0) {
456 pr_err("hwspinlock %d still in use (or not present)\n", id);
457 goto out;
458 }
459
460 hwlock = radix_tree_delete(&hwspinlock_tree, id);
461 if (!hwlock) {
462 pr_err("failed to delete hwspinlock %d\n", id);
463 goto out;
464 }
465
466 out:
467 mutex_unlock(&hwspinlock_tree_lock);
468 return hwlock;
469 }
470
471 /**
472 * hwspin_lock_register() - register a new hw spinlock device
473 * @bank: the hwspinlock device, which usually provides numerous hw locks
474 * @dev: the backing device
475 * @ops: hwspinlock handlers for this device
476 * @base_id: id of the first hardware spinlock in this bank
477 * @num_locks: number of hwspinlocks provided by this device
478 *
479 * This function should be called from the underlying platform-specific
480 * implementation, to register a new hwspinlock device instance.
481 *
482 * Should be called from a process context (might sleep)
483 *
484 * Returns 0 on success, or an appropriate error code on failure
485 */
486 int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
487 const struct hwspinlock_ops *ops, int base_id, int num_locks)
488 {
489 struct hwspinlock *hwlock;
490 int ret = 0, i;
491
492 if (!bank || !ops || !dev || !num_locks || !ops->trylock ||
493 !ops->unlock) {
494 pr_err("invalid parameters\n");
495 return -EINVAL;
496 }
497
498 bank->dev = dev;
499 bank->ops = ops;
500 bank->base_id = base_id;
501 bank->num_locks = num_locks;
502
503 for (i = 0; i < num_locks; i++) {
504 hwlock = &bank->lock[i];
505
506 spin_lock_init(&hwlock->lock);
507 hwlock->bank = bank;
508
509 ret = hwspin_lock_register_single(hwlock, base_id + i);
510 if (ret)
511 goto reg_failed;
512 }
513
514 return 0;
515
516 reg_failed:
517 while (--i >= 0)
518 hwspin_lock_unregister_single(base_id + i);
519 return ret;
520 }
521 EXPORT_SYMBOL_GPL(hwspin_lock_register);
522
523 /**
524 * hwspin_lock_unregister() - unregister an hw spinlock device
525 * @bank: the hwspinlock device, which usually provides numerous hw locks
526 *
527 * This function should be called from the underlying platform-specific
528 * implementation, to unregister an existing (and unused) hwspinlock.
529 *
530 * Should be called from a process context (might sleep)
531 *
532 * Returns 0 on success, or an appropriate error code on failure
533 */
534 int hwspin_lock_unregister(struct hwspinlock_device *bank)
535 {
536 struct hwspinlock *hwlock, *tmp;
537 int i;
538
539 for (i = 0; i < bank->num_locks; i++) {
540 hwlock = &bank->lock[i];
541
542 tmp = hwspin_lock_unregister_single(bank->base_id + i);
543 if (!tmp)
544 return -EBUSY;
545
546 /* self-sanity check that should never fail */
547 WARN_ON(tmp != hwlock);
548 }
549
550 return 0;
551 }
552 EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
553
554 static void devm_hwspin_lock_unreg(struct device *dev, void *res)
555 {
556 hwspin_lock_unregister(*(struct hwspinlock_device **)res);
557 }
558
559 static int devm_hwspin_lock_device_match(struct device *dev, void *res,
560 void *data)
561 {
562 struct hwspinlock_device **bank = res;
563
564 if (WARN_ON(!bank || !*bank))
565 return 0;
566
567 return *bank == data;
568 }
569
570 /**
571 * devm_hwspin_lock_unregister() - unregister an hw spinlock device for
572 * a managed device
573 * @dev: the backing device
574 * @bank: the hwspinlock device, which usually provides numerous hw locks
575 *
576 * This function should be called from the underlying platform-specific
577 * implementation, to unregister an existing (and unused) hwspinlock.
578 *
579 * Should be called from a process context (might sleep)
580 *
581 * Returns 0 on success, or an appropriate error code on failure
582 */
583 int devm_hwspin_lock_unregister(struct device *dev,
584 struct hwspinlock_device *bank)
585 {
586 int ret;
587
588 ret = devres_release(dev, devm_hwspin_lock_unreg,
589 devm_hwspin_lock_device_match, bank);
590 WARN_ON(ret);
591
592 return ret;
593 }
594 EXPORT_SYMBOL_GPL(devm_hwspin_lock_unregister);
595
596 /**
597 * devm_hwspin_lock_register() - register a new hw spinlock device for
598 * a managed device
599 * @dev: the backing device
600 * @bank: the hwspinlock device, which usually provides numerous hw locks
601 * @ops: hwspinlock handlers for this device
602 * @base_id: id of the first hardware spinlock in this bank
603 * @num_locks: number of hwspinlocks provided by this device
604 *
605 * This function should be called from the underlying platform-specific
606 * implementation, to register a new hwspinlock device instance.
607 *
608 * Should be called from a process context (might sleep)
609 *
610 * Returns 0 on success, or an appropriate error code on failure
611 */
612 int devm_hwspin_lock_register(struct device *dev,
613 struct hwspinlock_device *bank,
614 const struct hwspinlock_ops *ops,
615 int base_id, int num_locks)
616 {
617 struct hwspinlock_device **ptr;
618 int ret;
619
620 ptr = devres_alloc(devm_hwspin_lock_unreg, sizeof(*ptr), GFP_KERNEL);
621 if (!ptr)
622 return -ENOMEM;
623
624 ret = hwspin_lock_register(bank, dev, ops, base_id, num_locks);
625 if (!ret) {
626 *ptr = bank;
627 devres_add(dev, ptr);
628 } else {
629 devres_free(ptr);
630 }
631
632 return ret;
633 }
634 EXPORT_SYMBOL_GPL(devm_hwspin_lock_register);
635
636 /**
637 * __hwspin_lock_request() - tag an hwspinlock as used and power it up
638 *
639 * This is an internal function that prepares an hwspinlock instance
640 * before it is given to the user. The function assumes that
641 * hwspinlock_tree_lock is taken.
642 *
643 * Returns 0 or positive to indicate success, and a negative value to
644 * indicate an error (with the appropriate error code)
645 */
646 static int __hwspin_lock_request(struct hwspinlock *hwlock)
647 {
648 struct device *dev = hwlock->bank->dev;
649 struct hwspinlock *tmp;
650 int ret;
651
652 /* prevent underlying implementation from being removed */
653 if (!try_module_get(dev->driver->owner)) {
654 dev_err(dev, "%s: can't get owner\n", __func__);
655 return -EINVAL;
656 }
657
658 /* notify PM core that power is now needed */
659 ret = pm_runtime_get_sync(dev);
660 if (ret < 0) {
661 dev_err(dev, "%s: can't power on device\n", __func__);
662 pm_runtime_put_noidle(dev);
663 module_put(dev->driver->owner);
664 return ret;
665 }
666
667 /* mark hwspinlock as used, should not fail */
668 tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock),
669 HWSPINLOCK_UNUSED);
670
671 /* self-sanity check that should never fail */
672 WARN_ON(tmp != hwlock);
673
674 return ret;
675 }
676
677 /**
678 * hwspin_lock_get_id() - retrieve id number of a given hwspinlock
679 * @hwlock: a valid hwspinlock instance
680 *
681 * Returns the id number of a given @hwlock, or -EINVAL if @hwlock is invalid.
682 */
683 int hwspin_lock_get_id(struct hwspinlock *hwlock)
684 {
685 if (!hwlock) {
686 pr_err("invalid hwlock\n");
687 return -EINVAL;
688 }
689
690 return hwlock_to_id(hwlock);
691 }
692 EXPORT_SYMBOL_GPL(hwspin_lock_get_id);
693
694 /**
695 * hwspin_lock_request() - request an hwspinlock
696 *
697 * This function should be called by users of the hwspinlock device,
698 * in order to dynamically assign them an unused hwspinlock.
699 * Usually the user of this lock will then have to communicate the lock's id
700 * to the remote core before it can be used for synchronization (to get the
701 * id of a given hwlock, use hwspin_lock_get_id()).
702 *
703 * Should be called from a process context (might sleep)
704 *
705 * Returns the address of the assigned hwspinlock, or NULL on error
706 */
707 struct hwspinlock *hwspin_lock_request(void)
708 {
709 struct hwspinlock *hwlock;
710 int ret;
711
712 mutex_lock(&hwspinlock_tree_lock);
713
714 /* look for an unused lock */
715 ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
716 0, 1, HWSPINLOCK_UNUSED);
717 if (ret == 0) {
718 pr_warn("a free hwspinlock is not available\n");
719 hwlock = NULL;
720 goto out;
721 }
722
723 /* sanity check that should never fail */
724 WARN_ON(ret > 1);
725
726 /* mark as used and power up */
727 ret = __hwspin_lock_request(hwlock);
728 if (ret < 0)
729 hwlock = NULL;
730
731 out:
732 mutex_unlock(&hwspinlock_tree_lock);
733 return hwlock;
734 }
735 EXPORT_SYMBOL_GPL(hwspin_lock_request);
736
737 /**
738 * hwspin_lock_request_specific() - request for a specific hwspinlock
739 * @id: index of the specific hwspinlock that is requested
740 *
741 * This function should be called by users of the hwspinlock module,
742 * in order to assign them a specific hwspinlock.
743 * Usually early board code will be calling this function in order to
744 * reserve specific hwspinlock ids for predefined purposes.
745 *
746 * Should be called from a process context (might sleep)
747 *
748 * Returns the address of the assigned hwspinlock, or NULL on error
749 */
750 struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
751 {
752 struct hwspinlock *hwlock;
753 int ret;
754
755 mutex_lock(&hwspinlock_tree_lock);
756
757 /* make sure this hwspinlock exists */
758 hwlock = radix_tree_lookup(&hwspinlock_tree, id);
759 if (!hwlock) {
760 pr_warn("hwspinlock %u does not exist\n", id);
761 goto out;
762 }
763
764 /* sanity check (this shouldn't happen) */
765 WARN_ON(hwlock_to_id(hwlock) != id);
766
767 /* make sure this hwspinlock is unused */
768 ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
769 if (ret == 0) {
770 pr_warn("hwspinlock %u is already in use\n", id);
771 hwlock = NULL;
772 goto out;
773 }
774
775 /* mark as used and power up */
776 ret = __hwspin_lock_request(hwlock);
777 if (ret < 0)
778 hwlock = NULL;
779
780 out:
781 mutex_unlock(&hwspinlock_tree_lock);
782 return hwlock;
783 }
784 EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
785
786 /**
787 * hwspin_lock_free() - free a specific hwspinlock
788 * @hwlock: the specific hwspinlock to free
789 *
790 * This function mark @hwlock as free again.
791 * Should only be called with an @hwlock that was retrieved from
792 * an earlier call to hwspin_lock_request{_specific}.
793 *
794 * Should be called from a process context (might sleep)
795 *
796 * Returns 0 on success, or an appropriate error code on failure
797 */
798 int hwspin_lock_free(struct hwspinlock *hwlock)
799 {
800 struct device *dev;
801 struct hwspinlock *tmp;
802 int ret;
803
804 if (!hwlock) {
805 pr_err("invalid hwlock\n");
806 return -EINVAL;
807 }
808
809 dev = hwlock->bank->dev;
810 mutex_lock(&hwspinlock_tree_lock);
811
812 /* make sure the hwspinlock is used */
813 ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock),
814 HWSPINLOCK_UNUSED);
815 if (ret == 1) {
816 dev_err(dev, "%s: hwlock is already free\n", __func__);
817 dump_stack();
818 ret = -EINVAL;
819 goto out;
820 }
821
822 /* notify the underlying device that power is not needed */
823 ret = pm_runtime_put(dev);
824 if (ret < 0)
825 goto out;
826
827 /* mark this hwspinlock as available */
828 tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock),
829 HWSPINLOCK_UNUSED);
830
831 /* sanity check (this shouldn't happen) */
832 WARN_ON(tmp != hwlock);
833
834 module_put(dev->driver->owner);
835
836 out:
837 mutex_unlock(&hwspinlock_tree_lock);
838 return ret;
839 }
840 EXPORT_SYMBOL_GPL(hwspin_lock_free);
841
842 static int devm_hwspin_lock_match(struct device *dev, void *res, void *data)
843 {
844 struct hwspinlock **hwlock = res;
845
846 if (WARN_ON(!hwlock || !*hwlock))
847 return 0;
848
849 return *hwlock == data;
850 }
851
852 static void devm_hwspin_lock_release(struct device *dev, void *res)
853 {
854 hwspin_lock_free(*(struct hwspinlock **)res);
855 }
856
857 /**
858 * devm_hwspin_lock_free() - free a specific hwspinlock for a managed device
859 * @dev: the device to free the specific hwspinlock
860 * @hwlock: the specific hwspinlock to free
861 *
862 * This function mark @hwlock as free again.
863 * Should only be called with an @hwlock that was retrieved from
864 * an earlier call to hwspin_lock_request{_specific}.
865 *
866 * Should be called from a process context (might sleep)
867 *
868 * Returns 0 on success, or an appropriate error code on failure
869 */
870 int devm_hwspin_lock_free(struct device *dev, struct hwspinlock *hwlock)
871 {
872 int ret;
873
874 ret = devres_release(dev, devm_hwspin_lock_release,
875 devm_hwspin_lock_match, hwlock);
876 WARN_ON(ret);
877
878 return ret;
879 }
880 EXPORT_SYMBOL_GPL(devm_hwspin_lock_free);
881
882 /**
883 * devm_hwspin_lock_request() - request an hwspinlock for a managed device
884 * @dev: the device to request an hwspinlock
885 *
886 * This function should be called by users of the hwspinlock device,
887 * in order to dynamically assign them an unused hwspinlock.
888 * Usually the user of this lock will then have to communicate the lock's id
889 * to the remote core before it can be used for synchronization (to get the
890 * id of a given hwlock, use hwspin_lock_get_id()).
891 *
892 * Should be called from a process context (might sleep)
893 *
894 * Returns the address of the assigned hwspinlock, or NULL on error
895 */
896 struct hwspinlock *devm_hwspin_lock_request(struct device *dev)
897 {
898 struct hwspinlock **ptr, *hwlock;
899
900 ptr = devres_alloc(devm_hwspin_lock_release, sizeof(*ptr), GFP_KERNEL);
901 if (!ptr)
902 return NULL;
903
904 hwlock = hwspin_lock_request();
905 if (hwlock) {
906 *ptr = hwlock;
907 devres_add(dev, ptr);
908 } else {
909 devres_free(ptr);
910 }
911
912 return hwlock;
913 }
914 EXPORT_SYMBOL_GPL(devm_hwspin_lock_request);
915
916 /**
917 * devm_hwspin_lock_request_specific() - request for a specific hwspinlock for
918 * a managed device
919 * @dev: the device to request the specific hwspinlock
920 * @id: index of the specific hwspinlock that is requested
921 *
922 * This function should be called by users of the hwspinlock module,
923 * in order to assign them a specific hwspinlock.
924 * Usually early board code will be calling this function in order to
925 * reserve specific hwspinlock ids for predefined purposes.
926 *
927 * Should be called from a process context (might sleep)
928 *
929 * Returns the address of the assigned hwspinlock, or NULL on error
930 */
931 struct hwspinlock *devm_hwspin_lock_request_specific(struct device *dev,
932 unsigned int id)
933 {
934 struct hwspinlock **ptr, *hwlock;
935
936 ptr = devres_alloc(devm_hwspin_lock_release, sizeof(*ptr), GFP_KERNEL);
937 if (!ptr)
938 return NULL;
939
940 hwlock = hwspin_lock_request_specific(id);
941 if (hwlock) {
942 *ptr = hwlock;
943 devres_add(dev, ptr);
944 } else {
945 devres_free(ptr);
946 }
947
948 return hwlock;
949 }
950 EXPORT_SYMBOL_GPL(devm_hwspin_lock_request_specific);
951
952 MODULE_LICENSE("GPL v2");
953 MODULE_DESCRIPTION("Hardware spinlock interface");
954 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");