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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 */
50static 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 */
57static 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 *
90 * This function will never sleep.
91 */
92int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
93{
94 int ret;
95
96 if (WARN_ON(!hwlock || (!flags && mode == HWLOCK_IRQSTATE)))
97 return -EINVAL;
98
99 /*
100 * This spin_lock{_irq, _irqsave} serves three purposes:
101 *
102 * 1. Disable preemption, in order to minimize the period of time
103 * in which the hwspinlock is taken. This is important in order
104 * to minimize the possible polling on the hardware interconnect
105 * by a remote user of this lock.
106 * 2. Make the hwspinlock SMP-safe (so we can take it from
107 * additional contexts on the local host).
108 * 3. Ensure that in_atomic/might_sleep checks catch potential
109 * problems with hwspinlock usage (e.g. scheduler checks like
110 * 'scheduling while atomic' etc.)
111 */
112 switch (mode) {
113 case HWLOCK_IRQSTATE:
114 ret = spin_trylock_irqsave(&hwlock->lock, *flags);
115 break;
116 case HWLOCK_IRQ:
117 ret = spin_trylock_irq(&hwlock->lock);
118 break;
119 case HWLOCK_RAW:
120 case HWLOCK_IN_ATOMIC:
121 ret = 1;
122 break;
123 default:
124 ret = spin_trylock(&hwlock->lock);
125 break;
126 }
127
128 /* is lock already taken by another context on the local cpu ? */
129 if (!ret)
130 return -EBUSY;
131
132 /* try to take the hwspinlock device */
133 ret = hwlock->bank->ops->trylock(hwlock);
134
135 /* if hwlock is already taken, undo spin_trylock_* and exit */
136 if (!ret) {
137 switch (mode) {
138 case HWLOCK_IRQSTATE:
139 spin_unlock_irqrestore(&hwlock->lock, *flags);
140 break;
141 case HWLOCK_IRQ:
142 spin_unlock_irq(&hwlock->lock);
143 break;
144 case HWLOCK_RAW:
145 case HWLOCK_IN_ATOMIC:
146 /* Nothing to do */
147 break;
148 default:
149 spin_unlock(&hwlock->lock);
150 break;
151 }
152
153 return -EBUSY;
154 }
155
156 /*
157 * We can be sure the other core's memory operations
158 * are observable to us only _after_ we successfully take
159 * the hwspinlock, and we must make sure that subsequent memory
160 * operations (both reads and writes) will not be reordered before
161 * we actually took the hwspinlock.
162 *
163 * Note: the implicit memory barrier of the spinlock above is too
164 * early, so we need this additional explicit memory barrier.
165 */
166 mb();
167
168 return 0;
169}
170EXPORT_SYMBOL_GPL(__hwspin_trylock);
171
172/**
173 * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit
174 * @hwlock: the hwspinlock to be locked
175 * @to: timeout value in msecs
176 * @mode: mode which controls whether local interrupts are disabled or not
177 * @flags: a pointer to where the caller's interrupt state will be saved at (if
178 * requested)
179 *
180 * This function locks the given @hwlock. If the @hwlock
181 * is already taken, the function will busy loop waiting for it to
182 * be released, but give up after @timeout msecs have elapsed.
183 *
184 * Caution: If the mode is HWLOCK_RAW, that means user must protect the routine
185 * of getting hardware lock with mutex or spinlock. Since in some scenarios,
186 * user need some time-consuming or sleepable operations under the hardware
187 * lock, they need one sleepable lock (like mutex) to protect the operations.
188 *
189 * If the mode is HWLOCK_IN_ATOMIC (called from an atomic context) the timeout
190 * is handled with busy-waiting delays, hence shall not exceed few msecs.
191 *
192 * If the mode is neither HWLOCK_IN_ATOMIC nor HWLOCK_RAW, upon a successful
193 * return from this function, preemption (and possibly interrupts) is disabled,
194 * so the caller must not sleep, and is advised to release the hwspinlock as
195 * soon as possible. This is required in order to minimize remote cores polling
196 * on the hardware interconnect.
197 *
198 * The user decides whether local interrupts are disabled or not, and if yes,
199 * whether he wants their previous state to be saved. It is up to the user
200 * to choose the appropriate @mode of operation, exactly the same way users
201 * should decide between spin_lock, spin_lock_irq and spin_lock_irqsave.
202 *
203 * Returns: %0 when the @hwlock was successfully taken, and an appropriate
204 * error code otherwise (most notably -ETIMEDOUT if the @hwlock is still
205 * busy after @timeout msecs).
206 *
207 * The function will never sleep.
208 */
209int __hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned int to,
210 int mode, unsigned long *flags)
211{
212 int ret;
213 unsigned long expire, atomic_delay = 0;
214
215 expire = msecs_to_jiffies(to) + jiffies;
216
217 for (;;) {
218 /* Try to take the hwspinlock */
219 ret = __hwspin_trylock(hwlock, mode, flags);
220 if (ret != -EBUSY)
221 break;
222
223 /*
224 * The lock is already taken, let's check if the user wants
225 * us to try again
226 */
227 if (mode == HWLOCK_IN_ATOMIC) {
228 udelay(HWSPINLOCK_RETRY_DELAY_US);
229 atomic_delay += HWSPINLOCK_RETRY_DELAY_US;
230 if (atomic_delay > to * 1000)
231 return -ETIMEDOUT;
232 } else {
233 if (time_is_before_eq_jiffies(expire))
234 return -ETIMEDOUT;
235 }
236
237 /*
238 * Allow platform-specific relax handlers to prevent
239 * hogging the interconnect (no sleeping, though)
240 */
241 if (hwlock->bank->ops->relax)
242 hwlock->bank->ops->relax(hwlock);
243 }
244
245 return ret;
246}
247EXPORT_SYMBOL_GPL(__hwspin_lock_timeout);
248
249/**
250 * __hwspin_unlock() - unlock a specific hwspinlock
251 * @hwlock: a previously-acquired hwspinlock which we want to unlock
252 * @mode: controls whether local interrupts needs to be restored or not
253 * @flags: previous caller's interrupt state to restore (if requested)
254 *
255 * This function will unlock a specific hwspinlock, enable preemption and
256 * (possibly) enable interrupts or restore their previous state.
257 * @hwlock must be already locked before calling this function: it is a bug
258 * to call unlock on a @hwlock that is already unlocked.
259 *
260 * The user decides whether local interrupts should be enabled or not, and
261 * if yes, whether he wants their previous state to be restored. It is up
262 * to the user to choose the appropriate @mode of operation, exactly the
263 * same way users decide between spin_unlock, spin_unlock_irq and
264 * spin_unlock_irqrestore.
265 *
266 * The function will never sleep.
267 */
268void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
269{
270 if (WARN_ON(!hwlock || (!flags && mode == HWLOCK_IRQSTATE)))
271 return;
272
273 /*
274 * We must make sure that memory operations (both reads and writes),
275 * done before unlocking the hwspinlock, will not be reordered
276 * after the lock is released.
277 *
278 * That's the purpose of this explicit memory barrier.
279 *
280 * Note: the memory barrier induced by the spin_unlock below is too
281 * late; the other core is going to access memory soon after it will
282 * take the hwspinlock, and by then we want to be sure our memory
283 * operations are already observable.
284 */
285 mb();
286
287 hwlock->bank->ops->unlock(hwlock);
288
289 /* Undo the spin_trylock{_irq, _irqsave} called while locking */
290 switch (mode) {
291 case HWLOCK_IRQSTATE:
292 spin_unlock_irqrestore(&hwlock->lock, *flags);
293 break;
294 case HWLOCK_IRQ:
295 spin_unlock_irq(&hwlock->lock);
296 break;
297 case HWLOCK_RAW:
298 case HWLOCK_IN_ATOMIC:
299 /* Nothing to do */
300 break;
301 default:
302 spin_unlock(&hwlock->lock);
303 break;
304 }
305}
306EXPORT_SYMBOL_GPL(__hwspin_unlock);
307
308/**
309 * of_hwspin_lock_simple_xlate - translate hwlock_spec to return a lock id
310 * @hwlock_spec: hwlock specifier as found in the device tree
311 *
312 * This is a simple translation function, suitable for hwspinlock platform
313 * drivers that only has a lock specifier length of 1.
314 *
315 * Returns: a relative index of the lock within a specified bank on success,
316 * or -EINVAL on invalid specifier cell count.
317 */
318static inline int
319of_hwspin_lock_simple_xlate(const struct of_phandle_args *hwlock_spec)
320{
321 if (WARN_ON(hwlock_spec->args_count != 1))
322 return -EINVAL;
323
324 return hwlock_spec->args[0];
325}
326
327/**
328 * of_hwspin_lock_get_id() - get lock id for an OF phandle-based specific lock
329 * @np: device node from which to request the specific hwlock
330 * @index: index of the hwlock in the list of values
331 *
332 * This function provides a means for DT users of the hwspinlock module to
333 * get the global lock id of a specific hwspinlock using the phandle of the
334 * hwspinlock device, so that it can be requested using the normal
335 * hwspin_lock_request_specific() API.
336 *
337 * Returns: the global lock id number on success, -EPROBE_DEFER if the
338 * hwspinlock device is not yet registered, -EINVAL on invalid args
339 * specifier value or an appropriate error as returned from the OF parsing
340 * of the DT client node.
341 */
342int of_hwspin_lock_get_id(struct device_node *np, int index)
343{
344 struct of_phandle_args args;
345 struct hwspinlock *hwlock;
346 struct radix_tree_iter iter;
347 void **slot;
348 int id;
349 int ret;
350
351 ret = of_parse_phandle_with_args(np, "hwlocks", "#hwlock-cells", index,
352 &args);
353 if (ret)
354 return ret;
355
356 if (!of_device_is_available(args.np)) {
357 ret = -ENOENT;
358 goto out;
359 }
360
361 /* Find the hwspinlock device: we need its base_id */
362 ret = -EPROBE_DEFER;
363 rcu_read_lock();
364 radix_tree_for_each_slot(slot, &hwspinlock_tree, &iter, 0) {
365 hwlock = radix_tree_deref_slot(slot);
366 if (unlikely(!hwlock))
367 continue;
368 if (radix_tree_deref_retry(hwlock)) {
369 slot = radix_tree_iter_retry(&iter);
370 continue;
371 }
372
373 if (device_match_of_node(hwlock->bank->dev, args.np)) {
374 ret = 0;
375 break;
376 }
377 }
378 rcu_read_unlock();
379 if (ret < 0)
380 goto out;
381
382 id = of_hwspin_lock_simple_xlate(&args);
383 if (id < 0 || id >= hwlock->bank->num_locks) {
384 ret = -EINVAL;
385 goto out;
386 }
387 id += hwlock->bank->base_id;
388
389out:
390 of_node_put(args.np);
391 return ret ? ret : id;
392}
393EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id);
394
395/**
396 * of_hwspin_lock_get_id_byname() - get lock id for an specified hwlock name
397 * @np: device node from which to request the specific hwlock
398 * @name: hwlock name
399 *
400 * This function provides a means for DT users of the hwspinlock module to
401 * get the global lock id of a specific hwspinlock using the specified name of
402 * the hwspinlock device, so that it can be requested using the normal
403 * hwspin_lock_request_specific() API.
404 *
405 * Returns: the global lock id number on success, -EPROBE_DEFER if the
406 * hwspinlock device is not yet registered, -EINVAL on invalid args
407 * specifier value or an appropriate error as returned from the OF parsing
408 * of the DT client node.
409 */
410int of_hwspin_lock_get_id_byname(struct device_node *np, const char *name)
411{
412 int index;
413
414 if (!name)
415 return -EINVAL;
416
417 index = of_property_match_string(np, "hwlock-names", name);
418 if (index < 0)
419 return index;
420
421 return of_hwspin_lock_get_id(np, index);
422}
423EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id_byname);
424
425static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id)
426{
427 struct hwspinlock *tmp;
428 int ret;
429
430 mutex_lock(&hwspinlock_tree_lock);
431
432 ret = radix_tree_insert(&hwspinlock_tree, id, hwlock);
433 if (ret) {
434 if (ret == -EEXIST)
435 pr_err("hwspinlock id %d already exists!\n", id);
436 goto out;
437 }
438
439 /* mark this hwspinlock as available */
440 tmp = radix_tree_tag_set(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
441
442 /* self-sanity check which should never fail */
443 WARN_ON(tmp != hwlock);
444
445out:
446 mutex_unlock(&hwspinlock_tree_lock);
447 return 0;
448}
449
450static struct hwspinlock *hwspin_lock_unregister_single(unsigned int id)
451{
452 struct hwspinlock *hwlock = NULL;
453 int ret;
454
455 mutex_lock(&hwspinlock_tree_lock);
456
457 /* make sure the hwspinlock is not in use (tag is set) */
458 ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
459 if (ret == 0) {
460 pr_err("hwspinlock %d still in use (or not present)\n", id);
461 goto out;
462 }
463
464 hwlock = radix_tree_delete(&hwspinlock_tree, id);
465 if (!hwlock) {
466 pr_err("failed to delete hwspinlock %d\n", id);
467 goto out;
468 }
469
470out:
471 mutex_unlock(&hwspinlock_tree_lock);
472 return hwlock;
473}
474
475/**
476 * hwspin_lock_register() - register a new hw spinlock device
477 * @bank: the hwspinlock device, which usually provides numerous hw locks
478 * @dev: the backing device
479 * @ops: hwspinlock handlers for this device
480 * @base_id: id of the first hardware spinlock in this bank
481 * @num_locks: number of hwspinlocks provided by this device
482 *
483 * This function should be called from the underlying platform-specific
484 * implementation, to register a new hwspinlock device instance.
485 *
486 * Should be called from a process context (might sleep)
487 *
488 * Returns: %0 on success, or an appropriate error code on failure
489 */
490int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
491 const struct hwspinlock_ops *ops, int base_id, int num_locks)
492{
493 struct hwspinlock *hwlock;
494 int ret = 0, i;
495
496 if (!bank || !ops || !dev || !num_locks || !ops->trylock ||
497 !ops->unlock) {
498 pr_err("invalid parameters\n");
499 return -EINVAL;
500 }
501
502 bank->dev = dev;
503 bank->ops = ops;
504 bank->base_id = base_id;
505 bank->num_locks = num_locks;
506
507 for (i = 0; i < num_locks; i++) {
508 hwlock = &bank->lock[i];
509
510 spin_lock_init(&hwlock->lock);
511 hwlock->bank = bank;
512
513 ret = hwspin_lock_register_single(hwlock, base_id + i);
514 if (ret)
515 goto reg_failed;
516 }
517
518 return 0;
519
520reg_failed:
521 while (--i >= 0)
522 hwspin_lock_unregister_single(base_id + i);
523 return ret;
524}
525EXPORT_SYMBOL_GPL(hwspin_lock_register);
526
527/**
528 * hwspin_lock_unregister() - unregister an hw spinlock device
529 * @bank: the hwspinlock device, which usually provides numerous hw locks
530 *
531 * This function should be called from the underlying platform-specific
532 * implementation, to unregister an existing (and unused) hwspinlock.
533 *
534 * Should be called from a process context (might sleep)
535 *
536 * Returns: %0 on success, or an appropriate error code on failure
537 */
538int hwspin_lock_unregister(struct hwspinlock_device *bank)
539{
540 struct hwspinlock *hwlock, *tmp;
541 int i;
542
543 for (i = 0; i < bank->num_locks; i++) {
544 hwlock = &bank->lock[i];
545
546 tmp = hwspin_lock_unregister_single(bank->base_id + i);
547 if (!tmp)
548 return -EBUSY;
549
550 /* self-sanity check that should never fail */
551 WARN_ON(tmp != hwlock);
552 }
553
554 return 0;
555}
556EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
557
558static void devm_hwspin_lock_unreg(struct device *dev, void *res)
559{
560 hwspin_lock_unregister(*(struct hwspinlock_device **)res);
561}
562
563static int devm_hwspin_lock_device_match(struct device *dev, void *res,
564 void *data)
565{
566 struct hwspinlock_device **bank = res;
567
568 if (WARN_ON(!bank || !*bank))
569 return 0;
570
571 return *bank == data;
572}
573
574/**
575 * devm_hwspin_lock_unregister() - unregister an hw spinlock device for
576 * a managed device
577 * @dev: the backing device
578 * @bank: the hwspinlock device, which usually provides numerous hw locks
579 *
580 * This function should be called from the underlying platform-specific
581 * implementation, to unregister an existing (and unused) hwspinlock.
582 *
583 * Should be called from a process context (might sleep)
584 *
585 * Returns: %0 on success, or an appropriate error code on failure
586 */
587int devm_hwspin_lock_unregister(struct device *dev,
588 struct hwspinlock_device *bank)
589{
590 int ret;
591
592 ret = devres_release(dev, devm_hwspin_lock_unreg,
593 devm_hwspin_lock_device_match, bank);
594 WARN_ON(ret);
595
596 return ret;
597}
598EXPORT_SYMBOL_GPL(devm_hwspin_lock_unregister);
599
600/**
601 * devm_hwspin_lock_register() - register a new hw spinlock device for
602 * a managed device
603 * @dev: the backing device
604 * @bank: the hwspinlock device, which usually provides numerous hw locks
605 * @ops: hwspinlock handlers for this device
606 * @base_id: id of the first hardware spinlock in this bank
607 * @num_locks: number of hwspinlocks provided by this device
608 *
609 * This function should be called from the underlying platform-specific
610 * implementation, to register a new hwspinlock device instance.
611 *
612 * Should be called from a process context (might sleep)
613 *
614 * Returns: %0 on success, or an appropriate error code on failure
615 */
616int devm_hwspin_lock_register(struct device *dev,
617 struct hwspinlock_device *bank,
618 const struct hwspinlock_ops *ops,
619 int base_id, int num_locks)
620{
621 struct hwspinlock_device **ptr;
622 int ret;
623
624 ptr = devres_alloc(devm_hwspin_lock_unreg, sizeof(*ptr), GFP_KERNEL);
625 if (!ptr)
626 return -ENOMEM;
627
628 ret = hwspin_lock_register(bank, dev, ops, base_id, num_locks);
629 if (!ret) {
630 *ptr = bank;
631 devres_add(dev, ptr);
632 } else {
633 devres_free(ptr);
634 }
635
636 return ret;
637}
638EXPORT_SYMBOL_GPL(devm_hwspin_lock_register);
639
640/**
641 * __hwspin_lock_request() - tag an hwspinlock as used and power it up
642 * @hwlock: the target hwspinlock
643 *
644 * This is an internal function that prepares an hwspinlock instance
645 * before it is given to the user. The function assumes that
646 * hwspinlock_tree_lock is taken.
647 *
648 * Returns: %0 or positive to indicate success, and a negative value to
649 * indicate an error (with the appropriate error code)
650 */
651static int __hwspin_lock_request(struct hwspinlock *hwlock)
652{
653 struct device *dev = hwlock->bank->dev;
654 struct hwspinlock *tmp;
655 int ret;
656
657 /* prevent underlying implementation from being removed */
658 if (!try_module_get(dev->driver->owner)) {
659 dev_err(dev, "%s: can't get owner\n", __func__);
660 return -EINVAL;
661 }
662
663 /* notify PM core that power is now needed */
664 ret = pm_runtime_get_sync(dev);
665 if (ret < 0 && ret != -EACCES) {
666 dev_err(dev, "%s: can't power on device\n", __func__);
667 pm_runtime_put_noidle(dev);
668 module_put(dev->driver->owner);
669 return ret;
670 }
671
672 ret = 0;
673
674 /* mark hwspinlock as used, should not fail */
675 tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock),
676 HWSPINLOCK_UNUSED);
677
678 /* self-sanity check that should never fail */
679 WARN_ON(tmp != hwlock);
680
681 return ret;
682}
683
684/**
685 * hwspin_lock_get_id() - retrieve id number of a given hwspinlock
686 * @hwlock: a valid hwspinlock instance
687 *
688 * Returns: the id number of a given @hwlock, or -EINVAL if @hwlock is invalid.
689 */
690int hwspin_lock_get_id(struct hwspinlock *hwlock)
691{
692 if (!hwlock) {
693 pr_err("invalid hwlock\n");
694 return -EINVAL;
695 }
696
697 return hwlock_to_id(hwlock);
698}
699EXPORT_SYMBOL_GPL(hwspin_lock_get_id);
700
701/**
702 * hwspin_lock_request() - request an hwspinlock
703 *
704 * This function should be called by users of the hwspinlock device,
705 * in order to dynamically assign them an unused hwspinlock.
706 * Usually the user of this lock will then have to communicate the lock's id
707 * to the remote core before it can be used for synchronization (to get the
708 * id of a given hwlock, use hwspin_lock_get_id()).
709 *
710 * Should be called from a process context (might sleep)
711 *
712 * Returns: the address of the assigned hwspinlock, or %NULL on error
713 */
714struct hwspinlock *hwspin_lock_request(void)
715{
716 struct hwspinlock *hwlock;
717 int ret;
718
719 mutex_lock(&hwspinlock_tree_lock);
720
721 /* look for an unused lock */
722 ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
723 0, 1, HWSPINLOCK_UNUSED);
724 if (ret == 0) {
725 pr_warn("a free hwspinlock is not available\n");
726 hwlock = NULL;
727 goto out;
728 }
729
730 /* sanity check that should never fail */
731 WARN_ON(ret > 1);
732
733 /* mark as used and power up */
734 ret = __hwspin_lock_request(hwlock);
735 if (ret < 0)
736 hwlock = NULL;
737
738out:
739 mutex_unlock(&hwspinlock_tree_lock);
740 return hwlock;
741}
742EXPORT_SYMBOL_GPL(hwspin_lock_request);
743
744/**
745 * hwspin_lock_request_specific() - request for a specific hwspinlock
746 * @id: index of the specific hwspinlock that is requested
747 *
748 * This function should be called by users of the hwspinlock module,
749 * in order to assign them a specific hwspinlock.
750 * Usually early board code will be calling this function in order to
751 * reserve specific hwspinlock ids for predefined purposes.
752 *
753 * Should be called from a process context (might sleep)
754 *
755 * Returns: the address of the assigned hwspinlock, or %NULL on error
756 */
757struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
758{
759 struct hwspinlock *hwlock;
760 int ret;
761
762 mutex_lock(&hwspinlock_tree_lock);
763
764 /* make sure this hwspinlock exists */
765 hwlock = radix_tree_lookup(&hwspinlock_tree, id);
766 if (!hwlock) {
767 pr_warn("hwspinlock %u does not exist\n", id);
768 goto out;
769 }
770
771 /* sanity check (this shouldn't happen) */
772 WARN_ON(hwlock_to_id(hwlock) != id);
773
774 /* make sure this hwspinlock is unused */
775 ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
776 if (ret == 0) {
777 pr_warn("hwspinlock %u is already in use\n", id);
778 hwlock = NULL;
779 goto out;
780 }
781
782 /* mark as used and power up */
783 ret = __hwspin_lock_request(hwlock);
784 if (ret < 0)
785 hwlock = NULL;
786
787out:
788 mutex_unlock(&hwspinlock_tree_lock);
789 return hwlock;
790}
791EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
792
793/**
794 * hwspin_lock_free() - free a specific hwspinlock
795 * @hwlock: the specific hwspinlock to free
796 *
797 * This function mark @hwlock as free again.
798 * Should only be called with an @hwlock that was retrieved from
799 * an earlier call to hwspin_lock_request{_specific}.
800 *
801 * Should be called from a process context (might sleep)
802 *
803 * Returns: %0 on success, or an appropriate error code on failure
804 */
805int hwspin_lock_free(struct hwspinlock *hwlock)
806{
807 struct device *dev;
808 struct hwspinlock *tmp;
809 int ret;
810
811 if (!hwlock) {
812 pr_err("invalid hwlock\n");
813 return -EINVAL;
814 }
815
816 dev = hwlock->bank->dev;
817 mutex_lock(&hwspinlock_tree_lock);
818
819 /* make sure the hwspinlock is used */
820 ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock),
821 HWSPINLOCK_UNUSED);
822 if (ret == 1) {
823 dev_err(dev, "%s: hwlock is already free\n", __func__);
824 dump_stack();
825 ret = -EINVAL;
826 goto out;
827 }
828
829 /* notify the underlying device that power is not needed */
830 pm_runtime_put(dev);
831
832 /* mark this hwspinlock as available */
833 tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock),
834 HWSPINLOCK_UNUSED);
835
836 /* sanity check (this shouldn't happen) */
837 WARN_ON(tmp != hwlock);
838
839 module_put(dev->driver->owner);
840
841out:
842 mutex_unlock(&hwspinlock_tree_lock);
843 return ret;
844}
845EXPORT_SYMBOL_GPL(hwspin_lock_free);
846
847static int devm_hwspin_lock_match(struct device *dev, void *res, void *data)
848{
849 struct hwspinlock **hwlock = res;
850
851 if (WARN_ON(!hwlock || !*hwlock))
852 return 0;
853
854 return *hwlock == data;
855}
856
857static void devm_hwspin_lock_release(struct device *dev, void *res)
858{
859 hwspin_lock_free(*(struct hwspinlock **)res);
860}
861
862/**
863 * devm_hwspin_lock_free() - free a specific hwspinlock for a managed device
864 * @dev: the device to free the specific hwspinlock
865 * @hwlock: the specific hwspinlock to free
866 *
867 * This function mark @hwlock as free again.
868 * Should only be called with an @hwlock that was retrieved from
869 * an earlier call to hwspin_lock_request{_specific}.
870 *
871 * Should be called from a process context (might sleep)
872 *
873 * Returns: %0 on success, or an appropriate error code on failure
874 */
875int devm_hwspin_lock_free(struct device *dev, struct hwspinlock *hwlock)
876{
877 int ret;
878
879 ret = devres_release(dev, devm_hwspin_lock_release,
880 devm_hwspin_lock_match, hwlock);
881 WARN_ON(ret);
882
883 return ret;
884}
885EXPORT_SYMBOL_GPL(devm_hwspin_lock_free);
886
887/**
888 * devm_hwspin_lock_request() - request an hwspinlock for a managed device
889 * @dev: the device to request an hwspinlock
890 *
891 * This function should be called by users of the hwspinlock device,
892 * in order to dynamically assign them an unused hwspinlock.
893 * Usually the user of this lock will then have to communicate the lock's id
894 * to the remote core before it can be used for synchronization (to get the
895 * id of a given hwlock, use hwspin_lock_get_id()).
896 *
897 * Should be called from a process context (might sleep)
898 *
899 * Returns: the address of the assigned hwspinlock, or %NULL on error
900 */
901struct hwspinlock *devm_hwspin_lock_request(struct device *dev)
902{
903 struct hwspinlock **ptr, *hwlock;
904
905 ptr = devres_alloc(devm_hwspin_lock_release, sizeof(*ptr), GFP_KERNEL);
906 if (!ptr)
907 return NULL;
908
909 hwlock = hwspin_lock_request();
910 if (hwlock) {
911 *ptr = hwlock;
912 devres_add(dev, ptr);
913 } else {
914 devres_free(ptr);
915 }
916
917 return hwlock;
918}
919EXPORT_SYMBOL_GPL(devm_hwspin_lock_request);
920
921/**
922 * devm_hwspin_lock_request_specific() - request for a specific hwspinlock for
923 * a managed device
924 * @dev: the device to request the specific hwspinlock
925 * @id: index of the specific hwspinlock that is requested
926 *
927 * This function should be called by users of the hwspinlock module,
928 * in order to assign them a specific hwspinlock.
929 * Usually early board code will be calling this function in order to
930 * reserve specific hwspinlock ids for predefined purposes.
931 *
932 * Should be called from a process context (might sleep)
933 *
934 * Returns: the address of the assigned hwspinlock, or %NULL on error
935 */
936struct hwspinlock *devm_hwspin_lock_request_specific(struct device *dev,
937 unsigned int id)
938{
939 struct hwspinlock **ptr, *hwlock;
940
941 ptr = devres_alloc(devm_hwspin_lock_release, sizeof(*ptr), GFP_KERNEL);
942 if (!ptr)
943 return NULL;
944
945 hwlock = hwspin_lock_request_specific(id);
946 if (hwlock) {
947 *ptr = hwlock;
948 devres_add(dev, ptr);
949 } else {
950 devres_free(ptr);
951 }
952
953 return hwlock;
954}
955EXPORT_SYMBOL_GPL(devm_hwspin_lock_request_specific);
956
957MODULE_DESCRIPTION("Hardware spinlock interface");
958MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
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 */
50static 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 */
57static 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 */
91int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
92{
93 int ret;
94
95 if (WARN_ON(!hwlock || (!flags && mode == HWLOCK_IRQSTATE)))
96 return -EINVAL;
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}
169EXPORT_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 */
206int __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}
244EXPORT_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 */
265void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
266{
267 if (WARN_ON(!hwlock || (!flags && mode == HWLOCK_IRQSTATE)))
268 return;
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}
303EXPORT_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 */
316static inline int
317of_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 */
339int 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
386out:
387 of_node_put(args.np);
388 return ret ? ret : id;
389}
390EXPORT_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 */
406int 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}
419EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id_byname);
420
421static 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
441out:
442 mutex_unlock(&hwspinlock_tree_lock);
443 return 0;
444}
445
446static 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
466out:
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 */
486int 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
516reg_failed:
517 while (--i >= 0)
518 hwspin_lock_unregister_single(base_id + i);
519 return ret;
520}
521EXPORT_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 */
534int 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}
552EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
553
554static void devm_hwspin_lock_unreg(struct device *dev, void *res)
555{
556 hwspin_lock_unregister(*(struct hwspinlock_device **)res);
557}
558
559static 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 */
583int 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}
594EXPORT_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 */
612int 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}
634EXPORT_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 */
646static 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 && ret != -EACCES) {
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 ret = 0;
668
669 /* mark hwspinlock as used, should not fail */
670 tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock),
671 HWSPINLOCK_UNUSED);
672
673 /* self-sanity check that should never fail */
674 WARN_ON(tmp != hwlock);
675
676 return ret;
677}
678
679/**
680 * hwspin_lock_get_id() - retrieve id number of a given hwspinlock
681 * @hwlock: a valid hwspinlock instance
682 *
683 * Returns the id number of a given @hwlock, or -EINVAL if @hwlock is invalid.
684 */
685int hwspin_lock_get_id(struct hwspinlock *hwlock)
686{
687 if (!hwlock) {
688 pr_err("invalid hwlock\n");
689 return -EINVAL;
690 }
691
692 return hwlock_to_id(hwlock);
693}
694EXPORT_SYMBOL_GPL(hwspin_lock_get_id);
695
696/**
697 * hwspin_lock_request() - request an hwspinlock
698 *
699 * This function should be called by users of the hwspinlock device,
700 * in order to dynamically assign them an unused hwspinlock.
701 * Usually the user of this lock will then have to communicate the lock's id
702 * to the remote core before it can be used for synchronization (to get the
703 * id of a given hwlock, use hwspin_lock_get_id()).
704 *
705 * Should be called from a process context (might sleep)
706 *
707 * Returns the address of the assigned hwspinlock, or NULL on error
708 */
709struct hwspinlock *hwspin_lock_request(void)
710{
711 struct hwspinlock *hwlock;
712 int ret;
713
714 mutex_lock(&hwspinlock_tree_lock);
715
716 /* look for an unused lock */
717 ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
718 0, 1, HWSPINLOCK_UNUSED);
719 if (ret == 0) {
720 pr_warn("a free hwspinlock is not available\n");
721 hwlock = NULL;
722 goto out;
723 }
724
725 /* sanity check that should never fail */
726 WARN_ON(ret > 1);
727
728 /* mark as used and power up */
729 ret = __hwspin_lock_request(hwlock);
730 if (ret < 0)
731 hwlock = NULL;
732
733out:
734 mutex_unlock(&hwspinlock_tree_lock);
735 return hwlock;
736}
737EXPORT_SYMBOL_GPL(hwspin_lock_request);
738
739/**
740 * hwspin_lock_request_specific() - request for a specific hwspinlock
741 * @id: index of the specific hwspinlock that is requested
742 *
743 * This function should be called by users of the hwspinlock module,
744 * in order to assign them a specific hwspinlock.
745 * Usually early board code will be calling this function in order to
746 * reserve specific hwspinlock ids for predefined purposes.
747 *
748 * Should be called from a process context (might sleep)
749 *
750 * Returns the address of the assigned hwspinlock, or NULL on error
751 */
752struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
753{
754 struct hwspinlock *hwlock;
755 int ret;
756
757 mutex_lock(&hwspinlock_tree_lock);
758
759 /* make sure this hwspinlock exists */
760 hwlock = radix_tree_lookup(&hwspinlock_tree, id);
761 if (!hwlock) {
762 pr_warn("hwspinlock %u does not exist\n", id);
763 goto out;
764 }
765
766 /* sanity check (this shouldn't happen) */
767 WARN_ON(hwlock_to_id(hwlock) != id);
768
769 /* make sure this hwspinlock is unused */
770 ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
771 if (ret == 0) {
772 pr_warn("hwspinlock %u is already in use\n", id);
773 hwlock = NULL;
774 goto out;
775 }
776
777 /* mark as used and power up */
778 ret = __hwspin_lock_request(hwlock);
779 if (ret < 0)
780 hwlock = NULL;
781
782out:
783 mutex_unlock(&hwspinlock_tree_lock);
784 return hwlock;
785}
786EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
787
788/**
789 * hwspin_lock_free() - free a specific hwspinlock
790 * @hwlock: the specific hwspinlock to free
791 *
792 * This function mark @hwlock as free again.
793 * Should only be called with an @hwlock that was retrieved from
794 * an earlier call to hwspin_lock_request{_specific}.
795 *
796 * Should be called from a process context (might sleep)
797 *
798 * Returns 0 on success, or an appropriate error code on failure
799 */
800int hwspin_lock_free(struct hwspinlock *hwlock)
801{
802 struct device *dev;
803 struct hwspinlock *tmp;
804 int ret;
805
806 if (!hwlock) {
807 pr_err("invalid hwlock\n");
808 return -EINVAL;
809 }
810
811 dev = hwlock->bank->dev;
812 mutex_lock(&hwspinlock_tree_lock);
813
814 /* make sure the hwspinlock is used */
815 ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock),
816 HWSPINLOCK_UNUSED);
817 if (ret == 1) {
818 dev_err(dev, "%s: hwlock is already free\n", __func__);
819 dump_stack();
820 ret = -EINVAL;
821 goto out;
822 }
823
824 /* notify the underlying device that power is not needed */
825 pm_runtime_put(dev);
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
836out:
837 mutex_unlock(&hwspinlock_tree_lock);
838 return ret;
839}
840EXPORT_SYMBOL_GPL(hwspin_lock_free);
841
842static 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
852static 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 */
870int 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}
880EXPORT_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 */
896struct 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}
914EXPORT_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 */
931struct 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}
950EXPORT_SYMBOL_GPL(devm_hwspin_lock_request_specific);
951
952MODULE_LICENSE("GPL v2");
953MODULE_DESCRIPTION("Hardware spinlock interface");
954MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");