1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Mailbox: Common code for Mailbox controllers and users
4  *
5  * Copyright (C) 2013-2014 Linaro Ltd.
6  * Author: Jassi Brar <jassisinghbrar@gmail.com>
7  */
8 
9 #include <linux/interrupt.h>
10 #include <linux/spinlock.h>
11 #include <linux/mutex.h>
12 #include <linux/delay.h>
13 #include <linux/slab.h>
14 #include <linux/err.h>
15 #include <linux/module.h>
16 #include <linux/device.h>
17 #include <linux/bitops.h>
18 #include <linux/mailbox_client.h>
19 #include <linux/mailbox_controller.h>
20 #include <linux/of.h>
21 
22 #include "mailbox.h"
23 
24 static LIST_HEAD(mbox_cons);
25 static DEFINE_MUTEX(con_mutex);
26 
add_to_rbuf(struct mbox_chan * chan,void * mssg)27 static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
28 {
29 	int idx;
30 	unsigned long flags;
31 
32 	spin_lock_irqsave(&chan->lock, flags);
33 
34 	/* See if there is any space left */
35 	if (chan->msg_count == MBOX_TX_QUEUE_LEN) {
36 		spin_unlock_irqrestore(&chan->lock, flags);
37 		return -ENOBUFS;
38 	}
39 
40 	idx = chan->msg_free;
41 	chan->msg_data[idx] = mssg;
42 	chan->msg_count++;
43 
44 	if (idx == MBOX_TX_QUEUE_LEN - 1)
45 		chan->msg_free = 0;
46 	else
47 		chan->msg_free++;
48 
49 	spin_unlock_irqrestore(&chan->lock, flags);
50 
51 	return idx;
52 }
53 
msg_submit(struct mbox_chan * chan)54 static void msg_submit(struct mbox_chan *chan)
55 {
56 	unsigned count, idx;
57 	unsigned long flags;
58 	void *data;
59 	int err = -EBUSY;
60 
61 	spin_lock_irqsave(&chan->lock, flags);
62 
63 	if (!chan->msg_count || chan->active_req)
64 		goto exit;
65 
66 	count = chan->msg_count;
67 	idx = chan->msg_free;
68 	if (idx >= count)
69 		idx -= count;
70 	else
71 		idx += MBOX_TX_QUEUE_LEN - count;
72 
73 	data = chan->msg_data[idx];
74 
75 	if (chan->cl->tx_prepare)
76 		chan->cl->tx_prepare(chan->cl, data);
77 	/* Try to submit a message to the MBOX controller */
78 	err = chan->mbox->ops->send_data(chan, data);
79 	if (!err) {
80 		chan->active_req = data;
81 		chan->msg_count--;
82 	}
83 exit:
84 	spin_unlock_irqrestore(&chan->lock, flags);
85 
86 	if (!err && (chan->txdone_method & TXDONE_BY_POLL)) {
87 		/* kick start the timer immediately to avoid delays */
88 		spin_lock_irqsave(&chan->mbox->poll_hrt_lock, flags);
89 		hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
90 		spin_unlock_irqrestore(&chan->mbox->poll_hrt_lock, flags);
91 	}
92 }
93 
tx_tick(struct mbox_chan * chan,int r)94 static void tx_tick(struct mbox_chan *chan, int r)
95 {
96 	unsigned long flags;
97 	void *mssg;
98 
99 	spin_lock_irqsave(&chan->lock, flags);
100 	mssg = chan->active_req;
101 	chan->active_req = NULL;
102 	spin_unlock_irqrestore(&chan->lock, flags);
103 
104 	/* Submit next message */
105 	msg_submit(chan);
106 
107 	if (!mssg)
108 		return;
109 
110 	/* Notify the client */
111 	if (chan->cl->tx_done)
112 		chan->cl->tx_done(chan->cl, mssg, r);
113 
114 	if (r != -ETIME && chan->cl->tx_block)
115 		complete(&chan->tx_complete);
116 }
117 
txdone_hrtimer(struct hrtimer * hrtimer)118 static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
119 {
120 	struct mbox_controller *mbox =
121 		container_of(hrtimer, struct mbox_controller, poll_hrt);
122 	bool txdone, resched = false;
123 	int i;
124 	unsigned long flags;
125 
126 	for (i = 0; i < mbox->num_chans; i++) {
127 		struct mbox_chan *chan = &mbox->chans[i];
128 
129 		if (chan->active_req && chan->cl) {
130 			txdone = chan->mbox->ops->last_tx_done(chan);
131 			if (txdone)
132 				tx_tick(chan, 0);
133 			else
134 				resched = true;
135 		}
136 	}
137 
138 	if (resched) {
139 		spin_lock_irqsave(&mbox->poll_hrt_lock, flags);
140 		if (!hrtimer_is_queued(hrtimer))
141 			hrtimer_forward_now(hrtimer, ms_to_ktime(mbox->txpoll_period));
142 		spin_unlock_irqrestore(&mbox->poll_hrt_lock, flags);
143 
144 		return HRTIMER_RESTART;
145 	}
146 	return HRTIMER_NORESTART;
147 }
148 
149 /**
150  * mbox_chan_received_data - A way for controller driver to push data
151  *				received from remote to the upper layer.
152  * @chan: Pointer to the mailbox channel on which RX happened.
153  * @mssg: Client specific message typecasted as void *
154  *
155  * After startup and before shutdown any data received on the chan
156  * is passed on to the API via atomic mbox_chan_received_data().
157  * The controller should ACK the RX only after this call returns.
158  */
mbox_chan_received_data(struct mbox_chan * chan,void * mssg)159 void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
160 {
161 	/* No buffering the received data */
162 	if (chan->cl->rx_callback)
163 		chan->cl->rx_callback(chan->cl, mssg);
164 }
165 EXPORT_SYMBOL_GPL(mbox_chan_received_data);
166 
167 /**
168  * mbox_chan_txdone - A way for controller driver to notify the
169  *			framework that the last TX has completed.
170  * @chan: Pointer to the mailbox chan on which TX happened.
171  * @r: Status of last TX - OK or ERROR
172  *
173  * The controller that has IRQ for TX ACK calls this atomic API
174  * to tick the TX state machine. It works only if txdone_irq
175  * is set by the controller.
176  */
mbox_chan_txdone(struct mbox_chan * chan,int r)177 void mbox_chan_txdone(struct mbox_chan *chan, int r)
178 {
179 	if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
180 		dev_err(chan->mbox->dev,
181 		       "Controller can't run the TX ticker\n");
182 		return;
183 	}
184 
185 	tx_tick(chan, r);
186 }
187 EXPORT_SYMBOL_GPL(mbox_chan_txdone);
188 
189 /**
190  * mbox_client_txdone - The way for a client to run the TX state machine.
191  * @chan: Mailbox channel assigned to this client.
192  * @r: Success status of last transmission.
193  *
194  * The client/protocol had received some 'ACK' packet and it notifies
195  * the API that the last packet was sent successfully. This only works
196  * if the controller can't sense TX-Done.
197  */
mbox_client_txdone(struct mbox_chan * chan,int r)198 void mbox_client_txdone(struct mbox_chan *chan, int r)
199 {
200 	if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
201 		dev_err(chan->mbox->dev, "Client can't run the TX ticker\n");
202 		return;
203 	}
204 
205 	tx_tick(chan, r);
206 }
207 EXPORT_SYMBOL_GPL(mbox_client_txdone);
208 
209 /**
210  * mbox_client_peek_data - A way for client driver to pull data
211  *			received from remote by the controller.
212  * @chan: Mailbox channel assigned to this client.
213  *
214  * A poke to controller driver for any received data.
215  * The data is actually passed onto client via the
216  * mbox_chan_received_data()
217  * The call can be made from atomic context, so the controller's
218  * implementation of peek_data() must not sleep.
219  *
220  * Return: True, if controller has, and is going to push after this,
221  *          some data.
222  *         False, if controller doesn't have any data to be read.
223  */
mbox_client_peek_data(struct mbox_chan * chan)224 bool mbox_client_peek_data(struct mbox_chan *chan)
225 {
226 	if (chan->mbox->ops->peek_data)
227 		return chan->mbox->ops->peek_data(chan);
228 
229 	return false;
230 }
231 EXPORT_SYMBOL_GPL(mbox_client_peek_data);
232 
233 /**
234  * mbox_send_message -	For client to submit a message to be
235  *				sent to the remote.
236  * @chan: Mailbox channel assigned to this client.
237  * @mssg: Client specific message typecasted.
238  *
239  * For client to submit data to the controller destined for a remote
240  * processor. If the client had set 'tx_block', the call will return
241  * either when the remote receives the data or when 'tx_tout' millisecs
242  * run out.
243  *  In non-blocking mode, the requests are buffered by the API and a
244  * non-negative token is returned for each queued request. If the request
245  * is not queued, a negative token is returned. Upon failure or successful
246  * TX, the API calls 'tx_done' from atomic context, from which the client
247  * could submit yet another request.
248  * The pointer to message should be preserved until it is sent
249  * over the chan, i.e, tx_done() is made.
250  * This function could be called from atomic context as it simply
251  * queues the data and returns a token against the request.
252  *
253  * Return: Non-negative integer for successful submission (non-blocking mode)
254  *	or transmission over chan (blocking mode).
255  *	Negative value denotes failure.
256  */
mbox_send_message(struct mbox_chan * chan,void * mssg)257 int mbox_send_message(struct mbox_chan *chan, void *mssg)
258 {
259 	int t;
260 
261 	if (!chan || !chan->cl)
262 		return -EINVAL;
263 
264 	t = add_to_rbuf(chan, mssg);
265 	if (t < 0) {
266 		dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
267 		return t;
268 	}
269 
270 	msg_submit(chan);
271 
272 	if (chan->cl->tx_block) {
273 		unsigned long wait;
274 		int ret;
275 
276 		if (!chan->cl->tx_tout) /* wait forever */
277 			wait = msecs_to_jiffies(3600000);
278 		else
279 			wait = msecs_to_jiffies(chan->cl->tx_tout);
280 
281 		ret = wait_for_completion_timeout(&chan->tx_complete, wait);
282 		if (ret == 0) {
283 			t = -ETIME;
284 			tx_tick(chan, t);
285 		}
286 	}
287 
288 	return t;
289 }
290 EXPORT_SYMBOL_GPL(mbox_send_message);
291 
292 /**
293  * mbox_flush - flush a mailbox channel
294  * @chan: mailbox channel to flush
295  * @timeout: time, in milliseconds, to allow the flush operation to succeed
296  *
297  * Mailbox controllers that need to work in atomic context can implement the
298  * ->flush() callback to busy loop until a transmission has been completed.
299  * The implementation must call mbox_chan_txdone() upon success. Clients can
300  * call the mbox_flush() function at any time after mbox_send_message() to
301  * flush the transmission. After the function returns success, the mailbox
302  * transmission is guaranteed to have completed.
303  *
304  * Returns: 0 on success or a negative error code on failure.
305  */
mbox_flush(struct mbox_chan * chan,unsigned long timeout)306 int mbox_flush(struct mbox_chan *chan, unsigned long timeout)
307 {
308 	int ret;
309 
310 	if (!chan->mbox->ops->flush)
311 		return -ENOTSUPP;
312 
313 	ret = chan->mbox->ops->flush(chan, timeout);
314 	if (ret < 0)
315 		tx_tick(chan, ret);
316 
317 	return ret;
318 }
319 EXPORT_SYMBOL_GPL(mbox_flush);
320 
__mbox_bind_client(struct mbox_chan * chan,struct mbox_client * cl)321 static int __mbox_bind_client(struct mbox_chan *chan, struct mbox_client *cl)
322 {
323 	struct device *dev = cl->dev;
324 	unsigned long flags;
325 	int ret;
326 
327 	if (chan->cl || !try_module_get(chan->mbox->dev->driver->owner)) {
328 		dev_dbg(dev, "%s: mailbox not free\n", __func__);
329 		return -EBUSY;
330 	}
331 
332 	spin_lock_irqsave(&chan->lock, flags);
333 	chan->msg_free = 0;
334 	chan->msg_count = 0;
335 	chan->active_req = NULL;
336 	chan->cl = cl;
337 	init_completion(&chan->tx_complete);
338 
339 	if (chan->txdone_method	== TXDONE_BY_POLL && cl->knows_txdone)
340 		chan->txdone_method = TXDONE_BY_ACK;
341 
342 	spin_unlock_irqrestore(&chan->lock, flags);
343 
344 	if (chan->mbox->ops->startup) {
345 		ret = chan->mbox->ops->startup(chan);
346 
347 		if (ret) {
348 			dev_err(dev, "Unable to startup the chan (%d)\n", ret);
349 			mbox_free_channel(chan);
350 			return ret;
351 		}
352 	}
353 
354 	return 0;
355 }
356 
357 /**
358  * mbox_bind_client - Request a mailbox channel.
359  * @chan: The mailbox channel to bind the client to.
360  * @cl: Identity of the client requesting the channel.
361  *
362  * The Client specifies its requirements and capabilities while asking for
363  * a mailbox channel. It can't be called from atomic context.
364  * The channel is exclusively allocated and can't be used by another
365  * client before the owner calls mbox_free_channel.
366  * After assignment, any packet received on this channel will be
367  * handed over to the client via the 'rx_callback'.
368  * The framework holds reference to the client, so the mbox_client
369  * structure shouldn't be modified until the mbox_free_channel returns.
370  *
371  * Return: 0 if the channel was assigned to the client successfully.
372  *         <0 for request failure.
373  */
mbox_bind_client(struct mbox_chan * chan,struct mbox_client * cl)374 int mbox_bind_client(struct mbox_chan *chan, struct mbox_client *cl)
375 {
376 	int ret;
377 
378 	mutex_lock(&con_mutex);
379 	ret = __mbox_bind_client(chan, cl);
380 	mutex_unlock(&con_mutex);
381 
382 	return ret;
383 }
384 EXPORT_SYMBOL_GPL(mbox_bind_client);
385 
386 /**
387  * mbox_request_channel - Request a mailbox channel.
388  * @cl: Identity of the client requesting the channel.
389  * @index: Index of mailbox specifier in 'mboxes' property.
390  *
391  * The Client specifies its requirements and capabilities while asking for
392  * a mailbox channel. It can't be called from atomic context.
393  * The channel is exclusively allocated and can't be used by another
394  * client before the owner calls mbox_free_channel.
395  * After assignment, any packet received on this channel will be
396  * handed over to the client via the 'rx_callback'.
397  * The framework holds reference to the client, so the mbox_client
398  * structure shouldn't be modified until the mbox_free_channel returns.
399  *
400  * Return: Pointer to the channel assigned to the client if successful.
401  *		ERR_PTR for request failure.
402  */
mbox_request_channel(struct mbox_client * cl,int index)403 struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
404 {
405 	struct device *dev = cl->dev;
406 	struct mbox_controller *mbox;
407 	struct of_phandle_args spec;
408 	struct mbox_chan *chan;
409 	int ret;
410 
411 	if (!dev || !dev->of_node) {
412 		pr_debug("%s: No owner device node\n", __func__);
413 		return ERR_PTR(-ENODEV);
414 	}
415 
416 	mutex_lock(&con_mutex);
417 
418 	if (of_parse_phandle_with_args(dev->of_node, "mboxes",
419 				       "#mbox-cells", index, &spec)) {
420 		dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
421 		mutex_unlock(&con_mutex);
422 		return ERR_PTR(-ENODEV);
423 	}
424 
425 	chan = ERR_PTR(-EPROBE_DEFER);
426 	list_for_each_entry(mbox, &mbox_cons, node)
427 		if (mbox->dev->of_node == spec.np) {
428 			chan = mbox->of_xlate(mbox, &spec);
429 			if (!IS_ERR(chan))
430 				break;
431 		}
432 
433 	of_node_put(spec.np);
434 
435 	if (IS_ERR(chan)) {
436 		mutex_unlock(&con_mutex);
437 		return chan;
438 	}
439 
440 	ret = __mbox_bind_client(chan, cl);
441 	if (ret)
442 		chan = ERR_PTR(ret);
443 
444 	mutex_unlock(&con_mutex);
445 	return chan;
446 }
447 EXPORT_SYMBOL_GPL(mbox_request_channel);
448 
mbox_request_channel_byname(struct mbox_client * cl,const char * name)449 struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
450 					      const char *name)
451 {
452 	struct device_node *np = cl->dev->of_node;
453 	struct property *prop;
454 	const char *mbox_name;
455 	int index = 0;
456 
457 	if (!np) {
458 		dev_err(cl->dev, "%s() currently only supports DT\n", __func__);
459 		return ERR_PTR(-EINVAL);
460 	}
461 
462 	if (!of_get_property(np, "mbox-names", NULL)) {
463 		dev_err(cl->dev,
464 			"%s() requires an \"mbox-names\" property\n", __func__);
465 		return ERR_PTR(-EINVAL);
466 	}
467 
468 	of_property_for_each_string(np, "mbox-names", prop, mbox_name) {
469 		if (!strncmp(name, mbox_name, strlen(name)))
470 			return mbox_request_channel(cl, index);
471 		index++;
472 	}
473 
474 	dev_err(cl->dev, "%s() could not locate channel named \"%s\"\n",
475 		__func__, name);
476 	return ERR_PTR(-EINVAL);
477 }
478 EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
479 
480 /**
481  * mbox_free_channel - The client relinquishes control of a mailbox
482  *			channel by this call.
483  * @chan: The mailbox channel to be freed.
484  */
mbox_free_channel(struct mbox_chan * chan)485 void mbox_free_channel(struct mbox_chan *chan)
486 {
487 	unsigned long flags;
488 
489 	if (!chan || !chan->cl)
490 		return;
491 
492 	if (chan->mbox->ops->shutdown)
493 		chan->mbox->ops->shutdown(chan);
494 
495 	/* The queued TX requests are simply aborted, no callbacks are made */
496 	spin_lock_irqsave(&chan->lock, flags);
497 	chan->cl = NULL;
498 	chan->active_req = NULL;
499 	if (chan->txdone_method == TXDONE_BY_ACK)
500 		chan->txdone_method = TXDONE_BY_POLL;
501 
502 	module_put(chan->mbox->dev->driver->owner);
503 	spin_unlock_irqrestore(&chan->lock, flags);
504 }
505 EXPORT_SYMBOL_GPL(mbox_free_channel);
506 
507 static struct mbox_chan *
of_mbox_index_xlate(struct mbox_controller * mbox,const struct of_phandle_args * sp)508 of_mbox_index_xlate(struct mbox_controller *mbox,
509 		    const struct of_phandle_args *sp)
510 {
511 	int ind = sp->args[0];
512 
513 	if (ind >= mbox->num_chans)
514 		return ERR_PTR(-EINVAL);
515 
516 	return &mbox->chans[ind];
517 }
518 
519 /**
520  * mbox_controller_register - Register the mailbox controller
521  * @mbox:	Pointer to the mailbox controller.
522  *
523  * The controller driver registers its communication channels
524  */
mbox_controller_register(struct mbox_controller * mbox)525 int mbox_controller_register(struct mbox_controller *mbox)
526 {
527 	int i, txdone;
528 
529 	/* Sanity check */
530 	if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
531 		return -EINVAL;
532 
533 	if (mbox->txdone_irq)
534 		txdone = TXDONE_BY_IRQ;
535 	else if (mbox->txdone_poll)
536 		txdone = TXDONE_BY_POLL;
537 	else /* It has to be ACK then */
538 		txdone = TXDONE_BY_ACK;
539 
540 	if (txdone == TXDONE_BY_POLL) {
541 
542 		if (!mbox->ops->last_tx_done) {
543 			dev_err(mbox->dev, "last_tx_done method is absent\n");
544 			return -EINVAL;
545 		}
546 
547 		hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
548 			     HRTIMER_MODE_REL);
549 		mbox->poll_hrt.function = txdone_hrtimer;
550 		spin_lock_init(&mbox->poll_hrt_lock);
551 	}
552 
553 	for (i = 0; i < mbox->num_chans; i++) {
554 		struct mbox_chan *chan = &mbox->chans[i];
555 
556 		chan->cl = NULL;
557 		chan->mbox = mbox;
558 		chan->txdone_method = txdone;
559 		spin_lock_init(&chan->lock);
560 	}
561 
562 	if (!mbox->of_xlate)
563 		mbox->of_xlate = of_mbox_index_xlate;
564 
565 	mutex_lock(&con_mutex);
566 	list_add_tail(&mbox->node, &mbox_cons);
567 	mutex_unlock(&con_mutex);
568 
569 	return 0;
570 }
571 EXPORT_SYMBOL_GPL(mbox_controller_register);
572 
573 /**
574  * mbox_controller_unregister - Unregister the mailbox controller
575  * @mbox:	Pointer to the mailbox controller.
576  */
mbox_controller_unregister(struct mbox_controller * mbox)577 void mbox_controller_unregister(struct mbox_controller *mbox)
578 {
579 	int i;
580 
581 	if (!mbox)
582 		return;
583 
584 	mutex_lock(&con_mutex);
585 
586 	list_del(&mbox->node);
587 
588 	for (i = 0; i < mbox->num_chans; i++)
589 		mbox_free_channel(&mbox->chans[i]);
590 
591 	if (mbox->txdone_poll)
592 		hrtimer_cancel(&mbox->poll_hrt);
593 
594 	mutex_unlock(&con_mutex);
595 }
596 EXPORT_SYMBOL_GPL(mbox_controller_unregister);
597 
__devm_mbox_controller_unregister(struct device * dev,void * res)598 static void __devm_mbox_controller_unregister(struct device *dev, void *res)
599 {
600 	struct mbox_controller **mbox = res;
601 
602 	mbox_controller_unregister(*mbox);
603 }
604 
devm_mbox_controller_match(struct device * dev,void * res,void * data)605 static int devm_mbox_controller_match(struct device *dev, void *res, void *data)
606 {
607 	struct mbox_controller **mbox = res;
608 
609 	if (WARN_ON(!mbox || !*mbox))
610 		return 0;
611 
612 	return *mbox == data;
613 }
614 
615 /**
616  * devm_mbox_controller_register() - managed mbox_controller_register()
617  * @dev: device owning the mailbox controller being registered
618  * @mbox: mailbox controller being registered
619  *
620  * This function adds a device-managed resource that will make sure that the
621  * mailbox controller, which is registered using mbox_controller_register()
622  * as part of this function, will be unregistered along with the rest of
623  * device-managed resources upon driver probe failure or driver removal.
624  *
625  * Returns 0 on success or a negative error code on failure.
626  */
devm_mbox_controller_register(struct device * dev,struct mbox_controller * mbox)627 int devm_mbox_controller_register(struct device *dev,
628 				  struct mbox_controller *mbox)
629 {
630 	struct mbox_controller **ptr;
631 	int err;
632 
633 	ptr = devres_alloc(__devm_mbox_controller_unregister, sizeof(*ptr),
634 			   GFP_KERNEL);
635 	if (!ptr)
636 		return -ENOMEM;
637 
638 	err = mbox_controller_register(mbox);
639 	if (err < 0) {
640 		devres_free(ptr);
641 		return err;
642 	}
643 
644 	devres_add(dev, ptr);
645 	*ptr = mbox;
646 
647 	return 0;
648 }
649 EXPORT_SYMBOL_GPL(devm_mbox_controller_register);
650 
651 /**
652  * devm_mbox_controller_unregister() - managed mbox_controller_unregister()
653  * @dev: device owning the mailbox controller being unregistered
654  * @mbox: mailbox controller being unregistered
655  *
656  * This function unregisters the mailbox controller and removes the device-
657  * managed resource that was set up to automatically unregister the mailbox
658  * controller on driver probe failure or driver removal. It's typically not
659  * necessary to call this function.
660  */
devm_mbox_controller_unregister(struct device * dev,struct mbox_controller * mbox)661 void devm_mbox_controller_unregister(struct device *dev, struct mbox_controller *mbox)
662 {
663 	WARN_ON(devres_release(dev, __devm_mbox_controller_unregister,
664 			       devm_mbox_controller_match, mbox));
665 }
666 EXPORT_SYMBOL_GPL(devm_mbox_controller_unregister);
667