xref: /linux/drivers/mailbox/mailbox.c (revision 4e95bc268b915c3a19ec8b9110f61e4ea41a1ed0)
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 
21 #include "mailbox.h"
22 
23 static LIST_HEAD(mbox_cons);
24 static DEFINE_MUTEX(con_mutex);
25 
26 static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
27 {
28 	int idx;
29 	unsigned long flags;
30 
31 	spin_lock_irqsave(&chan->lock, flags);
32 
33 	/* See if there is any space left */
34 	if (chan->msg_count == MBOX_TX_QUEUE_LEN) {
35 		spin_unlock_irqrestore(&chan->lock, flags);
36 		return -ENOBUFS;
37 	}
38 
39 	idx = chan->msg_free;
40 	chan->msg_data[idx] = mssg;
41 	chan->msg_count++;
42 
43 	if (idx == MBOX_TX_QUEUE_LEN - 1)
44 		chan->msg_free = 0;
45 	else
46 		chan->msg_free++;
47 
48 	spin_unlock_irqrestore(&chan->lock, flags);
49 
50 	return idx;
51 }
52 
53 static void msg_submit(struct mbox_chan *chan)
54 {
55 	unsigned count, idx;
56 	unsigned long flags;
57 	void *data;
58 	int err = -EBUSY;
59 
60 	spin_lock_irqsave(&chan->lock, flags);
61 
62 	if (!chan->msg_count || chan->active_req)
63 		goto exit;
64 
65 	count = chan->msg_count;
66 	idx = chan->msg_free;
67 	if (idx >= count)
68 		idx -= count;
69 	else
70 		idx += MBOX_TX_QUEUE_LEN - count;
71 
72 	data = chan->msg_data[idx];
73 
74 	if (chan->cl->tx_prepare)
75 		chan->cl->tx_prepare(chan->cl, data);
76 	/* Try to submit a message to the MBOX controller */
77 	err = chan->mbox->ops->send_data(chan, data);
78 	if (!err) {
79 		chan->active_req = data;
80 		chan->msg_count--;
81 	}
82 exit:
83 	spin_unlock_irqrestore(&chan->lock, flags);
84 
85 	if (!err && (chan->txdone_method & TXDONE_BY_POLL))
86 		/* kick start the timer immediately to avoid delays */
87 		hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
88 }
89 
90 static void tx_tick(struct mbox_chan *chan, int r)
91 {
92 	unsigned long flags;
93 	void *mssg;
94 
95 	spin_lock_irqsave(&chan->lock, flags);
96 	mssg = chan->active_req;
97 	chan->active_req = NULL;
98 	spin_unlock_irqrestore(&chan->lock, flags);
99 
100 	/* Submit next message */
101 	msg_submit(chan);
102 
103 	if (!mssg)
104 		return;
105 
106 	/* Notify the client */
107 	if (chan->cl->tx_done)
108 		chan->cl->tx_done(chan->cl, mssg, r);
109 
110 	if (r != -ETIME && chan->cl->tx_block)
111 		complete(&chan->tx_complete);
112 }
113 
114 static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
115 {
116 	struct mbox_controller *mbox =
117 		container_of(hrtimer, struct mbox_controller, poll_hrt);
118 	bool txdone, resched = false;
119 	int i;
120 
121 	for (i = 0; i < mbox->num_chans; i++) {
122 		struct mbox_chan *chan = &mbox->chans[i];
123 
124 		if (chan->active_req && chan->cl) {
125 			txdone = chan->mbox->ops->last_tx_done(chan);
126 			if (txdone)
127 				tx_tick(chan, 0);
128 			else
129 				resched = true;
130 		}
131 	}
132 
133 	if (resched) {
134 		hrtimer_forward_now(hrtimer, ms_to_ktime(mbox->txpoll_period));
135 		return HRTIMER_RESTART;
136 	}
137 	return HRTIMER_NORESTART;
138 }
139 
140 /**
141  * mbox_chan_received_data - A way for controller driver to push data
142  *				received from remote to the upper layer.
143  * @chan: Pointer to the mailbox channel on which RX happened.
144  * @mssg: Client specific message typecasted as void *
145  *
146  * After startup and before shutdown any data received on the chan
147  * is passed on to the API via atomic mbox_chan_received_data().
148  * The controller should ACK the RX only after this call returns.
149  */
150 void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
151 {
152 	/* No buffering the received data */
153 	if (chan->cl->rx_callback)
154 		chan->cl->rx_callback(chan->cl, mssg);
155 }
156 EXPORT_SYMBOL_GPL(mbox_chan_received_data);
157 
158 /**
159  * mbox_chan_txdone - A way for controller driver to notify the
160  *			framework that the last TX has completed.
161  * @chan: Pointer to the mailbox chan on which TX happened.
162  * @r: Status of last TX - OK or ERROR
163  *
164  * The controller that has IRQ for TX ACK calls this atomic API
165  * to tick the TX state machine. It works only if txdone_irq
166  * is set by the controller.
167  */
168 void mbox_chan_txdone(struct mbox_chan *chan, int r)
169 {
170 	if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
171 		dev_err(chan->mbox->dev,
172 		       "Controller can't run the TX ticker\n");
173 		return;
174 	}
175 
176 	tx_tick(chan, r);
177 }
178 EXPORT_SYMBOL_GPL(mbox_chan_txdone);
179 
180 /**
181  * mbox_client_txdone - The way for a client to run the TX state machine.
182  * @chan: Mailbox channel assigned to this client.
183  * @r: Success status of last transmission.
184  *
185  * The client/protocol had received some 'ACK' packet and it notifies
186  * the API that the last packet was sent successfully. This only works
187  * if the controller can't sense TX-Done.
188  */
189 void mbox_client_txdone(struct mbox_chan *chan, int r)
190 {
191 	if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
192 		dev_err(chan->mbox->dev, "Client can't run the TX ticker\n");
193 		return;
194 	}
195 
196 	tx_tick(chan, r);
197 }
198 EXPORT_SYMBOL_GPL(mbox_client_txdone);
199 
200 /**
201  * mbox_client_peek_data - A way for client driver to pull data
202  *			received from remote by the controller.
203  * @chan: Mailbox channel assigned to this client.
204  *
205  * A poke to controller driver for any received data.
206  * The data is actually passed onto client via the
207  * mbox_chan_received_data()
208  * The call can be made from atomic context, so the controller's
209  * implementation of peek_data() must not sleep.
210  *
211  * Return: True, if controller has, and is going to push after this,
212  *          some data.
213  *         False, if controller doesn't have any data to be read.
214  */
215 bool mbox_client_peek_data(struct mbox_chan *chan)
216 {
217 	if (chan->mbox->ops->peek_data)
218 		return chan->mbox->ops->peek_data(chan);
219 
220 	return false;
221 }
222 EXPORT_SYMBOL_GPL(mbox_client_peek_data);
223 
224 /**
225  * mbox_send_message -	For client to submit a message to be
226  *				sent to the remote.
227  * @chan: Mailbox channel assigned to this client.
228  * @mssg: Client specific message typecasted.
229  *
230  * For client to submit data to the controller destined for a remote
231  * processor. If the client had set 'tx_block', the call will return
232  * either when the remote receives the data or when 'tx_tout' millisecs
233  * run out.
234  *  In non-blocking mode, the requests are buffered by the API and a
235  * non-negative token is returned for each queued request. If the request
236  * is not queued, a negative token is returned. Upon failure or successful
237  * TX, the API calls 'tx_done' from atomic context, from which the client
238  * could submit yet another request.
239  * The pointer to message should be preserved until it is sent
240  * over the chan, i.e, tx_done() is made.
241  * This function could be called from atomic context as it simply
242  * queues the data and returns a token against the request.
243  *
244  * Return: Non-negative integer for successful submission (non-blocking mode)
245  *	or transmission over chan (blocking mode).
246  *	Negative value denotes failure.
247  */
248 int mbox_send_message(struct mbox_chan *chan, void *mssg)
249 {
250 	int t;
251 
252 	if (!chan || !chan->cl)
253 		return -EINVAL;
254 
255 	t = add_to_rbuf(chan, mssg);
256 	if (t < 0) {
257 		dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
258 		return t;
259 	}
260 
261 	msg_submit(chan);
262 
263 	if (chan->cl->tx_block) {
264 		unsigned long wait;
265 		int ret;
266 
267 		if (!chan->cl->tx_tout) /* wait forever */
268 			wait = msecs_to_jiffies(3600000);
269 		else
270 			wait = msecs_to_jiffies(chan->cl->tx_tout);
271 
272 		ret = wait_for_completion_timeout(&chan->tx_complete, wait);
273 		if (ret == 0) {
274 			t = -ETIME;
275 			tx_tick(chan, t);
276 		}
277 	}
278 
279 	return t;
280 }
281 EXPORT_SYMBOL_GPL(mbox_send_message);
282 
283 /**
284  * mbox_flush - flush a mailbox channel
285  * @chan: mailbox channel to flush
286  * @timeout: time, in milliseconds, to allow the flush operation to succeed
287  *
288  * Mailbox controllers that need to work in atomic context can implement the
289  * ->flush() callback to busy loop until a transmission has been completed.
290  * The implementation must call mbox_chan_txdone() upon success. Clients can
291  * call the mbox_flush() function at any time after mbox_send_message() to
292  * flush the transmission. After the function returns success, the mailbox
293  * transmission is guaranteed to have completed.
294  *
295  * Returns: 0 on success or a negative error code on failure.
296  */
297 int mbox_flush(struct mbox_chan *chan, unsigned long timeout)
298 {
299 	int ret;
300 
301 	if (!chan->mbox->ops->flush)
302 		return -ENOTSUPP;
303 
304 	ret = chan->mbox->ops->flush(chan, timeout);
305 	if (ret < 0)
306 		tx_tick(chan, ret);
307 
308 	return ret;
309 }
310 EXPORT_SYMBOL_GPL(mbox_flush);
311 
312 /**
313  * mbox_request_channel - Request a mailbox channel.
314  * @cl: Identity of the client requesting the channel.
315  * @index: Index of mailbox specifier in 'mboxes' property.
316  *
317  * The Client specifies its requirements and capabilities while asking for
318  * a mailbox channel. It can't be called from atomic context.
319  * The channel is exclusively allocated and can't be used by another
320  * client before the owner calls mbox_free_channel.
321  * After assignment, any packet received on this channel will be
322  * handed over to the client via the 'rx_callback'.
323  * The framework holds reference to the client, so the mbox_client
324  * structure shouldn't be modified until the mbox_free_channel returns.
325  *
326  * Return: Pointer to the channel assigned to the client if successful.
327  *		ERR_PTR for request failure.
328  */
329 struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
330 {
331 	struct device *dev = cl->dev;
332 	struct mbox_controller *mbox;
333 	struct of_phandle_args spec;
334 	struct mbox_chan *chan;
335 	unsigned long flags;
336 	int ret;
337 
338 	if (!dev || !dev->of_node) {
339 		pr_debug("%s: No owner device node\n", __func__);
340 		return ERR_PTR(-ENODEV);
341 	}
342 
343 	mutex_lock(&con_mutex);
344 
345 	if (of_parse_phandle_with_args(dev->of_node, "mboxes",
346 				       "#mbox-cells", index, &spec)) {
347 		dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
348 		mutex_unlock(&con_mutex);
349 		return ERR_PTR(-ENODEV);
350 	}
351 
352 	chan = ERR_PTR(-EPROBE_DEFER);
353 	list_for_each_entry(mbox, &mbox_cons, node)
354 		if (mbox->dev->of_node == spec.np) {
355 			chan = mbox->of_xlate(mbox, &spec);
356 			if (!IS_ERR(chan))
357 				break;
358 		}
359 
360 	of_node_put(spec.np);
361 
362 	if (IS_ERR(chan)) {
363 		mutex_unlock(&con_mutex);
364 		return chan;
365 	}
366 
367 	if (chan->cl || !try_module_get(mbox->dev->driver->owner)) {
368 		dev_dbg(dev, "%s: mailbox not free\n", __func__);
369 		mutex_unlock(&con_mutex);
370 		return ERR_PTR(-EBUSY);
371 	}
372 
373 	spin_lock_irqsave(&chan->lock, flags);
374 	chan->msg_free = 0;
375 	chan->msg_count = 0;
376 	chan->active_req = NULL;
377 	chan->cl = cl;
378 	init_completion(&chan->tx_complete);
379 
380 	if (chan->txdone_method	== TXDONE_BY_POLL && cl->knows_txdone)
381 		chan->txdone_method = TXDONE_BY_ACK;
382 
383 	spin_unlock_irqrestore(&chan->lock, flags);
384 
385 	if (chan->mbox->ops->startup) {
386 		ret = chan->mbox->ops->startup(chan);
387 
388 		if (ret) {
389 			dev_err(dev, "Unable to startup the chan (%d)\n", ret);
390 			mbox_free_channel(chan);
391 			chan = ERR_PTR(ret);
392 		}
393 	}
394 
395 	mutex_unlock(&con_mutex);
396 	return chan;
397 }
398 EXPORT_SYMBOL_GPL(mbox_request_channel);
399 
400 struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
401 					      const char *name)
402 {
403 	struct device_node *np = cl->dev->of_node;
404 	struct property *prop;
405 	const char *mbox_name;
406 	int index = 0;
407 
408 	if (!np) {
409 		dev_err(cl->dev, "%s() currently only supports DT\n", __func__);
410 		return ERR_PTR(-EINVAL);
411 	}
412 
413 	if (!of_get_property(np, "mbox-names", NULL)) {
414 		dev_err(cl->dev,
415 			"%s() requires an \"mbox-names\" property\n", __func__);
416 		return ERR_PTR(-EINVAL);
417 	}
418 
419 	of_property_for_each_string(np, "mbox-names", prop, mbox_name) {
420 		if (!strncmp(name, mbox_name, strlen(name)))
421 			break;
422 		index++;
423 	}
424 
425 	return mbox_request_channel(cl, index);
426 }
427 EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
428 
429 /**
430  * mbox_free_channel - The client relinquishes control of a mailbox
431  *			channel by this call.
432  * @chan: The mailbox channel to be freed.
433  */
434 void mbox_free_channel(struct mbox_chan *chan)
435 {
436 	unsigned long flags;
437 
438 	if (!chan || !chan->cl)
439 		return;
440 
441 	if (chan->mbox->ops->shutdown)
442 		chan->mbox->ops->shutdown(chan);
443 
444 	/* The queued TX requests are simply aborted, no callbacks are made */
445 	spin_lock_irqsave(&chan->lock, flags);
446 	chan->cl = NULL;
447 	chan->active_req = NULL;
448 	if (chan->txdone_method == TXDONE_BY_ACK)
449 		chan->txdone_method = TXDONE_BY_POLL;
450 
451 	module_put(chan->mbox->dev->driver->owner);
452 	spin_unlock_irqrestore(&chan->lock, flags);
453 }
454 EXPORT_SYMBOL_GPL(mbox_free_channel);
455 
456 static struct mbox_chan *
457 of_mbox_index_xlate(struct mbox_controller *mbox,
458 		    const struct of_phandle_args *sp)
459 {
460 	int ind = sp->args[0];
461 
462 	if (ind >= mbox->num_chans)
463 		return ERR_PTR(-EINVAL);
464 
465 	return &mbox->chans[ind];
466 }
467 
468 /**
469  * mbox_controller_register - Register the mailbox controller
470  * @mbox:	Pointer to the mailbox controller.
471  *
472  * The controller driver registers its communication channels
473  */
474 int mbox_controller_register(struct mbox_controller *mbox)
475 {
476 	int i, txdone;
477 
478 	/* Sanity check */
479 	if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
480 		return -EINVAL;
481 
482 	if (mbox->txdone_irq)
483 		txdone = TXDONE_BY_IRQ;
484 	else if (mbox->txdone_poll)
485 		txdone = TXDONE_BY_POLL;
486 	else /* It has to be ACK then */
487 		txdone = TXDONE_BY_ACK;
488 
489 	if (txdone == TXDONE_BY_POLL) {
490 
491 		if (!mbox->ops->last_tx_done) {
492 			dev_err(mbox->dev, "last_tx_done method is absent\n");
493 			return -EINVAL;
494 		}
495 
496 		hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
497 			     HRTIMER_MODE_REL);
498 		mbox->poll_hrt.function = txdone_hrtimer;
499 	}
500 
501 	for (i = 0; i < mbox->num_chans; i++) {
502 		struct mbox_chan *chan = &mbox->chans[i];
503 
504 		chan->cl = NULL;
505 		chan->mbox = mbox;
506 		chan->txdone_method = txdone;
507 		spin_lock_init(&chan->lock);
508 	}
509 
510 	if (!mbox->of_xlate)
511 		mbox->of_xlate = of_mbox_index_xlate;
512 
513 	mutex_lock(&con_mutex);
514 	list_add_tail(&mbox->node, &mbox_cons);
515 	mutex_unlock(&con_mutex);
516 
517 	return 0;
518 }
519 EXPORT_SYMBOL_GPL(mbox_controller_register);
520 
521 /**
522  * mbox_controller_unregister - Unregister the mailbox controller
523  * @mbox:	Pointer to the mailbox controller.
524  */
525 void mbox_controller_unregister(struct mbox_controller *mbox)
526 {
527 	int i;
528 
529 	if (!mbox)
530 		return;
531 
532 	mutex_lock(&con_mutex);
533 
534 	list_del(&mbox->node);
535 
536 	for (i = 0; i < mbox->num_chans; i++)
537 		mbox_free_channel(&mbox->chans[i]);
538 
539 	if (mbox->txdone_poll)
540 		hrtimer_cancel(&mbox->poll_hrt);
541 
542 	mutex_unlock(&con_mutex);
543 }
544 EXPORT_SYMBOL_GPL(mbox_controller_unregister);
545 
546 static void __devm_mbox_controller_unregister(struct device *dev, void *res)
547 {
548 	struct mbox_controller **mbox = res;
549 
550 	mbox_controller_unregister(*mbox);
551 }
552 
553 static int devm_mbox_controller_match(struct device *dev, void *res, void *data)
554 {
555 	struct mbox_controller **mbox = res;
556 
557 	if (WARN_ON(!mbox || !*mbox))
558 		return 0;
559 
560 	return *mbox == data;
561 }
562 
563 /**
564  * devm_mbox_controller_register() - managed mbox_controller_register()
565  * @dev: device owning the mailbox controller being registered
566  * @mbox: mailbox controller being registered
567  *
568  * This function adds a device-managed resource that will make sure that the
569  * mailbox controller, which is registered using mbox_controller_register()
570  * as part of this function, will be unregistered along with the rest of
571  * device-managed resources upon driver probe failure or driver removal.
572  *
573  * Returns 0 on success or a negative error code on failure.
574  */
575 int devm_mbox_controller_register(struct device *dev,
576 				  struct mbox_controller *mbox)
577 {
578 	struct mbox_controller **ptr;
579 	int err;
580 
581 	ptr = devres_alloc(__devm_mbox_controller_unregister, sizeof(*ptr),
582 			   GFP_KERNEL);
583 	if (!ptr)
584 		return -ENOMEM;
585 
586 	err = mbox_controller_register(mbox);
587 	if (err < 0) {
588 		devres_free(ptr);
589 		return err;
590 	}
591 
592 	devres_add(dev, ptr);
593 	*ptr = mbox;
594 
595 	return 0;
596 }
597 EXPORT_SYMBOL_GPL(devm_mbox_controller_register);
598 
599 /**
600  * devm_mbox_controller_unregister() - managed mbox_controller_unregister()
601  * @dev: device owning the mailbox controller being unregistered
602  * @mbox: mailbox controller being unregistered
603  *
604  * This function unregisters the mailbox controller and removes the device-
605  * managed resource that was set up to automatically unregister the mailbox
606  * controller on driver probe failure or driver removal. It's typically not
607  * necessary to call this function.
608  */
609 void devm_mbox_controller_unregister(struct device *dev, struct mbox_controller *mbox)
610 {
611 	WARN_ON(devres_release(dev, __devm_mbox_controller_unregister,
612 			       devm_mbox_controller_match, mbox));
613 }
614 EXPORT_SYMBOL_GPL(devm_mbox_controller_unregister);
615