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