x86/speculation/mds: Fix documentation typo
[linux/fpc-iii.git] / drivers / mailbox / mailbox.c
blob537f4f6d009b2d0dbd1eeac62dd20212eef3fb02
1 /*
2 * Mailbox: Common code for Mailbox controllers and users
4 * Copyright (C) 2013-2014 Linaro Ltd.
5 * Author: Jassi Brar <jassisinghbrar@gmail.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 #include <linux/interrupt.h>
13 #include <linux/spinlock.h>
14 #include <linux/mutex.h>
15 #include <linux/delay.h>
16 #include <linux/slab.h>
17 #include <linux/err.h>
18 #include <linux/module.h>
19 #include <linux/device.h>
20 #include <linux/bitops.h>
21 #include <linux/mailbox_client.h>
22 #include <linux/mailbox_controller.h>
24 #include "mailbox.h"
26 static LIST_HEAD(mbox_cons);
27 static DEFINE_MUTEX(con_mutex);
29 static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
31 int idx;
32 unsigned long flags;
34 spin_lock_irqsave(&chan->lock, flags);
36 /* See if there is any space left */
37 if (chan->msg_count == MBOX_TX_QUEUE_LEN) {
38 spin_unlock_irqrestore(&chan->lock, flags);
39 return -ENOBUFS;
42 idx = chan->msg_free;
43 chan->msg_data[idx] = mssg;
44 chan->msg_count++;
46 if (idx == MBOX_TX_QUEUE_LEN - 1)
47 chan->msg_free = 0;
48 else
49 chan->msg_free++;
51 spin_unlock_irqrestore(&chan->lock, flags);
53 return idx;
56 static void msg_submit(struct mbox_chan *chan)
58 unsigned count, idx;
59 unsigned long flags;
60 void *data;
61 int err = -EBUSY;
63 spin_lock_irqsave(&chan->lock, flags);
65 if (!chan->msg_count || chan->active_req)
66 goto exit;
68 count = chan->msg_count;
69 idx = chan->msg_free;
70 if (idx >= count)
71 idx -= count;
72 else
73 idx += MBOX_TX_QUEUE_LEN - count;
75 data = chan->msg_data[idx];
77 if (chan->cl->tx_prepare)
78 chan->cl->tx_prepare(chan->cl, data);
79 /* Try to submit a message to the MBOX controller */
80 err = chan->mbox->ops->send_data(chan, data);
81 if (!err) {
82 chan->active_req = data;
83 chan->msg_count--;
85 exit:
86 spin_unlock_irqrestore(&chan->lock, flags);
88 if (!err && (chan->txdone_method & TXDONE_BY_POLL))
89 /* kick start the timer immediately to avoid delays */
90 hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
93 static void tx_tick(struct mbox_chan *chan, int r)
95 unsigned long flags;
96 void *mssg;
98 spin_lock_irqsave(&chan->lock, flags);
99 mssg = chan->active_req;
100 chan->active_req = NULL;
101 spin_unlock_irqrestore(&chan->lock, flags);
103 /* Submit next message */
104 msg_submit(chan);
106 if (!mssg)
107 return;
109 /* Notify the client */
110 if (chan->cl->tx_done)
111 chan->cl->tx_done(chan->cl, mssg, r);
113 if (r != -ETIME && chan->cl->tx_block)
114 complete(&chan->tx_complete);
117 static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
119 struct mbox_controller *mbox =
120 container_of(hrtimer, struct mbox_controller, poll_hrt);
121 bool txdone, resched = false;
122 int i;
124 for (i = 0; i < mbox->num_chans; i++) {
125 struct mbox_chan *chan = &mbox->chans[i];
127 if (chan->active_req && chan->cl) {
128 txdone = chan->mbox->ops->last_tx_done(chan);
129 if (txdone)
130 tx_tick(chan, 0);
131 else
132 resched = true;
136 if (resched) {
137 hrtimer_forward_now(hrtimer, ms_to_ktime(mbox->txpoll_period));
138 return HRTIMER_RESTART;
140 return HRTIMER_NORESTART;
144 * mbox_chan_received_data - A way for controller driver to push data
145 * received from remote to the upper layer.
146 * @chan: Pointer to the mailbox channel on which RX happened.
147 * @mssg: Client specific message typecasted as void *
149 * After startup and before shutdown any data received on the chan
150 * is passed on to the API via atomic mbox_chan_received_data().
151 * The controller should ACK the RX only after this call returns.
153 void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
155 /* No buffering the received data */
156 if (chan->cl->rx_callback)
157 chan->cl->rx_callback(chan->cl, mssg);
159 EXPORT_SYMBOL_GPL(mbox_chan_received_data);
162 * mbox_chan_txdone - A way for controller driver to notify the
163 * framework that the last TX has completed.
164 * @chan: Pointer to the mailbox chan on which TX happened.
165 * @r: Status of last TX - OK or ERROR
167 * The controller that has IRQ for TX ACK calls this atomic API
168 * to tick the TX state machine. It works only if txdone_irq
169 * is set by the controller.
171 void mbox_chan_txdone(struct mbox_chan *chan, int r)
173 if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
174 dev_err(chan->mbox->dev,
175 "Controller can't run the TX ticker\n");
176 return;
179 tx_tick(chan, r);
181 EXPORT_SYMBOL_GPL(mbox_chan_txdone);
184 * mbox_client_txdone - The way for a client to run the TX state machine.
185 * @chan: Mailbox channel assigned to this client.
186 * @r: Success status of last transmission.
188 * The client/protocol had received some 'ACK' packet and it notifies
189 * the API that the last packet was sent successfully. This only works
190 * if the controller can't sense TX-Done.
192 void mbox_client_txdone(struct mbox_chan *chan, int r)
194 if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
195 dev_err(chan->mbox->dev, "Client can't run the TX ticker\n");
196 return;
199 tx_tick(chan, r);
201 EXPORT_SYMBOL_GPL(mbox_client_txdone);
204 * mbox_client_peek_data - A way for client driver to pull data
205 * received from remote by the controller.
206 * @chan: Mailbox channel assigned to this client.
208 * A poke to controller driver for any received data.
209 * The data is actually passed onto client via the
210 * mbox_chan_received_data()
211 * The call can be made from atomic context, so the controller's
212 * implementation of peek_data() must not sleep.
214 * Return: True, if controller has, and is going to push after this,
215 * some data.
216 * False, if controller doesn't have any data to be read.
218 bool mbox_client_peek_data(struct mbox_chan *chan)
220 if (chan->mbox->ops->peek_data)
221 return chan->mbox->ops->peek_data(chan);
223 return false;
225 EXPORT_SYMBOL_GPL(mbox_client_peek_data);
228 * mbox_send_message - For client to submit a message to be
229 * sent to the remote.
230 * @chan: Mailbox channel assigned to this client.
231 * @mssg: Client specific message typecasted.
233 * For client to submit data to the controller destined for a remote
234 * processor. If the client had set 'tx_block', the call will return
235 * either when the remote receives the data or when 'tx_tout' millisecs
236 * run out.
237 * In non-blocking mode, the requests are buffered by the API and a
238 * non-negative token is returned for each queued request. If the request
239 * is not queued, a negative token is returned. Upon failure or successful
240 * TX, the API calls 'tx_done' from atomic context, from which the client
241 * could submit yet another request.
242 * The pointer to message should be preserved until it is sent
243 * over the chan, i.e, tx_done() is made.
244 * This function could be called from atomic context as it simply
245 * queues the data and returns a token against the request.
247 * Return: Non-negative integer for successful submission (non-blocking mode)
248 * or transmission over chan (blocking mode).
249 * Negative value denotes failure.
251 int mbox_send_message(struct mbox_chan *chan, void *mssg)
253 int t;
255 if (!chan || !chan->cl)
256 return -EINVAL;
258 t = add_to_rbuf(chan, mssg);
259 if (t < 0) {
260 dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
261 return t;
264 msg_submit(chan);
266 if (chan->cl->tx_block) {
267 unsigned long wait;
268 int ret;
270 if (!chan->cl->tx_tout) /* wait forever */
271 wait = msecs_to_jiffies(3600000);
272 else
273 wait = msecs_to_jiffies(chan->cl->tx_tout);
275 ret = wait_for_completion_timeout(&chan->tx_complete, wait);
276 if (ret == 0) {
277 t = -ETIME;
278 tx_tick(chan, t);
282 return t;
284 EXPORT_SYMBOL_GPL(mbox_send_message);
287 * mbox_request_channel - Request a mailbox channel.
288 * @cl: Identity of the client requesting the channel.
289 * @index: Index of mailbox specifier in 'mboxes' property.
291 * The Client specifies its requirements and capabilities while asking for
292 * a mailbox channel. It can't be called from atomic context.
293 * The channel is exclusively allocated and can't be used by another
294 * client before the owner calls mbox_free_channel.
295 * After assignment, any packet received on this channel will be
296 * handed over to the client via the 'rx_callback'.
297 * The framework holds reference to the client, so the mbox_client
298 * structure shouldn't be modified until the mbox_free_channel returns.
300 * Return: Pointer to the channel assigned to the client if successful.
301 * ERR_PTR for request failure.
303 struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
305 struct device *dev = cl->dev;
306 struct mbox_controller *mbox;
307 struct of_phandle_args spec;
308 struct mbox_chan *chan;
309 unsigned long flags;
310 int ret;
312 if (!dev || !dev->of_node) {
313 pr_debug("%s: No owner device node\n", __func__);
314 return ERR_PTR(-ENODEV);
317 mutex_lock(&con_mutex);
319 if (of_parse_phandle_with_args(dev->of_node, "mboxes",
320 "#mbox-cells", index, &spec)) {
321 dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
322 mutex_unlock(&con_mutex);
323 return ERR_PTR(-ENODEV);
326 chan = ERR_PTR(-EPROBE_DEFER);
327 list_for_each_entry(mbox, &mbox_cons, node)
328 if (mbox->dev->of_node == spec.np) {
329 chan = mbox->of_xlate(mbox, &spec);
330 break;
333 of_node_put(spec.np);
335 if (IS_ERR(chan)) {
336 mutex_unlock(&con_mutex);
337 return chan;
340 if (chan->cl || !try_module_get(mbox->dev->driver->owner)) {
341 dev_dbg(dev, "%s: mailbox not free\n", __func__);
342 mutex_unlock(&con_mutex);
343 return ERR_PTR(-EBUSY);
346 spin_lock_irqsave(&chan->lock, flags);
347 chan->msg_free = 0;
348 chan->msg_count = 0;
349 chan->active_req = NULL;
350 chan->cl = cl;
351 init_completion(&chan->tx_complete);
353 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
354 chan->txdone_method |= TXDONE_BY_ACK;
356 spin_unlock_irqrestore(&chan->lock, flags);
358 if (chan->mbox->ops->startup) {
359 ret = chan->mbox->ops->startup(chan);
361 if (ret) {
362 dev_err(dev, "Unable to startup the chan (%d)\n", ret);
363 mbox_free_channel(chan);
364 chan = ERR_PTR(ret);
368 mutex_unlock(&con_mutex);
369 return chan;
371 EXPORT_SYMBOL_GPL(mbox_request_channel);
373 struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
374 const char *name)
376 struct device_node *np = cl->dev->of_node;
377 struct property *prop;
378 const char *mbox_name;
379 int index = 0;
381 if (!np) {
382 dev_err(cl->dev, "%s() currently only supports DT\n", __func__);
383 return ERR_PTR(-EINVAL);
386 if (!of_get_property(np, "mbox-names", NULL)) {
387 dev_err(cl->dev,
388 "%s() requires an \"mbox-names\" property\n", __func__);
389 return ERR_PTR(-EINVAL);
392 of_property_for_each_string(np, "mbox-names", prop, mbox_name) {
393 if (!strncmp(name, mbox_name, strlen(name)))
394 break;
395 index++;
398 return mbox_request_channel(cl, index);
400 EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
403 * mbox_free_channel - The client relinquishes control of a mailbox
404 * channel by this call.
405 * @chan: The mailbox channel to be freed.
407 void mbox_free_channel(struct mbox_chan *chan)
409 unsigned long flags;
411 if (!chan || !chan->cl)
412 return;
414 if (chan->mbox->ops->shutdown)
415 chan->mbox->ops->shutdown(chan);
417 /* The queued TX requests are simply aborted, no callbacks are made */
418 spin_lock_irqsave(&chan->lock, flags);
419 chan->cl = NULL;
420 chan->active_req = NULL;
421 if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
422 chan->txdone_method = TXDONE_BY_POLL;
424 module_put(chan->mbox->dev->driver->owner);
425 spin_unlock_irqrestore(&chan->lock, flags);
427 EXPORT_SYMBOL_GPL(mbox_free_channel);
429 static struct mbox_chan *
430 of_mbox_index_xlate(struct mbox_controller *mbox,
431 const struct of_phandle_args *sp)
433 int ind = sp->args[0];
435 if (ind >= mbox->num_chans)
436 return ERR_PTR(-EINVAL);
438 return &mbox->chans[ind];
442 * mbox_controller_register - Register the mailbox controller
443 * @mbox: Pointer to the mailbox controller.
445 * The controller driver registers its communication channels
447 int mbox_controller_register(struct mbox_controller *mbox)
449 int i, txdone;
451 /* Sanity check */
452 if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
453 return -EINVAL;
455 if (mbox->txdone_irq)
456 txdone = TXDONE_BY_IRQ;
457 else if (mbox->txdone_poll)
458 txdone = TXDONE_BY_POLL;
459 else /* It has to be ACK then */
460 txdone = TXDONE_BY_ACK;
462 if (txdone == TXDONE_BY_POLL) {
464 if (!mbox->ops->last_tx_done) {
465 dev_err(mbox->dev, "last_tx_done method is absent\n");
466 return -EINVAL;
469 hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
470 HRTIMER_MODE_REL);
471 mbox->poll_hrt.function = txdone_hrtimer;
474 for (i = 0; i < mbox->num_chans; i++) {
475 struct mbox_chan *chan = &mbox->chans[i];
477 chan->cl = NULL;
478 chan->mbox = mbox;
479 chan->txdone_method = txdone;
480 spin_lock_init(&chan->lock);
483 if (!mbox->of_xlate)
484 mbox->of_xlate = of_mbox_index_xlate;
486 mutex_lock(&con_mutex);
487 list_add_tail(&mbox->node, &mbox_cons);
488 mutex_unlock(&con_mutex);
490 return 0;
492 EXPORT_SYMBOL_GPL(mbox_controller_register);
495 * mbox_controller_unregister - Unregister the mailbox controller
496 * @mbox: Pointer to the mailbox controller.
498 void mbox_controller_unregister(struct mbox_controller *mbox)
500 int i;
502 if (!mbox)
503 return;
505 mutex_lock(&con_mutex);
507 list_del(&mbox->node);
509 for (i = 0; i < mbox->num_chans; i++)
510 mbox_free_channel(&mbox->chans[i]);
512 if (mbox->txdone_poll)
513 hrtimer_cancel(&mbox->poll_hrt);
515 mutex_unlock(&con_mutex);
517 EXPORT_SYMBOL_GPL(mbox_controller_unregister);