1 /*
2 * Mailbox: Common code for Mailbox controllers and users
3 *
4 * Copyright (C) 2013-2014 Linaro Ltd.
5 * Author: Jassi Brar <jassisinghbrar@gmail.com>
6 *
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.
10 */
11
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>
23
24 #define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */
25 #define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */
26 #define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */
27
28 static LIST_HEAD(mbox_cons);
29 static DEFINE_MUTEX(con_mutex);
30
add_to_rbuf(struct mbox_chan * chan,void * mssg)31 static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
32 {
33 int idx;
34 unsigned long flags;
35
36 spin_lock_irqsave(&chan->lock, flags);
37
38 /* See if there is any space left */
39 if (chan->msg_count == MBOX_TX_QUEUE_LEN) {
40 spin_unlock_irqrestore(&chan->lock, flags);
41 return -ENOBUFS;
42 }
43
44 idx = chan->msg_free;
45 chan->msg_data[idx] = mssg;
46 chan->msg_count++;
47
48 if (idx == MBOX_TX_QUEUE_LEN - 1)
49 chan->msg_free = 0;
50 else
51 chan->msg_free++;
52
53 spin_unlock_irqrestore(&chan->lock, flags);
54
55 return idx;
56 }
57
msg_submit(struct mbox_chan * chan)58 static void msg_submit(struct mbox_chan *chan)
59 {
60 unsigned count, idx;
61 unsigned long flags;
62 void *data;
63 int err;
64
65 spin_lock_irqsave(&chan->lock, flags);
66
67 if (!chan->msg_count || chan->active_req)
68 goto exit;
69
70 count = chan->msg_count;
71 idx = chan->msg_free;
72 if (idx >= count)
73 idx -= count;
74 else
75 idx += MBOX_TX_QUEUE_LEN - count;
76
77 data = chan->msg_data[idx];
78
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--;
84 }
85 exit:
86 spin_unlock_irqrestore(&chan->lock, flags);
87 }
88
tx_tick(struct mbox_chan * chan,int r)89 static void tx_tick(struct mbox_chan *chan, int r)
90 {
91 unsigned long flags;
92 void *mssg;
93
94 spin_lock_irqsave(&chan->lock, flags);
95 mssg = chan->active_req;
96 chan->active_req = NULL;
97 spin_unlock_irqrestore(&chan->lock, flags);
98
99 /* Submit next message */
100 msg_submit(chan);
101
102 if (!mssg)
103 return;
104
105 /* Notify the client */
106 if (chan->cl->tx_done)
107 chan->cl->tx_done(chan->cl, mssg, r);
108
109 if (r != -ETIME && chan->cl->tx_block)
110 complete(&chan->tx_complete);
111 }
112
poll_txdone(unsigned long data)113 static void poll_txdone(unsigned long data)
114 {
115 struct mbox_controller *mbox = (struct mbox_controller *)data;
116 bool txdone, resched = false;
117 int i;
118
119 for (i = 0; i < mbox->num_chans; i++) {
120 struct mbox_chan *chan = &mbox->chans[i];
121
122 if (chan->active_req && chan->cl) {
123 resched = true;
124 txdone = chan->mbox->ops->last_tx_done(chan);
125 if (txdone)
126 tx_tick(chan, 0);
127 }
128 }
129
130 if (resched)
131 mod_timer(&mbox->poll, jiffies +
132 msecs_to_jiffies(mbox->txpoll_period));
133 }
134
135 /**
136 * mbox_chan_received_data - A way for controller driver to push data
137 * received from remote to the upper layer.
138 * @chan: Pointer to the mailbox channel on which RX happened.
139 * @mssg: Client specific message typecasted as void *
140 *
141 * After startup and before shutdown any data received on the chan
142 * is passed on to the API via atomic mbox_chan_received_data().
143 * The controller should ACK the RX only after this call returns.
144 */
mbox_chan_received_data(struct mbox_chan * chan,void * mssg)145 void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
146 {
147 /* No buffering the received data */
148 if (chan->cl->rx_callback)
149 chan->cl->rx_callback(chan->cl, mssg);
150 }
151 EXPORT_SYMBOL_GPL(mbox_chan_received_data);
152
153 /**
154 * mbox_chan_txdone - A way for controller driver to notify the
155 * framework that the last TX has completed.
156 * @chan: Pointer to the mailbox chan on which TX happened.
157 * @r: Status of last TX - OK or ERROR
158 *
159 * The controller that has IRQ for TX ACK calls this atomic API
160 * to tick the TX state machine. It works only if txdone_irq
161 * is set by the controller.
162 */
mbox_chan_txdone(struct mbox_chan * chan,int r)163 void mbox_chan_txdone(struct mbox_chan *chan, int r)
164 {
165 if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
166 dev_err(chan->mbox->dev,
167 "Controller can't run the TX ticker\n");
168 return;
169 }
170
171 tx_tick(chan, r);
172 }
173 EXPORT_SYMBOL_GPL(mbox_chan_txdone);
174
175 /**
176 * mbox_client_txdone - The way for a client to run the TX state machine.
177 * @chan: Mailbox channel assigned to this client.
178 * @r: Success status of last transmission.
179 *
180 * The client/protocol had received some 'ACK' packet and it notifies
181 * the API that the last packet was sent successfully. This only works
182 * if the controller can't sense TX-Done.
183 */
mbox_client_txdone(struct mbox_chan * chan,int r)184 void mbox_client_txdone(struct mbox_chan *chan, int r)
185 {
186 if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
187 dev_err(chan->mbox->dev, "Client can't run the TX ticker\n");
188 return;
189 }
190
191 tx_tick(chan, r);
192 }
193 EXPORT_SYMBOL_GPL(mbox_client_txdone);
194
195 /**
196 * mbox_client_peek_data - A way for client driver to pull data
197 * received from remote by the controller.
198 * @chan: Mailbox channel assigned to this client.
199 *
200 * A poke to controller driver for any received data.
201 * The data is actually passed onto client via the
202 * mbox_chan_received_data()
203 * The call can be made from atomic context, so the controller's
204 * implementation of peek_data() must not sleep.
205 *
206 * Return: True, if controller has, and is going to push after this,
207 * some data.
208 * False, if controller doesn't have any data to be read.
209 */
mbox_client_peek_data(struct mbox_chan * chan)210 bool mbox_client_peek_data(struct mbox_chan *chan)
211 {
212 if (chan->mbox->ops->peek_data)
213 return chan->mbox->ops->peek_data(chan);
214
215 return false;
216 }
217 EXPORT_SYMBOL_GPL(mbox_client_peek_data);
218
219 /**
220 * mbox_send_message - For client to submit a message to be
221 * sent to the remote.
222 * @chan: Mailbox channel assigned to this client.
223 * @mssg: Client specific message typecasted.
224 *
225 * For client to submit data to the controller destined for a remote
226 * processor. If the client had set 'tx_block', the call will return
227 * either when the remote receives the data or when 'tx_tout' millisecs
228 * run out.
229 * In non-blocking mode, the requests are buffered by the API and a
230 * non-negative token is returned for each queued request. If the request
231 * is not queued, a negative token is returned. Upon failure or successful
232 * TX, the API calls 'tx_done' from atomic context, from which the client
233 * could submit yet another request.
234 * The pointer to message should be preserved until it is sent
235 * over the chan, i.e, tx_done() is made.
236 * This function could be called from atomic context as it simply
237 * queues the data and returns a token against the request.
238 *
239 * Return: Non-negative integer for successful submission (non-blocking mode)
240 * or transmission over chan (blocking mode).
241 * Negative value denotes failure.
242 */
mbox_send_message(struct mbox_chan * chan,void * mssg)243 int mbox_send_message(struct mbox_chan *chan, void *mssg)
244 {
245 int t;
246
247 if (!chan || !chan->cl)
248 return -EINVAL;
249
250 t = add_to_rbuf(chan, mssg);
251 if (t < 0) {
252 dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
253 return t;
254 }
255
256 msg_submit(chan);
257
258 if (chan->txdone_method == TXDONE_BY_POLL)
259 poll_txdone((unsigned long)chan->mbox);
260
261 if (chan->cl->tx_block) {
262 unsigned long wait;
263 int ret;
264
265 if (!chan->cl->tx_tout) /* wait forever */
266 wait = msecs_to_jiffies(3600000);
267 else
268 wait = msecs_to_jiffies(chan->cl->tx_tout);
269
270 ret = wait_for_completion_timeout(&chan->tx_complete, wait);
271 if (ret == 0) {
272 t = -ETIME;
273 tx_tick(chan, t);
274 }
275 }
276
277 return t;
278 }
279 EXPORT_SYMBOL_GPL(mbox_send_message);
280
281 /**
282 * mbox_request_channel - Request a mailbox channel.
283 * @cl: Identity of the client requesting the channel.
284 * @index: Index of mailbox specifier in 'mboxes' property.
285 *
286 * The Client specifies its requirements and capabilities while asking for
287 * a mailbox channel. It can't be called from atomic context.
288 * The channel is exclusively allocated and can't be used by another
289 * client before the owner calls mbox_free_channel.
290 * After assignment, any packet received on this channel will be
291 * handed over to the client via the 'rx_callback'.
292 * The framework holds reference to the client, so the mbox_client
293 * structure shouldn't be modified until the mbox_free_channel returns.
294 *
295 * Return: Pointer to the channel assigned to the client if successful.
296 * ERR_PTR for request failure.
297 */
mbox_request_channel(struct mbox_client * cl,int index)298 struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
299 {
300 struct device *dev = cl->dev;
301 struct mbox_controller *mbox;
302 struct of_phandle_args spec;
303 struct mbox_chan *chan;
304 unsigned long flags;
305 int ret;
306
307 if (!dev || !dev->of_node) {
308 pr_debug("%s: No owner device node\n", __func__);
309 return ERR_PTR(-ENODEV);
310 }
311
312 mutex_lock(&con_mutex);
313
314 if (of_parse_phandle_with_args(dev->of_node, "mboxes",
315 "#mbox-cells", index, &spec)) {
316 dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
317 mutex_unlock(&con_mutex);
318 return ERR_PTR(-ENODEV);
319 }
320
321 chan = NULL;
322 list_for_each_entry(mbox, &mbox_cons, node)
323 if (mbox->dev->of_node == spec.np) {
324 chan = mbox->of_xlate(mbox, &spec);
325 break;
326 }
327
328 of_node_put(spec.np);
329
330 if (!chan || chan->cl || !try_module_get(mbox->dev->driver->owner)) {
331 dev_dbg(dev, "%s: mailbox not free\n", __func__);
332 mutex_unlock(&con_mutex);
333 return ERR_PTR(-EBUSY);
334 }
335
336 spin_lock_irqsave(&chan->lock, flags);
337 chan->msg_free = 0;
338 chan->msg_count = 0;
339 chan->active_req = NULL;
340 chan->cl = cl;
341 init_completion(&chan->tx_complete);
342
343 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
344 chan->txdone_method |= TXDONE_BY_ACK;
345
346 spin_unlock_irqrestore(&chan->lock, flags);
347
348 ret = chan->mbox->ops->startup(chan);
349 if (ret) {
350 dev_err(dev, "Unable to startup the chan (%d)\n", ret);
351 mbox_free_channel(chan);
352 chan = ERR_PTR(ret);
353 }
354
355 mutex_unlock(&con_mutex);
356 return chan;
357 }
358 EXPORT_SYMBOL_GPL(mbox_request_channel);
359
360 /**
361 * mbox_free_channel - The client relinquishes control of a mailbox
362 * channel by this call.
363 * @chan: The mailbox channel to be freed.
364 */
mbox_free_channel(struct mbox_chan * chan)365 void mbox_free_channel(struct mbox_chan *chan)
366 {
367 unsigned long flags;
368
369 if (!chan || !chan->cl)
370 return;
371
372 chan->mbox->ops->shutdown(chan);
373
374 /* The queued TX requests are simply aborted, no callbacks are made */
375 spin_lock_irqsave(&chan->lock, flags);
376 chan->cl = NULL;
377 chan->active_req = NULL;
378 if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
379 chan->txdone_method = TXDONE_BY_POLL;
380
381 module_put(chan->mbox->dev->driver->owner);
382 spin_unlock_irqrestore(&chan->lock, flags);
383 }
384 EXPORT_SYMBOL_GPL(mbox_free_channel);
385
386 static struct mbox_chan *
of_mbox_index_xlate(struct mbox_controller * mbox,const struct of_phandle_args * sp)387 of_mbox_index_xlate(struct mbox_controller *mbox,
388 const struct of_phandle_args *sp)
389 {
390 int ind = sp->args[0];
391
392 if (ind >= mbox->num_chans)
393 return NULL;
394
395 return &mbox->chans[ind];
396 }
397
398 /**
399 * mbox_controller_register - Register the mailbox controller
400 * @mbox: Pointer to the mailbox controller.
401 *
402 * The controller driver registers its communication channels
403 */
mbox_controller_register(struct mbox_controller * mbox)404 int mbox_controller_register(struct mbox_controller *mbox)
405 {
406 int i, txdone;
407
408 /* Sanity check */
409 if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
410 return -EINVAL;
411
412 if (mbox->txdone_irq)
413 txdone = TXDONE_BY_IRQ;
414 else if (mbox->txdone_poll)
415 txdone = TXDONE_BY_POLL;
416 else /* It has to be ACK then */
417 txdone = TXDONE_BY_ACK;
418
419 if (txdone == TXDONE_BY_POLL) {
420 mbox->poll.function = &poll_txdone;
421 mbox->poll.data = (unsigned long)mbox;
422 init_timer(&mbox->poll);
423 }
424
425 for (i = 0; i < mbox->num_chans; i++) {
426 struct mbox_chan *chan = &mbox->chans[i];
427
428 chan->cl = NULL;
429 chan->mbox = mbox;
430 chan->txdone_method = txdone;
431 spin_lock_init(&chan->lock);
432 }
433
434 if (!mbox->of_xlate)
435 mbox->of_xlate = of_mbox_index_xlate;
436
437 mutex_lock(&con_mutex);
438 list_add_tail(&mbox->node, &mbox_cons);
439 mutex_unlock(&con_mutex);
440
441 return 0;
442 }
443 EXPORT_SYMBOL_GPL(mbox_controller_register);
444
445 /**
446 * mbox_controller_unregister - Unregister the mailbox controller
447 * @mbox: Pointer to the mailbox controller.
448 */
mbox_controller_unregister(struct mbox_controller * mbox)449 void mbox_controller_unregister(struct mbox_controller *mbox)
450 {
451 int i;
452
453 if (!mbox)
454 return;
455
456 mutex_lock(&con_mutex);
457
458 list_del(&mbox->node);
459
460 for (i = 0; i < mbox->num_chans; i++)
461 mbox_free_channel(&mbox->chans[i]);
462
463 if (mbox->txdone_poll)
464 del_timer_sync(&mbox->poll);
465
466 mutex_unlock(&con_mutex);
467 }
468 EXPORT_SYMBOL_GPL(mbox_controller_unregister);
469