root/drivers/mailbox/mailbox.c

DEFINITIONS

1. add_to_rbuf
2. msg_submit
3. tx_tick
4. txdone_hrtimer
5. mbox_chan_received_data
6. mbox_chan_txdone
7. mbox_client_txdone
8. mbox_client_peek_data
9. mbox_send_message
10. mbox_flush
11. mbox_request_channel
12. mbox_request_channel_byname
13. mbox_free_channel
14. of_mbox_index_xlate
15. mbox_controller_register
16. mbox_controller_unregister
17. __devm_mbox_controller_unregister
18. devm_mbox_controller_match
19. devm_mbox_controller_register
20. devm_mbox_controller_unregister

   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                         return mbox_request_channel(cl, index);
 422                 index++;
 423         }
 424 
 425         dev_err(cl->dev, "%s() could not locate channel named \"%s\"\n",
 426                 __func__, name);
 427         return ERR_PTR(-EINVAL);
 428 }
 429 EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
 430 
 431 /**
 432  * mbox_free_channel - The client relinquishes control of a mailbox
 433  *                      channel by this call.
 434  * @chan: The mailbox channel to be freed.
 435  */
 436 void mbox_free_channel(struct mbox_chan *chan)
 437 {
 438         unsigned long flags;
 439 
 440         if (!chan || !chan->cl)
 441                 return;
 442 
 443         if (chan->mbox->ops->shutdown)
 444                 chan->mbox->ops->shutdown(chan);
 445 
 446         /* The queued TX requests are simply aborted, no callbacks are made */
 447         spin_lock_irqsave(&chan->lock, flags);
 448         chan->cl = NULL;
 449         chan->active_req = NULL;
 450         if (chan->txdone_method == TXDONE_BY_ACK)
 451                 chan->txdone_method = TXDONE_BY_POLL;
 452 
 453         module_put(chan->mbox->dev->driver->owner);
 454         spin_unlock_irqrestore(&chan->lock, flags);
 455 }
 456 EXPORT_SYMBOL_GPL(mbox_free_channel);
 457 
 458 static struct mbox_chan *
 459 of_mbox_index_xlate(struct mbox_controller *mbox,
 460                     const struct of_phandle_args *sp)
 461 {
 462         int ind = sp->args[0];
 463 
 464         if (ind >= mbox->num_chans)
 465                 return ERR_PTR(-EINVAL);
 466 
 467         return &mbox->chans[ind];
 468 }
 469 
 470 /**
 471  * mbox_controller_register - Register the mailbox controller
 472  * @mbox:       Pointer to the mailbox controller.
 473  *
 474  * The controller driver registers its communication channels
 475  */
 476 int mbox_controller_register(struct mbox_controller *mbox)
 477 {
 478         int i, txdone;
 479 
 480         /* Sanity check */
 481         if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
 482                 return -EINVAL;
 483 
 484         if (mbox->txdone_irq)
 485                 txdone = TXDONE_BY_IRQ;
 486         else if (mbox->txdone_poll)
 487                 txdone = TXDONE_BY_POLL;
 488         else /* It has to be ACK then */
 489                 txdone = TXDONE_BY_ACK;
 490 
 491         if (txdone == TXDONE_BY_POLL) {
 492 
 493                 if (!mbox->ops->last_tx_done) {
 494                         dev_err(mbox->dev, "last_tx_done method is absent\n");
 495                         return -EINVAL;
 496                 }
 497 
 498                 hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
 499                              HRTIMER_MODE_REL);
 500                 mbox->poll_hrt.function = txdone_hrtimer;
 501         }
 502 
 503         for (i = 0; i < mbox->num_chans; i++) {
 504                 struct mbox_chan *chan = &mbox->chans[i];
 505 
 506                 chan->cl = NULL;
 507                 chan->mbox = mbox;
 508                 chan->txdone_method = txdone;
 509                 spin_lock_init(&chan->lock);
 510         }
 511 
 512         if (!mbox->of_xlate)
 513                 mbox->of_xlate = of_mbox_index_xlate;
 514 
 515         mutex_lock(&con_mutex);
 516         list_add_tail(&mbox->node, &mbox_cons);
 517         mutex_unlock(&con_mutex);
 518 
 519         return 0;
 520 }
 521 EXPORT_SYMBOL_GPL(mbox_controller_register);
 522 
 523 /**
 524  * mbox_controller_unregister - Unregister the mailbox controller
 525  * @mbox:       Pointer to the mailbox controller.
 526  */
 527 void mbox_controller_unregister(struct mbox_controller *mbox)
 528 {
 529         int i;
 530 
 531         if (!mbox)
 532                 return;
 533 
 534         mutex_lock(&con_mutex);
 535 
 536         list_del(&mbox->node);
 537 
 538         for (i = 0; i < mbox->num_chans; i++)
 539                 mbox_free_channel(&mbox->chans[i]);
 540 
 541         if (mbox->txdone_poll)
 542                 hrtimer_cancel(&mbox->poll_hrt);
 543 
 544         mutex_unlock(&con_mutex);
 545 }
 546 EXPORT_SYMBOL_GPL(mbox_controller_unregister);
 547 
 548 static void __devm_mbox_controller_unregister(struct device *dev, void *res)
 549 {
 550         struct mbox_controller **mbox = res;
 551 
 552         mbox_controller_unregister(*mbox);
 553 }
 554 
 555 static int devm_mbox_controller_match(struct device *dev, void *res, void *data)
 556 {
 557         struct mbox_controller **mbox = res;
 558 
 559         if (WARN_ON(!mbox || !*mbox))
 560                 return 0;
 561 
 562         return *mbox == data;
 563 }
 564 
 565 /**
 566  * devm_mbox_controller_register() - managed mbox_controller_register()
 567  * @dev: device owning the mailbox controller being registered
 568  * @mbox: mailbox controller being registered
 569  *
 570  * This function adds a device-managed resource that will make sure that the
 571  * mailbox controller, which is registered using mbox_controller_register()
 572  * as part of this function, will be unregistered along with the rest of
 573  * device-managed resources upon driver probe failure or driver removal.
 574  *
 575  * Returns 0 on success or a negative error code on failure.
 576  */
 577 int devm_mbox_controller_register(struct device *dev,
 578                                   struct mbox_controller *mbox)
 579 {
 580         struct mbox_controller **ptr;
 581         int err;
 582 
 583         ptr = devres_alloc(__devm_mbox_controller_unregister, sizeof(*ptr),
 584                            GFP_KERNEL);
 585         if (!ptr)
 586                 return -ENOMEM;
 587 
 588         err = mbox_controller_register(mbox);
 589         if (err < 0) {
 590                 devres_free(ptr);
 591                 return err;
 592         }
 593 
 594         devres_add(dev, ptr);
 595         *ptr = mbox;
 596 
 597         return 0;
 598 }
 599 EXPORT_SYMBOL_GPL(devm_mbox_controller_register);
 600 
 601 /**
 602  * devm_mbox_controller_unregister() - managed mbox_controller_unregister()
 603  * @dev: device owning the mailbox controller being unregistered
 604  * @mbox: mailbox controller being unregistered
 605  *
 606  * This function unregisters the mailbox controller and removes the device-
 607  * managed resource that was set up to automatically unregister the mailbox
 608  * controller on driver probe failure or driver removal. It's typically not
 609  * necessary to call this function.
 610  */
 611 void devm_mbox_controller_unregister(struct device *dev, struct mbox_controller *mbox)
 612 {
 613         WARN_ON(devres_release(dev, __devm_mbox_controller_unregister,
 614                                devm_mbox_controller_match, mbox));
 615 }
 616 EXPORT_SYMBOL_GPL(devm_mbox_controller_unregister);