drivers/mailbox/mailbox.c

   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         /* 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
  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
 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  */
 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  */
 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  */
 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  */
 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  */
 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  */
 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  */
 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
 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  */
 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 *
 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  */
 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  */
 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
 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
 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  */
 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  */
 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);