drivers/mailbox/mailbox.c

   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 #include "mailbox.h"
  25
  26 static LIST_HEAD(mbox_cons);
  27 static DEFINE_MUTEX(con_mutex);
  28
  29 static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
  30 {
  31         int idx;
  32         unsigned long flags;
  33
  34         spin_lock_irqsave(&chan->lock, flags);
  35
  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;
  40         }
  41
  42         idx = chan->msg_free;
  43         chan->msg_data[idx] = mssg;
  44         chan->msg_count++;
  45
  46         if (idx == MBOX_TX_QUEUE_LEN - 1)
  47                 chan->msg_free = 0;
  48         else
  49                 chan->msg_free++;
  50
  51         spin_unlock_irqrestore(&chan->lock, flags);
  52
  53         return idx;
  54 }
  55
  56 static void msg_submit(struct mbox_chan *chan)
  57 {
  58         unsigned count, idx;
  59         unsigned long flags;
  60         void *data;
  61         int err = -EBUSY;
  62
  63         spin_lock_irqsave(&chan->lock, flags);
  64
  65         if (!chan->msg_count || chan->active_req)
  66                 goto exit;
  67
  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;
  74
  75         data = chan->msg_data[idx];
  76
  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--;
  84         }
  85 exit:
  86         spin_unlock_irqrestore(&chan->lock, flags);
  87
  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);
  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         /* Notify the client */
 107         if (mssg && chan->cl->tx_done)
 108                 chan->cl->tx_done(chan->cl, mssg, r);
 109
 110         if (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 && chan->active_req) {
 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 = -EIO;
 275                         tx_tick(chan, -EIO);
 276                 }
 277         }
 278
 279         return t;
 280 }
 281 EXPORT_SYMBOL_GPL(mbox_send_message);
 282
 283 /**
 284  * mbox_request_channel - Request a mailbox channel.
 285  * @cl: Identity of the client requesting the channel.
 286  * @index: Index of mailbox specifier in 'mboxes' property.
 287  *
 288  * The Client specifies its requirements and capabilities while asking for
 289  * a mailbox channel. It can't be called from atomic context.
 290  * The channel is exclusively allocated and can't be used by another
 291  * client before the owner calls mbox_free_channel.
 292  * After assignment, any packet received on this channel will be
 293  * handed over to the client via the 'rx_callback'.
 294  * The framework holds reference to the client, so the mbox_client
 295  * structure shouldn't be modified until the mbox_free_channel returns.
 296  *
 297  * Return: Pointer to the channel assigned to the client if successful.
 298  *              ERR_PTR for request failure.
 299  */
 300 struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
 301 {
 302         struct device *dev = cl->dev;
 303         struct mbox_controller *mbox;
 304         struct of_phandle_args spec;
 305         struct mbox_chan *chan;
 306         unsigned long flags;
 307         int ret;
 308
 309         if (!dev || !dev->of_node) {
 310                 pr_debug("%s: No owner device node\n", __func__);
 311                 return ERR_PTR(-ENODEV);
 312         }
 313
 314         mutex_lock(&con_mutex);
 315
 316         if (of_parse_phandle_with_args(dev->of_node, "mboxes",
 317                                        "#mbox-cells", index, &spec)) {
 318                 dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
 319                 mutex_unlock(&con_mutex);
 320                 return ERR_PTR(-ENODEV);
 321         }
 322
 323         chan = ERR_PTR(-EPROBE_DEFER);
 324         list_for_each_entry(mbox, &mbox_cons, node)
 325                 if (mbox->dev->of_node == spec.np) {
 326                         chan = mbox->of_xlate(mbox, &spec);
 327                         break;
 328                 }
 329
 330         of_node_put(spec.np);
 331
 332         if (IS_ERR(chan)) {
 333                 mutex_unlock(&con_mutex);
 334                 return chan;
 335         }
 336
 337         if (chan->cl || !try_module_get(mbox->dev->driver->owner)) {
 338                 dev_dbg(dev, "%s: mailbox not free\n", __func__);
 339                 mutex_unlock(&con_mutex);
 340                 return ERR_PTR(-EBUSY);
 341         }
 342
 343         spin_lock_irqsave(&chan->lock, flags);
 344         chan->msg_free = 0;
 345         chan->msg_count = 0;
 346         chan->active_req = NULL;
 347         chan->cl = cl;
 348         init_completion(&chan->tx_complete);
 349
 350         if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
 351                 chan->txdone_method |= TXDONE_BY_ACK;
 352
 353         spin_unlock_irqrestore(&chan->lock, flags);
 354
 355         ret = chan->mbox->ops->startup(chan);
 356         if (ret) {
 357                 dev_err(dev, "Unable to startup the chan (%d)\n", ret);
 358                 mbox_free_channel(chan);
 359                 chan = ERR_PTR(ret);
 360         }
 361
 362         mutex_unlock(&con_mutex);
 363         return chan;
 364 }
 365 EXPORT_SYMBOL_GPL(mbox_request_channel);
 366
 367 struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
 368                                               const char *name)
 369 {
 370         struct device_node *np = cl->dev->of_node;
 371         struct property *prop;
 372         const char *mbox_name;
 373         int index = 0;
 374
 375         if (!np) {
 376                 dev_err(cl->dev, "%s() currently only supports DT\n", __func__);
 377                 return ERR_PTR(-EINVAL);
 378         }
 379
 380         if (!of_get_property(np, "mbox-names", NULL)) {
 381                 dev_err(cl->dev,
 382                         "%s() requires an \"mbox-names\" property\n", __func__);
 383                 return ERR_PTR(-EINVAL);
 384         }
 385
 386         of_property_for_each_string(np, "mbox-names", prop, mbox_name) {
 387                 if (!strncmp(name, mbox_name, strlen(name)))
 388                         break;
 389                 index++;
 390         }
 391
 392         return mbox_request_channel(cl, index);
 393 }
 394 EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
 395
 396 /**
 397  * mbox_free_channel - The client relinquishes control of a mailbox
 398  *                      channel by this call.
 399  * @chan: The mailbox channel to be freed.
 400  */
 401 void mbox_free_channel(struct mbox_chan *chan)
 402 {
 403         unsigned long flags;
 404
 405         if (!chan || !chan->cl)
 406                 return;
 407
 408         chan->mbox->ops->shutdown(chan);
 409
 410         /* The queued TX requests are simply aborted, no callbacks are made */
 411         spin_lock_irqsave(&chan->lock, flags);
 412         chan->cl = NULL;
 413         chan->active_req = NULL;
 414         if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
 415                 chan->txdone_method = TXDONE_BY_POLL;
 416
 417         module_put(chan->mbox->dev->driver->owner);
 418         spin_unlock_irqrestore(&chan->lock, flags);
 419 }
 420 EXPORT_SYMBOL_GPL(mbox_free_channel);
 421
 422 static struct mbox_chan *
 423 of_mbox_index_xlate(struct mbox_controller *mbox,
 424                     const struct of_phandle_args *sp)
 425 {
 426         int ind = sp->args[0];
 427
 428         if (ind >= mbox->num_chans)
 429                 return ERR_PTR(-EINVAL);
 430
 431         return &mbox->chans[ind];
 432 }
 433
 434 /**
 435  * mbox_controller_register - Register the mailbox controller
 436  * @mbox:       Pointer to the mailbox controller.
 437  *
 438  * The controller driver registers its communication channels
 439  */
 440 int mbox_controller_register(struct mbox_controller *mbox)
 441 {
 442         int i, txdone;
 443
 444         /* Sanity check */
 445         if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
 446                 return -EINVAL;
 447
 448         if (mbox->txdone_irq)
 449                 txdone = TXDONE_BY_IRQ;
 450         else if (mbox->txdone_poll)
 451                 txdone = TXDONE_BY_POLL;
 452         else /* It has to be ACK then */
 453                 txdone = TXDONE_BY_ACK;
 454
 455         if (txdone == TXDONE_BY_POLL) {
 456                 hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
 457                              HRTIMER_MODE_REL);
 458                 mbox->poll_hrt.function = txdone_hrtimer;
 459         }
 460
 461         for (i = 0; i < mbox->num_chans; i++) {
 462                 struct mbox_chan *chan = &mbox->chans[i];
 463
 464                 chan->cl = NULL;
 465                 chan->mbox = mbox;
 466                 chan->txdone_method = txdone;
 467                 spin_lock_init(&chan->lock);
 468         }
 469
 470         if (!mbox->of_xlate)
 471                 mbox->of_xlate = of_mbox_index_xlate;
 472
 473         mutex_lock(&con_mutex);
 474         list_add_tail(&mbox->node, &mbox_cons);
 475         mutex_unlock(&con_mutex);
 476
 477         return 0;
 478 }
 479 EXPORT_SYMBOL_GPL(mbox_controller_register);
 480
 481 /**
 482  * mbox_controller_unregister - Unregister the mailbox controller
 483  * @mbox:       Pointer to the mailbox controller.
 484  */
 485 void mbox_controller_unregister(struct mbox_controller *mbox)
 486 {
 487         int i;
 488
 489         if (!mbox)
 490                 return;
 491
 492         mutex_lock(&con_mutex);
 493
 494         list_del(&mbox->node);
 495
 496         for (i = 0; i < mbox->num_chans; i++)
 497                 mbox_free_channel(&mbox->chans[i]);
 498
 499         if (mbox->txdone_poll)
 500                 hrtimer_cancel(&mbox->poll_hrt);
 501
 502         mutex_unlock(&con_mutex);
 503 }
 504 EXPORT_SYMBOL_GPL(mbox_controller_unregister);