drivers/mailbox/mailbox.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Mailbox: Common code for Mailbox controllers and users
0004  *
0005  * Copyright (C) 2013-2014 Linaro Ltd.
0006  * Author: Jassi Brar <jassisinghbrar@gmail.com>
0007  */
0008
0009 #include <linux/interrupt.h>
0010 #include <linux/spinlock.h>
0011 #include <linux/mutex.h>
0012 #include <linux/delay.h>
0013 #include <linux/slab.h>
0014 #include <linux/err.h>
0015 #include <linux/module.h>
0016 #include <linux/device.h>
0017 #include <linux/bitops.h>
0018 #include <linux/mailbox_client.h>
0019 #include <linux/mailbox_controller.h>
0020
0021 #include "mailbox.h"
0022
0023 static LIST_HEAD(mbox_cons);
0024 static DEFINE_MUTEX(con_mutex);
0025
0026 static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
0027 {
0028     int idx;
0029     unsigned long flags;
0030
0031     spin_lock_irqsave(&chan->lock, flags);
0032
0033     /* See if there is any space left */
0034     if (chan->msg_count == MBOX_TX_QUEUE_LEN) {
0035         spin_unlock_irqrestore(&chan->lock, flags);
0036         return -ENOBUFS;
0037     }
0038
0039     idx = chan->msg_free;
0040     chan->msg_data[idx] = mssg;
0041     chan->msg_count++;
0042
0043     if (idx == MBOX_TX_QUEUE_LEN - 1)
0044         chan->msg_free = 0;
0045     else
0046         chan->msg_free++;
0047
0048     spin_unlock_irqrestore(&chan->lock, flags);
0049
0050     return idx;
0051 }
0052
0053 static void msg_submit(struct mbox_chan *chan)
0054 {
0055     unsigned count, idx;
0056     unsigned long flags;
0057     void *data;
0058     int err = -EBUSY;
0059
0060     spin_lock_irqsave(&chan->lock, flags);
0061
0062     if (!chan->msg_count || chan->active_req)
0063         goto exit;
0064
0065     count = chan->msg_count;
0066     idx = chan->msg_free;
0067     if (idx >= count)
0068         idx -= count;
0069     else
0070         idx += MBOX_TX_QUEUE_LEN - count;
0071
0072     data = chan->msg_data[idx];
0073
0074     if (chan->cl->tx_prepare)
0075         chan->cl->tx_prepare(chan->cl, data);
0076     /* Try to submit a message to the MBOX controller */
0077     err = chan->mbox->ops->send_data(chan, data);
0078     if (!err) {
0079         chan->active_req = data;
0080         chan->msg_count--;
0081     }
0082 exit:
0083     spin_unlock_irqrestore(&chan->lock, flags);
0084
0085     if (!err && (chan->txdone_method & TXDONE_BY_POLL)) {
0086         /* kick start the timer immediately to avoid delays */
0087         spin_lock_irqsave(&chan->mbox->poll_hrt_lock, flags);
0088         hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
0089         spin_unlock_irqrestore(&chan->mbox->poll_hrt_lock, flags);
0090     }
0091 }
0092
0093 static void tx_tick(struct mbox_chan *chan, int r)
0094 {
0095     unsigned long flags;
0096     void *mssg;
0097
0098     spin_lock_irqsave(&chan->lock, flags);
0099     mssg = chan->active_req;
0100     chan->active_req = NULL;
0101     spin_unlock_irqrestore(&chan->lock, flags);
0102
0103     /* Submit next message */
0104     msg_submit(chan);
0105
0106     if (!mssg)
0107         return;
0108
0109     /* Notify the client */
0110     if (chan->cl->tx_done)
0111         chan->cl->tx_done(chan->cl, mssg, r);
0112
0113     if (r != -ETIME && chan->cl->tx_block)
0114         complete(&chan->tx_complete);
0115 }
0116
0117 static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
0118 {
0119     struct mbox_controller *mbox =
0120         container_of(hrtimer, struct mbox_controller, poll_hrt);
0121     bool txdone, resched = false;
0122     int i;
0123     unsigned long flags;
0124
0125     for (i = 0; i < mbox->num_chans; i++) {
0126         struct mbox_chan *chan = &mbox->chans[i];
0127
0128         if (chan->active_req && chan->cl) {
0129             txdone = chan->mbox->ops->last_tx_done(chan);
0130             if (txdone)
0131                 tx_tick(chan, 0);
0132             else
0133                 resched = true;
0134         }
0135     }
0136
0137     if (resched) {
0138         spin_lock_irqsave(&mbox->poll_hrt_lock, flags);
0139         if (!hrtimer_is_queued(hrtimer))
0140             hrtimer_forward_now(hrtimer, ms_to_ktime(mbox->txpoll_period));
0141         spin_unlock_irqrestore(&mbox->poll_hrt_lock, flags);
0142
0143         return HRTIMER_RESTART;
0144     }
0145     return HRTIMER_NORESTART;
0146 }
0147
0148 /**
0149  * mbox_chan_received_data - A way for controller driver to push data
0150  *              received from remote to the upper layer.
0151  * @chan: Pointer to the mailbox channel on which RX happened.
0152  * @mssg: Client specific message typecasted as void *
0153  *
0154  * After startup and before shutdown any data received on the chan
0155  * is passed on to the API via atomic mbox_chan_received_data().
0156  * The controller should ACK the RX only after this call returns.
0157  */
0158 void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
0159 {
0160     /* No buffering the received data */
0161     if (chan->cl->rx_callback)
0162         chan->cl->rx_callback(chan->cl, mssg);
0163 }
0164 EXPORT_SYMBOL_GPL(mbox_chan_received_data);
0165
0166 /**
0167  * mbox_chan_txdone - A way for controller driver to notify the
0168  *          framework that the last TX has completed.
0169  * @chan: Pointer to the mailbox chan on which TX happened.
0170  * @r: Status of last TX - OK or ERROR
0171  *
0172  * The controller that has IRQ for TX ACK calls this atomic API
0173  * to tick the TX state machine. It works only if txdone_irq
0174  * is set by the controller.
0175  */
0176 void mbox_chan_txdone(struct mbox_chan *chan, int r)
0177 {
0178     if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
0179         dev_err(chan->mbox->dev,
0180                "Controller can't run the TX ticker\n");
0181         return;
0182     }
0183
0184     tx_tick(chan, r);
0185 }
0186 EXPORT_SYMBOL_GPL(mbox_chan_txdone);
0187
0188 /**
0189  * mbox_client_txdone - The way for a client to run the TX state machine.
0190  * @chan: Mailbox channel assigned to this client.
0191  * @r: Success status of last transmission.
0192  *
0193  * The client/protocol had received some 'ACK' packet and it notifies
0194  * the API that the last packet was sent successfully. This only works
0195  * if the controller can't sense TX-Done.
0196  */
0197 void mbox_client_txdone(struct mbox_chan *chan, int r)
0198 {
0199     if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
0200         dev_err(chan->mbox->dev, "Client can't run the TX ticker\n");
0201         return;
0202     }
0203
0204     tx_tick(chan, r);
0205 }
0206 EXPORT_SYMBOL_GPL(mbox_client_txdone);
0207
0208 /**
0209  * mbox_client_peek_data - A way for client driver to pull data
0210  *          received from remote by the controller.
0211  * @chan: Mailbox channel assigned to this client.
0212  *
0213  * A poke to controller driver for any received data.
0214  * The data is actually passed onto client via the
0215  * mbox_chan_received_data()
0216  * The call can be made from atomic context, so the controller's
0217  * implementation of peek_data() must not sleep.
0218  *
0219  * Return: True, if controller has, and is going to push after this,
0220  *          some data.
0221  *         False, if controller doesn't have any data to be read.
0222  */
0223 bool mbox_client_peek_data(struct mbox_chan *chan)
0224 {
0225     if (chan->mbox->ops->peek_data)
0226         return chan->mbox->ops->peek_data(chan);
0227
0228     return false;
0229 }
0230 EXPORT_SYMBOL_GPL(mbox_client_peek_data);
0231
0232 /**
0233  * mbox_send_message -  For client to submit a message to be
0234  *              sent to the remote.
0235  * @chan: Mailbox channel assigned to this client.
0236  * @mssg: Client specific message typecasted.
0237  *
0238  * For client to submit data to the controller destined for a remote
0239  * processor. If the client had set 'tx_block', the call will return
0240  * either when the remote receives the data or when 'tx_tout' millisecs
0241  * run out.
0242  *  In non-blocking mode, the requests are buffered by the API and a
0243  * non-negative token is returned for each queued request. If the request
0244  * is not queued, a negative token is returned. Upon failure or successful
0245  * TX, the API calls 'tx_done' from atomic context, from which the client
0246  * could submit yet another request.
0247  * The pointer to message should be preserved until it is sent
0248  * over the chan, i.e, tx_done() is made.
0249  * This function could be called from atomic context as it simply
0250  * queues the data and returns a token against the request.
0251  *
0252  * Return: Non-negative integer for successful submission (non-blocking mode)
0253  *  or transmission over chan (blocking mode).
0254  *  Negative value denotes failure.
0255  */
0256 int mbox_send_message(struct mbox_chan *chan, void *mssg)
0257 {
0258     int t;
0259
0260     if (!chan || !chan->cl)
0261         return -EINVAL;
0262
0263     t = add_to_rbuf(chan, mssg);
0264     if (t < 0) {
0265         dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
0266         return t;
0267     }
0268
0269     msg_submit(chan);
0270
0271     if (chan->cl->tx_block) {
0272         unsigned long wait;
0273         int ret;
0274
0275         if (!chan->cl->tx_tout) /* wait forever */
0276             wait = msecs_to_jiffies(3600000);
0277         else
0278             wait = msecs_to_jiffies(chan->cl->tx_tout);
0279
0280         ret = wait_for_completion_timeout(&chan->tx_complete, wait);
0281         if (ret == 0) {
0282             t = -ETIME;
0283             tx_tick(chan, t);
0284         }
0285     }
0286
0287     return t;
0288 }
0289 EXPORT_SYMBOL_GPL(mbox_send_message);
0290
0291 /**
0292  * mbox_flush - flush a mailbox channel
0293  * @chan: mailbox channel to flush
0294  * @timeout: time, in milliseconds, to allow the flush operation to succeed
0295  *
0296  * Mailbox controllers that need to work in atomic context can implement the
0297  * ->flush() callback to busy loop until a transmission has been completed.
0298  * The implementation must call mbox_chan_txdone() upon success. Clients can
0299  * call the mbox_flush() function at any time after mbox_send_message() to
0300  * flush the transmission. After the function returns success, the mailbox
0301  * transmission is guaranteed to have completed.
0302  *
0303  * Returns: 0 on success or a negative error code on failure.
0304  */
0305 int mbox_flush(struct mbox_chan *chan, unsigned long timeout)
0306 {
0307     int ret;
0308
0309     if (!chan->mbox->ops->flush)
0310         return -ENOTSUPP;
0311
0312     ret = chan->mbox->ops->flush(chan, timeout);
0313     if (ret < 0)
0314         tx_tick(chan, ret);
0315
0316     return ret;
0317 }
0318 EXPORT_SYMBOL_GPL(mbox_flush);
0319
0320 /**
0321  * mbox_request_channel - Request a mailbox channel.
0322  * @cl: Identity of the client requesting the channel.
0323  * @index: Index of mailbox specifier in 'mboxes' property.
0324  *
0325  * The Client specifies its requirements and capabilities while asking for
0326  * a mailbox channel. It can't be called from atomic context.
0327  * The channel is exclusively allocated and can't be used by another
0328  * client before the owner calls mbox_free_channel.
0329  * After assignment, any packet received on this channel will be
0330  * handed over to the client via the 'rx_callback'.
0331  * The framework holds reference to the client, so the mbox_client
0332  * structure shouldn't be modified until the mbox_free_channel returns.
0333  *
0334  * Return: Pointer to the channel assigned to the client if successful.
0335  *      ERR_PTR for request failure.
0336  */
0337 struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
0338 {
0339     struct device *dev = cl->dev;
0340     struct mbox_controller *mbox;
0341     struct of_phandle_args spec;
0342     struct mbox_chan *chan;
0343     unsigned long flags;
0344     int ret;
0345
0346     if (!dev || !dev->of_node) {
0347         pr_debug("%s: No owner device node\n", __func__);
0348         return ERR_PTR(-ENODEV);
0349     }
0350
0351     mutex_lock(&con_mutex);
0352
0353     if (of_parse_phandle_with_args(dev->of_node, "mboxes",
0354                        "#mbox-cells", index, &spec)) {
0355         dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
0356         mutex_unlock(&con_mutex);
0357         return ERR_PTR(-ENODEV);
0358     }
0359
0360     chan = ERR_PTR(-EPROBE_DEFER);
0361     list_for_each_entry(mbox, &mbox_cons, node)
0362         if (mbox->dev->of_node == spec.np) {
0363             chan = mbox->of_xlate(mbox, &spec);
0364             if (!IS_ERR(chan))
0365                 break;
0366         }
0367
0368     of_node_put(spec.np);
0369
0370     if (IS_ERR(chan)) {
0371         mutex_unlock(&con_mutex);
0372         return chan;
0373     }
0374
0375     if (chan->cl || !try_module_get(mbox->dev->driver->owner)) {
0376         dev_dbg(dev, "%s: mailbox not free\n", __func__);
0377         mutex_unlock(&con_mutex);
0378         return ERR_PTR(-EBUSY);
0379     }
0380
0381     spin_lock_irqsave(&chan->lock, flags);
0382     chan->msg_free = 0;
0383     chan->msg_count = 0;
0384     chan->active_req = NULL;
0385     chan->cl = cl;
0386     init_completion(&chan->tx_complete);
0387
0388     if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
0389         chan->txdone_method = TXDONE_BY_ACK;
0390
0391     spin_unlock_irqrestore(&chan->lock, flags);
0392
0393     if (chan->mbox->ops->startup) {
0394         ret = chan->mbox->ops->startup(chan);
0395
0396         if (ret) {
0397             dev_err(dev, "Unable to startup the chan (%d)\n", ret);
0398             mbox_free_channel(chan);
0399             chan = ERR_PTR(ret);
0400         }
0401     }
0402
0403     mutex_unlock(&con_mutex);
0404     return chan;
0405 }
0406 EXPORT_SYMBOL_GPL(mbox_request_channel);
0407
0408 struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
0409                           const char *name)
0410 {
0411     struct device_node *np = cl->dev->of_node;
0412     struct property *prop;
0413     const char *mbox_name;
0414     int index = 0;
0415
0416     if (!np) {
0417         dev_err(cl->dev, "%s() currently only supports DT\n", __func__);
0418         return ERR_PTR(-EINVAL);
0419     }
0420
0421     if (!of_get_property(np, "mbox-names", NULL)) {
0422         dev_err(cl->dev,
0423             "%s() requires an \"mbox-names\" property\n", __func__);
0424         return ERR_PTR(-EINVAL);
0425     }
0426
0427     of_property_for_each_string(np, "mbox-names", prop, mbox_name) {
0428         if (!strncmp(name, mbox_name, strlen(name)))
0429             return mbox_request_channel(cl, index);
0430         index++;
0431     }
0432
0433     dev_err(cl->dev, "%s() could not locate channel named \"%s\"\n",
0434         __func__, name);
0435     return ERR_PTR(-EINVAL);
0436 }
0437 EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
0438
0439 /**
0440  * mbox_free_channel - The client relinquishes control of a mailbox
0441  *          channel by this call.
0442  * @chan: The mailbox channel to be freed.
0443  */
0444 void mbox_free_channel(struct mbox_chan *chan)
0445 {
0446     unsigned long flags;
0447
0448     if (!chan || !chan->cl)
0449         return;
0450
0451     if (chan->mbox->ops->shutdown)
0452         chan->mbox->ops->shutdown(chan);
0453
0454     /* The queued TX requests are simply aborted, no callbacks are made */
0455     spin_lock_irqsave(&chan->lock, flags);
0456     chan->cl = NULL;
0457     chan->active_req = NULL;
0458     if (chan->txdone_method == TXDONE_BY_ACK)
0459         chan->txdone_method = TXDONE_BY_POLL;
0460
0461     module_put(chan->mbox->dev->driver->owner);
0462     spin_unlock_irqrestore(&chan->lock, flags);
0463 }
0464 EXPORT_SYMBOL_GPL(mbox_free_channel);
0465
0466 static struct mbox_chan *
0467 of_mbox_index_xlate(struct mbox_controller *mbox,
0468             const struct of_phandle_args *sp)
0469 {
0470     int ind = sp->args[0];
0471
0472     if (ind >= mbox->num_chans)
0473         return ERR_PTR(-EINVAL);
0474
0475     return &mbox->chans[ind];
0476 }
0477
0478 /**
0479  * mbox_controller_register - Register the mailbox controller
0480  * @mbox:   Pointer to the mailbox controller.
0481  *
0482  * The controller driver registers its communication channels
0483  */
0484 int mbox_controller_register(struct mbox_controller *mbox)
0485 {
0486     int i, txdone;
0487
0488     /* Sanity check */
0489     if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
0490         return -EINVAL;
0491
0492     if (mbox->txdone_irq)
0493         txdone = TXDONE_BY_IRQ;
0494     else if (mbox->txdone_poll)
0495         txdone = TXDONE_BY_POLL;
0496     else /* It has to be ACK then */
0497         txdone = TXDONE_BY_ACK;
0498
0499     if (txdone == TXDONE_BY_POLL) {
0500
0501         if (!mbox->ops->last_tx_done) {
0502             dev_err(mbox->dev, "last_tx_done method is absent\n");
0503             return -EINVAL;
0504         }
0505
0506         hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
0507                  HRTIMER_MODE_REL);
0508         mbox->poll_hrt.function = txdone_hrtimer;
0509         spin_lock_init(&mbox->poll_hrt_lock);
0510     }
0511
0512     for (i = 0; i < mbox->num_chans; i++) {
0513         struct mbox_chan *chan = &mbox->chans[i];
0514
0515         chan->cl = NULL;
0516         chan->mbox = mbox;
0517         chan->txdone_method = txdone;
0518         spin_lock_init(&chan->lock);
0519     }
0520
0521     if (!mbox->of_xlate)
0522         mbox->of_xlate = of_mbox_index_xlate;
0523
0524     mutex_lock(&con_mutex);
0525     list_add_tail(&mbox->node, &mbox_cons);
0526     mutex_unlock(&con_mutex);
0527
0528     return 0;
0529 }
0530 EXPORT_SYMBOL_GPL(mbox_controller_register);
0531
0532 /**
0533  * mbox_controller_unregister - Unregister the mailbox controller
0534  * @mbox:   Pointer to the mailbox controller.
0535  */
0536 void mbox_controller_unregister(struct mbox_controller *mbox)
0537 {
0538     int i;
0539
0540     if (!mbox)
0541         return;
0542
0543     mutex_lock(&con_mutex);
0544
0545     list_del(&mbox->node);
0546
0547     for (i = 0; i < mbox->num_chans; i++)
0548         mbox_free_channel(&mbox->chans[i]);
0549
0550     if (mbox->txdone_poll)
0551         hrtimer_cancel(&mbox->poll_hrt);
0552
0553     mutex_unlock(&con_mutex);
0554 }
0555 EXPORT_SYMBOL_GPL(mbox_controller_unregister);
0556
0557 static void __devm_mbox_controller_unregister(struct device *dev, void *res)
0558 {
0559     struct mbox_controller **mbox = res;
0560
0561     mbox_controller_unregister(*mbox);
0562 }
0563
0564 static int devm_mbox_controller_match(struct device *dev, void *res, void *data)
0565 {
0566     struct mbox_controller **mbox = res;
0567
0568     if (WARN_ON(!mbox || !*mbox))
0569         return 0;
0570
0571     return *mbox == data;
0572 }
0573
0574 /**
0575  * devm_mbox_controller_register() - managed mbox_controller_register()
0576  * @dev: device owning the mailbox controller being registered
0577  * @mbox: mailbox controller being registered
0578  *
0579  * This function adds a device-managed resource that will make sure that the
0580  * mailbox controller, which is registered using mbox_controller_register()
0581  * as part of this function, will be unregistered along with the rest of
0582  * device-managed resources upon driver probe failure or driver removal.
0583  *
0584  * Returns 0 on success or a negative error code on failure.
0585  */
0586 int devm_mbox_controller_register(struct device *dev,
0587                   struct mbox_controller *mbox)
0588 {
0589     struct mbox_controller **ptr;
0590     int err;
0591
0592     ptr = devres_alloc(__devm_mbox_controller_unregister, sizeof(*ptr),
0593                GFP_KERNEL);
0594     if (!ptr)
0595         return -ENOMEM;
0596
0597     err = mbox_controller_register(mbox);
0598     if (err < 0) {
0599         devres_free(ptr);
0600         return err;
0601     }
0602
0603     devres_add(dev, ptr);
0604     *ptr = mbox;
0605
0606     return 0;
0607 }
0608 EXPORT_SYMBOL_GPL(devm_mbox_controller_register);
0609
0610 /**
0611  * devm_mbox_controller_unregister() - managed mbox_controller_unregister()
0612  * @dev: device owning the mailbox controller being unregistered
0613  * @mbox: mailbox controller being unregistered
0614  *
0615  * This function unregisters the mailbox controller and removes the device-
0616  * managed resource that was set up to automatically unregister the mailbox
0617  * controller on driver probe failure or driver removal. It's typically not
0618  * necessary to call this function.
0619  */
0620 void devm_mbox_controller_unregister(struct device *dev, struct mbox_controller *mbox)
0621 {
0622     WARN_ON(devres_release(dev, __devm_mbox_controller_unregister,
0623                    devm_mbox_controller_match, mbox));
0624 }
0625 EXPORT_SYMBOL_GPL(devm_mbox_controller_unregister);