// SPDX-License-Identifier: GPL-2.0-only /* * Mailbox: Common code for Mailbox controllers and users * * Copyright (C) 2013-2014 Linaro Ltd. * Author: Jassi Brar <jassisinghbrar@gmail.com> */ #include <linux/interrupt.h> #include <linux/spinlock.h> #include <linux/mutex.h> #include <linux/delay.h> #include <linux/slab.h> #include <linux/err.h> #include <linux/module.h> #include <linux/device.h> #include <linux/bitops.h> #include <linux/mailbox_client.h> #include <linux/mailbox_controller.h> #include "mailbox.h" static LIST_HEAD(mbox_cons); static DEFINE_MUTEX(con_mutex); static int add_to_rbuf(struct mbox_chan *chan, void *mssg) { int idx; unsigned long flags; spin_lock_irqsave(&chan->lock, flags); /* See if there is any space left */ if (chan->msg_count == MBOX_TX_QUEUE_LEN) { spin_unlock_irqrestore(&chan->lock, flags); return -ENOBUFS; } idx = chan->msg_free; chan->msg_data[idx] = mssg; chan->msg_count++; if (idx == MBOX_TX_QUEUE_LEN - 1) chan->msg_free = 0; else chan->msg_free++; spin_unlock_irqrestore(&chan->lock, flags); return idx; } static void msg_submit(struct mbox_chan *chan) { unsigned count, idx; unsigned long flags; void *data; int err = -EBUSY; spin_lock_irqsave(&chan->lock, flags); if (!chan->msg_count || chan->active_req) goto exit; count = chan->msg_count; idx = chan->msg_free; if (idx >= count) idx -= count; else idx += MBOX_TX_QUEUE_LEN - count; data = chan->msg_data[idx]; if (chan->cl->tx_prepare) chan->cl->tx_prepare(chan->cl, data); /* Try to submit a message to the MBOX controller */ err = chan->mbox->ops->send_data(chan, data); if (!err) { chan->active_req = data; chan->msg_count--; } exit: spin_unlock_irqrestore(&chan->lock, flags); if (!err && (chan->txdone_method & TXDONE_BY_POLL)) /* kick start the timer immediately to avoid delays */ hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL); } static void tx_tick(struct mbox_chan *chan, int r) { unsigned long flags; void *mssg; spin_lock_irqsave(&chan->lock, flags); mssg = chan->active_req; chan->active_req = NULL; spin_unlock_irqrestore(&chan->lock, flags); /* Submit next message */ msg_submit(chan); if (!mssg) return; /* Notify the client */ if (chan->cl->tx_done) chan->cl->tx_done(chan->cl, mssg, r); if (r != -ETIME && chan->cl->tx_block) complete(&chan->tx_complete); } static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer) { struct mbox_controller *mbox = container_of(hrtimer, struct mbox_controller, poll_hrt); bool txdone, resched = false; int i; for (i = 0; i < mbox->num_chans; i++) { struct mbox_chan *chan = &mbox->chans[i]; if (chan->active_req && chan->cl) { txdone = chan->mbox->ops->last_tx_done(chan); if (txdone) tx_tick(chan, 0); else resched = true; } } if (resched) { hrtimer_forward_now(hrtimer, ms_to_ktime(mbox->txpoll_period)); return HRTIMER_RESTART; } return HRTIMER_NORESTART; } /** * mbox_chan_received_data - A way for controller driver to push data * received from remote to the upper layer. * @chan: Pointer to the mailbox channel on which RX happened. * @mssg: Client specific message typecasted as void * * * After startup and before shutdown any data received on the chan * is passed on to the API via atomic mbox_chan_received_data(). * The controller should ACK the RX only after this call returns. */ void mbox_chan_received_data(struct mbox_chan *chan, void *mssg) { /* No buffering the received data */ if (chan->cl->rx_callback) chan->cl->rx_callback(chan->cl, mssg); } EXPORT_SYMBOL_GPL(mbox_chan_received_data); /** * mbox_chan_txdone - A way for controller driver to notify the * framework that the last TX has completed. * @chan: Pointer to the mailbox chan on which TX happened. * @r: Status of last TX - OK or ERROR * * The controller that has IRQ for TX ACK calls this atomic API * to tick the TX state machine. It works only if txdone_irq * is set by the controller. */ void mbox_chan_txdone(struct mbox_chan *chan, int r) { if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) { dev_err(chan->mbox->dev, "Controller can't run the TX ticker\n"); return; } tx_tick(chan, r); } EXPORT_SYMBOL_GPL(mbox_chan_txdone); /** * mbox_client_txdone - The way for a client to run the TX state machine. * @chan: Mailbox channel assigned to this client. * @r: Success status of last transmission. * * The client/protocol had received some 'ACK' packet and it notifies * the API that the last packet was sent successfully. This only works * if the controller can't sense TX-Done. */ void mbox_client_txdone(struct mbox_chan *chan, int r) { if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) { dev_err(chan->mbox->dev, "Client can't run the TX ticker\n"); return; } tx_tick(chan, r); } EXPORT_SYMBOL_GPL(mbox_client_txdone); /** * mbox_client_peek_data - A way for client driver to pull data * received from remote by the controller. * @chan: Mailbox channel assigned to this client. * * A poke to controller driver for any received data. * The data is actually passed onto client via the * mbox_chan_received_data() * The call can be made from atomic context, so the controller's * implementation of peek_data() must not sleep. * * Return: True, if controller has, and is going to push after this, * some data. * False, if controller doesn't have any data to be read. */ bool mbox_client_peek_data(struct mbox_chan *chan) { if (chan->mbox->ops->peek_data) return chan->mbox->ops->peek_data(chan); return false; } EXPORT_SYMBOL_GPL(mbox_client_peek_data); /** * mbox_send_message - For client to submit a message to be * sent to the remote. * @chan: Mailbox channel assigned to this client. * @mssg: Client specific message typecasted. * * For client to submit data to the controller destined for a remote * processor. If the client had set 'tx_block', the call will return * either when the remote receives the data or when 'tx_tout' millisecs * run out. * In non-blocking mode, the requests are buffered by the API and a * non-negative token is returned for each queued request. If the request * is not queued, a negative token is returned. Upon failure or successful * TX, the API calls 'tx_done' from atomic context, from which the client * could submit yet another request. * The pointer to message should be preserved until it is sent * over the chan, i.e, tx_done() is made. * This function could be called from atomic context as it simply * queues the data and returns a token against the request. * * Return: Non-negative integer for successful submission (non-blocking mode) * or transmission over chan (blocking mode). * Negative value denotes failure. */ int mbox_send_message(struct mbox_chan *chan, void *mssg) { int t; if (!chan || !chan->cl) return -EINVAL; t = add_to_rbuf(chan, mssg); if (t < 0) { dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n"); return t; } msg_submit(chan); if (chan->cl->tx_block) { unsigned long wait; int ret; if (!chan->cl->tx_tout) /* wait forever */ wait = msecs_to_jiffies(3600000); else wait = msecs_to_jiffies(chan->cl->tx_tout); ret = wait_for_completion_timeout(&chan->tx_complete, wait); if (ret == 0) { t = -ETIME; tx_tick(chan, t); } } return t; } EXPORT_SYMBOL_GPL(mbox_send_message); /** * mbox_flush - flush a mailbox channel * @chan: mailbox channel to flush * @timeout: time, in milliseconds, to allow the flush operation to succeed * * Mailbox controllers that need to work in atomic context can implement the * ->flush() callback to busy loop until a transmission has been completed. * The implementation must call mbox_chan_txdone() upon success. Clients can * call the mbox_flush() function at any time after mbox_send_message() to * flush the transmission. After the function returns success, the mailbox * transmission is guaranteed to have completed. * * Returns: 0 on success or a negative error code on failure. */ int mbox_flush(struct mbox_chan *chan, unsigned long timeout) { int ret; if (!chan->mbox->ops->flush) return -ENOTSUPP; ret = chan->mbox->ops->flush(chan, timeout); if (ret < 0) tx_tick(chan, ret); return ret; } EXPORT_SYMBOL_GPL(mbox_flush); /** * mbox_request_channel - Request a mailbox channel. * @cl: Identity of the client requesting the channel. * @index: Index of mailbox specifier in 'mboxes' property. * * The Client specifies its requirements and capabilities while asking for * a mailbox channel. It can't be called from atomic context. * The channel is exclusively allocated and can't be used by another * client before the owner calls mbox_free_channel. * After assignment, any packet received on this channel will be * handed over to the client via the 'rx_callback'. * The framework holds reference to the client, so the mbox_client * structure shouldn't be modified until the mbox_free_channel returns. * * Return: Pointer to the channel assigned to the client if successful. * ERR_PTR for request failure. */ struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index) { struct device *dev = cl->dev; struct mbox_controller *mbox; struct of_phandle_args spec; struct mbox_chan *chan; unsigned long flags; int ret; if (!dev || !dev->of_node) { pr_debug("%s: No owner device node\n", __func__); return ERR_PTR(-ENODEV); } mutex_lock(&con_mutex); if (of_parse_phandle_with_args(dev->of_node, "mboxes", "#mbox-cells", index, &spec)) { dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__); mutex_unlock(&con_mutex); return ERR_PTR(-ENODEV); } chan = ERR_PTR(-EPROBE_DEFER); list_for_each_entry(mbox, &mbox_cons, node) if (mbox->dev->of_node == spec.np) { chan = mbox->of_xlate(mbox, &spec); if (!IS_ERR(chan)) break; } of_node_put(spec.np); if (IS_ERR(chan)) { mutex_unlock(&con_mutex); return chan; } if (chan->cl || !try_module_get(mbox->dev->driver->owner)) { dev_dbg(dev, "%s: mailbox not free\n", __func__); mutex_unlock(&con_mutex); return ERR_PTR(-EBUSY); } spin_lock_irqsave(&chan->lock, flags); chan->msg_free = 0; chan->msg_count = 0; chan->active_req = NULL; chan->cl = cl; init_completion(&chan->tx_complete); if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) chan->txdone_method = TXDONE_BY_ACK; spin_unlock_irqrestore(&chan->lock, flags); if (chan->mbox->ops->startup) { ret = chan->mbox->ops->startup(chan); if (ret) { dev_err(dev, "Unable to startup the chan (%d)\n", ret); mbox_free_channel(chan); chan = ERR_PTR(ret); } } mutex_unlock(&con_mutex); return chan; } EXPORT_SYMBOL_GPL(mbox_request_channel); struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl, const char *name) { struct device_node *np = cl->dev->of_node; struct property *prop; const char *mbox_name; int index = 0; if (!np) { dev_err(cl->dev, "%s() currently only supports DT\n", __func__); return ERR_PTR(-EINVAL); } if (!of_get_property(np, "mbox-names", NULL)) { dev_err(cl->dev, "%s() requires an \"mbox-names\" property\n", __func__); return ERR_PTR(-EINVAL); } of_property_for_each_string(np, "mbox-names", prop, mbox_name) { if (!strncmp(name, mbox_name, strlen(name))) return mbox_request_channel(cl, index); index++; } dev_err(cl->dev, "%s() could not locate channel named \"%s\"\n", __func__, name); return ERR_PTR(-EINVAL); } EXPORT_SYMBOL_GPL(mbox_request_channel_byname); /** * mbox_free_channel - The client relinquishes control of a mailbox * channel by this call. * @chan: The mailbox channel to be freed. */ void mbox_free_channel(struct mbox_chan *chan) { unsigned long flags; if (!chan || !chan->cl) return; if (chan->mbox->ops->shutdown) chan->mbox->ops->shutdown(chan); /* The queued TX requests are simply aborted, no callbacks are made */ spin_lock_irqsave(&chan->lock, flags); chan->cl = NULL; chan->active_req = NULL; if (chan->txdone_method == TXDONE_BY_ACK) chan->txdone_method = TXDONE_BY_POLL; module_put(chan->mbox->dev->driver->owner); spin_unlock_irqrestore(&chan->lock, flags); } EXPORT_SYMBOL_GPL(mbox_free_channel); static struct mbox_chan * of_mbox_index_xlate(struct mbox_controller *mbox, const struct of_phandle_args *sp) { int ind = sp->args[0]; if (ind >= mbox->num_chans) return ERR_PTR(-EINVAL); return &mbox->chans[ind]; } /** * mbox_controller_register - Register the mailbox controller * @mbox: Pointer to the mailbox controller. * * The controller driver registers its communication channels */ int mbox_controller_register(struct mbox_controller *mbox) { int i, txdone; /* Sanity check */ if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans) return -EINVAL; if (mbox->txdone_irq) txdone = TXDONE_BY_IRQ; else if (mbox->txdone_poll) txdone = TXDONE_BY_POLL; else /* It has to be ACK then */ txdone = TXDONE_BY_ACK; if (txdone == TXDONE_BY_POLL) { if (!mbox->ops->last_tx_done) { dev_err(mbox->dev, "last_tx_done method is absent\n"); return -EINVAL; } hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL); mbox->poll_hrt.function = txdone_hrtimer; } for (i = 0; i < mbox->num_chans; i++) { struct mbox_chan *chan = &mbox->chans[i]; chan->cl = NULL; chan->mbox = mbox; chan->txdone_method = txdone; spin_lock_init(&chan->lock); } if (!mbox->of_xlate) mbox->of_xlate = of_mbox_index_xlate; mutex_lock(&con_mutex); list_add_tail(&mbox->node, &mbox_cons); mutex_unlock(&con_mutex); return 0; } EXPORT_SYMBOL_GPL(mbox_controller_register); /** * mbox_controller_unregister - Unregister the mailbox controller * @mbox: Pointer to the mailbox controller. */ void mbox_controller_unregister(struct mbox_controller *mbox) { int i; if (!mbox) return; mutex_lock(&con_mutex); list_del(&mbox->node); for (i = 0; i < mbox->num_chans; i++) mbox_free_channel(&mbox->chans[i]); if (mbox->txdone_poll) hrtimer_cancel(&mbox->poll_hrt); mutex_unlock(&con_mutex); } EXPORT_SYMBOL_GPL(mbox_controller_unregister); static void __devm_mbox_controller_unregister(struct device *dev, void *res) { struct mbox_controller **mbox = res; mbox_controller_unregister(*mbox); } static int devm_mbox_controller_match(struct device *dev, void *res, void *data) { struct mbox_controller **mbox = res; if (WARN_ON(!mbox || !*mbox)) return 0; return *mbox == data; } /** * devm_mbox_controller_register() - managed mbox_controller_register() * @dev: device owning the mailbox controller being registered * @mbox: mailbox controller being registered * * This function adds a device-managed resource that will make sure that the * mailbox controller, which is registered using mbox_controller_register() * as part of this function, will be unregistered along with the rest of * device-managed resources upon driver probe failure or driver removal. * * Returns 0 on success or a negative error code on failure. */ int devm_mbox_controller_register(struct device *dev, struct mbox_controller *mbox) { struct mbox_controller **ptr; int err; ptr = devres_alloc(__devm_mbox_controller_unregister, sizeof(*ptr), GFP_KERNEL); if (!ptr) return -ENOMEM; err = mbox_controller_register(mbox); if (err < 0) { devres_free(ptr); return err; } devres_add(dev, ptr); *ptr = mbox; return 0; } EXPORT_SYMBOL_GPL(devm_mbox_controller_register); /** * devm_mbox_controller_unregister() - managed mbox_controller_unregister() * @dev: device owning the mailbox controller being unregistered * @mbox: mailbox controller being unregistered * * This function unregisters the mailbox controller and removes the device- * managed resource that was set up to automatically unregister the mailbox * controller on driver probe failure or driver removal. It's typically not * necessary to call this function. */ void devm_mbox_controller_unregister(struct device *dev, struct mbox_controller *mbox) { WARN_ON(devres_release(dev, __devm_mbox_controller_unregister, devm_mbox_controller_match, mbox)); } EXPORT_SYMBOL_GPL(devm_mbox_controller_unregister);