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SubjectRe: [PATCHv4,2/5] mailbox: Introduce framework for mailbox
Date
> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
> new file mode 100644
> index 0000000..79d576e
> --- /dev/null
> +++ b/drivers/mailbox/mailbox.c
> @@ -0,0 +1,589 @@
> +/*
> + * Mailbox: Common code for Mailbox controllers and users
> + *
> + * Copyright (C) 2014 Linaro Ltd.
> + * Author: Jassi Brar <jassisinghbrar@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#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/mailbox_client.h>
> +#include <linux/mailbox_controller.h>
> +
> +/*
> + * The length of circular buffer for queuing messages from a client.
> + * 'msg_count' tracks the number of buffered messages while 'msg_free'
> + * is the index where the next message would be buffered.
> + * We shouldn't need it too big because every transferr is interrupt
> + * triggered and if we have lots of data to transfer, the interrupt
> + * latencies are going to be the bottleneck, not the buffer length.
> + * Besides, mbox_send_message could be called from atomic context and
> + * the client could also queue another message from the notifier 'tx_done'
> + * of the last transfer done.
> + * REVIST: If too many platforms see the "Try increasing MBOX_TX_QUEUE_LEN"
> + * print, it needs to be taken from config option or somesuch.
> + */
> +#define MBOX_TX_QUEUE_LEN 20
> +
> +#define TXDONE_BY_IRQ (1 << 0) /* controller has remote RTR irq */
> +#define TXDONE_BY_POLL (1 << 1) /* controller can read status of last TX */
> +#define TXDONE_BY_ACK (1 << 2) /* S/W ACK recevied by Client ticks the TX */
> +
> +struct mbox_chan {
> + char name[16]; /* Physical link's name */
> + struct mbox_con *con; /* Parent Controller */
> + unsigned txdone_method;
> +
> + /* Physical links */
> + struct mbox_link *link;
> + struct mbox_link_ops *link_ops;
> +
> + /* client */
> + struct mbox_client *cl;
> + struct completion tx_complete;
> +
> + void *active_req;
> + unsigned msg_count, msg_free;
> + void *msg_data[MBOX_TX_QUEUE_LEN];
> + /* Access to the channel */
> + spinlock_t lock;
> + /* Hook to add to the controller's list of channels */
> + struct list_head node;
> + /* Notifier to all clients waiting on aquiring this channel */
> + struct blocking_notifier_head avail;
> +} __aligned(32);
> +
> +/* Internal representation of a controller */
> +struct mbox_con {
> + struct device *dev;
> + char name[16]; /* controller_name */
> + struct list_head channels;
> + /*
> + * If the controller supports only TXDONE_BY_POLL,
> + * this timer polls all the links for txdone.
> + */
> + struct timer_list poll;
> + unsigned period;
> + /* Hook to add to the global controller list */
> + struct list_head node;
> +} __aligned(32);
> +
> +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 -ENOMEM;
> + }
> +
> + 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)
> +{
> + struct mbox_link *link = chan->link;
> + unsigned count, idx;
> + unsigned long flags;
> + void *data;
> + int err;
> +
> + spin_lock_irqsave(&chan->lock, flags);
> +
> + if (!chan->msg_count || chan->active_req) {
> + spin_unlock_irqrestore(&chan->lock, flags);
> + return;
> + }
> +
> + 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];
> +
> + /* Try to submit a message to the MBOX controller */
> + err = chan->link_ops->send_data(link, data);
> + if (!err) {
> + chan->active_req = data;
> + chan->msg_count--;
> + }
> +
> + spin_unlock_irqrestore(&chan->lock, flags);
> +}
> +
> +static void tx_tick(struct mbox_chan *chan, enum mbox_result 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);
> +
> + /* Notify the client */
> + if (chan->cl->tx_block)
> + complete(&chan->tx_complete);
> + else if (mssg && chan->cl->tx_done)
> + chan->cl->tx_done(chan->cl, mssg, r);
> +}
> +
> +static void poll_txdone(unsigned long data)
> +{
> + struct mbox_con *con = (struct mbox_con *)data;
> + bool txdone, resched = false;
> + struct mbox_chan *chan;
> +
> + list_for_each_entry(chan, &con->channels, node) {
> + if (chan->active_req && chan->cl) {
> + resched = true;
> + txdone = chan->link_ops->last_tx_done(chan->link);
> + if (txdone)
> + tx_tick(chan, MBOX_OK);
> + }
> + }
> +
> + if (resched)
> + mod_timer(&con->poll,
> + jiffies + msecs_to_jiffies(con->period));
> +}
> +
> +/**
> + * mbox_link_received_data - A way for controller driver to push data
> + * received from remote to the upper layer.
> + * @link: Pointer to the mailbox link on which RX happened.
> + * @data: Client specific message typecasted as void *
> + *
> + * After startup and before shutdown any data received on the link
> + * is passed on to the API via atomic mbox_link_received_data().
> + * The controller should ACK the RX only after this call returns.
> + */
> +void mbox_link_received_data(struct mbox_link *link, void *mssg)
> +{
> + struct mbox_chan *chan = (struct mbox_chan *)link->api_priv;
> +
> + /* No buffering the received data */
> + if (chan->cl->rx_callback)
> + chan->cl->rx_callback(chan->cl, mssg);
> +}
> +EXPORT_SYMBOL_GPL(mbox_link_received_data);
> +
> +/**
> + * mbox_link_txdone - A way for controller driver to notify the
> + * framework that the last TX has completed.
> + * @link: Pointer to the mailbox link 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_link_txdone(struct mbox_link *link, enum mbox_result r)
> +{
> + struct mbox_chan *chan = (struct mbox_chan *)link->api_priv;
> +
> + if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
> + pr_err("Controller can't run the TX ticker\n");
> + return;
> + }
> +
> + tx_tick(chan, r);
> +}
> +EXPORT_SYMBOL_GPL(mbox_link_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, enum mbox_result r)
> +{
> + if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
> + pr_err("Client can't run the TX ticker\n");
> + return;
> + }
> +
> + tx_tick(chan, r);
> +}
> +EXPORT_SYMBOL_GPL(mbox_client_txdone);
> +
> +/**
> + * 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.
> + * In blocking mode, 'tx_done' is not called, effectively making the
> + * queue length 1.
> + * The pointer to message should be preserved until it is sent
> + * over the link, 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 link (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) {
> + pr_err("Try increasing MBOX_TX_QUEUE_LEN\n");
> + return t;
> + }
> +
> + _msg_submit(chan);
> +
> + if (chan->txdone_method == TXDONE_BY_POLL)
> + poll_txdone((unsigned long)chan->con);

Wouldn't it be cleaner to use
poll_txdone((unsigned long)&chan->con);
?

> +
> + if (chan->cl->tx_block && chan->active_req) {
> + int ret;
> + init_completion(&chan->tx_complete);
> + ret = wait_for_completion_timeout(&chan->tx_complete,
> + chan->cl->tx_tout);
> + if (ret == 0) {
> + t = -EIO;
> + tx_tick(chan, MBOX_ERR);
> + }
> + }
> +
> + return t;
> +}
> +EXPORT_SYMBOL_GPL(mbox_send_message);
> +
> +/**
> + * mbox_request_channel - Request a mailbox channel.
> + * @cl: Identity of the client requesting the channel.
> + *
> + * The Client specifies its requirements and capabilities while asking for
> + * a mailbox channel by name. 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'.
> + *
> + * 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)
> +{
> + struct mbox_chan *chan;
> + struct mbox_con *con;
> + unsigned long flags;
> + char *con_name;
> + int len, ret;
> +
> + con_name = cl->chan_name;
> + len = strcspn(cl->chan_name, ":");
> +
> + ret = 0;
> + mutex_lock(&con_mutex);
> + list_for_each_entry(con, &mbox_cons, node)
> + if (!strncmp(con->name, con_name, len)) {
> + ret = 1;
> + break;
> + }
> + mutex_unlock(&con_mutex);
> +
> + if (!ret) {
> + pr_info("Channel(%s) not found!\n", cl->chan_name);
> + return ERR_PTR(-ENODEV);
> + }
> +
> + ret = 0;
> + list_for_each_entry(chan, &con->channels, node) {
> + if (!chan->cl &&
> + !strcmp(con_name + len + 1, chan->name) &&
> + try_module_get(con->dev->driver->owner)) {
> + spin_lock_irqsave(&chan->lock, flags);
> + chan->msg_free = 0;
> + chan->msg_count = 0;
> + chan->active_req = NULL;
> + chan->cl = cl;
> + if (!cl->tx_tout) /* wait for ever */
> + cl->tx_tout = msecs_to_jiffies(3600000);
> + else
> + cl->tx_tout = msecs_to_jiffies(cl->tx_tout);
> + if (chan->txdone_method == TXDONE_BY_POLL
> + && cl->knows_txdone)
> + chan->txdone_method |= TXDONE_BY_ACK;
> + spin_unlock_irqrestore(&chan->lock, flags);
> + ret = 1;
> + break;
> + }
> + }
> +
> + if (!ret) {
> + pr_err("Unable to assign mailbox(%s)\n", cl->chan_name);
> + return ERR_PTR(-EBUSY);
> + }
> +
> + ret = chan->link_ops->startup(chan->link, cl->link_data);
> + if (ret) {
> + pr_err("Unable to startup the link\n");
> + mbox_free_channel(chan);
> + return ERR_PTR(ret);
> + }
> +
> + return chan;
> +}
> +EXPORT_SYMBOL_GPL(mbox_request_channel);
> +
> +/**
> + * 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;
> +
> + chan->link_ops->shutdown(chan->link);
> +
> + /* 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_POLL | TXDONE_BY_ACK))
> + chan->txdone_method = TXDONE_BY_POLL;
> +
> + module_put(chan->con->dev->driver->owner);
> +
> + spin_unlock_irqrestore(&chan->lock, flags);
> +
> + blocking_notifier_call_chain(&chan->avail, 0, NULL);
> +}
> +EXPORT_SYMBOL_GPL(mbox_free_channel);
> +
> +static struct mbox_chan *name_to_chan(const char *name)
> +{
> + struct mbox_chan *chan = NULL;
> + struct mbox_con *con;
> + int len, found = 0;
> +
> + len = strcspn(name, ":");
> +
> + mutex_lock(&con_mutex);
> +
> + list_for_each_entry(con, &mbox_cons, node) {
> + if (!strncmp(con->name, name, len)) {
> + list_for_each_entry(chan, &con->channels, node) {
> + if (!strcmp(name + len + 1, chan->name)) {
> + found = 1;
> + goto done;
> + }
> + }
> + }
> + }
> +done:
> + mutex_unlock(&con_mutex);
> +
> + if (!found)
> + return NULL;
> +
> + return chan;
> +}
> +
> +/**
> + * mbox_notify_chan_register - The client may ask the framework to be
> + * notified when a particular channel becomes available
> + * to be acquired again.
> + * @name: Name of the mailbox channel the client is interested in.
> + * @nb: Pointer to the notifier.
> + */
> +int mbox_notify_chan_register(const char *name, struct notifier_block *nb)
> +{
> + struct mbox_chan *chan = name_to_chan(name);
> +
> + if (chan && nb)
> + return blocking_notifier_chain_register(&chan->avail, nb);
> +
> + return -EINVAL;
> +}
> +EXPORT_SYMBOL_GPL(mbox_notify_chan_register);
> +
> +/**
> + * mbox_notify_chan_unregister - The client is no more interested in channel.
> + *
> + * @name: Name of the mailbox channel the client was interested in.
> + * @nb: Pointer to the notifier.
> + */
> +void mbox_notify_chan_unregister(const char *name, struct notifier_block *nb)
> +{
> + struct mbox_chan *chan = name_to_chan(name);
> +
> + if (chan && nb)
> + blocking_notifier_chain_unregister(&chan->avail, nb);
> +}
> +EXPORT_SYMBOL_GPL(mbox_notify_chan_unregister);
> +
> +/**
> + * mbox_controller_register - Register the mailbox controller
> + * @mbox_con: Pointer to the mailbox controller.
> + *
> + * The controller driver registers its communication links to the
> + * global pool managed by the common framework.
> + */
> +int mbox_controller_register(struct mbox_controller *mbox)
> +{
> + int i, num_links, txdone;
> + struct mbox_chan *chan;
> + struct mbox_con *con;
> +
> + /* Sanity check */
> + if (!mbox || !mbox->ops)
> + return -EINVAL;
> +
> + for (i = 0; mbox->links[i]; i++)
> + ;
> + if (!i)
> + return -EINVAL;
> + num_links = i;
> +
> + mutex_lock(&con_mutex);
> + /* Check if already populated */
> + list_for_each_entry(con, &mbox_cons, node)
> + if (!strcmp(mbox->controller_name, con->name)) {
> + mutex_unlock(&con_mutex);
> + return -EINVAL;
> + }
> +
> + con = kzalloc(sizeof(struct mbox_con), GFP_KERNEL);
> + if (!con)
> + return -ENOMEM;

The mutex is not freed here.

> +
> + chan = kzalloc(sizeof(struct mbox_chan) * num_links, GFP_KERNEL);
> + if (!chan) {
> + kfree(con);
> + return -ENOMEM;

Again, the mutex is not freed.

You could move both allocations above the mutex. Then you won't have to
worry about it.

> + }
> +
> + con->dev = mbox->dev;
> + INIT_LIST_HEAD(&con->channels);
> + snprintf(con->name, 16, "%s", mbox->controller_name);
> +
> + 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) {
> + con->period = mbox->txpoll_period;
> + con->poll.function = &poll_txdone;
> + con->poll.data = (unsigned long)con;

How about
con->poll.data = (unsigned long)&con;

> + init_timer(&con->poll);
> + }
> +
> + for (i = 0; i < num_links; i++) {
> + chan[i].con = con;
> + chan[i].cl = NULL;
> + chan[i].link_ops = mbox->ops;
> + chan[i].link = mbox->links[i];
> + chan[i].txdone_method = txdone;
> + chan[i].link->api_priv = &chan[i];
> + spin_lock_init(&chan[i].lock);
> + BLOCKING_INIT_NOTIFIER_HEAD(&chan[i].avail);
> + list_add_tail(&chan[i].node, &con->channels);
> + snprintf(chan[i].name, 16, "%s", mbox->links[i]->link_name);
> + }
> +
> + list_add_tail(&con->node, &mbox_cons);
> + mutex_unlock(&con_mutex);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(mbox_controller_register);
> +
> +/**
> + * mbox_controller_unregister - UnRegister the mailbox controller
> + * @mbox_con: Pointer to the mailbox controller.
> + *
> + * Purge the mailbox links from the global pool maintained by the framework.
> + */
> +void mbox_controller_unregister(struct mbox_controller *mbox)
> +{
> + struct mbox_con *t, *con = NULL;
> + struct mbox_chan *chan;
> +
> + mutex_lock(&con_mutex);
> +
> + list_for_each_entry(t, &mbox_cons, node)
> + if (!strcmp(mbox->controller_name, t->name)) {
> + con = t;
> + break;
> + }
> +
> + if (con)
> + list_del(&con->node);
> +
> + mutex_unlock(&con_mutex);
> +
> + if (!con)
> + return;
> +
> + list_for_each_entry(chan, &con->channels, node)
> + mbox_free_channel(chan);
> +
> + del_timer_sync(&con->poll);
> +
> + kfree(con);
> +}
> +EXPORT_SYMBOL_GPL(mbox_controller_unregister);

Regards,
-Markus


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