[linux-2.6-block.git] / drivers / mailbox / mailbox.c

/*
 * Mailbox: Common code for Mailbox controllers and users
 *
 * Copyright (C) 2013-2014 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/bitops.h>
#include <linux/mailbox_client.h>
#include <linux/mailbox_controller.h>

#define TXDONE_BY_IRQ	BIT(0) /* controller has remote RTR irq */
#define TXDONE_BY_POLL	BIT(1) /* controller can read status of last TX */
#define TXDONE_BY_ACK	BIT(2) /* S/W ACK recevied by Client ticks the TX */

static LIST_HEAD(mbox_cons);
static DEFINE_MUTEX(con_mutex);

static void poll_txdone(unsigned long data);

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];

	/* 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)
		poll_txdone((unsigned long)chan->mbox);
}

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);

	/* Notify the client */
	if (mssg && chan->cl->tx_done)
		chan->cl->tx_done(chan->cl, mssg, r);

	if (chan->cl->tx_block)
		complete(&chan->tx_complete);
}

static void poll_txdone(unsigned long data)
{
	struct mbox_controller *mbox = (struct mbox_controller *)data;
	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)
		mod_timer(&mbox->poll, jiffies +
				msecs_to_jiffies(mbox->txpoll_period));
}

/**
 * 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 && chan->active_req) {
		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 = -EIO;
			tx_tick(chan, -EIO);
		}
	}

	return t;
}
EXPORT_SYMBOL_GPL(mbox_send_message);

/**
 * 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 = NULL;
	list_for_each_entry(mbox, &mbox_cons, node)
		if (mbox->dev->of_node == spec.np) {
			chan = mbox->of_xlate(mbox, &spec);
			break;
		}

	of_node_put(spec.np);

	if (!chan || 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);

	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);

/**
 * 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->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_POLL | 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 NULL;

	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) {
		mbox->poll.function = &poll_txdone;
		mbox->poll.data = (unsigned long)mbox;
		init_timer(&mbox->poll);
	}

	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)
		del_timer_sync(&mbox->poll);

	mutex_unlock(&con_mutex);
}
EXPORT_SYMBOL_GPL(mbox_controller_unregister);
Commit	Line	Data
2b6d83e2 JB	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	#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */
	25	#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */
	26	#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */
	27
	28	static LIST_HEAD(mbox_cons);
	29	static DEFINE_MUTEX(con_mutex);
	30
52a49306 AB	31	static void poll_txdone(unsigned long data);
52a49306 AB	32
2b6d83e2 JB	33	static int add_to_rbuf(struct mbox_chan chan, void mssg)
	34	{
	35	int idx;
	36	unsigned long flags;
	37
	38	spin_lock_irqsave(&chan->lock, flags);
	39
	40	/* See if there is any space left */
	41	if (chan->msg_count == MBOX_TX_QUEUE_LEN) {
	42	spin_unlock_irqrestore(&chan->lock, flags);
	43	return -ENOBUFS;
	44	}
	45
	46	idx = chan->msg_free;
	47	chan->msg_data[idx] = mssg;
	48	chan->msg_count++;
	49
	50	if (idx == MBOX_TX_QUEUE_LEN - 1)
	51	chan->msg_free = 0;
	52	else
	53	chan->msg_free++;
	54
	55	spin_unlock_irqrestore(&chan->lock, flags);
	56
	57	return idx;
	58	}
	59
	60	static void msg_submit(struct mbox_chan *chan)
	61	{
	62	unsigned count, idx;
	63	unsigned long flags;
	64	void *data;
52a49306	65	int err = -EBUSY;
2b6d83e2 JB	66
	67	spin_lock_irqsave(&chan->lock, flags);
	68
	69	if (!chan->msg_count \|\| chan->active_req)
	70	goto exit;
	71
	72	count = chan->msg_count;
	73	idx = chan->msg_free;
	74	if (idx >= count)
	75	idx -= count;
	76	else
	77	idx += MBOX_TX_QUEUE_LEN - count;
	78
	79	data = chan->msg_data[idx];
	80
	81	/* Try to submit a message to the MBOX controller */
	82	err = chan->mbox->ops->send_data(chan, data);
	83	if (!err) {
	84	chan->active_req = data;
	85	chan->msg_count--;
	86	}
	87	exit:
	88	spin_unlock_irqrestore(&chan->lock, flags);
52a49306 AB	89
	90	if (!err && chan->txdone_method == TXDONE_BY_POLL)
	91	poll_txdone((unsigned long)chan->mbox);
2b6d83e2 JB	92	}
	93
	94	static void tx_tick(struct mbox_chan *chan, int r)
	95	{
	96	unsigned long flags;
	97	void *mssg;
	98
	99	spin_lock_irqsave(&chan->lock, flags);
	100	mssg = chan->active_req;
	101	chan->active_req = NULL;
	102	spin_unlock_irqrestore(&chan->lock, flags);
	103
	104	/* Submit next message */
	105	msg_submit(chan);
	106
	107	/* Notify the client */
	108	if (mssg && chan->cl->tx_done)
	109	chan->cl->tx_done(chan->cl, mssg, r);
	110
	111	if (chan->cl->tx_block)
	112	complete(&chan->tx_complete);
	113	}
	114
	115	static void poll_txdone(unsigned long data)
	116	{
	117	struct mbox_controller mbox = (struct mbox_controller )data;
	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) {
2b6d83e2 JB	125	txdone = chan->mbox->ops->last_tx_done(chan);
	126	if (txdone)
	127	tx_tick(chan, 0);
52a49306 AB	128	else
52a49306 AB	129	resched = true;
2b6d83e2 JB	130	}
	131	}
	132
	133	if (resched)
	134	mod_timer(&mbox->poll, jiffies +
	135	msecs_to_jiffies(mbox->txpoll_period));
	136	}
	137
	138	/**
	139	* mbox_chan_received_data - A way for controller driver to push data
	140	* received from remote to the upper layer.
	141	* @chan: Pointer to the mailbox channel on which RX happened.
	142	* @mssg: Client specific message typecasted as void *
	143	*
	144	* After startup and before shutdown any data received on the chan
	145	* is passed on to the API via atomic mbox_chan_received_data().
	146	* The controller should ACK the RX only after this call returns.
	147	*/
	148	void mbox_chan_received_data(struct mbox_chan chan, void mssg)
	149	{
	150	/* No buffering the received data */
	151	if (chan->cl->rx_callback)
	152	chan->cl->rx_callback(chan->cl, mssg);
	153	}
	154	EXPORT_SYMBOL_GPL(mbox_chan_received_data);
	155
	156	/**
	157	* mbox_chan_txdone - A way for controller driver to notify the
	158	* framework that the last TX has completed.
	159	* @chan: Pointer to the mailbox chan on which TX happened.
	160	* @r: Status of last TX - OK or ERROR
	161	*
	162	* The controller that has IRQ for TX ACK calls this atomic API
	163	* to tick the TX state machine. It works only if txdone_irq
	164	* is set by the controller.
	165	*/
	166	void mbox_chan_txdone(struct mbox_chan *chan, int r)
	167	{
	168	if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
	169	dev_err(chan->mbox->dev,
	170	"Controller can't run the TX ticker\n");
	171	return;
	172	}
	173
	174	tx_tick(chan, r);
	175	}
	176	EXPORT_SYMBOL_GPL(mbox_chan_txdone);
	177
	178	/**
	179	* mbox_client_txdone - The way for a client to run the TX state machine.
	180	* @chan: Mailbox channel assigned to this client.
	181	* @r: Success status of last transmission.
	182	*
	183	* The client/protocol had received some 'ACK' packet and it notifies
	184	* the API that the last packet was sent successfully. This only works
	185	* if the controller can't sense TX-Done.
	186	*/
	187	void mbox_client_txdone(struct mbox_chan *chan, int r)
	188	{
	189	if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
	190	dev_err(chan->mbox->dev, "Client can't run the TX ticker\n");
	191	return;
	192	}
	193
194	tx_tick(chan, r);
195	}
196	EXPORT_SYMBOL_GPL(mbox_client_txdone);
197
198	/**
199	* mbox_client_peek_data - A way for client driver to pull data
200	* received from remote by the controller.
201	* @chan: Mailbox channel assigned to this client.
202	*
203	* A poke to controller driver for any received data.
204	* The data is actually passed onto client via the
205	* mbox_chan_received_data()
206	* The call can be made from atomic context, so the controller's
207	* implementation of peek_data() must not sleep.
208	*
209	* Return: True, if controller has, and is going to push after this,
210	* some data.
211	* False, if controller doesn't have any data to be read.
212	*/
213	bool mbox_client_peek_data(struct mbox_chan *chan)
214	{
215	if (chan->mbox->ops->peek_data)
216	return chan->mbox->ops->peek_data(chan);
217
218	return false;
219	}
220	EXPORT_SYMBOL_GPL(mbox_client_peek_data);
221
222	/**
223	* mbox_send_message - For client to submit a message to be
224	* sent to the remote.
225	* @chan: Mailbox channel assigned to this client.
226	* @mssg: Client specific message typecasted.
227	*
228	* For client to submit data to the controller destined for a remote
229	* processor. If the client had set 'tx_block', the call will return
230	* either when the remote receives the data or when 'tx_tout' millisecs
231	* run out.
232	* In non-blocking mode, the requests are buffered by the API and a
233	* non-negative token is returned for each queued request. If the request
234	* is not queued, a negative token is returned. Upon failure or successful
235	* TX, the API calls 'tx_done' from atomic context, from which the client
236	* could submit yet another request.
237	* The pointer to message should be preserved until it is sent
238	* over the chan, i.e, tx_done() is made.
239	* This function could be called from atomic context as it simply
240	* queues the data and returns a token against the request.
241	*
242	* Return: Non-negative integer for successful submission (non-blocking mode)
243	* or transmission over chan (blocking mode).
244	* Negative value denotes failure.
245	*/
246	int mbox_send_message(struct mbox_chan chan, void mssg)
247	{
248	int t;
249
250	if (!chan \|\| !chan->cl)
251	return -EINVAL;
252
253	t = add_to_rbuf(chan, mssg);
254	if (t < 0) {
255	dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
256	return t;
257	}
258
259	msg_submit(chan);
260
2b6d83e2 JB	261	if (chan->cl->tx_block && chan->active_req) {
	262	unsigned long wait;
	263	int ret;
	264
	265	if (!chan->cl->tx_tout) /* wait forever */
	266	wait = msecs_to_jiffies(3600000);
	267	else
	268	wait = msecs_to_jiffies(chan->cl->tx_tout);
	269
	270	ret = wait_for_completion_timeout(&chan->tx_complete, wait);
	271	if (ret == 0) {
	272	t = -EIO;
	273	tx_tick(chan, -EIO);
	274	}
	275	}
	276
	277	return t;
	278	}
	279	EXPORT_SYMBOL_GPL(mbox_send_message);
	280
	281	/**
	282	* mbox_request_channel - Request a mailbox channel.
	283	* @cl: Identity of the client requesting the channel.
	284	* @index: Index of mailbox specifier in 'mboxes' property.
	285	*
	286	* The Client specifies its requirements and capabilities while asking for
	287	* a mailbox channel. It can't be called from atomic context.
	288	* The channel is exclusively allocated and can't be used by another
	289	* client before the owner calls mbox_free_channel.
	290	* After assignment, any packet received on this channel will be
	291	* handed over to the client via the 'rx_callback'.
	292	* The framework holds reference to the client, so the mbox_client
	293	* structure shouldn't be modified until the mbox_free_channel returns.
	294	*
	295	* Return: Pointer to the channel assigned to the client if successful.
	296	* ERR_PTR for request failure.
	297	*/
	298	struct mbox_chan mbox_request_channel(struct mbox_client cl, int index)
	299	{
	300	struct device *dev = cl->dev;
	301	struct mbox_controller *mbox;
	302	struct of_phandle_args spec;
	303	struct mbox_chan *chan;
	304	unsigned long flags;
	305	int ret;
	306
	307	if (!dev \|\| !dev->of_node) {
	308	pr_debug("%s: No owner device node\n", __func__);
	309	return ERR_PTR(-ENODEV);
	310	}
	311
	312	mutex_lock(&con_mutex);
	313
	314	if (of_parse_phandle_with_args(dev->of_node, "mboxes",
	315	"#mbox-cells", index, &spec)) {
	316	dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
	317	mutex_unlock(&con_mutex);
	318	return ERR_PTR(-ENODEV);
	319	}
	320
	321	chan = NULL;
	322	list_for_each_entry(mbox, &mbox_cons, node)
	323	if (mbox->dev->of_node == spec.np) {
	324	chan = mbox->of_xlate(mbox, &spec);
325	break;
326	}
327
328	of_node_put(spec.np);
329
330	if (!chan \|\| chan->cl \|\| !try_module_get(mbox->dev->driver->owner)) {
331	dev_dbg(dev, "%s: mailbox not free\n", __func__);
332	mutex_unlock(&con_mutex);
333	return ERR_PTR(-EBUSY);
334	}
335
336	spin_lock_irqsave(&chan->lock, flags);
337	chan->msg_free = 0;
338	chan->msg_count = 0;
339	chan->active_req = NULL;
340	chan->cl = cl;
341	init_completion(&chan->tx_complete);
342
343	if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
344	chan->txdone_method \|= TXDONE_BY_ACK;
345
346	spin_unlock_irqrestore(&chan->lock, flags);
347
348	ret = chan->mbox->ops->startup(chan);
349	if (ret) {
350	dev_err(dev, "Unable to startup the chan (%d)\n", ret);
351	mbox_free_channel(chan);
352	chan = ERR_PTR(ret);
353	}
354
355	mutex_unlock(&con_mutex);
356	return chan;
357	}
358	EXPORT_SYMBOL_GPL(mbox_request_channel);
359
360	/**
361	* mbox_free_channel - The client relinquishes control of a mailbox
362	* channel by this call.
363	* @chan: The mailbox channel to be freed.
364	*/
365	void mbox_free_channel(struct mbox_chan *chan)
366	{
367	unsigned long flags;
368
369	if (!chan \|\| !chan->cl)
370	return;
371
372	chan->mbox->ops->shutdown(chan);
373
374	/* The queued TX requests are simply aborted, no callbacks are made */
375	spin_lock_irqsave(&chan->lock, flags);
376	chan->cl = NULL;
377	chan->active_req = NULL;
378	if (chan->txdone_method == (TXDONE_BY_POLL \| TXDONE_BY_ACK))
379	chan->txdone_method = TXDONE_BY_POLL;
380
381	module_put(chan->mbox->dev->driver->owner);
382	spin_unlock_irqrestore(&chan->lock, flags);
383	}
384	EXPORT_SYMBOL_GPL(mbox_free_channel);
385
386	static struct mbox_chan *
387	of_mbox_index_xlate(struct mbox_controller *mbox,
388	const struct of_phandle_args *sp)
389	{
390	int ind = sp->args[0];
391
392	if (ind >= mbox->num_chans)
393	return NULL;
394
395	return &mbox->chans[ind];
396	}
397
398	/**
399	* mbox_controller_register - Register the mailbox controller
400	* @mbox: Pointer to the mailbox controller.
401	*
402	* The controller driver registers its communication channels
403	*/
404	int mbox_controller_register(struct mbox_controller *mbox)
405	{
406	int i, txdone;
407
408	/* Sanity check */
409	if (!mbox \|\| !mbox->dev \|\| !mbox->ops \|\| !mbox->num_chans)
410	return -EINVAL;
411
412	if (mbox->txdone_irq)
413	txdone = TXDONE_BY_IRQ;
414	else if (mbox->txdone_poll)
415	txdone = TXDONE_BY_POLL;
416	else /* It has to be ACK then */
417	txdone = TXDONE_BY_ACK;
418
419	if (txdone == TXDONE_BY_POLL) {
420	mbox->poll.function = &poll_txdone;
421	mbox->poll.data = (unsigned long)mbox;
422	init_timer(&mbox->poll);
423	}
424
425	for (i = 0; i < mbox->num_chans; i++) {
426	struct mbox_chan *chan = &mbox->chans[i];
427
428	chan->cl = NULL;
429	chan->mbox = mbox;
430	chan->txdone_method = txdone;
431	spin_lock_init(&chan->lock);
432	}
433
434	if (!mbox->of_xlate)
435	mbox->of_xlate = of_mbox_index_xlate;
436
437	mutex_lock(&con_mutex);
438	list_add_tail(&mbox->node, &mbox_cons);
439	mutex_unlock(&con_mutex);
440
441	return 0;
442	}
443	EXPORT_SYMBOL_GPL(mbox_controller_register);
444
445	/**
446	* mbox_controller_unregister - Unregister the mailbox controller
447	* @mbox: Pointer to the mailbox controller.
448	*/
449	void mbox_controller_unregister(struct mbox_controller *mbox)
450	{
451	int i;
452
453	if (!mbox)
454	return;
455
456	mutex_lock(&con_mutex);
457
458	list_del(&mbox->node);
459
460	for (i = 0; i < mbox->num_chans; i++)
461	mbox_free_channel(&mbox->chans[i]);
462
463	if (mbox->txdone_poll)
464	del_timer_sync(&mbox->poll);
465
466	mutex_unlock(&con_mutex);
467	}
468	EXPORT_SYMBOL_GPL(mbox_controller_unregister);