mailbox: Introduce framework for mailbox
Introduce common framework for client/protocol drivers and controller drivers of Inter-Processor-Communication (IPC). Client driver developers should have a look at include/linux/mailbox_client.h to understand the part of the API exposed to client drivers. Similarly controller driver developers should have a look at include/linux/mailbox_controller.h Reviewed-by: Mark Brown <broonie@linaro.org> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>hifive-unleashed-5.1
Jassi Brar
parent
f2fc42b6ac
commit
2b6d83e2b8
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@ -5740,6 +5740,14 @@ S: Maintained
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F: drivers/net/macvlan.c
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F: include/linux/if_macvlan.h
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MAILBOX API
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M: Jassi Brar <jassisinghbrar@gmail.com>
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L: linux-kernel@vger.kernel.org
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S: Maintained
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F: drivers/mailbox/
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F: include/linux/mailbox_client.h
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F: include/linux/mailbox_controller.h
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MAN-PAGES: MANUAL PAGES FOR LINUX -- Sections 2, 3, 4, 5, and 7
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M: Michael Kerrisk <mtk.manpages@gmail.com>
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W: http://www.kernel.org/doc/man-pages
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@ -1,3 +1,7 @@
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# Generic MAILBOX API
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obj-$(CONFIG_MAILBOX) += mailbox.o
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obj-$(CONFIG_PL320_MBOX) += pl320-ipc.o
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obj-$(CONFIG_OMAP2PLUS_MBOX) += omap-mailbox.o
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@ -0,0 +1,465 @@
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/*
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* Mailbox: Common code for Mailbox controllers and users
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*
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* Copyright (C) 2013-2014 Linaro Ltd.
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* Author: Jassi Brar <jassisinghbrar@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/interrupt.h>
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#include <linux/spinlock.h>
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#include <linux/mutex.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/bitops.h>
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#include <linux/mailbox_client.h>
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#include <linux/mailbox_controller.h>
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#define TXDONE_BY_IRQ BIT(0) /* controller has remote RTR irq */
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#define TXDONE_BY_POLL BIT(1) /* controller can read status of last TX */
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#define TXDONE_BY_ACK BIT(2) /* S/W ACK recevied by Client ticks the TX */
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static LIST_HEAD(mbox_cons);
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static DEFINE_MUTEX(con_mutex);
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static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
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{
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int idx;
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unsigned long flags;
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spin_lock_irqsave(&chan->lock, flags);
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/* See if there is any space left */
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if (chan->msg_count == MBOX_TX_QUEUE_LEN) {
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spin_unlock_irqrestore(&chan->lock, flags);
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return -ENOBUFS;
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}
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idx = chan->msg_free;
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chan->msg_data[idx] = mssg;
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chan->msg_count++;
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if (idx == MBOX_TX_QUEUE_LEN - 1)
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chan->msg_free = 0;
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else
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chan->msg_free++;
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spin_unlock_irqrestore(&chan->lock, flags);
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return idx;
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}
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static void msg_submit(struct mbox_chan *chan)
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{
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unsigned count, idx;
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unsigned long flags;
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void *data;
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int err;
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spin_lock_irqsave(&chan->lock, flags);
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if (!chan->msg_count || chan->active_req)
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goto exit;
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count = chan->msg_count;
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idx = chan->msg_free;
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if (idx >= count)
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idx -= count;
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else
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idx += MBOX_TX_QUEUE_LEN - count;
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data = chan->msg_data[idx];
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/* Try to submit a message to the MBOX controller */
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err = chan->mbox->ops->send_data(chan, data);
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if (!err) {
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chan->active_req = data;
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chan->msg_count--;
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}
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exit:
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spin_unlock_irqrestore(&chan->lock, flags);
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}
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static void tx_tick(struct mbox_chan *chan, int r)
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{
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unsigned long flags;
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void *mssg;
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spin_lock_irqsave(&chan->lock, flags);
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mssg = chan->active_req;
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chan->active_req = NULL;
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spin_unlock_irqrestore(&chan->lock, flags);
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/* Submit next message */
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msg_submit(chan);
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/* Notify the client */
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if (mssg && chan->cl->tx_done)
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chan->cl->tx_done(chan->cl, mssg, r);
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if (chan->cl->tx_block)
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complete(&chan->tx_complete);
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}
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static void poll_txdone(unsigned long data)
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{
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struct mbox_controller *mbox = (struct mbox_controller *)data;
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bool txdone, resched = false;
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int i;
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for (i = 0; i < mbox->num_chans; i++) {
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struct mbox_chan *chan = &mbox->chans[i];
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if (chan->active_req && chan->cl) {
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resched = true;
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txdone = chan->mbox->ops->last_tx_done(chan);
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if (txdone)
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tx_tick(chan, 0);
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}
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}
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if (resched)
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mod_timer(&mbox->poll, jiffies +
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msecs_to_jiffies(mbox->txpoll_period));
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}
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/**
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* mbox_chan_received_data - A way for controller driver to push data
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* received from remote to the upper layer.
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* @chan: Pointer to the mailbox channel on which RX happened.
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* @mssg: Client specific message typecasted as void *
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*
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* After startup and before shutdown any data received on the chan
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* is passed on to the API via atomic mbox_chan_received_data().
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* The controller should ACK the RX only after this call returns.
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*/
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void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
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{
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/* No buffering the received data */
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if (chan->cl->rx_callback)
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chan->cl->rx_callback(chan->cl, mssg);
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}
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EXPORT_SYMBOL_GPL(mbox_chan_received_data);
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/**
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* mbox_chan_txdone - A way for controller driver to notify the
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* framework that the last TX has completed.
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* @chan: Pointer to the mailbox chan on which TX happened.
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* @r: Status of last TX - OK or ERROR
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*
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* The controller that has IRQ for TX ACK calls this atomic API
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* to tick the TX state machine. It works only if txdone_irq
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* is set by the controller.
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*/
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void mbox_chan_txdone(struct mbox_chan *chan, int r)
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{
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if (unlikely(!(chan->txdone_method & TXDONE_BY_IRQ))) {
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dev_err(chan->mbox->dev,
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"Controller can't run the TX ticker\n");
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return;
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}
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tx_tick(chan, r);
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}
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EXPORT_SYMBOL_GPL(mbox_chan_txdone);
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/**
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* mbox_client_txdone - The way for a client to run the TX state machine.
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* @chan: Mailbox channel assigned to this client.
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* @r: Success status of last transmission.
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*
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* The client/protocol had received some 'ACK' packet and it notifies
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* the API that the last packet was sent successfully. This only works
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* if the controller can't sense TX-Done.
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*/
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void mbox_client_txdone(struct mbox_chan *chan, int r)
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{
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if (unlikely(!(chan->txdone_method & TXDONE_BY_ACK))) {
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dev_err(chan->mbox->dev, "Client can't run the TX ticker\n");
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return;
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}
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tx_tick(chan, r);
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}
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EXPORT_SYMBOL_GPL(mbox_client_txdone);
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/**
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* mbox_client_peek_data - A way for client driver to pull data
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* received from remote by the controller.
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* @chan: Mailbox channel assigned to this client.
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*
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* A poke to controller driver for any received data.
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* The data is actually passed onto client via the
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* mbox_chan_received_data()
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* The call can be made from atomic context, so the controller's
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* implementation of peek_data() must not sleep.
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*
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* Return: True, if controller has, and is going to push after this,
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* some data.
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* False, if controller doesn't have any data to be read.
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*/
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bool mbox_client_peek_data(struct mbox_chan *chan)
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{
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if (chan->mbox->ops->peek_data)
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return chan->mbox->ops->peek_data(chan);
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return false;
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}
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EXPORT_SYMBOL_GPL(mbox_client_peek_data);
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/**
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* mbox_send_message - For client to submit a message to be
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* sent to the remote.
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* @chan: Mailbox channel assigned to this client.
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* @mssg: Client specific message typecasted.
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*
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* For client to submit data to the controller destined for a remote
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* processor. If the client had set 'tx_block', the call will return
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* either when the remote receives the data or when 'tx_tout' millisecs
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* run out.
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* In non-blocking mode, the requests are buffered by the API and a
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* non-negative token is returned for each queued request. If the request
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* is not queued, a negative token is returned. Upon failure or successful
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* TX, the API calls 'tx_done' from atomic context, from which the client
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* could submit yet another request.
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* The pointer to message should be preserved until it is sent
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* over the chan, i.e, tx_done() is made.
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* This function could be called from atomic context as it simply
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* queues the data and returns a token against the request.
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*
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* Return: Non-negative integer for successful submission (non-blocking mode)
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* or transmission over chan (blocking mode).
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* Negative value denotes failure.
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*/
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int mbox_send_message(struct mbox_chan *chan, void *mssg)
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{
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int t;
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if (!chan || !chan->cl)
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return -EINVAL;
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t = add_to_rbuf(chan, mssg);
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if (t < 0) {
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dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
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return t;
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}
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msg_submit(chan);
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if (chan->txdone_method == TXDONE_BY_POLL)
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poll_txdone((unsigned long)chan->mbox);
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if (chan->cl->tx_block && chan->active_req) {
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unsigned long wait;
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int ret;
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if (!chan->cl->tx_tout) /* wait forever */
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wait = msecs_to_jiffies(3600000);
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else
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wait = msecs_to_jiffies(chan->cl->tx_tout);
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ret = wait_for_completion_timeout(&chan->tx_complete, wait);
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if (ret == 0) {
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t = -EIO;
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tx_tick(chan, -EIO);
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}
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}
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return t;
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}
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EXPORT_SYMBOL_GPL(mbox_send_message);
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/**
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* mbox_request_channel - Request a mailbox channel.
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* @cl: Identity of the client requesting the channel.
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* @index: Index of mailbox specifier in 'mboxes' property.
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*
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* The Client specifies its requirements and capabilities while asking for
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* a mailbox channel. It can't be called from atomic context.
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* The channel is exclusively allocated and can't be used by another
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* client before the owner calls mbox_free_channel.
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* After assignment, any packet received on this channel will be
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* handed over to the client via the 'rx_callback'.
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* The framework holds reference to the client, so the mbox_client
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* structure shouldn't be modified until the mbox_free_channel returns.
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*
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* Return: Pointer to the channel assigned to the client if successful.
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* ERR_PTR for request failure.
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*/
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struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
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{
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struct device *dev = cl->dev;
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struct mbox_controller *mbox;
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struct of_phandle_args spec;
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struct mbox_chan *chan;
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unsigned long flags;
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int ret;
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if (!dev || !dev->of_node) {
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pr_debug("%s: No owner device node\n", __func__);
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return ERR_PTR(-ENODEV);
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}
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mutex_lock(&con_mutex);
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if (of_parse_phandle_with_args(dev->of_node, "mboxes",
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"#mbox-cells", index, &spec)) {
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dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
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mutex_unlock(&con_mutex);
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return ERR_PTR(-ENODEV);
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}
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chan = NULL;
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list_for_each_entry(mbox, &mbox_cons, node)
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if (mbox->dev->of_node == spec.np) {
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chan = mbox->of_xlate(mbox, &spec);
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break;
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}
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of_node_put(spec.np);
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if (!chan || chan->cl || !try_module_get(mbox->dev->driver->owner)) {
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dev_dbg(dev, "%s: mailbox not free\n", __func__);
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mutex_unlock(&con_mutex);
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return ERR_PTR(-EBUSY);
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}
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spin_lock_irqsave(&chan->lock, flags);
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chan->msg_free = 0;
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chan->msg_count = 0;
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chan->active_req = NULL;
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chan->cl = cl;
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init_completion(&chan->tx_complete);
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if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
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chan->txdone_method |= TXDONE_BY_ACK;
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spin_unlock_irqrestore(&chan->lock, flags);
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ret = chan->mbox->ops->startup(chan);
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if (ret) {
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dev_err(dev, "Unable to startup the chan (%d)\n", ret);
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mbox_free_channel(chan);
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chan = ERR_PTR(ret);
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}
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mutex_unlock(&con_mutex);
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return chan;
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}
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EXPORT_SYMBOL_GPL(mbox_request_channel);
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/**
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* mbox_free_channel - The client relinquishes control of a mailbox
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* channel by this call.
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* @chan: The mailbox channel to be freed.
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*/
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void mbox_free_channel(struct mbox_chan *chan)
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{
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unsigned long flags;
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if (!chan || !chan->cl)
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return;
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chan->mbox->ops->shutdown(chan);
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/* The queued TX requests are simply aborted, no callbacks are made */
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spin_lock_irqsave(&chan->lock, flags);
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chan->cl = NULL;
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chan->active_req = NULL;
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if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
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chan->txdone_method = TXDONE_BY_POLL;
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module_put(chan->mbox->dev->driver->owner);
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spin_unlock_irqrestore(&chan->lock, flags);
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}
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EXPORT_SYMBOL_GPL(mbox_free_channel);
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static struct mbox_chan *
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of_mbox_index_xlate(struct mbox_controller *mbox,
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const struct of_phandle_args *sp)
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{
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int ind = sp->args[0];
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if (ind >= mbox->num_chans)
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return NULL;
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return &mbox->chans[ind];
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}
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/**
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* mbox_controller_register - Register the mailbox controller
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* @mbox: Pointer to the mailbox controller.
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*
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* The controller driver registers its communication channels
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*/
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int mbox_controller_register(struct mbox_controller *mbox)
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{
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int i, txdone;
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/* Sanity check */
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if (!mbox || !mbox->dev || !mbox->ops || !mbox->num_chans)
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return -EINVAL;
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if (mbox->txdone_irq)
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txdone = TXDONE_BY_IRQ;
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else if (mbox->txdone_poll)
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txdone = TXDONE_BY_POLL;
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else /* It has to be ACK then */
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txdone = TXDONE_BY_ACK;
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if (txdone == TXDONE_BY_POLL) {
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mbox->poll.function = &poll_txdone;
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mbox->poll.data = (unsigned long)mbox;
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init_timer(&mbox->poll);
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}
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for (i = 0; i < mbox->num_chans; i++) {
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struct mbox_chan *chan = &mbox->chans[i];
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chan->cl = NULL;
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chan->mbox = mbox;
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chan->txdone_method = txdone;
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spin_lock_init(&chan->lock);
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}
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if (!mbox->of_xlate)
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mbox->of_xlate = of_mbox_index_xlate;
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mutex_lock(&con_mutex);
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list_add_tail(&mbox->node, &mbox_cons);
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mutex_unlock(&con_mutex);
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return 0;
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}
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EXPORT_SYMBOL_GPL(mbox_controller_register);
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/**
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* mbox_controller_unregister - Unregister the mailbox controller
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* @mbox: Pointer to the mailbox controller.
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*/
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void mbox_controller_unregister(struct mbox_controller *mbox)
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{
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int i;
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if (!mbox)
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return;
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mutex_lock(&con_mutex);
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list_del(&mbox->node);
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|
||||
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);
|
||||
|
|
@ -0,0 +1,46 @@
|
|||
/*
|
||||
* 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.
|
||||
*/
|
||||
|
||||
#ifndef __MAILBOX_CLIENT_H
|
||||
#define __MAILBOX_CLIENT_H
|
||||
|
||||
#include <linux/of.h>
|
||||
#include <linux/device.h>
|
||||
|
||||
struct mbox_chan;
|
||||
|
||||
/**
|
||||
* struct mbox_client - User of a mailbox
|
||||
* @dev: The client device
|
||||
* @tx_block: If the mbox_send_message should block until data is
|
||||
* transmitted.
|
||||
* @tx_tout: Max block period in ms before TX is assumed failure
|
||||
* @knows_txdone: If the client could run the TX state machine. Usually
|
||||
* if the client receives some ACK packet for transmission.
|
||||
* Unused if the controller already has TX_Done/RTR IRQ.
|
||||
* @rx_callback: Atomic callback to provide client the data received
|
||||
* @tx_done: Atomic callback to tell client of data transmission
|
||||
*/
|
||||
struct mbox_client {
|
||||
struct device *dev;
|
||||
bool tx_block;
|
||||
unsigned long tx_tout;
|
||||
bool knows_txdone;
|
||||
|
||||
void (*rx_callback)(struct mbox_client *cl, void *mssg);
|
||||
void (*tx_done)(struct mbox_client *cl, void *mssg, int r);
|
||||
};
|
||||
|
||||
struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index);
|
||||
int mbox_send_message(struct mbox_chan *chan, void *mssg);
|
||||
void mbox_client_txdone(struct mbox_chan *chan, int r); /* atomic */
|
||||
bool mbox_client_peek_data(struct mbox_chan *chan); /* atomic */
|
||||
void mbox_free_channel(struct mbox_chan *chan); /* may sleep */
|
||||
|
||||
#endif /* __MAILBOX_CLIENT_H */
|
||||
|
|
@ -0,0 +1,133 @@
|
|||
/*
|
||||
* 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.
|
||||
*/
|
||||
|
||||
#ifndef __MAILBOX_CONTROLLER_H
|
||||
#define __MAILBOX_CONTROLLER_H
|
||||
|
||||
#include <linux/of.h>
|
||||
#include <linux/types.h>
|
||||
#include <linux/timer.h>
|
||||
#include <linux/device.h>
|
||||
#include <linux/completion.h>
|
||||
|
||||
struct mbox_chan;
|
||||
|
||||
/**
|
||||
* struct mbox_chan_ops - methods to control mailbox channels
|
||||
* @send_data: The API asks the MBOX controller driver, in atomic
|
||||
* context try to transmit a message on the bus. Returns 0 if
|
||||
* data is accepted for transmission, -EBUSY while rejecting
|
||||
* if the remote hasn't yet read the last data sent. Actual
|
||||
* transmission of data is reported by the controller via
|
||||
* mbox_chan_txdone (if it has some TX ACK irq). It must not
|
||||
* sleep.
|
||||
* @startup: Called when a client requests the chan. The controller
|
||||
* could ask clients for additional parameters of communication
|
||||
* to be provided via client's chan_data. This call may
|
||||
* block. After this call the Controller must forward any
|
||||
* data received on the chan by calling mbox_chan_received_data.
|
||||
* The controller may do stuff that need to sleep.
|
||||
* @shutdown: Called when a client relinquishes control of a chan.
|
||||
* This call may block too. The controller must not forward
|
||||
* any received data anymore.
|
||||
* The controller may do stuff that need to sleep.
|
||||
* @last_tx_done: If the controller sets 'txdone_poll', the API calls
|
||||
* this to poll status of last TX. The controller must
|
||||
* give priority to IRQ method over polling and never
|
||||
* set both txdone_poll and txdone_irq. Only in polling
|
||||
* mode 'send_data' is expected to return -EBUSY.
|
||||
* The controller may do stuff that need to sleep/block.
|
||||
* Used only if txdone_poll:=true && txdone_irq:=false
|
||||
* @peek_data: Atomic check for any received data. Return true if controller
|
||||
* has some data to push to the client. False otherwise.
|
||||
*/
|
||||
struct mbox_chan_ops {
|
||||
int (*send_data)(struct mbox_chan *chan, void *data);
|
||||
int (*startup)(struct mbox_chan *chan);
|
||||
void (*shutdown)(struct mbox_chan *chan);
|
||||
bool (*last_tx_done)(struct mbox_chan *chan);
|
||||
bool (*peek_data)(struct mbox_chan *chan);
|
||||
};
|
||||
|
||||
/**
|
||||
* struct mbox_controller - Controller of a class of communication channels
|
||||
* @dev: Device backing this controller
|
||||
* @ops: Operators that work on each communication chan
|
||||
* @chans: Array of channels
|
||||
* @num_chans: Number of channels in the 'chans' array.
|
||||
* @txdone_irq: Indicates if the controller can report to API when
|
||||
* the last transmitted data was read by the remote.
|
||||
* Eg, if it has some TX ACK irq.
|
||||
* @txdone_poll: If the controller can read but not report the TX
|
||||
* done. Ex, some register shows the TX status but
|
||||
* no interrupt rises. Ignored if 'txdone_irq' is set.
|
||||
* @txpoll_period: If 'txdone_poll' is in effect, the API polls for
|
||||
* last TX's status after these many millisecs
|
||||
* @of_xlate: Controller driver specific mapping of channel via DT
|
||||
* @poll: API private. Used to poll for TXDONE on all channels.
|
||||
* @node: API private. To hook into list of controllers.
|
||||
*/
|
||||
struct mbox_controller {
|
||||
struct device *dev;
|
||||
struct mbox_chan_ops *ops;
|
||||
struct mbox_chan *chans;
|
||||
int num_chans;
|
||||
bool txdone_irq;
|
||||
bool txdone_poll;
|
||||
unsigned txpoll_period;
|
||||
struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox,
|
||||
const struct of_phandle_args *sp);
|
||||
/* Internal to API */
|
||||
struct timer_list poll;
|
||||
struct list_head node;
|
||||
};
|
||||
|
||||
/*
|
||||
* 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 transfer 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.
|
||||
* REVISIT: 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
|
||||
|
||||
/**
|
||||
* struct mbox_chan - s/w representation of a communication chan
|
||||
* @mbox: Pointer to the parent/provider of this channel
|
||||
* @txdone_method: Way to detect TXDone chosen by the API
|
||||
* @cl: Pointer to the current owner of this channel
|
||||
* @tx_complete: Transmission completion
|
||||
* @active_req: Currently active request hook
|
||||
* @msg_count: No. of mssg currently queued
|
||||
* @msg_free: Index of next available mssg slot
|
||||
* @msg_data: Hook for data packet
|
||||
* @lock: Serialise access to the channel
|
||||
* @con_priv: Hook for controller driver to attach private data
|
||||
*/
|
||||
struct mbox_chan {
|
||||
struct mbox_controller *mbox;
|
||||
unsigned txdone_method;
|
||||
struct mbox_client *cl;
|
||||
struct completion tx_complete;
|
||||
void *active_req;
|
||||
unsigned msg_count, msg_free;
|
||||
void *msg_data[MBOX_TX_QUEUE_LEN];
|
||||
spinlock_t lock; /* Serialise access to the channel */
|
||||
void *con_priv;
|
||||
};
|
||||
|
||||
int mbox_controller_register(struct mbox_controller *mbox); /* can sleep */
|
||||
void mbox_controller_unregister(struct mbox_controller *mbox); /* can sleep */
|
||||
void mbox_chan_received_data(struct mbox_chan *chan, void *data); /* atomic */
|
||||
void mbox_chan_txdone(struct mbox_chan *chan, int r); /* atomic */
|
||||
|
||||
#endif /* __MAILBOX_CONTROLLER_H */
|
||||
Loading…
Reference in New Issue