mailbox.c

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/*
 * OMAP mailbox driver
 *
 * Copyright (C) 2006-2009 Nokia Corporation. All rights reserved.
 *
 * Contact: Hiroshi DOYU <[email protected]>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/kfifo.h>
#include <linux/err.h>
#include <linux/notifier.h>
#include <linux/module.h>

#include <plat/mailbox.h>

static struct omap_mbox **mboxes;

static int mbox_configured;
static DEFINE_MUTEX(mbox_configured_lock);

static unsigned int mbox_kfifo_size = CONFIG_OMAP_MBOX_KFIFO_SIZE;
module_param(mbox_kfifo_size, uint, S_IRUGO);
MODULE_PARM_DESC(mbox_kfifo_size, "Size of omap's mailbox kfifo (bytes)");

/* Mailbox FIFO handle functions */
static inline mbox_msg_t mbox_fifo_read(struct omap_mbox *mbox)
{
    return mbox->ops->fifo_read(mbox);
}
static inline void mbox_fifo_write(struct omap_mbox *mbox, mbox_msg_t msg)
{
    mbox->ops->fifo_write(mbox, msg);
}
static inline int mbox_fifo_empty(struct omap_mbox *mbox)
{
    return mbox->ops->fifo_empty(mbox);
}
static inline int mbox_fifo_full(struct omap_mbox *mbox)
{
    return mbox->ops->fifo_full(mbox);
}

/* Mailbox IRQ handle functions */
static inline void ack_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
{
    if (mbox->ops->ack_irq)
        mbox->ops->ack_irq(mbox, irq);
}
static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
{
    return mbox->ops->is_irq(mbox, irq);
}

/*
 * message sender
 */
static int __mbox_poll_for_space(struct omap_mbox *mbox)
{
    int ret = 0, i = 1000;

    while (mbox_fifo_full(mbox)) {
        if (mbox->ops->type == OMAP_MBOX_TYPE2)
            return -1;
        if (--i == 0)
            return -1;
        udelay(1);
    }
    return ret;
}

int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
{
    struct omap_mbox_queue *mq = mbox->txq;
    int ret = 0, len;

    spin_lock_bh(&mq->lock);

    if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
        ret = -ENOMEM;
        goto out;
    }

    if (kfifo_is_empty(&mq->fifo) && !__mbox_poll_for_space(mbox)) {
        mbox_fifo_write(mbox, msg);
        goto out;
    }

    len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
    WARN_ON(len != sizeof(msg));

    tasklet_schedule(&mbox->txq->tasklet);

out:
    spin_unlock_bh(&mq->lock);
    return ret;
}
EXPORT_SYMBOL(omap_mbox_msg_send);

static void mbox_tx_tasklet(unsigned long tx_data)
{
    struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
    struct omap_mbox_queue *mq = mbox->txq;
    mbox_msg_t msg;
    int ret;

    while (kfifo_len(&mq->fifo)) {
        if (__mbox_poll_for_space(mbox)) {
            omap_mbox_enable_irq(mbox, IRQ_TX);
            break;
        }

        ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
                                sizeof(msg));
        WARN_ON(ret != sizeof(msg));

        mbox_fifo_write(mbox, msg);
    }
}

/*
 * Message receiver(workqueue)
 */
static void mbox_rx_work(struct work_struct *work)
{
    struct omap_mbox_queue *mq =
            container_of(work, struct omap_mbox_queue, work);
    mbox_msg_t msg;
    int len;

    while (kfifo_len(&mq->fifo) >= sizeof(msg)) {
        len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
        WARN_ON(len != sizeof(msg));

        blocking_notifier_call_chain(&mq->mbox->notifier, len,
                                (void *)msg);
        spin_lock_irq(&mq->lock);
        if (mq->full) {
            mq->full = false;
            omap_mbox_enable_irq(mq->mbox, IRQ_RX);
        }
        spin_unlock_irq(&mq->lock);
    }
}

/*
 * Mailbox interrupt handler
 */
static void __mbox_tx_interrupt(struct omap_mbox *mbox)
{
    omap_mbox_disable_irq(mbox, IRQ_TX);
    ack_mbox_irq(mbox, IRQ_TX);
    tasklet_schedule(&mbox->txq->tasklet);
}

static void __mbox_rx_interrupt(struct omap_mbox *mbox)
{
    struct omap_mbox_queue *mq = mbox->rxq;
    mbox_msg_t msg;
    int len;

    while (!mbox_fifo_empty(mbox)) {
        if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg))) {
            omap_mbox_disable_irq(mbox, IRQ_RX);
            mq->full = true;
            goto nomem;
        }

        msg = mbox_fifo_read(mbox);

        len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
        WARN_ON(len != sizeof(msg));

        if (mbox->ops->type == OMAP_MBOX_TYPE1)
            break;
    }

    /* no more messages in the fifo. clear IRQ source. */
    ack_mbox_irq(mbox, IRQ_RX);
nomem:
    schedule_work(&mbox->rxq->work);
}

static irqreturn_t mbox_interrupt(int irq, void *p)
{
    struct omap_mbox *mbox = p;

    if (is_mbox_irq(mbox, IRQ_TX))
        __mbox_tx_interrupt(mbox);

    if (is_mbox_irq(mbox, IRQ_RX))
        __mbox_rx_interrupt(mbox);

    return IRQ_HANDLED;
}

static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
                    void (*work) (struct work_struct *),
                    void (*tasklet)(unsigned long))
{
    struct omap_mbox_queue *mq;

    mq = kzalloc(sizeof(struct omap_mbox_queue), GFP_KERNEL);
    if (!mq)
        return NULL;

    spin_lock_init(&mq->lock);

    if (kfifo_alloc(&mq->fifo, mbox_kfifo_size, GFP_KERNEL))
        goto error;

    if (work)
        INIT_WORK(&mq->work, work);

    if (tasklet)
        tasklet_init(&mq->tasklet, tasklet, (unsigned long)mbox);
    return mq;
error:
    kfree(mq);
    return NULL;
}

static void mbox_queue_free(struct omap_mbox_queue *q)
{
    kfifo_free(&q->fifo);
    kfree(q);
}

static int omap_mbox_startup(struct omap_mbox *mbox)
{
    int ret = 0;
    struct omap_mbox_queue *mq;

    mutex_lock(&mbox_configured_lock);
    if (!mbox_configured++) {
        if (likely(mbox->ops->startup)) {
            ret = mbox->ops->startup(mbox);
            if (unlikely(ret))
                goto fail_startup;
        } else
            goto fail_startup;
    }

    if (!mbox->use_count++) {
        ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
                            mbox->name, mbox);
        if (unlikely(ret)) {
            pr_err("failed to register mailbox interrupt:%d\n",
                                    ret);
            goto fail_request_irq;
        }
        mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
        if (!mq) {
            ret = -ENOMEM;
            goto fail_alloc_txq;
        }
        mbox->txq = mq;

        mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
        if (!mq) {
            ret = -ENOMEM;
            goto fail_alloc_rxq;
        }
        mbox->rxq = mq;
        mq->mbox = mbox;

        omap_mbox_enable_irq(mbox, IRQ_RX);
    }
    mutex_unlock(&mbox_configured_lock);
    return 0;

fail_alloc_rxq:
    mbox_queue_free(mbox->txq);
fail_alloc_txq:
    free_irq(mbox->irq, mbox);
fail_request_irq:
    if (mbox->ops->shutdown)
        mbox->ops->shutdown(mbox);
    mbox->use_count--;
fail_startup:
    mbox_configured--;
    mutex_unlock(&mbox_configured_lock);
    return ret;
}

static void omap_mbox_fini(struct omap_mbox *mbox)
{
    mutex_lock(&mbox_configured_lock);

    if (!--mbox->use_count) {
        omap_mbox_disable_irq(mbox, IRQ_RX);
        free_irq(mbox->irq, mbox);
        tasklet_kill(&mbox->txq->tasklet);
        flush_work(&mbox->rxq->work);
        mbox_queue_free(mbox->txq);
        mbox_queue_free(mbox->rxq);
    }

    if (likely(mbox->ops->shutdown)) {
        if (!--mbox_configured)
            mbox->ops->shutdown(mbox);
    }

    mutex_unlock(&mbox_configured_lock);
}

struct omap_mbox *omap_mbox_get(const char *name, struct notifier_block *nb)
{
    struct omap_mbox *_mbox, *mbox = NULL;
    int i, ret;

    if (!mboxes)
        return ERR_PTR(-EINVAL);

    for (i = 0; (_mbox = mboxes[i]); i++) {
        if (!strcmp(_mbox->name, name)) {
            mbox = _mbox;
            break;
        }
    }

    if (!mbox)
        return ERR_PTR(-ENOENT);

    if (nb)
        blocking_notifier_chain_register(&mbox->notifier, nb);

    ret = omap_mbox_startup(mbox);
    if (ret) {
        blocking_notifier_chain_unregister(&mbox->notifier, nb);
        return ERR_PTR(-ENODEV);
    }

    return mbox;
}
EXPORT_SYMBOL(omap_mbox_get);

void omap_mbox_put(struct omap_mbox *mbox, struct notifier_block *nb)
{
    blocking_notifier_chain_unregister(&mbox->notifier, nb);
    omap_mbox_fini(mbox);
}
EXPORT_SYMBOL(omap_mbox_put);

static struct class omap_mbox_class = { .name = "mbox", };

int omap_mbox_register(struct device *parent, struct omap_mbox **list)
{
    int ret;
    int i;

    mboxes = list;
    if (!mboxes)
        return -EINVAL;

    for (i = 0; mboxes[i]; i++) {
        struct omap_mbox *mbox = mboxes[i];
        mbox->dev = device_create(&omap_mbox_class,
                parent, 0, mbox, "%s", mbox->name);
        if (IS_ERR(mbox->dev)) {
            ret = PTR_ERR(mbox->dev);
            goto err_out;
        }

        BLOCKING_INIT_NOTIFIER_HEAD(&mbox->notifier);
    }
    return 0;

err_out:
    while (i--)
        device_unregister(mboxes[i]->dev);
    return ret;
}
EXPORT_SYMBOL(omap_mbox_register);

int omap_mbox_unregister(void)
{
    int i;

    if (!mboxes)
        return -EINVAL;

    for (i = 0; mboxes[i]; i++)
        device_unregister(mboxes[i]->dev);
    mboxes = NULL;
    return 0;
}
EXPORT_SYMBOL(omap_mbox_unregister);

static int __init omap_mbox_init(void)
{
    int err;

    err = class_register(&omap_mbox_class);
    if (err)
        return err;

    /* kfifo size sanity check: alignment and minimal size */
    mbox_kfifo_size = ALIGN(mbox_kfifo_size, sizeof(mbox_msg_t));
    mbox_kfifo_size = max_t(unsigned int, mbox_kfifo_size,
                            sizeof(mbox_msg_t));

    return 0;
}
subsys_initcall(omap_mbox_init);

static void __exit omap_mbox_exit(void)
{
    class_unregister(&omap_mbox_class);
}
module_exit(omap_mbox_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("omap mailbox: interrupt driven messaging");
MODULE_AUTHOR("Toshihiro Kobayashi");
MODULE_AUTHOR("Hiroshi DOYU");