[mirror_ubuntu-zesty-kernel.git] / drivers / mailbox / omap-mailbox.c

/*
 * OMAP mailbox driver
 *
 * Copyright (C) 2006-2009 Nokia Corporation. All rights reserved.
 * Copyright (C) 2013-2014 Texas Instruments Inc.
 *
 * Contact: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
 *          Suman Anna <s-anna@ti.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.
 *
 * 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/slab.h>
#include <linux/kfifo.h>
#include <linux/err.h>
#include <linux/notifier.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/platform_data/mailbox-omap.h>
#include <linux/omap-mailbox.h>

#define MAILBOX_REVISION                0x000
#define MAILBOX_MESSAGE(m)              (0x040 + 4 * (m))
#define MAILBOX_FIFOSTATUS(m)           (0x080 + 4 * (m))
#define MAILBOX_MSGSTATUS(m)            (0x0c0 + 4 * (m))

#define OMAP2_MAILBOX_IRQSTATUS(u)      (0x100 + 8 * (u))
#define OMAP2_MAILBOX_IRQENABLE(u)      (0x104 + 8 * (u))

#define OMAP4_MAILBOX_IRQSTATUS(u)      (0x104 + 0x10 * (u))
#define OMAP4_MAILBOX_IRQENABLE(u)      (0x108 + 0x10 * (u))
#define OMAP4_MAILBOX_IRQENABLE_CLR(u)  (0x10c + 0x10 * (u))

#define MAILBOX_IRQSTATUS(type, u)      (type ? OMAP4_MAILBOX_IRQSTATUS(u) : \
                                                OMAP2_MAILBOX_IRQSTATUS(u))
#define MAILBOX_IRQENABLE(type, u)      (type ? OMAP4_MAILBOX_IRQENABLE(u) : \
                                                OMAP2_MAILBOX_IRQENABLE(u))
#define MAILBOX_IRQDISABLE(type, u)     (type ? OMAP4_MAILBOX_IRQENABLE_CLR(u) \
                                                : OMAP2_MAILBOX_IRQENABLE(u))

#define MAILBOX_IRQ_NEWMSG(m)           (1 << (2 * (m)))
#define MAILBOX_IRQ_NOTFULL(m)          (1 << (2 * (m) + 1))

#define MBOX_REG_SIZE                   0x120

#define OMAP4_MBOX_REG_SIZE             0x130

#define MBOX_NR_REGS                    (MBOX_REG_SIZE / sizeof(u32))
#define OMAP4_MBOX_NR_REGS              (OMAP4_MBOX_REG_SIZE / sizeof(u32))

struct omap_mbox_fifo {
        unsigned long msg;
        unsigned long fifo_stat;
        unsigned long msg_stat;
        unsigned long irqenable;
        unsigned long irqstatus;
        unsigned long irqdisable;
        u32 intr_bit;
};

struct omap_mbox_queue {
        spinlock_t              lock;
        struct kfifo            fifo;
        struct work_struct      work;
        struct tasklet_struct   tasklet;
        struct omap_mbox        *mbox;
        bool full;
};

struct omap_mbox_device {
        struct device *dev;
        struct mutex cfg_lock;
        void __iomem *mbox_base;
        u32 num_users;
        u32 num_fifos;
        struct omap_mbox **mboxes;
        struct list_head elem;
};

struct omap_mbox {
        const char              *name;
        int                     irq;
        struct omap_mbox_queue  *txq, *rxq;
        struct device           *dev;
        struct omap_mbox_device *parent;
        struct omap_mbox_fifo   tx_fifo;
        struct omap_mbox_fifo   rx_fifo;
        u32                     ctx[OMAP4_MBOX_NR_REGS];
        u32                     intr_type;
        int                     use_count;
        struct blocking_notifier_head   notifier;
};

/* global variables for the mailbox devices */
static DEFINE_MUTEX(omap_mbox_devices_lock);
static LIST_HEAD(omap_mbox_devices);

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)");

static inline
unsigned int mbox_read_reg(struct omap_mbox_device *mdev, size_t ofs)
{
        return __raw_readl(mdev->mbox_base + ofs);
}

static inline
void mbox_write_reg(struct omap_mbox_device *mdev, u32 val, size_t ofs)
{
        __raw_writel(val, mdev->mbox_base + ofs);
}

/* Mailbox FIFO handle functions */
static mbox_msg_t mbox_fifo_read(struct omap_mbox *mbox)
{
        struct omap_mbox_fifo *fifo = &mbox->rx_fifo;
        return (mbox_msg_t) mbox_read_reg(mbox->parent, fifo->msg);
}

static void mbox_fifo_write(struct omap_mbox *mbox, mbox_msg_t msg)
{
        struct omap_mbox_fifo *fifo = &mbox->tx_fifo;
        mbox_write_reg(mbox->parent, msg, fifo->msg);
}

static int mbox_fifo_empty(struct omap_mbox *mbox)
{
        struct omap_mbox_fifo *fifo = &mbox->rx_fifo;
        return (mbox_read_reg(mbox->parent, fifo->msg_stat) == 0);
}

static int mbox_fifo_full(struct omap_mbox *mbox)
{
        struct omap_mbox_fifo *fifo = &mbox->tx_fifo;
        return mbox_read_reg(mbox->parent, fifo->fifo_stat);
}

/* Mailbox IRQ handle functions */
static void ack_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
{
        struct omap_mbox_fifo *fifo = (irq == IRQ_TX) ?
                                &mbox->tx_fifo : &mbox->rx_fifo;
        u32 bit = fifo->intr_bit;
        u32 irqstatus = fifo->irqstatus;

        mbox_write_reg(mbox->parent, bit, irqstatus);

        /* Flush posted write for irq status to avoid spurious interrupts */
        mbox_read_reg(mbox->parent, irqstatus);
}

static int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
{
        struct omap_mbox_fifo *fifo = (irq == IRQ_TX) ?
                                &mbox->tx_fifo : &mbox->rx_fifo;
        u32 bit = fifo->intr_bit;
        u32 irqenable = fifo->irqenable;
        u32 irqstatus = fifo->irqstatus;

        u32 enable = mbox_read_reg(mbox->parent, irqenable);
        u32 status = mbox_read_reg(mbox->parent, irqstatus);

        return (int)(enable & status & bit);
}

/*
 * message sender
 */
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_fifo_full(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);

void omap_mbox_save_ctx(struct omap_mbox *mbox)
{
        int i;
        int nr_regs;

        if (mbox->intr_type)
                nr_regs = OMAP4_MBOX_NR_REGS;
        else
                nr_regs = MBOX_NR_REGS;
        for (i = 0; i < nr_regs; i++) {
                mbox->ctx[i] = mbox_read_reg(mbox->parent, i * sizeof(u32));

                dev_dbg(mbox->dev, "%s: [%02x] %08x\n", __func__,
                        i, mbox->ctx[i]);
        }
}
EXPORT_SYMBOL(omap_mbox_save_ctx);

void omap_mbox_restore_ctx(struct omap_mbox *mbox)
{
        int i;
        int nr_regs;

        if (mbox->intr_type)
                nr_regs = OMAP4_MBOX_NR_REGS;
        else
                nr_regs = MBOX_NR_REGS;
        for (i = 0; i < nr_regs; i++) {
                mbox_write_reg(mbox->parent, mbox->ctx[i], i * sizeof(u32));

                dev_dbg(mbox->dev, "%s: [%02x] %08x\n", __func__,
                        i, mbox->ctx[i]);
        }
}
EXPORT_SYMBOL(omap_mbox_restore_ctx);

void omap_mbox_enable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
{
        u32 l;
        struct omap_mbox_fifo *fifo = (irq == IRQ_TX) ?
                                &mbox->tx_fifo : &mbox->rx_fifo;
        u32 bit = fifo->intr_bit;
        u32 irqenable = fifo->irqenable;

        l = mbox_read_reg(mbox->parent, irqenable);
        l |= bit;
        mbox_write_reg(mbox->parent, l, irqenable);
}
EXPORT_SYMBOL(omap_mbox_enable_irq);

void omap_mbox_disable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
{
        struct omap_mbox_fifo *fifo = (irq == IRQ_TX) ?
                                &mbox->tx_fifo : &mbox->rx_fifo;
        u32 bit = fifo->intr_bit;
        u32 irqdisable = fifo->irqdisable;

        /*
         * Read and update the interrupt configuration register for pre-OMAP4.
         * OMAP4 and later SoCs have a dedicated interrupt disabling register.
         */
        if (!mbox->intr_type)
                bit = mbox_read_reg(mbox->parent, irqdisable) & ~bit;

        mbox_write_reg(mbox->parent, bit, irqdisable);
}
EXPORT_SYMBOL(omap_mbox_disable_irq);

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_fifo_full(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));
        }

        /* 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;
        struct omap_mbox_device *mdev = mbox->parent;

        mutex_lock(&mdev->cfg_lock);
        ret = pm_runtime_get_sync(mdev->dev);
        if (unlikely(ret < 0))
                goto fail_startup;

        if (!mbox->use_count++) {
                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;
                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;
                }

                omap_mbox_enable_irq(mbox, IRQ_RX);
        }
        mutex_unlock(&mdev->cfg_lock);
        return 0;

fail_request_irq:
        mbox_queue_free(mbox->rxq);
fail_alloc_rxq:
        mbox_queue_free(mbox->txq);
fail_alloc_txq:
        pm_runtime_put_sync(mdev->dev);
        mbox->use_count--;
fail_startup:
        mutex_unlock(&mdev->cfg_lock);
        return ret;
}

static void omap_mbox_fini(struct omap_mbox *mbox)
{
        struct omap_mbox_device *mdev = mbox->parent;

        mutex_lock(&mdev->cfg_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);
        }

        pm_runtime_put_sync(mdev->dev);

        mutex_unlock(&mdev->cfg_lock);
}

static struct omap_mbox *omap_mbox_device_find(struct omap_mbox_device *mdev,
                                               const char *mbox_name)
{
        struct omap_mbox *_mbox, *mbox = NULL;
        struct omap_mbox **mboxes = mdev->mboxes;
        int i;

        if (!mboxes)
                return NULL;

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

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

        mutex_lock(&omap_mbox_devices_lock);
        list_for_each_entry(mdev, &omap_mbox_devices, elem) {
                mbox = omap_mbox_device_find(mdev, name);
                if (mbox)
                        break;
        }
        mutex_unlock(&omap_mbox_devices_lock);

        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", };

static int omap_mbox_register(struct omap_mbox_device *mdev)
{
        int ret;
        int i;
        struct omap_mbox **mboxes;

        if (!mdev || !mdev->mboxes)
                return -EINVAL;

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

                BLOCKING_INIT_NOTIFIER_HEAD(&mbox->notifier);
        }

        mutex_lock(&omap_mbox_devices_lock);
        list_add(&mdev->elem, &omap_mbox_devices);
        mutex_unlock(&omap_mbox_devices_lock);

        return 0;

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

static int omap_mbox_unregister(struct omap_mbox_device *mdev)
{
        int i;
        struct omap_mbox **mboxes;

        if (!mdev || !mdev->mboxes)
                return -EINVAL;

        mutex_lock(&omap_mbox_devices_lock);
        list_del(&mdev->elem);
        mutex_unlock(&omap_mbox_devices_lock);

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

static int omap_mbox_probe(struct platform_device *pdev)
{
        struct resource *mem;
        int ret;
        struct omap_mbox **list, *mbox, *mboxblk;
        struct omap_mbox_pdata *pdata = pdev->dev.platform_data;
        struct omap_mbox_dev_info *info;
        struct omap_mbox_device *mdev;
        struct omap_mbox_fifo *fifo;
        u32 intr_type;
        u32 l;
        int i;

        if (!pdata || !pdata->info_cnt || !pdata->info) {
                pr_err("%s: platform not supported\n", __func__);
                return -ENODEV;
        }

        mdev = devm_kzalloc(&pdev->dev, sizeof(*mdev), GFP_KERNEL);
        if (!mdev)
                return -ENOMEM;

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        mdev->mbox_base = devm_ioremap_resource(&pdev->dev, mem);
        if (IS_ERR(mdev->mbox_base))
                return PTR_ERR(mdev->mbox_base);

        /* allocate one extra for marking end of list */
        list = devm_kzalloc(&pdev->dev, (pdata->info_cnt + 1) * sizeof(*list),
                            GFP_KERNEL);
        if (!list)
                return -ENOMEM;

        mboxblk = devm_kzalloc(&pdev->dev, pdata->info_cnt * sizeof(*mbox),
                               GFP_KERNEL);
        if (!mboxblk)
                return -ENOMEM;

        info = pdata->info;
        intr_type = pdata->intr_type;
        mbox = mboxblk;
        for (i = 0; i < pdata->info_cnt; i++, info++) {
                fifo = &mbox->tx_fifo;
                fifo->msg = MAILBOX_MESSAGE(info->tx_id);
                fifo->fifo_stat = MAILBOX_FIFOSTATUS(info->tx_id);
                fifo->intr_bit = MAILBOX_IRQ_NOTFULL(info->tx_id);
                fifo->irqenable = MAILBOX_IRQENABLE(intr_type, info->usr_id);
                fifo->irqstatus = MAILBOX_IRQSTATUS(intr_type, info->usr_id);
                fifo->irqdisable = MAILBOX_IRQDISABLE(intr_type, info->usr_id);

                fifo = &mbox->rx_fifo;
                fifo->msg =  MAILBOX_MESSAGE(info->rx_id);
                fifo->msg_stat =  MAILBOX_MSGSTATUS(info->rx_id);
                fifo->intr_bit = MAILBOX_IRQ_NEWMSG(info->rx_id);
                fifo->irqenable = MAILBOX_IRQENABLE(intr_type, info->usr_id);
                fifo->irqstatus = MAILBOX_IRQSTATUS(intr_type, info->usr_id);
                fifo->irqdisable = MAILBOX_IRQDISABLE(intr_type, info->usr_id);

                mbox->intr_type = intr_type;

                mbox->parent = mdev;
                mbox->name = info->name;
                mbox->irq = platform_get_irq(pdev, info->irq_id);
                if (mbox->irq < 0)
                        return mbox->irq;
                list[i] = mbox++;
        }

        mutex_init(&mdev->cfg_lock);
        mdev->dev = &pdev->dev;
        mdev->num_users = pdata->num_users;
        mdev->num_fifos = pdata->num_fifos;
        mdev->mboxes = list;
        ret = omap_mbox_register(mdev);
        if (ret)
                return ret;

        platform_set_drvdata(pdev, mdev);
        pm_runtime_enable(mdev->dev);

        ret = pm_runtime_get_sync(mdev->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(mdev->dev);
                goto unregister;
        }

        /*
         * just print the raw revision register, the format is not
         * uniform across all SoCs
         */
        l = mbox_read_reg(mdev, MAILBOX_REVISION);
        dev_info(mdev->dev, "omap mailbox rev 0x%x\n", l);

        ret = pm_runtime_put_sync(mdev->dev);
        if (ret < 0)
                goto unregister;

        return 0;

unregister:
        pm_runtime_disable(mdev->dev);
        omap_mbox_unregister(mdev);
        return ret;
}

static int omap_mbox_remove(struct platform_device *pdev)
{
        struct omap_mbox_device *mdev = platform_get_drvdata(pdev);

        pm_runtime_disable(mdev->dev);
        omap_mbox_unregister(mdev);

        return 0;
}

static struct platform_driver omap_mbox_driver = {
        .probe  = omap_mbox_probe,
        .remove = omap_mbox_remove,
        .driver = {
                .name = "omap-mailbox",
                .owner = THIS_MODULE,
        },
};

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 platform_driver_register(&omap_mbox_driver);
}
subsys_initcall(omap_mbox_init);

static void __exit omap_mbox_exit(void)
{
        platform_driver_unregister(&omap_mbox_driver);
        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");