/*
 * OMAP mailbox driver
 *
 * Copyright (C) 2006-2009 Nokia Corporation. All rights reserved.
 *
 * Contact: Hiroshi DOYU <Hiroshi.DOYU@nokia.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/module.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/delay.h>

#include <mach/mailbox.h>

static int enable_seq_bit;
module_param(enable_seq_bit, bool, 0);
MODULE_PARM_DESC(enable_seq_bit, "Enable sequence bit checking.");

static struct omap_mbox *mboxes;
static DEFINE_RWLOCK(mboxes_lock);

/*
 * Mailbox sequence bit API
 */

/* seq_rcv should be initialized with any value other than
 * 0 and 1 << 31, to allow either value for the first
 * message.  */
static inline void mbox_seq_init(struct omap_mbox *mbox)
{
        if (!enable_seq_bit)
                return;

        /* any value other than 0 and 1 << 31 */
        mbox->seq_rcv = 0xffffffff;
}

static inline void mbox_seq_toggle(struct omap_mbox *mbox, mbox_msg_t * msg)
{
        if (!enable_seq_bit)
                return;

        /* add seq_snd to msg */
        *msg = (*msg & 0x7fffffff) | mbox->seq_snd;
        /* flip seq_snd */
        mbox->seq_snd ^= 1 << 31;
}

static inline int mbox_seq_test(struct omap_mbox *mbox, mbox_msg_t msg)
{
        mbox_msg_t seq;

        if (!enable_seq_bit)
                return 0;

        seq = msg & (1 << 31);
        if (seq == mbox->seq_rcv)
                return -1;
        mbox->seq_rcv = seq;
        return 0;
}

/* 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 enable_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
{
        mbox->ops->enable_irq(mbox, irq);
}
static inline void disable_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
{
        mbox->ops->disable_irq(mbox, irq);
}
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);
}

/* Mailbox Sequence Bit function */
void omap_mbox_init_seq(struct omap_mbox *mbox)
{
        mbox_seq_init(mbox);
}
EXPORT_SYMBOL(omap_mbox_init_seq);

/*
 * message sender
 */
static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg, void *arg)
{
        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);
        }

        if (arg && mbox->txq->callback) {
                ret = mbox->txq->callback(arg);
                if (ret)
                        goto out;
        }

        mbox_seq_toggle(mbox, &msg);
        mbox_fifo_write(mbox, msg);
 out:
        return ret;
}

struct omap_msg_tx_data {
        mbox_msg_t      msg;
        void            *arg;
};

static void omap_msg_tx_end_io(struct request *rq, int error)
{
        kfree(rq->special);
        __blk_put_request(rq->q, rq);
}

int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg, void* arg)
{
        struct omap_msg_tx_data *tx_data;
        struct request *rq;
        struct request_queue *q = mbox->txq->queue;

        tx_data = kmalloc(sizeof(*tx_data), GFP_ATOMIC);
        if (unlikely(!tx_data))
                return -ENOMEM;

        rq = blk_get_request(q, WRITE, GFP_ATOMIC);
        if (unlikely(!rq)) {
                kfree(tx_data);
                return -ENOMEM;
        }

        tx_data->msg = msg;
        tx_data->arg = arg;
        rq->end_io = omap_msg_tx_end_io;
        blk_insert_request(q, rq, 0, tx_data);

        schedule_work(&mbox->txq->work);
        return 0;
}
EXPORT_SYMBOL(omap_mbox_msg_send);

static void mbox_tx_work(struct work_struct *work)
{
        int ret;
        struct request *rq;
        struct omap_mbox_queue *mq = container_of(work,
                                struct omap_mbox_queue, work);
        struct omap_mbox *mbox = mq->queue->queuedata;
        struct request_queue *q = mbox->txq->queue;

        while (1) {
                struct omap_msg_tx_data *tx_data;

                spin_lock(q->queue_lock);
                rq = blk_fetch_request(q);
                spin_unlock(q->queue_lock);

                if (!rq)
                        break;

                tx_data = rq->special;

                ret = __mbox_msg_send(mbox, tx_data->msg, tx_data->arg);
                if (ret) {
                        enable_mbox_irq(mbox, IRQ_TX);
                        spin_lock(q->queue_lock);
                        blk_requeue_request(q, rq);
                        spin_unlock(q->queue_lock);
                        return;
                }

                spin_lock(q->queue_lock);
                __blk_end_request_all(rq, 0);
                spin_unlock(q->queue_lock);
        }
}

/*
 * 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);
        struct omap_mbox *mbox = mq->queue->queuedata;
        struct request_queue *q = mbox->rxq->queue;
        struct request *rq;
        mbox_msg_t msg;
        unsigned long flags;

        if (mbox->rxq->callback == NULL) {
                sysfs_notify(&mbox->dev->kobj, NULL, "mbox");
                return;
        }

        while (1) {
                spin_lock_irqsave(q->queue_lock, flags);
                rq = blk_fetch_request(q);
                spin_unlock_irqrestore(q->queue_lock, flags);
                if (!rq)
                        break;

                msg = (mbox_msg_t)rq->special;
                blk_end_request_all(rq, 0);
                mbox->rxq->callback((void *)msg);
        }
}

/*
 * Mailbox interrupt handler
 */
static void mbox_txq_fn(struct request_queue * q)
{
}

static void mbox_rxq_fn(struct request_queue * q)
{
}

static void __mbox_tx_interrupt(struct omap_mbox *mbox)
{
        disable_mbox_irq(mbox, IRQ_TX);
        ack_mbox_irq(mbox, IRQ_TX);
        schedule_work(&mbox->txq->work);
}

static void __mbox_rx_interrupt(struct omap_mbox *mbox)
{
        struct request *rq;
        mbox_msg_t msg;
        struct request_queue *q = mbox->rxq->queue;

        disable_mbox_irq(mbox, IRQ_RX);

        while (!mbox_fifo_empty(mbox)) {
                rq = blk_get_request(q, WRITE, GFP_ATOMIC);
                if (unlikely(!rq))
                        goto nomem;

                msg = mbox_fifo_read(mbox);

                if (unlikely(mbox_seq_test(mbox, msg))) {
                        pr_info("mbox: Illegal seq bit!(%08x)\n", msg);
                        if (mbox->err_notify)
                                mbox->err_notify();
                }

                blk_insert_request(q, rq, 0, (void *)msg);
                if (mbox->ops->type == OMAP_MBOX_TYPE1)
                        break;
        }

        /* no more messages in the fifo. clear IRQ source. */
        ack_mbox_irq(mbox, IRQ_RX);
        enable_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;
}

/*
 * sysfs files
 */
static ssize_t
omap_mbox_write(struct device *dev, struct device_attribute *attr,
                const char * buf, size_t count)
{
        int ret;
        mbox_msg_t *p = (mbox_msg_t *)buf;
        struct omap_mbox *mbox = dev_get_drvdata(dev);

        for (; count >= sizeof(mbox_msg_t); count -= sizeof(mbox_msg_t)) {
                ret = omap_mbox_msg_send(mbox, be32_to_cpu(*p), NULL);
                if (ret)
                        return -EAGAIN;
                p++;
        }

        return (size_t)((char *)p - buf);
}

static ssize_t
omap_mbox_read(struct device *dev, struct device_attribute *attr, char *buf)
{
        unsigned long flags;
        struct request *rq;
        mbox_msg_t *p = (mbox_msg_t *) buf;
        struct omap_mbox *mbox = dev_get_drvdata(dev);
        struct request_queue *q = mbox->rxq->queue;

        while (1) {
                spin_lock_irqsave(q->queue_lock, flags);
                rq = blk_fetch_request(q);
                spin_unlock_irqrestore(q->queue_lock, flags);

                if (!rq)
                        break;

                *p = (mbox_msg_t)rq->special;

                blk_end_request_all(rq, 0);

                if (unlikely(mbox_seq_test(mbox, *p))) {
                        pr_info("mbox: Illegal seq bit!(%08x) ignored\n", *p);
                        continue;
                }
                p++;
        }

        pr_debug("%02x %02x %02x %02x\n", buf[0], buf[1], buf[2], buf[3]);

        return (size_t) ((char *)p - buf);
}

static DEVICE_ATTR(mbox, S_IRUGO | S_IWUSR, omap_mbox_read, omap_mbox_write);

static ssize_t mbox_show(struct class *class, char *buf)
{
        return sprintf(buf, "mbox");
}

static CLASS_ATTR(mbox, S_IRUGO, mbox_show, NULL);

static struct class omap_mbox_class = {
        .name = "omap-mailbox",
};

static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
                                        request_fn_proc * proc,
                                        void (*work) (struct work_struct *))
{
        struct request_queue *q;
        struct omap_mbox_queue *mq;

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

        spin_lock_init(&mq->lock);

        q = blk_init_queue(proc, &mq->lock);
        if (!q)
                goto error;
        q->queuedata = mbox;
        mq->queue = q;

        INIT_WORK(&mq->work, work);

        return mq;
error:
        kfree(mq);
        return NULL;
}

static void mbox_queue_free(struct omap_mbox_queue *q)
{
        blk_cleanup_queue(q->queue);
        kfree(q);
}

static int omap_mbox_init(struct omap_mbox *mbox)
{
        int ret;
        struct omap_mbox_queue *mq;

        if (likely(mbox->ops->startup)) {
                ret = mbox->ops->startup(mbox);
                if (unlikely(ret))
                        return ret;
        }

        ret = request_irq(mbox->irq, mbox_interrupt, IRQF_DISABLED,
                                mbox->name, mbox);
        if (unlikely(ret)) {
                printk(KERN_ERR
                        "failed to register mailbox interrupt:%d\n", ret);
                goto fail_request_irq;
        }

        mq = mbox_queue_alloc(mbox, mbox_txq_fn, mbox_tx_work);
        if (!mq) {
                ret = -ENOMEM;
                goto fail_alloc_txq;
        }
        mbox->txq = mq;

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

        return 0;

 fail_alloc_rxq:
        mbox_queue_free(mbox->txq);
 fail_alloc_txq:
        free_irq(mbox->irq, mbox);
 fail_request_irq:
        if (unlikely(mbox->ops->shutdown))
                mbox->ops->shutdown(mbox);

        return ret;
}

static void omap_mbox_fini(struct omap_mbox *mbox)
{
        mbox_queue_free(mbox->txq);
        mbox_queue_free(mbox->rxq);

        free_irq(mbox->irq, mbox);

        if (unlikely(mbox->ops->shutdown))
                mbox->ops->shutdown(mbox);
}

static struct omap_mbox **find_mboxes(const char *name)
{
        struct omap_mbox **p;

        for (p = &mboxes; *p; p = &(*p)->next) {
                if (strcmp((*p)->name, name) == 0)
                        break;
        }

        return p;
}

struct omap_mbox *omap_mbox_get(const char *name)
{
        struct omap_mbox *mbox;
        int ret;

        read_lock(&mboxes_lock);
        mbox = *(find_mboxes(name));
        if (mbox == NULL) {
                read_unlock(&mboxes_lock);
                return ERR_PTR(-ENOENT);
        }

        read_unlock(&mboxes_lock);

        ret = omap_mbox_init(mbox);
        if (ret)
                return ERR_PTR(-ENODEV);

        return mbox;
}
EXPORT_SYMBOL(omap_mbox_get);

void omap_mbox_put(struct omap_mbox *mbox)
{
        omap_mbox_fini(mbox);
}
EXPORT_SYMBOL(omap_mbox_put);

int omap_mbox_register(struct device *parent, struct omap_mbox *mbox)
{
        int ret = 0;
        struct omap_mbox **tmp;

        if (!mbox)
                return -EINVAL;
        if (mbox->next)
                return -EBUSY;

        mbox->dev = device_create(&omap_mbox_class,
                                  parent, 0, mbox, "%s", mbox->name);
        if (IS_ERR(mbox->dev))
                return PTR_ERR(mbox->dev);

        ret = device_create_file(mbox->dev, &dev_attr_mbox);
        if (ret)
                goto err_sysfs;

        write_lock(&mboxes_lock);
        tmp = find_mboxes(mbox->name);
        if (*tmp) {
                ret = -EBUSY;
                write_unlock(&mboxes_lock);
                goto err_find;
        }
        *tmp = mbox;
        write_unlock(&mboxes_lock);

        return 0;

err_find:
        device_remove_file(mbox->dev, &dev_attr_mbox);
err_sysfs:
        device_unregister(mbox->dev);
        return ret;
}
EXPORT_SYMBOL(omap_mbox_register);

int omap_mbox_unregister(struct omap_mbox *mbox)
{
        struct omap_mbox **tmp;

        write_lock(&mboxes_lock);
        tmp = &mboxes;
        while (*tmp) {
                if (mbox == *tmp) {
                        *tmp = mbox->next;
                        mbox->next = NULL;
                        write_unlock(&mboxes_lock);
                        device_remove_file(mbox->dev, &dev_attr_mbox);
                        device_unregister(mbox->dev);
                        return 0;
                }
                tmp = &(*tmp)->next;
        }
        write_unlock(&mboxes_lock);

        return -EINVAL;
}
EXPORT_SYMBOL(omap_mbox_unregister);

static int __init omap_mbox_class_init(void)
{
        int ret = class_register(&omap_mbox_class);
        if (!ret)
                ret = class_create_file(&omap_mbox_class, &class_attr_mbox);

        return ret;
}

static void __exit omap_mbox_class_exit(void)
{
        class_remove_file(&omap_mbox_class, &class_attr_mbox);
        class_unregister(&omap_mbox_class);
}

subsys_initcall(omap_mbox_class_init);
module_exit(omap_mbox_class_exit);

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