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mailbox.c

/*
 * 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/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 <plat/mailbox.h>

static struct workqueue_struct *mboxd;
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:
      queue_work(mboxd, &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;
      }
      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) {
            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;
      int ret;

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

      for (mbox = *mboxes; mbox; mbox++)
            if (!strcmp(mbox->name, name))
                  break;

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

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

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

      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;

      mboxd = create_workqueue("mboxd");
      if (!mboxd)
            return -ENOMEM;

      /* 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)
{
      destroy_workqueue(mboxd);
      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");

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