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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/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;
}

00150 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");

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