sir_dev.c

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/*********************************************************************
 *
 *  sir_dev.c:  irda sir network device
 * 
 *  Copyright (c) 2002 Martin Diehl
 * 
 *  This program is free software; you can redistribute it and/or 
 *  modify it under the terms of the GNU General Public License as 
 *  published by the Free Software Foundation; either version 2 of 
 *  the License, or (at your option) any later version.
 *
 ********************************************************************/    

#include <linux/hardirq.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/delay.h>

#include <net/irda/irda.h>
#include <net/irda/wrapper.h>
#include <net/irda/irda_device.h>

#include "sir-dev.h"


static struct workqueue_struct *irda_sir_wq;

/* STATE MACHINE */

/* substate handler of the config-fsm to handle the cases where we want
 * to wait for transmit completion before changing the port configuration
 */

static int sirdev_tx_complete_fsm(struct sir_dev *dev)
{
    struct sir_fsm *fsm = &dev->fsm;
    unsigned next_state, delay;
    unsigned bytes_left;

    do {
        next_state = fsm->substate; /* default: stay in current substate */
        delay = 0;

        switch(fsm->substate) {

        case SIRDEV_STATE_WAIT_XMIT:
            if (dev->drv->chars_in_buffer)
                bytes_left = dev->drv->chars_in_buffer(dev);
            else
                bytes_left = 0;
            if (!bytes_left) {
                next_state = SIRDEV_STATE_WAIT_UNTIL_SENT;
                break;
            }

            if (dev->speed > 115200)
                delay = (bytes_left*8*10000) / (dev->speed/100);
            else if (dev->speed > 0)
                delay = (bytes_left*10*10000) / (dev->speed/100);
            else
                delay = 0;
            /* expected delay (usec) until remaining bytes are sent */
            if (delay < 100) {
                udelay(delay);
                delay = 0;
                break;
            }
            /* sleep some longer delay (msec) */
            delay = (delay+999) / 1000;
            break;

        case SIRDEV_STATE_WAIT_UNTIL_SENT:
            /* block until underlaying hardware buffer are empty */
            if (dev->drv->wait_until_sent)
                dev->drv->wait_until_sent(dev);
            next_state = SIRDEV_STATE_TX_DONE;
            break;

        case SIRDEV_STATE_TX_DONE:
            return 0;

        default:
            IRDA_ERROR("%s - undefined state\n", __func__);
            return -EINVAL;
        }
        fsm->substate = next_state;
    } while (delay == 0);
    return delay;
}

/*
 * Function sirdev_config_fsm
 *
 * State machine to handle the configuration of the device (and attached dongle, if any).
 * This handler is scheduled for execution in kIrDAd context, so we can sleep.
 * however, kIrDAd is shared by all sir_dev devices so we better don't sleep there too
 * long. Instead, for longer delays we start a timer to reschedule us later.
 * On entry, fsm->sem is always locked and the netdev xmit queue stopped.
 * Both must be unlocked/restarted on completion - but only on final exit.
 */

static void sirdev_config_fsm(struct work_struct *work)
{
    struct sir_dev *dev = container_of(work, struct sir_dev, fsm.work.work);
    struct sir_fsm *fsm = &dev->fsm;
    int next_state;
    int ret = -1;
    unsigned delay;

    IRDA_DEBUG(2, "%s(), <%ld>\n", __func__, jiffies);

    do {
        IRDA_DEBUG(3, "%s - state=0x%04x / substate=0x%04x\n",
            __func__, fsm->state, fsm->substate);

        next_state = fsm->state;
        delay = 0;

        switch(fsm->state) {

        case SIRDEV_STATE_DONGLE_OPEN:
            if (dev->dongle_drv != NULL) {
                ret = sirdev_put_dongle(dev);
                if (ret) {
                    fsm->result = -EINVAL;
                    next_state = SIRDEV_STATE_ERROR;
                    break;
                }
            }

            /* Initialize dongle */
            ret = sirdev_get_dongle(dev, fsm->param);
            if (ret) {
                fsm->result = ret;
                next_state = SIRDEV_STATE_ERROR;
                break;
            }

            /* Dongles are powered through the modem control lines which
             * were just set during open. Before resetting, let's wait for
             * the power to stabilize. This is what some dongle drivers did
             * in open before, while others didn't - should be safe anyway.
             */

            delay = 50;
            fsm->substate = SIRDEV_STATE_DONGLE_RESET;
            next_state = SIRDEV_STATE_DONGLE_RESET;

            fsm->param = 9600;

            break;

        case SIRDEV_STATE_DONGLE_CLOSE:
            /* shouldn't we just treat this as success=? */
            if (dev->dongle_drv == NULL) {
                fsm->result = -EINVAL;
                next_state = SIRDEV_STATE_ERROR;
                break;
            }

            ret = sirdev_put_dongle(dev);
            if (ret) {
                fsm->result = ret;
                next_state = SIRDEV_STATE_ERROR;
                break;
            }
            next_state = SIRDEV_STATE_DONE;
            break;

        case SIRDEV_STATE_SET_DTR_RTS:
            ret = sirdev_set_dtr_rts(dev,
                (fsm->param&0x02) ? TRUE : FALSE,
                (fsm->param&0x01) ? TRUE : FALSE);
            next_state = SIRDEV_STATE_DONE;
            break;

        case SIRDEV_STATE_SET_SPEED:
            fsm->substate = SIRDEV_STATE_WAIT_XMIT;
            next_state = SIRDEV_STATE_DONGLE_CHECK;
            break;

        case SIRDEV_STATE_DONGLE_CHECK:
            ret = sirdev_tx_complete_fsm(dev);
            if (ret < 0) {
                fsm->result = ret;
                next_state = SIRDEV_STATE_ERROR;
                break;
            }
            if ((delay=ret) != 0)
                break;

            if (dev->dongle_drv) {
                fsm->substate = SIRDEV_STATE_DONGLE_RESET;
                next_state = SIRDEV_STATE_DONGLE_RESET;
            }
            else {
                dev->speed = fsm->param;
                next_state = SIRDEV_STATE_PORT_SPEED;
            }
            break;

        case SIRDEV_STATE_DONGLE_RESET:
            if (dev->dongle_drv->reset) {
                ret = dev->dongle_drv->reset(dev);
                if (ret < 0) {
                    fsm->result = ret;
                    next_state = SIRDEV_STATE_ERROR;
                    break;
                }
            }
            else
                ret = 0;
            if ((delay=ret) == 0) {
                /* set serial port according to dongle default speed */
                if (dev->drv->set_speed)
                    dev->drv->set_speed(dev, dev->speed);
                fsm->substate = SIRDEV_STATE_DONGLE_SPEED;
                next_state = SIRDEV_STATE_DONGLE_SPEED;
            }
            break;

        case SIRDEV_STATE_DONGLE_SPEED:
            if (dev->dongle_drv->set_speed) {
                ret = dev->dongle_drv->set_speed(dev, fsm->param);
                if (ret < 0) {
                    fsm->result = ret;
                    next_state = SIRDEV_STATE_ERROR;
                    break;
                }
            }
            else
                ret = 0;
            if ((delay=ret) == 0)
                next_state = SIRDEV_STATE_PORT_SPEED;
            break;

        case SIRDEV_STATE_PORT_SPEED:
            /* Finally we are ready to change the serial port speed */
            if (dev->drv->set_speed)
                dev->drv->set_speed(dev, dev->speed);
            dev->new_speed = 0;
            next_state = SIRDEV_STATE_DONE;
            break;

        case SIRDEV_STATE_DONE:
            /* Signal network layer so it can send more frames */
            netif_wake_queue(dev->netdev);
            next_state = SIRDEV_STATE_COMPLETE;
            break;

        default:
            IRDA_ERROR("%s - undefined state\n", __func__);
            fsm->result = -EINVAL;
            /* fall thru */

        case SIRDEV_STATE_ERROR:
            IRDA_ERROR("%s - error: %d\n", __func__, fsm->result);

#if 0   /* don't enable this before we have netdev->tx_timeout to recover */
            netif_stop_queue(dev->netdev);
#else
            netif_wake_queue(dev->netdev);
#endif
            /* fall thru */

        case SIRDEV_STATE_COMPLETE:
            /* config change finished, so we are not busy any longer */
            sirdev_enable_rx(dev);
            up(&fsm->sem);
            return;
        }
        fsm->state = next_state;
    } while(!delay);

    queue_delayed_work(irda_sir_wq, &fsm->work, msecs_to_jiffies(delay));
}

/* schedule some device configuration task for execution by kIrDAd
 * on behalf of the above state machine.
 * can be called from process or interrupt/tasklet context.
 */

int sirdev_schedule_request(struct sir_dev *dev, int initial_state, unsigned param)
{
    struct sir_fsm *fsm = &dev->fsm;

    IRDA_DEBUG(2, "%s - state=0x%04x / param=%u\n", __func__,
            initial_state, param);

    if (down_trylock(&fsm->sem)) {
        if (in_interrupt()  ||  in_atomic()  ||  irqs_disabled()) {
            IRDA_DEBUG(1, "%s(), state machine busy!\n", __func__);
            return -EWOULDBLOCK;
        } else
            down(&fsm->sem);
    }

    if (fsm->state == SIRDEV_STATE_DEAD) {
        /* race with sirdev_close should never happen */
        IRDA_ERROR("%s(), instance staled!\n", __func__);
        up(&fsm->sem);
        return -ESTALE;     /* or better EPIPE? */
    }

    netif_stop_queue(dev->netdev);
    atomic_set(&dev->enable_rx, 0);

    fsm->state = initial_state;
    fsm->param = param;
    fsm->result = 0;

    INIT_DELAYED_WORK(&fsm->work, sirdev_config_fsm);
    queue_delayed_work(irda_sir_wq, &fsm->work, 0);
    return 0;
}


/***************************************************************************/

void sirdev_enable_rx(struct sir_dev *dev)
{
    if (unlikely(atomic_read(&dev->enable_rx)))
        return;

    /* flush rx-buffer - should also help in case of problems with echo cancelation */
    dev->rx_buff.data = dev->rx_buff.head;
    dev->rx_buff.len = 0;
    dev->rx_buff.in_frame = FALSE;
    dev->rx_buff.state = OUTSIDE_FRAME;
    atomic_set(&dev->enable_rx, 1);
}

static int sirdev_is_receiving(struct sir_dev *dev)
{
    if (!atomic_read(&dev->enable_rx))
        return 0;

    return dev->rx_buff.state != OUTSIDE_FRAME;
}

int sirdev_set_dongle(struct sir_dev *dev, IRDA_DONGLE type)
{
    int err;

    IRDA_DEBUG(3, "%s : requesting dongle %d.\n", __func__, type);

    err = sirdev_schedule_dongle_open(dev, type);
    if (unlikely(err))
        return err;
    down(&dev->fsm.sem);        /* block until config change completed */
    err = dev->fsm.result;
    up(&dev->fsm.sem);
    return err;
}
EXPORT_SYMBOL(sirdev_set_dongle);

/* used by dongle drivers for dongle programming */

int sirdev_raw_write(struct sir_dev *dev, const char *buf, int len)
{
    unsigned long flags;
    int ret;

    if (unlikely(len > dev->tx_buff.truesize))
        return -ENOSPC;

    spin_lock_irqsave(&dev->tx_lock, flags);    /* serialize with other tx operations */
    while (dev->tx_buff.len > 0) {          /* wait until tx idle */
        spin_unlock_irqrestore(&dev->tx_lock, flags);
        msleep(10);
        spin_lock_irqsave(&dev->tx_lock, flags);
    }

    dev->tx_buff.data = dev->tx_buff.head;
    memcpy(dev->tx_buff.data, buf, len);    
    dev->tx_buff.len = len;

    ret = dev->drv->do_write(dev, dev->tx_buff.data, dev->tx_buff.len);
    if (ret > 0) {
        IRDA_DEBUG(3, "%s(), raw-tx started\n", __func__);

        dev->tx_buff.data += ret;
        dev->tx_buff.len -= ret;
        dev->raw_tx = 1;
        ret = len;      /* all data is going to be sent */
    }
    spin_unlock_irqrestore(&dev->tx_lock, flags);
    return ret;
}
EXPORT_SYMBOL(sirdev_raw_write);

/* seems some dongle drivers may need this */

int sirdev_raw_read(struct sir_dev *dev, char *buf, int len)
{
    int count;

    if (atomic_read(&dev->enable_rx))
        return -EIO;        /* fail if we expect irda-frames */

    count = (len < dev->rx_buff.len) ? len : dev->rx_buff.len;

    if (count > 0) {
        memcpy(buf, dev->rx_buff.data, count);
        dev->rx_buff.data += count;
        dev->rx_buff.len -= count;
    }

    /* remaining stuff gets flushed when re-enabling normal rx */

    return count;
}
EXPORT_SYMBOL(sirdev_raw_read);

int sirdev_set_dtr_rts(struct sir_dev *dev, int dtr, int rts)
{
    int ret = -ENXIO;
    if (dev->drv->set_dtr_rts)
        ret =  dev->drv->set_dtr_rts(dev, dtr, rts);
    return ret;
}
EXPORT_SYMBOL(sirdev_set_dtr_rts);

/**********************************************************************/

/* called from client driver - likely with bh-context - to indicate
 * it made some progress with transmission. Hence we send the next
 * chunk, if any, or complete the skb otherwise
 */

void sirdev_write_complete(struct sir_dev *dev)
{
    unsigned long flags;
    struct sk_buff *skb;
    int actual = 0;
    int err;
    
    spin_lock_irqsave(&dev->tx_lock, flags);

    IRDA_DEBUG(3, "%s() - dev->tx_buff.len = %d\n",
           __func__, dev->tx_buff.len);

    if (likely(dev->tx_buff.len > 0))  {
        /* Write data left in transmit buffer */
        actual = dev->drv->do_write(dev, dev->tx_buff.data, dev->tx_buff.len);

        if (likely(actual>0)) {
            dev->tx_buff.data += actual;
            dev->tx_buff.len  -= actual;
        }
        else if (unlikely(actual<0)) {
            /* could be dropped later when we have tx_timeout to recover */
            IRDA_ERROR("%s: drv->do_write failed (%d)\n",
                   __func__, actual);
            if ((skb=dev->tx_skb) != NULL) {
                dev->tx_skb = NULL;
                dev_kfree_skb_any(skb);
                dev->netdev->stats.tx_errors++;
                dev->netdev->stats.tx_dropped++;
            }
            dev->tx_buff.len = 0;
        }
        if (dev->tx_buff.len > 0)
            goto done;  /* more data to send later */
    }

    if (unlikely(dev->raw_tx != 0)) {
        /* in raw mode we are just done now after the buffer was sent
         * completely. Since this was requested by some dongle driver
         * running under the control of the irda-thread we must take
         * care here not to re-enable the queue. The queue will be
         * restarted when the irda-thread has completed the request.
         */

        IRDA_DEBUG(3, "%s(), raw-tx done\n", __func__);
        dev->raw_tx = 0;
        goto done;  /* no post-frame handling in raw mode */
    }

    /* we have finished now sending this skb.
     * update statistics and free the skb.
     * finally we check and trigger a pending speed change, if any.
     * if not we switch to rx mode and wake the queue for further
     * packets.
     * note the scheduled speed request blocks until the lower
     * client driver and the corresponding hardware has really
     * finished sending all data (xmit fifo drained f.e.)
     * before the speed change gets finally done and the queue
     * re-activated.
     */

    IRDA_DEBUG(5, "%s(), finished with frame!\n", __func__);
        
    if ((skb=dev->tx_skb) != NULL) {
        dev->tx_skb = NULL;
        dev->netdev->stats.tx_packets++;
        dev->netdev->stats.tx_bytes += skb->len;
        dev_kfree_skb_any(skb);
    }

    if (unlikely(dev->new_speed > 0)) {
        IRDA_DEBUG(5, "%s(), Changing speed!\n", __func__);
        err = sirdev_schedule_speed(dev, dev->new_speed);
        if (unlikely(err)) {
            /* should never happen
             * forget the speed change and hope the stack recovers
             */
            IRDA_ERROR("%s - schedule speed change failed: %d\n",
                   __func__, err);
            netif_wake_queue(dev->netdev);
        }
        /* else: success
         *  speed change in progress now
         *  on completion dev->new_speed gets cleared,
         *  rx-reenabled and the queue restarted
         */
    }
    else {
        sirdev_enable_rx(dev);
        netif_wake_queue(dev->netdev);
    }

done:
    spin_unlock_irqrestore(&dev->tx_lock, flags);
}
EXPORT_SYMBOL(sirdev_write_complete);

/* called from client driver - likely with bh-context - to give us
 * some more received bytes. We put them into the rx-buffer,
 * normally unwrapping and building LAP-skb's (unless rx disabled)
 */

int sirdev_receive(struct sir_dev *dev, const unsigned char *cp, size_t count) 
{
    if (!dev || !dev->netdev) {
        IRDA_WARNING("%s(), not ready yet!\n", __func__);
        return -1;
    }

    if (!dev->irlap) {
        IRDA_WARNING("%s - too early: %p / %zd!\n",
                 __func__, cp, count);
        return -1;
    }

    if (cp==NULL) {
        /* error already at lower level receive
         * just update stats and set media busy
         */
        irda_device_set_media_busy(dev->netdev, TRUE);
        dev->netdev->stats.rx_dropped++;
        IRDA_DEBUG(0, "%s; rx-drop: %zd\n", __func__, count);
        return 0;
    }

    /* Read the characters into the buffer */
    if (likely(atomic_read(&dev->enable_rx))) {
        while (count--)
            /* Unwrap and destuff one byte */
            async_unwrap_char(dev->netdev, &dev->netdev->stats,
                      &dev->rx_buff, *cp++);
    } else {
        while (count--) {
            /* rx not enabled: save the raw bytes and never
             * trigger any netif_rx. The received bytes are flushed
             * later when we re-enable rx but might be read meanwhile
             * by the dongle driver.
             */
            dev->rx_buff.data[dev->rx_buff.len++] = *cp++;

            /* What should we do when the buffer is full? */
            if (unlikely(dev->rx_buff.len == dev->rx_buff.truesize))
                dev->rx_buff.len = 0;
        }
    }

    return 0;
}
EXPORT_SYMBOL(sirdev_receive);

/**********************************************************************/

/* callbacks from network layer */

static netdev_tx_t sirdev_hard_xmit(struct sk_buff *skb,
                      struct net_device *ndev)
{
    struct sir_dev *dev = netdev_priv(ndev);
    unsigned long flags;
    int actual = 0;
    int err;
    s32 speed;

    IRDA_ASSERT(dev != NULL, return NETDEV_TX_OK;);

    netif_stop_queue(ndev);

    IRDA_DEBUG(3, "%s(), skb->len = %d\n", __func__, skb->len);

    speed = irda_get_next_speed(skb);
    if ((speed != dev->speed) && (speed != -1)) {
        if (!skb->len) {
            err = sirdev_schedule_speed(dev, speed);
            if (unlikely(err == -EWOULDBLOCK)) {
                /* Failed to initiate the speed change, likely the fsm
                 * is still busy (pretty unlikely, but...)
                 * We refuse to accept the skb and return with the queue
                 * stopped so the network layer will retry after the
                 * fsm completes and wakes the queue.
                 */
                 return NETDEV_TX_BUSY;
            }
            else if (unlikely(err)) {
                /* other fatal error - forget the speed change and
                 * hope the stack will recover somehow
                 */
                 netif_start_queue(ndev);
            }
            /* else: success
             *  speed change in progress now
             *  on completion the queue gets restarted
             */

            dev_kfree_skb_any(skb);
            return NETDEV_TX_OK;
        } else
            dev->new_speed = speed;
    }

    /* Init tx buffer*/
    dev->tx_buff.data = dev->tx_buff.head;

    /* Check problems */
    if(spin_is_locked(&dev->tx_lock)) {
        IRDA_DEBUG(3, "%s(), write not completed\n", __func__);
    }

    /* serialize with write completion */
    spin_lock_irqsave(&dev->tx_lock, flags);

        /* Copy skb to tx_buff while wrapping, stuffing and making CRC */
    dev->tx_buff.len = async_wrap_skb(skb, dev->tx_buff.data, dev->tx_buff.truesize); 

    /* transmission will start now - disable receive.
     * if we are just in the middle of an incoming frame,
     * treat it as collision. probably it's a good idea to
     * reset the rx_buf OUTSIDE_FRAME in this case too?
     */
    atomic_set(&dev->enable_rx, 0);
    if (unlikely(sirdev_is_receiving(dev)))
        dev->netdev->stats.collisions++;

    actual = dev->drv->do_write(dev, dev->tx_buff.data, dev->tx_buff.len);

    if (likely(actual > 0)) {
        dev->tx_skb = skb;
        dev->tx_buff.data += actual;
        dev->tx_buff.len -= actual;
    }
    else if (unlikely(actual < 0)) {
        /* could be dropped later when we have tx_timeout to recover */
        IRDA_ERROR("%s: drv->do_write failed (%d)\n",
               __func__, actual);
        dev_kfree_skb_any(skb);
        dev->netdev->stats.tx_errors++;
        dev->netdev->stats.tx_dropped++;
        netif_wake_queue(ndev);
    }
    spin_unlock_irqrestore(&dev->tx_lock, flags);

    return NETDEV_TX_OK;
}

/* called from network layer with rtnl hold */

static int sirdev_ioctl(struct net_device *ndev, struct ifreq *rq, int cmd)
{
    struct if_irda_req *irq = (struct if_irda_req *) rq;
    struct sir_dev *dev = netdev_priv(ndev);
    int ret = 0;

    IRDA_ASSERT(dev != NULL, return -1;);

    IRDA_DEBUG(3, "%s(), %s, (cmd=0x%X)\n", __func__, ndev->name, cmd);
    
    switch (cmd) {
    case SIOCSBANDWIDTH: /* Set bandwidth */
        if (!capable(CAP_NET_ADMIN))
            ret = -EPERM;
        else
            ret = sirdev_schedule_speed(dev, irq->ifr_baudrate);
        /* cannot sleep here for completion
         * we are called from network layer with rtnl hold
         */
        break;

    case SIOCSDONGLE: /* Set dongle */
        if (!capable(CAP_NET_ADMIN))
            ret = -EPERM;
        else
            ret = sirdev_schedule_dongle_open(dev, irq->ifr_dongle);
        /* cannot sleep here for completion
         * we are called from network layer with rtnl hold
         */
        break;

    case SIOCSMEDIABUSY: /* Set media busy */
        if (!capable(CAP_NET_ADMIN))
            ret = -EPERM;
        else
            irda_device_set_media_busy(dev->netdev, TRUE);
        break;

    case SIOCGRECEIVING: /* Check if we are receiving right now */
        irq->ifr_receiving = sirdev_is_receiving(dev);
        break;

    case SIOCSDTRRTS:
        if (!capable(CAP_NET_ADMIN))
            ret = -EPERM;
        else
            ret = sirdev_schedule_dtr_rts(dev, irq->ifr_dtr, irq->ifr_rts);
        /* cannot sleep here for completion
         * we are called from network layer with rtnl hold
         */
        break;

    case SIOCSMODE:
#if 0
        if (!capable(CAP_NET_ADMIN))
            ret = -EPERM;
        else
            ret = sirdev_schedule_mode(dev, irq->ifr_mode);
        /* cannot sleep here for completion
         * we are called from network layer with rtnl hold
         */
        break;
#endif
    default:
        ret = -EOPNOTSUPP;
    }
    
    return ret;
}

/* ----------------------------------------------------------------------------- */

#define SIRBUF_ALLOCSIZE 4269   /* worst case size of a wrapped IrLAP frame */

static int sirdev_alloc_buffers(struct sir_dev *dev)
{
    dev->tx_buff.truesize = SIRBUF_ALLOCSIZE;
    dev->rx_buff.truesize = IRDA_SKB_MAX_MTU; 

    /* Bootstrap ZeroCopy Rx */
    dev->rx_buff.skb = __netdev_alloc_skb(dev->netdev, dev->rx_buff.truesize,
                          GFP_KERNEL);
    if (dev->rx_buff.skb == NULL)
        return -ENOMEM;
    skb_reserve(dev->rx_buff.skb, 1);
    dev->rx_buff.head = dev->rx_buff.skb->data;

    dev->tx_buff.head = kmalloc(dev->tx_buff.truesize, GFP_KERNEL);
    if (dev->tx_buff.head == NULL) {
        kfree_skb(dev->rx_buff.skb);
        dev->rx_buff.skb = NULL;
        dev->rx_buff.head = NULL;
        return -ENOMEM;
    }

    dev->tx_buff.data = dev->tx_buff.head;
    dev->rx_buff.data = dev->rx_buff.head;
    dev->tx_buff.len = 0;
    dev->rx_buff.len = 0;

    dev->rx_buff.in_frame = FALSE;
    dev->rx_buff.state = OUTSIDE_FRAME;
    return 0;
};

static void sirdev_free_buffers(struct sir_dev *dev)
{
    kfree_skb(dev->rx_buff.skb);
    kfree(dev->tx_buff.head);
    dev->rx_buff.head = dev->tx_buff.head = NULL;
    dev->rx_buff.skb = NULL;
}

static int sirdev_open(struct net_device *ndev)
{
    struct sir_dev *dev = netdev_priv(ndev);
    const struct sir_driver *drv = dev->drv;

    if (!drv)
        return -ENODEV;

    /* increase the reference count of the driver module before doing serious stuff */
    if (!try_module_get(drv->owner))
        return -ESTALE;

    IRDA_DEBUG(2, "%s()\n", __func__);

    if (sirdev_alloc_buffers(dev))
        goto errout_dec;

    if (!dev->drv->start_dev  ||  dev->drv->start_dev(dev))
        goto errout_free;

    sirdev_enable_rx(dev);
    dev->raw_tx = 0;

    netif_start_queue(ndev);
    dev->irlap = irlap_open(ndev, &dev->qos, dev->hwname);
    if (!dev->irlap)
        goto errout_stop;

    netif_wake_queue(ndev);

    IRDA_DEBUG(2, "%s - done, speed = %d\n", __func__, dev->speed);

    return 0;

errout_stop:
    atomic_set(&dev->enable_rx, 0);
    if (dev->drv->stop_dev)
        dev->drv->stop_dev(dev);
errout_free:
    sirdev_free_buffers(dev);
errout_dec:
    module_put(drv->owner);
    return -EAGAIN;
}

static int sirdev_close(struct net_device *ndev)
{
    struct sir_dev *dev = netdev_priv(ndev);
    const struct sir_driver *drv;

//  IRDA_DEBUG(0, "%s\n", __func__);

    netif_stop_queue(ndev);

    down(&dev->fsm.sem);        /* block on pending config completion */

    atomic_set(&dev->enable_rx, 0);

    if (unlikely(!dev->irlap))
        goto out;
    irlap_close(dev->irlap);
    dev->irlap = NULL;

    drv = dev->drv;
    if (unlikely(!drv  ||  !dev->priv))
        goto out;

    if (drv->stop_dev)
        drv->stop_dev(dev);

    sirdev_free_buffers(dev);
    module_put(drv->owner);

out:
    dev->speed = 0;
    up(&dev->fsm.sem);
    return 0;
}

static const struct net_device_ops sirdev_ops = {
    .ndo_start_xmit = sirdev_hard_xmit,
    .ndo_open   = sirdev_open,
    .ndo_stop   = sirdev_close,
    .ndo_do_ioctl   = sirdev_ioctl,
};
/* ----------------------------------------------------------------------------- */

struct sir_dev * sirdev_get_instance(const struct sir_driver *drv, const char *name)
{
    struct net_device *ndev;
    struct sir_dev *dev;

    IRDA_DEBUG(0, "%s - %s\n", __func__, name);

    /* instead of adding tests to protect against drv->do_write==NULL
     * at several places we refuse to create a sir_dev instance for
     * drivers which don't implement do_write.
     */
    if (!drv ||  !drv->do_write)
        return NULL;

    /*
     *  Allocate new instance of the device
     */
    ndev = alloc_irdadev(sizeof(*dev));
    if (ndev == NULL) {
        IRDA_ERROR("%s - Can't allocate memory for IrDA control block!\n", __func__);
        goto out;
    }
    dev = netdev_priv(ndev);

    irda_init_max_qos_capabilies(&dev->qos);
    dev->qos.baud_rate.bits = IR_9600|IR_19200|IR_38400|IR_57600|IR_115200;
    dev->qos.min_turn_time.bits = drv->qos_mtt_bits;
    irda_qos_bits_to_value(&dev->qos);

    strncpy(dev->hwname, name, sizeof(dev->hwname)-1);

    atomic_set(&dev->enable_rx, 0);
    dev->tx_skb = NULL;

    spin_lock_init(&dev->tx_lock);
    sema_init(&dev->fsm.sem, 1);

    dev->drv = drv;
    dev->netdev = ndev;

    /* Override the network functions we need to use */
    ndev->netdev_ops = &sirdev_ops;

    if (register_netdev(ndev)) {
        IRDA_ERROR("%s(), register_netdev() failed!\n", __func__);
        goto out_freenetdev;
    }

    return dev;

out_freenetdev:
    free_netdev(ndev);
out:
    return NULL;
}
EXPORT_SYMBOL(sirdev_get_instance);

int sirdev_put_instance(struct sir_dev *dev)
{
    int err = 0;

    IRDA_DEBUG(0, "%s\n", __func__);

    atomic_set(&dev->enable_rx, 0);

    netif_carrier_off(dev->netdev);
    netif_device_detach(dev->netdev);

    if (dev->dongle_drv)
        err = sirdev_schedule_dongle_close(dev);
    if (err)
        IRDA_ERROR("%s - error %d\n", __func__, err);

    sirdev_close(dev->netdev);

    down(&dev->fsm.sem);
    dev->fsm.state = SIRDEV_STATE_DEAD; /* mark staled */
    dev->dongle_drv = NULL;
    dev->priv = NULL;
    up(&dev->fsm.sem);

    /* Remove netdevice */
    unregister_netdev(dev->netdev);

    free_netdev(dev->netdev);

    return 0;
}
EXPORT_SYMBOL(sirdev_put_instance);

static int __init sir_wq_init(void)
{
    irda_sir_wq = create_singlethread_workqueue("irda_sir_wq");
    if (!irda_sir_wq)
        return -ENOMEM;
    return 0;
}

static void __exit sir_wq_exit(void)
{
    destroy_workqueue(irda_sir_wq);
}

module_init(sir_wq_init);
module_exit(sir_wq_exit);

MODULE_AUTHOR("Martin Diehl <[email protected]>");
MODULE_DESCRIPTION("IrDA SIR core");
MODULE_LICENSE("GPL");