stir4200.c

Go to the documentation of this file.

/*****************************************************************************
*
* Filename:      stir4200.c
* Version:       0.4
* Description:   Irda SigmaTel USB Dongle
* Status:        Experimental
* Author:        Stephen Hemminger <[email protected]>
*
*   Based on earlier driver by Paul Stewart <[email protected]>
*
*   Copyright (C) 2000, Roman Weissgaerber <[email protected]>
*   Copyright (C) 2001, Dag Brattli <[email protected]>
*   Copyright (C) 2001, Jean Tourrilhes <[email protected]>
*   Copyright (C) 2004, Stephen Hemminger <[email protected]>
*
*   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.
*
*   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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*****************************************************************************/

/*
 * This dongle does no framing, and requires polling to receive the
 * data.  The STIr4200 has bulk in and out endpoints just like
 * usr-irda devices, but the data it sends and receives is raw; like
 * irtty, it needs to call the wrap and unwrap functions to add and
 * remove SOF/BOF and escape characters to/from the frame.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/usb.h>
#include <linux/crc32.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <net/irda/irda.h>
#include <net/irda/irda_device.h>
#include <net/irda/wrapper.h>
#include <net/irda/crc.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>

MODULE_AUTHOR("Stephen Hemminger <[email protected]>");
MODULE_DESCRIPTION("IrDA-USB Dongle Driver for SigmaTel STIr4200");
MODULE_LICENSE("GPL");

static int qos_mtt_bits = 0x07; /* 1 ms or more */
module_param(qos_mtt_bits, int, 0);
MODULE_PARM_DESC(qos_mtt_bits, "Minimum Turn Time");

static int rx_sensitivity = 1;  /* FIR 0..4, SIR 0..6 */
module_param(rx_sensitivity, int, 0);
MODULE_PARM_DESC(rx_sensitivity, "Set Receiver sensitivity (0-6, 0 is most sensitive)");

static int tx_power = 0;    /* 0 = highest ... 3 = lowest */
module_param(tx_power, int, 0);
MODULE_PARM_DESC(tx_power, "Set Transmitter power (0-3, 0 is highest power)");

#define STIR_IRDA_HEADER    4
#define CTRL_TIMEOUT        100    /* milliseconds */
#define TRANSMIT_TIMEOUT    200    /* milliseconds */
#define STIR_FIFO_SIZE      4096
#define FIFO_REGS_SIZE      3

enum FirChars {
    FIR_CE   = 0x7d,
    FIR_XBOF = 0x7f,
    FIR_EOF  = 0x7e,
};

enum StirRequests {
    REQ_WRITE_REG =     0x00,
    REQ_READ_REG =      0x01,
    REQ_READ_ROM =      0x02,
    REQ_WRITE_SINGLE =  0x03,
};

/* Register offsets */
enum StirRegs {
    REG_RSVD=0,
    REG_MODE,
    REG_PDCLK,
    REG_CTRL1,
    REG_CTRL2,
    REG_FIFOCTL,
    REG_FIFOLSB,
    REG_FIFOMSB,
    REG_DPLL,
    REG_IRDIG,
    REG_TEST=15,
};

enum StirModeMask {
    MODE_FIR = 0x80,
    MODE_SIR = 0x20,
    MODE_ASK = 0x10,
    MODE_FASTRX = 0x08,
    MODE_FFRSTEN = 0x04,
    MODE_NRESET = 0x02,
    MODE_2400 = 0x01,
};

enum StirPdclkMask {
    PDCLK_4000000 = 0x02,
    PDCLK_115200 = 0x09,
    PDCLK_57600 = 0x13,
    PDCLK_38400 = 0x1D,
    PDCLK_19200 = 0x3B,
    PDCLK_9600 = 0x77,
    PDCLK_2400 = 0xDF,
};

enum StirCtrl1Mask {
    CTRL1_SDMODE = 0x80,
    CTRL1_RXSLOW = 0x40,
    CTRL1_TXPWD = 0x10,
    CTRL1_RXPWD = 0x08,
    CTRL1_SRESET = 0x01,
};

enum StirCtrl2Mask {
    CTRL2_SPWIDTH = 0x08,
    CTRL2_REVID = 0x03,
};

enum StirFifoCtlMask {
    FIFOCTL_DIR = 0x10,
    FIFOCTL_CLR = 0x08,
    FIFOCTL_EMPTY = 0x04,
};

enum StirDiagMask {
    IRDIG_RXHIGH = 0x80,
    IRDIG_RXLOW = 0x40,
};

enum StirTestMask {
    TEST_PLLDOWN = 0x80,
    TEST_LOOPIR = 0x40,
    TEST_LOOPUSB = 0x20,
    TEST_TSTENA = 0x10,
    TEST_TSTOSC = 0x0F,
};

struct stir_cb {
        struct usb_device *usbdev;      /* init: probe_irda */
        struct net_device *netdev;      /* network layer */
        struct irlap_cb   *irlap;       /* The link layer we are binded to */

        struct qos_info   qos;
    unsigned      speed;    /* Current speed */

        struct task_struct *thread;     /* transmit thread */

    struct sk_buff    *tx_pending;
    void          *io_buf;  /* transmit/receive buffer */
    __u8          *fifo_status;

    iobuff_t      rx_buff;  /* receive unwrap state machine */
    struct timeval    rx_time;
    int       receiving;
    struct urb   *rx_urb;
};


/* These are the currently known USB ids */
static struct usb_device_id dongles[] = {
    /* SigmaTel, Inc,  STIr4200 IrDA/USB Bridge */
    { USB_DEVICE(0x066f, 0x4200) },
    { }
};

MODULE_DEVICE_TABLE(usb, dongles);

/* Send control message to set dongle register */
static int write_reg(struct stir_cb *stir, __u16 reg, __u8 value)
{
    struct usb_device *dev = stir->usbdev;

    pr_debug("%s: write reg %d = 0x%x\n",
         stir->netdev->name, reg, value);
    return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                   REQ_WRITE_SINGLE,
                   USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_DEVICE,
                   value, reg, NULL, 0,
                   CTRL_TIMEOUT);
}

/* Send control message to read multiple registers */
static inline int read_reg(struct stir_cb *stir, __u16 reg,
            __u8 *data, __u16 count)
{
    struct usb_device *dev = stir->usbdev;

    return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                   REQ_READ_REG,
                   USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                   0, reg, data, count,
                   CTRL_TIMEOUT);
}

static inline int isfir(u32 speed)
{
    return speed == 4000000;
}

/*
 * Prepare a FIR IrDA frame for transmission to the USB dongle.  The
 * FIR transmit frame is documented in the datasheet.  It consists of
 * a two byte 0x55 0xAA sequence, two little-endian length bytes, a
 * sequence of exactly 16 XBOF bytes of 0x7E, two BOF bytes of 0x7E,
 * then the data escaped as follows:
 *
 *    0x7D -> 0x7D 0x5D
 *    0x7E -> 0x7D 0x5E
 *    0x7F -> 0x7D 0x5F
 *
 * Then, 4 bytes of little endian (stuffed) FCS follow, then two
 * trailing EOF bytes of 0x7E.
 */
static inline __u8 *stuff_fir(__u8 *p, __u8 c)
{
    switch(c) {
    case 0x7d:
    case 0x7e:
    case 0x7f:
        *p++ = 0x7d;
        c ^= IRDA_TRANS;
        /* fall through */
    default:
        *p++ = c;
    }
    return p;
}

/* Take raw data in skb and put it wrapped into buf */
static unsigned wrap_fir_skb(const struct sk_buff *skb, __u8 *buf)
{
    __u8 *ptr = buf;
    __u32 fcs = ~(crc32_le(~0, skb->data, skb->len));
    __u16 wraplen;
    int i;

    /* Header */
    buf[0] = 0x55;
    buf[1] = 0xAA;

    ptr = buf + STIR_IRDA_HEADER;
    memset(ptr, 0x7f, 16);
    ptr += 16;

    /* BOF */
    *ptr++  = 0x7e;
    *ptr++  = 0x7e;

    /* Address / Control / Information */
    for (i = 0; i < skb->len; i++)
        ptr = stuff_fir(ptr, skb->data[i]);

    /* FCS */
    ptr = stuff_fir(ptr, fcs & 0xff);
    ptr = stuff_fir(ptr, (fcs >> 8) & 0xff);
    ptr = stuff_fir(ptr, (fcs >> 16) & 0xff);
    ptr = stuff_fir(ptr, (fcs >> 24) & 0xff);

    /* EOFs */
    *ptr++ = 0x7e;
    *ptr++ = 0x7e;

    /* Total length, minus the header */
    wraplen = (ptr - buf) - STIR_IRDA_HEADER;
    buf[2] = wraplen & 0xff;
    buf[3] = (wraplen >> 8) & 0xff;

    return wraplen + STIR_IRDA_HEADER;
}

static unsigned wrap_sir_skb(struct sk_buff *skb, __u8 *buf)
{
    __u16 wraplen;

    wraplen = async_wrap_skb(skb, buf + STIR_IRDA_HEADER,
                 STIR_FIFO_SIZE - STIR_IRDA_HEADER);
    buf[0] = 0x55;
    buf[1] = 0xAA;
    buf[2] = wraplen & 0xff;
    buf[3] = (wraplen >> 8) & 0xff;

    return wraplen + STIR_IRDA_HEADER;
}

/*
 * Frame is fully formed in the rx_buff so check crc
 * and pass up to irlap
 * setup for next receive
 */
static void fir_eof(struct stir_cb *stir)
{
    iobuff_t *rx_buff = &stir->rx_buff;
    int len = rx_buff->len - 4;
    struct sk_buff *skb, *nskb;
    __u32 fcs;

    if (unlikely(len <= 0)) {
        pr_debug("%s: short frame len %d\n",
             stir->netdev->name, len);

        ++stir->netdev->stats.rx_errors;
        ++stir->netdev->stats.rx_length_errors;
        return;
    }

    fcs = ~(crc32_le(~0, rx_buff->data, len));
    if (fcs != get_unaligned_le32(rx_buff->data + len)) {
        pr_debug("crc error calc 0x%x len %d\n", fcs, len);
        stir->netdev->stats.rx_errors++;
        stir->netdev->stats.rx_crc_errors++;
        return;
    }

    /* if frame is short then just copy it */
    if (len < IRDA_RX_COPY_THRESHOLD) {
        nskb = dev_alloc_skb(len + 1);
        if (unlikely(!nskb)) {
            ++stir->netdev->stats.rx_dropped;
            return;
        }
        skb_reserve(nskb, 1);
        skb = nskb;
        skb_copy_to_linear_data(nskb, rx_buff->data, len);
    } else {
        nskb = dev_alloc_skb(rx_buff->truesize);
        if (unlikely(!nskb)) {
            ++stir->netdev->stats.rx_dropped;
            return;
        }
        skb_reserve(nskb, 1);
        skb = rx_buff->skb;
        rx_buff->skb = nskb;
        rx_buff->head = nskb->data;
    }

    skb_put(skb, len);

    skb_reset_mac_header(skb);
    skb->protocol = htons(ETH_P_IRDA);
    skb->dev = stir->netdev;

    netif_rx(skb);

    stir->netdev->stats.rx_packets++;
    stir->netdev->stats.rx_bytes += len;

    rx_buff->data = rx_buff->head;
    rx_buff->len = 0;
}

/* Unwrap FIR stuffed data and bump it to IrLAP */
static void stir_fir_chars(struct stir_cb *stir,
                const __u8 *bytes, int len)
{
    iobuff_t *rx_buff = &stir->rx_buff;
    int i;

    for (i = 0; i < len; i++) {
        __u8    byte = bytes[i];

        switch(rx_buff->state) {
        case OUTSIDE_FRAME:
            /* ignore garbage till start of frame */
            if (unlikely(byte != FIR_EOF))
                continue;
            /* Now receiving frame */
            rx_buff->state = BEGIN_FRAME;

            /* Time to initialize receive buffer */
            rx_buff->data = rx_buff->head;
            rx_buff->len = 0;
            continue;

        case LINK_ESCAPE:
            if (byte == FIR_EOF) {
                pr_debug("%s: got EOF after escape\n",
                     stir->netdev->name);
                goto frame_error;
            }
            rx_buff->state = INSIDE_FRAME;
            byte ^= IRDA_TRANS;
            break;

        case BEGIN_FRAME:
            /* ignore multiple BOF/EOF */
            if (byte == FIR_EOF)
                continue;
            rx_buff->state = INSIDE_FRAME;
            rx_buff->in_frame = TRUE;

            /* fall through */
        case INSIDE_FRAME:
            switch(byte) {
            case FIR_CE:
                rx_buff->state = LINK_ESCAPE;
                continue;
            case FIR_XBOF:
                /* 0x7f is not used in this framing */
                pr_debug("%s: got XBOF without escape\n",
                     stir->netdev->name);
                goto frame_error;
            case FIR_EOF:
                rx_buff->state = OUTSIDE_FRAME;
                rx_buff->in_frame = FALSE;
                fir_eof(stir);
                continue;
            }
            break;
        }

        /* add byte to rx buffer */
        if (unlikely(rx_buff->len >= rx_buff->truesize)) {
            pr_debug("%s: fir frame exceeds %d\n",
                 stir->netdev->name, rx_buff->truesize);
            ++stir->netdev->stats.rx_over_errors;
            goto error_recovery;
        }

        rx_buff->data[rx_buff->len++] = byte;
        continue;

    frame_error:
        ++stir->netdev->stats.rx_frame_errors;

    error_recovery:
        ++stir->netdev->stats.rx_errors;
        rx_buff->state = OUTSIDE_FRAME;
        rx_buff->in_frame = FALSE;
    }
}

/* Unwrap SIR stuffed data and bump it up to IrLAP */
static void stir_sir_chars(struct stir_cb *stir,
                const __u8 *bytes, int len)
{
    int i;

    for (i = 0; i < len; i++)
        async_unwrap_char(stir->netdev, &stir->netdev->stats,
                  &stir->rx_buff, bytes[i]);
}

static inline void unwrap_chars(struct stir_cb *stir,
                const __u8 *bytes, int length)
{
    if (isfir(stir->speed))
        stir_fir_chars(stir, bytes, length);
    else
        stir_sir_chars(stir, bytes, length);
}

/* Mode parameters for each speed */
static const struct {
    unsigned speed;
    __u8 pdclk;
} stir_modes[] = {
        { 2400,    PDCLK_2400 },
        { 9600,    PDCLK_9600 },
        { 19200,   PDCLK_19200 },
        { 38400,   PDCLK_38400 },
        { 57600,   PDCLK_57600 },
        { 115200,  PDCLK_115200 },
        { 4000000, PDCLK_4000000 },
};


/*
 * Setup chip for speed.
 *  Called at startup to initialize the chip
 *  and on speed changes.
 *
 * Note: Write multiple registers doesn't appear to work
 */
static int change_speed(struct stir_cb *stir, unsigned speed)
{
    int i, err;
    __u8 mode;

    for (i = 0; i < ARRAY_SIZE(stir_modes); ++i) {
        if (speed == stir_modes[i].speed)
            goto found;
    }

    dev_warn(&stir->netdev->dev, "invalid speed %d\n", speed);
    return -EINVAL;

 found:
    pr_debug("speed change from %d to %d\n", stir->speed, speed);

    /* Reset modulator */
    err = write_reg(stir, REG_CTRL1, CTRL1_SRESET);
    if (err)
        goto out;

    /* Undocumented magic to tweak the DPLL */
    err = write_reg(stir, REG_DPLL, 0x15);
    if (err)
        goto out;

    /* Set clock */
    err = write_reg(stir, REG_PDCLK, stir_modes[i].pdclk);
    if (err)
        goto out;

    mode = MODE_NRESET | MODE_FASTRX;
    if (isfir(speed))
        mode |= MODE_FIR | MODE_FFRSTEN;
    else
        mode |= MODE_SIR;

    if (speed == 2400)
        mode |= MODE_2400;

    err = write_reg(stir, REG_MODE, mode);
    if (err)
        goto out;

    /* This resets TEMIC style transceiver if any. */
    err = write_reg(stir, REG_CTRL1,
            CTRL1_SDMODE | (tx_power & 3) << 1);
    if (err)
        goto out;

    err = write_reg(stir, REG_CTRL1, (tx_power & 3) << 1);
    if (err)
        goto out;

    /* Reset sensitivity */
    err = write_reg(stir, REG_CTRL2, (rx_sensitivity & 7) << 5);
 out:
    stir->speed = speed;
    return err;
}

/*
 * Called from net/core when new frame is available.
 */
static netdev_tx_t stir_hard_xmit(struct sk_buff *skb,
                    struct net_device *netdev)
{
    struct stir_cb *stir = netdev_priv(netdev);

    netif_stop_queue(netdev);

    /* the IRDA wrapping routines don't deal with non linear skb */
    SKB_LINEAR_ASSERT(skb);

    skb = xchg(&stir->tx_pending, skb);
        wake_up_process(stir->thread);
    
    /* this should never happen unless stop/wakeup problem */
    if (unlikely(skb)) {
        WARN_ON(1);
        dev_kfree_skb(skb);
    }

    return NETDEV_TX_OK;
}

/*
 * Wait for the transmit FIFO to have space for next data
 *
 * If space < 0 then wait till FIFO completely drains.
 * FYI: can take up to 13 seconds at 2400baud.
 */
static int fifo_txwait(struct stir_cb *stir, int space)
{
    int err;
    unsigned long count, status;
    unsigned long prev_count = 0x1fff;

    /* Read FIFO status and count */
    for (;; prev_count = count) {
        err = read_reg(stir, REG_FIFOCTL, stir->fifo_status, 
                   FIFO_REGS_SIZE);
        if (unlikely(err != FIFO_REGS_SIZE)) {
            dev_warn(&stir->netdev->dev,
                 "FIFO register read error: %d\n", err);

            return err;
        }

        status = stir->fifo_status[0];
        count = (unsigned)(stir->fifo_status[2] & 0x1f) << 8 
            | stir->fifo_status[1];

        pr_debug("fifo status 0x%lx count %lu\n", status, count);

        /* is fifo receiving already, or empty */
        if (!(status & FIFOCTL_DIR) ||
            (status & FIFOCTL_EMPTY))
            return 0;

        if (signal_pending(current))
            return -EINTR;

        /* shutting down? */
        if (!netif_running(stir->netdev) ||
            !netif_device_present(stir->netdev))
            return -ESHUTDOWN;

        /* only waiting for some space */
        if (space >= 0 && STIR_FIFO_SIZE - 4 > space + count)
            return 0;

        /* queue confused */
        if (prev_count < count)
            break;

        /* estimate transfer time for remaining chars */
        msleep((count * 8000) / stir->speed);
    }
            
    err = write_reg(stir, REG_FIFOCTL, FIFOCTL_CLR);
    if (err) 
        return err;
    err = write_reg(stir, REG_FIFOCTL, 0);
    if (err)
        return err;

    return 0;
}


/* Wait for turnaround delay before starting transmit.  */
static void turnaround_delay(const struct stir_cb *stir, long us)
{
    long ticks;
    struct timeval now;

    if (us <= 0)
        return;

    do_gettimeofday(&now);
    if (now.tv_sec - stir->rx_time.tv_sec > 0)
        us -= USEC_PER_SEC;
    us -= now.tv_usec - stir->rx_time.tv_usec;
    if (us < 10)
        return;

    ticks = us / (1000000 / HZ);
    if (ticks > 0)
        schedule_timeout_interruptible(1 + ticks);
    else
        udelay(us);
}

/*
 * Start receiver by submitting a request to the receive pipe.
 * If nothing is available it will return after rx_interval.
 */
static int receive_start(struct stir_cb *stir)
{
    /* reset state */
    stir->receiving = 1;

    stir->rx_buff.in_frame = FALSE;
    stir->rx_buff.state = OUTSIDE_FRAME;

    stir->rx_urb->status = 0;
    return usb_submit_urb(stir->rx_urb, GFP_KERNEL);
}

/* Stop all pending receive Urb's */
static void receive_stop(struct stir_cb *stir)
{
    stir->receiving = 0;
    usb_kill_urb(stir->rx_urb);

    if (stir->rx_buff.in_frame) 
        stir->netdev->stats.collisions++;
}
/*
 * Wrap data in socket buffer and send it.
 */
static void stir_send(struct stir_cb *stir, struct sk_buff *skb)
{
    unsigned wraplen;
    int first_frame = 0;

    /* if receiving, need to turnaround */
    if (stir->receiving) {
        receive_stop(stir);
        turnaround_delay(stir, irda_get_mtt(skb));
        first_frame = 1;
    }

    if (isfir(stir->speed))
        wraplen = wrap_fir_skb(skb, stir->io_buf);
    else
        wraplen = wrap_sir_skb(skb, stir->io_buf);
        
    /* check for space available in fifo */
    if (!first_frame)
        fifo_txwait(stir, wraplen);

    stir->netdev->stats.tx_packets++;
    stir->netdev->stats.tx_bytes += skb->len;
    stir->netdev->trans_start = jiffies;
    pr_debug("send %d (%d)\n", skb->len, wraplen);

    if (usb_bulk_msg(stir->usbdev, usb_sndbulkpipe(stir->usbdev, 1),
             stir->io_buf, wraplen,
             NULL, TRANSMIT_TIMEOUT))
        stir->netdev->stats.tx_errors++;
}

/*
 * Transmit state machine thread
 */
static int stir_transmit_thread(void *arg)
{
    struct stir_cb *stir = arg;
    struct net_device *dev = stir->netdev;
    struct sk_buff *skb;

        while (!kthread_should_stop()) {
#ifdef CONFIG_PM
        /* if suspending, then power off and wait */
        if (unlikely(freezing(current))) {
            if (stir->receiving)
                receive_stop(stir);
            else
                fifo_txwait(stir, -1);

            write_reg(stir, REG_CTRL1, CTRL1_TXPWD|CTRL1_RXPWD);

            try_to_freeze();

            if (change_speed(stir, stir->speed))
                break;
        }
#endif

        /* if something to send? */
        skb = xchg(&stir->tx_pending, NULL);
        if (skb) {
            unsigned new_speed = irda_get_next_speed(skb);
            netif_wake_queue(dev);

            if (skb->len > 0)
                stir_send(stir, skb);
            dev_kfree_skb(skb);

            if ((new_speed != -1) && (stir->speed != new_speed)) {
                if (fifo_txwait(stir, -1) ||
                    change_speed(stir, new_speed))
                    break;
            }
            continue;
        }

        /* nothing to send? start receiving */
        if (!stir->receiving &&
            irda_device_txqueue_empty(dev)) {
            /* Wait otherwise chip gets confused. */
            if (fifo_txwait(stir, -1))
                break;

            if (unlikely(receive_start(stir))) {
                if (net_ratelimit())
                    dev_info(&dev->dev,
                         "%s: receive usb submit failed\n",
                         stir->netdev->name);
                stir->receiving = 0;
                msleep(10);
                continue;
            }
        }

        /* sleep if nothing to send */
                set_current_state(TASK_INTERRUPTIBLE);
                schedule();

    }
        return 0;
}


/*
 * USB bulk receive completion callback.
 * Wakes up every ms (usb round trip) with wrapped 
 * data.
 */
static void stir_rcv_irq(struct urb *urb)
{
    struct stir_cb *stir = urb->context;
    int err;

    /* in process of stopping, just drop data */
    if (!netif_running(stir->netdev))
        return;

    /* unlink, shutdown, unplug, other nasties */
    if (urb->status != 0) 
        return;

    if (urb->actual_length > 0) {
        pr_debug("receive %d\n", urb->actual_length);
        unwrap_chars(stir, urb->transfer_buffer,
                 urb->actual_length);
        
        do_gettimeofday(&stir->rx_time);
    }

    /* kernel thread is stopping receiver don't resubmit */
    if (!stir->receiving)
        return;

    /* resubmit existing urb */
    err = usb_submit_urb(urb, GFP_ATOMIC);

    /* in case of error, the kernel thread will restart us */
    if (err) {
        dev_warn(&stir->netdev->dev, "usb receive submit error: %d\n",
             err);
        stir->receiving = 0;
        wake_up_process(stir->thread);
    }
}

/*
 * Function stir_net_open (dev)
 *
 *    Network device is taken up. Usually this is done by "ifconfig irda0 up"
 */
static int stir_net_open(struct net_device *netdev)
{
    struct stir_cb *stir = netdev_priv(netdev);
    int err;
    char hwname[16];

    err = usb_clear_halt(stir->usbdev, usb_sndbulkpipe(stir->usbdev, 1));
    if (err)
        goto err_out1;
    err = usb_clear_halt(stir->usbdev, usb_rcvbulkpipe(stir->usbdev, 2));
    if (err)
        goto err_out1;

    err = change_speed(stir, 9600);
    if (err)
        goto err_out1;

    err = -ENOMEM;

    /* Initialize for SIR/FIR to copy data directly into skb.  */
    stir->receiving = 0;
    stir->rx_buff.truesize = IRDA_SKB_MAX_MTU;
    stir->rx_buff.skb = dev_alloc_skb(IRDA_SKB_MAX_MTU);
    if (!stir->rx_buff.skb) 
        goto err_out1;

    skb_reserve(stir->rx_buff.skb, 1);
    stir->rx_buff.head = stir->rx_buff.skb->data;
    do_gettimeofday(&stir->rx_time);

    stir->rx_urb = usb_alloc_urb(0, GFP_KERNEL);
    if (!stir->rx_urb) 
        goto err_out2;

    stir->io_buf = kmalloc(STIR_FIFO_SIZE, GFP_KERNEL);
    if (!stir->io_buf)
        goto err_out3;

    usb_fill_bulk_urb(stir->rx_urb, stir->usbdev,
              usb_rcvbulkpipe(stir->usbdev, 2),
              stir->io_buf, STIR_FIFO_SIZE,
              stir_rcv_irq, stir);

    stir->fifo_status = kmalloc(FIFO_REGS_SIZE, GFP_KERNEL);
    if (!stir->fifo_status) 
        goto err_out4;
        
    /*
     * Now that everything should be initialized properly,
     * Open new IrLAP layer instance to take care of us...
     * Note : will send immediately a speed change...
     */
    sprintf(hwname, "usb#%d", stir->usbdev->devnum);
    stir->irlap = irlap_open(netdev, &stir->qos, hwname);
    if (!stir->irlap) {
        dev_err(&stir->usbdev->dev, "irlap_open failed\n");
        goto err_out5;
    }

    stir->thread = kthread_run(stir_transmit_thread, stir,
                   "%s", stir->netdev->name);
        if (IS_ERR(stir->thread)) {
                err = PTR_ERR(stir->thread);
        dev_err(&stir->usbdev->dev, "unable to start kernel thread\n");
        goto err_out6;
    }

    netif_start_queue(netdev);

    return 0;

 err_out6:
    irlap_close(stir->irlap);
 err_out5:
    kfree(stir->fifo_status);
 err_out4:
    kfree(stir->io_buf);
 err_out3:
    usb_free_urb(stir->rx_urb);
 err_out2:
    kfree_skb(stir->rx_buff.skb);
 err_out1:
    return err;
}

/*
 * Function stir_net_close (stir)
 *
 *    Network device is taken down. Usually this is done by
 *    "ifconfig irda0 down"
 */
static int stir_net_close(struct net_device *netdev)
{
    struct stir_cb *stir = netdev_priv(netdev);

    /* Stop transmit processing */
    netif_stop_queue(netdev);

    /* Kill transmit thread */
    kthread_stop(stir->thread);
    kfree(stir->fifo_status);

    /* Mop up receive urb's */
    usb_kill_urb(stir->rx_urb);
    
    kfree(stir->io_buf);
    usb_free_urb(stir->rx_urb);
    kfree_skb(stir->rx_buff.skb);

    /* Stop and remove instance of IrLAP */
    if (stir->irlap)
        irlap_close(stir->irlap);

    stir->irlap = NULL;

    return 0;
}

/*
 * IOCTLs : Extra out-of-band network commands...
 */
static int stir_net_ioctl(struct net_device *netdev, struct ifreq *rq, int cmd)
{
    struct if_irda_req *irq = (struct if_irda_req *) rq;
    struct stir_cb *stir = netdev_priv(netdev);
    int ret = 0;

    switch (cmd) {
    case SIOCSBANDWIDTH: /* Set bandwidth */
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;

        /* Check if the device is still there */
        if (netif_device_present(stir->netdev))
            ret = change_speed(stir, irq->ifr_baudrate);
        break;

    case SIOCSMEDIABUSY: /* Set media busy */
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;

        /* Check if the IrDA stack is still there */
        if (netif_running(stir->netdev))
            irda_device_set_media_busy(stir->netdev, TRUE);
        break;

    case SIOCGRECEIVING:
        /* Only approximately true */
        irq->ifr_receiving = stir->receiving;
        break;

    default:
        ret = -EOPNOTSUPP;
    }

    return ret;
}

static const struct net_device_ops stir_netdev_ops = {
    .ndo_open       = stir_net_open,
    .ndo_stop       = stir_net_close,
    .ndo_start_xmit = stir_hard_xmit,
    .ndo_do_ioctl   = stir_net_ioctl,
};

/*
 * This routine is called by the USB subsystem for each new device
 * in the system. We need to check if the device is ours, and in
 * this case start handling it.
 * Note : it might be worth protecting this function by a global
 * spinlock... Or not, because maybe USB already deal with that...
 */
static int stir_probe(struct usb_interface *intf,
              const struct usb_device_id *id)
{
    struct usb_device *dev = interface_to_usbdev(intf);
    struct stir_cb *stir = NULL;
    struct net_device *net;
    int ret = -ENOMEM;

    /* Allocate network device container. */
    net = alloc_irdadev(sizeof(*stir));
    if(!net)
        goto err_out1;

    SET_NETDEV_DEV(net, &intf->dev);
    stir = netdev_priv(net);
    stir->netdev = net;
    stir->usbdev = dev;

    ret = usb_reset_configuration(dev);
    if (ret != 0) {
        dev_err(&intf->dev, "usb reset configuration failed\n");
        goto err_out2;
    }

    printk(KERN_INFO "SigmaTel STIr4200 IRDA/USB found at address %d, "
        "Vendor: %x, Product: %x\n",
           dev->devnum, le16_to_cpu(dev->descriptor.idVendor),
           le16_to_cpu(dev->descriptor.idProduct));

    /* Initialize QoS for this device */
    irda_init_max_qos_capabilies(&stir->qos);

    /* That's the Rx capability. */
    stir->qos.baud_rate.bits       &= IR_2400 | IR_9600 | IR_19200 |
                     IR_38400 | IR_57600 | IR_115200 |
                     (IR_4000000 << 8);
    stir->qos.min_turn_time.bits   &= qos_mtt_bits;
    irda_qos_bits_to_value(&stir->qos);

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

    ret = register_netdev(net);
    if (ret != 0)
        goto err_out2;

    dev_info(&intf->dev, "IrDA: Registered SigmaTel device %s\n",
         net->name);

    usb_set_intfdata(intf, stir);

    return 0;

err_out2:
    free_netdev(net);
err_out1:
    return ret;
}

/*
 * The current device is removed, the USB layer tell us to shut it down...
 */
static void stir_disconnect(struct usb_interface *intf)
{
    struct stir_cb *stir = usb_get_intfdata(intf);

    if (!stir)
        return;

    unregister_netdev(stir->netdev);
    free_netdev(stir->netdev);

    usb_set_intfdata(intf, NULL);
}

#ifdef CONFIG_PM
/* USB suspend, so power off the transmitter/receiver */
static int stir_suspend(struct usb_interface *intf, pm_message_t message)
{
    struct stir_cb *stir = usb_get_intfdata(intf);

    netif_device_detach(stir->netdev);
    return 0;
}

/* Coming out of suspend, so reset hardware */
static int stir_resume(struct usb_interface *intf)
{
    struct stir_cb *stir = usb_get_intfdata(intf);

    netif_device_attach(stir->netdev);

    /* receiver restarted when send thread wakes up */
    return 0;
}
#endif

/*
 * USB device callbacks
 */
static struct usb_driver irda_driver = {
    .name       = "stir4200",
    .probe      = stir_probe,
    .disconnect = stir_disconnect,
    .id_table   = dongles,
#ifdef CONFIG_PM
    .suspend    = stir_suspend,
    .resume     = stir_resume,
#endif
};

module_usb_driver(irda_driver);