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stir4200.c

/*****************************************************************************
*
* Filename:      stir4200.c
* Version:       0.4
* Description:   Irda SigmaTel USB Dongle
* Status:        Experimental
* Author:        Stephen Hemminger <shemminger@osdl.org>
*
*     Based on earlier driver by Paul Stewart <stewart@parc.com>
*
*     Copyright (C) 2000, Roman Weissgaerber <weissg@vienna.at>
*     Copyright (C) 2001, Dag Brattli <dag@brattli.net>
*     Copyright (C) 2001, Jean Tourrilhes <jt@hpl.hp.com>
*     Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org>
*
*     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 <shemminger@linux-foundation.org>");
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 net_device_stats stats;    /* network statistics */
        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->stats.rx_errors;
            ++stir->stats.rx_length_errors;
            return;
      }

      fcs = ~(crc32_le(~0, rx_buff->data, len));
      if (fcs != le32_to_cpu(get_unaligned((__le32 *)(rx_buff->data+len)))) {
            pr_debug("crc error calc 0x%x len %d\n", fcs, len);
            stir->stats.rx_errors++;
            stir->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->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->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->stats.rx_packets++;
      stir->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->stats.rx_over_errors;
                  goto error_recovery;
            }

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

      frame_error:
            ++stir->stats.rx_frame_errors;

      error_recovery:
            ++stir->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->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;
      }

      warn("%s: invalid speed %d", stir->netdev->name, 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 int 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 0;
}

/*
 * 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)) {
                  warn("%s: FIFO register read error: %d", 
                       stir->netdev->name, 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->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->stats.tx_packets++;
      stir->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->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);

                  refrigerator();

                  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())
                              info("%s: receive usb submit failed",
                                   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);
            
            stir->netdev->last_rx = jiffies;
            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) {
            warn("%s: usb receive submit error: %d",
                  stir->netdev->name, 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) {
            err("stir4200: irlap_open failed");
            goto err_out5;
      }

      /** Start kernel thread for transmit.  */
      stir->thread = kthread_run(stir_transmit_thread, stir,
                           "%s", stir->netdev->name);
        if (IS_ERR(stir->thread)) {
                err = PTR_ERR(stir->thread);
            err("stir4200: unable to start kernel thread");
            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;
}

/*
 * Get device stats (for /proc/net/dev and ifconfig)
 */
static struct net_device_stats *stir_net_get_stats(struct net_device *netdev)
{
      struct stir_cb *stir = netdev_priv(netdev);
      return &stir->stats;
}

/*
 * 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) {
            err("stir4200: usb reset configuration failed");
            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->hard_start_xmit = stir_hard_xmit;
      net->open            = stir_net_open;
      net->stop            = stir_net_close;
      net->get_stats         = stir_net_get_stats;
      net->do_ioctl        = stir_net_ioctl;

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

      info("IrDA: Registered SigmaTel device %s", 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 insertion
 */
static int __init stir_init(void)
{
      return usb_register(&irda_driver);
}
module_init(stir_init);

/*
 * Module removal
 */
static void __exit stir_cleanup(void)
{
      /* Deregister the driver and remove all pending instances */
      usb_deregister(&irda_driver);
}
module_exit(stir_cleanup);

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