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iowarrior.c

/*
 *  Native support for the I/O-Warrior USB devices
 *
 *  Copyright (c) 2003-2005  Code Mercenaries GmbH
 *  written by Christian Lucht <lucht@codemercs.com>
 *
 *  based on

 *  usb-skeleton.c by Greg Kroah-Hartman  <greg@kroah.com>
 *  brlvger.c by Stephane Dalton  <sdalton@videotron.ca>
 *           and St�hane Doyon   <s.doyon@videotron.ca>
 *
 *  Released under the GPLv2.
 */

#include <linux/module.h>
#include <linux/usb.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/version.h>
#include <linux/usb/iowarrior.h>

/* Version Information */
#define DRIVER_VERSION "v0.4.0"
#define DRIVER_AUTHOR "Christian Lucht <lucht@codemercs.com>"
#define DRIVER_DESC "USB IO-Warrior driver (Linux 2.6.x)"

#define USB_VENDOR_ID_CODEMERCS           1984
/* low speed iowarrior */
#define USB_DEVICE_ID_CODEMERCS_IOW40     0x1500
#define USB_DEVICE_ID_CODEMERCS_IOW24     0x1501
#define USB_DEVICE_ID_CODEMERCS_IOWPV1    0x1511
#define USB_DEVICE_ID_CODEMERCS_IOWPV2    0x1512
/* full speed iowarrior */
#define USB_DEVICE_ID_CODEMERCS_IOW56     0x1503

/* Get a minor range for your devices from the usb maintainer */
#ifdef CONFIG_USB_DYNAMIC_MINORS
#define IOWARRIOR_MINOR_BASE  0
#else
#define IOWARRIOR_MINOR_BASE  208   // SKELETON_MINOR_BASE 192 + 16, not offical yet
#endif

/* interrupt input queue size */
#define MAX_INTERRUPT_BUFFER 16
/*
   maximum number of urbs that are submitted for writes at the same time,
   this applies to the IOWarrior56 only!
   IOWarrior24 and IOWarrior40 use synchronous usb_control_msg calls.
*/
#define MAX_WRITES_IN_FLIGHT 4

/* Use our own dbg macro */
#undef dbg
#define dbg( format, arg... ) do { if( debug ) printk( KERN_DEBUG __FILE__ ": " format "\n" , ## arg ); } while ( 0 )

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/* Module parameters */
static int debug = 0;
module_param(debug, bool, 0644);
MODULE_PARM_DESC(debug, "debug=1 enables debugging messages");

static struct usb_driver iowarrior_driver;
static DEFINE_MUTEX(iowarrior_open_disc_lock);

/*--------------*/
/*     data     */
/*--------------*/

/* Structure to hold all of our device specific stuff */
struct iowarrior {
      struct mutex mutex;                 /* locks this structure */
      struct usb_device *udev;            /* save off the usb device pointer */
      struct usb_interface *interface;    /* the interface for this device */
      unsigned char minor;                /* the starting minor number for this device */
      struct usb_endpoint_descriptor *int_out_endpoint;     /* endpoint for reading (needed for IOW56 only) */
      struct usb_endpoint_descriptor *int_in_endpoint;      /* endpoint for reading */
      struct urb *int_in_urb;       /* the urb for reading data */
      unsigned char *int_in_buffer; /* buffer for data to be read */
      unsigned char serial_number;  /* to detect lost packages */
      unsigned char *read_queue;    /* size is MAX_INTERRUPT_BUFFER * packet size */
      wait_queue_head_t read_wait;
      wait_queue_head_t write_wait; /* wait-queue for writing to the device */
      atomic_t write_busy;          /* number of write-urbs submitted */
      atomic_t read_idx;
      atomic_t intr_idx;
      spinlock_t intr_idx_lock;     /* protects intr_idx */
      atomic_t overflow_flag;       /* signals an index 'rollover' */
      int present;                  /* this is 1 as long as the device is connected */
      int opened;             /* this is 1 if the device is currently open */
      char chip_serial[9];          /* the serial number string of the chip connected */
      int report_size;        /* number of bytes in a report */
      u16 product_id;
};

/*--------------*/
/*    globals   */
/*--------------*/

/*
 *  USB spec identifies 5 second timeouts.
 */
#define GET_TIMEOUT 5
#define USB_REQ_GET_REPORT  0x01
//#if 0
static int usb_get_report(struct usb_device *dev,
                    struct usb_host_interface *inter, unsigned char type,
                    unsigned char id, void *buf, int size)
{
      return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                         USB_REQ_GET_REPORT,
                         USB_DIR_IN | USB_TYPE_CLASS |
                         USB_RECIP_INTERFACE, (type << 8) + id,
                         inter->desc.bInterfaceNumber, buf, size,
                         GET_TIMEOUT*HZ);
}
//#endif

#define USB_REQ_SET_REPORT 0x09

static int usb_set_report(struct usb_interface *intf, unsigned char type,
                    unsigned char id, void *buf, int size)
{
      return usb_control_msg(interface_to_usbdev(intf),
                         usb_sndctrlpipe(interface_to_usbdev(intf), 0),
                         USB_REQ_SET_REPORT,
                         USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                         (type << 8) + id,
                         intf->cur_altsetting->desc.bInterfaceNumber, buf,
                         size, HZ);
}

/*---------------------*/
/* driver registration */
/*---------------------*/
/* table of devices that work with this driver */
static struct usb_device_id iowarrior_ids[] = {
      {USB_DEVICE(USB_VENDOR_ID_CODEMERCS, USB_DEVICE_ID_CODEMERCS_IOW40)},
      {USB_DEVICE(USB_VENDOR_ID_CODEMERCS, USB_DEVICE_ID_CODEMERCS_IOW24)},
      {USB_DEVICE(USB_VENDOR_ID_CODEMERCS, USB_DEVICE_ID_CODEMERCS_IOWPV1)},
      {USB_DEVICE(USB_VENDOR_ID_CODEMERCS, USB_DEVICE_ID_CODEMERCS_IOWPV2)},
      {USB_DEVICE(USB_VENDOR_ID_CODEMERCS, USB_DEVICE_ID_CODEMERCS_IOW56)},
      {}                /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, iowarrior_ids);

/*
 * USB callback handler for reading data
 */
static void iowarrior_callback(struct urb *urb)
{
      struct iowarrior *dev = (struct iowarrior *)urb->context;
      int intr_idx;
      int read_idx;
      int aux_idx;
      int offset;
      int status = urb->status;
      int retval;

      switch (status) {
      case 0:
            /* success */
            break;
      case -ECONNRESET:
      case -ENOENT:
      case -ESHUTDOWN:
            return;
      default:
            goto exit;
      }

      spin_lock(&dev->intr_idx_lock);
      intr_idx = atomic_read(&dev->intr_idx);
      /* aux_idx become previous intr_idx */
      aux_idx = (intr_idx == 0) ? (MAX_INTERRUPT_BUFFER - 1) : (intr_idx - 1);
      read_idx = atomic_read(&dev->read_idx);

      /* queue is not empty and it's interface 0 */
      if ((intr_idx != read_idx)
          && (dev->interface->cur_altsetting->desc.bInterfaceNumber == 0)) {
            /* + 1 for serial number */
            offset = aux_idx * (dev->report_size + 1);
            if (!memcmp
                (dev->read_queue + offset, urb->transfer_buffer,
                 dev->report_size)) {
                  /* equal values on interface 0 will be ignored */
                  spin_unlock(&dev->intr_idx_lock);
                  goto exit;
            }
      }

      /* aux_idx become next intr_idx */
      aux_idx = (intr_idx == (MAX_INTERRUPT_BUFFER - 1)) ? 0 : (intr_idx + 1);
      if (read_idx == aux_idx) {
            /* queue full, dropping oldest input */
            read_idx = (++read_idx == MAX_INTERRUPT_BUFFER) ? 0 : read_idx;
            atomic_set(&dev->read_idx, read_idx);
            atomic_set(&dev->overflow_flag, 1);
      }

      /* +1 for serial number */
      offset = intr_idx * (dev->report_size + 1);
      memcpy(dev->read_queue + offset, urb->transfer_buffer,
             dev->report_size);
      *(dev->read_queue + offset + (dev->report_size)) = dev->serial_number++;

      atomic_set(&dev->intr_idx, aux_idx);
      spin_unlock(&dev->intr_idx_lock);
      /* tell the blocking read about the new data */
      wake_up_interruptible(&dev->read_wait);

exit:
      retval = usb_submit_urb(urb, GFP_ATOMIC);
      if (retval)
            dev_err(&dev->interface->dev, "%s - usb_submit_urb failed with result %d\n",
                  __FUNCTION__, retval);

}

/*
 * USB Callback handler for write-ops
 */
static void iowarrior_write_callback(struct urb *urb)
{
      struct iowarrior *dev;
      int status = urb->status;

      dev = (struct iowarrior *)urb->context;
      /* sync/async unlink faults aren't errors */
      if (status &&
          !(status == -ENOENT ||
            status == -ECONNRESET || status == -ESHUTDOWN)) {
            dbg("%s - nonzero write bulk status received: %d",
                __func__, status);
      }
      /* free up our allocated buffer */
      usb_buffer_free(urb->dev, urb->transfer_buffer_length,
                  urb->transfer_buffer, urb->transfer_dma);
      /* tell a waiting writer the interrupt-out-pipe is available again */
      atomic_dec(&dev->write_busy);
      wake_up_interruptible(&dev->write_wait);
}

/**
 *    iowarrior_delete
 */
static inline void iowarrior_delete(struct iowarrior *dev)
{
      dbg("%s - minor %d", __func__, dev->minor);
      kfree(dev->int_in_buffer);
      usb_free_urb(dev->int_in_urb);
      kfree(dev->read_queue);
      kfree(dev);
}

/*---------------------*/
/* fops implementation */
/*---------------------*/

static int read_index(struct iowarrior *dev)
{
      int intr_idx, read_idx;

      read_idx = atomic_read(&dev->read_idx);
      intr_idx = atomic_read(&dev->intr_idx);

      return (read_idx == intr_idx ? -1 : read_idx);
}

/**
 *  iowarrior_read
 */
static ssize_t iowarrior_read(struct file *file, char __user *buffer,
                        size_t count, loff_t *ppos)
{
      struct iowarrior *dev;
      int read_idx;
      int offset;

      dev = (struct iowarrior *)file->private_data;

      /* verify that the device wasn't unplugged */
      if (dev == NULL || !dev->present)
            return -ENODEV;

      dbg("%s - minor %d, count = %zd", __func__, dev->minor, count);

      /* read count must be packet size (+ time stamp) */
      if ((count != dev->report_size)
          && (count != (dev->report_size + 1)))
            return -EINVAL;

      /* repeat until no buffer overrun in callback handler occur */
      do {
            atomic_set(&dev->overflow_flag, 0);
            if ((read_idx = read_index(dev)) == -1) {
                  /* queue emty */
                  if (file->f_flags & O_NONBLOCK)
                        return -EAGAIN;
                  else {
                        //next line will return when there is either new data, or the device is unplugged
                        int r = wait_event_interruptible(dev->read_wait,
                                                 (!dev->present
                                                  || (read_idx =
                                                      read_index
                                                      (dev)) !=
                                                  -1));
                        if (r) {
                              //we were interrupted by a signal
                              return -ERESTART;
                        }
                        if (!dev->present) {
                              //The device was unplugged
                              return -ENODEV;
                        }
                        if (read_idx == -1) {
                              // Can this happen ???
                              return 0;
                        }
                  }
            }

            offset = read_idx * (dev->report_size + 1);
            if (copy_to_user(buffer, dev->read_queue + offset, count)) {
                  return -EFAULT;
            }
      } while (atomic_read(&dev->overflow_flag));

      read_idx = ++read_idx == MAX_INTERRUPT_BUFFER ? 0 : read_idx;
      atomic_set(&dev->read_idx, read_idx);
      return count;
}

/*
 * iowarrior_write
 */
static ssize_t iowarrior_write(struct file *file,
                         const char __user *user_buffer,
                         size_t count, loff_t *ppos)
{
      struct iowarrior *dev;
      int retval = 0;
      char *buf = NULL; /* for IOW24 and IOW56 we need a buffer */
      struct urb *int_out_urb = NULL;

      dev = (struct iowarrior *)file->private_data;

      mutex_lock(&dev->mutex);
      /* verify that the device wasn't unplugged */
      if (!dev->present) {
            retval = -ENODEV;
            goto exit;
      }
      dbg("%s - minor %d, count = %zd", __func__, dev->minor, count);
      /* if count is 0 we're already done */
      if (count == 0) {
            retval = 0;
            goto exit;
      }
      /* We only accept full reports */
      if (count != dev->report_size) {
            retval = -EINVAL;
            goto exit;
      }
      switch (dev->product_id) {
      case USB_DEVICE_ID_CODEMERCS_IOW24:
      case USB_DEVICE_ID_CODEMERCS_IOWPV1:
      case USB_DEVICE_ID_CODEMERCS_IOWPV2:
      case USB_DEVICE_ID_CODEMERCS_IOW40:
            /* IOW24 and IOW40 use a synchronous call */
            buf = kmalloc(8, GFP_KERNEL); /* 8 bytes are enough for both products */
            if (!buf) {
                  retval = -ENOMEM;
                  goto exit;
            }
            if (copy_from_user(buf, user_buffer, count)) {
                  retval = -EFAULT;
                  kfree(buf);
                  goto exit;
            }
            retval = usb_set_report(dev->interface, 2, 0, buf, count);
            kfree(buf);
            goto exit;
            break;
      case USB_DEVICE_ID_CODEMERCS_IOW56:
            /* The IOW56 uses asynchronous IO and more urbs */
            if (atomic_read(&dev->write_busy) == MAX_WRITES_IN_FLIGHT) {
                  /* Wait until we are below the limit for submitted urbs */
                  if (file->f_flags & O_NONBLOCK) {
                        retval = -EAGAIN;
                        goto exit;
                  } else {
                        retval = wait_event_interruptible(dev->write_wait,
                                                  (!dev->present || (atomic_read (&dev-> write_busy) < MAX_WRITES_IN_FLIGHT)));
                        if (retval) {
                              /* we were interrupted by a signal */
                              retval = -ERESTART;
                              goto exit;
                        }
                        if (!dev->present) {
                              /* The device was unplugged */
                              retval = -ENODEV;
                              goto exit;
                        }
                        if (!dev->opened) {
                              /* We were closed while waiting for an URB */
                              retval = -ENODEV;
                              goto exit;
                        }
                  }
            }
            atomic_inc(&dev->write_busy);
            int_out_urb = usb_alloc_urb(0, GFP_KERNEL);
            if (!int_out_urb) {
                  retval = -ENOMEM;
                  dbg("%s Unable to allocate urb ", __func__);
                  goto error_no_urb;
            }
            buf = usb_buffer_alloc(dev->udev, dev->report_size,
                               GFP_KERNEL, &int_out_urb->transfer_dma);
            if (!buf) {
                  retval = -ENOMEM;
                  dbg("%s Unable to allocate buffer ", __func__);
                  goto error_no_buffer;
            }
            usb_fill_int_urb(int_out_urb, dev->udev,
                         usb_sndintpipe(dev->udev,
                                    dev->int_out_endpoint->bEndpointAddress),
                         buf, dev->report_size,
                         iowarrior_write_callback, dev,
                         dev->int_out_endpoint->bInterval);
            int_out_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
            if (copy_from_user(buf, user_buffer, count)) {
                  retval = -EFAULT;
                  goto error;
            }
            retval = usb_submit_urb(int_out_urb, GFP_KERNEL);
            if (retval) {
                  dbg("%s submit error %d for urb nr.%d", __func__,
                      retval, atomic_read(&dev->write_busy));
                  goto error;
            }
            /* submit was ok */
            retval = count;
            usb_free_urb(int_out_urb);
            goto exit;
            break;
      default:
            /* what do we have here ? An unsupported Product-ID ? */
            dev_err(&dev->interface->dev, "%s - not supported for product=0x%x\n",
                  __FUNCTION__, dev->product_id);
            retval = -EFAULT;
            goto exit;
            break;
      }
error:
      usb_buffer_free(dev->udev, dev->report_size, buf,
                  int_out_urb->transfer_dma);
error_no_buffer:
      usb_free_urb(int_out_urb);
error_no_urb:
      atomic_dec(&dev->write_busy);
      wake_up_interruptible(&dev->write_wait);
exit:
      mutex_unlock(&dev->mutex);
      return retval;
}

/**
 *    iowarrior_ioctl
 */
static int iowarrior_ioctl(struct inode *inode, struct file *file,
                     unsigned int cmd, unsigned long arg)
{
      struct iowarrior *dev = NULL;
      __u8 *buffer;
      __u8 __user *user_buffer;
      int retval;
      int io_res;       /* checks for bytes read/written and copy_to/from_user results */

      dev = (struct iowarrior *)file->private_data;
      if (dev == NULL) {
            return -ENODEV;
      }

      buffer = kzalloc(dev->report_size, GFP_KERNEL);
      if (!buffer)
            return -ENOMEM;

      /* lock this object */
      mutex_lock(&dev->mutex);

      /* verify that the device wasn't unplugged */
      if (!dev->present) {
            retval = -ENODEV;
            goto error_out;
      }

      dbg("%s - minor %d, cmd 0x%.4x, arg %ld", __func__, dev->minor, cmd,
          arg);

      retval = 0;
      io_res = 0;
      switch (cmd) {
      case IOW_WRITE:
            if (dev->product_id == USB_DEVICE_ID_CODEMERCS_IOW24 ||
                dev->product_id == USB_DEVICE_ID_CODEMERCS_IOWPV1 ||
                dev->product_id == USB_DEVICE_ID_CODEMERCS_IOWPV2 ||
                dev->product_id == USB_DEVICE_ID_CODEMERCS_IOW40) {
                  user_buffer = (__u8 __user *)arg;
                  io_res = copy_from_user(buffer, user_buffer,
                                    dev->report_size);
                  if (io_res) {
                        retval = -EFAULT;
                  } else {
                        io_res = usb_set_report(dev->interface, 2, 0,
                                          buffer,
                                          dev->report_size);
                        if (io_res < 0)
                              retval = io_res;
                  }
            } else {
                  retval = -EINVAL;
                  dev_err(&dev->interface->dev,
                        "ioctl 'IOW_WRITE' is not supported for product=0x%x.\n",
                        dev->product_id);
            }
            break;
      case IOW_READ:
            user_buffer = (__u8 __user *)arg;
            io_res = usb_get_report(dev->udev,
                              dev->interface->cur_altsetting, 1, 0,
                              buffer, dev->report_size);
            if (io_res < 0)
                  retval = io_res;
            else {
                  io_res = copy_to_user(user_buffer, buffer, dev->report_size);
                  if (io_res < 0)
                        retval = -EFAULT;
            }
            break;
      case IOW_GETINFO:
            {
                  /* Report available information for the device */
                  struct iowarrior_info info;
                  /* needed for power consumption */
                  struct usb_config_descriptor *cfg_descriptor = &dev->udev->actconfig->desc;

                  /* directly from the descriptor */
                  info.vendor = le16_to_cpu(dev->udev->descriptor.idVendor);
                  info.product = dev->product_id;
                  info.revision = le16_to_cpu(dev->udev->descriptor.bcdDevice);

                  /* 0==UNKNOWN, 1==LOW(usb1.1) ,2=FULL(usb1.1), 3=HIGH(usb2.0) */
                  info.speed = le16_to_cpu(dev->udev->speed);
                  info.if_num = dev->interface->cur_altsetting->desc.bInterfaceNumber;
                  info.report_size = dev->report_size;

                  /* serial number string has been read earlier 8 chars or empty string */
                  memcpy(info.serial, dev->chip_serial,
                         sizeof(dev->chip_serial));
                  if (cfg_descriptor == NULL) {
                        info.power = -1;  /* no information available */
                  } else {
                        /* the MaxPower is stored in units of 2mA to make it fit into a byte-value */
                        info.power = cfg_descriptor->bMaxPower * 2;
                  }
                  io_res = copy_to_user((struct iowarrior_info __user *)arg, &info,
                               sizeof(struct iowarrior_info));
                  if (io_res < 0)
                        retval = -EFAULT;
                  break;
            }
      default:
            /* return that we did not understand this ioctl call */
            retval = -ENOTTY;
            break;
      }
error_out:
      /* unlock the device */
      mutex_unlock(&dev->mutex);
      kfree(buffer);
      return retval;
}

/**
 *    iowarrior_open
 */
static int iowarrior_open(struct inode *inode, struct file *file)
{
      struct iowarrior *dev = NULL;
      struct usb_interface *interface;
      int subminor;
      int retval = 0;

      dbg("%s", __func__);

      subminor = iminor(inode);

      interface = usb_find_interface(&iowarrior_driver, subminor);
      if (!interface) {
            err("%s - error, can't find device for minor %d", __FUNCTION__,
                subminor);
            return -ENODEV;
      }

      mutex_lock(&iowarrior_open_disc_lock);
      dev = usb_get_intfdata(interface);
      if (!dev) {
            mutex_unlock(&iowarrior_open_disc_lock);
            return -ENODEV;
      }

      mutex_lock(&dev->mutex);
      mutex_unlock(&iowarrior_open_disc_lock);

      /* Only one process can open each device, no sharing. */
      if (dev->opened) {
            retval = -EBUSY;
            goto out;
      }

      /* setup interrupt handler for receiving values */
      if ((retval = usb_submit_urb(dev->int_in_urb, GFP_KERNEL)) < 0) {
            dev_err(&interface->dev, "Error %d while submitting URB\n", retval);
            retval = -EFAULT;
            goto out;
      }
      /* increment our usage count for the driver */
      ++dev->opened;
      /* save our object in the file's private structure */
      file->private_data = dev;
      retval = 0;

out:
      mutex_unlock(&dev->mutex);
      return retval;
}

/**
 *    iowarrior_release
 */
static int iowarrior_release(struct inode *inode, struct file *file)
{
      struct iowarrior *dev;
      int retval = 0;

      dev = (struct iowarrior *)file->private_data;
      if (dev == NULL) {
            return -ENODEV;
      }

      dbg("%s - minor %d", __func__, dev->minor);

      /* lock our device */
      mutex_lock(&dev->mutex);

      if (dev->opened <= 0) {
            retval = -ENODEV; /* close called more than once */
            mutex_unlock(&dev->mutex);
      } else {
            dev->opened = 0;  /* we're closeing now */
            retval = 0;
            if (dev->present) {
                  /*
                     The device is still connected so we only shutdown
                     pending read-/write-ops.
                   */
                  usb_kill_urb(dev->int_in_urb);
                  wake_up_interruptible(&dev->read_wait);
                  wake_up_interruptible(&dev->write_wait);
                  mutex_unlock(&dev->mutex);
            } else {
                  /* The device was unplugged, cleanup resources */
                  mutex_unlock(&dev->mutex);
                  iowarrior_delete(dev);
            }
      }
      return retval;
}

static unsigned iowarrior_poll(struct file *file, poll_table * wait)
{
      struct iowarrior *dev = file->private_data;
      unsigned int mask = 0;

      if (!dev->present)
            return POLLERR | POLLHUP;

      poll_wait(file, &dev->read_wait, wait);
      poll_wait(file, &dev->write_wait, wait);

      if (!dev->present)
            return POLLERR | POLLHUP;

      if (read_index(dev) != -1)
            mask |= POLLIN | POLLRDNORM;

      if (atomic_read(&dev->write_busy) < MAX_WRITES_IN_FLIGHT)
            mask |= POLLOUT | POLLWRNORM;
      return mask;
}

/*
 * File operations needed when we register this driver.
 * This assumes that this driver NEEDS file operations,
 * of course, which means that the driver is expected
 * to have a node in the /dev directory. If the USB
 * device were for a network interface then the driver
 * would use "struct net_driver" instead, and a serial
 * device would use "struct tty_driver".
 */
static struct file_operations iowarrior_fops = {
      .owner = THIS_MODULE,
      .write = iowarrior_write,
      .read = iowarrior_read,
      .ioctl = iowarrior_ioctl,
      .open = iowarrior_open,
      .release = iowarrior_release,
      .poll = iowarrior_poll,
};

/*
 * usb class driver info in order to get a minor number from the usb core,
 * and to have the device registered with devfs and the driver core
 */
static struct usb_class_driver iowarrior_class = {
      .name = "iowarrior%d",
      .fops = &iowarrior_fops,
      .minor_base = IOWARRIOR_MINOR_BASE,
};

/*---------------------------------*/
/*  probe and disconnect functions */
/*---------------------------------*/
/**
 *    iowarrior_probe
 *
 *    Called by the usb core when a new device is connected that it thinks
 *    this driver might be interested in.
 */
static int iowarrior_probe(struct usb_interface *interface,
                     const struct usb_device_id *id)
{
      struct usb_device *udev = interface_to_usbdev(interface);
      struct iowarrior *dev = NULL;
      struct usb_host_interface *iface_desc;
      struct usb_endpoint_descriptor *endpoint;
      int i;
      int retval = -ENOMEM;

      /* allocate memory for our device state and intialize it */
      dev = kzalloc(sizeof(struct iowarrior), GFP_KERNEL);
      if (dev == NULL) {
            dev_err(&interface->dev, "Out of memory\n");
            return retval;
      }

      mutex_init(&dev->mutex);

      atomic_set(&dev->intr_idx, 0);
      atomic_set(&dev->read_idx, 0);
      spin_lock_init(&dev->intr_idx_lock);
      atomic_set(&dev->overflow_flag, 0);
      init_waitqueue_head(&dev->read_wait);
      atomic_set(&dev->write_busy, 0);
      init_waitqueue_head(&dev->write_wait);

      dev->udev = udev;
      dev->interface = interface;

      iface_desc = interface->cur_altsetting;
      dev->product_id = le16_to_cpu(udev->descriptor.idProduct);

      /* set up the endpoint information */
      for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
            endpoint = &iface_desc->endpoint[i].desc;

            if (usb_endpoint_is_int_in(endpoint))
                  dev->int_in_endpoint = endpoint;
            if (usb_endpoint_is_int_out(endpoint))
                  /* this one will match for the IOWarrior56 only */
                  dev->int_out_endpoint = endpoint;
      }
      /* we have to check the report_size often, so remember it in the endianess suitable for our machine */
      dev->report_size = le16_to_cpu(dev->int_in_endpoint->wMaxPacketSize);
      if ((dev->interface->cur_altsetting->desc.bInterfaceNumber == 0) &&
          (dev->product_id == USB_DEVICE_ID_CODEMERCS_IOW56))
            /* IOWarrior56 has wMaxPacketSize different from report size */
            dev->report_size = 7;

      /* create the urb and buffer for reading */
      dev->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
      if (!dev->int_in_urb) {
            dev_err(&interface->dev, "Couldn't allocate interrupt_in_urb\n");
            goto error;
      }
      dev->int_in_buffer = kmalloc(dev->report_size, GFP_KERNEL);
      if (!dev->int_in_buffer) {
            dev_err(&interface->dev, "Couldn't allocate int_in_buffer\n");
            goto error;
      }
      usb_fill_int_urb(dev->int_in_urb, dev->udev,
                   usb_rcvintpipe(dev->udev,
                              dev->int_in_endpoint->bEndpointAddress),
                   dev->int_in_buffer, dev->report_size,
                   iowarrior_callback, dev,
                   dev->int_in_endpoint->bInterval);
      /* create an internal buffer for interrupt data from the device */
      dev->read_queue =
          kmalloc(((dev->report_size + 1) * MAX_INTERRUPT_BUFFER),
                GFP_KERNEL);
      if (!dev->read_queue) {
            dev_err(&interface->dev, "Couldn't allocate read_queue\n");
            goto error;
      }
      /* Get the serial-number of the chip */
      memset(dev->chip_serial, 0x00, sizeof(dev->chip_serial));
      usb_string(udev, udev->descriptor.iSerialNumber, dev->chip_serial,
               sizeof(dev->chip_serial));
      if (strlen(dev->chip_serial) != 8)
            memset(dev->chip_serial, 0x00, sizeof(dev->chip_serial));

      /* Set the idle timeout to 0, if this is interface 0 */
      if (dev->interface->cur_altsetting->desc.bInterfaceNumber == 0) {
          usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                      0x0A,
                      USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0,
                      0, NULL, 0, USB_CTRL_SET_TIMEOUT);
      }
      /* allow device read and ioctl */
      dev->present = 1;

      /* we can register the device now, as it is ready */
      usb_set_intfdata(interface, dev);

      retval = usb_register_dev(interface, &iowarrior_class);
      if (retval) {
            /* something prevented us from registering this driver */
            dev_err(&interface->dev, "Not able to get a minor for this device.\n");
            usb_set_intfdata(interface, NULL);
            goto error;
      }

      dev->minor = interface->minor;

      /* let the user know what node this device is now attached to */
      dev_info(&interface->dev, "IOWarrior product=0x%x, serial=%s interface=%d "
             "now attached to iowarrior%d\n", dev->product_id, dev->chip_serial,
             iface_desc->desc.bInterfaceNumber, dev->minor - IOWARRIOR_MINOR_BASE);
      return retval;

error:
      iowarrior_delete(dev);
      return retval;
}

/**
 *    iowarrior_disconnect
 *
 *    Called by the usb core when the device is removed from the system.
 */
static void iowarrior_disconnect(struct usb_interface *interface)
{
      struct iowarrior *dev;
      int minor;

      dev = usb_get_intfdata(interface);
      mutex_lock(&iowarrior_open_disc_lock);
      usb_set_intfdata(interface, NULL);

      minor = dev->minor;

      /* give back our minor */
      usb_deregister_dev(interface, &iowarrior_class);

      mutex_lock(&dev->mutex);

      /* prevent device read, write and ioctl */
      dev->present = 0;

      mutex_unlock(&dev->mutex);
      mutex_unlock(&iowarrior_open_disc_lock);

      if (dev->opened) {
            /* There is a process that holds a filedescriptor to the device ,
               so we only shutdown read-/write-ops going on.
               Deleting the device is postponed until close() was called.
             */
            usb_kill_urb(dev->int_in_urb);
            wake_up_interruptible(&dev->read_wait);
            wake_up_interruptible(&dev->write_wait);
      } else {
            /* no process is using the device, cleanup now */
            iowarrior_delete(dev);
      }

      dev_info(&interface->dev, "I/O-Warror #%d now disconnected\n",
             minor - IOWARRIOR_MINOR_BASE);
}

/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver iowarrior_driver = {
      .name = "iowarrior",
      .probe = iowarrior_probe,
      .disconnect = iowarrior_disconnect,
      .id_table = iowarrior_ids,
};

static int __init iowarrior_init(void)
{
      return usb_register(&iowarrior_driver);
}

static void __exit iowarrior_exit(void)
{
      usb_deregister(&iowarrior_driver);
}

module_init(iowarrior_init);
module_exit(iowarrior_exit);

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