// SPDX-License-Identifier: GPL-2.0+
/*
 * copyright (C) 1999/2000 by Henning Zabel <henning@uni-paderborn.de>
 */


/*
 *      USB-Kernel Driver for the Mustek MDC800 Digital Camera
 *      (c) 1999/2000 Henning Zabel <henning@uni-paderborn.de>
 *
 *
 * The driver brings the USB functions of the MDC800 to Linux.
 * To use the Camera you must support the USB Protocol of the camera
 * to the Kernel Node.
 * The Driver uses a misc device Node. Create it with :
 * mknod /dev/mustek c 180 32
 *
 * The driver supports only one camera.
 * 
 * Fix: mdc800 used sleep_on and slept with io_lock held.
 * Converted sleep_on to waitqueues with schedule_timeout and made io_lock
 * a semaphore from a spinlock.
 * by Oliver Neukum <oliver@neukum.name>
 * (02/12/2001)
 * 
 * Identify version on module load.
 * (08/04/2001) gb
 *
 * version 0.7.5
 * Fixed potential SMP races with Spinlocks.
 * Thanks to Oliver Neukum <oliver@neukum.name> who 
 * noticed the race conditions.
 * (30/10/2000)
 *
 * Fixed: Setting urb->dev before submitting urb.
 * by Greg KH <greg@kroah.com>
 * (13/10/2000)
 *
 * version 0.7.3
 * bugfix : The mdc800->state field gets set to READY after the
 * disconnect function sets it to NOT_CONNECTED. This makes the
 * driver running like the camera is connected and causes some
 * hang ups.
 *
 * version 0.7.1
 * MOD_INC and MOD_DEC are changed in usb_probe to prevent load/unload
 * problems when compiled as Module.
 * (04/04/2000)
 *
 * The mdc800 driver gets assigned the USB Minor 32-47. The Registration
 * was updated to use these values.
 * (26/03/2000)
 *
 * The Init und Exit Module Function are updated.
 * (01/03/2000)
 *
 * version 0.7.0
 * Rewrite of the driver : The driver now uses URB's. The old stuff
 * has been removed.
 *
 * version 0.6.0
 * Rewrite of this driver: The Emulation of the rs232 protocoll
 * has been removed from the driver. A special executeCommand function
 * for this driver is included to gphoto.
 * The driver supports two kind of communication to bulk endpoints.
 * Either with the dev->bus->ops->bulk... or with callback function.
 * (09/11/1999)
 *
 * version 0.5.0:
 * first Version that gets a version number. Most of the needed
 * functions work.
 * (20/10/1999)
 */

#include <linux/sched/signal.h>
#include <linux/signal.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/wait.h>
#include <linux/mutex.h>

#include <linux/usb.h>
#include <linux/fs.h>

/*
 * Version Information
 */
#define DRIVER_VERSION "v0.7.5 (30/10/2000)"
#define DRIVER_AUTHOR "Henning Zabel <henning@uni-paderborn.de>"
#define DRIVER_DESC "USB Driver for Mustek MDC800 Digital Camera"

/* Vendor and Product Information */
#define MDC800_VENDOR_ID        0x055f
#define MDC800_PRODUCT_ID       0xa800

/* Timeouts (msec) */
#define TO_DOWNLOAD_GET_READY           1500
#define TO_DOWNLOAD_GET_BUSY            1500
#define TO_WRITE_GET_READY              1000
#define TO_DEFAULT_COMMAND              5000
#define TO_READ_FROM_IRQ                TO_DEFAULT_COMMAND
#define TO_GET_READY                    TO_DEFAULT_COMMAND

/* Minor Number of the device (create with mknod /dev/mustek c 180 32) */
#define MDC800_DEVICE_MINOR_BASE 32


/**************************************************************************
        Data and structs
***************************************************************************/


typedef enum {
        NOT_CONNECTED, READY, WORKING, DOWNLOAD
} mdc800_state;


/* Data for the driver */
struct mdc800_data
{
        struct usb_device *     dev;                    // Device Data
        mdc800_state            state;

        unsigned int            endpoint [4];

        struct urb *            irq_urb;
        wait_queue_head_t       irq_wait;
        int                     irq_woken;
        char*                   irq_urb_buffer;

        int                     camera_busy;          // is camera busy ?
        int                     camera_request_ready; // Status to synchronize with irq
        char                    camera_response [8];  // last Bytes send after busy

        struct urb *            write_urb;
        char*                   write_urb_buffer;
        wait_queue_head_t       write_wait;
        int                     written;


        struct urb *            download_urb;
        char*                   download_urb_buffer;
        wait_queue_head_t       download_wait;
        int                     downloaded;
        int                     download_left;          // Bytes left to download ?


        /* Device Data */
        char                    out [64];       // Answer Buffer
        int                     out_ptr;        // Index to the first not readen byte
        int                     out_count;      // Bytes in the buffer

        int                     open;           // Camera device open ?
        struct mutex            io_lock;        // IO -lock

        char                    in [8];         // Command Input Buffer
        int                     in_count;

        int                     pic_index;      // Cache for the Imagesize (-1 for nothing cached )
        int                     pic_len;
        int                     minor;
};


/* Specification of the Endpoints */
static struct usb_endpoint_descriptor mdc800_ed [4] =
{
        { 
                .bLength =              0,
                .bDescriptorType =      0,
                .bEndpointAddress =     0x01,
                .bmAttributes =         0x02,
                .wMaxPacketSize =       cpu_to_le16(8),
                .bInterval =            0,
                .bRefresh =             0,
                .bSynchAddress =        0,
        },
        {
                .bLength =              0,
                .bDescriptorType =      0,
                .bEndpointAddress =     0x82,
                .bmAttributes =         0x03,
                .wMaxPacketSize =       cpu_to_le16(8),
                .bInterval =            0,
                .bRefresh =             0,
                .bSynchAddress =        0,
        },
        {
                .bLength =              0,
                .bDescriptorType =      0,
                .bEndpointAddress =     0x03,
                .bmAttributes =         0x02,
                .wMaxPacketSize =       cpu_to_le16(64),
                .bInterval =            0,
                .bRefresh =             0,
                .bSynchAddress =        0,
        },
        {
                .bLength =              0,
                .bDescriptorType =      0,
                .bEndpointAddress =     0x84,
                .bmAttributes =         0x02,
                .wMaxPacketSize =       cpu_to_le16(64),
                .bInterval =            0,
                .bRefresh =             0,
                .bSynchAddress =        0,
        },
};

/* The Variable used by the driver */
static struct mdc800_data* mdc800;


/***************************************************************************
        The USB Part of the driver
****************************************************************************/

static int mdc800_endpoint_equals (struct usb_endpoint_descriptor *a,struct usb_endpoint_descriptor *b)
{
        return (
                   ( a->bEndpointAddress == b->bEndpointAddress )
                && ( a->bmAttributes     == b->bmAttributes     )
                && ( a->wMaxPacketSize   == b->wMaxPacketSize   )
        );
}


/*
 * Checks whether the camera responds busy
 */
static int mdc800_isBusy (char* ch)
{
        int i=0;
        while (i<8)
        {
                if (ch [i] != (char)0x99)
                        return 0;
                i++;
        }
        return 1;
}


/*
 * Checks whether the Camera is ready
 */
static int mdc800_isReady (char *ch)
{
        int i=0;
        while (i<8)
        {
                if (ch [i] != (char)0xbb)
                        return 0;
                i++;
        }
        return 1;
}



/*
 * USB IRQ Handler for InputLine
 */
static void mdc800_usb_irq (struct urb *urb)
{
        int data_received=0, wake_up;
        unsigned char* b=urb->transfer_buffer;
        struct mdc800_data* mdc800=urb->context;
        struct device *dev = &mdc800->dev->dev;
        int status = urb->status;

        if (status >= 0) {
                if (mdc800_isBusy (b))
                {
                        if (!mdc800->camera_busy)
                        {
                                mdc800->camera_busy=1;
                                dev_dbg(dev, "gets busy\n");
                        }
                }
                else
                {
                        if (mdc800->camera_busy && mdc800_isReady (b))
                        {
                                mdc800->camera_busy=0;
                                dev_dbg(dev, "gets ready\n");
                        }
                }
                if (!(mdc800_isBusy (b) || mdc800_isReady (b)))
                {
                        /* Store Data in camera_answer field */
                        dev_dbg(dev, "%i %i %i %i %i %i %i %i \n",b[0],b[1],b[2],b[3],b[4],b[5],b[6],b[7]);

                        memcpy (mdc800->camera_response,b,8);
                        data_received=1;
                }
        }
        wake_up= ( mdc800->camera_request_ready > 0 )
                &&
                (
                        ((mdc800->camera_request_ready == 1) && (!mdc800->camera_busy))
                ||
                        ((mdc800->camera_request_ready == 2) && data_received)
                ||
                        ((mdc800->camera_request_ready == 3) && (mdc800->camera_busy))
                ||
                        (status < 0)
                );

        if (wake_up)
        {
                mdc800->camera_request_ready=0;
                mdc800->irq_woken=1;
                wake_up (&mdc800->irq_wait);
        }
}


/*
 * Waits a while until the irq responds that camera is ready
 *
 *  mode : 0: Wait for camera gets ready
 *         1: Wait for receiving data
 *         2: Wait for camera gets busy
 *
 * msec: Time to wait
 */
static int mdc800_usb_waitForIRQ (int mode, int msec)
{
        mdc800->camera_request_ready=1+mode;

        wait_event_timeout(mdc800->irq_wait, mdc800->irq_woken,
                           msecs_to_jiffies(msec));
        mdc800->irq_woken = 0;

        if (mdc800->camera_request_ready>0)
        {
                mdc800->camera_request_ready=0;
                dev_err(&mdc800->dev->dev, "timeout waiting for camera.\n");
                return -1;
        }
        
        if (mdc800->state == NOT_CONNECTED)
        {
                printk(KERN_WARNING "mdc800: Camera gets disconnected "
                       "during waiting for irq.\n");
                mdc800->camera_request_ready=0;
                return -2;
        }
        
        return 0;
}


/*
 * The write_urb callback function
 */
static void mdc800_usb_write_notify (struct urb *urb)
{
        struct mdc800_data* mdc800=urb->context;
        int status = urb->status;

        if (status != 0)
                dev_err(&mdc800->dev->dev,
                        "writing command fails (status=%i)\n", status);
        else
                mdc800->state=READY;
        mdc800->written = 1;
        wake_up (&mdc800->write_wait);
}


/*
 * The download_urb callback function
 */
static void mdc800_usb_download_notify (struct urb *urb)
{
        struct mdc800_data* mdc800=urb->context;
        int status = urb->status;

        if (status == 0) {
                /* Fill output buffer with these data */
                memcpy (mdc800->out,  urb->transfer_buffer, 64);
                mdc800->out_count=64;
                mdc800->out_ptr=0;
                mdc800->download_left-=64;
                if (mdc800->download_left == 0)
                {
                        mdc800->state=READY;
                }
        } else {
                dev_err(&mdc800->dev->dev,
                        "request bytes fails (status:%i)\n", status);
        }
        mdc800->downloaded = 1;
        wake_up (&mdc800->download_wait);
}


/***************************************************************************
        Probing for the Camera
 ***************************************************************************/

static struct usb_driver mdc800_usb_driver;
static const struct file_operations mdc800_device_ops;
static struct usb_class_driver mdc800_class = {
        .name =         "mdc800%d",
        .fops =         &mdc800_device_ops,
        .minor_base =   MDC800_DEVICE_MINOR_BASE,
};


/*
 * Callback to search the Mustek MDC800 on the USB Bus
 */
static int mdc800_usb_probe (struct usb_interface *intf,
                               const struct usb_device_id *id)
{
        int i,j;
        struct usb_host_interface *intf_desc;
        struct usb_device *dev = interface_to_usbdev (intf);
        int irq_interval=0;
        int retval;

        dev_dbg(&intf->dev, "(%s) called.\n", __func__);


        if (mdc800->dev != NULL)
        {
                dev_warn(&intf->dev, "only one Mustek MDC800 is supported.\n");
                return -ENODEV;
        }

        if (dev->descriptor.bNumConfigurations != 1)
        {
                dev_err(&intf->dev,
                        "probe fails -> wrong Number of Configuration\n");
                return -ENODEV;
        }
        intf_desc = intf->cur_altsetting;

        if (
                        ( intf_desc->desc.bInterfaceClass != 0xff )
                ||      ( intf_desc->desc.bInterfaceSubClass != 0 )
                || ( intf_desc->desc.bInterfaceProtocol != 0 )
                || ( intf_desc->desc.bNumEndpoints != 4)
        )
        {
                dev_err(&intf->dev, "probe fails -> wrong Interface\n");
                return -ENODEV;
        }

        /* Check the Endpoints */
        for (i=0; i<4; i++)
        {
                mdc800->endpoint[i]=-1;
                for (j=0; j<4; j++)
                {
                        if (mdc800_endpoint_equals (&intf_desc->endpoint [j].desc,&mdc800_ed [i]))
                        {
                                mdc800->endpoint[i]=intf_desc->endpoint [j].desc.bEndpointAddress ;
                                if (i==1)
                                {
                                        irq_interval=intf_desc->endpoint [j].desc.bInterval;
                                }
                        }
                }
                if (mdc800->endpoint[i] == -1)
                {
                        dev_err(&intf->dev, "probe fails -> Wrong Endpoints.\n");
                        return -ENODEV;
                }
        }


        dev_info(&intf->dev, "Found Mustek MDC800 on USB.\n");

        mutex_lock(&mdc800->io_lock);

        retval = usb_register_dev(intf, &mdc800_class);
        if (retval) {
                dev_err(&intf->dev, "Not able to get a minor for this device.\n");
                mutex_unlock(&mdc800->io_lock);
                return -ENODEV;
        }

        mdc800->dev=dev;
        mdc800->open=0;

        /* Setup URB Structs */
        usb_fill_int_urb (
                mdc800->irq_urb,
                mdc800->dev,
                usb_rcvintpipe (mdc800->dev,mdc800->endpoint [1]),
                mdc800->irq_urb_buffer,
                8,
                mdc800_usb_irq,
                mdc800,
                irq_interval
        );

        usb_fill_bulk_urb (
                mdc800->write_urb,
                mdc800->dev,
                usb_sndbulkpipe (mdc800->dev, mdc800->endpoint[0]),
                mdc800->write_urb_buffer,
                8,
                mdc800_usb_write_notify,
                mdc800
        );

        usb_fill_bulk_urb (
                mdc800->download_urb,
                mdc800->dev,
                usb_rcvbulkpipe (mdc800->dev, mdc800->endpoint [3]),
                mdc800->download_urb_buffer,
                64,
                mdc800_usb_download_notify,
                mdc800
        );

        mdc800->state=READY;

        mutex_unlock(&mdc800->io_lock);
        
        usb_set_intfdata(intf, mdc800);
        return 0;
}


/*
 * Disconnect USB device (maybe the MDC800)
 */
static void mdc800_usb_disconnect (struct usb_interface *intf)
{
        struct mdc800_data* mdc800 = usb_get_intfdata(intf);

        dev_dbg(&intf->dev, "(%s) called\n", __func__);

        if (mdc800) {
                if (mdc800->state == NOT_CONNECTED)
                        return;

                usb_deregister_dev(intf, &mdc800_class);

                /* must be under lock to make sure no URB
                   is submitted after usb_kill_urb() */
                mutex_lock(&mdc800->io_lock);
                mdc800->state=NOT_CONNECTED;

                usb_kill_urb(mdc800->irq_urb);
                usb_kill_urb(mdc800->write_urb);
                usb_kill_urb(mdc800->download_urb);
                mutex_unlock(&mdc800->io_lock);

                mdc800->dev = NULL;
                usb_set_intfdata(intf, NULL);
        }
        dev_info(&intf->dev, "Mustek MDC800 disconnected from USB.\n");
}


/***************************************************************************
        The Misc device Part (file_operations)
****************************************************************************/

/*
 * This Function calc the Answersize for a command.
 */
static int mdc800_getAnswerSize (char command)
{
        switch ((unsigned char) command)
        {
                case 0x2a:
                case 0x49:
                case 0x51:
                case 0x0d:
                case 0x20:
                case 0x07:
                case 0x01:
                case 0x25:
                case 0x00:
                        return 8;

                case 0x05:
                case 0x3e:
                        return mdc800->pic_len;

                case 0x09:
                        return 4096;

                default:
                        return 0;
        }
}


/*
 * Init the device: (1) alloc mem (2) Increase MOD Count ..
 */
static int mdc800_device_open (struct inode* inode, struct file *file)
{
        int retval=0;
        int errn=0;

        mutex_lock(&mdc800->io_lock);
        
        if (mdc800->state == NOT_CONNECTED)
        {
                errn=-EBUSY;
                goto error_out;
        }
        if (mdc800->open)
        {
                errn=-EBUSY;
                goto error_out;
        }

        mdc800->in_count=0;
        mdc800->out_count=0;
        mdc800->out_ptr=0;
        mdc800->pic_index=0;
        mdc800->pic_len=-1;
        mdc800->download_left=0;

        mdc800->camera_busy=0;
        mdc800->camera_request_ready=0;

        mdc800->irq_urb->dev = mdc800->dev;
        retval = usb_submit_urb (mdc800->irq_urb, GFP_KERNEL);
        if (retval) {
                dev_err(&mdc800->dev->dev,
                        "request USB irq fails (submit_retval=%i).\n", retval);
                errn = -EIO;
                goto error_out;
        }

        mdc800->open=1;
        dev_dbg(&mdc800->dev->dev, "Mustek MDC800 device opened.\n");

error_out:
        mutex_unlock(&mdc800->io_lock);
        return errn;
}


/*
 * Close the Camera and release Memory
 */
static int mdc800_device_release (struct inode* inode, struct file *file)
{
        int retval=0;

        mutex_lock(&mdc800->io_lock);
        if (mdc800->open && (mdc800->state != NOT_CONNECTED))
        {
                usb_kill_urb(mdc800->irq_urb);
                usb_kill_urb(mdc800->write_urb);
                usb_kill_urb(mdc800->download_urb);
                mdc800->open=0;
        }
        else
        {
                retval=-EIO;
        }

        mutex_unlock(&mdc800->io_lock);
        return retval;
}


/*
 * The Device read callback Function
 */
static ssize_t mdc800_device_read (struct file *file, char __user *buf, size_t len, loff_t *pos)
{
        size_t left=len, sts=len; /* single transfer size */
        char __user *ptr = buf;
        int retval;

        mutex_lock(&mdc800->io_lock);
        if (mdc800->state == NOT_CONNECTED)
        {
                mutex_unlock(&mdc800->io_lock);
                return -EBUSY;
        }
        if (mdc800->state == WORKING)
        {
                printk(KERN_WARNING "mdc800: Illegal State \"working\""
                       "reached during read ?!\n");
                mutex_unlock(&mdc800->io_lock);
                return -EBUSY;
        }
        if (!mdc800->open)
        {
                mutex_unlock(&mdc800->io_lock);
                return -EBUSY;
        }

        while (left)
        {
                if (signal_pending (current)) 
                {
                        mutex_unlock(&mdc800->io_lock);
                        return len == left ? -EINTR : len-left;
                }

                sts=left > (mdc800->out_count-mdc800->out_ptr)?mdc800->out_count-mdc800->out_ptr:left;

                if (sts <= 0)
                {
                        /* Too less Data in buffer */
                        if (mdc800->state == DOWNLOAD)
                        {
                                mdc800->out_count=0;
                                mdc800->out_ptr=0;

                                /* Download -> Request new bytes */
                                mdc800->download_urb->dev = mdc800->dev;
                                retval = usb_submit_urb (mdc800->download_urb, GFP_KERNEL);
                                if (retval) {
                                        dev_err(&mdc800->dev->dev,
                                                "Can't submit download urb "
                                                "(retval=%i)\n", retval);
                                        mutex_unlock(&mdc800->io_lock);
                                        return len-left;
                                }
                                retval = wait_event_timeout(mdc800->download_wait,
                                     mdc800->downloaded,
                                     msecs_to_jiffies(TO_DOWNLOAD_GET_READY));
                                if (!retval)
                                        usb_kill_urb(mdc800->download_urb);
                                mdc800->downloaded = 0;
                                if (mdc800->download_urb->status != 0)
                                {
                                        dev_err(&mdc800->dev->dev,
                                                "request download-bytes fails "
                                                "(status=%i)\n",
                                                mdc800->download_urb->status);
                                        mutex_unlock(&mdc800->io_lock);
                                        return len-left;
                                }
                        }
                        else
                        {
                                /* No more bytes -> that's an error*/
                                mutex_unlock(&mdc800->io_lock);
                                return -EIO;
                        }
                }
                else
                {
                        /* Copy Bytes */
                        if (copy_to_user(ptr, &mdc800->out [mdc800->out_ptr],
                                                sts)) {
                                mutex_unlock(&mdc800->io_lock);
                                return -EFAULT;
                        }
                        ptr+=sts;
                        left-=sts;
                        mdc800->out_ptr+=sts;
                }
        }

        mutex_unlock(&mdc800->io_lock);
        return len-left;
}


/*
 * The Device write callback Function
 * If a 8Byte Command is received, it will be send to the camera.
 * After this the driver initiates the request for the answer or
 * just waits until the camera becomes ready.
 */
static ssize_t mdc800_device_write (struct file *file, const char __user *buf, size_t len, loff_t *pos)
{
        size_t i=0;
        int retval;

        mutex_lock(&mdc800->io_lock);
        if (mdc800->state != READY)
        {
                mutex_unlock(&mdc800->io_lock);
                return -EBUSY;
        }
        if (!mdc800->open )
        {
                mutex_unlock(&mdc800->io_lock);
                return -EBUSY;
        }

        while (i<len)
        {
                unsigned char c;
                if (signal_pending (current)) 
                {
                        mutex_unlock(&mdc800->io_lock);
                        return -EINTR;
                }
                
                if(get_user(c, buf+i))
                {
                        mutex_unlock(&mdc800->io_lock);
                        return -EFAULT;
                }

                /* check for command start */
                if (c == 0x55)
                {
                        mdc800->in_count=0;
                        mdc800->out_count=0;
                        mdc800->out_ptr=0;
                        mdc800->download_left=0;
                }

                /* save command byte */
                if (mdc800->in_count < 8)
                {
                        mdc800->in[mdc800->in_count] = c;
                        mdc800->in_count++;
                }
                else
                {
                        mutex_unlock(&mdc800->io_lock);
                        return -EIO;
                }

                /* Command Buffer full ? -> send it to camera */
                if (mdc800->in_count == 8)
                {
                        int answersize;

                        if (mdc800_usb_waitForIRQ (0,TO_GET_READY))
                        {
                                dev_err(&mdc800->dev->dev,
                                        "Camera didn't get ready.\n");
                                mutex_unlock(&mdc800->io_lock);
                                return -EIO;
                        }

                        answersize=mdc800_getAnswerSize (mdc800->in[1]);

                        mdc800->state=WORKING;
                        memcpy (mdc800->write_urb->transfer_buffer, mdc800->in,8);
                        mdc800->write_urb->dev = mdc800->dev;
                        retval = usb_submit_urb (mdc800->write_urb, GFP_KERNEL);
                        if (retval) {
                                dev_err(&mdc800->dev->dev,
                                        "submitting write urb fails "
                                        "(retval=%i)\n", retval);
                                mutex_unlock(&mdc800->io_lock);
                                return -EIO;
                        }
                        wait_event_timeout(mdc800->write_wait, mdc800->written,
                                        msecs_to_jiffies(TO_WRITE_GET_READY));
                        mdc800->written = 0;
                        if (mdc800->state == WORKING)
                        {
                                usb_kill_urb(mdc800->write_urb);
                                mutex_unlock(&mdc800->io_lock);
                                return -EIO;
                        }

                        switch ((unsigned char) mdc800->in[1])
                        {
                                case 0x05: /* Download Image */
                                case 0x3e: /* Take shot in Fine Mode (WCam Mode) */
                                        if (mdc800->pic_len < 0)
                                        {
                                                dev_err(&mdc800->dev->dev,
                                                        "call 0x07 before "
                                                        "0x05,0x3e\n");
                                                mdc800->state=READY;
                                                mutex_unlock(&mdc800->io_lock);
                                                return -EIO;
                                        }
                                        mdc800->pic_len=-1;
                                        fallthrough;

                                case 0x09: /* Download Thumbnail */
                                        mdc800->download_left=answersize+64;
                                        mdc800->state=DOWNLOAD;
                                        mdc800_usb_waitForIRQ (0,TO_DOWNLOAD_GET_BUSY);
                                        break;


                                default:
                                        if (answersize)
                                        {

                                                if (mdc800_usb_waitForIRQ (1,TO_READ_FROM_IRQ))
                                                {
                                                        dev_err(&mdc800->dev->dev, "requesting answer from irq fails\n");
                                                        mutex_unlock(&mdc800->io_lock);
                                                        return -EIO;
                                                }

                                                /* Write dummy data, (this is ugly but part of the USB Protocol */
                                                /* if you use endpoint 1 as bulk and not as irq) */
                                                memcpy (mdc800->out, mdc800->camera_response,8);

                                                /* This is the interpreted answer */
                                                memcpy (&mdc800->out[8], mdc800->camera_response,8);

                                                mdc800->out_ptr=0;
                                                mdc800->out_count=16;

                                                /* Cache the Imagesize, if command was getImageSize */
                                                if (mdc800->in [1] == (char) 0x07)
                                                {
                                                        mdc800->pic_len=(int) 65536*(unsigned char) mdc800->camera_response[0]+256*(unsigned char) mdc800->camera_response[1]+(unsigned char) mdc800->camera_response[2];

                                                        dev_dbg(&mdc800->dev->dev, "cached imagesize = %i\n", mdc800->pic_len);
                                                }

                                        }
                                        else
                                        {
                                                if (mdc800_usb_waitForIRQ (0,TO_DEFAULT_COMMAND))
                                                {
                                                        dev_err(&mdc800->dev->dev, "Command Timeout.\n");
                                                        mutex_unlock(&mdc800->io_lock);
                                                        return -EIO;
                                                }
                                        }
                                        mdc800->state=READY;
                                        break;
                        }
                }
                i++;
        }
        mutex_unlock(&mdc800->io_lock);
        return i;
}


/***************************************************************************
        Init and Cleanup this driver (Structs and types)
****************************************************************************/

/* File Operations of this drivers */
static const struct file_operations mdc800_device_ops =
{
        .owner =        THIS_MODULE,
        .read =         mdc800_device_read,
        .write =        mdc800_device_write,
        .open =         mdc800_device_open,
        .release =      mdc800_device_release,
        .llseek =       noop_llseek,
};



static const struct usb_device_id mdc800_table[] = {
        { USB_DEVICE(MDC800_VENDOR_ID, MDC800_PRODUCT_ID) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, mdc800_table);
/*
 * USB Driver Struct for this device
 */
static struct usb_driver mdc800_usb_driver =
{
        .name =         "mdc800",
        .probe =        mdc800_usb_probe,
        .disconnect =   mdc800_usb_disconnect,
        .id_table =     mdc800_table
};



/************************************************************************
        Init and Cleanup this driver (Main Functions)
*************************************************************************/

static int __init usb_mdc800_init (void)
{
        int retval = -ENODEV;
        /* Allocate Memory */
        mdc800=kzalloc_obj(struct mdc800_data);
        if (!mdc800)
                goto cleanup_on_fail;

        mdc800->dev = NULL;
        mdc800->state=NOT_CONNECTED;
        mutex_init (&mdc800->io_lock);

        init_waitqueue_head (&mdc800->irq_wait);
        init_waitqueue_head (&mdc800->write_wait);
        init_waitqueue_head (&mdc800->download_wait);

        mdc800->irq_woken = 0;
        mdc800->downloaded = 0;
        mdc800->written = 0;

        mdc800->irq_urb_buffer=kmalloc (8, GFP_KERNEL);
        if (!mdc800->irq_urb_buffer)
                goto cleanup_on_fail;
        mdc800->write_urb_buffer=kmalloc (8, GFP_KERNEL);
        if (!mdc800->write_urb_buffer)
                goto cleanup_on_fail;
        mdc800->download_urb_buffer=kmalloc (64, GFP_KERNEL);
        if (!mdc800->download_urb_buffer)
                goto cleanup_on_fail;

        mdc800->irq_urb=usb_alloc_urb (0, GFP_KERNEL);
        if (!mdc800->irq_urb)
                goto cleanup_on_fail;
        mdc800->download_urb=usb_alloc_urb (0, GFP_KERNEL);
        if (!mdc800->download_urb)
                goto cleanup_on_fail;
        mdc800->write_urb=usb_alloc_urb (0, GFP_KERNEL);
        if (!mdc800->write_urb)
                goto cleanup_on_fail;

        /* Register the driver */
        retval = usb_register(&mdc800_usb_driver);
        if (retval)
                goto cleanup_on_fail;

        printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
               DRIVER_DESC "\n");

        return 0;

        /* Clean driver up, when something fails */

cleanup_on_fail:

        if (mdc800 != NULL)
        {
                printk(KERN_ERR "mdc800: can't alloc memory!\n");

                kfree(mdc800->download_urb_buffer);
                kfree(mdc800->write_urb_buffer);
                kfree(mdc800->irq_urb_buffer);

                usb_free_urb(mdc800->write_urb);
                usb_free_urb(mdc800->download_urb);
                usb_free_urb(mdc800->irq_urb);

                kfree (mdc800);
        }
        mdc800 = NULL;
        return retval;
}


static void __exit usb_mdc800_cleanup (void)
{
        usb_deregister (&mdc800_usb_driver);

        usb_free_urb (mdc800->irq_urb);
        usb_free_urb (mdc800->download_urb);
        usb_free_urb (mdc800->write_urb);

        kfree (mdc800->irq_urb_buffer);
        kfree (mdc800->write_urb_buffer);
        kfree (mdc800->download_urb_buffer);

        kfree (mdc800);
        mdc800 = NULL;
}

module_init (usb_mdc800_init);
module_exit (usb_mdc800_cleanup);

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