/* Linux driver for Philips webcam
   USB and Video4Linux interface part.
   (C) 1999-2003 Nemosoft Unv.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*/

/*  
   This code forms the interface between the USB layers and the Philips
   specific stuff. Some adanved stuff of the driver falls under an
   NDA, signed between me and Philips B.V., Eindhoven, the Netherlands, and
   is thus not distributed in source form. The binary pwcx.o module 
   contains the code that falls under the NDA.
   
   In case you're wondering: 'pwc' stands for "Philips WebCam", but 
   I really didn't want to type 'philips_web_cam' every time (I'm lazy as
   any Linux kernel hacker, but I don't like uncomprehensible abbreviations
   without explanation).
   
   Oh yes, convention: to disctinguish between all the various pointers to
   device-structures, I use these names for the pointer variables:
   udev: struct usb_device *
   vdev: struct video_device *
   pdev: struct pwc_devive *
*/

/* Contributors:
   - Alvarado: adding whitebalance code
   - Alistar Moire: QuickCam 3000 Pro device/product ID
   - Tony Hoyle: Creative Labs Webcam 5 device/product ID
   - Mark Burazin: solving hang in VIDIOCSYNC when camera gets unplugged
   - Jk Fang: Sotec Afina Eye ID
   - Xavier Roche: QuickCam Pro 4000 ID
   - Jens Knudsen: QuickCam Zoom ID
   - J. Debert: QuickCam for Notebooks ID
*/

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/wrapper.h>
#include <asm/io.h>

#include "pwc.h"
#include "pwc-ioctl.h"
#include "pwc-uncompress.h"

/* Function prototypes and driver templates */

/* hotplug device table support */
static struct usb_device_id pwc_device_table [] = {
        { USB_DEVICE(0x0471, 0x0302) }, /* Philips models */
        { USB_DEVICE(0x0471, 0x0303) },
        { USB_DEVICE(0x0471, 0x0304) },
        { USB_DEVICE(0x0471, 0x0307) },
        { USB_DEVICE(0x0471, 0x0308) },
        { USB_DEVICE(0x0471, 0x030C) },
        { USB_DEVICE(0x0471, 0x0310) },
        { USB_DEVICE(0x0471, 0x0311) },
        { USB_DEVICE(0x0471, 0x0312) },
        { USB_DEVICE(0x0471, 0x0313) }, /* the 'new' 720K */
        { USB_DEVICE(0x069A, 0x0001) }, /* Askey */
        { USB_DEVICE(0x046D, 0x08B0) }, /* Logitech QuickCam Pro 3000 */
        { USB_DEVICE(0x046D, 0x08B1) }, /* Logitech QuickCam Notebook Pro */
        { USB_DEVICE(0x046D, 0x08B2) }, /* Logitech QuickCam Pro 4000 */
        { USB_DEVICE(0x046D, 0x08B3) }, /* Logitech QuickCam Zoom */
        { USB_DEVICE(0x046D, 0x08B4) }, /* Logitech (reserved) */
        { USB_DEVICE(0x046D, 0x08B5) }, /* Logitech (reserved) */
        { USB_DEVICE(0x046D, 0x08B6) }, /* Logitech (reserved) */
        { USB_DEVICE(0x046D, 0x08B7) }, /* Logitech (reserved) */
        { USB_DEVICE(0x046D, 0x08B8) }, /* Logitech (reserved) */
        { USB_DEVICE(0x055D, 0x9000) }, /* Samsung */
        { USB_DEVICE(0x055D, 0x9001) },
        { USB_DEVICE(0x041E, 0x400C) }, /* Creative Webcam 5 */
        { USB_DEVICE(0x041E, 0x4011) }, /* Creative Webcam Pro Ex */
        { USB_DEVICE(0x04CC, 0x8116) }, /* Afina Eye */
        { USB_DEVICE(0x0d81, 0x1910) }, /* Visionite */
        { USB_DEVICE(0x0d81, 0x1900) },
        { }
};
MODULE_DEVICE_TABLE(usb, pwc_device_table);

static void *usb_pwc_probe(struct usb_device *udev, unsigned int ifnum, const struct usb_device_id *id);
static void usb_pwc_disconnect(struct usb_device *udev, void *ptr);

static struct usb_driver pwc_driver =
{
        name:                   "Philips webcam",       /* name */
        id_table:               pwc_device_table,
        probe:                  usb_pwc_probe,          /* probe() */
        disconnect:             usb_pwc_disconnect,     /* disconnect() */
};

#define MAX_DEV_HINTS   20
#define MAX_ISOC_ERRORS 20

static int default_size = PSZ_QCIF;
static int default_fps = 10;
static int default_fbufs = 3;   /* Default number of frame buffers */
static int default_mbufs = 2;   /* Default number of mmap() buffers */
       int pwc_trace = TRACE_MODULE | TRACE_FLOW | TRACE_PWCX;
static int power_save = 0;
static int led_on = 100, led_off = 0; /* defaults to LED that is on while in use */
       int pwc_preferred_compression = 2; /* 0..3 = uncompressed..high */
static struct {
        int type;
        char serial_number[30];
        int device_node;
        struct pwc_device *pdev;
} device_hint[MAX_DEV_HINTS];

/***/

static int  pwc_video_open(struct video_device *vdev, int mode);
static void pwc_video_close(struct video_device *vdev);
static long pwc_video_read(struct video_device *vdev, char *buf, unsigned long count, int noblock);
static long pwc_video_write(struct video_device *vdev, const char *buf, unsigned long count, int noblock);
static unsigned int pwc_video_poll(struct video_device *vdev, struct file *file, poll_table *wait);
static int  pwc_video_ioctl(struct video_device *vdev, unsigned int cmd, void *arg);
static int  pwc_video_mmap(struct video_device *vdev, const char *adr, unsigned long size);

static struct video_device pwc_template = {
        owner:          THIS_MODULE,
        name:           "Philips Webcam",       /* Filled in later */
        type:           VID_TYPE_CAPTURE,
        hardware:       VID_HARDWARE_PWC,
        open:           pwc_video_open,
        close:          pwc_video_close,
        read:           pwc_video_read,
        write:          pwc_video_write,
        poll:           pwc_video_poll,
        ioctl:          pwc_video_ioctl,
        mmap:           pwc_video_mmap,
        initialize:     NULL,                   /* initialize */
        minor:          0                       /* minor */
};

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

/* Okay, this is some magic that I worked out and the reasoning behind it...

   The biggest problem with any USB device is of course: "what to do 
   when the user unplugs the device while it is in use by an application?"
   We have several options:
   1) Curse them with the 7 plagues when they do (requires divine intervention)
   2) Tell them not to (won't work: they'll do it anyway)
   3) Oops the kernel (this will have a negative effect on a user's uptime)
   4) Do something sensible.
   
   Of course, we go for option 4.

   It happens that this device will be linked to two times, once from
   usb_device and once from the video_device in their respective 'private'
   pointers. This is done when the device is probed() and all initialization
   succeeded. The pwc_device struct links back to both structures.

   When a device is unplugged while in use it will be removed from the 
   list of known USB devices; I also de-register it as a V4L device, but 
   unfortunately I can't free the memory since the struct is still in use
   by the file descriptor. This free-ing is then deferend until the first
   opportunity. Crude, but it works.
   
   A small 'advantage' is that if a user unplugs the cam and plugs it back
   in, it should get assigned the same video device minor, but unfortunately
   it's non-trivial to re-link the cam back to the video device... (that 
   would surely be magic! :))
*/

/***************************************************************************/
/* Private functions */

/* Here we want the physical address of the memory.
 * This is used when initializing the contents of the area.
 */
static inline unsigned long kvirt_to_pa(unsigned long adr) 
{
        unsigned long kva, ret;

        kva = (unsigned long) page_address(vmalloc_to_page((void *)adr));
        kva |= adr & (PAGE_SIZE-1); /* restore the offset */
        ret = __pa(kva);
        return ret;
}

static void * rvmalloc(unsigned long size)
{
        void * mem;
        unsigned long adr;

        size=PAGE_ALIGN(size);
        mem=vmalloc_32(size);
        if (mem) 
        {
                memset(mem, 0, size); /* Clear the ram out, no junk to the user */
                adr=(unsigned long) mem;
                while (size > 0) 
                {
                        mem_map_reserve(vmalloc_to_page((void *)adr));
                        adr+=PAGE_SIZE;
                        size-=PAGE_SIZE;
                }
        }
        return mem;
}

static void rvfree(void * mem, unsigned long size)
{
        unsigned long adr;

        if (mem) 
        {
                adr=(unsigned long) mem;
                while ((long) size > 0) 
                {
                        mem_map_unreserve(vmalloc_to_page((void *)adr));
                        adr+=PAGE_SIZE;
                        size-=PAGE_SIZE;
                }
                vfree(mem);
        }
}




static int pwc_allocate_buffers(struct pwc_device *pdev)
{
        int i;
        void *kbuf;

        Trace(TRACE_MEMORY, ">> pwc_allocate_buffers(pdev = 0x%p)\n", pdev);

        if (pdev == NULL)
                return -ENXIO;
                
#ifdef PWC_MAGIC
        if (pdev->magic != PWC_MAGIC) {
                Err("allocate_buffers(): magic failed.\n");
                return -ENXIO;
        }
#endif  
        /* Allocate Isochronuous pipe buffers */
        for (i = 0; i < MAX_ISO_BUFS; i++) {
                if (pdev->sbuf[i].data == NULL) {
                        kbuf = kmalloc(ISO_BUFFER_SIZE, GFP_KERNEL);
                        if (kbuf == NULL) {
                                Err("Failed to allocate iso buffer %d.\n", i);
                                return -ENOMEM;
                        }
                        Trace(TRACE_MEMORY, "Allocated iso buffer at %p.\n", kbuf);
                        pdev->sbuf[i].data = kbuf;
                        memset(kbuf, 0, ISO_BUFFER_SIZE);
                }
        }

        /* Allocate frame buffer structure */
        if (pdev->fbuf == NULL) {
                kbuf = kmalloc(default_fbufs * sizeof(struct pwc_frame_buf), GFP_KERNEL);
                if (kbuf == NULL) {
                        Err("Failed to allocate frame buffer structure.\n");
                        return -ENOMEM;
                }
                Trace(TRACE_MEMORY, "Allocated frame buffer structure at %p.\n", kbuf);
                pdev->fbuf = kbuf;
                memset(kbuf, 0, default_fbufs * sizeof(struct pwc_frame_buf));
        }
        /* create frame buffers, and make circular ring */
        for (i = 0; i < default_fbufs; i++) {
                if (pdev->fbuf[i].data == NULL) {
                        kbuf = vmalloc(PWC_FRAME_SIZE); /* need vmalloc since frame buffer > 128K */
                        if (kbuf == NULL) {
                                Err("Failed to allocate frame buffer %d.\n", i);
                                return -ENOMEM;
                        }
                        Trace(TRACE_MEMORY, "Allocated frame buffer %d at %p.\n", i, kbuf);
                        pdev->fbuf[i].data = kbuf;
                        memset(kbuf, 128, PWC_FRAME_SIZE);
                }
        }
        
        /* Allocate decompressor table space */
        kbuf = NULL;
        if (pdev->decompressor != NULL) {
                kbuf = kmalloc(pdev->decompressor->table_size, GFP_KERNEL);
                if (kbuf == NULL) {
                        Err("Failed to allocate decompress table.\n");
                        return -ENOMEM;
                }
                Trace(TRACE_MEMORY, "Allocated decompress table %p.\n", kbuf);
        }
        pdev->decompress_data = kbuf;
        
        /* Allocate image buffer; double buffer for mmap() */
        kbuf = rvmalloc(default_mbufs * pdev->len_per_image);
        if (kbuf == NULL) {
                Err("Failed to allocate image buffer(s).\n");
                return -ENOMEM;
        }
        Trace(TRACE_MEMORY, "Allocated image buffer at %p.\n", kbuf);
        pdev->image_data = kbuf;
        for (i = 0; i < default_mbufs; i++)
                pdev->image_ptr[i] = kbuf + i * pdev->len_per_image;
        for (; i < MAX_IMAGES; i++)
                pdev->image_ptr[i] = NULL;

        kbuf = NULL;
          
        Trace(TRACE_MEMORY, "<< pwc_allocate_buffers()\n");
        return 0;
}

static void pwc_free_buffers(struct pwc_device *pdev)
{
        int i;

        Trace(TRACE_MEMORY, "Entering free_buffers(%p).\n", pdev);

        if (pdev == NULL)
                return;
#ifdef PWC_MAGIC
        if (pdev->magic != PWC_MAGIC) {
                Err("free_buffers(): magic failed.\n");
                return;
        }
#endif  

        /* Release Iso-pipe buffers */
        for (i = 0; i < MAX_ISO_BUFS; i++)
                if (pdev->sbuf[i].data != NULL) {
                        Trace(TRACE_MEMORY, "Freeing ISO buffer at %p.\n", pdev->sbuf[i].data);
                        kfree(pdev->sbuf[i].data);
                        pdev->sbuf[i].data = NULL;
                }

        /* The same for frame buffers */
        if (pdev->fbuf != NULL) {
                for (i = 0; i < default_fbufs; i++) {
                        if (pdev->fbuf[i].data != NULL) {
                                Trace(TRACE_MEMORY, "Freeing frame buffer %d at %p.\n", i, pdev->fbuf[i].data);
                                vfree(pdev->fbuf[i].data);
                                pdev->fbuf[i].data = NULL;
                        }
                }
                kfree(pdev->fbuf);
                pdev->fbuf = NULL;
        }

        /* Intermediate decompression buffer & tables */
        if (pdev->decompress_data != NULL) {
                Trace(TRACE_MEMORY, "Freeing decompression buffer at %p.\n", pdev->decompress_data);
                kfree(pdev->decompress_data);
                pdev->decompress_data = NULL;
        }
        pdev->decompressor = NULL;

        /* Release image buffers */
        if (pdev->image_data != NULL) {
                Trace(TRACE_MEMORY, "Freeing image buffer at %p.\n", pdev->image_data);
                rvfree(pdev->image_data, default_mbufs * pdev->len_per_image);
        }
        pdev->image_data = NULL;
        
        Trace(TRACE_MEMORY, "Leaving free_buffers().\n");
}

/* The frame & image buffer mess. 

   Yes, this is a mess. Well, it used to be simple, but alas...  In this
   module, 3 buffers schemes are used to get the data from the USB bus to
   the user program. The first scheme involves the ISO buffers (called thus
   since they transport ISO data from the USB controller), and not really
   interesting. Suffices to say the data from this buffer is quickly 
   gathered in an interrupt handler (pwc_isoc_handler) and placed into the
   frame buffer.

   The frame buffer is the second scheme, and is the central element here.
   It collects the data from a single frame from the camera (hence, the
   name). Frames are delimited by the USB camera with a short USB packet,
   so that's easy to detect. The frame buffers form a list that is filled
   by the camera+USB controller and drained by the user process through
   either read() or mmap().

   The image buffer is the third scheme, in which frames are decompressed
   and converted into planar format. For mmap() there is more than
   one image buffer available.

   The frame buffers provide the image buffering. In case the user process
   is a bit slow, this introduces lag and some undesired side-effects.
   The problem arises when the frame buffer is full. I used to drop the last
   frame, which makes the data in the queue stale very quickly. But dropping
   the frame at the head of the queue proved to be a litte bit more difficult.
   I tried a circular linked scheme, but this introduced more problems than
   it solved.

   Because filling and draining are completely asynchronous processes, this
   requires some fiddling with pointers and mutexes.

   Eventually, I came up with a system with 2 lists: an 'empty' frame list
   and a 'full' frame list:
     * Initially, all frame buffers but one are on the 'empty' list; the one
       remaining buffer is our initial fill frame.
     * If a frame is needed for filling, we try to take it from the 'empty' 
       list, unless that list is empty, in which case we take the buffer at 
       the head of the 'full' list.
     * When our fill buffer has been filled, it is appended to the 'full'
       list.
     * If a frame is needed by read() or mmap(), it is taken from the head of
       the 'full' list, handled, and then appended to the 'empty' list. If no
       buffer is present on the 'full' list, we wait.
   The advantage is that the buffer that is currently being decompressed/
   converted, is on neither list, and thus not in our way (any other scheme
   I tried had the problem of old data lingering in the queue).

   Whatever strategy you choose, it always remains a tradeoff: with more
   frame buffers the chances of a missed frame are reduced. On the other
   hand, on slower machines it introduces lag because the queue will
   always be full.
 */

/**
  \brief Find next frame buffer to fill. Take from empty or full list, whichever comes first.
 */
static inline int pwc_next_fill_frame(struct pwc_device *pdev)
{
        int ret;
        unsigned long flags;

        ret = 0;
        spin_lock_irqsave(&pdev->ptrlock, flags);
        if (pdev->fill_frame != NULL) {
                /* append to 'full' list */
                if (pdev->full_frames == NULL) {
                        pdev->full_frames = pdev->fill_frame;
                        pdev->full_frames_tail = pdev->full_frames;
                }
                else {
                        pdev->full_frames_tail->next = pdev->fill_frame;
                        pdev->full_frames_tail = pdev->fill_frame;
                }
        }
        if (pdev->empty_frames != NULL) {
                /* We have empty frames available. That's easy */
                pdev->fill_frame = pdev->empty_frames;
                pdev->empty_frames = pdev->empty_frames->next;
        }
        else {
                /* Hmm. Take it from the full list */
#if PWC_DEBUG
                /* sanity check */
                if (pdev->full_frames == NULL) {
                        Err("Neither empty or full frames available!\n");
                        spin_unlock_irqrestore(&pdev->ptrlock, flags);
                        return -EINVAL;
                }
#endif
                pdev->fill_frame = pdev->full_frames;
                pdev->full_frames = pdev->full_frames->next;
                ret = 1;
        }
        pdev->fill_frame->next = NULL;
#if PWC_DEBUG
        Trace(TRACE_SEQUENCE, "Assigning sequence number %d.\n", pdev->sequence);
        pdev->fill_frame->sequence = pdev->sequence++;
#endif
        spin_unlock_irqrestore(&pdev->ptrlock, flags);
        return ret;
}


/**
  \brief Reset all buffers, pointers and lists, except for the image_used[] buffer.

  If the image_used[] buffer is cleared too, mmap()/VIDIOCSYNC will run into trouble.
 */
static void pwc_reset_buffers(struct pwc_device *pdev)
{
        int i;
        unsigned long flags;

        spin_lock_irqsave(&pdev->ptrlock, flags);
        pdev->full_frames = NULL;
        pdev->full_frames_tail = NULL;
        for (i = 0; i < default_fbufs; i++) {
                pdev->fbuf[i].filled = 0;
                if (i > 0)
                        pdev->fbuf[i].next = &pdev->fbuf[i - 1];
                else
                        pdev->fbuf->next = NULL;
        }
        pdev->empty_frames = &pdev->fbuf[default_fbufs - 1];
        pdev->empty_frames_tail = pdev->fbuf;
        pdev->read_frame = NULL;
        pdev->fill_frame = pdev->empty_frames;
        pdev->empty_frames = pdev->empty_frames->next;

        pdev->image_read_pos = 0;
        pdev->fill_image = 0;
        spin_unlock_irqrestore(&pdev->ptrlock, flags);
}


/**
  \brief Do all the handling for getting one frame: get pointer, decompress, advance pointers.
 */
static int pwc_handle_frame(struct pwc_device *pdev)
{
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&pdev->ptrlock, flags);
        /* First grab our read_frame; this is removed from all lists, so
           we can release the lock after this without problems */
        if (pdev->read_frame != NULL) {
                /* This can't theoretically happen */
                Err("Huh? Read frame still in use?\n");
        }
        else {
                if (pdev->full_frames == NULL) {
                        Err("Woops. No frames ready.\n");
                }
                else {
                        pdev->read_frame = pdev->full_frames;
                        pdev->full_frames = pdev->full_frames->next;
                        pdev->read_frame->next = NULL;
                }

                if (pdev->read_frame != NULL) {
#if PWC_DEBUG
                        Trace(TRACE_SEQUENCE, "Decompressing frame %d\n", pdev->read_frame->sequence);
#endif
                        /* Decompression is a lenghty process, so it's outside of the lock.
                           This gives the isoc_handler the opportunity to fill more frames
                           in the mean time.
                        */
                        spin_unlock_irqrestore(&pdev->ptrlock, flags);
                        ret = pwc_decompress(pdev);
                        spin_lock_irqsave(&pdev->ptrlock, flags);

                        /* We're done with read_buffer, tack it to the end of the empty buffer list */
                        if (pdev->empty_frames == NULL) {
                                pdev->empty_frames = pdev->read_frame;
                                pdev->empty_frames_tail = pdev->empty_frames;
                        }
                        else {
                                pdev->empty_frames_tail->next = pdev->read_frame;
                                pdev->empty_frames_tail = pdev->read_frame;
                        }
                        pdev->read_frame = NULL;
                }
        }
        spin_unlock_irqrestore(&pdev->ptrlock, flags);
        return ret;
}

/**
  \brief Advance pointers of image buffer (after each user request)
*/
static inline void pwc_next_image(struct pwc_device *pdev)
{
        pdev->image_used[pdev->fill_image] = 0;
        pdev->fill_image = (pdev->fill_image + 1) % default_mbufs;
}



/* This gets called for the Isochronous pipe (video). This is done in
 * interrupt time, so it has to be fast, not crash, and not stall. Neat.
 */
static void pwc_isoc_handler(struct urb *urb)
{
        struct pwc_device *pdev;
        int i, fst, flen;
        int awake;
        struct pwc_frame_buf *fbuf;
        unsigned char *fillptr = 0, *iso_buf = 0;

        awake = 0;
        pdev = (struct pwc_device *)urb->context;
        if (pdev == NULL) {
                Err("isoc_handler() called with NULL device?!\n");
                return;
        }
#ifdef PWC_MAGIC
        if (pdev->magic != PWC_MAGIC) {
                Err("isoc_handler() called with bad magic!\n");
                return;
        }
#endif
        if (urb->status == -ENOENT || urb->status == -ECONNRESET) {
                Trace(TRACE_OPEN, "pwc_isoc_handler(): URB (%p) unlinked %ssynchronuously.\n", urb, urb->status == -ENOENT ? "" : "a");
                return;
        }
        if (urb->status != -EINPROGRESS && urb->status != 0) {
                const char *errmsg;

                errmsg = "Unknown";
                switch(urb->status) {
                        case -ENOSR:            errmsg = "Buffer error (overrun)"; break;
                        case -EPIPE:            errmsg = "Stalled (device not responding)"; break;
                        case -EOVERFLOW:        errmsg = "Babble (bad cable?)"; break;
                        case -EPROTO:           errmsg = "Bit-stuff error (bad cable?)"; break;
                        case -EILSEQ:           errmsg = "CRC/Timeout (could be anything)"; break;
                        case -ETIMEDOUT:        errmsg = "NAK (device does not respond)"; break;
                }
                Trace(TRACE_FLOW, "pwc_isoc_handler() called with status %d [%s].\n", urb->status, errmsg);
                /* Give up after a number of contiguous errors on the USB bus. 
                   Appearantly something is wrong so we simulate an unplug event.
                 */
                if (++pdev->visoc_errors > MAX_ISOC_ERRORS)
                {
                        Info("Too many ISOC errors, bailing out.\n");
                        pdev->error_status = EIO;
                        awake = 1;
                }
                else
                        return; // better luck next time
        }

        fbuf = pdev->fill_frame;
        if (fbuf == NULL) {
                Err("pwc_isoc_handler without valid fill frame.\n");
                awake = 1;
        }
        else {
                fillptr = fbuf->data + fbuf->filled;
        }
        /* Premature wakeup */
        if (awake) {
                wake_up_interruptible(&pdev->frameq);
                return;
        }

        /* Reset ISOC error counter. We did get here, after all. */
        pdev->visoc_errors = 0;

        /* vsync: 0 = don't copy data
                  1 = sync-hunt
                  2 = synched
         */
        /* Compact data */
        for (i = 0; i < urb->number_of_packets; i++) {
                fst  = urb->iso_frame_desc[i].status;
                flen = urb->iso_frame_desc[i].actual_length;
                iso_buf = urb->transfer_buffer + urb->iso_frame_desc[i].offset;
                if (fst == 0) {
                        if (flen > 0) { /* if valid data... */
                                if (pdev->vsync > 0) { /* ...and we are not sync-hunting... */
                                        pdev->vsync = 2;

                                        /* ...copy data to frame buffer, if possible */
                                        if (flen + fbuf->filled > pdev->frame_size) {
                                                Trace(TRACE_FLOW, "Frame buffer overflow (flen = %d, frame_size = %d).\n", flen, pdev->frame_size);
                                                pdev->vsync = 0; /* Hmm, let's wait for an EOF (end-of-frame) */
                                                pdev->vframes_error++;
                                        }
                                        else {
                                                memmove(fillptr, iso_buf, flen);
                                                fillptr += flen;
                                        }
                                }
                                fbuf->filled += flen;
                        } /* ..flen > 0 */

                        if (flen < pdev->vlast_packet_size) {
                                /* Shorter packet... We probably have the end of an image-frame; 
                                   wake up read() process and let select()/poll() do something.
                                   Decompression is done in user time over there.
                                 */
                                if (pdev->vsync == 2) {
                                        /* The ToUCam Fun CMOS sensor causes the firmware to send 2 or 3 bogus 
                                           frames on the USB wire after an exposure change. This conditition is 
                                           however detected  in the cam and a bit is set in the header.
                                         */
                                        if (pdev->type == 730) {
                                                unsigned char *ptr = (unsigned char *)fbuf->data;
                                                
                                                if (ptr[1] == 1 && ptr[0] & 0x10) {
#if PWC_DEBUG
                                                        Debug("Hyundai CMOS sensor bug. Dropping frame %d.\n", fbuf->sequence);
#endif
                                                        pdev->drop_frames += 2;
                                                        pdev->vframes_error++;
                                                }
                                                if ((ptr[0] ^ pdev->vmirror) & 0x01) {
                                                        if (ptr[0] & 0x01)
                                                                Info("Snapshot button pressed.\n");
                                                        else
                                                                Info("Snapshot button released.\n");
                                                }
                                                if ((ptr[0] ^ pdev->vmirror) & 0x02) {
                                                        if (ptr[0] & 0x02)
                                                                Info("Image is mirrored.\n");
                                                        else
                                                                Info("Image is normal.\n");
                                                }
                                                pdev->vmirror = ptr[0] & 0x03;
                                                /* Sometimes the trailer of the 730 is still sent as a 4 byte packet 
                                                   after a short frame; this condition is filtered out specifically. A 4 byte
                                                   frame doesn't make sense anyway.
                                                   So we get either this sequence: 
                                                        drop_bit set -> 4 byte frame -> short frame -> good frame
                                                   Or this one:
                                                        drop_bit set -> short frame -> good frame
                                                   So we drop either 3 or 2 frames in all!
                                                 */
                                                if (fbuf->filled == 4)
                                                        pdev->drop_frames++;
                                        }

                                        /* In case we were instructed to drop the frame, do so silently.
                                           The buffer pointers are not updated either (but the counters are reset below).
                                         */
                                        if (pdev->drop_frames > 0)
                                                pdev->drop_frames--;
                                        else {
                                                /* Check for underflow first */
                                                if (fbuf->filled < pdev->frame_size) {
                                                        Trace(TRACE_FLOW, "Frame buffer underflow (%d bytes); discarded.\n", fbuf->filled);
                                                        pdev->vframes_error++;
                                                }
                                                else {
                                                        /* Send only once per EOF */
                                                        awake = 1; /* delay wake_ups */

                                                        /* Find our next frame to fill. This will always succeed, since we
                                                         * nick a frame from either empty or full list, but if we had to
                                                         * take it from the full list, it means a frame got dropped.
                                                         */
                                                        if (pwc_next_fill_frame(pdev)) {
                                                                pdev->vframes_dumped++;
                                                                if ((pdev->vframe_count > FRAME_LOWMARK) && (pwc_trace & TRACE_FLOW)) {
                                                                        if (pdev->vframes_dumped < 20)
                                                                                Trace(TRACE_FLOW, "Dumping frame %d.\n", pdev->vframe_count);
                                                                        if (pdev->vframes_dumped == 20)
                                                                                Trace(TRACE_FLOW, "Dumping frame %d (last message).\n", pdev->vframe_count);
                                                                }
                                                        }
                                                        fbuf = pdev->fill_frame;
                                                }
                                        } /* !drop_frames */
                                        pdev->vframe_count++;
                                }
                                fbuf->filled = 0;
                                fillptr = fbuf->data;
                                pdev->vsync = 1;
                        } /* .. flen < last_packet_size */
                        pdev->vlast_packet_size = flen;
                } /* ..status == 0 */
#if PWC_DEBUG
                /* This is normally not interesting to the user, unless you are really debugging something */
                else {
                        static int iso_error = 0;
                        iso_error++;
                        if (iso_error < 20)
                                Trace(TRACE_FLOW, "Iso frame %d of USB has error %d\n", i, fst);
                }
#endif
        }
        if (awake)
                wake_up_interruptible(&pdev->frameq);
}


static int pwc_isoc_init(struct pwc_device *pdev)
{
        struct usb_device *udev;
        struct urb *urb;
        int i, j, ret;

        struct usb_interface_descriptor *idesc;

        if (pdev == NULL)
                return -EFAULT;
        if (pdev->iso_init)
                return 0;
        pdev->vsync = 0;
        udev = pdev->udev;

        /* Get the current alternate interface, adjust packet size */
        if (!udev->actconfig)
                return -EFAULT;
        idesc = &udev->actconfig->interface[0].altsetting[pdev->valternate];
        if (!idesc)
                return -EFAULT;

        /* Search video endpoint */
        pdev->vmax_packet_size = -1;
        for (i = 0; i < idesc->bNumEndpoints; i++)
                if ((idesc->endpoint[i].bEndpointAddress & 0xF) == pdev->vendpoint) {
                        pdev->vmax_packet_size = idesc->endpoint[i].wMaxPacketSize;
                        break;
                }
        
        if (pdev->vmax_packet_size < 0 || pdev->vmax_packet_size > ISO_MAX_FRAME_SIZE) {
                Err("Failed to find packet size for video endpoint in current alternate setting.\n");
                return -ENFILE; /* Odd error, that should be noticable */
        }

        /* Set alternate interface */
        ret = 0;
        Trace(TRACE_OPEN, "Setting alternate interface %d\n", pdev->valternate);
        ret = usb_set_interface(pdev->udev, 0, pdev->valternate);
        if (ret < 0)
                return ret;

        for (i = 0; i < MAX_ISO_BUFS; i++) {
                urb = usb_alloc_urb(ISO_FRAMES_PER_DESC);
                if (urb == NULL) {
                        Err("Failed to allocate urb %d\n", i);
                        ret = -ENOMEM;
                        break;
                }
                pdev->sbuf[i].urb = urb;
                Trace(TRACE_MEMORY, "Allocated URB at 0x%p\n", urb);
        }
        if (ret) {
                /* De-allocate in reverse order */
                while (i >= 0) {
                        if (pdev->sbuf[i].urb != NULL)
                                usb_free_urb(pdev->sbuf[i].urb);
                        pdev->sbuf[i].urb = NULL;
                        i--;
                }
                return ret;
        }

        /* init URB structure */        
        for (i = 0; i < MAX_ISO_BUFS; i++) {
                urb = pdev->sbuf[i].urb;

                urb->next = pdev->sbuf[(i + 1) % MAX_ISO_BUFS].urb;
                urb->dev = udev;
                urb->pipe = usb_rcvisocpipe(udev, pdev->vendpoint);
                urb->transfer_flags = USB_ISO_ASAP;
                urb->transfer_buffer = pdev->sbuf[i].data;
                urb->transfer_buffer_length = ISO_BUFFER_SIZE;
                urb->complete = pwc_isoc_handler;
                urb->context = pdev;
                urb->start_frame = 0;
                urb->number_of_packets = ISO_FRAMES_PER_DESC;
                for (j = 0; j < ISO_FRAMES_PER_DESC; j++) {
                        urb->iso_frame_desc[j].offset = j * ISO_MAX_FRAME_SIZE;
                        urb->iso_frame_desc[j].length = pdev->vmax_packet_size;
                }
        }

        /* link */
        for (i = 0; i < MAX_ISO_BUFS; i++) {
                ret = usb_submit_urb(pdev->sbuf[i].urb);
                if (ret)
                        Err("isoc_init() submit_urb %d failed with error %d\n", i, ret);
                else
                        Trace(TRACE_OPEN, "URB 0x%p submitted.\n", pdev->sbuf[i].urb);
        }

        /* All is done... */
        pdev->iso_init = 1;
        Trace(TRACE_OPEN, "<< pwc_isoc_init()\n");
        return 0;
}

static void pwc_isoc_cleanup(struct pwc_device *pdev)
{
        int i;
        
        Trace(TRACE_OPEN, ">> pwc_isoc_cleanup()\n");
        if (pdev == NULL)
                return;

        /* Unlinking ISOC buffers one by one */
        for (i = 0; i < MAX_ISO_BUFS; i++) {
                struct urb *urb;

                urb = pdev->sbuf[i].urb;
                if (urb != 0) {
                        if (pdev->iso_init) {
                                Trace(TRACE_MEMORY, "Unlinking URB %p\n", urb);
                                usb_unlink_urb(urb);
                        }
                        Trace(TRACE_MEMORY, "Freeing URB\n");
                        usb_free_urb(urb);
                        pdev->sbuf[i].urb = NULL;
                }
        }

        /* Stop camera, but only if we are sure the camera is still there (unplug
           is signalled by EPIPE) 
         */
        if (pdev->error_status && pdev->error_status != EPIPE) {
                Trace(TRACE_OPEN, "Setting alternate interface 0.\n");
                usb_set_interface(pdev->udev, 0, 0);
        }

        pdev->iso_init = 0;
        Trace(TRACE_OPEN, "<< pwc_isoc_cleanup()\n");
}

int pwc_try_video_mode(struct pwc_device *pdev, int width, int height, int new_fps, int new_compression, int new_snapshot)
{
        int ret;
        /* Stop isoc stuff */
        pwc_isoc_cleanup(pdev);
        /* Reset parameters */
        pwc_reset_buffers(pdev);
        /* Try to set video mode... */
        ret = pwc_set_video_mode(pdev, width, height, new_fps, new_compression, new_snapshot);
        if (ret) /* That failed... restore old mode (we know that worked) */
                ret = pwc_set_video_mode(pdev, pdev->view.x, pdev->view.y, pdev->vframes, pdev->vcompression, pdev->vsnapshot);
        if (!ret)
                if (pwc_isoc_init(pdev) < 0)
                        Info("Failed to restart ISOC transfers in pwc_try_video_mode.\n");
        pdev->drop_frames++; /* try to avoid garbage during switch */
        return ret;
}


/***************************************************************************/
/* Video4Linux functions */

static int pwc_video_open(struct video_device *vdev, int mode)
{
        int i;
        struct pwc_device *pdev;

        Trace(TRACE_OPEN, ">> video_open called(vdev = 0x%p).\n", vdev);
        
        if (vdev == NULL)
                BUG();
        pdev = (struct pwc_device *)vdev->priv;
        if (pdev == NULL)
                BUG();
        if (pdev->vopen)
                return -EBUSY;
        
        down(&pdev->modlock);
        if (!pdev->usb_init) {
                Trace(TRACE_OPEN, "Doing first time initialization.\n");
                pdev->usb_init = 1;
                
                {
                        /* Query sensor type */
                        const char *sensor_type = NULL;

                        i = pwc_get_cmos_sensor(pdev);
                        switch(i) {
                        case -1: /* Unknown, show nothing */; break;
                        case 0x00:  sensor_type = "Hyundai CMOS sensor"; break;
                        case 0x20:  sensor_type = "Sony CCD sensor + TDA8787"; break;
                        case 0x2E:  sensor_type = "Sony CCD sensor + Exas 98L59"; break;
                        case 0x2F:  sensor_type = "Sony CCD sensor + ADI 9804"; break;
                        case 0x30:  sensor_type = "Sharp CCD sensor + TDA8787"; break;
                        case 0x3E:  sensor_type = "Sharp CCD sensor + Exas 98L59"; break;
                        case 0x3F:  sensor_type = "Sharp CCD sensor + ADI 9804"; break;
                        case 0x40:  sensor_type = "UPA 1021 sensor"; break;
                        case 0x100: sensor_type = "VGA sensor"; break;
                        case 0x101: sensor_type = "PAL MR sensor"; break;
                        default:    sensor_type = "unknown type of sensor"; break;
                        }
                        if (sensor_type != NULL)
                                Info("This %s camera is equipped with a %s (%d).\n", pdev->vdev.name, sensor_type, i);
                }
        }

        /* Turn on camera */
        if (power_save) {
                i = pwc_camera_power(pdev, 1);
                if (i < 0)
                        Info("Failed to restore power to the camera! (%d)\n", i);
        }
        /* Set LED on/off time */
        if (pwc_set_leds(pdev, led_on, led_off) < 0)
                Info("Failed to set LED on/off time.\n");

        /* Find our decompressor, if any */
        pdev->decompressor = pwc_find_decompressor(pdev->type);
#if PWC_DEBUG   
        Debug("Found decompressor for %d at 0x%p\n", pdev->type, pdev->decompressor);
#endif

        /* So far, so good. Allocate memory. */
        i = pwc_allocate_buffers(pdev);
        if (i < 0) {
                Trace(TRACE_OPEN, "Failed to allocate buffer memory.\n");

                up(&pdev->modlock);
                return i;
        }
        
        /* Reset buffers & parameters */
        pwc_reset_buffers(pdev);
        for (i = 0; i < default_mbufs; i++)
                pdev->image_used[i] = 0;
        pdev->vframe_count = 0;
        pdev->vframes_dumped = 0;
        pdev->vframes_error = 0;
        pdev->visoc_errors = 0;
        pdev->error_status = 0;
#if PWC_DEBUG
        pdev->sequence = 0;
#endif

        /* Set some defaults */
        pdev->vsnapshot = 0;

        /* Start iso pipe for video; first try the last used video size
           (or the default one); if that fails try QCIF/10 or QSIF/10;
           it that fails too, give up.
         */
        i = pwc_set_video_mode(pdev, pwc_image_sizes[pdev->vsize].x, pwc_image_sizes[pdev->vsize].y, pdev->vframes, pdev->vcompression, 0);
        if (i)  {
                Trace(TRACE_OPEN, "First attempt at set_video_mode failed.\n");
                if (pdev->type == 730 || pdev->type == 740 || pdev->type == 750)
                        i = pwc_set_video_mode(pdev, pwc_image_sizes[PSZ_QSIF].x, pwc_image_sizes[PSZ_QSIF].y, 10, pdev->vcompression, 0);
                else
                        i = pwc_set_video_mode(pdev, pwc_image_sizes[PSZ_QCIF].x, pwc_image_sizes[PSZ_QCIF].y, 10, pdev->vcompression, 0);
        }
        if (i) {
                Trace(TRACE_OPEN, "Second attempt at set_video_mode failed.\n");
                up(&pdev->modlock);
                return i;
        }
        
        i = pwc_isoc_init(pdev);
        if (i) {
                Trace(TRACE_OPEN, "Failed to init ISOC stuff = %d.\n", i);
                up(&pdev->modlock);
                return i;
        }

        pdev->vopen++;
        /* lock decompressor; this has a small race condition, since we 
           could in theory unload pwcx.o between pwc_find_decompressor()
           above and this call. I doubt it's ever going to be a problem.
         */
        if (pdev->decompressor != NULL)
                pdev->decompressor->lock();
        up(&pdev->modlock);
        Trace(TRACE_OPEN, "<< video_open() returns 0.\n");
        return 0;
}

/* Note that all cleanup is done in the reverse order as in _open */
static void pwc_video_close(struct video_device *vdev)
{
        struct pwc_device *pdev;
        int i;

        Trace(TRACE_OPEN, ">> video_close called(vdev = 0x%p).\n", vdev);

        pdev = (struct pwc_device *)vdev->priv;
        if (pdev->vopen == 0)
                Info("video_close() called on closed device?\n");

        /* Dump statistics, but only if a reasonable amount of frames were
           processed (to prevent endless log-entries in case of snap-shot
           programs) 
         */
        if (pdev->vframe_count > 20)
                Info("Closing video device: %d frames received, dumped %d frames, %d frames with errors.\n", pdev->vframe_count, pdev->vframes_dumped, pdev->vframes_error);

        if (pdev->decompressor != NULL) {
                pdev->decompressor->exit();
                pdev->decompressor->unlock();
                pdev->decompressor = NULL;
        }

        pwc_isoc_cleanup(pdev);
        pwc_free_buffers(pdev);

        /* Turn off LEDS and power down camera, but only when not unplugged */
        if (pdev->error_status != EPIPE) {
                if (pwc_set_leds(pdev, 0, 0) < 0)
                        Info("Failed to set LED on/off time.\n");
                if (power_save) {
                        i = pwc_camera_power(pdev, 0);
                        if (i < 0) 
                                Err("Failed to power down camera (%d)\n", i);
                }
        }
        pdev->vopen = 0;
        Trace(TRACE_OPEN, "<< video_close()\n");
}

/*
 *      FIXME: what about two parallel reads ????
 *      ANSWER: Not supported. You can't open the device more than once,
                despite what the V4L1 interface says. First, I don't see
                the need, second there's no mechanism of alerting the
                2nd/3rd/... process of events like changing image size.
                And I don't see the point of blocking that for the
                2nd/3rd/... process.
                In multi-threaded environments reading parallel from any
                device is tricky anyhow.
 */

static long pwc_video_read(struct video_device *vdev, char *buf, unsigned long count, int noblock)
{
        struct pwc_device *pdev;
        DECLARE_WAITQUEUE(wait, current);

        Trace(TRACE_READ, "video_read(0x%p, %p, %ld, %d) called.\n", vdev, buf, count, noblock);
        if (vdev == NULL)
                return -EFAULT;
        pdev = vdev->priv;
        if (pdev == NULL)
                return -EFAULT;
        if (pdev->error_status)
                return -pdev->error_status; /* Something happened, report what. */

        /* In case we're doing partial reads, we don't have to wait for a frame */
        if (pdev->image_read_pos == 0) {
                /* Do wait queueing according to the (doc)book */
                add_wait_queue(&pdev->frameq, &wait);
                while (pdev->full_frames == NULL) {
                        /* Check for unplugged/etc. here */
                        if (pdev->error_status) {
                                remove_wait_queue(&pdev->frameq, &wait);
                                set_current_state(TASK_RUNNING);
                                return -pdev->error_status ;
                        }
                        if (noblock) {
                                remove_wait_queue(&pdev->frameq, &wait);
                                set_current_state(TASK_RUNNING);
                                return -EWOULDBLOCK;
                        }
                        if (signal_pending(current)) {
                                remove_wait_queue(&pdev->frameq, &wait);
                                set_current_state(TASK_RUNNING);
                                return -ERESTARTSYS;
                        }
                        schedule();
                        set_current_state(TASK_INTERRUPTIBLE);
                }
                remove_wait_queue(&pdev->frameq, &wait);
                set_current_state(TASK_RUNNING);

                /* Decompress and release frame */
                if (pwc_handle_frame(pdev))
                        return -EFAULT;
        }

        Trace(TRACE_READ, "Copying data to user space.\n");
        /* copy bytes to user space; we allow for partial reads */
        if (count + pdev->image_read_pos > pdev->view.size)
                count = pdev->view.size - pdev->image_read_pos;
        if (copy_to_user(buf, pdev->image_ptr[pdev->fill_image] + pdev->image_read_pos, count))
                return -EFAULT;
        pdev->image_read_pos += count;
        if (pdev->image_read_pos >= pdev->view.size) { /* All data has been read */
                pdev->image_read_pos = 0;
                pwc_next_image(pdev);
        }
        return count;
}


static long pwc_video_write(struct video_device *vdev, const char *buf, unsigned long count, int noblock)
{
        return -EINVAL;
}

static unsigned int pwc_video_poll(struct video_device *vdev, struct file *file, poll_table *wait)
{
        struct pwc_device *pdev;

        if (vdev == NULL)
                return -EFAULT;
        pdev = vdev->priv;
        if (pdev == NULL)
                return -EFAULT;

        poll_wait(file, &pdev->frameq, wait);
        if (pdev->error_status)
                return POLLERR;
        if (pdev->full_frames != NULL) /* we have frames waiting */
                return (POLLIN | POLLRDNORM);

        return 0;
}

static int pwc_video_ioctl(struct video_device *vdev, unsigned int cmd, void *arg)
{
        struct pwc_device *pdev;
        DECLARE_WAITQUEUE(wait, current);

        if (vdev == NULL)
                return -EFAULT;
        pdev = vdev->priv;
        if (pdev == NULL)
                return -EFAULT;

        switch (cmd) {
                /* Query cabapilities */
                case VIDIOCGCAP:
                {
                        struct video_capability caps;

                        strcpy(caps.name, vdev->name);
                        caps.type = VID_TYPE_CAPTURE;
                        caps.channels = 1;
                        caps.audios = 1;
                        caps.minwidth  = pdev->view_min.x;
                        caps.minheight = pdev->view_min.y;
                        caps.maxwidth  = pdev->view_max.x;
                        caps.maxheight = pdev->view_max.y;
                        if (copy_to_user(arg, &caps, sizeof(caps)))
                                return -EFAULT;
                        break;
                }

                /* Channel functions (simulate 1 channel) */
                case VIDIOCGCHAN:
                {
                        struct video_channel v;

                        if (copy_from_user(&v, arg, sizeof(v)))
                                return -EFAULT;
                        if (v.channel != 0)
                                return -EINVAL;

                        v.flags = 0;
                        v.tuners = 0;
                        v.type = VIDEO_TYPE_CAMERA;
                        strcpy(v.name, "Webcam");

                        if (copy_to_user(arg, &v, sizeof(v)))
                                return -EFAULT;

                        return 0;
                }

                case VIDIOCSCHAN:
                {       
                        /* The spec says the argument is an integer, but
                           the bttv driver uses a video_channel arg, which
                           makes sense becasue it also has the norm flag.
                         */
                        struct video_channel v;

                        if (copy_from_user(&v, arg, sizeof(v)))
                                return -EFAULT;

                        if (v.channel != 0)
                                return -EINVAL;

                        return 0;
                }


                /* Picture functions; contrast etc. */
                case VIDIOCGPICT:
                {
                        struct video_picture p;
                        int val;

                        p.colour = 0x8000;
                        p.hue = 0x8000;
                        val = pwc_get_brightness(pdev);
                        if (val >= 0)
                                p.brightness = val;
                        else
                                p.brightness = 0xffff;
                        val = pwc_get_contrast(pdev);
                        if (val >= 0)
                                p.contrast = val;
                        else
                                p.contrast = 0xffff;
                        /* Gamma, Whiteness, what's the difference? :) */
                        val = pwc_get_gamma(pdev);
                        if (val >= 0)
                                p.whiteness = val;
                        else
                                p.whiteness = 0xffff;
                        val = pwc_get_saturation(pdev);
                        if (val >= 0)
                                p.colour = val;
                        else
                                p.colour = 0xffff;
                        p.depth = 24;
                        p.palette = VIDEO_PALETTE_YUV420P;
                        p.hue = 0xFFFF; /* N/A */

                        if (copy_to_user(arg, &p, sizeof(p)))
                                return -EFAULT;
                        break;
                }
                
                case VIDIOCSPICT:
                {
                        struct video_picture p;

                        if (copy_from_user(&p, arg, sizeof(p)))
                                return -EFAULT;

                        /*
                         *      FIXME:  Suppose we are mid read
                                ANSWER: No problem: the firmware of the camera
                                        can handle brightness/contrast/etc
                                        changes at _any_ time, and the palette
                                        is used exactly once in the uncompress
                                        routine.
                         */
                        pwc_set_brightness(pdev, p.brightness);
                        pwc_set_contrast(pdev, p.contrast);
                        pwc_set_gamma(pdev, p.whiteness);
                        pwc_set_saturation(pdev, p.colour);
                        if (p.palette && p.palette != VIDEO_PALETTE_YUV420P) {
                                return -EINVAL;
                        }
                        break;
                }

                /* Window/size parameters */            
                case VIDIOCGWIN:
                {
                        struct video_window vw;
                        
                        vw.x = 0;
                        vw.y = 0;
                        vw.width = pdev->view.x;
                        vw.height = pdev->view.y;
                        vw.chromakey = 0;
                        vw.flags = (pdev->vframes << PWC_FPS_SHIFT) | 
                                   (pdev->vsnapshot ? PWC_FPS_SNAPSHOT : 0);
                        
                        if (copy_to_user(arg, &vw, sizeof(vw)))
                                return -EFAULT;                 
                        break;
                }
                
                case VIDIOCSWIN:
                {
                        struct video_window vw;
                        int fps, snapshot, ret;
                
                        if (copy_from_user(&vw, arg, sizeof(vw)))
                                return -EFAULT;

                        fps = (vw.flags & PWC_FPS_FRMASK) >> PWC_FPS_SHIFT;
                        snapshot = vw.flags & PWC_FPS_SNAPSHOT;
                        if (fps == 0)
                                fps = pdev->vframes;
                        if (pdev->view.x == vw.width && pdev->view.y && fps == pdev->vframes && snapshot == pdev->vsnapshot)
                                return 0;
                        ret = pwc_try_video_mode(pdev, vw.width, vw.height, fps, pdev->vcompression, snapshot);
                        if (ret)
                                return ret;
                        break;          
                }
                
                /* We don't have overlay support (yet) */
                case VIDIOCGFBUF:
                {
                        struct video_buffer vb;
                        
                        vb.base = NULL;
                        vb.height = 0;
                        vb.width = 0;
                        vb.depth = 0;
                        vb.bytesperline = 0;
                        
                        if (copy_to_user((void *)arg, (void *)&vb, sizeof(vb)))
                                return -EFAULT;
                        break;
                }

                /* mmap() functions */
                case VIDIOCGMBUF:
                {
                        /* Tell the user program how much memory is needed for a mmap() */
                        struct video_mbuf vm;
                        int i;

                        memset(&vm, 0, sizeof(vm));
                        vm.size = default_mbufs * pdev->len_per_image;
                        vm.frames = default_mbufs; /* double buffering should be enough for most applications */
                        for (i = 0; i < default_mbufs; i++)
                                vm.offsets[i] = i * pdev->len_per_image;

                        if (copy_to_user((void *)arg, (void *)&vm, sizeof(vm)))
                                return -EFAULT;
                        break;
                }

                case VIDIOCMCAPTURE:
                {
                        /* Start capture into a given image buffer (called 'frame' in video_mmap structure) */
                        struct video_mmap vm;

                        if (copy_from_user((void *)&vm, (void *)arg, sizeof(vm)))
                                return -EFAULT;
                        Trace(TRACE_READ, "VIDIOCMCAPTURE: %dx%d, frame %d, format %d\n", vm.width, vm.height, vm.frame, vm.format);
                        if (vm.frame < 0 || vm.frame >= default_mbufs)
                                return -EINVAL;

                        /* xawtv is nasty. It probes the available palettes
                           by setting a very small image size and trying
                           various palettes... The driver doesn't support
                           such small images, so I'm working around it.
                         */
                        if (vm.format && vm.format != VIDEO_PALETTE_YUV420P)
                                return -EINVAL;
                         
                        if ((vm.width != pdev->view.x || vm.height != pdev->view.y) &&
                            (vm.width >= pdev->view_min.x && vm.height >= pdev->view_min.y)) {
                                int ret;
                                
                                Trace(TRACE_OPEN, "VIDIOCMCAPTURE: changing size to please xawtv :-(.\n");
                                ret = pwc_try_video_mode(pdev, vm.width, vm.height, pdev->vframes, pdev->vcompression, pdev->vsnapshot);
                                if (ret)
                                        return ret;
                        } /* ... size mismatch */

                        /* FIXME: should we lock here? */
                        if (pdev->image_used[vm.frame])
                                return -EBUSY;  /* buffer wasn't available. Bummer */
                        pdev->image_used[vm.frame] = 1;

                        /* Okay, we're done here. In the SYNC call we wait until a 
                           frame comes available, then expand image into the given 
                           buffer.
                           In contrast to the CPiA cam the Philips cams deliver a
                           constant stream, almost like a grabber card. Also,
                           we have separate buffers for the rawdata and the image,
                           meaning we can nearly always expand into the requested buffer.
                         */
                        Trace(TRACE_READ, "VIDIOCMCAPTURE done.\n");
                        break;
                }

                case VIDIOCSYNC:
                {
                        /* The doc says: "Whenever a buffer is used it should
                           call VIDIOCSYNC to free this frame up and continue."
                           
                           The only odd thing about this whole procedure is 
                           that MCAPTURE flags the buffer as "in use", and
                           SYNC immediately unmarks it, while it isn't 
                           after SYNC that you know that the buffer actually
                           got filled! So you better not start a CAPTURE in
                           the same frame immediately (use double buffering). 
                           This is not a problem for this cam, since it has 
                           extra intermediate buffers, but a hardware 
                           grabber card will then overwrite the buffer 
                           you're working on.
                         */
                        int mbuf, ret;

                        if (copy_from_user((void *)&mbuf, arg, sizeof(int)))
                                return -EFAULT;

                        Trace(TRACE_READ, "VIDIOCSYNC called (%d).\n", mbuf);

                        /* bounds check */
                        if (mbuf < 0 || mbuf >= default_mbufs)
                                return -EINVAL;
                        /* check if this buffer was requested anyway */
                        if (pdev->image_used[mbuf] == 0)
                                return -EINVAL;

                        /* Add ourselves to the frame wait-queue.
                           In the loop, check for error conditions and signals.

                           FIXME: needs auditing for safety.
                           QUESTION: In what respect? I think that using the
                                     frameq is safe now.
                         */
                        add_wait_queue(&pdev->frameq, &wait);
                        while (pdev->full_frames == NULL) {
                                if (pdev->error_status) {
                                        remove_wait_queue(&pdev->frameq, &wait);
                                        set_current_state(TASK_RUNNING);
                                        return -pdev->error_status;
                                }
                                if (signal_pending(current)) {
                                        remove_wait_queue(&pdev->frameq, &wait);
                                        set_current_state(TASK_RUNNING);
                                        return -ERESTARTSYS;
                                }
                                schedule();
                                set_current_state(TASK_INTERRUPTIBLE);
                        }
                        remove_wait_queue(&pdev->frameq, &wait);
                        set_current_state(TASK_RUNNING);
                                
                        /* The frame is ready. Expand in the image buffer 
                           requested by the user. I don't care if you 
                           mmap() 5 buffers and request data in this order: 
                           buffer 4 2 3 0 1 2 3 0 4 3 1 . . .
                           Grabber hardware may not be so forgiving.
                         */
                        Trace(TRACE_READ, "VIDIOCSYNC: frame ready.\n");
                        pdev->fill_image = mbuf; /* tell in which buffer we want the image to be expanded */
                        /* Decompress, etc */
                        ret = pwc_handle_frame(pdev);
                        pdev->image_used[mbuf] = 0;
                        if (ret)
                                return -EFAULT;
                        break;
                }
                
                case VIDIOCGAUDIO:
                {
                        struct video_audio v;
                        
                        strcpy(v.name, "Microphone");
                        v.audio = -1; /* unknown audio minor */
                        v.flags = 0;
                        v.mode = VIDEO_SOUND_MONO;
                        v.volume = 0;
                        v.bass = 0;
                        v.treble = 0;
                        v.balance = 0x8000;
                        v.step = 1;
                        
                        if (copy_to_user(arg, &v, sizeof(v)))
                                return -EFAULT;
                        break;  
                }
                
                case VIDIOCSAUDIO:
                {
                        struct video_audio v;
                        
                        if (copy_from_user(&v, arg, sizeof(v)))
                                return -EFAULT;
                        /* Dummy: nothing can be set */
                        break;
                }
                
                case VIDIOCGUNIT:
                {
                        struct video_unit vu;
                        
                        vu.video = pdev->vdev.minor & 0x3F;
                        vu.audio = -1; /* not known yet */
                        vu.vbi = -1;
                        vu.radio = -1;
                        vu.teletext = -1;
                        if (copy_to_user(arg, &vu, sizeof(vu)))
                                return -EFAULT;
                        break;
                }
                default:
                        return pwc_ioctl(pdev, cmd, arg);
        } /* ..switch */
        return 0;
}       

static int pwc_video_mmap(struct video_device *vdev, const char *adr, unsigned long size)
{
        struct pwc_device *pdev;
        unsigned long start = (unsigned long)adr;
        unsigned long page, pos;
        
        Trace(TRACE_MEMORY, "mmap(0x%p, 0x%p, %lu) called.\n", vdev, adr, size);
        pdev = vdev->priv;

        pos = (unsigned long)pdev->image_data;
        while (size > 0) {
                page = kvirt_to_pa(pos);
                if (remap_page_range(start, page, PAGE_SIZE, PAGE_SHARED))
                        return -EAGAIN;

                start += PAGE_SIZE;
                pos += PAGE_SIZE;
                if (size > PAGE_SIZE)
                        size -= PAGE_SIZE;
                else
                        size = 0;
        }

        return 0;
}

/***************************************************************************/
/* USB functions */

/* This function gets called when a new device is plugged in or the usb core
 * is loaded.
 */

static void *usb_pwc_probe(struct usb_device *udev, unsigned int ifnum, const struct usb_device_id *id)
{
        struct pwc_device *pdev = NULL;
        int vendor_id, product_id, type_id;
        int i, hint;
        int video_nr = -1; /* default: use next available device */
        char serial_number[30], *name;

        /* Check if we can handle this device */
        Trace(TRACE_PROBE, "probe() called [%04X %04X], if %d\n", udev->descriptor.idVendor, udev->descriptor.idProduct, ifnum);

        /* the interfaces are probed one by one. We are only interested in the
           video interface (0) now.
           Interface 1 is the Audio Control, and interface 2 Audio itself.
         */
        if (ifnum > 0) 
                return NULL;

        vendor_id = udev->descriptor.idVendor;
        product_id = udev->descriptor.idProduct;

        if (vendor_id == 0x0471) {
                switch (product_id) {
                case 0x0302:
                        Info("Philips PCA645VC USB webcam detected.\n");
                        name = "Philips 645 webcam";
                        type_id = 645;
                        break;
                case 0x0303:
                        Info("Philips PCA646VC USB webcam detected.\n");
                        name = "Philips 646 webcam";
                        type_id = 646;
                        break;
                case 0x0304:
                        Info("Askey VC010 type 2 USB webcam detected.\n");
                        name = "Askey VC010 webcam";
                        type_id = 646;
                        break;
                case 0x0307:
                        Info("Philips PCVC675K (Vesta) USB webcam detected.\n");
                        name = "Philips 675 webcam";
                        type_id = 675;
                        break;
                case 0x0308:
                        Info("Philips PCVC680K (Vesta Pro) USB webcam detected.\n");
                        name = "Philips 680 webcam";
                        type_id = 680;
                        break;
                case 0x030C:
                        Info("Philips PCVC690K (Vesta Pro Scan) USB webcam detected.\n");
                        name = "Philips 690 webcam";
                        type_id = 690;
                        break;
                case 0x0310:
                        Info("Philips PCVC730K (ToUCam Fun) USB webcam detected.\n");
                        name = "Philips 730 webcam";
                        type_id = 730;
                        break;
                case 0x0311:
                        Info("Philips PCVC740K (ToUCam Pro) USB webcam detected.\n");
                        name = "Philips 740 webcam";
                        type_id = 740;
                        break;
                case 0x0312:
                        Info("Philips PCVC750K (ToUCam Pro Scan) USB webcam detected.\n");
                        name = "Philips 750 webcam";
                        type_id = 750;
                        break;
                case 0x0313:
                        Info("Philips PCVC720K/40 (ToUCam XS) USB webcam detected.\n");
                        name = "Philips 720 webcam";
                        type_id = 720;
                        break;
                default:
                        return NULL;
                        break;
                }
        }
        else if (vendor_id == 0x069A) {
                switch(product_id) {
                case 0x0001:
                        Info("Askey VC010 type 1 USB webcam detected.\n");
                        name = "Askey VC010 webcam";
                        type_id = 645;
                        break;
                default:
                        return NULL;
                        break;
                }
        }
        else if (vendor_id == 0x046d) {
                switch(product_id) {
                case 0x08b0:
                        Info("Logitech QuickCam Pro 3000 USB webcam detected.\n");
                        name = "Logitech QuickCam Pro 3000";
                        type_id = 740; /* CCD sensor */
                        break;
                case 0x08b1:
                        Info("Logitech QuickCam for Notebook Pro USB webcam detected.\n");
                        name = "Logitech QuickCam Notebook Pro";
                        type_id = 740; /* CCD sensor */
                        break;
                case 0x08b2:
                        Info("Logitech QuickCam 4000 Pro USB webcam detected.\n");
                        name = "Logitech QuickCam Pro 4000";
                        type_id = 740; /* CCD sensor */
                        break;
                case 0x08b3:
                        Info("Logitech QuickCam Zoom USB webcam detected.\n");
                        name = "Logitech QuickCam Zoom";
                        type_id = 740; /* CCD sensor */
                        break;
                case 0x08b4:
                case 0x08b5:
                case 0x08b6:
                case 0x08b7:
                case 0x08b8:
                        Info("Logitech QuickCam detected (reserved ID).\n");
                        name = "Logitech QuickCam (res.)";
                        type_id = 730; /* Assuming CMOS */
                        break;
                default:
                        return NULL;
                        break;
                }
        }
        else if (vendor_id == 0x055d) {
                /* I don't know the difference between the C10 and the C30;
                   I suppose the difference is the sensor, but both cameras
                   work equally well with a type_id of 675
                 */
                switch(product_id) {
                case 0x9000:
                        Info("Samsung MPC-C10 USB webcam detected.\n");
                        name = "Samsung MPC-C10";
                        type_id = 675;
                        break;
                case 0x9001:
                        Info("Samsung MPC-C30 USB webcam detected.\n");
                        name = "Samsung MPC-C30";
                        type_id = 675;
                        break;
                default:
                        return NULL;
                        break;
                }
        }
        else if (vendor_id == 0x041e) {
                switch(product_id) {
                case 0x400c:
                        Info("Creative Labs Webcam 5 detected.\n");
                        name = "Creative Labs Webcam 5";
                        type_id = 730;
                        break;
                case 0x4011:
                        Info("Creative Labs Webcam Pro Ex detected.\n");
                        name = "Creative Labs Webcam Pro Ex";
                        type_id = 740;
                        break;
                default:
                        return NULL;
                        break;
                }
        }
        else if (vendor_id == 0x04cc) { 
                switch(product_id) {
                case 0x8116:
                        Info("Sotec Afina Eye USB webcam detected.\n");
                        name = "Sotec Afina Eye";
                        type_id = 730;
                        break;  
                default:
                        return NULL;
                        break;
                }
        }
        else if (vendor_id == 0x0d81) {
                switch(product_id) {
                case 0x1900:
                        Info("Visionite VCS-UC300 USB webcam detected.\n");
                        name = "Visionite VCS-UC300";
                        type_id = 740; /* CCD sensor */
                        break;
                case 0x1910:
                        Info("Visionite VCS-UM100 USB webcam detected.\n");
                        name = "Visionite VCS-UM100";
                        type_id = 730; /* CMOS sensor */
                        break;
                default:
                        return NULL;
                        break;
                }
        }
        else 
                return NULL; /* Not any of the know types; but the list keeps growing. */

        memset(serial_number, 0, 30);
        usb_string(udev, udev->descriptor.iSerialNumber, serial_number, 29);
        Trace(TRACE_PROBE, "Device serial number is %s\n", serial_number);

        if (udev->descriptor.bNumConfigurations > 1)
                Info("Warning: more than 1 configuration available.\n");

        /* Allocate structure, initialize pointers, mutexes, etc. and link it to the usb_device */
        pdev = kmalloc(sizeof(struct pwc_device), GFP_KERNEL);
        if (pdev == NULL) {
                Err("Oops, could not allocate memory for pwc_device.\n");
                return NULL;
        }
        memset(pdev, 0, sizeof(struct pwc_device));
        pdev->type = type_id;
        pwc_construct(pdev);
        pdev->vsize = default_size;
        pdev->vframes = default_fps;

        init_MUTEX(&pdev->modlock);
        pdev->ptrlock = SPIN_LOCK_UNLOCKED;

        pdev->udev = udev;
        init_waitqueue_head(&pdev->frameq);
        pdev->vcompression = pwc_preferred_compression;

        memcpy(&pdev->vdev, &pwc_template, sizeof(pwc_template));
        strcpy(pdev->vdev.name, name);
        SET_MODULE_OWNER(&pdev->vdev);
        pdev->vdev.priv = pdev;

        pdev->release = udev->descriptor.bcdDevice;
        Trace(TRACE_PROBE, "Release: %04x\n", pdev->release);

        /* Now search device_hint[] table for a match, so we can hint a node number. */
        for (hint = 0; hint < MAX_DEV_HINTS; hint++) {
                if (((device_hint[hint].type == -1) || (device_hint[hint].type == pdev->type)) &&
                     (device_hint[hint].pdev == NULL)) {
                        /* so far, so good... try serial number */
                        if ((device_hint[hint].serial_number[0] == '*') || !strcmp(device_hint[hint].serial_number, serial_number)) {
                                /* match! */
                                video_nr = device_hint[hint].device_node;
                                Trace(TRACE_PROBE, "Found hint, will try to register as /dev/video%d\n", video_nr);
                                break;
                        }
                }
        }

        i = video_register_device(&pdev->vdev, VFL_TYPE_GRABBER, video_nr);
        if (i < 0) {
                Err("Failed to register as video device (%d).\n", i);
                kfree(pdev); /* Oops, no memory leaks please */
                return NULL;
        }
        else {
                Info("Registered as /dev/video%d.\n", pdev->vdev.minor & 0x3F);
        }
        /* occupy slot */
        if (hint < MAX_DEV_HINTS) 
                device_hint[hint].pdev = pdev;

        Trace(TRACE_PROBE, "probe() function returning struct at 0x%p.\n", pdev);
        return pdev;
}

/* The user janked out the cable... */
static void usb_pwc_disconnect(struct usb_device *udev, void *ptr)
{
        struct pwc_device *pdev;
        int hint;

        lock_kernel();
        pdev = (struct pwc_device *)ptr;
        if (pdev == NULL) {
                Err("pwc_disconnect() Called without private pointer.\n");
                unlock_kernel();
                return;
        }
        if (pdev->udev == NULL) {
                Err("pwc_disconnect() already called for %p\n", pdev);
                unlock_kernel();
                return;
        }
        if (pdev->udev != udev) {
                Err("pwc_disconnect() Woops: pointer mismatch udev/pdev.\n");
                unlock_kernel();
                return;
        }
#ifdef PWC_MAGIC
        if (pdev->magic != PWC_MAGIC) {
                Err("pwc_disconnect() Magic number failed. Consult your scrolls and try again.\n");
                unlock_kernel();
                return;
        }
#endif  

        /* We got unplugged; this is signalled by an EPIPE error code */
        if (pdev->vopen) {
                Info("Disconnected while webcam is in use!\n");
                pdev->error_status = EPIPE;
        }
        
        /* Alert waiting processes */
        wake_up_interruptible(&pdev->frameq);
        /* Wait until device is closed */
        while (pdev->vopen)
                schedule();
        /* Device is now closed, so we can safely unregister it */
        Trace(TRACE_PROBE, "Unregistering video device in disconnect().\n");
        video_unregister_device(&pdev->vdev); 

        /* Free memory (don't set pdev to 0 just yet) */
        kfree(pdev);

        /* search device_hint[] table if we occupy a slot, by any chance */
        for (hint = 0; hint < MAX_DEV_HINTS; hint++)
                if (device_hint[hint].pdev == pdev)
                        device_hint[hint].pdev = NULL;

        unlock_kernel();
}


/* *grunt* We have to do atoi ourselves :-( */
static int pwc_atoi(const char *s)
{
        int k = 0;
        
        k = 0;
        while (*s != '\0' && *s >= '0' && *s <= '9') {
                k = 10 * k + (*s - '0');
                s++;
        }
        return k;
}


/* 
 * Initialization code & module stuff 
 */

static char *size = NULL;
static int fps = 0;
static int fbufs = 0;
static int mbufs = 0;
static int trace = -1;
static int compression = -1;
static int leds[2] = { -1, -1 };
static char *dev_hint[MAX_DEV_HINTS] = { };

MODULE_PARM(size, "s");
MODULE_PARM_DESC(size, "Initial image size. One of sqcif, qsif, qcif, sif, cif, vga");
MODULE_PARM(fps, "i");
MODULE_PARM_DESC(fps, "Initial frames per second. Varies with model, useful range 5-30");
MODULE_PARM(fbufs, "i");
MODULE_PARM_DESC(fbufs, "Number of internal frame buffers to reserve");
MODULE_PARM(mbufs, "i");
MODULE_PARM_DESC(mbufs, "Number of external (mmap()ed) image buffers");
MODULE_PARM(trace, "i");
MODULE_PARM_DESC(trace, "For debugging purposes");
MODULE_PARM(power_save, "i");
MODULE_PARM_DESC(power_save, "Turn power save feature in camera on or off");
MODULE_PARM(compression, "i");
MODULE_PARM_DESC(compression, "Preferred compression quality. Range 0 (uncompressed) to 3 (high compression)");
MODULE_PARM(leds, "2i");
MODULE_PARM_DESC(leds, "LED on,off time in milliseconds");
MODULE_PARM(dev_hint, "0-20s");
MODULE_PARM_DESC(dev_hint, "Device node hints");

MODULE_DESCRIPTION("Philips USB & OEM webcam driver");
MODULE_AUTHOR("Nemosoft Unv. <nemosoft@smcc.demon.nl>");
MODULE_LICENSE("GPL");

static int __init usb_pwc_init(void)
{
        int i, sz;
        char *sizenames[PSZ_MAX] = { "sqcif", "qsif", "qcif", "sif", "cif", "vga" };

        Info("Philips PCA645/646 + PCVC675/680/690 + PCVC730/740/750 webcam module version " PWC_VERSION " loaded.\n");
        Info("Also supports the Askey VC010, various Logitech Quickcams, Samsung MPC-C10 and MPC-C30,\n");
        Info("the Creative WebCam 5, SOTEC Afina Eye and Visionite VCS-UC300 and VCS-UM100.\n");

        if (fps) {
                if (fps < 4 || fps > 30) {
                        Err("Framerate out of bounds (4-30).\n");
                        return -EINVAL;
                }
                default_fps = fps;
                Info("Default framerate set to %d.\n", default_fps);
        }
        
        if (size) {
                /* string; try matching with array */
                for (sz = 0; sz < PSZ_MAX; sz++) {
                        if (!strcmp(sizenames[sz], size)) { /* Found! */
                                default_size = sz;
                                break;
                        }
                }
                if (sz == PSZ_MAX) {
                        Err("Size not recognized; try size=[sqcif | qsif | qcif | sif | cif | vga].\n");
                        return -EINVAL;
                }
                Info("Default image size set to %s [%dx%d].\n", sizenames[default_size], pwc_image_sizes[default_size].x, pwc_image_sizes[default_size].y);
        }
        if (mbufs) {

                if (mbufs < 1 || mbufs > MAX_IMAGES) {
                        Err("Illegal number of mmap() buffers; use a number between 1 and %d.\n", MAX_IMAGES);
                        return -EINVAL;
                }
                default_mbufs = mbufs;
                Info("Number of image buffers set to %d.\n", default_mbufs);
        }
        if (fbufs) {
                if (fbufs < 2 || fbufs > MAX_FRAMES) {
                        Err("Illegal number of frame buffers; use a number between 2 and %d.\n", MAX_FRAMES);
                        return -EINVAL;
                }
                default_fbufs = fbufs;
                Info("Number of frame buffers set to %d.\n", default_fbufs);
        }
        if (trace >= 0) {
                Info("Trace options: 0x%04x\n", trace);
                pwc_trace = trace;
        }
        if (compression >= 0) {
                if (compression > 3) {
                        Err("Invalid compression setting; use a number between 0 (uncompressed) and 3 (high).\n");
                        return -EINVAL;
                }
                pwc_preferred_compression = compression;
                Info("Preferred compression set to %d.\n", pwc_preferred_compression);
        }
        if (power_save)
                Info("Enabling power save on open/close.\n");
        if (leds[0] >= 0)
                led_on = leds[0];
        if (leds[1] >= 0)
                led_off = leds[1];

        /* Big device node whoopla. Basicly, it allows you to assign a 
           device node (/dev/videoX) to a camera, based on its type 
           & serial number. The format is [type[.serialnumber]:]node.

           Any camera that isn't matched by these rules gets the next 
           available free device node.
         */
        for (i = 0; i < MAX_DEV_HINTS; i++) {
                char *s, *colon, *dot;

                /* This loop also initializes the array */
                device_hint[i].pdev = NULL;
                s = dev_hint[i];
                if (s != NULL && *s != '\0') {
                        device_hint[i].type = -1; /* wildcard */
                        strcpy(device_hint[i].serial_number, "*");

                        /* parse string: chop at ':' & '/' */
                        colon = dot = s;
                        while (*colon != '\0' && *colon != ':')
                                colon++;
                        while (*dot != '\0' && *dot != '.')
                                dot++;
                        /* Few sanity checks */
                        if (*dot != '\0' && dot > colon) {
                                Err("Malformed camera hint: the colon must be after the dot.\n");
                                return -EINVAL;
                        }

                        if (*colon == '\0') {
                                /* No colon */
                                if (*dot != '\0') {
                                        Err("Malformed camera hint: no colon + device node given.\n");
                                        return -EINVAL;
                                }
                                else {
                                        /* No type or serial number specified, just a number. */
                                        device_hint[i].device_node = pwc_atoi(s);
                                }
                        }
                        else {
                                /* There's a colon, so we have at least a type and a device node */
                                device_hint[i].type = pwc_atoi(s);
                                device_hint[i].device_node = pwc_atoi(colon + 1);
                                if (*dot != '\0') {
                                        /* There's a serial number as well */
                                        int k;
                                        
                                        dot++;
                                        k = 0;
                                        while (*dot != ':' && k < 29) {
                                                device_hint[i].serial_number[k++] = *dot;
                                                dot++;
                                        }
                                        device_hint[i].serial_number[k] = '\0';
                                }
                        }
#if PWC_DEBUG           
                        Debug("device_hint[%d]:\n", i);
                        Debug("  type    : %d\n", device_hint[i].type);
                        Debug("  serial# : %s\n", device_hint[i].serial_number);
                        Debug("  node    : %d\n", device_hint[i].device_node);
#endif                  
                }
                else
                        device_hint[i].type = 0; /* not filled */
        } /* ..for MAX_DEV_HINTS */

        Trace(TRACE_PROBE, "Registering driver at address 0x%p.\n", &pwc_driver);
        return usb_register(&pwc_driver);
}

static void __exit usb_pwc_exit(void)
{
        Trace(TRACE_MODULE, "Deregistering driver.\n");
        usb_deregister(&pwc_driver);
        Info("Philips webcam module removed.\n");
}

module_init(usb_pwc_init);
module_exit(usb_pwc_exit);