Linux-2.6.12-rc2

[mirror_ubuntu-bionic-kernel.git] / drivers / usb / media / usbvideo.c

/*
 * 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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/spinlock.h>

#include <asm/io.h>

#include "usbvideo.h"

#if defined(MAP_NR)
#define virt_to_page(v) MAP_NR(v)       /* Kernels 2.2.x */
#endif

static int video_nr = -1;
module_param(video_nr, int, 0);

/*
 * Local prototypes.
 */
static void usbvideo_Disconnect(struct usb_interface *intf);
static void usbvideo_CameraRelease(struct uvd *uvd);

static int usbvideo_v4l_ioctl(struct inode *inode, struct file *file,
                              unsigned int cmd, unsigned long arg);
static int usbvideo_v4l_mmap(struct file *file, struct vm_area_struct *vma);
static int usbvideo_v4l_open(struct inode *inode, struct file *file);
static ssize_t usbvideo_v4l_read(struct file *file, char __user *buf,
                             size_t count, loff_t *ppos);
static int usbvideo_v4l_close(struct inode *inode, struct file *file);

static int usbvideo_StartDataPump(struct uvd *uvd);
static void usbvideo_StopDataPump(struct uvd *uvd);
static int usbvideo_GetFrame(struct uvd *uvd, int frameNum);
static int usbvideo_NewFrame(struct uvd *uvd, int framenum);
static void usbvideo_SoftwareContrastAdjustment(struct uvd *uvd,
                                                struct usbvideo_frame *frame);

/*******************************/
/* Memory management functions */
/*******************************/
static void *usbvideo_rvmalloc(unsigned long size)
{
        void *mem;
        unsigned long adr;

        size = PAGE_ALIGN(size);
        mem = vmalloc_32(size);
        if (!mem)
                return NULL;

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

        return mem;
}

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

        if (!mem)
                return;

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

static void RingQueue_Initialize(struct RingQueue *rq)
{
        assert(rq != NULL);
        init_waitqueue_head(&rq->wqh);
}

static void RingQueue_Allocate(struct RingQueue *rq, int rqLen)
{
        /* Make sure the requested size is a power of 2 and
           round up if necessary. This allows index wrapping
           using masks rather than modulo */

        int i = 1;
        assert(rq != NULL);
        assert(rqLen > 0);

        while(rqLen >> i)
                i++;
        if(rqLen != 1 << (i-1))
                rqLen = 1 << i;

        rq->length = rqLen;
        rq->ri = rq->wi = 0;
        rq->queue = usbvideo_rvmalloc(rq->length);
        assert(rq->queue != NULL);
}

static int RingQueue_IsAllocated(const struct RingQueue *rq)
{
        if (rq == NULL)
                return 0;
        return (rq->queue != NULL) && (rq->length > 0);
}

static void RingQueue_Free(struct RingQueue *rq)
{
        assert(rq != NULL);
        if (RingQueue_IsAllocated(rq)) {
                usbvideo_rvfree(rq->queue, rq->length);
                rq->queue = NULL;
                rq->length = 0;
        }
}

int RingQueue_Dequeue(struct RingQueue *rq, unsigned char *dst, int len)
{
        int rql, toread;

        assert(rq != NULL);
        assert(dst != NULL);

        rql = RingQueue_GetLength(rq);
        if(!rql)
                return 0;

        /* Clip requested length to available data */
        if(len > rql)
                len = rql;

        toread = len;
        if(rq->ri > rq->wi) {
                /* Read data from tail */
                int read = (toread < (rq->length - rq->ri)) ? toread : rq->length - rq->ri;
                memcpy(dst, rq->queue + rq->ri, read);
                toread -= read;
                dst += read;
                rq->ri = (rq->ri + read) & (rq->length-1);
        }
        if(toread) {
                /* Read data from head */
                memcpy(dst, rq->queue + rq->ri, toread);
                rq->ri = (rq->ri + toread) & (rq->length-1);
        }
        return len;
}

EXPORT_SYMBOL(RingQueue_Dequeue);

int RingQueue_Enqueue(struct RingQueue *rq, const unsigned char *cdata, int n)
{
        int enqueued = 0;

        assert(rq != NULL);
        assert(cdata != NULL);
        assert(rq->length > 0);
        while (n > 0) {
                int m, q_avail;

                /* Calculate the largest chunk that fits the tail of the ring */
                q_avail = rq->length - rq->wi;
                if (q_avail <= 0) {
                        rq->wi = 0;
                        q_avail = rq->length;
                }
                m = n;
                assert(q_avail > 0);
                if (m > q_avail)
                        m = q_avail;

                memcpy(rq->queue + rq->wi, cdata, m);
                RING_QUEUE_ADVANCE_INDEX(rq, wi, m);
                cdata += m;
                enqueued += m;
                n -= m;
        }
        return enqueued;
}

EXPORT_SYMBOL(RingQueue_Enqueue);

static void RingQueue_InterruptibleSleepOn(struct RingQueue *rq)
{
        assert(rq != NULL);
        interruptible_sleep_on(&rq->wqh);
}

void RingQueue_WakeUpInterruptible(struct RingQueue *rq)
{
        assert(rq != NULL);
        if (waitqueue_active(&rq->wqh))
                wake_up_interruptible(&rq->wqh);
}

EXPORT_SYMBOL(RingQueue_WakeUpInterruptible);

void RingQueue_Flush(struct RingQueue *rq)
{
        assert(rq != NULL);
        rq->ri = 0;
        rq->wi = 0;
}

EXPORT_SYMBOL(RingQueue_Flush);


/*
 * usbvideo_VideosizeToString()
 *
 * This procedure converts given videosize value to readable string.
 *
 * History:
 * 07-Aug-2000 Created.
 * 19-Oct-2000 Reworked for usbvideo module.
 */
static void usbvideo_VideosizeToString(char *buf, int bufLen, videosize_t vs)
{
        char tmp[40];
        int n;

        n = 1 + sprintf(tmp, "%ldx%ld", VIDEOSIZE_X(vs), VIDEOSIZE_Y(vs));
        assert(n < sizeof(tmp));
        if ((buf == NULL) || (bufLen < n))
                err("usbvideo_VideosizeToString: buffer is too small.");
        else
                memmove(buf, tmp, n);
}

/*
 * usbvideo_OverlayChar()
 *
 * History:
 * 01-Feb-2000 Created.
 */
static void usbvideo_OverlayChar(struct uvd *uvd, struct usbvideo_frame *frame,
                                 int x, int y, int ch)
{
        static const unsigned short digits[16] = {
                0xF6DE, /* 0 */
                0x2492, /* 1 */
                0xE7CE, /* 2 */
                0xE79E, /* 3 */
                0xB792, /* 4 */
                0xF39E, /* 5 */
                0xF3DE, /* 6 */
                0xF492, /* 7 */
                0xF7DE, /* 8 */
                0xF79E, /* 9 */
                0x77DA, /* a */
                0xD75C, /* b */
                0xF24E, /* c */
                0xD6DC, /* d */
                0xF34E, /* e */
                0xF348  /* f */
        };
        unsigned short digit;
        int ix, iy;

        if ((uvd == NULL) || (frame == NULL))
                return;

        if (ch >= '0' && ch <= '9')
                ch -= '0';
        else if (ch >= 'A' && ch <= 'F')
                ch = 10 + (ch - 'A');
        else if (ch >= 'a' && ch <= 'f')
                ch = 10 + (ch - 'a');
        else
                return;
        digit = digits[ch];

        for (iy=0; iy < 5; iy++) {
                for (ix=0; ix < 3; ix++) {
                        if (digit & 0x8000) {
                                if (uvd->paletteBits & (1L << VIDEO_PALETTE_RGB24)) {
/* TODO */                              RGB24_PUTPIXEL(frame, x+ix, y+iy, 0xFF, 0xFF, 0xFF);
                                }
                        }
                        digit = digit << 1;
                }
        }
}

/*
 * usbvideo_OverlayString()
 *
 * History:
 * 01-Feb-2000 Created.
 */
static void usbvideo_OverlayString(struct uvd *uvd, struct usbvideo_frame *frame,
                                   int x, int y, const char *str)
{
        while (*str) {
                usbvideo_OverlayChar(uvd, frame, x, y, *str);
                str++;
                x += 4; /* 3 pixels character + 1 space */
        }
}

/*
 * usbvideo_OverlayStats()
 *
 * Overlays important debugging information.
 *
 * History:
 * 01-Feb-2000 Created.
 */
static void usbvideo_OverlayStats(struct uvd *uvd, struct usbvideo_frame *frame)
{
        const int y_diff = 8;
        char tmp[16];
        int x = 10, y=10;
        long i, j, barLength;
        const int qi_x1 = 60, qi_y1 = 10;
        const int qi_x2 = VIDEOSIZE_X(frame->request) - 10, qi_h = 10;

        /* Call the user callback, see if we may proceed after that */
        if (VALID_CALLBACK(uvd, overlayHook)) {
                if (GET_CALLBACK(uvd, overlayHook)(uvd, frame) < 0)
                        return;
        }

        /*
         * We draw a (mostly) hollow rectangle with qi_xxx coordinates.
         * Left edge symbolizes the queue index 0; right edge symbolizes
         * the full capacity of the queue.
         */
        barLength = qi_x2 - qi_x1 - 2;
        if ((barLength > 10) && (uvd->paletteBits & (1L << VIDEO_PALETTE_RGB24))) {
/* TODO */      long u_lo, u_hi, q_used;
                long m_ri, m_wi, m_lo, m_hi;

                /*
                 * Determine fill zones (used areas of the queue):
                 * 0 xxxxxxx u_lo ...... uvd->dp.ri xxxxxxxx u_hi ..... uvd->dp.length
                 *
                 * if u_lo < 0 then there is no first filler.
                 */

                q_used = RingQueue_GetLength(&uvd->dp);
                if ((uvd->dp.ri + q_used) >= uvd->dp.length) {
                        u_hi = uvd->dp.length;
                        u_lo = (q_used + uvd->dp.ri) & (uvd->dp.length-1);
                } else {
                        u_hi = (q_used + uvd->dp.ri);
                        u_lo = -1;
                }

                /* Convert byte indices into screen units */
                m_ri = qi_x1 + ((barLength * uvd->dp.ri) / uvd->dp.length);
                m_wi = qi_x1 + ((barLength * uvd->dp.wi) / uvd->dp.length);
                m_lo = (u_lo > 0) ? (qi_x1 + ((barLength * u_lo) / uvd->dp.length)) : -1;
                m_hi = qi_x1 + ((barLength * u_hi) / uvd->dp.length);

                for (j=qi_y1; j < (qi_y1 + qi_h); j++) {
                        for (i=qi_x1; i < qi_x2; i++) {
                                /* Draw border lines */
                                if ((j == qi_y1) || (j == (qi_y1 + qi_h - 1)) ||
                                    (i == qi_x1) || (i == (qi_x2 - 1))) {
                                        RGB24_PUTPIXEL(frame, i, j, 0xFF, 0xFF, 0xFF);
                                        continue;
                                }
                                /* For all other points the Y coordinate does not matter */
                                if ((i >= m_ri) && (i <= (m_ri + 3))) {
                                        RGB24_PUTPIXEL(frame, i, j, 0x00, 0xFF, 0x00);
                                } else if ((i >= m_wi) && (i <= (m_wi + 3))) {
                                        RGB24_PUTPIXEL(frame, i, j, 0xFF, 0x00, 0x00);
                                } else if ((i < m_lo) || ((i > m_ri) && (i < m_hi)))
                                        RGB24_PUTPIXEL(frame, i, j, 0x00, 0x00, 0xFF);
                        }
                }
        }

        sprintf(tmp, "%8lx", uvd->stats.frame_num);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8lx", uvd->stats.urb_count);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8lx", uvd->stats.urb_length);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8lx", uvd->stats.data_count);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8lx", uvd->stats.header_count);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8lx", uvd->stats.iso_skip_count);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8lx", uvd->stats.iso_err_count);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8x", uvd->vpic.colour);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8x", uvd->vpic.hue);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8x", uvd->vpic.brightness >> 8);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8x", uvd->vpic.contrast >> 12);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;

        sprintf(tmp, "%8d", uvd->vpic.whiteness >> 8);
        usbvideo_OverlayString(uvd, frame, x, y, tmp);
        y += y_diff;
}

/*
 * usbvideo_ReportStatistics()
 *
 * This procedure prints packet and transfer statistics.
 *
 * History:
 * 14-Jan-2000 Corrected default multiplier.
 */
static void usbvideo_ReportStatistics(const struct uvd *uvd)
{
        if ((uvd != NULL) && (uvd->stats.urb_count > 0)) {
                unsigned long allPackets, badPackets, goodPackets, percent;
                allPackets = uvd->stats.urb_count * CAMERA_URB_FRAMES;
                badPackets = uvd->stats.iso_skip_count + uvd->stats.iso_err_count;
                goodPackets = allPackets - badPackets;
                /* Calculate percentage wisely, remember integer limits */
                assert(allPackets != 0);
                if (goodPackets < (((unsigned long)-1)/100))
                        percent = (100 * goodPackets) / allPackets;
                else
                        percent = goodPackets / (allPackets / 100);
                info("Packet Statistics: Total=%lu. Empty=%lu. Usage=%lu%%",
                     allPackets, badPackets, percent);
                if (uvd->iso_packet_len > 0) {
                        unsigned long allBytes, xferBytes;
                        char multiplier = ' ';
                        allBytes = allPackets * uvd->iso_packet_len;
                        xferBytes = uvd->stats.data_count;
                        assert(allBytes != 0);
                        if (xferBytes < (((unsigned long)-1)/100))
                                percent = (100 * xferBytes) / allBytes;
                        else
                                percent = xferBytes / (allBytes / 100);
                        /* Scale xferBytes for easy reading */
                        if (xferBytes > 10*1024) {
                                xferBytes /= 1024;
                                multiplier = 'K';
                                if (xferBytes > 10*1024) {
                                        xferBytes /= 1024;
                                        multiplier = 'M';
                                        if (xferBytes > 10*1024) {
                                                xferBytes /= 1024;
                                                multiplier = 'G';
                                                if (xferBytes > 10*1024) {
                                                        xferBytes /= 1024;
                                                        multiplier = 'T';
                                                }
                                        }
                                }
                        }
                        info("Transfer Statistics: Transferred=%lu%cB Usage=%lu%%",
                             xferBytes, multiplier, percent);
                }
        }
}

/*
 * usbvideo_TestPattern()
 *
 * Procedure forms a test pattern (yellow grid on blue background).
 *
 * Parameters:
 * fullframe: if TRUE then entire frame is filled, otherwise the procedure
 *            continues from the current scanline.
 * pmode      0: fill the frame with solid blue color (like on VCR or TV)
 *            1: Draw a colored grid
 *
 * History:
 * 01-Feb-2000 Created.
 */
void usbvideo_TestPattern(struct uvd *uvd, int fullframe, int pmode)
{
        struct usbvideo_frame *frame;
        int num_cell = 0;
        int scan_length = 0;
        static int num_pass = 0;

        if (uvd == NULL) {
                err("%s: uvd == NULL", __FUNCTION__);
                return;
        }
        if ((uvd->curframe < 0) || (uvd->curframe >= USBVIDEO_NUMFRAMES)) {
                err("%s: uvd->curframe=%d.", __FUNCTION__, uvd->curframe);
                return;
        }

        /* Grab the current frame */
        frame = &uvd->frame[uvd->curframe];

        /* Optionally start at the beginning */
        if (fullframe) {
                frame->curline = 0;
                frame->seqRead_Length = 0;
        }
#if 0
        {       /* For debugging purposes only */
                char tmp[20];
                usbvideo_VideosizeToString(tmp, sizeof(tmp), frame->request);
                info("testpattern: frame=%s", tmp);
        }
#endif
        /* Form every scan line */
        for (; frame->curline < VIDEOSIZE_Y(frame->request); frame->curline++) {
                int i;
                unsigned char *f = frame->data +
                        (VIDEOSIZE_X(frame->request) * V4L_BYTES_PER_PIXEL * frame->curline);
                for (i=0; i < VIDEOSIZE_X(frame->request); i++) {
                        unsigned char cb=0x80;
                        unsigned char cg = 0;
                        unsigned char cr = 0;

                        if (pmode == 1) {
                                if (frame->curline % 32 == 0)
                                        cb = 0, cg = cr = 0xFF;
                                else if (i % 32 == 0) {
                                        if (frame->curline % 32 == 1)
                                                num_cell++;
                                        cb = 0, cg = cr = 0xFF;
                                } else {
                                        cb = ((num_cell*7) + num_pass) & 0xFF;
                                        cg = ((num_cell*5) + num_pass*2) & 0xFF;
                                        cr = ((num_cell*3) + num_pass*3) & 0xFF;
                                }
                        } else {
                                /* Just the blue screen */
                        }
                                
                        *f++ = cb;
                        *f++ = cg;
                        *f++ = cr;
                        scan_length += 3;
                }
        }

        frame->frameState = FrameState_Done;
        frame->seqRead_Length += scan_length;
        ++num_pass;

        /* We do this unconditionally, regardless of FLAGS_OVERLAY_STATS */
        usbvideo_OverlayStats(uvd, frame);
}

EXPORT_SYMBOL(usbvideo_TestPattern);


#ifdef DEBUG
/*
 * usbvideo_HexDump()
 *
 * A debugging tool. Prints hex dumps.
 *
 * History:
 * 29-Jul-2000 Added printing of offsets.
 */
void usbvideo_HexDump(const unsigned char *data, int len)
{
        const int bytes_per_line = 32;
        char tmp[128]; /* 32*3 + 5 */
        int i, k;

        for (i=k=0; len > 0; i++, len--) {
                if (i > 0 && ((i % bytes_per_line) == 0)) {
                        printk("%s\n", tmp);
                        k=0;
                }
                if ((i % bytes_per_line) == 0)
                        k += sprintf(&tmp[k], "%04x: ", i);
                k += sprintf(&tmp[k], "%02x ", data[i]);
        }
        if (k > 0)
                printk("%s\n", tmp);
}

EXPORT_SYMBOL(usbvideo_HexDump);

#endif

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

/* XXX: this piece of crap really wants some error handling.. */
static void usbvideo_ClientIncModCount(struct uvd *uvd)
{
        if (uvd == NULL) {
                err("%s: uvd == NULL", __FUNCTION__);
                return;
        }
        if (uvd->handle == NULL) {
                err("%s: uvd->handle == NULL", __FUNCTION__);
                return;
        }
        if (uvd->handle->md_module == NULL) {
                err("%s: uvd->handle->md_module == NULL", __FUNCTION__);
                return;
        }
        if (!try_module_get(uvd->handle->md_module)) {
                err("%s: try_module_get() == 0", __FUNCTION__);
                return;
        }
}

static void usbvideo_ClientDecModCount(struct uvd *uvd)
{
        if (uvd == NULL) {
                err("%s: uvd == NULL", __FUNCTION__);
                return;
        }
        if (uvd->handle == NULL) {
                err("%s: uvd->handle == NULL", __FUNCTION__);
                return;
        }
        if (uvd->handle->md_module == NULL) {
                err("%s: uvd->handle->md_module == NULL", __FUNCTION__);
                return;
        }
        module_put(uvd->handle->md_module);
}

int usbvideo_register(
        struct usbvideo **pCams,
        const int num_cams,
        const int num_extra,
        const char *driverName,
        const struct usbvideo_cb *cbTbl,
        struct module *md,
        const struct usb_device_id *id_table)
{
        struct usbvideo *cams;
        int i, base_size, result;

        /* Check parameters for sanity */
        if ((num_cams <= 0) || (pCams == NULL) || (cbTbl == NULL)) {
                err("%s: Illegal call", __FUNCTION__);
                return -EINVAL;
        }

        /* Check registration callback - must be set! */
        if (cbTbl->probe == NULL) {
                err("%s: probe() is required!", __FUNCTION__);
                return -EINVAL;
        }

        base_size = num_cams * sizeof(struct uvd) + sizeof(struct usbvideo);
        cams = (struct usbvideo *) kmalloc(base_size, GFP_KERNEL);
        if (cams == NULL) {
                err("Failed to allocate %d. bytes for usbvideo struct", base_size);
                return -ENOMEM;
        }
        dbg("%s: Allocated $%p (%d. bytes) for %d. cameras",
            __FUNCTION__, cams, base_size, num_cams);
        memset(cams, 0, base_size);

        /* Copy callbacks, apply defaults for those that are not set */
        memmove(&cams->cb, cbTbl, sizeof(cams->cb));
        if (cams->cb.getFrame == NULL)
                cams->cb.getFrame = usbvideo_GetFrame;
        if (cams->cb.disconnect == NULL)
                cams->cb.disconnect = usbvideo_Disconnect;
        if (cams->cb.startDataPump == NULL)
                cams->cb.startDataPump = usbvideo_StartDataPump;
        if (cams->cb.stopDataPump == NULL)
                cams->cb.stopDataPump = usbvideo_StopDataPump;

        cams->num_cameras = num_cams;
        cams->cam = (struct uvd *) &cams[1];
        cams->md_module = md;
        if (cams->md_module == NULL)
                warn("%s: module == NULL!", __FUNCTION__);
        init_MUTEX(&cams->lock);        /* to 1 == available */

        for (i = 0; i < num_cams; i++) {
                struct uvd *up = &cams->cam[i];

                up->handle = cams;

                /* Allocate user_data separately because of kmalloc's limits */
                if (num_extra > 0) {
                        up->user_size = num_cams * num_extra;
                        up->user_data = (char *) kmalloc(up->user_size, GFP_KERNEL);
                        if (up->user_data == NULL) {
                                err("%s: Failed to allocate user_data (%d. bytes)",
                                    __FUNCTION__, up->user_size);
                                while (i) {
                                        up = &cams->cam[--i];
                                        kfree(up->user_data);
                                }
                                kfree(cams);
                                return -ENOMEM;
                        }
                        dbg("%s: Allocated cams[%d].user_data=$%p (%d. bytes)",
                             __FUNCTION__, i, up->user_data, up->user_size);
                }
        }

        /*
         * Register ourselves with USB stack.
         */
        strcpy(cams->drvName, (driverName != NULL) ? driverName : "Unknown");
        cams->usbdrv.name = cams->drvName;
        cams->usbdrv.probe = cams->cb.probe;
        cams->usbdrv.disconnect = cams->cb.disconnect;
        cams->usbdrv.id_table = id_table;

        /*
         * Update global handle to usbvideo. This is very important
         * because probe() can be called before usb_register() returns.
         * If the handle is not yet updated then the probe() will fail.
         */
        *pCams = cams;
        result = usb_register(&cams->usbdrv);
        if (result) {
                for (i = 0; i < num_cams; i++) {
                        struct uvd *up = &cams->cam[i];
                        kfree(up->user_data);
                }
                kfree(cams);
        }

        return result;
}

EXPORT_SYMBOL(usbvideo_register);

/*
 * usbvideo_Deregister()
 *
 * Procedure frees all usbvideo and user data structures. Be warned that
 * if you had some dynamically allocated components in ->user field then
 * you should free them before calling here.
 */
void usbvideo_Deregister(struct usbvideo **pCams)
{
        struct usbvideo *cams;
        int i;

        if (pCams == NULL) {
                err("%s: pCams == NULL", __FUNCTION__);
                return;
        }
        cams = *pCams;
        if (cams == NULL) {
                err("%s: cams == NULL", __FUNCTION__);
                return;
        }

        dbg("%s: Deregistering %s driver.", __FUNCTION__, cams->drvName);
        usb_deregister(&cams->usbdrv);

        dbg("%s: Deallocating cams=$%p (%d. cameras)", __FUNCTION__, cams, cams->num_cameras);
        for (i=0; i < cams->num_cameras; i++) {
                struct uvd *up = &cams->cam[i];
                int warning = 0;

                if (up->user_data != NULL) {
                        if (up->user_size <= 0)
                                ++warning;
                } else {
                        if (up->user_size > 0)
                                ++warning;
                }
                if (warning) {
                        err("%s: Warning: user_data=$%p user_size=%d.",
                            __FUNCTION__, up->user_data, up->user_size);
                } else {
                        dbg("%s: Freeing %d. $%p->user_data=$%p",
                            __FUNCTION__, i, up, up->user_data);
                        kfree(up->user_data);
                }
        }
        /* Whole array was allocated in one chunk */
        dbg("%s: Freed %d uvd structures",
            __FUNCTION__, cams->num_cameras);
        kfree(cams);
        *pCams = NULL;
}

EXPORT_SYMBOL(usbvideo_Deregister);

/*
 * usbvideo_Disconnect()
 *
 * This procedure stops all driver activity. Deallocation of
 * the interface-private structure (pointed by 'ptr') is done now
 * (if we don't have any open files) or later, when those files
 * are closed. After that driver should be removable.
 *
 * This code handles surprise removal. The uvd->user is a counter which
 * increments on open() and decrements on close(). If we see here that
 * this counter is not 0 then we have a client who still has us opened.
 * We set uvd->remove_pending flag as early as possible, and after that
 * all access to the camera will gracefully fail. These failures should
 * prompt client to (eventually) close the video device, and then - in
 * usbvideo_v4l_close() - we decrement uvd->uvd_used and usage counter.
 *
 * History:
 * 22-Jan-2000 Added polling of MOD_IN_USE to delay removal until all users gone.
 * 27-Jan-2000 Reworked to allow pending disconnects; see xxx_close()
 * 24-May-2000 Corrected to prevent race condition (MOD_xxx_USE_COUNT).
 * 19-Oct-2000 Moved to usbvideo module.
 */
static void usbvideo_Disconnect(struct usb_interface *intf)
{
        struct uvd *uvd = usb_get_intfdata (intf);
        int i;

        if (uvd == NULL) {
                err("%s($%p): Illegal call.", __FUNCTION__, intf);
                return;
        }

        usb_set_intfdata (intf, NULL);

        usbvideo_ClientIncModCount(uvd);
        if (uvd->debug > 0)
                info("%s(%p.)", __FUNCTION__, intf);

        down(&uvd->lock);
        uvd->remove_pending = 1; /* Now all ISO data will be ignored */

        /* At this time we ask to cancel outstanding URBs */
        GET_CALLBACK(uvd, stopDataPump)(uvd);

        for (i=0; i < USBVIDEO_NUMSBUF; i++)
                usb_free_urb(uvd->sbuf[i].urb);

        usb_put_dev(uvd->dev);
        uvd->dev = NULL;            /* USB device is no more */

        video_unregister_device(&uvd->vdev);
        if (uvd->debug > 0)
                info("%s: Video unregistered.", __FUNCTION__);

        if (uvd->user)
                info("%s: In use, disconnect pending.", __FUNCTION__);
        else
                usbvideo_CameraRelease(uvd);
        up(&uvd->lock);
        info("USB camera disconnected.");

        usbvideo_ClientDecModCount(uvd);
}

/*
 * usbvideo_CameraRelease()
 *
 * This code does final release of uvd. This happens
 * after the device is disconnected -and- all clients
 * closed their files.
 *
 * History:
 * 27-Jan-2000 Created.
 */
static void usbvideo_CameraRelease(struct uvd *uvd)
{
        if (uvd == NULL) {
                err("%s: Illegal call", __FUNCTION__);
                return;
        }

        RingQueue_Free(&uvd->dp);
        if (VALID_CALLBACK(uvd, userFree))
                GET_CALLBACK(uvd, userFree)(uvd);
        uvd->uvd_used = 0;      /* This is atomic, no need to take mutex */
}

/*
 * usbvideo_find_struct()
 *
 * This code searches the array of preallocated (static) structures
 * and returns index of the first one that isn't in use. Returns -1
 * if there are no free structures.
 *
 * History:
 * 27-Jan-2000 Created.
 */
static int usbvideo_find_struct(struct usbvideo *cams)
{
        int u, rv = -1;

        if (cams == NULL) {
                err("No usbvideo handle?");
                return -1;
        }
        down(&cams->lock);
        for (u = 0; u < cams->num_cameras; u++) {
                struct uvd *uvd = &cams->cam[u];
                if (!uvd->uvd_used) /* This one is free */
                {
                        uvd->uvd_used = 1;      /* In use now */
                        init_MUTEX(&uvd->lock); /* to 1 == available */
                        uvd->dev = NULL;
                        rv = u;
                        break;
                }
        }
        up(&cams->lock);
        return rv;
}

static struct file_operations usbvideo_fops = {
        .owner =  THIS_MODULE,
        .open =   usbvideo_v4l_open,
        .release =usbvideo_v4l_close,
        .read =   usbvideo_v4l_read,
        .mmap =   usbvideo_v4l_mmap,
        .ioctl =  usbvideo_v4l_ioctl,
        .llseek = no_llseek,
};
static struct video_device usbvideo_template = {
        .owner =      THIS_MODULE,
        .type =       VID_TYPE_CAPTURE,
        .hardware =   VID_HARDWARE_CPIA,
        .fops =       &usbvideo_fops,
};

struct uvd *usbvideo_AllocateDevice(struct usbvideo *cams)
{
        int i, devnum;
        struct uvd *uvd = NULL;

        if (cams == NULL) {
                err("No usbvideo handle?");
                return NULL;
        }

        devnum = usbvideo_find_struct(cams);
        if (devnum == -1) {
                err("IBM USB camera driver: Too many devices!");
                return NULL;
        }
        uvd = &cams->cam[devnum];
        dbg("Device entry #%d. at $%p", devnum, uvd);

        /* Not relying upon caller we increase module counter ourselves */
        usbvideo_ClientIncModCount(uvd);

        down(&uvd->lock);
        for (i=0; i < USBVIDEO_NUMSBUF; i++) {
                uvd->sbuf[i].urb = usb_alloc_urb(FRAMES_PER_DESC, GFP_KERNEL);
                if (uvd->sbuf[i].urb == NULL) {
                        err("usb_alloc_urb(%d.) failed.", FRAMES_PER_DESC);
                        uvd->uvd_used = 0;
                        uvd = NULL;
                        goto allocate_done;
                }
        }
        uvd->user=0;
        uvd->remove_pending = 0;
        uvd->last_error = 0;
        RingQueue_Initialize(&uvd->dp);

        /* Initialize video device structure */
        uvd->vdev = usbvideo_template;
        sprintf(uvd->vdev.name, "%.20s USB Camera", cams->drvName);
        /*
         * The client is free to overwrite those because we
         * return control to the client's probe function right now.
         */
allocate_done:
        up (&uvd->lock);
        usbvideo_ClientDecModCount(uvd);
        return uvd;
}

EXPORT_SYMBOL(usbvideo_AllocateDevice);

int usbvideo_RegisterVideoDevice(struct uvd *uvd)
{
        char tmp1[20], tmp2[20];        /* Buffers for printing */

        if (uvd == NULL) {
                err("%s: Illegal call.", __FUNCTION__);
                return -EINVAL;
        }
        if (uvd->video_endp == 0) {
                info("%s: No video endpoint specified; data pump disabled.", __FUNCTION__);
        }
        if (uvd->paletteBits == 0) {
                err("%s: No palettes specified!", __FUNCTION__);
                return -EINVAL;
        }
        if (uvd->defaultPalette == 0) {
                info("%s: No default palette!", __FUNCTION__);
        }

        uvd->max_frame_size = VIDEOSIZE_X(uvd->canvas) *
                VIDEOSIZE_Y(uvd->canvas) * V4L_BYTES_PER_PIXEL;
        usbvideo_VideosizeToString(tmp1, sizeof(tmp1), uvd->videosize);
        usbvideo_VideosizeToString(tmp2, sizeof(tmp2), uvd->canvas);

        if (uvd->debug > 0) {
                info("%s: iface=%d. endpoint=$%02x paletteBits=$%08lx",
                     __FUNCTION__, uvd->iface, uvd->video_endp, uvd->paletteBits);
        }
        if (video_register_device(&uvd->vdev, VFL_TYPE_GRABBER, video_nr) == -1) {
                err("%s: video_register_device failed", __FUNCTION__);
                return -EPIPE;
        }
        if (uvd->debug > 1) {
                info("%s: video_register_device() successful", __FUNCTION__);
        }
        if (uvd->dev == NULL) {
                err("%s: uvd->dev == NULL", __FUNCTION__);
                return -EINVAL;
        }

        info("%s on /dev/video%d: canvas=%s videosize=%s",
             (uvd->handle != NULL) ? uvd->handle->drvName : "???",
             uvd->vdev.minor, tmp2, tmp1);

        usb_get_dev(uvd->dev);
        return 0;
}

EXPORT_SYMBOL(usbvideo_RegisterVideoDevice);

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

static int usbvideo_v4l_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct uvd *uvd = file->private_data;
        unsigned long start = vma->vm_start;
        unsigned long size  = vma->vm_end-vma->vm_start;
        unsigned long page, pos;

        if (!CAMERA_IS_OPERATIONAL(uvd))
                return -EFAULT;

        if (size > (((USBVIDEO_NUMFRAMES * uvd->max_frame_size) + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1)))
                return -EINVAL;

        pos = (unsigned long) uvd->fbuf;
        while (size > 0) {
                page = vmalloc_to_pfn((void *)pos);
                if (remap_pfn_range(vma, 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;
}

/*
 * usbvideo_v4l_open()
 *
 * This is part of Video 4 Linux API. The driver can be opened by one
 * client only (checks internal counter 'uvdser'). The procedure
 * then allocates buffers needed for video processing.
 *
 * History:
 * 22-Jan-2000 Rewrote, moved scratch buffer allocation here. Now the
 *             camera is also initialized here (once per connect), at
 *             expense of V4L client (it waits on open() call).
 * 27-Jan-2000 Used USBVIDEO_NUMSBUF as number of URB buffers.
 * 24-May-2000 Corrected to prevent race condition (MOD_xxx_USE_COUNT).
 */
static int usbvideo_v4l_open(struct inode *inode, struct file *file)
{
        struct video_device *dev = video_devdata(file);
        struct uvd *uvd = (struct uvd *) dev;
        const int sb_size = FRAMES_PER_DESC * uvd->iso_packet_len;
        int i, errCode = 0;

        if (uvd->debug > 1)
                info("%s($%p)", __FUNCTION__, dev);

        usbvideo_ClientIncModCount(uvd);
        down(&uvd->lock);

        if (uvd->user) {
                err("%s: Someone tried to open an already opened device!", __FUNCTION__);
                errCode = -EBUSY;
        } else {
                /* Clear statistics */
                memset(&uvd->stats, 0, sizeof(uvd->stats));

                /* Clean pointers so we know if we allocated something */
                for (i=0; i < USBVIDEO_NUMSBUF; i++)
                        uvd->sbuf[i].data = NULL;

                /* Allocate memory for the frame buffers */
                uvd->fbuf_size = USBVIDEO_NUMFRAMES * uvd->max_frame_size;
                uvd->fbuf = usbvideo_rvmalloc(uvd->fbuf_size);
                RingQueue_Allocate(&uvd->dp, RING_QUEUE_SIZE);
                if ((uvd->fbuf == NULL) ||
                    (!RingQueue_IsAllocated(&uvd->dp))) {
                        err("%s: Failed to allocate fbuf or dp", __FUNCTION__);
                        errCode = -ENOMEM;
                } else {
                        /* Allocate all buffers */
                        for (i=0; i < USBVIDEO_NUMFRAMES; i++) {
                                uvd->frame[i].frameState = FrameState_Unused;
                                uvd->frame[i].data = uvd->fbuf + i*(uvd->max_frame_size);
                                /*
                                 * Set default sizes in case IOCTL (VIDIOCMCAPTURE)
                                 * is not used (using read() instead).
                                 */
                                uvd->frame[i].canvas = uvd->canvas;
                                uvd->frame[i].seqRead_Index = 0;
                        }
                        for (i=0; i < USBVIDEO_NUMSBUF; i++) {
                                uvd->sbuf[i].data = kmalloc(sb_size, GFP_KERNEL);
                                if (uvd->sbuf[i].data == NULL) {
                                        errCode = -ENOMEM;
                                        break;
                                }
                        }
                }
                if (errCode != 0) {
                        /* Have to free all that memory */
                        if (uvd->fbuf != NULL) {
                                usbvideo_rvfree(uvd->fbuf, uvd->fbuf_size);
                                uvd->fbuf = NULL;
                        }
                        RingQueue_Free(&uvd->dp);
                        for (i=0; i < USBVIDEO_NUMSBUF; i++) {
                                if (uvd->sbuf[i].data != NULL) {
                                        kfree (uvd->sbuf[i].data);
                                        uvd->sbuf[i].data = NULL;
                                }
                        }
                }
        }

        /* If so far no errors then we shall start the camera */
        if (errCode == 0) {
                /* Start data pump if we have valid endpoint */
                if (uvd->video_endp != 0)
                        errCode = GET_CALLBACK(uvd, startDataPump)(uvd);
                if (errCode == 0) {
                        if (VALID_CALLBACK(uvd, setupOnOpen)) {
                                if (uvd->debug > 1)
                                        info("%s: setupOnOpen callback", __FUNCTION__);
                                errCode = GET_CALLBACK(uvd, setupOnOpen)(uvd);
                                if (errCode < 0) {
                                        err("%s: setupOnOpen callback failed (%d.).",
                                            __FUNCTION__, errCode);
                                } else if (uvd->debug > 1) {
                                        info("%s: setupOnOpen callback successful", __FUNCTION__);
                                }
                        }
                        if (errCode == 0) {
                                uvd->settingsAdjusted = 0;
                                if (uvd->debug > 1)
                                        info("%s: Open succeeded.", __FUNCTION__);
                                uvd->user++;
                                file->private_data = uvd;
                        }
                }
        }
        up(&uvd->lock);
        if (errCode != 0)
                usbvideo_ClientDecModCount(uvd);
        if (uvd->debug > 0)
                info("%s: Returning %d.", __FUNCTION__, errCode);
        return errCode;
}

/*
 * usbvideo_v4l_close()
 *
 * This is part of Video 4 Linux API. The procedure
 * stops streaming and deallocates all buffers that were earlier
 * allocated in usbvideo_v4l_open().
 *
 * History:
 * 22-Jan-2000 Moved scratch buffer deallocation here.
 * 27-Jan-2000 Used USBVIDEO_NUMSBUF as number of URB buffers.
 * 24-May-2000 Moved MOD_DEC_USE_COUNT outside of code that can sleep.
 */
static int usbvideo_v4l_close(struct inode *inode, struct file *file)
{
        struct video_device *dev = file->private_data;
        struct uvd *uvd = (struct uvd *) dev;
        int i;

        if (uvd->debug > 1)
                info("%s($%p)", __FUNCTION__, dev);

        down(&uvd->lock);
        GET_CALLBACK(uvd, stopDataPump)(uvd);
        usbvideo_rvfree(uvd->fbuf, uvd->fbuf_size);
        uvd->fbuf = NULL;
        RingQueue_Free(&uvd->dp);

        for (i=0; i < USBVIDEO_NUMSBUF; i++) {
                kfree(uvd->sbuf[i].data);
                uvd->sbuf[i].data = NULL;
        }

#if USBVIDEO_REPORT_STATS
        usbvideo_ReportStatistics(uvd);
#endif    

        uvd->user--;
        if (uvd->remove_pending) {
                if (uvd->debug > 0)
                        info("usbvideo_v4l_close: Final disconnect.");
                usbvideo_CameraRelease(uvd);
        }
        up(&uvd->lock);
        usbvideo_ClientDecModCount(uvd);

        if (uvd->debug > 1)
                info("%s: Completed.", __FUNCTION__);
        file->private_data = NULL;
        return 0;
}

/*
 * usbvideo_v4l_ioctl()
 *
 * This is part of Video 4 Linux API. The procedure handles ioctl() calls.
 *
 * History:
 * 22-Jan-2000 Corrected VIDIOCSPICT to reject unsupported settings.
 */
static int usbvideo_v4l_do_ioctl(struct inode *inode, struct file *file,
                                 unsigned int cmd, void *arg)
{
        struct uvd *uvd = file->private_data;

        if (!CAMERA_IS_OPERATIONAL(uvd))
                return -EIO;

        switch (cmd) {
                case VIDIOCGCAP:
                {
                        struct video_capability *b = arg;
                        *b = uvd->vcap;
                        return 0;
                }
                case VIDIOCGCHAN:
                {
                        struct video_channel *v = arg;
                        *v = uvd->vchan;
                        return 0;
                }
                case VIDIOCSCHAN:
                {       
                        struct video_channel *v = arg;
                        if (v->channel != 0)
                                return -EINVAL;
                        return 0;
                }
                case VIDIOCGPICT:
                {
                        struct video_picture *pic = arg;
                        *pic = uvd->vpic;
                        return 0;
                }
                case VIDIOCSPICT:
                {
                        struct video_picture *pic = arg;
                        /*
                         * Use temporary 'video_picture' structure to preserve our
                         * own settings (such as color depth, palette) that we
                         * aren't allowing everyone (V4L client) to change.
                         */
                        uvd->vpic.brightness = pic->brightness;
                        uvd->vpic.hue = pic->hue;
                        uvd->vpic.colour = pic->colour;
                        uvd->vpic.contrast = pic->contrast;
                        uvd->settingsAdjusted = 0;      /* Will force new settings */
                        return 0;
                }
                case VIDIOCSWIN:
                {
                        struct video_window *vw = arg;

                        if(VALID_CALLBACK(uvd, setVideoMode)) {
                                return GET_CALLBACK(uvd, setVideoMode)(uvd, vw);
                        }

                        if (vw->flags)
                                return -EINVAL;
                        if (vw->clipcount)
                                return -EINVAL;
                        if (vw->width != VIDEOSIZE_X(uvd->canvas))
                                return -EINVAL;
                        if (vw->height != VIDEOSIZE_Y(uvd->canvas))
                                return -EINVAL;

                        return 0;
                }
                case VIDIOCGWIN:
                {
                        struct video_window *vw = arg;

                        vw->x = 0;
                        vw->y = 0;
                        vw->width = VIDEOSIZE_X(uvd->videosize);
                        vw->height = VIDEOSIZE_Y(uvd->videosize);
                        vw->chromakey = 0;
                        if (VALID_CALLBACK(uvd, getFPS))
                                vw->flags = GET_CALLBACK(uvd, getFPS)(uvd);
                        else 
                                vw->flags = 10; /* FIXME: do better! */
                        return 0;
                }
                case VIDIOCGMBUF:
                {
                        struct video_mbuf *vm = arg;
                        int i;

                        memset(vm, 0, sizeof(*vm));
                        vm->size = uvd->max_frame_size * USBVIDEO_NUMFRAMES;
                        vm->frames = USBVIDEO_NUMFRAMES;
                        for(i = 0; i < USBVIDEO_NUMFRAMES; i++) 
                          vm->offsets[i] = i * uvd->max_frame_size;

                        return 0;
                }
                case VIDIOCMCAPTURE:
                {
                        struct video_mmap *vm = arg;

                        if (uvd->debug >= 1) {
                                info("VIDIOCMCAPTURE: frame=%d. size=%dx%d, format=%d.",
                                     vm->frame, vm->width, vm->height, vm->format);
                        }
                        /*
                         * Check if the requested size is supported. If the requestor
                         * requests too big a frame then we may be tricked into accessing
                         * outside of own preallocated frame buffer (in uvd->frame).
                         * This will cause oops or a security hole. Theoretically, we
                         * could only clamp the size down to acceptable bounds, but then
                         * we'd need to figure out how to insert our smaller buffer into
                         * larger caller's buffer... this is not an easy question. So we
                         * here just flatly reject too large requests, assuming that the
                         * caller will resubmit with smaller size. Callers should know
                         * what size we support (returned by VIDIOCGCAP). However vidcat,
                         * for one, does not care and allows to ask for any size.
                         */
                        if ((vm->width > VIDEOSIZE_X(uvd->canvas)) ||
                            (vm->height > VIDEOSIZE_Y(uvd->canvas))) {
                                if (uvd->debug > 0) {
                                        info("VIDIOCMCAPTURE: Size=%dx%d too large; "
                                             "allowed only up to %ldx%ld", vm->width, vm->height,
                                             VIDEOSIZE_X(uvd->canvas), VIDEOSIZE_Y(uvd->canvas));
                                }
                                return -EINVAL;
                        }
                        /* Check if the palette is supported */
                        if (((1L << vm->format) & uvd->paletteBits) == 0) {
                                if (uvd->debug > 0) {
                                        info("VIDIOCMCAPTURE: format=%d. not supported"
                                             " (paletteBits=$%08lx)",
                                             vm->format, uvd->paletteBits);
                                }
                                return -EINVAL;
                        }
                        if ((vm->frame < 0) || (vm->frame >= USBVIDEO_NUMFRAMES)) {
                                err("VIDIOCMCAPTURE: vm.frame=%d. !E [0-%d]", vm->frame, USBVIDEO_NUMFRAMES-1);
                                return -EINVAL;
                        }
                        if (uvd->frame[vm->frame].frameState == FrameState_Grabbing) {
                                /* Not an error - can happen */
                        }
                        uvd->frame[vm->frame].request = VIDEOSIZE(vm->width, vm->height);
                        uvd->frame[vm->frame].palette = vm->format;

                        /* Mark it as ready */
                        uvd->frame[vm->frame].frameState = FrameState_Ready;

                        return usbvideo_NewFrame(uvd, vm->frame);
                }
                case VIDIOCSYNC:
                {
                        int *frameNum = arg;
                        int ret;

                        if (*frameNum < 0 || *frameNum >= USBVIDEO_NUMFRAMES)
                                return -EINVAL;
                                
                        if (uvd->debug >= 1)
                                info("VIDIOCSYNC: syncing to frame %d.", *frameNum);
                        if (uvd->flags & FLAGS_NO_DECODING)
                                ret = usbvideo_GetFrame(uvd, *frameNum);
                        else if (VALID_CALLBACK(uvd, getFrame)) {
                                ret = GET_CALLBACK(uvd, getFrame)(uvd, *frameNum);
                                if ((ret < 0) && (uvd->debug >= 1)) {
                                        err("VIDIOCSYNC: getFrame() returned %d.", ret);
                                }
                        } else {
                                err("VIDIOCSYNC: getFrame is not set");
                                ret = -EFAULT;
                        }

                        /*
                         * The frame is in FrameState_Done_Hold state. Release it
                         * right now because its data is already mapped into
                         * the user space and it's up to the application to
                         * make use of it until it asks for another frame.
                         */
                        uvd->frame[*frameNum].frameState = FrameState_Unused;
                        return ret;
                }
                case VIDIOCGFBUF:
                {
                        struct video_buffer *vb = arg;

                        memset(vb, 0, sizeof(*vb));
                        return 0;
                }
                case VIDIOCKEY:
                        return 0;

                case VIDIOCCAPTURE:
                        return -EINVAL;

                case VIDIOCSFBUF:

                case VIDIOCGTUNER:
                case VIDIOCSTUNER:

                case VIDIOCGFREQ:
                case VIDIOCSFREQ:

                case VIDIOCGAUDIO:
                case VIDIOCSAUDIO:
                        return -EINVAL;

                default:
                        return -ENOIOCTLCMD;
        }
        return 0;
}

static int usbvideo_v4l_ioctl(struct inode *inode, struct file *file,
                       unsigned int cmd, unsigned long arg)
{
        return video_usercopy(inode, file, cmd, arg, usbvideo_v4l_do_ioctl);
}

/*
 * usbvideo_v4l_read()
 *
 * This is mostly boring stuff. We simply ask for a frame and when it
 * arrives copy all the video data from it into user space. There is
 * no obvious need to override this method.
 *
 * History:
 * 20-Oct-2000 Created.
 * 01-Nov-2000 Added mutex (uvd->lock).
 */
static ssize_t usbvideo_v4l_read(struct file *file, char __user *buf,
                      size_t count, loff_t *ppos)
{
        struct uvd *uvd = file->private_data;
        int noblock = file->f_flags & O_NONBLOCK;
        int frmx = -1, i;
        struct usbvideo_frame *frame;

        if (!CAMERA_IS_OPERATIONAL(uvd) || (buf == NULL))
                return -EFAULT;

        if (uvd->debug >= 1)
                info("%s: %Zd. bytes, noblock=%d.", __FUNCTION__, count, noblock);

        down(&uvd->lock);       

        /* See if a frame is completed, then use it. */
        for(i = 0; i < USBVIDEO_NUMFRAMES; i++) {
                if ((uvd->frame[i].frameState == FrameState_Done) ||
                    (uvd->frame[i].frameState == FrameState_Done_Hold) ||
                    (uvd->frame[i].frameState == FrameState_Error)) {
                        frmx = i;
                        break;
                }
        }

        /* FIXME: If we don't start a frame here then who ever does? */
        if (noblock && (frmx == -1)) {
                count = -EAGAIN;
                goto read_done;
        }

        /*
         * If no FrameState_Done, look for a FrameState_Grabbing state.
         * See if a frame is in process (grabbing), then use it.
         * We will need to wait until it becomes cooked, of course.
         */
        if (frmx == -1) {
                for(i = 0; i < USBVIDEO_NUMFRAMES; i++) {
                        if (uvd->frame[i].frameState == FrameState_Grabbing) {
                                frmx = i;
                                break;
                        }
                }
        }

        /*
         * If no frame is active, start one. We don't care which one
         * it will be, so #0 is as good as any.
         * In read access mode we don't have convenience of VIDIOCMCAPTURE
         * to specify the requested palette (video format) on per-frame
         * basis. This means that we have to return data in -some- format
         * and just hope that the client knows what to do with it.
         * The default format is configured in uvd->defaultPalette field
         * as one of VIDEO_PALETTE_xxx values. We stuff it into the new
         * frame and initiate the frame filling process.
         */
        if (frmx == -1) {
                if (uvd->defaultPalette == 0) {
                        err("%s: No default palette; don't know what to do!", __FUNCTION__);
                        count = -EFAULT;
                        goto read_done;
                }
                frmx = 0;
                /*
                 * We have no per-frame control over video size.
                 * Therefore we only can use whatever size was
                 * specified as default.
                 */
                uvd->frame[frmx].request = uvd->videosize;
                uvd->frame[frmx].palette = uvd->defaultPalette;
                uvd->frame[frmx].frameState = FrameState_Ready;
                usbvideo_NewFrame(uvd, frmx);
                /* Now frame 0 is supposed to start filling... */
        }

        /*
         * Get a pointer to the active frame. It is either previously
         * completed frame or frame in progress but not completed yet.
         */
        frame = &uvd->frame[frmx];

        /*
         * Sit back & wait until the frame gets filled and postprocessed.
         * If we fail to get the picture [in time] then return the error.
         * In this call we specify that we want the frame to be waited for,
         * postprocessed and switched into FrameState_Done_Hold state. This
         * state is used to hold the frame as "fully completed" between
         * subsequent partial reads of the same frame.
         */
        if (frame->frameState != FrameState_Done_Hold) {
                long rv = -EFAULT;
                if (uvd->flags & FLAGS_NO_DECODING)
                        rv = usbvideo_GetFrame(uvd, frmx);
                else if (VALID_CALLBACK(uvd, getFrame))
                        rv = GET_CALLBACK(uvd, getFrame)(uvd, frmx);
                else
                        err("getFrame is not set");
                if ((rv != 0) || (frame->frameState != FrameState_Done_Hold)) {
                        count = rv;
                        goto read_done;
                }
        }

        /*
         * Copy bytes to user space. We allow for partial reads, which
         * means that the user application can request read less than
         * the full frame size. It is up to the application to issue
         * subsequent calls until entire frame is read.
         *
         * First things first, make sure we don't copy more than we
         * have - even if the application wants more. That would be
         * a big security embarassment!
         */
        if ((count + frame->seqRead_Index) > frame->seqRead_Length)
                count = frame->seqRead_Length - frame->seqRead_Index;

        /*
         * Copy requested amount of data to user space. We start
         * copying from the position where we last left it, which
         * will be zero for a new frame (not read before).
         */
        if (copy_to_user(buf, frame->data + frame->seqRead_Index, count)) {
                count = -EFAULT;
                goto read_done;
        }

        /* Update last read position */
        frame->seqRead_Index += count;
        if (uvd->debug >= 1) {
                err("%s: {copy} count used=%Zd, new seqRead_Index=%ld",
                        __FUNCTION__, count, frame->seqRead_Index);
        }

        /* Finally check if the frame is done with and "release" it */
        if (frame->seqRead_Index >= frame->seqRead_Length) {
                /* All data has been read */
                frame->seqRead_Index = 0;

                /* Mark it as available to be used again. */
                uvd->frame[frmx].frameState = FrameState_Unused;
                if (usbvideo_NewFrame(uvd, (frmx + 1) % USBVIDEO_NUMFRAMES)) {
                        err("%s: usbvideo_NewFrame failed.", __FUNCTION__);
                }
        }
read_done:
        up(&uvd->lock); 
        return count;
}

/*
 * Make all of the blocks of data contiguous
 */
static int usbvideo_CompressIsochronous(struct uvd *uvd, struct urb *urb)
{
        char *cdata;
        int i, totlen = 0;

        for (i = 0; i < urb->number_of_packets; i++) {
                int n = urb->iso_frame_desc[i].actual_length;
                int st = urb->iso_frame_desc[i].status;

                cdata = urb->transfer_buffer + urb->iso_frame_desc[i].offset;

                /* Detect and ignore errored packets */
                if (st < 0) {
                        if (uvd->debug >= 1)
                                err("Data error: packet=%d. len=%d. status=%d.", i, n, st);
                        uvd->stats.iso_err_count++;
                        continue;
                }

                /* Detect and ignore empty packets */
                if (n <= 0) {
                        uvd->stats.iso_skip_count++;
                        continue;
                }
                totlen += n;    /* Little local accounting */
                RingQueue_Enqueue(&uvd->dp, cdata, n);
        }
        return totlen;
}

static void usbvideo_IsocIrq(struct urb *urb, struct pt_regs *regs)
{
        int i, ret, len;
        struct uvd *uvd = urb->context;

        /* We don't want to do anything if we are about to be removed! */
        if (!CAMERA_IS_OPERATIONAL(uvd))
                return;
#if 0
        if (urb->actual_length > 0) {
                info("urb=$%p status=%d. errcount=%d. length=%d.",
                     urb, urb->status, urb->error_count, urb->actual_length);
        } else {
                static int c = 0;
                if (c++ % 100 == 0)
                        info("No Isoc data");
        }
#endif

        if (!uvd->streaming) {
                if (uvd->debug >= 1)
                        info("Not streaming, but interrupt!");
                return;
        }
        
        uvd->stats.urb_count++;
        if (urb->actual_length <= 0)
                goto urb_done_with;

        /* Copy the data received into ring queue */
        len = usbvideo_CompressIsochronous(uvd, urb);
        uvd->stats.urb_length = len;
        if (len <= 0)
                goto urb_done_with;

        /* Here we got some data */
        uvd->stats.data_count += len;
        RingQueue_WakeUpInterruptible(&uvd->dp);

urb_done_with:
        for (i = 0; i < FRAMES_PER_DESC; i++) {
                urb->iso_frame_desc[i].status = 0;
                urb->iso_frame_desc[i].actual_length = 0;
        }
        urb->status = 0;
        urb->dev = uvd->dev;
        ret = usb_submit_urb (urb, GFP_KERNEL);
        if(ret)
                err("usb_submit_urb error (%d)", ret);
        return;
}

/*
 * usbvideo_StartDataPump()
 *
 * History:
 * 27-Jan-2000 Used ibmcam->iface, ibmcam->ifaceAltActive instead
 *             of hardcoded values. Simplified by using for loop,
 *             allowed any number of URBs.
 */
static int usbvideo_StartDataPump(struct uvd *uvd)
{
        struct usb_device *dev = uvd->dev;
        int i, errFlag;

        if (uvd->debug > 1)
                info("%s($%p)", __FUNCTION__, uvd);

        if (!CAMERA_IS_OPERATIONAL(uvd)) {
                err("%s: Camera is not operational", __FUNCTION__);
                return -EFAULT;
        }
        uvd->curframe = -1;

        /* Alternate interface 1 is is the biggest frame size */
        i = usb_set_interface(dev, uvd->iface, uvd->ifaceAltActive);
        if (i < 0) {
                err("%s: usb_set_interface error", __FUNCTION__);
                uvd->last_error = i;
                return -EBUSY;
        }
        if (VALID_CALLBACK(uvd, videoStart))
                GET_CALLBACK(uvd, videoStart)(uvd);
        else 
                err("%s: videoStart not set", __FUNCTION__);

        /* We double buffer the Iso lists */
        for (i=0; i < USBVIDEO_NUMSBUF; i++) {
                int j, k;
                struct urb *urb = uvd->sbuf[i].urb;
                urb->dev = dev;
                urb->context = uvd;
                urb->pipe = usb_rcvisocpipe(dev, uvd->video_endp);
                urb->interval = 1;
                urb->transfer_flags = URB_ISO_ASAP;
                urb->transfer_buffer = uvd->sbuf[i].data;
                urb->complete = usbvideo_IsocIrq;
                urb->number_of_packets = FRAMES_PER_DESC;
                urb->transfer_buffer_length = uvd->iso_packet_len * FRAMES_PER_DESC;
                for (j=k=0; j < FRAMES_PER_DESC; j++, k += uvd->iso_packet_len) {
                        urb->iso_frame_desc[j].offset = k;
                        urb->iso_frame_desc[j].length = uvd->iso_packet_len;
                }
        }

        /* Submit all URBs */
        for (i=0; i < USBVIDEO_NUMSBUF; i++) {
                errFlag = usb_submit_urb(uvd->sbuf[i].urb, GFP_KERNEL);
                if (errFlag)
                        err("%s: usb_submit_isoc(%d) ret %d", __FUNCTION__, i, errFlag);
        }

        uvd->streaming = 1;
        if (uvd->debug > 1)
                info("%s: streaming=1 video_endp=$%02x", __FUNCTION__, uvd->video_endp);
        return 0;
}

/*
 * usbvideo_StopDataPump()
 *
 * This procedure stops streaming and deallocates URBs. Then it
 * activates zero-bandwidth alt. setting of the video interface.
 *
 * History:
 * 22-Jan-2000 Corrected order of actions to work after surprise removal.
 * 27-Jan-2000 Used uvd->iface, uvd->ifaceAltInactive instead of hardcoded values.
 */
static void usbvideo_StopDataPump(struct uvd *uvd)
{
        int i, j;

        if ((uvd == NULL) || (!uvd->streaming) || (uvd->dev == NULL))
                return;

        if (uvd->debug > 1)
                info("%s($%p)", __FUNCTION__, uvd);

        /* Unschedule all of the iso td's */
        for (i=0; i < USBVIDEO_NUMSBUF; i++) {
                usb_kill_urb(uvd->sbuf[i].urb);
        }
        if (uvd->debug > 1)
                info("%s: streaming=0", __FUNCTION__);
        uvd->streaming = 0;

        if (!uvd->remove_pending) {
                /* Invoke minidriver's magic to stop the camera */
                if (VALID_CALLBACK(uvd, videoStop))
                        GET_CALLBACK(uvd, videoStop)(uvd);
                else 
                        err("%s: videoStop not set", __FUNCTION__);

                /* Set packet size to 0 */
                j = usb_set_interface(uvd->dev, uvd->iface, uvd->ifaceAltInactive);
                if (j < 0) {
                        err("%s: usb_set_interface() error %d.", __FUNCTION__, j);
                        uvd->last_error = j;
                }
        }
}

/*
 * usbvideo_NewFrame()
 *
 * History:
 * 29-Mar-00 Added copying of previous frame into the current one.
 * 6-Aug-00  Added model 3 video sizes, removed redundant width, height.
 */
static int usbvideo_NewFrame(struct uvd *uvd, int framenum)
{
        struct usbvideo_frame *frame;
        int n;

        if (uvd->debug > 1)
                info("usbvideo_NewFrame($%p,%d.)", uvd, framenum);

        /* If we're not grabbing a frame right now and the other frame is */
        /*  ready to be grabbed into, then use it instead */
        if (uvd->curframe != -1)
                return 0;

        /* If necessary we adjust picture settings between frames */
        if (!uvd->settingsAdjusted) {
                if (VALID_CALLBACK(uvd, adjustPicture))
                        GET_CALLBACK(uvd, adjustPicture)(uvd);
                uvd->settingsAdjusted = 1;
        }

        n = (framenum + 1) % USBVIDEO_NUMFRAMES;
        if (uvd->frame[n].frameState == FrameState_Ready)
                framenum = n;

        frame = &uvd->frame[framenum];

        frame->frameState = FrameState_Grabbing;
        frame->scanstate = ScanState_Scanning;
        frame->seqRead_Length = 0;      /* Accumulated in xxx_parse_data() */
        frame->deinterlace = Deinterlace_None;
        frame->flags = 0; /* No flags yet, up to minidriver (or us) to set them */
        uvd->curframe = framenum;

        /*
         * Normally we would want to copy previous frame into the current one
         * before we even start filling it with data; this allows us to stop
         * filling at any moment; top portion of the frame will be new and
         * bottom portion will stay as it was in previous frame. If we don't
         * do that then missing chunks of video stream will result in flickering
         * portions of old data whatever it was before.
         *
         * If we choose not to copy previous frame (to, for example, save few
         * bus cycles - the frame can be pretty large!) then we have an option
         * to clear the frame before using. If we experience losses in this
         * mode then missing picture will be black (no flickering).
         *
         * Finally, if user chooses not to clean the current frame before
         * filling it with data then the old data will be visible if we fail
         * to refill entire frame with new data.
         */
        if (!(uvd->flags & FLAGS_SEPARATE_FRAMES)) {
                /* This copies previous frame into this one to mask losses */
                int prev = (framenum - 1 + USBVIDEO_NUMFRAMES) % USBVIDEO_NUMFRAMES;
                memmove(frame->data, uvd->frame[prev].data, uvd->max_frame_size);
        } else {
                if (uvd->flags & FLAGS_CLEAN_FRAMES) {
                        /* This provides a "clean" frame but slows things down */
                        memset(frame->data, 0, uvd->max_frame_size);
                }
        }
        return 0;
}

/*
 * usbvideo_CollectRawData()
 *
 * This procedure can be used instead of 'processData' callback if you
 * only want to dump the raw data from the camera into the output
 * device (frame buffer). You can look at it with V4L client, but the
 * image will be unwatchable. The main purpose of this code and of the
 * mode FLAGS_NO_DECODING is debugging and capturing of datastreams from
 * new, unknown cameras. This procedure will be automatically invoked
 * instead of the specified callback handler when uvd->flags has bit
 * FLAGS_NO_DECODING set. Therefore, any regular build of any driver
 * based on usbvideo can use this feature at any time.
 */
static void usbvideo_CollectRawData(struct uvd *uvd, struct usbvideo_frame *frame)
{
        int n;

        assert(uvd != NULL);
        assert(frame != NULL);

        /* Try to move data from queue into frame buffer */
        n = RingQueue_GetLength(&uvd->dp);
        if (n > 0) {
                int m;
                /* See how much space we have left */
                m = uvd->max_frame_size - frame->seqRead_Length;
                if (n > m)
                        n = m;
                /* Now move that much data into frame buffer */
                RingQueue_Dequeue(
                        &uvd->dp,
                        frame->data + frame->seqRead_Length,
                        m);
                frame->seqRead_Length += m;
        }
        /* See if we filled the frame */
        if (frame->seqRead_Length >= uvd->max_frame_size) {
                frame->frameState = FrameState_Done;
                uvd->curframe = -1;
                uvd->stats.frame_num++;
        }
}

static int usbvideo_GetFrame(struct uvd *uvd, int frameNum)
{
        struct usbvideo_frame *frame = &uvd->frame[frameNum];

        if (uvd->debug >= 2)
                info("%s($%p,%d.)", __FUNCTION__, uvd, frameNum);

        switch (frame->frameState) {
        case FrameState_Unused:
                if (uvd->debug >= 2)
                        info("%s: FrameState_Unused", __FUNCTION__);
                return -EINVAL;
        case FrameState_Ready:
        case FrameState_Grabbing:
        case FrameState_Error:
        {
                int ntries, signalPending;
        redo:
                if (!CAMERA_IS_OPERATIONAL(uvd)) {
                        if (uvd->debug >= 2)
                                info("%s: Camera is not operational (1)", __FUNCTION__);
                        return -EIO;
                }
                ntries = 0; 
                do {
                        RingQueue_InterruptibleSleepOn(&uvd->dp);
                        signalPending = signal_pending(current);
                        if (!CAMERA_IS_OPERATIONAL(uvd)) {
                                if (uvd->debug >= 2)
                                        info("%s: Camera is not operational (2)", __FUNCTION__);
                                return -EIO;
                        }
                        assert(uvd->fbuf != NULL);
                        if (signalPending) {
                                if (uvd->debug >= 2)
                                        info("%s: Signal=$%08x", __FUNCTION__, signalPending);
                                if (uvd->flags & FLAGS_RETRY_VIDIOCSYNC) {
                                        usbvideo_TestPattern(uvd, 1, 0);
                                        uvd->curframe = -1;
                                        uvd->stats.frame_num++;
                                        if (uvd->debug >= 2)
                                                info("%s: Forced test pattern screen", __FUNCTION__);
                                        return 0;
                                } else {
                                        /* Standard answer: Interrupted! */
                                        if (uvd->debug >= 2)
                                                info("%s: Interrupted!", __FUNCTION__);
                                        return -EINTR;
                                }
                        } else {
                                /* No signals - we just got new data in dp queue */
                                if (uvd->flags & FLAGS_NO_DECODING)
                                        usbvideo_CollectRawData(uvd, frame);
                                else if (VALID_CALLBACK(uvd, processData))
                                        GET_CALLBACK(uvd, processData)(uvd, frame);
                                else 
                                        err("%s: processData not set", __FUNCTION__);
                        }
                } while (frame->frameState == FrameState_Grabbing);
                if (uvd->debug >= 2) {
                        info("%s: Grabbing done; state=%d. (%lu. bytes)",
                             __FUNCTION__, frame->frameState, frame->seqRead_Length);
                }
                if (frame->frameState == FrameState_Error) {
                        int ret = usbvideo_NewFrame(uvd, frameNum);
                        if (ret < 0) {
                                err("%s: usbvideo_NewFrame() failed (%d.)", __FUNCTION__, ret);
                                return ret;
                        }
                        goto redo;
                }
                /* Note that we fall through to meet our destiny below */
        }
        case FrameState_Done:
                /*
                 * Do all necessary postprocessing of data prepared in
                 * "interrupt" code and the collecting code above. The
                 * frame gets marked as FrameState_Done by queue parsing code.
                 * This status means that we collected enough data and
                 * most likely processed it as we went through. However
                 * the data may need postprocessing, such as deinterlacing
                 * or picture adjustments implemented in software (horror!)
                 *
                 * As soon as the frame becomes "final" it gets promoted to
                 * FrameState_Done_Hold status where it will remain until the
                 * caller consumed all the video data from the frame. Then
                 * the empty shell of ex-frame is thrown out for dogs to eat.
                 * But we, worried about pets, will recycle the frame!
                 */
                uvd->stats.frame_num++;
                if ((uvd->flags & FLAGS_NO_DECODING) == 0) {
                        if (VALID_CALLBACK(uvd, postProcess))
                                GET_CALLBACK(uvd, postProcess)(uvd, frame);
                        if (frame->flags & USBVIDEO_FRAME_FLAG_SOFTWARE_CONTRAST)
                                usbvideo_SoftwareContrastAdjustment(uvd, frame);
                }
                frame->frameState = FrameState_Done_Hold;
                if (uvd->debug >= 2)
                        info("%s: Entered FrameState_Done_Hold state.", __FUNCTION__);
                return 0;

        case FrameState_Done_Hold:
                /*
                 * We stay in this state indefinitely until someone external,
                 * like ioctl() or read() call finishes digesting the frame
                 * data. Then it will mark the frame as FrameState_Unused and
                 * it will be released back into the wild to roam freely.
                 */
                if (uvd->debug >= 2)
                        info("%s: FrameState_Done_Hold state.", __FUNCTION__);
                return 0;
        }

        /* Catch-all for other cases. We shall not be here. */
        err("%s: Invalid state %d.", __FUNCTION__, frame->frameState);
        frame->frameState = FrameState_Unused;
        return 0;
}

/*
 * usbvideo_DeinterlaceFrame()
 *
 * This procedure deinterlaces the given frame. Some cameras produce
 * only half of scanlines - sometimes only even lines, sometimes only
 * odd lines. The deinterlacing method is stored in frame->deinterlace
 * variable.
 *
 * Here we scan the frame vertically and replace missing scanlines with
 * average between surrounding ones - before and after. If we have no
 * line above then we just copy next line. Similarly, if we need to
 * create a last line then preceding line is used.
 */
void usbvideo_DeinterlaceFrame(struct uvd *uvd, struct usbvideo_frame *frame)
{
        if ((uvd == NULL) || (frame == NULL))
                return;

        if ((frame->deinterlace == Deinterlace_FillEvenLines) ||
            (frame->deinterlace == Deinterlace_FillOddLines))
        {
                const int v4l_linesize = VIDEOSIZE_X(frame->request) * V4L_BYTES_PER_PIXEL;
                int i = (frame->deinterlace == Deinterlace_FillEvenLines) ? 0 : 1;

                for (; i < VIDEOSIZE_Y(frame->request); i += 2) {
                        const unsigned char *fs1, *fs2;
                        unsigned char *fd;
                        int ip, in, j;  /* Previous and next lines */

                        /*
                         * Need to average lines before and after 'i'.
                         * If we go out of bounds seeking those lines then
                         * we point back to existing line.
                         */
                        ip = i - 1;     /* First, get rough numbers */
                        in = i + 1;

                        /* Now validate */
                        if (ip < 0)
                                ip = in;
                        if (in >= VIDEOSIZE_Y(frame->request))
                                in = ip;

                        /* Sanity check */
                        if ((ip < 0) || (in < 0) ||
                            (ip >= VIDEOSIZE_Y(frame->request)) ||
                            (in >= VIDEOSIZE_Y(frame->request)))
                        {
                                err("Error: ip=%d. in=%d. req.height=%ld.",
                                    ip, in, VIDEOSIZE_Y(frame->request));
                                break;
                        }

                        /* Now we need to average lines 'ip' and 'in' to produce line 'i' */
                        fs1 = frame->data + (v4l_linesize * ip);
                        fs2 = frame->data + (v4l_linesize * in);
                        fd = frame->data + (v4l_linesize * i);

                        /* Average lines around destination */
                        for (j=0; j < v4l_linesize; j++) {
                                fd[j] = (unsigned char)((((unsigned) fs1[j]) +
                                                         ((unsigned)fs2[j])) >> 1);
                        }
                }
        }

        /* Optionally display statistics on the screen */
        if (uvd->flags & FLAGS_OVERLAY_STATS)
                usbvideo_OverlayStats(uvd, frame);
}

EXPORT_SYMBOL(usbvideo_DeinterlaceFrame);

/*
 * usbvideo_SoftwareContrastAdjustment()
 *
 * This code adjusts the contrast of the frame, assuming RGB24 format.
 * As most software image processing, this job is CPU-intensive.
 * Get a camera that supports hardware adjustment!
 *
 * History:
 * 09-Feb-2001  Created.
 */
static void usbvideo_SoftwareContrastAdjustment(struct uvd *uvd, 
                                                struct usbvideo_frame *frame)
{
        int i, j, v4l_linesize;
        signed long adj;
        const int ccm = 128; /* Color correction median - see below */

        if ((uvd == NULL) || (frame == NULL)) {
                err("%s: Illegal call.", __FUNCTION__);
                return;
        }
        adj = (uvd->vpic.contrast - 0x8000) >> 8; /* -128..+127 = -ccm..+(ccm-1)*/
        RESTRICT_TO_RANGE(adj, -ccm, ccm+1);
        if (adj == 0) {
                /* In rare case of no adjustment */
                return;
        }
        v4l_linesize = VIDEOSIZE_X(frame->request) * V4L_BYTES_PER_PIXEL;
        for (i=0; i < VIDEOSIZE_Y(frame->request); i++) {
                unsigned char *fd = frame->data + (v4l_linesize * i);
                for (j=0; j < v4l_linesize; j++) {
                        signed long v = (signed long) fd[j];
                        /* Magnify up to 2 times, reduce down to zero */
                        v = 128 + ((ccm + adj) * (v - 128)) / ccm;
                        RESTRICT_TO_RANGE(v, 0, 0xFF); /* Must flatten tails */
                        fd[j] = (unsigned char) v;
                }
        }
}

MODULE_LICENSE("GPL");