linux/drivers/usb/media/sn9c102_core.c

/***************************************************************************
 * V4L2 driver for SN9C10x PC Camera Controllers                           *
 *                                                                         *
 * Copyright (C) 2004-2005 by Luca Risolia <luca.risolia@studio.unibo.it>  *
 *                                                                         *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.               *
 ***************************************************************************/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/delay.h>
#include <linux/stddef.h>
#include <linux/compiler.h>
#include <linux/ioctl.h>
#include <linux/poll.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/page-flags.h>
#include <linux/byteorder/generic.h>
#include <asm/page.h>
#include <asm/uaccess.h>

#include "sn9c102.h"

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

MODULE_DEVICE_TABLE(usb, sn9c102_id_table);

MODULE_AUTHOR(SN9C102_MODULE_AUTHOR " " SN9C102_AUTHOR_EMAIL);
MODULE_DESCRIPTION(SN9C102_MODULE_NAME);
MODULE_VERSION(SN9C102_MODULE_VERSION);
MODULE_LICENSE(SN9C102_MODULE_LICENSE);

static short video_nr[] = {[0 ... SN9C102_MAX_DEVICES-1] = -1};
module_param_array(video_nr, short, NULL, 0444);
MODULE_PARM_DESC(video_nr,
                 "\n<-1|n[,...]> Specify V4L2 minor mode number."
                 "\n -1 = use next available (default)"
                 "\n  n = use minor number n (integer >= 0)"
                 "\nYou can specify up to "__MODULE_STRING(SN9C102_MAX_DEVICES)
                 " cameras this way."
                 "\nFor example:"
                 "\nvideo_nr=-1,2,-1 would assign minor number 2 to"
                 "\nthe second camera and use auto for the first"
                 "\none and for every other camera."
                 "\n");

static short force_munmap[] = {[0 ... SN9C102_MAX_DEVICES-1] = 
                               SN9C102_FORCE_MUNMAP};
module_param_array(force_munmap, bool, NULL, 0444);
MODULE_PARM_DESC(force_munmap,
                 "\n<0|1[,...]> Force the application to unmap previously "
                 "\nmapped buffer memory before calling any VIDIOC_S_CROP or "
                 "\nVIDIOC_S_FMT ioctl's. Not all the applications support "
                 "\nthis feature. This parameter is specific for each "
                 "\ndetected camera."
                 "\n 0 = do not force memory unmapping"
                 "\n 1 = force memory unmapping (save memory)"
                 "\nDefault value is "__MODULE_STRING(SN9C102_FORCE_MUNMAP)"."
                 "\n");

#ifdef SN9C102_DEBUG
static unsigned short debug = SN9C102_DEBUG_LEVEL;
module_param(debug, ushort, 0644);
MODULE_PARM_DESC(debug,
                 "\n<n> Debugging information level, from 0 to 3:"
                 "\n0 = none (use carefully)"
                 "\n1 = critical errors"
                 "\n2 = significant informations"
                 "\n3 = more verbose messages"
                 "\nLevel 3 is useful for testing only, when only "
                 "one device is used."
                 "\nDefault value is "__MODULE_STRING(SN9C102_DEBUG_LEVEL)"."
                 "\n");
#endif

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

static sn9c102_sof_header_t sn9c102_sof_header[] = {
	{0xff, 0xff, 0x00, 0xc4, 0xc4, 0x96, 0x00},
	{0xff, 0xff, 0x00, 0xc4, 0xc4, 0x96, 0x01},
};


static sn9c102_eof_header_t sn9c102_eof_header[] = {
	{0x00, 0x00, 0x00, 0x00},
	{0x40, 0x00, 0x00, 0x00},
	{0x80, 0x00, 0x00, 0x00},
	{0xc0, 0x00, 0x00, 0x00},
};

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

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

	size = PAGE_ALIGN(size);

	mem = vmalloc_32((unsigned long)size);
	if (!mem)
		return NULL;

	memset(mem, 0, size);

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

	return mem;
}


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

	if (!mem)
		return;

	size = PAGE_ALIGN(size);

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

	vfree(mem);
}


static u32 
sn9c102_request_buffers(struct sn9c102_device* cam, u32 count, 
                        enum sn9c102_io_method io)
{
	struct v4l2_pix_format* p = &(cam->sensor->pix_format);
	struct v4l2_rect* r = &(cam->sensor->cropcap.bounds);
	const size_t imagesize = cam->module_param.force_munmap ||
	                         io == IO_READ ?
	                         (p->width * p->height * p->priv) / 8 :
	                         (r->width * r->height * p->priv) / 8;
	void* buff = NULL;
	u32 i;

	if (count > SN9C102_MAX_FRAMES)
		count = SN9C102_MAX_FRAMES;

	cam->nbuffers = count;
	while (cam->nbuffers > 0) {
		if ((buff = rvmalloc(cam->nbuffers * PAGE_ALIGN(imagesize))))
			break;
		cam->nbuffers--;
	}

	for (i = 0; i < cam->nbuffers; i++) {
		cam->frame[i].bufmem = buff + i*PAGE_ALIGN(imagesize);
		cam->frame[i].buf.index = i;
		cam->frame[i].buf.m.offset = i*PAGE_ALIGN(imagesize);
		cam->frame[i].buf.length = imagesize;
		cam->frame[i].buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		cam->frame[i].buf.sequence = 0;
		cam->frame[i].buf.field = V4L2_FIELD_NONE;
		cam->frame[i].buf.memory = V4L2_MEMORY_MMAP;
		cam->frame[i].buf.flags = 0;
	}

	return cam->nbuffers;
}


static void sn9c102_release_buffers(struct sn9c102_device* cam)
{
	if (cam->nbuffers) {
		rvfree(cam->frame[0].bufmem,
		       cam->nbuffers * cam->frame[0].buf.length);
		cam->nbuffers = 0;
	}
}


static void sn9c102_empty_framequeues(struct sn9c102_device* cam)
{
	u32 i;

	INIT_LIST_HEAD(&cam->inqueue);
	INIT_LIST_HEAD(&cam->outqueue);

	for (i = 0; i < SN9C102_MAX_FRAMES; i++) {
		cam->frame[i].state = F_UNUSED;
		cam->frame[i].buf.bytesused = 0;
	}
}


static void sn9c102_queue_unusedframes(struct sn9c102_device* cam)
{
	unsigned long lock_flags;
	u32 i;

	for (i = 0; i < cam->nbuffers; i++)
		if (cam->frame[i].state == F_UNUSED) {
			cam->frame[i].state = F_QUEUED;
			spin_lock_irqsave(&cam->queue_lock, lock_flags);
			list_add_tail(&cam->frame[i].frame, &cam->inqueue);
			spin_unlock_irqrestore(&cam->queue_lock, lock_flags);
		}
}

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

int sn9c102_write_reg(struct sn9c102_device* cam, u8 value, u16 index)
{
	struct usb_device* udev = cam->usbdev;
	u8* buff = cam->control_buffer;
	int res;

	*buff = value;

	res = usb_control_msg(udev, usb_sndctrlpipe(udev, 0), 0x08, 0x41,
	                      index, 0, buff, 1, SN9C102_CTRL_TIMEOUT);
	if (res < 0) {
		DBG(3, "Failed to write a register (value 0x%02X, index "
		       "0x%02X, error %d)", value, index, res)
		return -1;
	}

	cam->reg[index] = value;

	return 0;
}


/* NOTE: reading some registers always returns 0 */
static int sn9c102_read_reg(struct sn9c102_device* cam, u16 index)
{
	struct usb_device* udev = cam->usbdev;
	u8* buff = cam->control_buffer;
	int res;

	res = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), 0x00, 0xc1,
	                      index, 0, buff, 1, SN9C102_CTRL_TIMEOUT);
	if (res < 0)
		DBG(3, "Failed to read a register (index 0x%02X, error %d)",
		    index, res)

	return (res >= 0) ? (int)(*buff) : -1;
}


int sn9c102_pread_reg(struct sn9c102_device* cam, u16 index)
{
	if (index > 0x1f)
		return -EINVAL;

	return cam->reg[index];
}


static int
sn9c102_i2c_wait(struct sn9c102_device* cam, struct sn9c102_sensor* sensor)
{
	int i, r;

	for (i = 1; i <= 5; i++) {
		r = sn9c102_read_reg(cam, 0x08);
		if (r < 0)
			return -EIO;
		if (r & 0x04)
			return 0;
		if (sensor->frequency & SN9C102_I2C_400KHZ)
			udelay(5*16);
		else
			udelay(16*16);
	}
	return -EBUSY;
}


static int
sn9c102_i2c_detect_read_error(struct sn9c102_device* cam, 
                              struct sn9c102_sensor* sensor)
{
	int r;
	r = sn9c102_read_reg(cam, 0x08);
	return (r < 0 || (r >= 0 && !(r & 0x08))) ? -EIO : 0;
}


static int
sn9c102_i2c_detect_write_error(struct sn9c102_device* cam, 
                               struct sn9c102_sensor* sensor)
{
	int r;
	r = sn9c102_read_reg(cam, 0x08);
	return (r < 0 || (r >= 0 && (r & 0x08))) ? -EIO : 0;
}


int 
sn9c102_i2c_try_raw_read(struct sn9c102_device* cam,
                         struct sn9c102_sensor* sensor, u8 data0, u8 data1,
                         u8 n, u8 buffer[])
{
	struct usb_device* udev = cam->usbdev;
	u8* data = cam->control_buffer;
	int err = 0, res;

	/* Write cycle */
	data[0] = ((sensor->interface == SN9C102_I2C_2WIRES) ? 0x80 : 0) |
	          ((sensor->frequency & SN9C102_I2C_400KHZ) ? 0x01 : 0) | 0x10;
	data[1] = data0; /* I2C slave id */
	data[2] = data1; /* address */
	data[7] = 0x10;
	res = usb_control_msg(udev, usb_sndctrlpipe(udev, 0), 0x08, 0x41,
	                      0x08, 0, data, 8, SN9C102_CTRL_TIMEOUT);
	if (res < 0)
		err += res;

	err += sn9c102_i2c_wait(cam, sensor);

	/* Read cycle - n bytes */
	data[0] = ((sensor->interface == SN9C102_I2C_2WIRES) ? 0x80 : 0) |
	          ((sensor->frequency & SN9C102_I2C_400KHZ) ? 0x01 : 0) |
	          (n << 4) | 0x02;
	data[1] = data0;
	data[7] = 0x10;
	res = usb_control_msg(udev, usb_sndctrlpipe(udev, 0), 0x08, 0x41,
	                      0x08, 0, data, 8, SN9C102_CTRL_TIMEOUT);
	if (res < 0)
		err += res;

	err += sn9c102_i2c_wait(cam, sensor);

	/* The first read byte will be placed in data[4] */
	res = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), 0x00, 0xc1,
	                      0x0a, 0, data, 5, SN9C102_CTRL_TIMEOUT);
	if (res < 0)
		err += res;

	err += sn9c102_i2c_detect_read_error(cam, sensor);

	PDBGG("I2C read: address 0x%02X, first read byte: 0x%02X", data1,
	      data[4])

	if (err) {
		DBG(3, "I2C read failed for %s image sensor", sensor->name)
		return -1;
	}

	if (buffer)
		memcpy(buffer, data, sizeof(buffer));

	return (int)data[4];
}


int 
sn9c102_i2c_try_raw_write(struct sn9c102_device* cam,
                          struct sn9c102_sensor* sensor, u8 n, u8 data0,
                          u8 data1, u8 data2, u8 data3, u8 data4, u8 data5)
{
	struct usb_device* udev = cam->usbdev;
	u8* data = cam->control_buffer;
	int err = 0, res;

	/* Write cycle. It usually is address + value */
	data[0] = ((sensor->interface == SN9C102_I2C_2WIRES) ? 0x80 : 0) |
	          ((sensor->frequency & SN9C102_I2C_400KHZ) ? 0x01 : 0)
	          | ((n - 1) << 4);
	data[1] = data0;
	data[2] = data1;
	data[3] = data2;
	data[4] = data3;
	data[5] = data4;
	data[6] = data5;
	data[7] = 0x14;
	res = usb_control_msg(udev, usb_sndctrlpipe(udev, 0), 0x08, 0x41,
	                      0x08, 0, data, 8, SN9C102_CTRL_TIMEOUT);
	if (res < 0)
		err += res;

	err += sn9c102_i2c_wait(cam, sensor);
	err += sn9c102_i2c_detect_write_error(cam, sensor);

	if (err)
		DBG(3, "I2C write failed for %s image sensor", sensor->name)

	PDBGG("I2C raw write: %u bytes, data0 = 0x%02X, data1 = 0x%02X, "
	      "data2 = 0x%02X, data3 = 0x%02X, data4 = 0x%02X, data5 = 0x%02X",
	      n, data0, data1, data2, data3, data4, data5)

	return err ? -1 : 0;
}


int
sn9c102_i2c_try_read(struct sn9c102_device* cam,
                     struct sn9c102_sensor* sensor, u8 address)
{
	return sn9c102_i2c_try_raw_read(cam, sensor, sensor->i2c_slave_id,
	                                address, 1, NULL);
}


int
sn9c102_i2c_try_write(struct sn9c102_device* cam,
                      struct sn9c102_sensor* sensor, u8 address, u8 value)
{
	return sn9c102_i2c_try_raw_write(cam, sensor, 3, 
	                                 sensor->i2c_slave_id, address,
	                                 value, 0, 0, 0);
}


int sn9c102_i2c_read(struct sn9c102_device* cam, u8 address)
{
	if (!cam->sensor)
		return -1;

	return sn9c102_i2c_try_read(cam, cam->sensor, address);
}


int sn9c102_i2c_write(struct sn9c102_device* cam, u8 address, u8 value)
{
	if (!cam->sensor)
		return -1;

	return sn9c102_i2c_try_write(cam, cam->sensor, address, value);
}

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

static void*
sn9c102_find_sof_header(struct sn9c102_device* cam, void* mem, size_t len)
{
	size_t soflen = sizeof(sn9c102_sof_header_t), i;
	u8 j, n = sizeof(sn9c102_sof_header) / soflen;

	for (i = 0; (len >= soflen) && (i <= len - soflen); i++)
		for (j = 0; j < n; j++)
			/* It's enough to compare 7 bytes */
			if (!memcmp(mem + i, sn9c102_sof_header[j], 7)) {
				memcpy(cam->sof_header, mem + i, soflen);
				/* Skip the header */
				return mem + i + soflen;
			}

	return NULL;
}


static void*
sn9c102_find_eof_header(struct sn9c102_device* cam, void* mem, size_t len)
{
	size_t eoflen = sizeof(sn9c102_eof_header_t), i;
	unsigned j, n = sizeof(sn9c102_eof_header) / eoflen;

	if (cam->sensor->pix_format.pixelformat == V4L2_PIX_FMT_SN9C10X)
		return NULL; /* EOF header does not exist in compressed data */

	for (i = 0; (len >= eoflen) && (i <= len - eoflen); i++)
		for (j = 0; j < n; j++)
			if (!memcmp(mem + i, sn9c102_eof_header[j], eoflen))
				return mem + i;

	return NULL;
}


static void sn9c102_urb_complete(struct urb *urb, struct pt_regs* regs)
{
	struct sn9c102_device* cam = urb->context;
	struct sn9c102_frame_t** f;
	size_t imagesize;
	unsigned long lock_flags;
	u8 i;
	int err = 0;

	if (urb->status == -ENOENT)
		return;

	f = &cam->frame_current;

	if (cam->stream == STREAM_INTERRUPT) {
		cam->stream = STREAM_OFF;
		if ((*f))
			(*f)->state = F_QUEUED;
		DBG(3, "Stream interrupted")
		wake_up_interruptible(&cam->wait_stream);
	}

	if (cam->state & DEV_DISCONNECTED)
		return;

	if (cam->state & DEV_MISCONFIGURED) {
		wake_up_interruptible(&cam->wait_frame);
		return;
	}

	if (cam->stream == STREAM_OFF || list_empty(&cam->inqueue))
		goto resubmit_urb;

	if (!(*f))
		(*f) = list_entry(cam->inqueue.next, struct sn9c102_frame_t,
		                  frame);

	imagesize = (cam->sensor->pix_format.width *
	             cam->sensor->pix_format.height *
	             cam->sensor->pix_format.priv) / 8;

	for (i = 0; i < urb->number_of_packets; i++) {
		unsigned int img, len, status;
		void *pos, *sof, *eof;

		len = urb->iso_frame_desc[i].actual_length;
		status = urb->iso_frame_desc[i].status;
		pos = urb->iso_frame_desc[i].offset + urb->transfer_buffer;

		if (status) {
			DBG(3, "Error in isochronous frame")
			(*f)->state = F_ERROR;
			continue;
		}

		PDBGG("Isochrnous frame: length %u, #%u i", len, i)

		/*
		   NOTE: It is probably correct to assume that SOF and EOF
		         headers do not occur between two consecutive packets,
		         but who knows..Whatever is the truth, this assumption
		         doesn't introduce bugs.
		*/

redo:
		sof = sn9c102_find_sof_header(cam, pos, len);
		if (!sof) {
			eof = sn9c102_find_eof_header(cam, pos, len);
			if ((*f)->state == F_GRABBING) {
end_of_frame:
				img = len;

				if (eof)
					img = (eof > pos) ? eof - pos - 1 : 0;

				if ((*f)->buf.bytesused+img > imagesize) {
					u32 b = (*f)->buf.bytesused + img -
					        imagesize;
					img = imagesize - (*f)->buf.bytesused;
					DBG(3, "Expected EOF not found: "
					       "video frame cut")
					if (eof)
						DBG(3, "Exceeded limit: +%u "
						       "bytes", (unsigned)(b))
				}

				memcpy((*f)->bufmem + (*f)->buf.bytesused, pos,
				       img);

				if ((*f)->buf.bytesused == 0)
					do_gettimeofday(&(*f)->buf.timestamp);

				(*f)->buf.bytesused += img;

				if ((*f)->buf.bytesused == imagesize ||
				    (cam->sensor->pix_format.pixelformat ==
				                V4L2_PIX_FMT_SN9C10X && eof)) {
					u32 b = (*f)->buf.bytesused;
					(*f)->state = F_DONE;
					(*f)->buf.sequence= ++cam->frame_count;
					spin_lock_irqsave(&cam->queue_lock,
					                  lock_flags);
					list_move_tail(&(*f)->frame,
					               &cam->outqueue);
					if (!list_empty(&cam->inqueue))
						(*f) = list_entry(
						        cam->inqueue.next,
						        struct sn9c102_frame_t,
						        frame );
					else
						(*f) = NULL;
					spin_unlock_irqrestore(&cam->queue_lock
					                       , lock_flags);
					memcpy(cam->sysfs.frame_header,
					       cam->sof_header,
					       sizeof(sn9c102_sof_header_t));
					DBG(3, "Video frame captured: "
					       "%lu bytes", (unsigned long)(b))

					if (!(*f))
						goto resubmit_urb;

				} else if (eof) {
					(*f)->state = F_ERROR;
					DBG(3, "Not expected EOF after %lu "
					       "bytes of image data", 
					  (unsigned long)((*f)->buf.bytesused))
				}

				if (sof) /* (1) */
					goto start_of_frame;

			} else if (eof) {
				DBG(3, "EOF without SOF")
				continue;

			} else {
				PDBGG("Ignoring pointless isochronous frame")
				continue;
			}

		} else if ((*f)->state == F_QUEUED || (*f)->state == F_ERROR) {
start_of_frame:
			(*f)->state = F_GRABBING;
			(*f)->buf.bytesused = 0;
			len -= (sof - pos);
			pos = sof;
			DBG(3, "SOF detected: new video frame")
			if (len)
				goto redo;

		} else if ((*f)->state == F_GRABBING) {
			eof = sn9c102_find_eof_header(cam, pos, len);
			if (eof && eof < sof)
				goto end_of_frame; /* (1) */
			else {
				if (cam->sensor->pix_format.pixelformat ==
				    V4L2_PIX_FMT_SN9C10X) {
					eof = sof-sizeof(sn9c102_sof_header_t);
					goto end_of_frame;
				} else {
					DBG(3, "SOF before expected EOF after "
					       "%lu bytes of image data", 
					  (unsigned long)((*f)->buf.bytesused))
					goto start_of_frame;
				}
			}
		}
	}

resubmit_urb:
	urb->dev = cam->usbdev;
	err = usb_submit_urb(urb, GFP_ATOMIC);
	if (err < 0 && err != -EPERM) {
		cam->state |= DEV_MISCONFIGURED;
		DBG(1, "usb_submit_urb() failed")
	}

	wake_up_interruptible(&cam->wait_frame);
}


static int sn9c102_start_transfer(struct sn9c102_device* cam)
{
	struct usb_device *udev = cam->usbdev;
	struct urb* urb;
	const unsigned int wMaxPacketSize[] = {0, 128, 256, 384, 512,
	                                       680, 800, 900, 1023};
	const unsigned int psz = wMaxPacketSize[SN9C102_ALTERNATE_SETTING];
	s8 i, j;
	int err = 0;

	for (i = 0; i < SN9C102_URBS; i++) {
		cam->transfer_buffer[i] = kmalloc(SN9C102_ISO_PACKETS * psz,
		                                  GFP_KERNEL);
		if (!cam->transfer_buffer[i]) {
			err = -ENOMEM;
			DBG(1, "Not enough memory")
			goto free_buffers;
		}
	}

	for (i = 0; i < SN9C102_URBS; i++) {
		urb = usb_alloc_urb(SN9C102_ISO_PACKETS, GFP_KERNEL);
		cam->urb[i] = urb;
		if (!urb) {
			err = -ENOMEM;
			DBG(1, "usb_alloc_urb() failed")
			goto free_urbs;
		}
		urb->dev = udev;
		urb->context = cam;
		urb->pipe = usb_rcvisocpipe(udev, 1);
		urb->transfer_flags = URB_ISO_ASAP;
		urb->number_of_packets = SN9C102_ISO_PACKETS;
		urb->complete = sn9c102_urb_complete;
		urb->transfer_buffer = cam->transfer_buffer[i];
		urb->transfer_buffer_length = psz * SN9C102_ISO_PACKETS;
		urb->interval = 1;
		for (j = 0; j < SN9C102_ISO_PACKETS; j++) {
			urb->iso_frame_desc[j].offset = psz * j;
			urb->iso_frame_desc[j].length = psz;
		}
	}

	/* Enable video */
	if (!(cam->reg[0x01] & 0x04)) {
		err = sn9c102_write_reg(cam, cam->reg[0x01] | 0x04, 0x01);
		if (err) {
			err = -EIO;
			DBG(1, "I/O hardware error")
			goto free_urbs;
		}
	}

	err = usb_set_interface(udev, 0, SN9C102_ALTERNATE_SETTING);
	if (err) {
		DBG(1, "usb_set_interface() failed")
		goto free_urbs;
	}

	cam->frame_current = NULL;

	for (i = 0; i < SN9C102_URBS; i++) {
		err = usb_submit_urb(cam->urb[i], GFP_KERNEL);
		if (err) {
			for (j = i-1; j >= 0; j--)
				usb_kill_urb(cam->urb[j]);
			DBG(1, "usb_submit_urb() failed, error %d", err)
			goto free_urbs;
		}
	}

	return 0;

free_urbs:
	for (i = 0; (i < SN9C102_URBS) &&  cam->urb[i]; i++)
		usb_free_urb(cam->urb[i]);

free_buffers:
	for (i = 0; (i < SN9C102_URBS) && cam->transfer_buffer[i]; i++)
		kfree(cam->transfer_buffer[i]);

	return err;
}


static int sn9c102_stop_transfer(struct sn9c102_device* cam)
{
	struct usb_device *udev = cam->usbdev;
	s8 i;
	int err = 0;

	if (cam->state & DEV_DISCONNECTED)
		return 0;

	for (i = SN9C102_URBS-1; i >= 0; i--) {
		usb_kill_urb(cam->urb[i]);
		usb_free_urb(cam->urb[i]);
		kfree(cam->transfer_buffer[i]);
	}

	err = usb_set_interface(udev, 0, 0); /* 0 Mb/s */
	if (err)
		DBG(3, "usb_set_interface() failed")

	return err;
}


static int sn9c102_stream_interrupt(struct sn9c102_device* cam)
{
	int err = 0;

	cam->stream = STREAM_INTERRUPT;
	err = wait_event_timeout(cam->wait_stream,
	                         (cam->stream == STREAM_OFF) ||
	                         (cam->state & DEV_DISCONNECTED),
	                         SN9C102_URB_TIMEOUT);
	if (cam->state & DEV_DISCONNECTED)
		return -ENODEV;
	else if (err) {
		cam->state |= DEV_MISCONFIGURED;
		DBG(1, "The camera is misconfigured. To use it, close and "
		       "open /dev/video%d again.", cam->v4ldev->minor)
		return err;
	}

	return 0;
}

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

static u8 sn9c102_strtou8(const char* buff, size_t len, ssize_t* count)
{
	char str[5];
	char* endp;
	unsigned long val;

	if (len < 4) {
		strncpy(str, buff, len);
		str[len+1] = '\0';
	} else {
		strncpy(str, buff, 4);
		str[4] = '\0';
	}

	val = simple_strtoul(str, &endp, 0);

	*count = 0;
	if (val <= 0xff)
		*count = (ssize_t)(endp - str);
	if ((*count) && (len == *count+1) && (buff[*count] == '\n'))
		*count += 1;

	return (u8)val;
}

/*
   NOTE 1: being inside one of the following methods implies that the v4l
           device exists for sure (see kobjects and reference counters)
   NOTE 2: buffers are PAGE_SIZE long
*/

static ssize_t sn9c102_show_reg(struct class_device* cd, char* buf)
{
	struct sn9c102_device* cam;
	ssize_t count;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	count = sprintf(buf, "%u\n", cam->sysfs.reg);

	up(&sn9c102_sysfs_lock);

	return count;
} 


static ssize_t 
sn9c102_store_reg(struct class_device* cd, const char* buf, size_t len)
{
	struct sn9c102_device* cam;
	u8 index;
	ssize_t count;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	index = sn9c102_strtou8(buf, len, &count);
	if (index > 0x1f || !count) {
		up(&sn9c102_sysfs_lock);
		return -EINVAL;
	}

	cam->sysfs.reg = index;

	DBG(2, "Moved SN9C10X register index to 0x%02X", cam->sysfs.reg)
	DBG(3, "Written bytes: %zd", count)

	up(&sn9c102_sysfs_lock);

	return count;
}


static ssize_t sn9c102_show_val(struct class_device* cd, char* buf)
{
	struct sn9c102_device* cam;
	ssize_t count;
	int val;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	if ((val = sn9c102_read_reg(cam, cam->sysfs.reg)) < 0) {
		up(&sn9c102_sysfs_lock);
		return -EIO;
	}

	count = sprintf(buf, "%d\n", val);

	DBG(3, "Read bytes: %zd", count)

	up(&sn9c102_sysfs_lock);

	return count;
} 


static ssize_t
sn9c102_store_val(struct class_device* cd, const char* buf, size_t len)
{
	struct sn9c102_device* cam;
	u8 value;
	ssize_t count;
	int err;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	value = sn9c102_strtou8(buf, len, &count);
	if (!count) {
		up(&sn9c102_sysfs_lock);
		return -EINVAL;
	}

	err = sn9c102_write_reg(cam, value, cam->sysfs.reg);
	if (err) {
		up(&sn9c102_sysfs_lock);
		return -EIO;
	}

	DBG(2, "Written SN9C10X reg. 0x%02X, val. 0x%02X",
	    cam->sysfs.reg, value)
	DBG(3, "Written bytes: %zd", count)

	up(&sn9c102_sysfs_lock);

	return count;
}


static ssize_t sn9c102_show_i2c_reg(struct class_device* cd, char* buf)
{
	struct sn9c102_device* cam;
	ssize_t count;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	count = sprintf(buf, "%u\n", cam->sysfs.i2c_reg);

	DBG(3, "Read bytes: %zd", count)

	up(&sn9c102_sysfs_lock);

	return count;
}


static ssize_t 
sn9c102_store_i2c_reg(struct class_device* cd, const char* buf, size_t len)
{
	struct sn9c102_device* cam;
	u8 index;
	ssize_t count;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	index = sn9c102_strtou8(buf, len, &count);
	if (!count) {
		up(&sn9c102_sysfs_lock);
		return -EINVAL;
	}

	cam->sysfs.i2c_reg = index;

	DBG(2, "Moved sensor register index to 0x%02X", cam->sysfs.i2c_reg)
	DBG(3, "Written bytes: %zd", count)

	up(&sn9c102_sysfs_lock);

	return count;
}


static ssize_t sn9c102_show_i2c_val(struct class_device* cd, char* buf)
{
	struct sn9c102_device* cam;
	ssize_t count;
	int val;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	if (!(cam->sensor->sysfs_ops & SN9C102_I2C_READ)) {
		up(&sn9c102_sysfs_lock);
		return -ENOSYS;
	}

	if ((val = sn9c102_i2c_read(cam, cam->sysfs.i2c_reg)) < 0) {
		up(&sn9c102_sysfs_lock);
		return -EIO;
	}

	count = sprintf(buf, "%d\n", val);

	DBG(3, "Read bytes: %zd", count)

	up(&sn9c102_sysfs_lock);

	return count;
} 


static ssize_t
sn9c102_store_i2c_val(struct class_device* cd, const char* buf, size_t len)
{
	struct sn9c102_device* cam;
	u8 value;
	ssize_t count;
	int err;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	if (!(cam->sensor->sysfs_ops & SN9C102_I2C_WRITE)) {
		up(&sn9c102_sysfs_lock);
		return -ENOSYS;
	}

	value = sn9c102_strtou8(buf, len, &count);
	if (!count) {
		up(&sn9c102_sysfs_lock);
		return -EINVAL;
	}

	err = sn9c102_i2c_write(cam, cam->sysfs.i2c_reg, value);
	if (err) {
		up(&sn9c102_sysfs_lock);
		return -EIO;
	}

	DBG(2, "Written sensor reg. 0x%02X, val. 0x%02X",
	    cam->sysfs.i2c_reg, value)
	DBG(3, "Written bytes: %zd", count)

	up(&sn9c102_sysfs_lock);

	return count;
}


static ssize_t
sn9c102_store_green(struct class_device* cd, const char* buf, size_t len)
{
	struct sn9c102_device* cam;
	enum sn9c102_bridge bridge;
	ssize_t res = 0;
	u8 value;
	ssize_t count;

	if (down_interruptible(&sn9c102_sysfs_lock))
		return -ERESTARTSYS;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam) {
		up(&sn9c102_sysfs_lock);
		return -ENODEV;
	}

	bridge = cam->bridge;

	up(&sn9c102_sysfs_lock);

	value = sn9c102_strtou8(buf, len, &count);
	if (!count)
		return -EINVAL;

	switch (bridge) {
	case BRIDGE_SN9C101:
	case BRIDGE_SN9C102:
		if (value > 0x0f)
			return -EINVAL;
		if ((res = sn9c102_store_reg(cd, "0x11", 4)) >= 0)
			res = sn9c102_store_val(cd, buf, len);
		break;
	case BRIDGE_SN9C103:
		if (value > 0x7f)
			return -EINVAL;
		if ((res = sn9c102_store_reg(cd, "0x04", 4)) >= 0)
			res = sn9c102_store_val(cd, buf, len);
		break;
	}

	return res;
}


static ssize_t
sn9c102_store_blue(struct class_device* cd, const char* buf, size_t len)
{
	ssize_t res = 0;
	u8 value;
	ssize_t count;

	value = sn9c102_strtou8(buf, len, &count);
	if (!count || value > 0x7f)
		return -EINVAL;

	if ((res = sn9c102_store_reg(cd, "0x06", 4)) >= 0)
		res = sn9c102_store_val(cd, buf, len);

	return res;
}


static ssize_t
sn9c102_store_red(struct class_device* cd, const char* buf, size_t len)
{
	ssize_t res = 0;
	u8 value;
	ssize_t count;

	value = sn9c102_strtou8(buf, len, &count);
	if (!count || value > 0x7f)
		return -EINVAL;

	if ((res = sn9c102_store_reg(cd, "0x05", 4)) >= 0)
		res = sn9c102_store_val(cd, buf, len);

	return res;
}


static ssize_t sn9c102_show_frame_header(struct class_device* cd, char* buf)
{
	struct sn9c102_device* cam;
	ssize_t count;

	cam = video_get_drvdata(to_video_device(cd));
	if (!cam)
		return -ENODEV;

	count = sizeof(cam->sysfs.frame_header);
	memcpy(buf, cam->sysfs.frame_header, count);

	DBG(3, "Frame header, read bytes: %zd", count)

	return count;
} 


static CLASS_DEVICE_ATTR(reg, S_IRUGO | S_IWUSR,
                         sn9c102_show_reg, sn9c102_store_reg);
static CLASS_DEVICE_ATTR(val, S_IRUGO | S_IWUSR,
                         sn9c102_show_val, sn9c102_store_val);
static CLASS_DEVICE_ATTR(i2c_reg, S_IRUGO | S_IWUSR,
                         sn9c102_show_i2c_reg, sn9c102_store_i2c_reg);
static CLASS_DEVICE_ATTR(i2c_val, S_IRUGO | S_IWUSR,
                         sn9c102_show_i2c_val, sn9c102_store_i2c_val);
static CLASS_DEVICE_ATTR(green, S_IWUGO, NULL, sn9c102_store_green);
static CLASS_DEVICE_ATTR(blue, S_IWUGO, NULL, sn9c102_store_blue);
static CLASS_DEVICE_ATTR(red, S_IWUGO, NULL, sn9c102_store_red);
static CLASS_DEVICE_ATTR(frame_header, S_IRUGO,
                         sn9c102_show_frame_header, NULL);


static void sn9c102_create_sysfs(struct sn9c102_device* cam)
{
	struct video_device *v4ldev = cam->v4ldev;

	video_device_create_file(v4ldev, &class_device_attr_reg);
	video_device_create_file(v4ldev, &class_device_attr_val);
	video_device_create_file(v4ldev, &class_device_attr_frame_header);
	if (cam->bridge == BRIDGE_SN9C101 || cam->bridge == BRIDGE_SN9C102)
		video_device_create_file(v4ldev, &class_device_attr_green);
	else if (cam->bridge == BRIDGE_SN9C103) {
		video_device_create_file(v4ldev, &class_device_attr_blue);
		video_device_create_file(v4ldev, &class_device_attr_red);
	}
	if (cam->sensor->sysfs_ops) {
		video_device_create_file(v4ldev, &class_device_attr_i2c_reg);
		video_device_create_file(v4ldev, &class_device_attr_i2c_val);
	}
}

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

static int
sn9c102_set_pix_format(struct sn9c102_device* cam, struct v4l2_pix_format* pix)
{
	int err = 0;

	if (pix->pixelformat == V4L2_PIX_FMT_SN9C10X)
		err += sn9c102_write_reg(cam, cam->reg[0x18] | 0x80, 0x18);
	else
		err += sn9c102_write_reg(cam, cam->reg[0x18] & 0x7f, 0x18);

	return err ? -EIO : 0;
}


static int
sn9c102_set_compression(struct sn9c102_device* cam,
                        struct v4l2_jpegcompression* compression)
{
	int err = 0;

	if (compression->quality == 0)
		err += sn9c102_write_reg(cam, cam->reg[0x17] | 0x01, 0x17);
	else if (compression->quality == 1)
		err += sn9c102_write_reg(cam, cam->reg[0x17] & 0xfe, 0x17);

	return err ? -EIO : 0;
}


static int sn9c102_set_scale(struct sn9c102_device* cam, u8 scale)
{
	u8 r = 0;
	int err = 0;

	if (scale == 1)
		r = cam->reg[0x18] & 0xcf;
	else if (scale == 2) {
		r = cam->reg[0x18] & 0xcf;
		r |= 0x10;
	} else if (scale == 4)
		r = cam->reg[0x18] | 0x20;

	err += sn9c102_write_reg(cam, r, 0x18);
	if (err)
		return -EIO;

	PDBGG("Scaling factor: %u", scale)

	return 0;
}


static int sn9c102_set_crop(struct sn9c102_device* cam, struct v4l2_rect* rect)
{
	struct sn9c102_sensor* s = cam->sensor;
	u8 h_start = (u8)(rect->left - s->cropcap.bounds.left),
	   v_start = (u8)(rect->top - s->cropcap.bounds.top),
	   h_size = (u8)(rect->width / 16),
	   v_size = (u8)(rect->height / 16);
	int err = 0;

	err += sn9c102_write_reg(cam, h_start, 0x12);
	err += sn9c102_write_reg(cam, v_start, 0x13);
	err += sn9c102_write_reg(cam, h_size, 0x15);
	err += sn9c102_write_reg(cam, v_size, 0x16);
	if (err)
		return -EIO;

	PDBGG("h_start, v_start, h_size, v_size, ho_size, vo_size "
	      "%u %u %u %u", h_start, v_start, h_size, v_size)

	return 0;
}


static int sn9c102_init(struct sn9c102_device* cam)
{
	struct sn9c102_sensor* s = cam->sensor;
	struct v4l2_control ctrl;
	struct v4l2_queryctrl *qctrl;
	struct v4l2_rect* rect;
	u8 i = 0, n = 0;
	int err = 0;

	if (!(cam->state & DEV_INITIALIZED)) {
		init_waitqueue_head(&cam->open);
		qctrl = s->qctrl;
		rect = &(s->cropcap.defrect);
	} else { /* use current values */
		qctrl = s->_qctrl;
		rect = &(s->_rect);
	}

	err += sn9c102_set_scale(cam, rect->width / s->pix_format.width);
	err += sn9c102_set_crop(cam, rect);
	if (err)
		return err;

	if (s->init) {
		err = s->init(cam);
		if (err) {
			DBG(3, "Sensor initialization failed")
			return err;
		}
	}

	if (!(cam->state & DEV_INITIALIZED))
		cam->compression.quality =  cam->reg[0x17] & 0x01 ? 0 : 1;
	else
		err += sn9c102_set_compression(cam, &cam->compression);
	err += sn9c102_set_pix_format(cam, &s->pix_format);
	if (s->set_pix_format)
		err += s->set_pix_format(cam, &s->pix_format);
	if (err)
		return err;

	if (s->pix_format.pixelformat == V4L2_PIX_FMT_SN9C10X)
		DBG(3, "Compressed video format is active, quality %d", 
		    cam->compression.quality)
	else
		DBG(3, "Uncompressed video format is active")

	if (s->set_crop)
		if ((err = s->set_crop(cam, rect))) {
			DBG(3, "set_crop() failed")
			return err;
		}

	if (s->set_ctrl) {
		n = sizeof(s->qctrl) / sizeof(s->qctrl[0]);
		for (i = 0; i < n; i++)
			if (s->qctrl[i].id != 0 && 
			    !(s->qctrl[i].flags & V4L2_CTRL_FLAG_DISABLED)) {
				ctrl.id = s->qctrl[i].id;
				ctrl.value = qctrl[i].default_value;
				err = s->set_ctrl(cam, &ctrl);
				if (err) {
					DBG(3, "Set %s control failed",
					    s->qctrl[i].name)
					return err;
				}
				DBG(3, "Image sensor supports '%s' control",
				    s->qctrl[i].name)
			}
	}

	if (!(cam->state & DEV_INITIALIZED)) {
		init_MUTEX(&cam->fileop_sem);
		spin_lock_init(&cam->queue_lock);
		init_waitqueue_head(&cam->wait_frame);
		init_waitqueue_head(&cam->wait_stream);
		cam->nreadbuffers = 2;
		memcpy(s->_qctrl, s->qctrl, sizeof(s->qctrl));
		memcpy(&(s->_rect), &(s->cropcap.defrect), 
		       sizeof(struct v4l2_rect));
		cam->state |= DEV_INITIALIZED;
	}

	DBG(2, "Initialization succeeded")
	return 0;
}


static void sn9c102_release_resources(struct sn9c102_device* cam)
{
	down(&sn9c102_sysfs_lock);

	DBG(2, "V4L2 device /dev/video%d deregistered", cam->v4ldev->minor)
	video_set_drvdata(cam->v4ldev, NULL);
	video_unregister_device(cam->v4ldev);

	up(&sn9c102_sysfs_lock);

	kfree(cam->control_buffer);
}

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

static int sn9c102_open(struct inode* inode, struct file* filp)
{
	struct sn9c102_device* cam;
	int err = 0;

	/*
	   This is the only safe way to prevent race conditions with
	   disconnect
	*/
	if (!down_read_trylock(&sn9c102_disconnect))
		return -ERESTARTSYS;

	cam = video_get_drvdata(video_devdata(filp));

	if (down_interruptible(&cam->dev_sem)) {
		up_read(&sn9c102_disconnect);
		return -ERESTARTSYS;
	}

	if (cam->users) {
		DBG(2, "Device /dev/video%d is busy...", cam->v4ldev->minor)
		if ((filp->f_flags & O_NONBLOCK) ||
		    (filp->f_flags & O_NDELAY)) {
			err = -EWOULDBLOCK;
			goto out;
		}
		up(&cam->dev_sem);
		err = wait_event_interruptible_exclusive(cam->open,
		                                  cam->state & DEV_DISCONNECTED
		                                         || !cam->users);
		if (err) {
			up_read(&sn9c102_disconnect);
			return err;
		}
		if (cam->state & DEV_DISCONNECTED) {
			up_read(&sn9c102_disconnect);
			return -ENODEV;
		}
		down(&cam->dev_sem);
	}


	if (cam->state & DEV_MISCONFIGURED) {
		err = sn9c102_init(cam);
		if (err) {
			DBG(1, "Initialization failed again. "
			       "I will retry on next open().")
			goto out;
		}
		cam->state &= ~DEV_MISCONFIGURED;
	}

	if ((err = sn9c102_start_transfer(cam)))
		goto out;

	filp->private_data = cam;
	cam->users++;
	cam->io = IO_NONE;
	cam->stream = STREAM_OFF;
	cam->nbuffers = 0;
	cam->frame_count = 0;
	sn9c102_empty_framequeues(cam);

	DBG(3, "Video device /dev/video%d is open", cam->v4ldev->minor)

out:
	up(&cam->dev_sem);
	up_read(&sn9c102_disconnect);
	return err;
}


static int sn9c102_release(struct inode* inode, struct file* filp)
{
	struct sn9c102_device* cam = video_get_drvdata(video_devdata(filp));

	down(&cam->dev_sem); /* prevent disconnect() to be called */

	sn9c102_stop_transfer(cam);

	sn9c102_release_buffers(cam);

	if (cam->state & DEV_DISCONNECTED) {
		sn9c102_release_resources(cam);
		up(&cam->dev_sem);
		kfree(cam);
		return 0;
	}

	cam->users--;
	wake_up_interruptible_nr(&cam->open, 1);

	DBG(3, "Video device /dev/video%d closed", cam->v4ldev->minor)

	up(&cam->dev_sem);

	return 0;
}


static ssize_t
sn9c102_read(struct file* filp, char __user * buf, size_t count, loff_t* f_pos)
{
	struct sn9c102_device* cam = video_get_drvdata(video_devdata(filp));
	struct sn9c102_frame_t* f, * i;
	unsigned long lock_flags;
	int err = 0;

	if (down_interruptible(&cam->fileop_sem))
		return -ERESTARTSYS;

	if (cam->state & DEV_DISCONNECTED) {
		DBG(1, "Device not present")
		up(&cam->fileop_sem);
		return -ENODEV;
	}

	if (cam->state & DEV_MISCONFIGURED) {
		DBG(1, "The camera is misconfigured. Close and open it again.")
		up(&cam->fileop_sem);
		return -EIO;
	}

	if (cam->io == IO_MMAP) {
		DBG(3, "Close and open the device again to choose "
		       "the read method")
		up(&cam->fileop_sem);
		return -EINVAL;
	}

	if (cam->io == IO_NONE) {
		if (!sn9c102_request_buffers(cam,cam->nreadbuffers, IO_READ)) {
			DBG(1, "read() failed, not enough memory")
			up(&cam->fileop_sem);
			return -ENOMEM;
		}
		cam->io = IO_READ;
		cam->stream = STREAM_ON;
		sn9c102_queue_unusedframes(cam);
	}

	if (!count) {
		up(&cam->fileop_sem);
		return 0;
	}

	if (list_empty(&cam->outqueue)) {
		if (filp->f_flags & O_NONBLOCK) {
			up(&cam->fileop_sem);
			return -EAGAIN;
		}
		err = wait_event_interruptible
		      ( cam->wait_frame, 
		        (!list_empty(&cam->outqueue)) ||
		        (cam->state & DEV_DISCONNECTED) ||
			(cam->state & DEV_MISCONFIGURED) );
		if (err) {
			up(&cam->fileop_sem);
			return err;
		}
		if (cam->state & DEV_DISCONNECTED) {
			up(&cam->fileop_sem);
			return -ENODEV;
		}
		if (cam->state & DEV_MISCONFIGURED) {
			up(&cam->fileop_sem);
			return -EIO;
		}
	}

	f = list_entry(cam->outqueue.prev, struct sn9c102_frame_t, frame);

	spin_lock_irqsave(&cam->queue_lock, lock_flags);
	list_for_each_entry(i, &cam->outqueue, frame)
		i->state = F_UNUSED;
	INIT_LIST_HEAD(&cam->outqueue);
	spin_unlock_irqrestore(&cam->queue_lock, lock_flags);

	sn9c102_queue_unusedframes(cam);

	if (count > f->buf.bytesused)
		count = f->buf.bytesused;

	if (copy_to_user(buf, f->bufmem, count)) {
		up(&cam->fileop_sem);
		return -EFAULT;
	}
	*f_pos += count;

	PDBGG("Frame #%lu, bytes read: %zu", (unsigned long)f->buf.index,count)

	up(&cam->fileop_sem);

	return count;
}


static unsigned int sn9c102_poll(struct file *filp, poll_table *wait)
{
	struct sn9c102_device* cam = video_get_drvdata(video_devdata(filp));
	unsigned int mask = 0;

	if (down_interruptible(&cam->fileop_sem))
		return POLLERR;

	if (cam->state & DEV_DISCONNECTED) {
		DBG(1, "Device not present")
		goto error;
	}

	if (cam->state & DEV_MISCONFIGURED) {
		DBG(1, "The camera is misconfigured. Close and open it again.")
		goto error;
	}

	if (cam->io == IO_NONE) {
		if (!sn9c102_request_buffers(cam, cam->nreadbuffers,
		                             IO_READ)) {
			DBG(1, "poll() failed, not enough memory")
			goto error;
		}
		cam->io = IO_READ;
		cam->stream = STREAM_ON;
	}

	if (cam->io == IO_READ)
		sn9c102_queue_unusedframes(cam);

	poll_wait(filp, &cam->wait_frame, wait);

	if (!list_empty(&cam->outqueue))
		mask |= POLLIN | POLLRDNORM;

	up(&cam->fileop_sem);

	return mask;

error:
	up(&cam->fileop_sem);
	return POLLERR;
}


static void sn9c102_vm_open(struct vm_area_struct* vma)
{
	struct sn9c102_frame_t* f = vma->vm_private_data;
	f->vma_use_count++;
}


static void sn9c102_vm_close(struct vm_area_struct* vma)
{
	/* NOTE: buffers are not freed here */
	struct sn9c102_frame_t* f = vma->vm_private_data;
	f->vma_use_count--;
}


static struct vm_operations_struct sn9c102_vm_ops = {
	.open = sn9c102_vm_open,
	.close = sn9c102_vm_close,
};


static int sn9c102_mmap(struct file* filp, struct vm_area_struct *vma)
{
	struct sn9c102_device* cam = video_get_drvdata(video_devdata(filp));
	unsigned long size = vma->vm_end - vma->vm_start,
	              start = vma->vm_start,
	              pos,
	              page;
	u32 i;

	if (down_interruptible(&cam->fileop_sem))
		return -ERESTARTSYS;

	if (cam->state & DEV_DISCONNECTED) {
		DBG(1, "Device not present")
		up(&cam->fileop_sem);
		return -ENODEV;
	}

	if (cam->state & DEV_MISCONFIGURED) {
		DBG(1, "The camera is misconfigured. Close and open it again.")
		up(&cam->fileop_sem);
		return -EIO;
	}

	if (cam->io != IO_MMAP || !(vma->vm_flags & VM_WRITE) ||
	    size != PAGE_ALIGN(cam->frame[0].buf.length)) {
		up(&cam->fileop_sem);
		return -EINVAL;
	}

	for (i = 0; i < cam->nbuffers; i++) {
		if ((cam->frame[i].buf.m.offset>>PAGE_SHIFT) == vma->vm_pgoff)
			break;
	}
	if (i == cam->nbuffers) {
		up(&cam->fileop_sem);
		return -EINVAL;
	}

	/* VM_IO is eventually going to replace PageReserved altogether */
	vma->vm_flags |= VM_IO;
	vma->vm_flags |= VM_RESERVED; /* avoid to swap out this VMA */

	pos = (unsigned long)cam->frame[i].bufmem;
	while (size > 0) { /* size is page-aligned */
		page = vmalloc_to_pfn((void *)pos);
		if (remap_pfn_range(vma, start, page, PAGE_SIZE,
		                    vma->vm_page_prot)) {
			up(&cam->fileop_sem);
			return -EAGAIN;
		}
		start += PAGE_SIZE;
		pos += PAGE_SIZE;
		size -= PAGE_SIZE;
	}

	vma->vm_ops = &sn9c102_vm_ops;
	vma->vm_private_data = &cam->frame[i];

	sn9c102_vm_open(vma);

	up(&cam->fileop_sem);

	return 0;
}


static int sn9c102_ioctl_v4l2(struct inode* inode, struct file* filp,
                              unsigned int cmd, void __user * arg)
{
	struct sn9c102_device* cam = video_get_drvdata(video_devdata(filp));

	switch (cmd) {

	case VIDIOC_QUERYCAP:
	{
		struct v4l2_capability cap = {
			.driver = "sn9c102",
			.version = SN9C102_MODULE_VERSION_CODE,
			.capabilities = V4L2_CAP_VIDEO_CAPTURE | 
			                V4L2_CAP_READWRITE |
			                V4L2_CAP_STREAMING,
		};

		strlcpy(cap.card, cam->v4ldev->name, sizeof(cap.card));
		if (usb_make_path(cam->usbdev, cap.bus_info,
		    sizeof(cap.bus_info)) < 0)
			strlcpy(cap.bus_info, cam->dev.bus_id,
			        sizeof(cap.bus_info));

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

		return 0;
	}

	case VIDIOC_ENUMINPUT:
	{
		struct v4l2_input i;

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

		if (i.index)
			return -EINVAL;

		memset(&i, 0, sizeof(i));
		strcpy(i.name, "USB");

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

		return 0;
	}

	case VIDIOC_G_INPUT:
	case VIDIOC_S_INPUT:
	{
		int index;

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

		if (index != 0)
			return -EINVAL;

		return 0;
	}

	case VIDIOC_QUERYCTRL:
	{
		struct sn9c102_sensor* s = cam->sensor;
		struct v4l2_queryctrl qc;
		u8 i, n;

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

		n = sizeof(s->qctrl) / sizeof(s->qctrl[0]);
		for (i = 0; i < n; i++)
			if (qc.id && qc.id == s->qctrl[i].id) {
				memcpy(&qc, &(s->qctrl[i]), sizeof(qc));
				if (copy_to_user(arg, &qc, sizeof(qc)))
					return -EFAULT;
				return 0;
			}

		return -EINVAL;
	}

	case VIDIOC_G_CTRL:
	{
		struct sn9c102_sensor* s = cam->sensor;
		struct v4l2_control ctrl;
		int err = 0;

		if (!s->get_ctrl)
			return -EINVAL;

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

		err = s->get_ctrl(cam, &ctrl);

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

		return err;
	}

	case VIDIOC_S_CTRL_OLD:
	case VIDIOC_S_CTRL:
	{
		struct sn9c102_sensor* s = cam->sensor;
		struct v4l2_control ctrl;
		u8 i, n;
		int err = 0;

		if (!s->set_ctrl)
			return -EINVAL;

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

		n = sizeof(s->qctrl) / sizeof(s->qctrl[0]);
		for (i = 0; i < n; i++)
			if (ctrl.id == s->qctrl[i].id) {
				if (ctrl.value < s->qctrl[i].minimum ||
				    ctrl.value > s->qctrl[i].maximum)
					return -ERANGE;
				ctrl.value -= ctrl.value % s->qctrl[i].step;
				break;
			}

		if ((err = s->set_ctrl(cam, &ctrl)))
			return err;

		s->_qctrl[i].default_value = ctrl.value;

		PDBGG("VIDIOC_S_CTRL: id %lu, value %lu",
		      (unsigned long)ctrl.id, (unsigned long)ctrl.value)

		return 0;
	}

	case VIDIOC_CROPCAP:
	{
		struct v4l2_cropcap* cc = &(cam->sensor->cropcap);

		cc->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		cc->pixelaspect.numerator = 1;
		cc->pixelaspect.denominator = 1;

		if (copy_to_user(arg, cc, sizeof(*cc)))
			return -EFAULT;

		return 0;
	}

	case VIDIOC_G_CROP:
	{
		struct sn9c102_sensor* s = cam->sensor;
		struct v4l2_crop crop = {
			.type = V4L2_BUF_TYPE_VIDEO_CAPTURE,
		};

		memcpy(&(crop.c), &(s->_rect), sizeof(struct v4l2_rect));

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

		return 0;
	}

	case VIDIOC_S_CROP:
	{
		struct sn9c102_sensor* s = cam->sensor;
		struct v4l2_crop crop;
		struct v4l2_rect* rect;
		struct v4l2_rect* bounds = &(s->cropcap.bounds);
		struct v4l2_pix_format* pix_format = &(s->pix_format);
		u8 scale;
		const enum sn9c102_stream_state stream = cam->stream;
		const u32 nbuffers = cam->nbuffers;
		u32 i;
		int err = 0;

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

		rect = &(crop.c);

		if (crop.type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
			return -EINVAL;

		if (cam->module_param.force_munmap)
			for (i = 0; i < cam->nbuffers; i++)
				if (cam->frame[i].vma_use_count) {
					DBG(3, "VIDIOC_S_CROP failed. "
					       "Unmap the buffers first.")
					return -EINVAL;
				}

		/* Preserve R,G or B origin */
		rect->left = (s->_rect.left & 1L) ?
		             rect->left | 1L : rect->left & ~1L;
		rect->top = (s->_rect.top & 1L) ?
		            rect->top | 1L : rect->top & ~1L;

		if (rect->width < 16)
			rect->width = 16;
		if (rect->height < 16)
			rect->height = 16;
		if (rect->width > bounds->width)
			rect->width = bounds->width;
		if (rect->height > bounds->height)
			rect->height = bounds->height;
		if (rect->left < bounds->left)
			rect->left = bounds->left;
		if (rect->top < bounds->top)
			rect->top = bounds->top;
		if (rect->left + rect->width > bounds->left + bounds->width)
			rect->left = bounds->left+bounds->width - rect->width;
		if (rect->top + rect->height > bounds->top + bounds->height)
			rect->top = bounds->top+bounds->height - rect->height;

		rect->width &= ~15L;
		rect->height &= ~15L;

		if (SN9C102_PRESERVE_IMGSCALE) {
			/* Calculate the actual scaling factor */
			u32 a, b;
			a = rect->width * rect->height;
			b = pix_format->width * pix_format->height;
			scale = b ? (u8)((a / b) < 4 ? 1 :
		                        ((a / b) < 16 ? 2 : 4)) : 1;
		} else
			scale = 1;

		if (cam->stream == STREAM_ON)
			if ((err = sn9c102_stream_interrupt(cam)))
				return err;

		if (copy_to_user(arg, &crop, sizeof(crop))) {
			cam->stream = stream;
			return -EFAULT;
		}

		if (cam->module_param.force_munmap || cam->io == IO_READ)
			sn9c102_release_buffers(cam);

		err = sn9c102_set_crop(cam, rect);
		if (s->set_crop)
			err += s->set_crop(cam, rect);
		err += sn9c102_set_scale(cam, scale);

		if (err) { /* atomic, no rollback in ioctl() */
			cam->state |= DEV_MISCONFIGURED;
			DBG(1, "VIDIOC_S_CROP failed because of hardware "
			       "problems. To use the camera, close and open "
			       "/dev/video%d again.", cam->v4ldev->minor)
			return -EIO;
		}

		s->pix_format.width = rect->width/scale;
		s->pix_format.height = rect->height/scale;
		memcpy(&(s->_rect), rect, sizeof(*rect));

		if ((cam->module_param.force_munmap || cam->io == IO_READ) &&
		    nbuffers != sn9c102_request_buffers(cam, nbuffers,
		                                        cam->io)) {
			cam->state |= DEV_MISCONFIGURED;
			DBG(1, "VIDIOC_S_CROP failed because of not enough "
			       "memory. To use the camera, close and open "
			       "/dev/video%d again.", cam->v4ldev->minor)
			return -ENOMEM;
		}

		cam->stream = stream;

		return 0;
	}

	case VIDIOC_ENUM_FMT:
	{
		struct v4l2_fmtdesc fmtd;

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

		if (fmtd.index == 0) {
			strcpy(fmtd.description, "bayer rgb");
			fmtd.pixelformat = V4L2_PIX_FMT_SBGGR8;
		} else if (fmtd.index == 1) {
			strcpy(fmtd.description, "compressed");
			fmtd.pixelformat = V4L2_PIX_FMT_SN9C10X;
			fmtd.flags = V4L2_FMT_FLAG_COMPRESSED;
		} else
			return -EINVAL;

		fmtd.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		memset(&fmtd.reserved, 0, sizeof(fmtd.reserved));

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

		return 0;
	}

	case VIDIOC_G_FMT:
	{
		struct v4l2_format format;
		struct v4l2_pix_format* pfmt = &(cam->sensor->pix_format);

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

		if (format.type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
			return -EINVAL;

		pfmt->bytesperline = (pfmt->pixelformat==V4L2_PIX_FMT_SN9C10X)
		                     ? 0 : (pfmt->width * pfmt->priv) / 8;
		pfmt->sizeimage = pfmt->height * ((pfmt->width*pfmt->priv)/8);
		pfmt->field = V4L2_FIELD_NONE;
		memcpy(&(format.fmt.pix), pfmt, sizeof(*pfmt));

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

		return 0;
	}

	case VIDIOC_TRY_FMT:
	case VIDIOC_S_FMT:
	{
		struct sn9c102_sensor* s = cam->sensor;
		struct v4l2_format format;
		struct v4l2_pix_format* pix;
		struct v4l2_pix_format* pfmt = &(s->pix_format);
		struct v4l2_rect* bounds = &(s->cropcap.bounds);
		struct v4l2_rect rect;
		u8 scale;
		const enum sn9c102_stream_state stream = cam->stream;
		const u32 nbuffers = cam->nbuffers;
		u32 i;
		int err = 0;

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

		pix = &(format.fmt.pix);

		if (format.type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
			return -EINVAL;

		memcpy(&rect, &(s->_rect), sizeof(rect));

		{ /* calculate the actual scaling factor */
			u32 a, b;
			a = rect.width * rect.height;
			b = pix->width * pix->height;
			scale = b ? (u8)((a / b) < 4 ? 1 :
		                        ((a / b) < 16 ? 2 : 4)) : 1;
		}

		rect.width = scale * pix->width;
		rect.height = scale * pix->height;

		if (rect.width < 16)
			rect.width = 16;
		if (rect.height < 16)
			rect.height = 16;
		if (rect.width > bounds->left + bounds->width - rect.left)
			rect.width = bounds->left + bounds->width - rect.left;
		if (rect.height > bounds->top + bounds->height - rect.top)
			rect.height = bounds->top + bounds->height - rect.top;

		rect.width &= ~15L;
		rect.height &= ~15L;

		{ /* adjust the scaling factor */
			u32 a, b;
			a = rect.width * rect.height;
			b = pix->width * pix->height;
			scale = b ? (u8)((a / b) < 4 ? 1 :
		                        ((a / b) < 16 ? 2 : 4)) : 1;
		}

		pix->width = rect.width / scale;
		pix->height = rect.height / scale;

		if (pix->pixelformat != V4L2_PIX_FMT_SN9C10X &&
		    pix->pixelformat != V4L2_PIX_FMT_SBGGR8)
			pix->pixelformat = pfmt->pixelformat;
		pix->priv = pfmt->priv; /* bpp */
		pix->colorspace = pfmt->colorspace;
		pix->bytesperline = (pix->pixelformat == V4L2_PIX_FMT_SN9C10X)
		                    ? 0 : (pix->width * pix->priv) / 8;
		pix->sizeimage = pix->height * ((pix->width * pix->priv) / 8);
		pix->field = V4L2_FIELD_NONE;

		if (cmd == VIDIOC_TRY_FMT) {
			if (copy_to_user(arg, &format, sizeof(format)))
				return -EFAULT;
			return 0;
		}

		if (cam->module_param.force_munmap)
			for (i = 0; i < cam->nbuffers; i++)
				if (cam->frame[i].vma_use_count) {
					DBG(3, "VIDIOC_S_FMT failed. "
					       "Unmap the buffers first.")
					return -EINVAL;
				}

		if (cam->stream == STREAM_ON)
			if ((err = sn9c102_stream_interrupt(cam)))
				return err;

		if (copy_to_user(arg, &format, sizeof(format))) {
			cam->stream = stream;
			return -EFAULT;
		}

		if (cam->module_param.force_munmap  || cam->io == IO_READ)
			sn9c102_release_buffers(cam);

		err += sn9c102_set_pix_format(cam, pix);
		err += sn9c102_set_crop(cam, &rect);
		if (s->set_pix_format)
			err += s->set_pix_format(cam, pix);
		if (s->set_crop)
			err += s->set_crop(cam, &rect);
		err += sn9c102_set_scale(cam, scale);

		if (err) { /* atomic, no rollback in ioctl() */
			cam->state |= DEV_MISCONFIGURED;
			DBG(1, "VIDIOC_S_FMT failed because of hardware "
			       "problems. To use the camera, close and open "
			       "/dev/video%d again.", cam->v4ldev->minor)
			return -EIO;
		}

		memcpy(pfmt, pix, sizeof(*pix));
		memcpy(&(s->_rect), &rect, sizeof(rect));

		if ((cam->module_param.force_munmap  || cam->io == IO_READ) &&
		    nbuffers != sn9c102_request_buffers(cam, nbuffers,
		                                        cam->io)) {
			cam->state |= DEV_MISCONFIGURED;
			DBG(1, "VIDIOC_S_FMT failed because of not enough "
			       "memory. To use the camera, close and open "
			       "/dev/video%d again.", cam->v4ldev->minor)
			return -ENOMEM;
		}

		cam->stream = stream;

		return 0;
	}

	case VIDIOC_G_JPEGCOMP:
	{
		if (copy_to_user(arg, &cam->compression,
		                 sizeof(cam->compression)))
			return -EFAULT;

		return 0;
	}

	case VIDIOC_S_JPEGCOMP:
	{
		struct v4l2_jpegcompression jc;
		const enum sn9c102_stream_state stream = cam->stream;
		int err = 0;

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

		if (jc.quality != 0 && jc.quality != 1)
			return -EINVAL;

		if (cam->stream == STREAM_ON)
			if ((err = sn9c102_stream_interrupt(cam)))
				return err;

		err += sn9c102_set_compression(cam, &jc);
		if (err) { /* atomic, no rollback in ioctl() */
			cam->state |= DEV_MISCONFIGURED;
			DBG(1, "VIDIOC_S_JPEGCOMP failed because of hardware "
			       "problems. To use the camera, close and open "
			       "/dev/video%d again.", cam->v4ldev->minor)
			return -EIO;
		}

		cam->compression.quality = jc.quality;

		cam->stream = stream;

		return 0;
	}

	case VIDIOC_REQBUFS:
	{
		struct v4l2_requestbuffers rb;
		u32 i;
		int err;

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

		if (rb.type != V4L2_BUF_TYPE_VIDEO_CAPTURE ||
		    rb.memory != V4L2_MEMORY_MMAP)
			return -EINVAL;

		if (cam->io == IO_READ) {
			DBG(3, "Close and open the device again to choose "
			       "the mmap I/O method")
			return -EINVAL;
		}

		for (i = 0; i < cam->nbuffers; i++)
			if (cam->frame[i].vma_use_count) {
				DBG(3, "VIDIOC_REQBUFS failed. "
				       "Previous buffers are still mapped.")
				return -EINVAL;
			}

		if (cam->stream == STREAM_ON)
			if ((err = sn9c102_stream_interrupt(cam)))
				return err;

		sn9c102_empty_framequeues(cam);

		sn9c102_release_buffers(cam);
		if (rb.count)
			rb.count = sn9c102_request_buffers(cam, rb.count,
			                                   IO_MMAP);

		if (copy_to_user(arg, &rb, sizeof(rb))) {
			sn9c102_release_buffers(cam);
			cam->io = IO_NONE;
			return -EFAULT;
		}

		cam->io = rb.count ? IO_MMAP : IO_NONE;

		return 0;
	}

	case VIDIOC_QUERYBUF:
	{
		struct v4l2_buffer b;

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

		if (b.type != V4L2_BUF_TYPE_VIDEO_CAPTURE ||
		    b.index >= cam->nbuffers || cam->io != IO_MMAP)
			return -EINVAL;

		memcpy(&b, &cam->frame[b.index].buf, sizeof(b));

		if (cam->frame[b.index].vma_use_count)
			b.flags |= V4L2_BUF_FLAG_MAPPED;

		if (cam->frame[b.index].state == F_DONE)
			b.flags |= V4L2_BUF_FLAG_DONE;
		else if (cam->frame[b.index].state != F_UNUSED)
			b.flags |= V4L2_BUF_FLAG_QUEUED;

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

		return 0;
	}

	case VIDIOC_QBUF:
	{
		struct v4l2_buffer b;
		unsigned long lock_flags;

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

		if (b.type != V4L2_BUF_TYPE_VIDEO_CAPTURE ||
		    b.index >= cam->nbuffers || cam->io != IO_MMAP)
			return -EINVAL;

		if (cam->frame[b.index].state != F_UNUSED)
			return -EINVAL;

		cam->frame[b.index].state = F_QUEUED;

		spin_lock_irqsave(&cam->queue_lock, lock_flags);
		list_add_tail(&cam->frame[b.index].frame, &cam->inqueue);
		spin_unlock_irqrestore(&cam->queue_lock, lock_flags);

		PDBGG("Frame #%lu queued", (unsigned long)b.index)

		return 0;
	}

	case VIDIOC_DQBUF:
	{
		struct v4l2_buffer b;
		struct sn9c102_frame_t *f;
		unsigned long lock_flags;
		int err = 0;

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

		if (b.type != V4L2_BUF_TYPE_VIDEO_CAPTURE || cam->io!= IO_MMAP)
			return -EINVAL;

		if (list_empty(&cam->outqueue)) {
			if (cam->stream == STREAM_OFF)
				return -EINVAL;
			if (filp->f_flags & O_NONBLOCK)
				return -EAGAIN;
			err = wait_event_interruptible
			      ( cam->wait_frame, 
			        (!list_empty(&cam->outqueue)) ||
			        (cam->state & DEV_DISCONNECTED) ||
			        (cam->state & DEV_MISCONFIGURED) );
			if (err)
				return err;
			if (cam->state & DEV_DISCONNECTED)
				return -ENODEV;
			if (cam->state & DEV_MISCONFIGURED)
				return -EIO;
		}

		spin_lock_irqsave(&cam->queue_lock, lock_flags);
		f = list_entry(cam->outqueue.next, struct sn9c102_frame_t,
		               frame);
		list_del(cam->outqueue.next);
		spin_unlock_irqrestore(&cam->queue_lock, lock_flags);

		f->state = F_UNUSED;

		memcpy(&b, &f->buf, sizeof(b));
		if (f->vma_use_count)
			b.flags |= V4L2_BUF_FLAG_MAPPED;

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

		PDBGG("Frame #%lu dequeued", (unsigned long)f->buf.index)

		return 0;
	}

	case VIDIOC_STREAMON:
	{
		int type;

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

		if (type != V4L2_BUF_TYPE_VIDEO_CAPTURE || cam->io != IO_MMAP)
			return -EINVAL;

		if (list_empty(&cam->inqueue))
			return -EINVAL;

		cam->stream = STREAM_ON;

		DBG(3, "Stream on")

		return 0;
	}

	case VIDIOC_STREAMOFF:
	{
		int type, err;

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

		if (type != V4L2_BUF_TYPE_VIDEO_CAPTURE || cam->io != IO_MMAP)
			return -EINVAL;

		if (cam->stream == STREAM_ON)
			if ((err = sn9c102_stream_interrupt(cam)))
				return err;

		sn9c102_empty_framequeues(cam);

		DBG(3, "Stream off")

		return 0;
	}

	case VIDIOC_G_PARM:
	{
		struct v4l2_streamparm sp;

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

		if (sp.type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
			return -EINVAL;

		sp.parm.capture.extendedmode = 0;
		sp.parm.capture.readbuffers = cam->nreadbuffers;

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

		return 0;
	}

	case VIDIOC_S_PARM_OLD:
	case VIDIOC_S_PARM:
	{
		struct v4l2_streamparm sp;

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

		if (sp.type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
			return -EINVAL;

		sp.parm.capture.extendedmode = 0;

		if (sp.parm.capture.readbuffers == 0)
			sp.parm.capture.readbuffers = cam->nreadbuffers;

		if (sp.parm.capture.readbuffers > SN9C102_MAX_FRAMES)
			sp.parm.capture.readbuffers = SN9C102_MAX_FRAMES;

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

		cam->nreadbuffers = sp.parm.capture.readbuffers;

		return 0;
	}

	case VIDIOC_G_STD:
	case VIDIOC_S_STD:
	case VIDIOC_QUERYSTD:
	case VIDIOC_ENUMSTD:
	case VIDIOC_QUERYMENU:
		return -EINVAL;

	default:
		return -EINVAL;

	}
}


static int sn9c102_ioctl(struct inode* inode, struct file* filp,
                         unsigned int cmd, unsigned long arg)
{
	struct sn9c102_device* cam = video_get_drvdata(video_devdata(filp));
	int err = 0;

	if (down_interruptible(&cam->fileop_sem))
		return -ERESTARTSYS;

	if (cam->state & DEV_DISCONNECTED) {
		DBG(1, "Device not present")
		up(&cam->fileop_sem);
		return -ENODEV;
	}

	if (cam->state & DEV_MISCONFIGURED) {
		DBG(1, "The camera is misconfigured. Close and open it again.")
		up(&cam->fileop_sem);
		return -EIO;
	}

	err = sn9c102_ioctl_v4l2(inode, filp, cmd, (void __user *)arg);

	up(&cam->fileop_sem);

	return err;
}


static struct file_operations sn9c102_fops = {
	.owner =   THIS_MODULE,
	.open =    sn9c102_open,
	.release = sn9c102_release,
	.ioctl =   sn9c102_ioctl,
	.read =    sn9c102_read,
	.poll =    sn9c102_poll,
	.mmap =    sn9c102_mmap,
	.llseek =  no_llseek,
};

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

/* It exists a single interface only. We do not need to validate anything. */
static int
sn9c102_usb_probe(struct usb_interface* intf, const struct usb_device_id* id)
{
	struct usb_device *udev = interface_to_usbdev(intf);
	struct sn9c102_device* cam;
	static unsigned int dev_nr = 0;
	unsigned int i, n;
	int err = 0, r;

	n = sizeof(sn9c102_id_table)/sizeof(sn9c102_id_table[0]);
	for (i = 0; i < n-1; i++)
		if (le16_to_cpu(udev->descriptor.idVendor) == 
		    sn9c102_id_table[i].idVendor &&
		    le16_to_cpu(udev->descriptor.idProduct) ==
		    sn9c102_id_table[i].idProduct)
			break;
	if (i == n-1)
		return -ENODEV;

	if (!(cam = kmalloc(sizeof(struct sn9c102_device), GFP_KERNEL)))
		return -ENOMEM;
	memset(cam, 0, sizeof(*cam));

	cam->usbdev = udev;

	memcpy(&cam->dev, &udev->dev, sizeof(struct device));

	if (!(cam->control_buffer = kmalloc(8, GFP_KERNEL))) {
		DBG(1, "kmalloc() failed")
		err = -ENOMEM;
		goto fail;
	}
	memset(cam->control_buffer, 0, 8);

	if (!(cam->v4ldev = video_device_alloc())) {
		DBG(1, "video_device_alloc() failed")
		err = -ENOMEM;
		goto fail;
	}

	init_MUTEX(&cam->dev_sem);

	r = sn9c102_read_reg(cam, 0x00);
	if (r < 0 || r != 0x10) {
		DBG(1, "Sorry, this is not a SN9C10x based camera "
		       "(vid/pid 0x%04X/0x%04X)",
		    sn9c102_id_table[i].idVendor,sn9c102_id_table[i].idProduct)
		err = -ENODEV;
		goto fail;
	}

	cam->bridge = (sn9c102_id_table[i].idProduct & 0xffc0) == 0x6080 ?
	              BRIDGE_SN9C103 : BRIDGE_SN9C102;
	switch (cam->bridge) {
	case BRIDGE_SN9C101:
	case BRIDGE_SN9C102:
		DBG(2, "SN9C10[12] PC Camera Controller detected "
		       "(vid/pid 0x%04X/0x%04X)", sn9c102_id_table[i].idVendor,
		    sn9c102_id_table[i].idProduct)
		break;
	case BRIDGE_SN9C103:
		DBG(2, "SN9C103 PC Camera Controller detected "
		       "(vid/pid 0x%04X/0x%04X)", sn9c102_id_table[i].idVendor,
		    sn9c102_id_table[i].idProduct)
		break;
	}

	for  (i = 0; sn9c102_sensor_table[i]; i++) {
		err = sn9c102_sensor_table[i](cam);
		if (!err)
			break;
	}

	if (!err && cam->sensor) {
		DBG(2, "%s image sensor detected", cam->sensor->name)
		DBG(3, "Support for %s maintained by %s",
		    cam->sensor->name, cam->sensor->maintainer)
	} else {
		DBG(1, "No supported image sensor detected")
		err = -ENODEV;
		goto fail;
	}

	if (sn9c102_init(cam)) {
		DBG(1, "Initialization failed. I will retry on open().")
		cam->state |= DEV_MISCONFIGURED;
	}

	strcpy(cam->v4ldev->name, "SN9C10x PC Camera");
	cam->v4ldev->owner = THIS_MODULE;
	cam->v4ldev->type = VID_TYPE_CAPTURE | VID_TYPE_SCALES;
	cam->v4ldev->hardware = VID_HARDWARE_SN9C102;
	cam->v4ldev->fops = &sn9c102_fops;
	cam->v4ldev->minor = video_nr[dev_nr];
	cam->v4ldev->release = video_device_release;
	video_set_drvdata(cam->v4ldev, cam);

	down(&cam->dev_sem);

	err = video_register_device(cam->v4ldev, VFL_TYPE_GRABBER,
	                            video_nr[dev_nr]);
	if (err) {
		DBG(1, "V4L2 device registration failed")
		if (err == -ENFILE && video_nr[dev_nr] == -1)
			DBG(1, "Free /dev/videoX node not found")
		video_nr[dev_nr] = -1;
		dev_nr = (dev_nr < SN9C102_MAX_DEVICES-1) ? dev_nr+1 : 0;
		up(&cam->dev_sem);
		goto fail;
	}

	DBG(2, "V4L2 device registered as /dev/video%d", cam->v4ldev->minor)

	cam->module_param.force_munmap = force_munmap[dev_nr];

	dev_nr = (dev_nr < SN9C102_MAX_DEVICES-1) ? dev_nr+1 : 0;

	sn9c102_create_sysfs(cam);
	DBG(2, "Optional device control through 'sysfs' interface ready")

	usb_set_intfdata(intf, cam);

	up(&cam->dev_sem);

	return 0;

fail:
	if (cam) {
		kfree(cam->control_buffer);
		if (cam->v4ldev)
			video_device_release(cam->v4ldev);
		kfree(cam);
	}
	return err;
}


static void sn9c102_usb_disconnect(struct usb_interface* intf)
{
	struct sn9c102_device* cam = usb_get_intfdata(intf);

	if (!cam)
		return;

	down_write(&sn9c102_disconnect);

	down(&cam->dev_sem); 

	DBG(2, "Disconnecting %s...", cam->v4ldev->name)

	wake_up_interruptible_all(&cam->open);

	if (cam->users) {
		DBG(2, "Device /dev/video%d is open! Deregistration and "
		       "memory deallocation are deferred on close.",
		    cam->v4ldev->minor)
		cam->state |= DEV_MISCONFIGURED;
		sn9c102_stop_transfer(cam);
		cam->state |= DEV_DISCONNECTED;
		wake_up_interruptible(&cam->wait_frame);
		wake_up_interruptible(&cam->wait_stream);
	} else {
		cam->state |= DEV_DISCONNECTED;
		sn9c102_release_resources(cam);
	}

	up(&cam->dev_sem);

	if (!cam->users)
		kfree(cam);

	up_write(&sn9c102_disconnect);
}


static struct usb_driver sn9c102_usb_driver = {
	.owner =      THIS_MODULE,
	.name =       "sn9c102",
	.id_table =   sn9c102_id_table,
	.probe =      sn9c102_usb_probe,
	.disconnect = sn9c102_usb_disconnect,
};

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

static int __init sn9c102_module_init(void)
{
	int err = 0;

	KDBG(2, SN9C102_MODULE_NAME " v" SN9C102_MODULE_VERSION)
	KDBG(3, SN9C102_MODULE_AUTHOR)

	if ((err = usb_register(&sn9c102_usb_driver)))
		KDBG(1, "usb_register() failed")

	return err;
}


static void __exit sn9c102_module_exit(void)
{
	usb_deregister(&sn9c102_usb_driver);
}


module_init(sn9c102_module_init);
module_exit(sn9c102_module_exit);