/*
 * stk-webcam.c : Driver for Syntek 1125 USB webcam controller
 *
 * Copyright (C) 2006 Nicolas VIVIEN
 * Copyright 2007-2008 Jaime Velasco Juan <jsagarribay@gmail.com>
 *
 * Some parts are inspired from cafe_ccic.c
 * Copyright 2006-2007 Jonathan Corbet
 *
 * 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
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>

#include <linux/dmi.h>
#include <linux/usb.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/videodev2.h>
#include <media/v4l2-common.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-event.h>

#include "stk-webcam.h"


static int hflip = -1;
module_param(hflip, int, 0444);
MODULE_PARM_DESC(hflip, "Horizontal image flip (mirror). Defaults to 0");

static int vflip = -1;
module_param(vflip, int, 0444);
MODULE_PARM_DESC(vflip, "Vertical image flip. Defaults to 0");

static int debug;
module_param(debug, int, 0444);
MODULE_PARM_DESC(debug, "Debug v4l ioctls. Defaults to 0");

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jaime Velasco Juan <jsagarribay@gmail.com> and Nicolas VIVIEN");
MODULE_DESCRIPTION("Syntek DC1125 webcam driver");

/* Some cameras have audio interfaces, we aren't interested in those */
static const struct usb_device_id stkwebcam_table[] = {
	{ USB_DEVICE_AND_INTERFACE_INFO(0x174f, 0xa311, 0xff, 0xff, 0xff) },
	{ USB_DEVICE_AND_INTERFACE_INFO(0x05e1, 0x0501, 0xff, 0xff, 0xff) },
	{ }
};
MODULE_DEVICE_TABLE(usb, stkwebcam_table);

/*
 * The stk webcam laptop module is mounted upside down in some laptops :(
 *
 * Some background information (thanks to Hans de Goede for providing this):
 *
 * 1) Once upon a time the stkwebcam driver was written
 *
 * 2) The webcam in question was used mostly in Asus laptop models, including
 * the laptop of the original author of the driver, and in these models, in
 * typical Asus fashion (see the long long list for uvc cams inside v4l-utils),
 * they mounted the webcam-module the wrong way up. So the hflip and vflip
 * module options were given a default value of 1 (the correct value for
 * upside down mounted models)
 *
 * 3) Years later I got a bug report from a user with a laptop with stkwebcam,
 * where the module was actually mounted the right way up, and thus showed
 * upside down under Linux. So now I was facing the choice of 2 options:
 *
 * a) Add a not-upside-down list to stkwebcam, which overrules the default.
 *
 * b) Do it like all the other drivers do, and make the default right for
 *    cams mounted the proper way and add an upside-down model list, with
 *    models where we need to flip-by-default.
 *
 * Despite knowing that going b) would cause a period of pain where we were
 * building the table I opted to go for option b), since a) is just too ugly,
 * and worse different from how every other driver does it leading to
 * confusion in the long run. This change was made in kernel 3.6.
 *
 * So for any user report about upside-down images since kernel 3.6 ask them
 * to provide the output of 'sudo dmidecode' so the laptop can be added in
 * the table below.
 */
static const struct dmi_system_id stk_upside_down_dmi_table[] = {
	{
		.ident = "ASUS G1",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "G1")
		}
	}, {
		.ident = "ASUS F3JC",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
			DMI_MATCH(DMI_PRODUCT_NAME, "F3JC")
		}
	},
	{
		.ident = "T12Rg-H",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "HCL Infosystems Limited"),
			DMI_MATCH(DMI_PRODUCT_NAME, "T12Rg-H")
		}
	},
	{}
};


/*
 * Basic stuff
 */
int stk_camera_write_reg(struct stk_camera *dev, u16 index, u8 value)
{
	struct usb_device *udev = dev->udev;
	int ret;

	ret =  usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
			0x01,
			USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
			value,
			index,
			NULL,
			0,
			500);
	if (ret < 0)
		return ret;
	else
		return 0;
}

int stk_camera_read_reg(struct stk_camera *dev, u16 index, u8 *value)
{
	struct usb_device *udev = dev->udev;
	unsigned char *buf;
	int ret;

	buf = kmalloc(sizeof(u8), GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
			0x00,
			USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
			0x00,
			index,
			buf,
			sizeof(u8),
			500);
	if (ret >= 0)
		*value = *buf;

	kfree(buf);

	if (ret < 0)
		return ret;
	else
		return 0;
}

static int stk_start_stream(struct stk_camera *dev)
{
	u8 value;
	int i, ret;
	u8 value_116, value_117;


	if (!is_present(dev))
		return -ENODEV;
	if (!is_memallocd(dev) || !is_initialised(dev)) {
		pr_err("FIXME: Buffers are not allocated\n");
		return -EFAULT;
	}
	ret = usb_set_interface(dev->udev, 0, 5);

	if (ret < 0)
		pr_err("usb_set_interface failed !\n");
	if (stk_sensor_wakeup(dev))
		pr_err("error awaking the sensor\n");

	stk_camera_read_reg(dev, 0x0116, &value_116);
	stk_camera_read_reg(dev, 0x0117, &value_117);

	stk_camera_write_reg(dev, 0x0116, 0x0000);
	stk_camera_write_reg(dev, 0x0117, 0x0000);

	stk_camera_read_reg(dev, 0x0100, &value);
	stk_camera_write_reg(dev, 0x0100, value | 0x80);

	stk_camera_write_reg(dev, 0x0116, value_116);
	stk_camera_write_reg(dev, 0x0117, value_117);
	for (i = 0; i < MAX_ISO_BUFS; i++) {
		if (dev->isobufs[i].urb) {
			ret = usb_submit_urb(dev->isobufs[i].urb, GFP_KERNEL);
			atomic_inc(&dev->urbs_used);
			if (ret)
				return ret;
		}
	}
	set_streaming(dev);
	return 0;
}

static int stk_stop_stream(struct stk_camera *dev)
{
	u8 value;
	int i;
	if (is_present(dev)) {
		stk_camera_read_reg(dev, 0x0100, &value);
		stk_camera_write_reg(dev, 0x0100, value & ~0x80);
		if (dev->isobufs != NULL) {
			for (i = 0; i < MAX_ISO_BUFS; i++) {
				if (dev->isobufs[i].urb)
					usb_kill_urb(dev->isobufs[i].urb);
			}
		}
		unset_streaming(dev);

		if (usb_set_interface(dev->udev, 0, 0))
			pr_err("usb_set_interface failed !\n");
		if (stk_sensor_sleep(dev))
			pr_err("error suspending the sensor\n");
	}
	return 0;
}

/*
 * This seems to be the shortest init sequence we
 * must do in order to find the sensor
 * Bit 5 of reg. 0x0000 here is important, when reset to 0 the sensor
 * is also reset. Maybe powers down it?
 * Rest of values don't make a difference
 */

static struct regval stk1125_initvals[] = {
	/*TODO: What means this sequence? */
	{0x0000, 0x24},
	{0x0100, 0x21},
	{0x0002, 0x68},
	{0x0003, 0x80},
	{0x0005, 0x00},
	{0x0007, 0x03},
	{0x000d, 0x00},
	{0x000f, 0x02},
	{0x0300, 0x12},
	{0x0350, 0x41},
	{0x0351, 0x00},
	{0x0352, 0x00},
	{0x0353, 0x00},
	{0x0018, 0x10},
	{0x0019, 0x00},
	{0x001b, 0x0e},
	{0x001c, 0x46},
	{0x0300, 0x80},
	{0x001a, 0x04},
	{0x0110, 0x00},
	{0x0111, 0x00},
	{0x0112, 0x00},
	{0x0113, 0x00},

	{0xffff, 0xff},
};


static int stk_initialise(struct stk_camera *dev)
{
	struct regval *rv;
	int ret;
	if (!is_present(dev))
		return -ENODEV;
	if (is_initialised(dev))
		return 0;
	rv = stk1125_initvals;
	while (rv->reg != 0xffff) {
		ret = stk_camera_write_reg(dev, rv->reg, rv->val);
		if (ret)
			return ret;
		rv++;
	}
	if (stk_sensor_init(dev) == 0) {
		set_initialised(dev);
		return 0;
	} else
		return -1;
}

/* *********************************************** */
/*
 * This function is called as an URB transfert is complete (Isochronous pipe).
 * So, the traitement is done in interrupt time, so it has be fast, not crash,
 * and not stall. Neat.
 */
static void stk_isoc_handler(struct urb *urb)
{
	int i;
	int ret;
	int framelen;
	unsigned long flags;

	unsigned char *fill = NULL;
	unsigned char *iso_buf = NULL;

	struct stk_camera *dev;
	struct stk_sio_buffer *fb;

	dev = (struct stk_camera *) urb->context;

	if (dev == NULL) {
		pr_err("isoc_handler called with NULL device !\n");
		return;
	}

	if (urb->status == -ENOENT || urb->status == -ECONNRESET
		|| urb->status == -ESHUTDOWN) {
		atomic_dec(&dev->urbs_used);
		return;
	}

	spin_lock_irqsave(&dev->spinlock, flags);

	if (urb->status != -EINPROGRESS && urb->status != 0) {
		pr_err("isoc_handler: urb->status == %d\n", urb->status);
		goto resubmit;
	}

	if (list_empty(&dev->sio_avail)) {
		/*FIXME Stop streaming after a while */
		pr_err_ratelimited("isoc_handler without available buffer!\n");
		goto resubmit;
	}
	fb = list_first_entry(&dev->sio_avail,
			struct stk_sio_buffer, list);
	fill = fb->buffer + fb->v4lbuf.bytesused;

	for (i = 0; i < urb->number_of_packets; i++) {
		if (urb->iso_frame_desc[i].status != 0) {
			if (urb->iso_frame_desc[i].status != -EXDEV)
				pr_err("Frame %d has error %d\n",
				       i, urb->iso_frame_desc[i].status);
			continue;
		}
		framelen = urb->iso_frame_desc[i].actual_length;
		iso_buf = urb->transfer_buffer + urb->iso_frame_desc[i].offset;

		if (framelen <= 4)
			continue; /* no data */

		/*
		 * we found something informational from there
		 * the isoc frames have to type of headers
		 * type1: 00 xx 00 00 or 20 xx 00 00
		 * type2: 80 xx 00 00 00 00 00 00 or a0 xx 00 00 00 00 00 00
		 * xx is a sequencer which has never been seen over 0x3f
		 * imho data written down looks like bayer, i see similarities
		 * after every 640 bytes
		 */
		if (*iso_buf & 0x80) {
			framelen -= 8;
			iso_buf += 8;
			/* This marks a new frame */
			if (fb->v4lbuf.bytesused != 0
				&& fb->v4lbuf.bytesused != dev->frame_size) {
				pr_err_ratelimited("frame %d, bytesused=%d, skipping\n",
						   i, fb->v4lbuf.bytesused);
				fb->v4lbuf.bytesused = 0;
				fill = fb->buffer;
			} else if (fb->v4lbuf.bytesused == dev->frame_size) {
				if (list_is_singular(&dev->sio_avail)) {
					/* Always reuse the last buffer */
					fb->v4lbuf.bytesused = 0;
					fill = fb->buffer;
				} else {
					list_move_tail(dev->sio_avail.next,
						&dev->sio_full);
					wake_up(&dev->wait_frame);
					fb = list_first_entry(&dev->sio_avail,
						struct stk_sio_buffer, list);
					fb->v4lbuf.bytesused = 0;
					fill = fb->buffer;
				}
			}
		} else {
			framelen -= 4;
			iso_buf += 4;
		}

		/* Our buffer is full !!! */
		if (framelen + fb->v4lbuf.bytesused > dev->frame_size) {
			pr_err_ratelimited("Frame buffer overflow, lost sync\n");
			/*FIXME Do something here? */
			continue;
		}
		spin_unlock_irqrestore(&dev->spinlock, flags);
		memcpy(fill, iso_buf, framelen);
		spin_lock_irqsave(&dev->spinlock, flags);
		fill += framelen;

		/* New size of our buffer */
		fb->v4lbuf.bytesused += framelen;
	}

resubmit:
	spin_unlock_irqrestore(&dev->spinlock, flags);
	urb->dev = dev->udev;
	ret = usb_submit_urb(urb, GFP_ATOMIC);
	if (ret != 0) {
		pr_err("Error (%d) re-submitting urb in stk_isoc_handler\n",
		       ret);
	}
}

/* -------------------------------------------- */

static int stk_prepare_iso(struct stk_camera *dev)
{
	void *kbuf;
	int i, j;
	struct urb *urb;
	struct usb_device *udev;

	if (dev == NULL)
		return -ENXIO;
	udev = dev->udev;

	if (dev->isobufs)
		pr_err("isobufs already allocated. Bad\n");
	else
		dev->isobufs = kcalloc(MAX_ISO_BUFS, sizeof(*dev->isobufs),
				       GFP_KERNEL);
	if (dev->isobufs == NULL) {
		pr_err("Unable to allocate iso buffers\n");
		return -ENOMEM;
	}
	for (i = 0; i < MAX_ISO_BUFS; i++) {
		if (dev->isobufs[i].data == NULL) {
			kbuf = kzalloc(ISO_BUFFER_SIZE, GFP_KERNEL);
			if (kbuf == NULL) {
				pr_err("Failed to allocate iso buffer %d\n", i);
				goto isobufs_out;
			}
			dev->isobufs[i].data = kbuf;
		} else
			pr_err("isobuf data already allocated\n");
		if (dev->isobufs[i].urb == NULL) {
			urb = usb_alloc_urb(ISO_FRAMES_PER_DESC, GFP_KERNEL);
			if (urb == NULL)
				goto isobufs_out;
			dev->isobufs[i].urb = urb;
		} else {
			pr_err("Killing URB\n");
			usb_kill_urb(dev->isobufs[i].urb);
			urb = dev->isobufs[i].urb;
		}
		urb->interval = 1;
		urb->dev = udev;
		urb->pipe = usb_rcvisocpipe(udev, dev->isoc_ep);
		urb->transfer_flags = URB_ISO_ASAP;
		urb->transfer_buffer = dev->isobufs[i].data;
		urb->transfer_buffer_length = ISO_BUFFER_SIZE;
		urb->complete = stk_isoc_handler;
		urb->context = dev;
		urb->start_frame = 0;
		urb->number_of_packets = ISO_FRAMES_PER_DESC;

		for (j = 0; j < ISO_FRAMES_PER_DESC; j++) {
			urb->iso_frame_desc[j].offset = j * ISO_MAX_FRAME_SIZE;
			urb->iso_frame_desc[j].length = ISO_MAX_FRAME_SIZE;
		}
	}
	set_memallocd(dev);
	return 0;

isobufs_out:
	for (i = 0; i < MAX_ISO_BUFS && dev->isobufs[i].data; i++)
		kfree(dev->isobufs[i].data);
	for (i = 0; i < MAX_ISO_BUFS && dev->isobufs[i].urb; i++)
		usb_free_urb(dev->isobufs[i].urb);
	kfree(dev->isobufs);
	dev->isobufs = NULL;
	return -ENOMEM;
}

static void stk_clean_iso(struct stk_camera *dev)
{
	int i;

	if (dev == NULL || dev->isobufs == NULL)
		return;

	for (i = 0; i < MAX_ISO_BUFS; i++) {
		struct urb *urb;

		urb = dev->isobufs[i].urb;
		if (urb) {
			if (atomic_read(&dev->urbs_used) && is_present(dev))
				usb_kill_urb(urb);
			usb_free_urb(urb);
		}
		kfree(dev->isobufs[i].data);
	}
	kfree(dev->isobufs);
	dev->isobufs = NULL;
	unset_memallocd(dev);
}

static int stk_setup_siobuf(struct stk_camera *dev, int index)
{
	struct stk_sio_buffer *buf = dev->sio_bufs + index;
	INIT_LIST_HEAD(&buf->list);
	buf->v4lbuf.length = PAGE_ALIGN(dev->frame_size);
	buf->buffer = vmalloc_user(buf->v4lbuf.length);
	if (buf->buffer == NULL)
		return -ENOMEM;
	buf->mapcount = 0;
	buf->dev = dev;
	buf->v4lbuf.index = index;
	buf->v4lbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	buf->v4lbuf.flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
	buf->v4lbuf.field = V4L2_FIELD_NONE;
	buf->v4lbuf.memory = V4L2_MEMORY_MMAP;
	buf->v4lbuf.m.offset = 2*index*buf->v4lbuf.length;
	return 0;
}

static int stk_free_sio_buffers(struct stk_camera *dev)
{
	int i;
	int nbufs;
	unsigned long flags;
	if (dev->n_sbufs == 0 || dev->sio_bufs == NULL)
		return 0;
	/*
	* If any buffers are mapped, we cannot free them at all.
	*/
	for (i = 0; i < dev->n_sbufs; i++) {
		if (dev->sio_bufs[i].mapcount > 0)
			return -EBUSY;
	}
	/*
	* OK, let's do it.
	*/
	spin_lock_irqsave(&dev->spinlock, flags);
	INIT_LIST_HEAD(&dev->sio_avail);
	INIT_LIST_HEAD(&dev->sio_full);
	nbufs = dev->n_sbufs;
	dev->n_sbufs = 0;
	spin_unlock_irqrestore(&dev->spinlock, flags);
	for (i = 0; i < nbufs; i++)
		vfree(dev->sio_bufs[i].buffer);
	kfree(dev->sio_bufs);
	dev->sio_bufs = NULL;
	return 0;
}

static int stk_prepare_sio_buffers(struct stk_camera *dev, unsigned n_sbufs)
{
	int i;
	if (dev->sio_bufs != NULL)
		pr_err("sio_bufs already allocated\n");
	else {
		dev->sio_bufs = kcalloc(n_sbufs,
					sizeof(struct stk_sio_buffer),
					GFP_KERNEL);
		if (dev->sio_bufs == NULL)
			return -ENOMEM;
		for (i = 0; i < n_sbufs; i++) {
			if (stk_setup_siobuf(dev, i))
				return (dev->n_sbufs > 1 ? 0 : -ENOMEM);
			dev->n_sbufs = i+1;
		}
	}
	return 0;
}

static int stk_allocate_buffers(struct stk_camera *dev, unsigned n_sbufs)
{
	int err;
	err = stk_prepare_iso(dev);
	if (err) {
		stk_clean_iso(dev);
		return err;
	}
	err = stk_prepare_sio_buffers(dev, n_sbufs);
	if (err) {
		stk_free_sio_buffers(dev);
		return err;
	}
	return 0;
}

static void stk_free_buffers(struct stk_camera *dev)
{
	stk_clean_iso(dev);
	stk_free_sio_buffers(dev);
}
/* -------------------------------------------- */

/* v4l file operations */

static int v4l_stk_open(struct file *fp)
{
	struct stk_camera *dev = video_drvdata(fp);
	int err;

	if (dev == NULL || !is_present(dev))
		return -ENXIO;

	if (mutex_lock_interruptible(&dev->lock))
		return -ERESTARTSYS;
	if (!dev->first_init)
		stk_camera_write_reg(dev, 0x0, 0x24);
	else
		dev->first_init = 0;

	err = v4l2_fh_open(fp);
	if (!err)
		usb_autopm_get_interface(dev->interface);
	mutex_unlock(&dev->lock);
	return err;
}

static int v4l_stk_release(struct file *fp)
{
	struct stk_camera *dev = video_drvdata(fp);

	mutex_lock(&dev->lock);
	if (dev->owner == fp) {
		stk_stop_stream(dev);
		stk_free_buffers(dev);
		stk_camera_write_reg(dev, 0x0, 0x49); /* turn off the LED */
		unset_initialised(dev);
		dev->owner = NULL;
	}

	usb_autopm_put_interface(dev->interface);
	mutex_unlock(&dev->lock);
	return v4l2_fh_release(fp);
}

static ssize_t stk_read(struct file *fp, char __user *buf,
		size_t count, loff_t *f_pos)
{
	int i;
	int ret;
	unsigned long flags;
	struct stk_sio_buffer *sbuf;
	struct stk_camera *dev = video_drvdata(fp);

	if (!is_present(dev))
		return -EIO;
	if (dev->owner && (!dev->reading || dev->owner != fp))
		return -EBUSY;
	dev->owner = fp;
	if (!is_streaming(dev)) {
		if (stk_initialise(dev)
			|| stk_allocate_buffers(dev, 3)
			|| stk_start_stream(dev))
			return -ENOMEM;
		dev->reading = 1;
		spin_lock_irqsave(&dev->spinlock, flags);
		for (i = 0; i < dev->n_sbufs; i++) {
			list_add_tail(&dev->sio_bufs[i].list, &dev->sio_avail);
			dev->sio_bufs[i].v4lbuf.flags = V4L2_BUF_FLAG_QUEUED;
		}
		spin_unlock_irqrestore(&dev->spinlock, flags);
	}
	if (*f_pos == 0) {
		if (fp->f_flags & O_NONBLOCK && list_empty(&dev->sio_full))
			return -EWOULDBLOCK;
		ret = wait_event_interruptible(dev->wait_frame,
			!list_empty(&dev->sio_full) || !is_present(dev));
		if (ret)
			return ret;
		if (!is_present(dev))
			return -EIO;
	}
	if (count + *f_pos > dev->frame_size)
		count = dev->frame_size - *f_pos;
	spin_lock_irqsave(&dev->spinlock, flags);
	if (list_empty(&dev->sio_full)) {
		spin_unlock_irqrestore(&dev->spinlock, flags);
		pr_err("BUG: No siobufs ready\n");
		return 0;
	}
	sbuf = list_first_entry(&dev->sio_full, struct stk_sio_buffer, list);
	spin_unlock_irqrestore(&dev->spinlock, flags);

	if (copy_to_user(buf, sbuf->buffer + *f_pos, count))
		return -EFAULT;

	*f_pos += count;

	if (*f_pos >= dev->frame_size) {
		*f_pos = 0;
		spin_lock_irqsave(&dev->spinlock, flags);
		list_move_tail(&sbuf->list, &dev->sio_avail);
		spin_unlock_irqrestore(&dev->spinlock, flags);
	}
	return count;
}

static ssize_t v4l_stk_read(struct file *fp, char __user *buf,
		size_t count, loff_t *f_pos)
{
	struct stk_camera *dev = video_drvdata(fp);
	int ret;

	if (mutex_lock_interruptible(&dev->lock))
		return -ERESTARTSYS;
	ret = stk_read(fp, buf, count, f_pos);
	mutex_unlock(&dev->lock);
	return ret;
}

static __poll_t v4l_stk_poll(struct file *fp, poll_table *wait)
{
	struct stk_camera *dev = video_drvdata(fp);
	__poll_t res = v4l2_ctrl_poll(fp, wait);

	poll_wait(fp, &dev->wait_frame, wait);

	if (!is_present(dev))
		return EPOLLERR;

	if (!list_empty(&dev->sio_full))
		return res | EPOLLIN | EPOLLRDNORM;

	return res;
}


static void stk_v4l_vm_open(struct vm_area_struct *vma)
{
	struct stk_sio_buffer *sbuf = vma->vm_private_data;
	sbuf->mapcount++;
}
static void stk_v4l_vm_close(struct vm_area_struct *vma)
{
	struct stk_sio_buffer *sbuf = vma->vm_private_data;
	sbuf->mapcount--;
	if (sbuf->mapcount == 0)
		sbuf->v4lbuf.flags &= ~V4L2_BUF_FLAG_MAPPED;
}
static const struct vm_operations_struct stk_v4l_vm_ops = {
	.open = stk_v4l_vm_open,
	.close = stk_v4l_vm_close
};

static int v4l_stk_mmap(struct file *fp, struct vm_area_struct *vma)
{
	unsigned int i;
	int ret;
	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
	struct stk_camera *dev = video_drvdata(fp);
	struct stk_sio_buffer *sbuf = NULL;

	if (!(vma->vm_flags & VM_WRITE) || !(vma->vm_flags & VM_SHARED))
		return -EINVAL;

	for (i = 0; i < dev->n_sbufs; i++) {
		if (dev->sio_bufs[i].v4lbuf.m.offset == offset) {
			sbuf = dev->sio_bufs + i;
			break;
		}
	}
	if (sbuf == NULL)
		return -EINVAL;
	ret = remap_vmalloc_range(vma, sbuf->buffer, 0);
	if (ret)
		return ret;
	vma->vm_flags |= VM_DONTEXPAND;
	vma->vm_private_data = sbuf;
	vma->vm_ops = &stk_v4l_vm_ops;
	sbuf->v4lbuf.flags |= V4L2_BUF_FLAG_MAPPED;
	stk_v4l_vm_open(vma);
	return 0;
}

/* v4l ioctl handlers */

static int stk_vidioc_querycap(struct file *filp,
		void *priv, struct v4l2_capability *cap)
{
	struct stk_camera *dev = video_drvdata(filp);

	strcpy(cap->driver, "stk");
	strcpy(cap->card, "stk");
	usb_make_path(dev->udev, cap->bus_info, sizeof(cap->bus_info));

	cap->device_caps = V4L2_CAP_VIDEO_CAPTURE
		| V4L2_CAP_READWRITE | V4L2_CAP_STREAMING;
	cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
	return 0;
}

static int stk_vidioc_enum_input(struct file *filp,
		void *priv, struct v4l2_input *input)
{
	if (input->index != 0)
		return -EINVAL;

	strcpy(input->name, "Syntek USB Camera");
	input->type = V4L2_INPUT_TYPE_CAMERA;
	return 0;
}


static int stk_vidioc_g_input(struct file *filp, void *priv, unsigned int *i)
{
	*i = 0;
	return 0;
}

static int stk_vidioc_s_input(struct file *filp, void *priv, unsigned int i)
{
	return i ? -EINVAL : 0;
}

static int stk_s_ctrl(struct v4l2_ctrl *ctrl)
{
	struct stk_camera *dev =
		container_of(ctrl->handler, struct stk_camera, hdl);

	switch (ctrl->id) {
	case V4L2_CID_BRIGHTNESS:
		return stk_sensor_set_brightness(dev, ctrl->val);
	case V4L2_CID_HFLIP:
		if (dmi_check_system(stk_upside_down_dmi_table))
			dev->vsettings.hflip = !ctrl->val;
		else
			dev->vsettings.hflip = ctrl->val;
		return 0;
	case V4L2_CID_VFLIP:
		if (dmi_check_system(stk_upside_down_dmi_table))
			dev->vsettings.vflip = !ctrl->val;
		else
			dev->vsettings.vflip = ctrl->val;
		return 0;
	default:
		return -EINVAL;
	}
	return 0;
}


static int stk_vidioc_enum_fmt_vid_cap(struct file *filp,
		void *priv, struct v4l2_fmtdesc *fmtd)
{
	switch (fmtd->index) {
	case 0:
		fmtd->pixelformat = V4L2_PIX_FMT_RGB565;
		strcpy(fmtd->description, "r5g6b5");
		break;
	case 1:
		fmtd->pixelformat = V4L2_PIX_FMT_RGB565X;
		strcpy(fmtd->description, "r5g6b5BE");
		break;
	case 2:
		fmtd->pixelformat = V4L2_PIX_FMT_UYVY;
		strcpy(fmtd->description, "yuv4:2:2");
		break;
	case 3:
		fmtd->pixelformat = V4L2_PIX_FMT_SBGGR8;
		strcpy(fmtd->description, "Raw bayer");
		break;
	case 4:
		fmtd->pixelformat = V4L2_PIX_FMT_YUYV;
		strcpy(fmtd->description, "yuv4:2:2");
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

static struct stk_size {
	unsigned w;
	unsigned h;
	enum stk_mode m;
} stk_sizes[] = {
	{ .w = 1280, .h = 1024, .m = MODE_SXGA, },
	{ .w = 640,  .h = 480,  .m = MODE_VGA,  },
	{ .w = 352,  .h = 288,  .m = MODE_CIF,  },
	{ .w = 320,  .h = 240,  .m = MODE_QVGA, },
	{ .w = 176,  .h = 144,  .m = MODE_QCIF, },
};

static int stk_vidioc_g_fmt_vid_cap(struct file *filp,
		void *priv, struct v4l2_format *f)
{
	struct v4l2_pix_format *pix_format = &f->fmt.pix;
	struct stk_camera *dev = video_drvdata(filp);
	int i;

	for (i = 0; i < ARRAY_SIZE(stk_sizes) &&
			stk_sizes[i].m != dev->vsettings.mode; i++)
		;
	if (i == ARRAY_SIZE(stk_sizes)) {
		pr_err("ERROR: mode invalid\n");
		return -EINVAL;
	}
	pix_format->width = stk_sizes[i].w;
	pix_format->height = stk_sizes[i].h;
	pix_format->field = V4L2_FIELD_NONE;
	pix_format->colorspace = V4L2_COLORSPACE_SRGB;
	pix_format->pixelformat = dev->vsettings.palette;
	if (dev->vsettings.palette == V4L2_PIX_FMT_SBGGR8)
		pix_format->bytesperline = pix_format->width;
	else
		pix_format->bytesperline = 2 * pix_format->width;
	pix_format->sizeimage = pix_format->bytesperline
				* pix_format->height;
	return 0;
}

static int stk_try_fmt_vid_cap(struct file *filp,
		struct v4l2_format *fmtd, int *idx)
{
	int i;
	switch (fmtd->fmt.pix.pixelformat) {
	case V4L2_PIX_FMT_RGB565:
	case V4L2_PIX_FMT_RGB565X:
	case V4L2_PIX_FMT_UYVY:
	case V4L2_PIX_FMT_YUYV:
	case V4L2_PIX_FMT_SBGGR8:
		break;
	default:
		return -EINVAL;
	}
	for (i = 1; i < ARRAY_SIZE(stk_sizes); i++) {
		if (fmtd->fmt.pix.width > stk_sizes[i].w)
			break;
	}
	if (i == ARRAY_SIZE(stk_sizes)
		|| (abs(fmtd->fmt.pix.width - stk_sizes[i-1].w)
			< abs(fmtd->fmt.pix.width - stk_sizes[i].w))) {
		fmtd->fmt.pix.height = stk_sizes[i-1].h;
		fmtd->fmt.pix.width = stk_sizes[i-1].w;
		if (idx)
			*idx = i - 1;
	} else {
		fmtd->fmt.pix.height = stk_sizes[i].h;
		fmtd->fmt.pix.width = stk_sizes[i].w;
		if (idx)
			*idx = i;
	}

	fmtd->fmt.pix.field = V4L2_FIELD_NONE;
	fmtd->fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
	if (fmtd->fmt.pix.pixelformat == V4L2_PIX_FMT_SBGGR8)
		fmtd->fmt.pix.bytesperline = fmtd->fmt.pix.width;
	else
		fmtd->fmt.pix.bytesperline = 2 * fmtd->fmt.pix.width;
	fmtd->fmt.pix.sizeimage = fmtd->fmt.pix.bytesperline
		* fmtd->fmt.pix.height;
	return 0;
}

static int stk_vidioc_try_fmt_vid_cap(struct file *filp,
		void *priv, struct v4l2_format *fmtd)
{
	return stk_try_fmt_vid_cap(filp, fmtd, NULL);
}

static int stk_setup_format(struct stk_camera *dev)
{
	int i = 0;
	int depth;
	if (dev->vsettings.palette == V4L2_PIX_FMT_SBGGR8)
		depth = 1;
	else
		depth = 2;
	while (i < ARRAY_SIZE(stk_sizes) &&
			stk_sizes[i].m != dev->vsettings.mode)
		i++;
	if (i == ARRAY_SIZE(stk_sizes)) {
		pr_err("Something is broken in %s\n", __func__);
		return -EFAULT;
	}
	/* This registers controls some timings, not sure of what. */
	stk_camera_write_reg(dev, 0x001b, 0x0e);
	if (dev->vsettings.mode == MODE_SXGA)
		stk_camera_write_reg(dev, 0x001c, 0x0e);
	else
		stk_camera_write_reg(dev, 0x001c, 0x46);
	/*
	 * Registers 0x0115 0x0114 are the size of each line (bytes),
	 * regs 0x0117 0x0116 are the heigth of the image.
	 */
	stk_camera_write_reg(dev, 0x0115,
		((stk_sizes[i].w * depth) >> 8) & 0xff);
	stk_camera_write_reg(dev, 0x0114,
		(stk_sizes[i].w * depth) & 0xff);
	stk_camera_write_reg(dev, 0x0117,
		(stk_sizes[i].h >> 8) & 0xff);
	stk_camera_write_reg(dev, 0x0116,
		stk_sizes[i].h & 0xff);
	return stk_sensor_configure(dev);
}

static int stk_vidioc_s_fmt_vid_cap(struct file *filp,
		void *priv, struct v4l2_format *fmtd)
{
	int ret;
	int idx;
	struct stk_camera *dev = video_drvdata(filp);

	if (dev == NULL)
		return -ENODEV;
	if (!is_present(dev))
		return -ENODEV;
	if (is_streaming(dev))
		return -EBUSY;
	if (dev->owner)
		return -EBUSY;
	ret = stk_try_fmt_vid_cap(filp, fmtd, &idx);
	if (ret)
		return ret;

	dev->vsettings.palette = fmtd->fmt.pix.pixelformat;
	stk_free_buffers(dev);
	dev->frame_size = fmtd->fmt.pix.sizeimage;
	dev->vsettings.mode = stk_sizes[idx].m;

	stk_initialise(dev);
	return stk_setup_format(dev);
}

static int stk_vidioc_reqbufs(struct file *filp,
		void *priv, struct v4l2_requestbuffers *rb)
{
	struct stk_camera *dev = video_drvdata(filp);

	if (dev == NULL)
		return -ENODEV;
	if (rb->memory != V4L2_MEMORY_MMAP)
		return -EINVAL;
	if (is_streaming(dev)
		|| (dev->owner && dev->owner != filp))
		return -EBUSY;
	stk_free_buffers(dev);
	if (rb->count == 0) {
		stk_camera_write_reg(dev, 0x0, 0x49); /* turn off the LED */
		unset_initialised(dev);
		dev->owner = NULL;
		return 0;
	}
	dev->owner = filp;

	/*FIXME If they ask for zero, we must stop streaming and free */
	if (rb->count < 3)
		rb->count = 3;
	/* Arbitrary limit */
	else if (rb->count > 5)
		rb->count = 5;

	stk_allocate_buffers(dev, rb->count);
	rb->count = dev->n_sbufs;
	return 0;
}

static int stk_vidioc_querybuf(struct file *filp,
		void *priv, struct v4l2_buffer *buf)
{
	struct stk_camera *dev = video_drvdata(filp);
	struct stk_sio_buffer *sbuf;

	if (buf->index >= dev->n_sbufs)
		return -EINVAL;
	sbuf = dev->sio_bufs + buf->index;
	*buf = sbuf->v4lbuf;
	return 0;
}

static int stk_vidioc_qbuf(struct file *filp,
		void *priv, struct v4l2_buffer *buf)
{
	struct stk_camera *dev = video_drvdata(filp);
	struct stk_sio_buffer *sbuf;
	unsigned long flags;

	if (buf->memory != V4L2_MEMORY_MMAP)
		return -EINVAL;

	if (buf->index >= dev->n_sbufs)
		return -EINVAL;
	sbuf = dev->sio_bufs + buf->index;
	if (sbuf->v4lbuf.flags & V4L2_BUF_FLAG_QUEUED)
		return 0;
	sbuf->v4lbuf.flags |= V4L2_BUF_FLAG_QUEUED;
	sbuf->v4lbuf.flags &= ~V4L2_BUF_FLAG_DONE;
	spin_lock_irqsave(&dev->spinlock, flags);
	list_add_tail(&sbuf->list, &dev->sio_avail);
	*buf = sbuf->v4lbuf;
	spin_unlock_irqrestore(&dev->spinlock, flags);
	return 0;
}

static int stk_vidioc_dqbuf(struct file *filp,
		void *priv, struct v4l2_buffer *buf)
{
	struct stk_camera *dev = video_drvdata(filp);
	struct stk_sio_buffer *sbuf;
	unsigned long flags;
	int ret;

	if (!is_streaming(dev))
		return -EINVAL;

	if (filp->f_flags & O_NONBLOCK && list_empty(&dev->sio_full))
		return -EWOULDBLOCK;
	ret = wait_event_interruptible(dev->wait_frame,
		!list_empty(&dev->sio_full) || !is_present(dev));
	if (ret)
		return ret;
	if (!is_present(dev))
		return -EIO;

	spin_lock_irqsave(&dev->spinlock, flags);
	sbuf = list_first_entry(&dev->sio_full, struct stk_sio_buffer, list);
	list_del_init(&sbuf->list);
	spin_unlock_irqrestore(&dev->spinlock, flags);
	sbuf->v4lbuf.flags &= ~V4L2_BUF_FLAG_QUEUED;
	sbuf->v4lbuf.flags |= V4L2_BUF_FLAG_DONE;
	sbuf->v4lbuf.sequence = ++dev->sequence;
	v4l2_get_timestamp(&sbuf->v4lbuf.timestamp);

	*buf = sbuf->v4lbuf;
	return 0;
}

static int stk_vidioc_streamon(struct file *filp,
		void *priv, enum v4l2_buf_type type)
{
	struct stk_camera *dev = video_drvdata(filp);
	if (is_streaming(dev))
		return 0;
	if (dev->sio_bufs == NULL)
		return -EINVAL;
	dev->sequence = 0;
	return stk_start_stream(dev);
}

static int stk_vidioc_streamoff(struct file *filp,
		void *priv, enum v4l2_buf_type type)
{
	struct stk_camera *dev = video_drvdata(filp);
	unsigned long flags;
	int i;
	stk_stop_stream(dev);
	spin_lock_irqsave(&dev->spinlock, flags);
	INIT_LIST_HEAD(&dev->sio_avail);
	INIT_LIST_HEAD(&dev->sio_full);
	for (i = 0; i < dev->n_sbufs; i++) {
		INIT_LIST_HEAD(&dev->sio_bufs[i].list);
		dev->sio_bufs[i].v4lbuf.flags = 0;
	}
	spin_unlock_irqrestore(&dev->spinlock, flags);
	return 0;
}


static int stk_vidioc_g_parm(struct file *filp,
		void *priv, struct v4l2_streamparm *sp)
{
	/*FIXME This is not correct */
	sp->parm.capture.timeperframe.numerator = 1;
	sp->parm.capture.timeperframe.denominator = 30;
	sp->parm.capture.readbuffers = 2;
	return 0;
}

static int stk_vidioc_enum_framesizes(struct file *filp,
		void *priv, struct v4l2_frmsizeenum *frms)
{
	if (frms->index >= ARRAY_SIZE(stk_sizes))
		return -EINVAL;
	switch (frms->pixel_format) {
	case V4L2_PIX_FMT_RGB565:
	case V4L2_PIX_FMT_RGB565X:
	case V4L2_PIX_FMT_UYVY:
	case V4L2_PIX_FMT_YUYV:
	case V4L2_PIX_FMT_SBGGR8:
		frms->type = V4L2_FRMSIZE_TYPE_DISCRETE;
		frms->discrete.width = stk_sizes[frms->index].w;
		frms->discrete.height = stk_sizes[frms->index].h;
		return 0;
	default: return -EINVAL;
	}
}

static const struct v4l2_ctrl_ops stk_ctrl_ops = {
	.s_ctrl = stk_s_ctrl,
};

static const struct v4l2_file_operations v4l_stk_fops = {
	.owner = THIS_MODULE,
	.open = v4l_stk_open,
	.release = v4l_stk_release,
	.read = v4l_stk_read,
	.poll = v4l_stk_poll,
	.mmap = v4l_stk_mmap,
	.unlocked_ioctl = video_ioctl2,
};

static const struct v4l2_ioctl_ops v4l_stk_ioctl_ops = {
	.vidioc_querycap = stk_vidioc_querycap,
	.vidioc_enum_fmt_vid_cap = stk_vidioc_enum_fmt_vid_cap,
	.vidioc_try_fmt_vid_cap = stk_vidioc_try_fmt_vid_cap,
	.vidioc_s_fmt_vid_cap = stk_vidioc_s_fmt_vid_cap,
	.vidioc_g_fmt_vid_cap = stk_vidioc_g_fmt_vid_cap,
	.vidioc_enum_input = stk_vidioc_enum_input,
	.vidioc_s_input = stk_vidioc_s_input,
	.vidioc_g_input = stk_vidioc_g_input,
	.vidioc_reqbufs = stk_vidioc_reqbufs,
	.vidioc_querybuf = stk_vidioc_querybuf,
	.vidioc_qbuf = stk_vidioc_qbuf,
	.vidioc_dqbuf = stk_vidioc_dqbuf,
	.vidioc_streamon = stk_vidioc_streamon,
	.vidioc_streamoff = stk_vidioc_streamoff,
	.vidioc_g_parm = stk_vidioc_g_parm,
	.vidioc_enum_framesizes = stk_vidioc_enum_framesizes,
	.vidioc_log_status = v4l2_ctrl_log_status,
	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
};

static void stk_v4l_dev_release(struct video_device *vd)
{
	struct stk_camera *dev = vdev_to_camera(vd);

	if (dev->sio_bufs != NULL || dev->isobufs != NULL)
		pr_err("We are leaking memory\n");
	usb_put_intf(dev->interface);
}

static const struct video_device stk_v4l_data = {
	.name = "stkwebcam",
	.fops = &v4l_stk_fops,
	.ioctl_ops = &v4l_stk_ioctl_ops,
	.release = stk_v4l_dev_release,
};


static int stk_register_video_device(struct stk_camera *dev)
{
	int err;

	dev->vdev = stk_v4l_data;
	dev->vdev.lock = &dev->lock;
	dev->vdev.v4l2_dev = &dev->v4l2_dev;
	video_set_drvdata(&dev->vdev, dev);
	err = video_register_device(&dev->vdev, VFL_TYPE_GRABBER, -1);
	if (err)
		pr_err("v4l registration failed\n");
	else
		pr_info("Syntek USB2.0 Camera is now controlling device %s\n",
			video_device_node_name(&dev->vdev));
	return err;
}


/* USB Stuff */

static int stk_camera_probe(struct usb_interface *interface,
		const struct usb_device_id *id)
{
	struct v4l2_ctrl_handler *hdl;
	int err = 0;
	int i;

	struct stk_camera *dev = NULL;
	struct usb_device *udev = interface_to_usbdev(interface);
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;

	dev = kzalloc(sizeof(struct stk_camera), GFP_KERNEL);
	if (dev == NULL) {
		pr_err("Out of memory !\n");
		return -ENOMEM;
	}
	err = v4l2_device_register(&interface->dev, &dev->v4l2_dev);
	if (err < 0) {
		dev_err(&udev->dev, "couldn't register v4l2_device\n");
		kfree(dev);
		return err;
	}
	hdl = &dev->hdl;
	v4l2_ctrl_handler_init(hdl, 3);
	v4l2_ctrl_new_std(hdl, &stk_ctrl_ops,
			  V4L2_CID_BRIGHTNESS, 0, 0xff, 0x1, 0x60);
	v4l2_ctrl_new_std(hdl, &stk_ctrl_ops,
			  V4L2_CID_HFLIP, 0, 1, 1, 1);
	v4l2_ctrl_new_std(hdl, &stk_ctrl_ops,
			  V4L2_CID_VFLIP, 0, 1, 1, 1);
	if (hdl->error) {
		err = hdl->error;
		dev_err(&udev->dev, "couldn't register control\n");
		goto error;
	}
	dev->v4l2_dev.ctrl_handler = hdl;

	spin_lock_init(&dev->spinlock);
	mutex_init(&dev->lock);
	init_waitqueue_head(&dev->wait_frame);
	dev->first_init = 1; /* webcam LED management */

	dev->udev = udev;
	dev->interface = interface;
	usb_get_intf(interface);

	if (hflip != -1)
		dev->vsettings.hflip = hflip;
	else if (dmi_check_system(stk_upside_down_dmi_table))
		dev->vsettings.hflip = 1;
	else
		dev->vsettings.hflip = 0;
	if (vflip != -1)
		dev->vsettings.vflip = vflip;
	else if (dmi_check_system(stk_upside_down_dmi_table))
		dev->vsettings.vflip = 1;
	else
		dev->vsettings.vflip = 0;
	dev->n_sbufs = 0;
	set_present(dev);

	/* Set up the endpoint information
	 * use only the first isoc-in endpoint
	 * for the current alternate setting */
	iface_desc = interface->cur_altsetting;

	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
		endpoint = &iface_desc->endpoint[i].desc;

		if (!dev->isoc_ep
			&& usb_endpoint_is_isoc_in(endpoint)) {
			/* we found an isoc in endpoint */
			dev->isoc_ep = usb_endpoint_num(endpoint);
			break;
		}
	}
	if (!dev->isoc_ep) {
		pr_err("Could not find isoc-in endpoint\n");
		err = -ENODEV;
		goto error;
	}
	dev->vsettings.palette = V4L2_PIX_FMT_RGB565;
	dev->vsettings.mode = MODE_VGA;
	dev->frame_size = 640 * 480 * 2;

	INIT_LIST_HEAD(&dev->sio_avail);
	INIT_LIST_HEAD(&dev->sio_full);

	usb_set_intfdata(interface, dev);

	err = stk_register_video_device(dev);
	if (err)
		goto error;

	return 0;

error:
	v4l2_ctrl_handler_free(hdl);
	v4l2_device_unregister(&dev->v4l2_dev);
	kfree(dev);
	return err;
}

static void stk_camera_disconnect(struct usb_interface *interface)
{
	struct stk_camera *dev = usb_get_intfdata(interface);

	usb_set_intfdata(interface, NULL);
	unset_present(dev);

	wake_up_interruptible(&dev->wait_frame);

	pr_info("Syntek USB2.0 Camera release resources device %s\n",
		video_device_node_name(&dev->vdev));

	video_unregister_device(&dev->vdev);
	v4l2_ctrl_handler_free(&dev->hdl);
	v4l2_device_unregister(&dev->v4l2_dev);
	kfree(dev);
}

#ifdef CONFIG_PM
static int stk_camera_suspend(struct usb_interface *intf, pm_message_t message)
{
	struct stk_camera *dev = usb_get_intfdata(intf);
	if (is_streaming(dev)) {
		stk_stop_stream(dev);
		/* yes, this is ugly */
		set_streaming(dev);
	}
	return 0;
}

static int stk_camera_resume(struct usb_interface *intf)
{
	struct stk_camera *dev = usb_get_intfdata(intf);
	if (!is_initialised(dev))
		return 0;
	unset_initialised(dev);
	stk_initialise(dev);
	stk_camera_write_reg(dev, 0x0, 0x49);
	stk_setup_format(dev);
	if (is_streaming(dev))
		stk_start_stream(dev);
	return 0;
}
#endif

static struct usb_driver stk_camera_driver = {
	.name = "stkwebcam",
	.probe = stk_camera_probe,
	.disconnect = stk_camera_disconnect,
	.id_table = stkwebcam_table,
#ifdef CONFIG_PM
	.suspend = stk_camera_suspend,
	.resume = stk_camera_resume,
#endif
};

module_usb_driver(stk_camera_driver);