/*
 * Video capture interface for Linux version 2
 *
 *      A generic video device interface for the LINUX operating system
 *      using a set of device structures/vectors for low level operations.
 *
 *      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.
 *
 * Authors:     Alan Cox, <alan@lxorguk.ukuu.org.uk> (version 1)
 *              Mauro Carvalho Chehab <mchehab@infradead.org> (version 2)
 *
 * Fixes:       20000516  Claudio Matsuoka <claudio@conectiva.com>
 *              - Added procfs support
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/system.h>

#include <media/v4l2-common.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>

#define VIDEO_NUM_DEVICES       256
#define VIDEO_NAME              "video4linux"

/*
 *      sysfs stuff
 */

static ssize_t show_index(struct device *cd,
                         struct device_attribute *attr, char *buf)
{
        struct video_device *vdev = to_video_device(cd);

        return sprintf(buf, "%i\n", vdev->index);
}

static ssize_t show_name(struct device *cd,
                         struct device_attribute *attr, char *buf)
{
        struct video_device *vdev = to_video_device(cd);

        return sprintf(buf, "%.*s\n", (int)sizeof(vdev->name), vdev->name);
}

static struct device_attribute video_device_attrs[] = {
        __ATTR(name, S_IRUGO, show_name, NULL),
        __ATTR(index, S_IRUGO, show_index, NULL),
        __ATTR_NULL
};

/*
 *      Active devices
 */
static struct video_device *video_device[VIDEO_NUM_DEVICES];
static DEFINE_MUTEX(videodev_lock);
static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);

/* Device node utility functions */

/* Note: these utility functions all assume that vfl_type is in the range
   [0, VFL_TYPE_MAX-1]. */

#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
/* Return the bitmap corresponding to vfl_type. */
static inline unsigned long *devnode_bits(int vfl_type)
{
        /* Any types not assigned to fixed minor ranges must be mapped to
           one single bitmap for the purposes of finding a free node number
           since all those unassigned types use the same minor range. */
        int idx = (vfl_type > VFL_TYPE_RADIO) ? VFL_TYPE_MAX - 1 : vfl_type;

        return devnode_nums[idx];
}
#else
/* Return the bitmap corresponding to vfl_type. */
static inline unsigned long *devnode_bits(int vfl_type)
{
        return devnode_nums[vfl_type];
}
#endif

/* Mark device node number vdev->num as used */
static inline void devnode_set(struct video_device *vdev)
{
        set_bit(vdev->num, devnode_bits(vdev->vfl_type));
}

/* Mark device node number vdev->num as unused */
static inline void devnode_clear(struct video_device *vdev)
{
        clear_bit(vdev->num, devnode_bits(vdev->vfl_type));
}

/* Try to find a free device node number in the range [from, to> */
static inline int devnode_find(struct video_device *vdev, int from, int to)
{
        return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);
}

struct video_device *video_device_alloc(void)
{
        return kzalloc(sizeof(struct video_device), GFP_KERNEL);
}
EXPORT_SYMBOL(video_device_alloc);

void video_device_release(struct video_device *vdev)
{
        kfree(vdev);
}
EXPORT_SYMBOL(video_device_release);

void video_device_release_empty(struct video_device *vdev)
{
        /* Do nothing */
        /* Only valid when the video_device struct is a static. */
}
EXPORT_SYMBOL(video_device_release_empty);

static inline void video_get(struct video_device *vdev)
{
        get_device(&vdev->dev);
}

static inline void video_put(struct video_device *vdev)
{
        put_device(&vdev->dev);
}

/* Called when the last user of the video device exits. */
static void v4l2_device_release(struct device *cd)
{
        struct video_device *vdev = to_video_device(cd);

        mutex_lock(&videodev_lock);
        if (video_device[vdev->minor] != vdev) {
                mutex_unlock(&videodev_lock);
                /* should not happen */
                WARN_ON(1);
                return;
        }

        /* Free up this device for reuse */
        video_device[vdev->minor] = NULL;

        /* Delete the cdev on this minor as well */
        cdev_del(vdev->cdev);
        /* Just in case some driver tries to access this from
           the release() callback. */
        vdev->cdev = NULL;

        /* Mark device node number as free */
        devnode_clear(vdev);

        mutex_unlock(&videodev_lock);

        /* Release video_device and perform other
           cleanups as needed. */
        vdev->release(vdev);
}

static struct class video_class = {
        .name = VIDEO_NAME,
        .dev_attrs = video_device_attrs,
};

struct video_device *video_devdata(struct file *file)
{
        return video_device[iminor(file->f_path.dentry->d_inode)];
}
EXPORT_SYMBOL(video_devdata);

static ssize_t v4l2_read(struct file *filp, char __user *buf,
                size_t sz, loff_t *off)
{
        struct video_device *vdev = video_devdata(filp);
        int ret = -ENODEV;

        if (!vdev->fops->read)
                return -EINVAL;
        if (vdev->lock && mutex_lock_interruptible(vdev->lock))
                return -ERESTARTSYS;
        if (video_is_registered(vdev))
                ret = vdev->fops->read(filp, buf, sz, off);
        if (vdev->lock)
                mutex_unlock(vdev->lock);
        return ret;
}

static ssize_t v4l2_write(struct file *filp, const char __user *buf,
                size_t sz, loff_t *off)
{
        struct video_device *vdev = video_devdata(filp);
        int ret = -ENODEV;

        if (!vdev->fops->write)
                return -EINVAL;
        if (vdev->lock && mutex_lock_interruptible(vdev->lock))
                return -ERESTARTSYS;
        if (video_is_registered(vdev))
                ret = vdev->fops->write(filp, buf, sz, off);
        if (vdev->lock)
                mutex_unlock(vdev->lock);
        return ret;
}

static unsigned int v4l2_poll(struct file *filp, struct poll_table_struct *poll)
{
        struct video_device *vdev = video_devdata(filp);
        int ret = POLLERR | POLLHUP;

        if (!vdev->fops->poll)
                return DEFAULT_POLLMASK;
        if (vdev->lock)
                mutex_lock(vdev->lock);
        if (video_is_registered(vdev))
                ret = vdev->fops->poll(filp, poll);
        if (vdev->lock)
                mutex_unlock(vdev->lock);
        return ret;
}

static long v4l2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct video_device *vdev = video_devdata(filp);
        int ret = -ENODEV;

        if (vdev->fops->unlocked_ioctl) {
                if (vdev->lock && mutex_lock_interruptible(vdev->lock))
                        return -ERESTARTSYS;
                if (video_is_registered(vdev))
                        ret = vdev->fops->unlocked_ioctl(filp, cmd, arg);
                if (vdev->lock)
                        mutex_unlock(vdev->lock);
        } else if (vdev->fops->ioctl) {
                /* This code path is a replacement for the BKL. It is a major
                 * hack but it will have to do for those drivers that are not
                 * yet converted to use unlocked_ioctl.
                 *
                 * There are two options: if the driver implements struct
                 * v4l2_device, then the lock defined there is used to
                 * serialize the ioctls. Otherwise the v4l2 core lock defined
                 * below is used. This lock is really bad since it serializes
                 * completely independent devices.
                 *
                 * Both variants suffer from the same problem: if the driver
                 * sleeps, then it blocks all ioctls since the lock is still
                 * held. This is very common for VIDIOC_DQBUF since that
                 * normally waits for a frame to arrive. As a result any other
                 * ioctl calls will proceed very, very slowly since each call
                 * will have to wait for the VIDIOC_QBUF to finish. Things that
                 * should take 0.01s may now take 10-20 seconds.
                 *
                 * The workaround is to *not* take the lock for VIDIOC_DQBUF.
                 * This actually works OK for videobuf-based drivers, since
                 * videobuf will take its own internal lock.
                 */
                static DEFINE_MUTEX(v4l2_ioctl_mutex);
                struct mutex *m = vdev->v4l2_dev ?
                        &vdev->v4l2_dev->ioctl_lock : &v4l2_ioctl_mutex;

                if (cmd != VIDIOC_DQBUF && mutex_lock_interruptible(m))
                        return -ERESTARTSYS;
                if (video_is_registered(vdev))
                        ret = vdev->fops->ioctl(filp, cmd, arg);
                if (cmd != VIDIOC_DQBUF)
                        mutex_unlock(m);
        } else
                ret = -ENOTTY;

        return ret;
}

static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
{
        struct video_device *vdev = video_devdata(filp);
        int ret = -ENODEV;

        if (!vdev->fops->mmap)
                return ret;
        if (vdev->lock && mutex_lock_interruptible(vdev->lock))
                return -ERESTARTSYS;
        if (video_is_registered(vdev))
                ret = vdev->fops->mmap(filp, vm);
        if (vdev->lock)
                mutex_unlock(vdev->lock);
        return ret;
}

/* Override for the open function */
static int v4l2_open(struct inode *inode, struct file *filp)
{
        struct video_device *vdev;
        int ret = 0;

        /* Check if the video device is available */
        mutex_lock(&videodev_lock);
        vdev = video_devdata(filp);
        /* return ENODEV if the video device has already been removed. */
        if (vdev == NULL || !video_is_registered(vdev)) {
                mutex_unlock(&videodev_lock);
                return -ENODEV;
        }
        /* and increase the device refcount */
        video_get(vdev);
        mutex_unlock(&videodev_lock);
        if (vdev->fops->open) {
                if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
                        ret = -ERESTARTSYS;
                        goto err;
                }
                if (video_is_registered(vdev))
                        ret = vdev->fops->open(filp);
                else
                        ret = -ENODEV;
                if (vdev->lock)
                        mutex_unlock(vdev->lock);
        }

err:
        /* decrease the refcount in case of an error */
        if (ret)
                video_put(vdev);
        return ret;
}

/* Override for the release function */
static int v4l2_release(struct inode *inode, struct file *filp)
{
        struct video_device *vdev = video_devdata(filp);
        int ret = 0;

        if (vdev->fops->release) {
                if (vdev->lock)
                        mutex_lock(vdev->lock);
                vdev->fops->release(filp);
                if (vdev->lock)
                        mutex_unlock(vdev->lock);
        }

        /* decrease the refcount unconditionally since the release()
           return value is ignored. */
        video_put(vdev);
        return ret;
}

static const struct file_operations v4l2_fops = {
        .owner = THIS_MODULE,
        .read = v4l2_read,
        .write = v4l2_write,
        .open = v4l2_open,
        .mmap = v4l2_mmap,
        .unlocked_ioctl = v4l2_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl = v4l2_compat_ioctl32,
#endif
        .release = v4l2_release,
        .poll = v4l2_poll,
        .llseek = no_llseek,
};

/**
 * get_index - assign stream index number based on parent device
 * @vdev: video_device to assign index number to, vdev->parent should be assigned
 *
 * Note that when this is called the new device has not yet been registered
 * in the video_device array, but it was able to obtain a minor number.
 *
 * This means that we can always obtain a free stream index number since
 * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
 * use of the video_device array.
 *
 * Returns a free index number.
 */
static int get_index(struct video_device *vdev)
{
        /* This can be static since this function is called with the global
           videodev_lock held. */
        static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
        int i;

        /* Some drivers do not set the parent. In that case always return 0. */
        if (vdev->parent == NULL)
                return 0;

        bitmap_zero(used, VIDEO_NUM_DEVICES);

        for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
                if (video_device[i] != NULL &&
                    video_device[i]->parent == vdev->parent) {
                        set_bit(video_device[i]->index, used);
                }
        }

        return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
}

/**
 *      video_register_device - register video4linux devices
 *      @vdev: video device structure we want to register
 *      @type: type of device to register
 *      @nr:   which device node number (0 == /dev/video0, 1 == /dev/video1, ...
 *             -1 == first free)
 *      @warn_if_nr_in_use: warn if the desired device node number
 *             was already in use and another number was chosen instead.
 *
 *      The registration code assigns minor numbers and device node numbers
 *      based on the requested type and registers the new device node with
 *      the kernel.
 *
 *      This function assumes that struct video_device was zeroed when it
 *      was allocated and does not contain any stale date.
 *
 *      An error is returned if no free minor or device node number could be
 *      found, or if the registration of the device node failed.
 *
 *      Zero is returned on success.
 *
 *      Valid types are
 *
 *      %VFL_TYPE_GRABBER - A frame grabber
 *
 *      %VFL_TYPE_VBI - Vertical blank data (undecoded)
 *
 *      %VFL_TYPE_RADIO - A radio card
 */
static int __video_register_device(struct video_device *vdev, int type, int nr,
                int warn_if_nr_in_use)
{
        int i = 0;
        int ret;
        int minor_offset = 0;
        int minor_cnt = VIDEO_NUM_DEVICES;
        const char *name_base;

        /* A minor value of -1 marks this video device as never
           having been registered */
        vdev->minor = -1;

        /* the release callback MUST be present */
        WARN_ON(!vdev->release);
        if (!vdev->release)
                return -EINVAL;

        /* v4l2_fh support */
        spin_lock_init(&vdev->fh_lock);
        INIT_LIST_HEAD(&vdev->fh_list);

        /* Part 1: check device type */
        switch (type) {
        case VFL_TYPE_GRABBER:
                name_base = "video";
                break;
        case VFL_TYPE_VBI:
                name_base = "vbi";
                break;
        case VFL_TYPE_RADIO:
                name_base = "radio";
                break;
        default:
                printk(KERN_ERR "%s called with unknown type: %d\n",
                       __func__, type);
                return -EINVAL;
        }

        vdev->vfl_type = type;
        vdev->cdev = NULL;
        if (vdev->v4l2_dev) {
                if (vdev->v4l2_dev->dev)
                        vdev->parent = vdev->v4l2_dev->dev;
                if (vdev->ctrl_handler == NULL)
                        vdev->ctrl_handler = vdev->v4l2_dev->ctrl_handler;
        }

        /* Part 2: find a free minor, device node number and device index. */
#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
        /* Keep the ranges for the first four types for historical
         * reasons.
         * Newer devices (not yet in place) should use the range
         * of 128-191 and just pick the first free minor there
         * (new style). */
        switch (type) {
        case VFL_TYPE_GRABBER:
                minor_offset = 0;
                minor_cnt = 64;
                break;
        case VFL_TYPE_RADIO:
                minor_offset = 64;
                minor_cnt = 64;
                break;
        case VFL_TYPE_VBI:
                minor_offset = 224;
                minor_cnt = 32;
                break;
        default:
                minor_offset = 128;
                minor_cnt = 64;
                break;
        }
#endif

        /* Pick a device node number */
        mutex_lock(&videodev_lock);
        nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
        if (nr == minor_cnt)
                nr = devnode_find(vdev, 0, minor_cnt);
        if (nr == minor_cnt) {
                printk(KERN_ERR "could not get a free device node number\n");
                mutex_unlock(&videodev_lock);
                return -ENFILE;
        }
#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
        /* 1-on-1 mapping of device node number to minor number */
        i = nr;
#else
        /* The device node number and minor numbers are independent, so
           we just find the first free minor number. */
        for (i = 0; i < VIDEO_NUM_DEVICES; i++)
                if (video_device[i] == NULL)
                        break;
        if (i == VIDEO_NUM_DEVICES) {
                mutex_unlock(&videodev_lock);
                printk(KERN_ERR "could not get a free minor\n");
                return -ENFILE;
        }
#endif
        vdev->minor = i + minor_offset;
        vdev->num = nr;
        devnode_set(vdev);

        /* Should not happen since we thought this minor was free */
        WARN_ON(video_device[vdev->minor] != NULL);
        vdev->index = get_index(vdev);
        mutex_unlock(&videodev_lock);

        /* Part 3: Initialize the character device */
        vdev->cdev = cdev_alloc();
        if (vdev->cdev == NULL) {
                ret = -ENOMEM;
                goto cleanup;
        }
        vdev->cdev->ops = &v4l2_fops;
        vdev->cdev->owner = vdev->fops->owner;
        ret = cdev_add(vdev->cdev, MKDEV(VIDEO_MAJOR, vdev->minor), 1);
        if (ret < 0) {
                printk(KERN_ERR "%s: cdev_add failed\n", __func__);
                kfree(vdev->cdev);
                vdev->cdev = NULL;
                goto cleanup;
        }

        /* Part 4: register the device with sysfs */
        vdev->dev.class = &video_class;
        vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
        if (vdev->parent)
                vdev->dev.parent = vdev->parent;
        dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
        ret = device_register(&vdev->dev);
        if (ret < 0) {
                printk(KERN_ERR "%s: device_register failed\n", __func__);
                goto cleanup;
        }
        /* Register the release callback that will be called when the last
           reference to the device goes away. */
        vdev->dev.release = v4l2_device_release;

        if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
                printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
                        name_base, nr, video_device_node_name(vdev));

        /* Part 5: Activate this minor. The char device can now be used. */
        set_bit(V4L2_FL_REGISTERED, &vdev->flags);
        mutex_lock(&videodev_lock);
        video_device[vdev->minor] = vdev;
        mutex_unlock(&videodev_lock);
        return 0;

cleanup:
        mutex_lock(&videodev_lock);
        if (vdev->cdev)
                cdev_del(vdev->cdev);
        devnode_clear(vdev);
        mutex_unlock(&videodev_lock);
        /* Mark this video device as never having been registered. */
        vdev->minor = -1;
        return ret;
}

int video_register_device(struct video_device *vdev, int type, int nr)
{
        return __video_register_device(vdev, type, nr, 1);
}
EXPORT_SYMBOL(video_register_device);

int video_register_device_no_warn(struct video_device *vdev, int type, int nr)
{
        return __video_register_device(vdev, type, nr, 0);
}
EXPORT_SYMBOL(video_register_device_no_warn);

/**
 *      video_unregister_device - unregister a video4linux device
 *      @vdev: the device to unregister
 *
 *      This unregisters the passed device. Future open calls will
 *      be met with errors.
 */
void video_unregister_device(struct video_device *vdev)
{
        /* Check if vdev was ever registered at all */
        if (!vdev || !video_is_registered(vdev))
                return;

        mutex_lock(&videodev_lock);
        /* This must be in a critical section to prevent a race with v4l2_open.
         * Once this bit has been cleared video_get may never be called again.
         */
        clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
        mutex_unlock(&videodev_lock);
        device_unregister(&vdev->dev);
}
EXPORT_SYMBOL(video_unregister_device);

/*
 *      Initialise video for linux
 */
static int __init videodev_init(void)
{
        dev_t dev = MKDEV(VIDEO_MAJOR, 0);
        int ret;

        printk(KERN_INFO "Linux video capture interface: v2.00\n");
        ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
        if (ret < 0) {
                printk(KERN_WARNING "videodev: unable to get major %d\n",
                                VIDEO_MAJOR);
                return ret;
        }

        ret = class_register(&video_class);
        if (ret < 0) {
                unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
                printk(KERN_WARNING "video_dev: class_register failed\n");
                return -EIO;
        }

        return 0;
}

static void __exit videodev_exit(void)
{
        dev_t dev = MKDEV(VIDEO_MAJOR, 0);

        class_unregister(&video_class);
        unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
}

module_init(videodev_init)
module_exit(videodev_exit)

MODULE_AUTHOR("Alan Cox, Mauro Carvalho Chehab <mchehab@infradead.org>");
MODULE_DESCRIPTION("Device registrar for Video4Linux drivers v2");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(VIDEO_MAJOR);


/*
 * Local variables:
 * c-basic-offset: 8
 * End:
 */