path: root/drivers/media/v4l2-core/v4l2-dev.c

/*
 * 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 <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_debug(struct device *cd,
			 struct device_attribute *attr, char *buf)
{
	struct video_device *vdev = to_video_device(cd);

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

static ssize_t set_debug(struct device *cd, struct device_attribute *attr,
		   const char *buf, size_t len)
{
	struct video_device *vdev = to_video_device(cd);
	int res = 0;
	u16 value;

	res = kstrtou16(buf, 0, &value);
	if (res)
		return res;

	vdev->debug = value;
	return len;
}

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(debug, 0644, show_debug, set_debug),
	__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)
{