videodev.c

linux-2.4.29操作系统的源码

/*
 * Video capture interface for Linux
 *
 *		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.
 *
 * Author:	Alan Cox, <[e-mail]>
 *
 * Fixes:	20000516  Claudio Matsuoka <[e-mail]>
 *		- Added procfs support
 */

#include <linux/config.h>
#include <linux/version.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp_lock.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 <asm/semaphore.h>

#include <linux/videodev.h>

#define VIDEO_NUM_DEVICES	256 

/*
 *	Active devices 
 */
 
static struct video_device *video_device[VIDEO_NUM_DEVICES];
static DECLARE_MUTEX(videodev_lock);


#if defined(CONFIG_PROC_FS) && defined(CONFIG_VIDEO_PROC_FS)

#include <linux/proc_fs.h>

struct videodev_proc_data {
	struct list_head proc_list;
	char name[16];
	struct video_device *vdev;
	struct proc_dir_entry *proc_entry;
};

static struct proc_dir_entry *video_dev_proc_entry = NULL;
struct proc_dir_entry *video_proc_entry = NULL;
EXPORT_SYMBOL(video_proc_entry);
LIST_HEAD(videodev_proc_list);

#endif /* CONFIG_PROC_FS && CONFIG_VIDEO_PROC_FS */

struct video_device *video_device_alloc(void)
{
	struct video_device *vfd;
	vfd = kmalloc(sizeof(*vfd),GFP_KERNEL);
	if (NULL == vfd)
		return NULL;
	memset(vfd,0,sizeof(*vfd));
	return vfd;
}

void video_device_release(struct video_device *vfd)
{
	kfree(vfd);
}

/*
 *	Read will do some smarts later on. Buffer pin etc.
 */
 
static ssize_t video_read(struct file *file,
	char *buf, size_t count, loff_t *ppos)
{
	struct video_device *vfl = video_devdata(file);
	if(vfl->read)
		return vfl->read(vfl, buf, count, file->f_flags&O_NONBLOCK);
	else
		return -EINVAL;
}


/*
 *	Write for now does nothing. No reason it shouldnt do overlay setting
 *	for some boards I guess..
 */

static ssize_t video_write(struct file *file, const char *buf, 
	size_t count, loff_t *ppos)
{
	struct video_device *vfl = video_devdata(file);
	if(vfl->write)
		return vfl->write(vfl, buf, count, file->f_flags&O_NONBLOCK);
	else
		return 0;
}

struct video_device* video_devdata(struct file *file)
{
	return video_device[minor(file->f_dentry->d_inode->i_rdev)];
}

/*
 *	Poll to see if we're readable, can probably be used for timing on incoming
 *	frames, etc..
 */

static unsigned int video_poll(struct file *file, poll_table * wait)
{
	struct video_device *vfl = video_devdata(file);
	if(vfl->poll)
		return vfl->poll(vfl, file, wait);
	else
		return 0;
}


/*
 *	Open a video device.
 */

static int video_open(struct inode *inode, struct file *file)
{
	unsigned int minor = minor(inode->i_rdev);
	int err = 0;
	struct video_device *vfl;
	
	if(minor>=VIDEO_NUM_DEVICES)
		return -ENODEV;
	down(&videodev_lock);
	vfl=video_device[minor];
	if(vfl==NULL) {
		char modname[20];

		up(&videodev_lock);
		sprintf (modname, "char-major-%d-%d", VIDEO_MAJOR, minor);
		request_module(modname);
		down(&videodev_lock);
		vfl=video_device[minor];
		if (vfl==NULL) {
			err = -ENODEV;
			goto unlock_out;
		}
	}
	if (vfl->fops) {
		struct file_operations *old_fops;

		old_fops = file->f_op;
                file->f_op = fops_get(vfl->fops);
                if(file->f_op->open)
                        err = file->f_op->open(inode,file);
                if (err) {
                        fops_put(file->f_op);
                        file->f_op = fops_get(old_fops);
                }
                fops_put(old_fops);
		goto unlock_out;
	}
	if(vfl->users) {
		err = -EBUSY;
		goto unlock_out;
	}
	vfl->users++;		/* In case vfl->open sleeps */
	
	if(vfl->owner)
		__MOD_INC_USE_COUNT(vfl->owner);
	
	if (vfl->open) {
		err=vfl->open(vfl,0);	/* Tell the device it is open */
		if (err) {
			vfl->users--;
			if(vfl->owner)
				__MOD_DEC_USE_COUNT(vfl->owner);
			goto unlock_out;
		}
	}
	err = 0;
	
unlock_out:
	up(&videodev_lock);
	return err;
}

/*
 *	Last close of a video for Linux device
 */
	
static int video_release(struct inode *inode, struct file *file)
{
	struct video_device *vfl;
	struct module *owner;

	vfl = video_devdata(file);
	owner = vfl->owner;
	if (vfl->close)
		vfl->close(vfl);

	down(&videodev_lock);
	/* ->close() might have called video_device_unregister()
           in case of a hot unplug, thus we have to get vfl again */
	vfl = video_devdata(file);
	if (NULL != vfl)
		vfl->users--;
	if (owner)
		__MOD_DEC_USE_COUNT(owner);
	up(&videodev_lock);
	return 0;
}

static int video_ioctl(struct inode *inode, struct file *file,
	unsigned int cmd, unsigned long arg)
{
	struct video_device *vfl = video_devdata(file);
	int err=vfl->ioctl(vfl, cmd, (void *)arg);

	if(err!=-ENOIOCTLCMD)
		return err;
	
	switch(cmd)
	{
		default:
			return -EINVAL;
	}
}

/*
 *	We need to do MMAP support
 */
  
int video_mmap(struct file *file, struct vm_area_struct *vma)
{
	int ret = -EINVAL;
	struct video_device *vfl = video_devdata(file);
	if(vfl->mmap) {
		lock_kernel();
		ret = vfl->mmap(vfl, (char *)vma->vm_start, 
				(unsigned long)(vma->vm_end-vma->vm_start));
		unlock_kernel();
	}
	return ret;
}

/*
 * helper function -- handles userspace copying for ioctl arguments
 */
int
video_usercopy(struct inode *inode, struct file *file,
	       unsigned int cmd, unsigned long arg,
	       int (*func)(struct inode *inode, struct file *file,
			   unsigned int cmd, void *arg))
{
	char	sbuf[128];
	void    *mbuf = NULL;
	void	*parg = NULL;
	int	err  = -EINVAL;

	/*  Copy arguments into temp kernel buffer  */
	switch (_IOC_DIR(cmd)) {
	case _IOC_NONE:
		parg = (void *)arg;
		break;
	case _IOC_READ: /* some v4l ioctls are marked wrong ... */
	case _IOC_WRITE:
	case (_IOC_WRITE | _IOC_READ):
		if (_IOC_SIZE(cmd) <= sizeof(sbuf)) {
			parg = sbuf;
		} else {
			/* too big to allocate from stack */
			mbuf = kmalloc(_IOC_SIZE(cmd),GFP_KERNEL);
			if (NULL == mbuf)
				return -ENOMEM;
			parg = mbuf;
		}
		
		err = -EFAULT;
		if (copy_from_user(parg, (void *)arg, _IOC_SIZE(cmd)))
			goto out;
		break;
	}

	/* call driver */
	err = func(inode, file, cmd, parg);
	if (err == -ENOIOCTLCMD)
		err = -EINVAL;
	if (err < 0)
		goto out;

	/*  Copy results into user buffer  */
	switch (_IOC_DIR(cmd))
	{
	case _IOC_READ:
	case (_IOC_WRITE | _IOC_READ):
		if (copy_to_user((void *)arg, parg, _IOC_SIZE(cmd)))
			err = -EFAULT;
		break;
	}

out:
	if (mbuf)
		kfree(mbuf);
	return err;
}

/*
 * open/release helper functions -- handle exclusive opens
 */
extern int video_exclusive_open(struct inode *inode, struct file *file)
{
	struct  video_device *vfl = video_devdata(file);
	int retval = 0;

	down(&vfl->lock);
	if (vfl->users) {
		retval = -EBUSY;
	} else {
		vfl->users++;
	}
	up(&vfl->lock);
	return retval;
}

extern int video_exclusive_release(struct inode *inode, struct file *file)
{
	struct  video_device *vfl = video_devdata(file);
	
	vfl->users--;
	return 0;
}

/*
 *	/proc support
 */

#if defined(CONFIG_PROC_FS) && defined(CONFIG_VIDEO_PROC_FS)

/* Hmm... i'd like to see video_capability information here, but
 * how can I access it (without changing the other drivers? -claudio
 */