videodev.c

一个2.4.21版本的嵌入式linux内核

/*
 * 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 */


/*
 *	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
 */
static int videodev_proc_read(char *page, char **start, off_t off,
			       int count, int *eof, void *data)
{
	char *out = page;
	struct video_device *vfd = data;
	struct videodev_proc_data *d;
	struct list_head *tmp;
	int len;
	char c = ' ';

	list_for_each (tmp, &videodev_proc_list) {
		d = list_entry(tmp, struct videodev_proc_data, proc_list);
		if (vfd == d->vdev)
			break;
	}

	/* Sanity check */
	if (tmp == &videodev_proc_list)
		goto skip;
		
#define PRINT_VID_TYPE(x) do { if (vfd->type & x) \
	out += sprintf (out, "%c%s", c, #x); c='|';} while (0)

	out += sprintf (out, "name            : %s\n", vfd->name);
	out += sprintf (out, "type            :");
		PRINT_VID_TYPE(VID_TYPE_CAPTURE);
		PRINT_VID_TYPE(VID_TYPE_TUNER);
		PRINT_VID_TYPE(VID_TYPE_TELETEXT);
		PRINT_VID_TYPE(VID_TYPE_OVERLAY);
		PRINT_VID_TYPE(VID_TYPE_CHROMAKEY);
		PRINT_VID_TYPE(VID_TYPE_CLIPPING);
		PRINT_VID_TYPE(VID_TYPE_FRAMERAM);
		PRINT_VID_TYPE(VID_TYPE_SCALES);
		PRINT_VID_TYPE(VID_TYPE_MONOCHROME);
		PRINT_VID_TYPE(VID_TYPE_SUBCAPTURE);
		PRINT_VID_TYPE(VID_TYPE_MPEG_DECODER);
		PRINT_VID_TYPE(VID_TYPE_MPEG_ENCODER);
		PRINT_VID_TYPE(VID_TYPE_MJPEG_DECODER);
		PRINT_VID_TYPE(VID_TYPE_MJPEG_ENCODER);
	out += sprintf (out, "\n");
	out += sprintf (out, "hardware        : 0x%x\n", vfd->hardware);
#if 0
	out += sprintf (out, "channels        : %d\n", d->vcap.channels);
	out += sprintf (out, "audios          : %d\n", d->vcap.audios);
	out += sprintf (out, "maxwidth        : %d\n", d->vcap.maxwidth);
	out += sprintf (out, "maxheight       : %d\n", d->vcap.maxheight);
	out += sprintf (out, "minwidth        : %d\n", d->vcap.minwidth);
	out += sprintf (out, "minheight       : %d\n", d->vcap.minheight);
#endif

skip:
	len = out - page;
	len -= off;
	if (len < count) {
		*eof = 1;
		if (len <= 0)
			return 0;
	} else
		len = count;

	*start = page + off;

	return len;
}

static void videodev_proc_create(void)
{
	video_proc_entry = create_proc_entry("video", S_IFDIR, &proc_root);

	if (video_proc_entry == NULL) {
		printk("video_dev: unable to initialise /proc/video\n");
		return;
	}

	video_proc_entry->owner = THIS_MODULE;
	video_dev_proc_entry = create_proc_entry("dev", S_IFDIR, video_proc_entry);

	if (video_dev_proc_entry == NULL) {
		printk("video_dev: unable to initialise /proc/video/dev\n");
		return;
	}

	video_dev_proc_entry->owner = THIS_MODULE;
}

#if defined(CONFIG_PROC_FS) && defined(CONFIG_VIDEO_PROC_FS)
static void videodev_proc_destroy(void)
{
	if (video_dev_proc_entry != NULL)
		remove_proc_entry("dev", video_proc_entry);

	if (video_proc_entry != NULL)
		remove_proc_entry("video", &proc_root);
}
#endif

static void videodev_proc_create_dev (struct video_device *vfd, char *name)
{
	struct videodev_proc_data *d;
	struct proc_dir_entry *p;

	if (video_dev_proc_entry == NULL)
		return;

	d = kmalloc (sizeof (struct videodev_proc_data), GFP_KERNEL);
	if (!d)
		return;

	p = create_proc_entry(name, S_IFREG|S_IRUGO|S_IWUSR, video_dev_proc_entry);
	if (!p)
		return;
	p->data = vfd;
	p->read_proc = videodev_proc_read;

	d->proc_entry = p;
	d->vdev = vfd;
	strcpy (d->name, name);

	/* How can I get capability information ? */

	list_add (&d->proc_list, &videodev_proc_list);
}

static void videodev_proc_destroy_dev (struct video_device *vfd)
{
	struct list_head *tmp;
	struct videodev_proc_data *d;

	list_for_each (tmp, &videodev_proc_list) {
		d = list_entry(tmp, struct videodev_proc_data, proc_list);
		if (vfd == d->vdev) {
			remove_proc_entry(d->name, video_dev_proc_entry);
			list_del (&d->proc_list);
			kfree(d);
			break;
		}
	}
}

#endif /* CONFIG_VIDEO_PROC_FS */

extern struct file_operations video_fops;

/**
 *	video_register_device - register video4linux devices
 *	@vfd:  video device structure we want to register
 *	@type: type of device to register
 *	@nr:   which device number (0 == /dev/video0, 1 == /dev/video1, ...
 *             -1 == first free)
 *	
 *	The registration code assigns minor numbers based on the type
 *	requested. -ENFILE is returned in all the device slots for this
 *	category are full. If not then the minor field is set and the
 *	driver initialize function is called (if non %NULL).
 *
 *	Zero is returned on success.
 *
 *	Valid types are
 *
 *	%VFL_TYPE_GRABBER - A frame grabber
 *
 *	%VFL_TYPE_VTX - A teletext device
 *
 *	%VFL_TYPE_VBI - Vertical blank data (undecoded)
 *
 *	%VFL_TYPE_RADIO - A radio card	
 */

int video_register_device(struct video_device *vfd, int type, int nr)
{
	int i=0;
	int base;
	int err;
	int end;
	char *name_base;
	char name[16];
	
	switch(type)
	{
		case VFL_TYPE_GRABBER:
			base=0;
			end=64;
			name_base = "video";
			break;
		case VFL_TYPE_VTX:
			base=192;
			end=224;
			name_base = "vtx";
			break;
		case VFL_TYPE_VBI:
			base=224;
			end=240;
			name_base = "vbi";
			break;
		case VFL_TYPE_RADIO:
			base=64;
			end=128;
			name_base = "radio";
			break;
		default:
			return -1;
	}

	/* pick a minor number */
	down(&videodev_lock);
	if (-1 == nr) {
		/* use first free */
		for(i=base;i<end;i++)
			if (NULL == video_device[i])
				break;
		if (i == end) {
			up(&videodev_lock);
			return -ENFILE;
		}
	} else {
		/* use the one the driver asked for */
		i = base+nr;
		if (NULL != video_device[i]) {
			up(&videodev_lock);
			return -ENFILE;
		}
	}
	video_device[i]=vfd;
	vfd->minor=i;
	up(&videodev_lock);

	/* The init call may sleep so we book the slot out
	   then call */
	MOD_INC_USE_COUNT;
	if(vfd->initialize) {
		err=vfd->initialize(vfd);
		if(err<0) {
			video_device[i]=NULL;
			MOD_DEC_USE_COUNT;
			return err;
		}
	}
	sprintf (name, "v4l/%s%d", name_base, i - base);
	/*
	 *	Start the device root only. Anything else
	 *	has serious privacy issues.
	 */
	vfd->devfs_handle =
		devfs_register (NULL, name, DEVFS_FL_DEFAULT,
				VIDEO_MAJOR, vfd->minor,
				S_IFCHR | S_IRUSR | S_IWUSR,
				&video_fops,
				NULL);
	init_MUTEX(&vfd->lock);
	
#if defined(CONFIG_PROC_FS) && defined(CONFIG_VIDEO_PROC_FS)
	sprintf (name, "%s%d", name_base, i - base);
	videodev_proc_create_dev (vfd, name);
#endif
	return 0;
}

/**
 *	video_unregister_device - unregister a video4linux device
 *	@vfd: the device to unregister
 *
 *	This unregisters the passed device and deassigns the minor
 *	number. Future open calls will be met with errors.
 */
 
void video_unregister_device(struct video_device *vfd)
{
	down(&videodev_lock);

	if(video_device[vfd->minor]!=vfd)
		panic("videodev: bad unregister");

#if defined(CONFIG_PROC_FS) && defined(CONFIG_VIDEO_PROC_FS)
	videodev_proc_destroy_dev (vfd);
#endif

	devfs_unregister (vfd->devfs_handle);
	video_device[vfd->minor]=NULL;
	MOD_DEC_USE_COUNT;
	up(&videodev_lock);
}


static struct file_operations video_fops=
{
	owner:		THIS_MODULE,
	llseek:		no_llseek,
	read:		video_read,
	write:		video_write,
	ioctl:		video_ioctl,
	mmap:		video_mmap,
	open:		video_open,
	release:	video_release,
	poll:		video_poll,
};

/*
 *	Initialise video for linux
 */
 
static int __init videodev_init(void)
{
	printk(KERN_INFO "Linux video capture interface: v1.00\n");
	if(devfs_register_chrdev(VIDEO_MAJOR,"video_capture", &video_fops))
	{
		printk("video_dev: unable to get major %d\n", VIDEO_MAJOR);
		return -EIO;
	}

#if defined(CONFIG_PROC_FS) && defined(CONFIG_VIDEO_PROC_FS)
	videodev_proc_create ();
#endif
	
	return 0;
}

static void __exit videodev_exit(void)
{
#if defined(CONFIG_PROC_FS) && defined(CONFIG_VIDEO_PROC_FS)
	videodev_proc_destroy ();
#endif
	devfs_unregister_chrdev(VIDEO_MAJOR, "video_capture");
}

module_init(videodev_init)
module_exit(videodev_exit)

EXPORT_SYMBOL(video_register_device);
EXPORT_SYMBOL(video_unregister_device);
EXPORT_SYMBOL(video_devdata);
EXPORT_SYMBOL(video_usercopy);
EXPORT_SYMBOL(video_exclusive_open);
EXPORT_SYMBOL(video_exclusive_release);

MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("Device registrar for Video4Linux drivers");
MODULE_LICENSE("GPL");


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