dv1394.c

IEE1394 火线接口驱动 for linux

		
		target_frame = video->first_clear_frame;
		
		spin_unlock_irqrestore(&video->spinlock, flags);

		if (video->frames[target_frame]->state == FRAME_CLEAR) {

			/* how much room is left in the target frame buffer */
			cnt = video->frame_size - (video->write_off - target_frame * video->frame_size);

		} else {
			/* buffer is already used */
			cnt = 0;
		}

		if (cnt > count)
			cnt = count;

		if (cnt <= 0) { 
			/* no room left, gotta wait */
			if (file->f_flags & O_NONBLOCK) {
				if (!ret)
					ret = -EAGAIN;
				break;
			}
			if (signal_pending(current)) {
				if (!ret)
					ret = -ERESTARTSYS;
				break;
			}

			schedule();
			
			continue; /* start over from 'while(count > 0)...' */
		}

		if (copy_from_user(video->dv_buf.kvirt + video->write_off, buffer, cnt)) {
			if (!ret)
				ret = -EFAULT;
			break;
		}

		video->write_off = (video->write_off + cnt) % (video->n_frames * video->frame_size);

		count -= cnt;
		buffer += cnt;
		ret += cnt;

		if (video->write_off == video->frame_size * ((target_frame + 1) % video->n_frames))
				frame_prepare(video, target_frame);
	}
	
	remove_wait_queue(&video->waitq, &wait);
	set_current_state(TASK_RUNNING);
	up(&video->sem);
	return ret;
}


static ssize_t dv1394_read(struct file *file,  char *buffer, size_t count, loff_t *ppos)
{
	struct video_card *video = file_to_video_card(file);
	DECLARE_WAITQUEUE(wait, current);
	ssize_t ret;
	size_t cnt;
	unsigned long flags;
	int target_frame;

	/* serialize this to prevent multi-threaded mayhem */
	if (file->f_flags & O_NONBLOCK) {
		if (down_trylock(&video->sem))
			return -EAGAIN;
	} else {
		if (down_interruptible(&video->sem))
			return -ERESTARTSYS;
	}

	if ( !video_card_initialized(video) ) {
		ret = do_dv1394_init_default(video);
		if (ret) {
			up(&video->sem);
			return ret;
		}
		video->continuity_counter = -1;
		
		receive_packets(video);
		
		start_dma_receive(video);
	}

	ret = 0;
	add_wait_queue(&video->waitq, &wait);

	while (count > 0) {

		/* must set TASK_INTERRUPTIBLE *before* checking for free
		   buffers; otherwise we could miss a wakeup if the interrupt
		   fires between the check and the schedule() */
		
		set_current_state(TASK_INTERRUPTIBLE);

		spin_lock_irqsave(&video->spinlock, flags);

		target_frame = video->first_clear_frame;

		spin_unlock_irqrestore(&video->spinlock, flags);

		if (target_frame >= 0 &&
			video->n_clear_frames > 0 &&
			video->frames[target_frame]->state == FRAME_CLEAR) {

			/* how much room is left in the target frame buffer */
			cnt = video->frame_size - (video->write_off - target_frame * video->frame_size);

		} else {
			/* buffer is already used */
			cnt = 0;
		}

		if (cnt > count)
			cnt = count;

		if (cnt <= 0) { 
			/* no room left, gotta wait */
			if (file->f_flags & O_NONBLOCK) {
				if (!ret)
					ret = -EAGAIN;
				break;
			}
			if (signal_pending(current)) {
				if (!ret)
					ret = -ERESTARTSYS;
				break;
			}

			schedule();
			
			continue; /* start over from 'while(count > 0)...' */
		}

		if (copy_to_user(buffer, video->dv_buf.kvirt + video->write_off, cnt)) {
				if (!ret)
					ret = -EFAULT;
				break;
		}

		video->write_off = (video->write_off + cnt) % (video->n_frames * video->frame_size);

		count -= cnt;
		buffer += cnt;
		ret += cnt;

		if (video->write_off == video->frame_size * ((target_frame + 1) % video->n_frames)) {
			spin_lock_irqsave(&video->spinlock, flags);
			video->n_clear_frames--;
			video->first_clear_frame = (video->first_clear_frame + 1) % video->n_frames;
			spin_unlock_irqrestore(&video->spinlock, flags);
		}
	}
	
	remove_wait_queue(&video->waitq, &wait);
	set_current_state(TASK_RUNNING);
	up(&video->sem);
	return ret;
}


/*** DEVICE IOCTL INTERFACE ************************************************/

/* I *think* the VFS serializes ioctl() for us, so we don't have to worry
   about situations like having two threads in here at once... */

static int dv1394_ioctl(struct inode *inode, struct file *file,
			   unsigned int cmd, unsigned long arg)
{
	struct video_card *video = file_to_video_card(file);
	unsigned long flags;
	int ret = -EINVAL;

	DECLARE_WAITQUEUE(wait, current);

	/* serialize this to prevent multi-threaded mayhem */
	if (file->f_flags & O_NONBLOCK) {
		if (down_trylock(&video->sem))
			return -EAGAIN;
	} else {
		if (down_interruptible(&video->sem))
			return -ERESTARTSYS;
	}

	switch(cmd)
	{
	case DV1394_SUBMIT_FRAMES:
	case DV1394_IOC_SUBMIT_FRAMES: {
		unsigned int n_submit;

		if ( !video_card_initialized(video) ) {
			ret = do_dv1394_init_default(video);
			if (ret)
				goto out;
		}

		n_submit = (unsigned int) arg;

		if (n_submit > video->n_frames) {
			ret = -EINVAL;
			goto out;
		}
			
		while (n_submit > 0) {

			add_wait_queue(&video->waitq, &wait);
			set_current_state(TASK_INTERRUPTIBLE);
				
			spin_lock_irqsave(&video->spinlock, flags);

			/* wait until video->first_clear_frame is really CLEAR */
			while (video->frames[video->first_clear_frame]->state != FRAME_CLEAR) {

				spin_unlock_irqrestore(&video->spinlock, flags);
					
				if (signal_pending(current)) {
					remove_wait_queue(&video->waitq, &wait);
					set_current_state(TASK_RUNNING);
					ret = -EINTR;
					goto out;
				}

				schedule();
				set_current_state(TASK_INTERRUPTIBLE);
				
				spin_lock_irqsave(&video->spinlock, flags);
			}
			spin_unlock_irqrestore(&video->spinlock, flags);

			remove_wait_queue(&video->waitq, &wait);
			set_current_state(TASK_RUNNING);
				
			frame_prepare(video, video->first_clear_frame);

			n_submit--;
		}

		ret = 0;
		break;
	}
	case DV1394_WAIT_FRAMES:
	case DV1394_IOC_WAIT_FRAMES: {
		unsigned int n_wait;

		if ( !video_card_initialized(video) ) {
			ret = -EINVAL;
			goto out;
		}
		
		n_wait = (unsigned int) arg;

		/* since we re-run the last frame on underflow, we will
		   never actually have n_frames clear frames; at most only
		   n_frames - 1 */

		if (n_wait > (video->n_frames-1) ) {
			ret = -EINVAL;
			goto out;
		}
			
		add_wait_queue(&video->waitq, &wait);
		set_current_state(TASK_INTERRUPTIBLE);
		
		spin_lock_irqsave(&video->spinlock, flags);

		while (video->n_clear_frames < n_wait) {
			
			spin_unlock_irqrestore(&video->spinlock, flags);
					
			if (signal_pending(current)) {
				remove_wait_queue(&video->waitq, &wait);
				set_current_state(TASK_RUNNING);
				ret = -EINTR;
				goto out;
			}

			schedule();
			set_current_state(TASK_INTERRUPTIBLE);
			
			spin_lock_irqsave(&video->spinlock, flags);
		}

		spin_unlock_irqrestore(&video->spinlock, flags);

		remove_wait_queue(&video->waitq, &wait);
		set_current_state(TASK_RUNNING);
		ret = 0;
		break;
	}
	case DV1394_RECEIVE_FRAMES:
	case DV1394_IOC_RECEIVE_FRAMES: {
		unsigned int n_recv;

		if ( !video_card_initialized(video) ) {
			ret = -EINVAL;
			goto out;
		}
		
		n_recv = (unsigned int) arg;

		/* at least one frame must be active */
		if (n_recv > (video->n_frames-1) ) {
			ret = -EINVAL;
			goto out;
		}
			
		spin_lock_irqsave(&video->spinlock, flags);

		/* release the clear frames */
		video->n_clear_frames -= n_recv;

		/* advance the clear frame cursor */
		video->first_clear_frame = (video->first_clear_frame + n_recv) % video->n_frames;

		/* reset dropped_frames */
		video->dropped_frames = 0;
			
		spin_unlock_irqrestore(&video->spinlock, flags);

		ret = 0;
		break;
	}
	case DV1394_START_RECEIVE:
	case DV1394_IOC_START_RECEIVE: {
		if ( !video_card_initialized(video) ) {
			ret = do_dv1394_init_default(video);
			if (ret)
				goto out;
		}
	
		video->continuity_counter = -1;
		
		receive_packets(video);
		
		start_dma_receive(video);

		ret = 0;
		break;
	}
	case DV1394_INIT:
	case DV1394_IOC_INIT: {
		struct dv1394_init init;
		if (arg == (unsigned long) NULL) {
			ret = do_dv1394_init_default(video);
		} else {
			if (copy_from_user(&init, (void*)arg, sizeof(init))) {
				ret = -EFAULT;
				goto out;
			}
			ret = do_dv1394_init(video, &init);
		}
		break;
	}
	case DV1394_SHUTDOWN:
	case DV1394_IOC_SHUTDOWN:
		do_dv1394_shutdown(video, 0);
		ret = 0;
		break;

	case DV1394_GET_STATUS:
        case DV1394_IOC_GET_STATUS: {
		struct dv1394_status status;

		if ( !video_card_initialized(video) ) {
			ret = -EINVAL;
			goto out;
		}

		status.init.api_version = DV1394_API_VERSION;
		status.init.channel = video->channel;
		status.init.n_frames = video->n_frames;
		status.init.format = video->pal_or_ntsc;
		status.init.cip_n = video->cip_n;
		status.init.cip_d = video->cip_d;
		status.init.syt_offset = video->syt_offset;

		status.first_clear_frame = video->first_clear_frame;

		/* the rest of the fields need to be locked against the interrupt */
		spin_lock_irqsave(&video->spinlock, flags);

		status.active_frame = video->active_frame;
		status.n_clear_frames = video->n_clear_frames;

		status.dropped_frames = video->dropped_frames;

		/* reset dropped_frames */
		video->dropped_frames = 0;
			
		spin_unlock_irqrestore(&video->spinlock, flags);

		if (copy_to_user((void*)arg, &status, sizeof(status))) {
			ret = -EFAULT;
			goto out;
		}

		ret = 0;
		break;
	}

	default:
		break;
	}

 out:
	up(&video->sem);
	return ret;
}



/*** DEVICE FILE INTERFACE CONTINUED ***************************************/

static int dv1394_open(struct inode *inode, struct file *file)
{
	struct video_card *video = NULL;

	/* if the device was opened through devfs, then file->private_data
	   has already been set to video by devfs */
	if (file->private_data) {
		video = (struct video_card*) file->private_data;
		
	} else {
		/* look up the card by ID */
		
		struct list_head *lh;
		unsigned long flags;
		
		spin_lock_irqsave(&dv1394_cards_lock, flags);
		if (!list_empty(&dv1394_cards)) {
			struct video_card *p;
			list_for_each(lh, &dv1394_cards) {
				p = list_entry(lh, struct video_card, list);
				if ((p->id) == ieee1394_file_to_instance(file)) {
					video = p;
					break;
				}
			}
		}
		spin_unlock_irqrestore(&dv1394_cards_lock, flags);

		if (!video) {
			debug_printk("dv1394: OHCI card %d not found", ieee1394_file_to_instance(file));
			return -ENODEV;
		}
		
		file->private_data = (void*) video;
	}
	
#ifndef DV1394_ALLOW_MORE_THAN_ONE_OPEN

	if ( test_and_set_bit(0, &video->open) ) {
		/* video is already open by someone else */
		return -EBUSY;
 	}