video-buf.c

这是一个市场上常见电视卡的驱动程序源代码

 done:
	up(&q->lock);
	return retval;
}

int videobuf_read_start(struct file *file, struct videobuf_queue *q)
{
	enum v4l2_field field;
	unsigned long flags;
	int count = 0, size = 0;
	int err, i;

	q->ops->buf_setup(file,&count,&size);
	if (count < 2)
		count = 2;
	if (count > VIDEO_MAX_FRAME)
		count = VIDEO_MAX_FRAME;
	size = PAGE_ALIGN(size);

	err = videobuf_mmap_setup(file, q, count, size, V4L2_MEMORY_USERPTR);
	if (err)
		return err;
	for (i = 0; i < count; i++) {
		field = videobuf_next_field(q);
		err = q->ops->buf_prepare(file,q->bufs[i],field);
		if (err)
			return err;
		list_add_tail(&q->bufs[i]->stream, &q->stream);
	}
	spin_lock_irqsave(q->irqlock,flags);
	for (i = 0; i < count; i++)
		q->ops->buf_queue(file,q->bufs[i]);
	spin_unlock_irqrestore(q->irqlock,flags);
	q->reading = 1;
	return 0;
}

void videobuf_read_stop(struct file *file, struct videobuf_queue *q)
{
	int i;
	
	videobuf_queue_cancel(file,q);
	INIT_LIST_HEAD(&q->stream);
	for (i = 0; i < VIDEO_MAX_FRAME; i++) {
		if (NULL == q->bufs[i])
			continue;
		kfree(q->bufs[i]);
		q->bufs[i] = NULL;
	}
	q->read_buf = NULL;
	q->reading  = 0;
}

ssize_t videobuf_read_stream(struct file *file, struct videobuf_queue *q,
			     char *data, size_t count, loff_t *ppos,
			     int vbihack)
{
	unsigned int *fc, bytes;
	int err, retval;
	unsigned long flags;
	
	down(&q->lock);
	retval = -EBUSY;
	if (q->streaming)
		goto done;
	if (!q->reading) {
		retval = videobuf_read_start(file,q);
		if (retval < 0)
			goto done;
	}

	retval = 0;
	while (count > 0) {
		/* get / wait for data */
		if (NULL == q->read_buf) {
			q->read_buf = list_entry(q->stream.next,
						 struct videobuf_buffer,
						 stream);
			list_del(&q->read_buf->stream);
			q->read_off = 0;
		}
		err = videobuf_waiton(q->read_buf,
				      file->f_flags & O_NONBLOCK,1);
		if (err < 0) {
			if (0 == retval)
				retval = err;
			break;
		}

		if (q->read_buf->state == STATE_DONE) {
			if (vbihack) {
				/* dirty, undocumented hack -- pass the frame counter
				 * within the last four bytes of each vbi data block.
				 * We need that one to maintain backward compatibility
				 * to all vbi decoding software out there ... */
				fc  = (unsigned int*)q->read_buf->dma.vmalloc;
				fc += (q->read_buf->size>>2) -1;
				*fc = q->read_buf->field_count >> 1;
				dprintk(1,"vbihack: %d\n",*fc);
			}
			
			/* copy stuff */
			bytes = count;
			if (bytes > q->read_buf->size - q->read_off)
				bytes = q->read_buf->size - q->read_off;
			if (copy_to_user(data + retval,
					 q->read_buf->dma.vmalloc + q->read_off,
					 bytes)) {
				if (0 == retval)
					retval = -EFAULT;
				break;
			}
			count       -= bytes;
			retval      += bytes;
			q->read_off += bytes;
		} else {
			/* some error */
			q->read_off = q->read_buf->size;
			if (0 == retval)
				retval = -EIO;
		}

		/* requeue buffer when done with copying */
		if (q->read_off == q->read_buf->size) {
			list_add_tail(&q->read_buf->stream,
				      &q->stream);
			spin_lock_irqsave(q->irqlock,flags);
			q->ops->buf_queue(file,q->read_buf);
			spin_unlock_irqrestore(q->irqlock,flags);
			q->read_buf = NULL;
		}
		if (retval < 0)
			break;
	}

 done:
	up(&q->lock);
	return retval;
}

unsigned int videobuf_poll_stream(struct file *file,
				  struct videobuf_queue *q,
				  poll_table *wait)
{
	struct videobuf_buffer *buf = NULL;
	unsigned int rc = 0;

	down(&q->lock);
	if (q->streaming) {
		if (!list_empty(&q->stream))
			buf = list_entry(q->stream.next,
					 struct videobuf_buffer, stream);
	} else {
		if (!q->reading)
			videobuf_read_start(file,q);
		if (!q->reading) {
			rc = POLLERR;
		} else if (NULL == q->read_buf) {
			q->read_buf = list_entry(q->stream.next,
						 struct videobuf_buffer,
						 stream);
			list_del(&q->read_buf->stream);
			q->read_off = 0;
		}
		buf = q->read_buf;
	}
	if (!buf)
		rc = POLLERR;

	if (0 == rc) {
		poll_wait(file, &buf->done, wait);
		if (buf->state == STATE_DONE ||
		    buf->state == STATE_ERROR)
			rc = POLLIN|POLLRDNORM;
	}
	up(&q->lock);
	return rc;
}

/* --------------------------------------------------------------------- */

static void
videobuf_vm_open(struct vm_area_struct *vma)
{
	struct videobuf_mapping *map = vma->vm_private_data;

	dprintk(2,"vm_open %p [count=%d,vma=%08lx-%08lx]\n",map,
		map->count,vma->vm_start,vma->vm_end);
	map->count++;
}

static void
videobuf_vm_close(struct vm_area_struct *vma)
{
	struct videobuf_mapping *map = vma->vm_private_data;
	int i;

	dprintk(2,"vm_close %p [count=%d,vma=%08lx-%08lx]\n",map,
		map->count,vma->vm_start,vma->vm_end);

	/* down(&fh->lock); FIXME */
	map->count--;
	if (0 == map->count) {
		dprintk(1,"munmap %p\n",map);
		for (i = 0; i < VIDEO_MAX_FRAME; i++) {
			if (NULL == map->q->bufs[i])
				continue;
			if (map->q->bufs[i])
				;
			if (map->q->bufs[i]->map != map)
				continue;
			map->q->bufs[i]->map   = NULL;
			map->q->bufs[i]->baddr = 0;
			map->q->ops->buf_release(vma->vm_file,map->q->bufs[i]);
		}
		kfree(map);
	}
	/* up(&fh->lock); FIXME */
	return;
}

/*
 * Get a anonymous page for the mapping.  Make sure we can DMA to that
 * memory location with 32bit PCI devices (i.e. don't use highmem for
 * now ...).  Bounce buffers don't work very well for the data rates
 * video capture has.
 */
static struct page*
videobuf_vm_nopage(struct vm_area_struct *vma, unsigned long vaddr,
		  int write_access)
{
	struct page *page;

	dprintk(3,"nopage: fault @ %08lx [vma %08lx-%08lx]\n",
		vaddr,vma->vm_start,vma->vm_end);
        if (vaddr > vma->vm_end)
		return NOPAGE_SIGBUS;
	page = alloc_page(GFP_USER);
	if (!page)
		return NOPAGE_OOM;
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,20)
	clear_user_page(page_address(page), vaddr);
#else
	clear_user_page(page_address(page), vaddr, page);
#endif
	return page;
}

static struct vm_operations_struct videobuf_vm_ops =
{
	.open     = videobuf_vm_open,
	.close    = videobuf_vm_close,
	.nopage   = videobuf_vm_nopage,
};

int videobuf_mmap_setup(struct file *file, struct videobuf_queue *q,
			unsigned int bcount, unsigned int bsize,
			enum v4l2_memory memory)
{
	unsigned int i;
	int err;

	err = videobuf_mmap_free(file,q);
	if (0 != err)
		return err;

	for (i = 0; i < bcount; i++) {
		q->bufs[i] = videobuf_alloc(q->msize);
		q->bufs[i]->i      = i;
		q->bufs[i]->memory = memory;
		q->bufs[i]->bsize  = bsize;
		switch (memory) {
		case V4L2_MEMORY_MMAP:
			q->bufs[i]->boff  = bsize * i;
			break;
		case V4L2_MEMORY_USERPTR:
		case V4L2_MEMORY_OVERLAY:
			/* nothing */
			break;
		};
	}
	dprintk(1,"mmap setup: %d buffers, %d bytes each\n",
		bcount,bsize);
	return 0;
}

int videobuf_mmap_free(struct file *file, struct videobuf_queue *q)
{
	int i;

	for (i = 0; i < VIDEO_MAX_FRAME; i++)
		if (q->bufs[i] && q->bufs[i]->map)
			return -EBUSY;
	for (i = 0; i < VIDEO_MAX_FRAME; i++) {
		if (NULL == q->bufs[i])
			continue;
		q->ops->buf_release(file,q->bufs[i]);
		kfree(q->bufs[i]);
		q->bufs[i] = NULL;
	}
	return 0;
}

int videobuf_mmap_mapper(struct vm_area_struct *vma,
			 struct videobuf_queue *q)
{
	struct videobuf_mapping *map;
	unsigned int first,last,size,i;
	int retval;

	down(&q->lock);
	retval = -EINVAL;
	if (!(vma->vm_flags & VM_WRITE)) {
		dprintk(1,"mmap app bug: PROT_WRITE please\n");
		goto done;
	}
	if (!(vma->vm_flags & VM_SHARED)) {
		dprintk(1,"mmap app bug: MAP_SHARED please\n");
		goto done;
	}

	/* look for first buffer to map */
	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
		if (NULL == q->bufs[first])
			continue;
		if (V4L2_MEMORY_MMAP != q->bufs[first]->memory)
			continue;
		if (q->bufs[first]->boff == (vma->vm_pgoff << PAGE_SHIFT))
			break;
	}
	if (VIDEO_MAX_FRAME == first) {
		dprintk(1,"mmap app bug: offset invalid [offset=0x%lx]\n",
			(vma->vm_pgoff << PAGE_SHIFT));
		goto done;
	}

	/* look for last buffer to map */
	for (size = 0, last = first; last < VIDEO_MAX_FRAME; last++) {
		if (NULL == q->bufs[last])
			continue;
		if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
			continue;
		if (q->bufs[last]->map) {
			retval = -EBUSY;
			goto done;
		}
		size += q->bufs[last]->bsize;
		if (size == (vma->vm_end - vma->vm_start))
			break;
	}
	if (VIDEO_MAX_FRAME == last) {
		dprintk(1,"mmap app bug: size invalid [size=0x%lx]\n",
			(vma->vm_end - vma->vm_start));
		goto done;
	}

	/* create mapping + update buffer list */
	retval = -ENOMEM;
	map = kmalloc(sizeof(struct videobuf_mapping),GFP_KERNEL);
	if (NULL == map)
		goto done;
	for (size = 0, i = first; i <= last; size += q->bufs[i++]->bsize) {
		q->bufs[i]->map   = map;
		q->bufs[i]->baddr = vma->vm_start + size;
	}
	map->count    = 1;
	map->start    = vma->vm_start;
	map->end      = vma->vm_end;
	map->q        = q;
	vma->vm_ops   = &videobuf_vm_ops;
	vma->vm_flags |= VM_DONTEXPAND;
	vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
	vma->vm_private_data = map;
	dprintk(1,"mmap %p: %08lx-%08lx pgoff %08lx bufs %d-%d\n",
		map,vma->vm_start,vma->vm_end,vma->vm_pgoff,first,last);
	retval = 0;

 done:
	up(&q->lock);
	return retval;
}

/* --------------------------------------------------------------------- */

EXPORT_SYMBOL_GPL(videobuf_vmalloc_to_sg);
EXPORT_SYMBOL_GPL(videobuf_lock);
EXPORT_SYMBOL_GPL(videobuf_unlock);

EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
EXPORT_SYMBOL_GPL(videobuf_dma_pci_map);
EXPORT_SYMBOL_GPL(videobuf_dma_pci_sync);
EXPORT_SYMBOL_GPL(videobuf_dma_pci_unmap);
EXPORT_SYMBOL_GPL(videobuf_dma_free);

EXPORT_SYMBOL_GPL(videobuf_alloc);
EXPORT_SYMBOL_GPL(videobuf_waiton);
EXPORT_SYMBOL_GPL(videobuf_iolock);

EXPORT_SYMBOL_GPL(videobuf_queue_init);
EXPORT_SYMBOL_GPL(videobuf_queue_cancel);
EXPORT_SYMBOL_GPL(videobuf_queue_is_busy);

EXPORT_SYMBOL_GPL(videobuf_next_field);
EXPORT_SYMBOL_GPL(videobuf_status);
EXPORT_SYMBOL_GPL(videobuf_reqbufs);
EXPORT_SYMBOL_GPL(videobuf_querybuf);
EXPORT_SYMBOL_GPL(videobuf_qbuf);
EXPORT_SYMBOL_GPL(videobuf_dqbuf);
EXPORT_SYMBOL_GPL(videobuf_streamon);
EXPORT_SYMBOL_GPL(videobuf_streamoff);

EXPORT_SYMBOL_GPL(videobuf_read_start);
EXPORT_SYMBOL_GPL(videobuf_read_stop);
EXPORT_SYMBOL_GPL(videobuf_read_stream);
EXPORT_SYMBOL_GPL(videobuf_read_one);
EXPORT_SYMBOL_GPL(videobuf_poll_stream);

EXPORT_SYMBOL_GPL(videobuf_mmap_setup);
EXPORT_SYMBOL_GPL(videobuf_mmap_free);
EXPORT_SYMBOL_GPL(videobuf_mmap_mapper);

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