DMA into User space

Hi all,
Iam writing PCI device driver for the custom board registered as
network driver that does bus master DMA data transfer.
In my driver, I could do DMA transfer data between pc to board
and vice versa.Now what I want is that, after transfer from PCI device
to pc's dma memory, I want the user space application to access this
recevied dma buffer area through IOCTL.
Iam little bit confused using copy_from_user/copy_to_user
function along with mmap.
I hope using mmap() kernel space to user space gives good
preformance and I would like to know how to use it.
Hope somebody can help me on this.

Sara.