IOCTL problem for network device

Hi all,
Iam writing PCI device driver for the custom board that is
registered as network driver "zzz0" using register_netdevice() that
does bus master DMA data transfer.
1. In my driver, I could do DMA transfer (filling dma memory in
the kernel itself) data between pc to board and vice versa by
programming the memory mapped device DMA register.
Now what I want is that,I want the user application to fill the
dma buffer area through IOCTL and to start the transfer.
Iam not clear with copy_from_user/ copy_to_user with mmap()
function. I hope using mmap gives high preformance. Let me know how to
use mmap to map kernelspace into user space.
hint will be helpfull.


2. Also,as I registered the device as network device, I could use
socket and interface name (zzz0) to open the device as I read from
rubini's virtual network interface.
But when I try to issue ioctl cmd , I get failed in
copy_from_user which gives no of bytes not copied error. I used the
following sample code.

int sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
struct zzz_userinfo info; /* configuration data in/out */
struct ifreq req;

strcpy(req.ifr_name, "zzz0");
req.ifr_data = (zzz)&info;

/* filled my info here*/

if (ioctl(sock, SIOCGDEVINFO, &req)<0) {
/* deal with error */
}


/* in kernel driver */
ptr = (struct zzz_userinfo *)ifr->ifr_data;
err = copy_from_user(&info, ptr, sizeof(info));
if (err)
{ printk(" not coiped %d",err); return err;}
/* deal with the information */
return 0;

whats wrong in the above code?
Hope somebody can help me on this.

Sara.