uncached user space mapping with mmap() ???
Steven Scholz
steven.scholz at imc-berlin.de
Fri Mar 5 00:51:32 EST 2004
Hi there,
I am trying to access a hardware timer implemented in an FPGA from
user space. I implemented a simple mmap() functionality (taken from
Runbini's Linux Device Driver)
int simple_remap_mmap(struct file *filp, struct vm_area_struct *vma)
{
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
if (offset >= __pa(high_memory) || (filp->f_flags & O_SYNC)) {
vma->vm_flags |= VM_IO;
}
vma->vm_flags |= VM_RESERVED;
if (remap_page_range(vma->vm_start, offset,
vma->vm_end-vma->vm_start, vma->vm_page_prot))
return -EAGAIN;
return 0;
}
I just learned that
> getting an uncached user space mapping is architecture dependent.
> On ARM, however, passing pgprot_noncached(vma->vm_page_prot) to
> remap_page_range() will alter the page protections such that the
> mapping will be uncached.
How could I do this on an MPC8xx?
Thanks a million!
--
Steven Scholz
imc Measurement & Control imc Meßsysteme GmbH
Voltastr. 5 Voltastr. 5
13355 Berlin 13355 Berlin
Germany Deutschland
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
More information about the Linuxppc-embedded
mailing list