mmap implementation... (problem with remapping!!)

Hello,

I have a problem about implementation of mmap for remapping a specific
I/O Region.

- mmap kernel routine:
        if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
        return -EINVAL;
    off = vma->vm_pgoff << PAGE_SHIFT;
    start = TPU_START;
    len = PAGE_ALIGN((start & ~PAGE_MASK)+TPU_SIZE);    
    if ((vma->vm_end - vma->vm_start + off) > len)
        return -EINVAL;
    off += start;
    vma->vm_pgoff = off >> PAGE_SHIFT;
    /* This is an IO map - tell maydump to skip this VMA */
    vma->vm_flags |= VM_IO;
    
      /* for PPC arch */
    pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE|_PAGE_GUARDED;
    
    if (io_remap_page_range(vma->vm_start, off, vma->vm_end -
vma->vm_start, vma->vm_page_prot))
        return -EAGAIN;

    return 0;


In user space I read always 0xFFFFFFFF in these registers after remapping.
I think that I made a mistake in this routine but I don't find it.
My scope is to remap some registers in userspace on a PPC embedded
architecture.
I don't have experience about this.

Please, could you help me?

teo_icKs.