I am writing a driver to map a PCI board memory space (pcibar2) into a
user-space vma via 'mmap'. What is the relationship between the address
returned from ioremap and the type of address needed in the
'io_remap_page_range' or 'remap_pfn_range' functions? How about the
following? (I am developing under RHEL4 and a 2.6.9 kernel)
In the 'init' part of the driver:
dev.pcibar2 = ioremap_nocache(resource,size);
dev.region_start = dev.pcibar2 + offset; // RAM is at some offset
from base
dev.region_size = <some size>
In the mydriver_mmap function:
static ssize_t mydriver_mmap (struct file *filp,
struct vm_area_struct
*vma)
{
// off = convert vm_pgoff back to user-space mmap 'off' value
// phyaddr = physical address of PCI memory area
// vsize = total size of area user wants to map
// psize = total avail size in device
struct mydriver_dev *dev = filp->private_data;
unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
unsigned long phy = __pa(dev->region_start + off);
unsigned long vsize = vma->vm_end - vma->vm_start;
unsigned long psize = dev->region_size - off;
if (vsize > psize)
return -EINVAL; /* spans too high */
if (io_remap_page_range(vma, phyaddr, vma->vm_start, vsize,
vma->vm_page_prot))
return -EAGAIN;
vma->vm_ops = &mydriver_vm_ops;
vma->vm_flags |= VM_IO | VM_RESERVED;
mydriver_vma_open(vma);
return 0;
}
--
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