> 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)
There is no relationship between the address returned from ioremap and
what you pass into io_remap_page_range(). ioremap gives you a kernel
virtual address for the PCI address you remap. io_remap_page_range()
creates a userspace mapping in the same way, and you should pass in
the PCI address exactly the same way you pass in the PCI address into
ioremap. io_remap_pfn_range() takes a PFN ("page frame number"),
which is basically the PCI address you want to map divided by
PAGE_SIZE. The main reason for using PFNs is that they allow you to
map addresses above 4G even if sizeof long is only 4.
In your code:
> dev.pcibar2 = ioremap_nocache(resource,size);
> dev.region_start = dev.pcibar2 + offset; // RAM is at some offset
> from base
This gives you a kernel mapping that you can use with readl(),
writel() etc to access the PCI memory from the kernel.
To map to userspace, this:
> if (io_remap_page_range(vma, phyaddr, vma->vm_start, vsize,
> vma->vm_page_prot))
should use phyaddr as you have it here:
> // phyaddr = physical address of PCI memory area
This is just wrong:
> unsigned long phy = __pa(dev->region_start + off);
__pa() doesn't work on addresses returned from ioremap. Just use the
same resource address you passed into ioremap.
- R.
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