On 10/2/07, yogeshwar sonawane <yogyas@xxxxxxxxx> wrote:
> Hello all,
>
> For accessing memory-mapped 64bit-BAR regions of a PCI card, the
> respective BAR regions has to be made accessible to the kernel using
> ioremap() function.
> Then readl()/writel() are working fine on the address returned by ioremap().
> This is working in linux-2.6.9.
Here is an extraction from 2.6.23-rc5/drivers/pci/msi.c that
illustrate exactly what you have been saying (my remarks in ***):
static int msix_capability_init(struct pci_dev *dev,
struct msix_entry *entries, int nvec)
{
void __iomem *base;
*** first pci_resource_start() is to get the physical address
phys_addr = pci_resource_start (dev, bir) + table_offset;
*** then ioremap() is applied to convert it to virtual address
base = ioremap_nocache(phys_addr, nr_entries * PCI_MSIX_ENTRY_SIZE);
*** then assign to the structure
entry->mask_base = base;
And in the following function readl() and writel() are shown:
static void msix_flush_writes(unsigned int irq)
{
int offset = entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +
PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET;
***Here below is shown how readl() is applied to the virtual address mask_base
readl(entry->mask_base + offset);
static int msi_free_irqs(struct pci_dev* dev)
{
list_for_each_entry_safe(entry, tmp, &dev->msi_list, list) {
if (entry->msi_attrib.type == PCI_CAP_ID_MSIX) {
*** Here writel() is applied to the virtual address mask_base.
writel(1, entry->mask_base + entry->msi_attrib.entry_nr
* PCI_MSIX_ENTRY_SIZE
+ PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
if (list_is_last(&entry->list, &dev->msi_list))
iounmap(entry->mask_base);
*** The mask_base is here unmap, since it has been ioremap() earlier.
Beyond this point, the virtual address mask_base can therefore not
be used to write anymore.
}
list_del(&entry->list);
kfree(entry);
}
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