On Mon, May 12, 2003 at 11:48:51AM -0700, Matt Porter wrote:
> request_msi() needs an additional parameter to specify which MSI
> it is hooking. A device can implement many messages in order to
> clarify which one of many events on a device has occurred. It
> may be desired to hook a separate handler for each of those to
> avoid another read of a status register.
Assuming that platform specific PCI setup does reasonable real to virtual
IRQ mapping, request_msi() is not needed. We can use pdev->irq
as "base" vector and MSI message number as offset. Alpha works this
way, BTW.
I think of something like this:
/**
* pci_using_msi - is this PCI device configured to use MSI?
* @dev: PCI device structure of device being queried
*
* Tells whether or not a PCI device is configured to use Message Signaled
* Interrupts. Returns number of allocated MSI messages, else 0.
*/
int
pci_using_msi(struct pci_dev *dev)
{
int msi = pci_find_capability(dev, PCI_CAP_ID_MSI);
u8 msgctl;
if (!msi || !dev->irq)
return 0;
pci_read_config_byte(dev, msi + PCI_MSI_FLAGS, &msgctl);
if (!(msgctl & PCI_MSI_FLAGS_ENABLE))
return 0;
return 1 << ((msgctl >> 4) & 7); /* # of messages allocated */
}
So that MSI-aware driver can do
nummsgs = pci_using_msi(dev);
if (!nummsgs)
goto no_msi;
for (msg = 0; msg < nummsgs; msg++) {
...
request_irq(dev->irq + msg, ...);
}
Ivan.
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This archive was generated by hypermail 2b29 : Thu May 15 2003 - 22:00:44 EST