From 57c2cf71c12318b72ebaa5720d210476b6bac4d4 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 11 Dec 2008 11:24:23 -0700 Subject: PCI: add pci_swizzle_interrupt_pin() This patch adds pci_swizzle_interrupt_pin(), which implements the INTx swizzling algorithm specified in Table 9-1 of the "PCI-to-PCI Bridge Architecture Specification," revision 1.2. There are many architecture-specific implementations of this swizzle that can be replaced by this common one. Reviewed-by: David Howells Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- drivers/pci/pci.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'drivers/pci/pci.c') diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index bd52ca4c289..d4d71fae623 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1366,6 +1366,20 @@ void pci_enable_ari(struct pci_dev *dev) bridge->ari_enabled = 1; } +/** + * pci_swizzle_interrupt_pin - swizzle INTx for device behind bridge + * @dev: the PCI device + * @pin: the INTx pin (1=INTA, 2=INTB, 3=INTD, 4=INTD) + * + * Perform INTx swizzling for a device behind one level of bridge. This is + * required by section 9.1 of the PCI-to-PCI bridge specification for devices + * behind bridges on add-in cards. + */ +u8 pci_swizzle_interrupt_pin(struct pci_dev *dev, u8 pin) +{ + return (((pin - 1) + PCI_SLOT(dev->devfn)) % 4) + 1; +} + int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge) { @@ -1376,7 +1390,7 @@ pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge) return -1; while (dev->bus->self) { - pin = (((pin - 1) + PCI_SLOT(dev->devfn)) % 4) + 1; + pin = pci_swizzle_interrupt_pin(dev, pin); dev = dev->bus->self; } *bridge = dev; -- cgit v1.2.3