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| author | Bjorn Helgaas <bjorn.helgaas@hp.com> | 2008-12-11 19:24:23 +0100 |
|---|---|---|
| committer | Jesse Barnes <jbarnes@virtuousgeek.org> | 2009-01-07 20:12:50 +0100 |
| commit | 57c2cf71c12318b72ebaa5720d210476b6bac4d4 (patch) | |
| tree | ba071276800dc24d9232fd124c4678b2a86f86b5 /drivers/pci/pci.c | |
| parent | x86/PCI: minor logic simplications (diff) | |
| download | linux-57c2cf71c12318b72ebaa5720d210476b6bac4d4.tar.xz linux-57c2cf71c12318b72ebaa5720d210476b6bac4d4.zip | |
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 <dhowells@redhat.com>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'drivers/pci/pci.c')
| -rw-r--r-- | drivers/pci/pci.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index bd52ca4c2893..d4d71fae6233 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; |