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PCI: add pci_swizzle_interrupt_pin()

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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>
This commit is contained in:
Bjorn Helgaas 2008-12-11 11:24:23 -07:00 committed by Jesse Barnes
parent 12b955ff63
commit 57c2cf71c1
2 changed files with 16 additions and 1 deletions
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16
drivers/pci/pci.c
View file

@ -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;

1
include/linux/pci.h
View file

@ -532,6 +532,7 @@ int __must_check pci_bus_add_device(struct pci_dev *dev);
void pci_read_bridge_bases(struct pci_bus *child);
struct resource *pci_find_parent_resource(const struct pci_dev *dev,
struct resource *res);
u8 pci_swizzle_interrupt_pin(struct pci_dev *dev, u8 pin);
int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge);
extern struct pci_dev *pci_dev_get(struct pci_dev *dev);
extern void pci_dev_put(struct pci_dev *dev);