Commit 57c2cf71 authored by Bjorn Helgaas's avatar Bjorn Helgaas Committed by Jesse Barnes
Browse files

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: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent 12b955ff

drivers/pci/pci.c

+15 −1
Original line number Diff line number Diff line
@@ -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;

include/linux/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

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