PCI: add pci_common_swizzle() for INTx swizzling

This patch adds pci_common_swizzle(), which swizzles INTx values all the
way up to a root bridge.

This common implementation can replace several architecture-specific
ones.  This should someday be combined with pci_get_interrupt_pin(),
but I left it separate for now to make reviewing easier.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

2 files changed, 21 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 9d2aa6366fd0..c824dc8d617c 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1422,6 +1422,26 @@ pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge)
 }
 
 /**
+ * pci_common_swizzle - swizzle INTx all the way to root bridge
+ * @dev: the PCI device
+ * @pinp: pointer to the INTx pin value (1=INTA, 2=INTB, 3=INTD, 4=INTD)
+ *
+ * Perform INTx swizzling for a device.  This traverses through all PCI-to-PCI
+ * bridges all the way up to a PCI root bus.
+ */
+u8 pci_common_swizzle(struct pci_dev *dev, u8 *pinp)
+{
+        u8 pin = *pinp;
+
+        while (dev->bus->self) {
+                pin = pci_swizzle_interrupt_pin(dev, pin);
+                dev = dev->bus->self;
+        }
+        *pinp = pin;
+        return PCI_SLOT(dev->devfn);
+}
+
+/**
  *      pci_release_region - Release a PCI bar
  *      @pdev: PCI device whose resources were previously reserved by pci_request_region
  *      @bar: BAR to release
diff --git a/include/linux/pci.h b/include/linux/pci.h
index da1c22bab40e..170f9ae2d8a0 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -545,6 +545,7 @@ 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);
+u8 pci_common_swizzle(struct pci_dev *dev, u8 *pinp);
 extern struct pci_dev *pci_dev_get(struct pci_dev *dev);
 extern void pci_dev_put(struct pci_dev *dev);
 extern void pci_remove_bus(struct pci_bus *b);