1 files changed, 58 insertions, 0 deletions

diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index f907cfbfa13c..7f9eba9a0b02 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -303,6 +303,61 @@ void acpi_pci_irq_del_prt(struct pci_bus *bus)
 /* --------------------------------------------------------------------------
                           PCI Interrupt Routing Support
    -------------------------------------------------------------------------- */
+#ifdef CONFIG_X86_IO_APIC
+extern int noioapicquirk;
+extern int noioapicreroute;
+
+static int bridge_has_boot_interrupt_variant(struct pci_bus *bus)
+{
+        struct pci_bus *bus_it;
+
+        for (bus_it = bus ; bus_it ; bus_it = bus_it->parent) {
+                if (!bus_it->self)
+                        return 0;
+                if (bus_it->self->irq_reroute_variant)
+                        return bus_it->self->irq_reroute_variant;
+        }
+        return 0;
+}
+
+/*
+ * Some chipsets (e.g. Intel 6700PXH) generate a legacy INTx when the IRQ
+ * entry in the chipset's IO-APIC is masked (as, e.g. the RT kernel does
+ * during interrupt handling). When this INTx generation cannot be disabled,
+ * we reroute these interrupts to their legacy equivalent to get rid of
+ * spurious interrupts.
+ */
+static int acpi_reroute_boot_interrupt(struct pci_dev *dev,
+                                       struct acpi_prt_entry *entry)
+{
+        if (noioapicquirk || noioapicreroute) {
+                return 0;
+        } else {
+                switch (bridge_has_boot_interrupt_variant(dev->bus)) {
+                case 0:
+                        /* no rerouting necessary */
+                        return 0;
+                case INTEL_IRQ_REROUTE_VARIANT:
+                        /*
+                         * Remap according to INTx routing table in 6700PXH
+                         * specs, intel order number 302628-002, section
+                         * 2.15.2. Other chipsets (80332, ...) have the same
+                         * mapping and are handled here as well.
+                         */
+                        dev_info(&dev->dev, "PCI IRQ %d -> rerouted to legacy "
+                                 "IRQ %d\n", entry->index,
+                                 (entry->index % 4) + 16);
+                        entry->index = (entry->index % 4) + 16;
+                        return 1;
+                default:
+                        dev_warn(&dev->dev, "Cannot reroute IRQ %d to legacy "
+                                 "IRQ: unknown mapping\n", entry->index);
+                        return -1;
+                }
+        }
+}
+#endif /* CONFIG_X86_IO_APIC */
+
 static struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin)
 {
         struct acpi_prt_entry *entry;
@@ -311,6 +366,9 @@ static struct acpi_prt_entry *acpi_pci_irq_lookup(struct pci_dev *dev, int pin)
 
         entry = acpi_pci_irq_find_prt_entry(dev, pin);
         if (entry) {
+#ifdef CONFIG_X86_IO_APIC
+                acpi_reroute_boot_interrupt(dev, entry);
+#endif /* CONFIG_X86_IO_APIC */
                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %s[%c] _PRT entry\n",
                                   pci_name(dev), pin_name(pin)));
                 return entry;