1 files changed, 29 insertions, 7 deletions

diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
index efc0b5559ee0..2fce7738e9e2 100644
--- a/arch/powerpc/kernel/pci_64.c
+++ b/arch/powerpc/kernel/pci_64.c
@@ -21,13 +21,13 @@
 #include <linux/mm.h>
 #include <linux/list.h>
 #include <linux/syscalls.h>
+#include <linux/irq.h>
 
 #include <asm/processor.h>
 #include <asm/io.h>
 #include <asm/prom.h>
 #include <asm/pci-bridge.h>
 #include <asm/byteorder.h>
-#include <asm/irq.h>
 #include <asm/machdep.h>
 #include <asm/ppc-pci.h>
 
@@ -1289,15 +1289,37 @@ int pci_read_irq_line(struct pci_dev *pci_dev)
 
         DBG("Try to map irq for %s...\n", pci_name(pci_dev));
 
+        /* Try to get a mapping from the device-tree */
         if (of_irq_map_pci(pci_dev, &oirq)) {
-                DBG(" -> failed !\n");
-                return -1;
-        }
+                u8 line, pin;
+
+                /* If that fails, lets fallback to what is in the config
+                 * space and map that through the default controller. We
+                 * also set the type to level low since that's what PCI
+                 * interrupts are. If your platform does differently, then
+                 * either provide a proper interrupt tree or don't use this
+                 * function.
+                 */
+                if (pci_read_config_byte(pci_dev, PCI_INTERRUPT_PIN, &pin))
+                        return -1;
+                if (pin == 0)
+                        return -1;
+                if (pci_read_config_byte(pci_dev, PCI_INTERRUPT_LINE, &line) ||
+                    line == 0xff) {
+                        return -1;
+                }
+                DBG(" -> no map ! Using irq line %d from PCI config\n", line);
 
-        DBG(" -> got one, spec %d cells (0x%08x...) on %s\n",
-            oirq.size, oirq.specifier[0], oirq.controller->full_name);
+                virq = irq_create_mapping(NULL, line);
+                if (virq != NO_IRQ)
+                        set_irq_type(virq, IRQ_TYPE_LEVEL_LOW);
+        } else {
+                DBG(" -> got one, spec %d cells (0x%08x...) on %s\n",
+                    oirq.size, oirq.specifier[0], oirq.controller->full_name);
 
-        virq = irq_create_of_mapping(oirq.controller, oirq.specifier, oirq.size);
+                virq = irq_create_of_mapping(oirq.controller, oirq.specifier,
+                                             oirq.size);
+        }
         if(virq == NO_IRQ) {
                 DBG(" -> failed to map !\n");
                 return -1;