[POWERPC] Disable PCI IO/Mem on a device when resources can't be allocated

This patch changes the PowerPC PCI code to disable IO and/or Memory
decoding on a PCI device when a resource of that type failed to be
allocated.  This is done to avoid having unallocated dangling BARs
enabled that might try to decode on top of other devices.

If a proper resource is assigned later on, then pci_enable_device()
will take care of re-enabling decoding.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/pci-common.c

@@ -1034,7 +1034,7 @@ clear_resource:
 	}
 }
 
-static inline void __devinit alloc_resource(struct pci_dev *dev, int idx)
+static inline int __devinit alloc_resource(struct pci_dev *dev, int idx)
 {
 	struct resource *pr, *r = &dev->resource[idx];
 
@@ -1058,7 +1058,10 @@ static inline void __devinit alloc_resource(struct pci_dev *dev, int idx)
 		r->flags |= IORESOURCE_UNSET;
 		r->end -= r->start;
 		r->start = 0;
+
+		return -EBUSY;
 	}
+	return 0;
 }
 
 static void __init pcibios_allocate_resources(int pass)
@@ -1080,8 +1083,12 @@ static void __init pcibios_allocate_resources(int pass)
 				disabled = !(command & PCI_COMMAND_IO);
 			else
 				disabled = !(command & PCI_COMMAND_MEMORY);
-			if (pass == disabled)
-				alloc_resource(dev, idx);
+			if (pass == disabled && alloc_resource(dev, idx)) {
+				command &= ~(r->flags & (IORESOURCE_IO |
+							 IORESOURCE_MEM));
+				pci_write_config_word(dev,
+						      PCI_COMMAND, command);
+			}
 		}
 		if (pass)
 			continue;