powerpc/pci: fix PCI-e devices rescan issue on powerpc platform

Powerpc initializes the DMA and IRQ information in pci_scan_child_bus()->
pcibios_fixup_bus()->pcibios_setup_bus_devices(). But for the devices
which are hotpluged, bus->is added has been set for the first scan of the
PCI-e bus, so the initialization code won't be called. Then the hotpluged
devices' driver will fail to load.

For example :
The PCI-e device 0001:03:00.0 is the Intel PCI-e e1000e network card, remove
it from the system:

    # echo 1 > /sys/bus/pci/devices/0001\:03\:00.0/remove
    # e1000e 0001:03:00.0 eth0: removed PHC

Rescan it from it's bus:

    # echo 1 > /sys/bus/pci/devices/0001\:02\:00.0/rescan
    ...
    e1000e 0001:03:00.0: Disabling ASPM L0s L1
    e1000e 0001:03:00.0: No usable DMA configuration, aborting
    e1000e: probe of 0001:03:00.0 failed with error -5

So we move the DMA & IRQ initialization code from pcibios_setup_devices() and
construct a new function pcibios_enable_device. We call this function in
pcibios_enable_device, which will be called by PCI-e rescan code. At the
meanwhile, we avoid the the impact on cardbus. I also validate this patch with
silicon's PCIe-sata which encounters the IRQ issue.
Signed-off-by: Yuanquan Chen <Yuanquan.Chen@freescale.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Hiroo Matsumoto <matsumoto.hiroo@jp.fujitsu.com>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>

arch/powerpc/kernel/pci-common.c

@@ -1023,20 +1023,8 @@ void pcibios_setup_bus_self(struct pci_bus *bus)
 		ppc_md.pci_dma_bus_setup(bus);
 }
 
-void pcibios_setup_bus_devices(struct pci_bus *bus)
+void pcibios_setup_device(struct pci_dev *dev)
 {
-	struct pci_dev *dev;
-
-	pr_debug("PCI: Fixup bus devices %d (%s)\n",
-		 bus->number, bus->self ? pci_name(bus->self) : "PHB");
-
-	list_for_each_entry(dev, &bus->devices, bus_list) {
-		/* Cardbus can call us to add new devices to a bus, so ignore
-		 * those who are already fully discovered
-		 */
-		if (dev->is_added)
-			continue;
-
 	/* Fixup NUMA node as it may not be setup yet by the generic
 	 * code and is needed by the DMA init
 	 */
@@ -1054,6 +1042,23 @@ void pcibios_setup_bus_devices(struct pci_bus *bus)
 	pci_read_irq_line(dev);
 	if (ppc_md.pci_irq_fixup)
 		ppc_md.pci_irq_fixup(dev);
+}
+
+void pcibios_setup_bus_devices(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+
+	pr_debug("PCI: Fixup bus devices %d (%s)\n",
+		 bus->number, bus->self ? pci_name(bus->self) : "PHB");
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		/* Cardbus can call us to add new devices to a bus, so ignore
+		 * those who are already fully discovered
+		 */
+		if (dev->is_added)
+			continue;
+
+		pcibios_setup_device(dev);
 	}
 }
 
@@ -1494,6 +1499,10 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
 		if (ppc_md.pcibios_enable_device_hook(dev))
 			return -EINVAL;
 
+	/* avoid pcie irq fix up impact on cardbus */
+	if (dev->hdr_type != PCI_HEADER_TYPE_CARDBUS)
+		pcibios_setup_device(dev);
+
 	return pci_enable_resources(dev, mask);
 }