powerpc/pci: Add a platform hook after probe and before resource survey

Some platforms need to perform resource allocation using a custom algorithm
due to HW constraints, or may want to tweak things globally below a host
bridge. For example OPAL support for IODA will need to perform a
resource allocation pass that applies IODA specific segmentation
constraints to MMIO which cannot be done simply using the kernel generic
resource management code.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/machdep.h

@@ -213,6 +213,9 @@ struct machdep_calls {
 	 * allow assignment/enabling of the device. */
 	int  (*pcibios_enable_device_hook)(struct pci_dev *);
 
+	/* Called after scan and before resource survey */
+	void (*pcibios_fixup_phb)(struct pci_controller *hose);
+
 	/* Called to shutdown machine specific hardware not already controlled
 	 * by other drivers.
 	 */

arch/powerpc/kernel/pci-common.c

@@ -1732,6 +1732,12 @@ void __devinit pcibios_scan_phb(struct pci_controller *hose)
 	if (mode == PCI_PROBE_NORMAL)
 		hose->last_busno = bus->subordinate = pci_scan_child_bus(bus);
 
+	/* Platform gets a chance to do some global fixups before
+	 * we proceed to resource allocation
+	 */
+	if (ppc_md.pcibios_fixup_phb)
+		ppc_md.pcibios_fixup_phb(hose);
+
 	/* Configure PCI Express settings */
 	if (bus && !pci_has_flag(PCI_PROBE_ONLY)) {
 		struct pci_bus *child;