powerpc/pci: Move pci_find_bus_by_node() around

This moves pci_find_bus_by_node() from arch/powerpc/platforms/
pseries/pci_dlpar.c to arch/powerpc/kernel/pci-hotplug.c so that
the function can be used by pSeries and PowerNV platform at the
same time. Also, below cleanup applied. No functional changes
introduced.

   * Remove variable "busdn" in find_bus_among_children()
   * Use PCI_DN() to convert device node to pci_dn

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 29 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/pci-hotplug.c b/arch/powerpc/kernel/pci-hotplug.c
index 2d108e541819..46587a14dd94 100644
--- a/arch/powerpc/kernel/pci-hotplug.c
+++ b/arch/powerpc/kernel/pci-hotplug.c
@@ -21,6 +21,35 @@
 #include <asm/firmware.h>
 #include <asm/eeh.h>
 
+static struct pci_bus *find_bus_among_children(struct pci_bus *bus,
+                                               struct device_node *dn)
+{
+        struct pci_bus *child = NULL;
+        struct pci_bus *tmp;
+
+        if (pci_bus_to_OF_node(bus) == dn)
+                return bus;
+
+        list_for_each_entry(tmp, &bus->children, node) {
+                child = find_bus_among_children(tmp, dn);
+                if (child)
+                        break;
+        }
+
+        return child;
+}
+
+struct pci_bus *pci_find_bus_by_node(struct device_node *dn)
+{
+        struct pci_dn *pdn = PCI_DN(dn);
+
+        if (!pdn  || !pdn->phb || !pdn->phb->bus)
+                return NULL;
+
+        return find_bus_among_children(pdn->phb->bus, dn);
+}
+EXPORT_SYMBOL_GPL(pci_find_bus_by_node);
+
 /**
  * pcibios_release_device - release PCI device
  * @dev: PCI device