1 files changed, 36 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 7fdf324d5b51..e58908066b0e 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -154,6 +154,42 @@ void pcibios_free_controller(struct pci_controller *phb)
 EXPORT_SYMBOL_GPL(pcibios_free_controller);
 
 /*
+ * This function is used to call pcibios_free_controller()
+ * in a deferred manner: a callback from the PCI subsystem.
+ *
+ * _*DO NOT*_ call pcibios_free_controller() explicitly if
+ * this is used (or it may access an invalid *phb pointer).
+ *
+ * The callback occurs when all references to the root bus
+ * are dropped (e.g., child buses/devices and their users).
+ *
+ * It's called as .release_fn() of 'struct pci_host_bridge'
+ * which is associated with the 'struct pci_controller.bus'
+ * (root bus) - it expects .release_data to hold a pointer
+ * to 'struct pci_controller'.
+ *
+ * In order to use it, register .release_fn()/release_data
+ * like this:
+ *
+ * pci_set_host_bridge_release(bridge,
+ *                             pcibios_free_controller_deferred
+ *                             (void *) phb);
+ *
+ * e.g. in the pcibios_root_bridge_prepare() callback from
+ * pci_create_root_bus().
+ */
+void pcibios_free_controller_deferred(struct pci_host_bridge *bridge)
+{
+        struct pci_controller *phb = (struct pci_controller *)
+                                         bridge->release_data;
+
+        pr_debug("domain %d, dynamic %d\n", phb->global_number, phb->is_dynamic);
+
+        pcibios_free_controller(phb);
+}
+EXPORT_SYMBOL_GPL(pcibios_free_controller_deferred);
+
+/*
  * The function is used to return the minimal alignment
  * for memory or I/O windows of the associated P2P bridge.
  * By default, 4KiB alignment for I/O windows and 1MiB for