1 files changed, 48 insertions, 0 deletions

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index a83ee0b85394..eed67d9e73bc 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -151,6 +151,54 @@ void pci_enable_bridges(struct pci_bus *bus)
         }
 }
 
+/** pci_walk_bus - walk devices on/under bus, calling callback.
+ *  @top      bus whose devices should be walked
+ *  @cb       callback to be called for each device found
+ *  @userdata arbitrary pointer to be passed to callback.
+ *
+ *  Walk the given bus, including any bridged devices
+ *  on buses under this bus.  Call the provided callback
+ *  on each device found.
+ */
+void pci_walk_bus(struct pci_bus *top, void (*cb)(struct pci_dev *, void *),
+                  void *userdata)
+{
+        struct pci_dev *dev;
+        struct pci_bus *bus;
+        struct list_head *next;
+
+        bus = top;
+        spin_lock(&pci_bus_lock);
+        next = top->devices.next;
+        for (;;) {
+                if (next == &bus->devices) {
+                        /* end of this bus, go up or finish */
+                        if (bus == top)
+                                break;
+                        next = bus->self->bus_list.next;
+                        bus = bus->self->bus;
+                        continue;
+                }
+                dev = list_entry(next, struct pci_dev, bus_list);
+                pci_dev_get(dev);
+                if (dev->subordinate) {
+                        /* this is a pci-pci bridge, do its devices next */
+                        next = dev->subordinate->devices.next;
+                        bus = dev->subordinate;
+                } else
+                        next = dev->bus_list.next;
+                spin_unlock(&pci_bus_lock);
+
+                /* Run device routines with the bus unlocked */
+                cb(dev, userdata);
+
+                spin_lock(&pci_bus_lock);
+                pci_dev_put(dev);
+        }
+        spin_unlock(&pci_bus_lock);
+}
+EXPORT_SYMBOL_GPL(pci_walk_bus);
+
 EXPORT_SYMBOL(pci_bus_alloc_resource);
 EXPORT_SYMBOL_GPL(pci_bus_add_device);
 EXPORT_SYMBOL(pci_bus_add_devices);