[PATCH] ppc64: export vio_find_node()

To hotplug-remove virtual devices, we need vio_find_node() so we have a
pointer to pass to vio_unregister_device().

arch/ppc64/kernel/vio.c

@@ -29,6 +29,8 @@
 
 #define DBGENTER() pr_debug("%s entered\n", __FUNCTION__)
 
+extern struct subsystem devices_subsys; /* needed for vio_find_name() */
+
 struct iommu_table *vio_build_iommu_table(struct vio_dev *dev);
 
 static int vio_num_address_cells;
@@ -298,6 +300,42 @@ const void * vio_get_attribute(struct vio_dev *vdev, void* which, int* length)
 }
 EXPORT_SYMBOL(vio_get_attribute);
 
+/* vio_find_name() - internal because only vio.c knows how we formatted the
+ * kobject name
+ * XXX once vio_bus_type.devices is actually used as a kset in
+ * drivers/base/bus.c, this function should be removed in favor of
+ * "device_find(kobj_name, &vio_bus_type)"
+ */
+static struct vio_dev *vio_find_name(const char *kobj_name)
+{
+	struct kobject *found;
+
+	found = kset_find_obj(&devices_subsys.kset, kobj_name);
+	if (!found)
+		return NULL;
+
+	return to_vio_dev(container_of(found, struct device, kobj));
+}
+
+/**
+ * vio_find_node - find an already-registered vio_dev
+ * @vnode: device_node of the virtual device we're looking for
+ */
+struct vio_dev *vio_find_node(struct device_node *vnode)
+{
+	uint32_t *unit_address;
+	char kobj_name[BUS_ID_SIZE];
+
+	/* construct the kobject name from the device node */
+	unit_address = (uint32_t *)get_property(vnode, "reg", NULL);
+	if (!unit_address)
+		return NULL;
+	snprintf(kobj_name, BUS_ID_SIZE, "%x", *unit_address);
+
+	return vio_find_name(kobj_name);
+}
+EXPORT_SYMBOL(vio_find_node);
+
 /**
  * vio_build_iommu_table: - gets the dma information from OF and builds the TCE tree.
  * @dev: the virtual device.