1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index ec395a6baf9c..a00d006d4c3a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2170,6 +2170,15 @@ int spi_register_controller(struct spi_controller *ctlr)
                 if (WARN(id < 0, "couldn't get idr"))
                         return id;
                 ctlr->bus_num = id;
+        } else {
+                /* devices with a fixed bus num must check-in with the num */
+                mutex_lock(&board_lock);
+                id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
+                        ctlr->bus_num + 1, GFP_KERNEL);
+                mutex_unlock(&board_lock);
+                if (WARN(id < 0, "couldn't get idr"))
+                        return id == -ENOSPC ? -EBUSY : id;
+                ctlr->bus_num = id;
         }
         INIT_LIST_HEAD(&ctlr->queue);
         spin_lock_init(&ctlr->queue_lock);