The ufs_rpmb bus isn't registered in the device framework, so any
attempt to register RPMB devices on UFS will fail with:

 bus_add_device: cannot add device 'ufs_rpmb0' to unregistered bus 'ufs_rpmb'
 ufshcd-qcom 1d84000.ufshc: Failed to register UFS RPMB device 0

Add module_init() / exit() functions to handle bus registration and
unregistration.

Fixes: b06b8c421485 ("scsi: ufs: core: Add OP-TEE based RPMB driver for UFS devices")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
---
 drivers/ufs/core/ufs-rpmb.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/ufs/core/ufs-rpmb.c b/drivers/ufs/core/ufs-rpmb.c
index 50ef63afd528..8ae917adbc98 100644
--- a/drivers/ufs/core/ufs-rpmb.c
+++ b/drivers/ufs/core/ufs-rpmb.c
@@ -275,5 +275,18 @@ void ufs_rpmb_remove(struct ufs_hba *hba)
 	dev_info(hba->dev, "All UFS RPMB devices unregistered\n");
 }
 
+static int __init ufs_rpmb_init(void)
+{
+	return bus_register(&ufs_rpmb_bus_type);
+}
+
+static void __exit ufs_rpmb_exit(void)
+{
+	bus_unregister(&ufs_rpmb_bus_type);
+}
+
+module_init(ufs_rpmb_init);
+module_exit(ufs_rpmb_exit);
+
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("OP-TEE UFS RPMB driver");

---
base-commit: 3f2425f5b5bbbdd991ca9cdfd5502e68d8895998
change-id: 20260511-fix-ufs-rpmb-487d73d091b7

Best regards,
--  
With best wishes
Dmitry

On Sun, 20 Sep 2026 17:50:18 +0300, Dmitry Baryshkov wrote:
> The ufs_rpmb bus isn't registered in the device framework, so any
> attempt to register RPMB devices on UFS will fail with:
>
>  bus_add_device: cannot add device 'ufs_rpmb0' to unregistered bus 'ufs_rpmb'
>  ufshcd-qcom 1d84000.ufshc: Failed to register UFS RPMB device 0
>
> Add module_init() / exit() functions to handle bus registration and
> unregistration.

We have an existing patch on the list addressing this from the opposite
direction (`[PATCH v5 3/3]`, Reviewed-by Bean Huo) [1]:

Since ufs_rpmb_bus_type declares no .match and no .probe and consumers
access RPMB devices via /sys/class/rpmb/, patch 3/3 drops
ufs_rpmb_bus_type (leaving ufs_rpmb->dev.bus NULL) rather than
registering an empty bus.

Could you take a look at [1] and let us know which approach you prefer?

[1] https://lore.kernel.org/linux-scsi/20260914144943.2571104-1-stanleyjhu@google.com/