[PATCH v4 3/3] scsi: ufs: rpmb: Drop the unregistered ufs_rpmb bus

[Stanley Jhu <stanleyjhu@google.com>]

ufs_rpmb_probe() assigns ufs_rpmb_bus_type to dev.bus, but that bus is
never passed to bus_register(). bus_add_device() rejects devices on an
unregistered bus, so device_register() has always failed:

  bus_add_device: cannot add device 'ufs_rpmb0' to unregistered bus
  'ufs_rpmb'
  ufshcd 0000:00:02.0: Failed to register UFS RPMB device 0

ufs_rpmb_probe() unwinds on the first failure, so no RPMB region has
ever been registered and /sys/bus/ufs_rpmb/devices/ has never been
populated.

ufs_rpmb_bus_type declares no .match and no .probe, and no driver binds
to it. RPMB devices are exposed to consumers through /sys/class/rpmb/,
which rpmb_dev_register() already sets up. Drop the bus rather than
register it: device_register() works with dev.bus left NULL given a
parent and a release callback, both of which ufs_rpmb_probe() sets.

With the bus gone, on a device advertising four RPMB regions:

  ufshcd 0000:00:02.0: UFS RPMB region 0 registered (capacity=32)
  ufshcd 0000:00:02.0: UFS RPMB region 1 registered (capacity=32)
  ufshcd 0000:00:02.0: UFS RPMB region 2 registered (capacity=32)
  ufshcd 0000:00:02.0: UFS RPMB region 3 registered (capacity=32)

/sys/class/rpmb then holds rpmb0 to rpmb3, and unbinding the host
removes them.

Fixes: b06b8c421485 ("scsi: ufs: core: Add OP-TEE based RPMB driver for UFS devices")
Signed-off-by: Stanley Jhu <stanleyjhu@google.com>
---
 drivers/ufs/core/ufs-rpmb.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/ufs/core/ufs-rpmb.c b/drivers/ufs/core/ufs-rpmb.c
index 373b60aba916..684fb37705c7 100644
--- a/drivers/ufs/core/ufs-rpmb.c
+++ b/drivers/ufs/core/ufs-rpmb.c
@@ -28,10 +28,6 @@
 #define UFS_RPMB_SEC_PROTOCOL		0xEC	/* JEDEC UFS application */
 #define UFS_RPMB_SEC_PROTOCOL_ID	0x01	/* JEDEC UFS RPMB protocol ID, CDB byte3 */
 
-static const struct bus_type ufs_rpmb_bus_type = {
-	.name = "ufs_rpmb",
-};
-
 /* UFS RPMB device structure */
 struct ufs_rpmb_dev {
 	u8 region_id;
@@ -208,7 +204,6 @@ int ufs_rpmb_probe(struct ufs_hba *hba)
 		ufs_rpmb->sdev = sdev;
 		ufs_rpmb->region_id = region;
 		ufs_rpmb->dev.parent = &sdev->sdev_gendev;
-		ufs_rpmb->dev.bus = &ufs_rpmb_bus_type;
 		ufs_rpmb->dev.release = ufs_rpmb_device_release;
 		dev_set_name(&ufs_rpmb->dev, "ufs_rpmb%d", region);
 
-- 
2.55.0.1007.g17ff1f9808-goog