NAND flash memory-based storage devices use Flash Translation Layer (FTL) to translate logical addresses of I/O requests to corresponding flash memory addresses. Mobile storage devices typically have RAM with constrained size, thus lack in memory to keep the whole mapping table. Therefore, mapping tables are partially retrieved from NAND flash on demand, causing random-read performance degradation. To improve random read performance, JESD220-3 (HPB v1.0) proposes HPB (Host Performance Booster) which uses host system memory as a cache for the FTL mapping table. By using HPB, FTL data can be read from host memory faster than from NAND flash memory. The current version only supports the DCM (device control mode). This patch consists of 4 parts to support HPB feature. 1) UFS-feature layer 2) HPB probe and initialization process 3) READ -> HPB READ using cached map information 4) L2P (logical to physical) map management The UFS-feature is an additional layer to avoid the structure in which the UFS-core driver and the UFS-feature are entangled with each other in a single module. By adding the layer, UFS-features composed of various combinations can be supported. Also, even if a new feature is added, modification of the UFS-core driver can be minimized. In the HPB probe and init process, the device information of the UFS is queried. After checking supported features, the data structure for the HPB is initialized according to the device information. A read I/O in the active sub-region where the map is cached is changed to HPB READ by the HPB module. The HPB module manages the L2P map using information received from the device. For active sub-region, the HPB module caches through ufshpb_map request. For the in-active region, the HPB module discards the L2P map. When a write I/O occurs in an active sub-region area, associated dirty bitmap checked as dirty for preventing stale read. HPB is shown to have a performance improvement of 58 - 67% for random read workload. [1] This series patches are based on the 5.8/scsi-queue branch. [1]: https://www.usenix.org/conference/hotstorage17/program/presentation/jeong Changelog: v1 -> v2 1. Change sub-region context DS static allocation to dynamic allocation. 2. Change the full boilerplate text to SPDX style. 3. Other cleanups. Daejun park (5): scsi: ufs: Add UFS feature related parameter scsi: ufs: Add UFS feature layer scsi: ufs: Introduce HPB module scsi: ufs: L2P map management for HPB read scsi: ufs: Prepare HPB read for cached sub-region drivers/scsi/ufs/Kconfig | 9 + drivers/scsi/ufs/Makefile | 3 +- drivers/scsi/ufs/ufs.h | 12 + drivers/scsi/ufs/ufsfeature.c | 148 +++ drivers/scsi/ufs/ufsfeature.h | 69 ++ drivers/scsi/ufs/ufshcd.c | 19 + drivers/scsi/ufs/ufshcd.h | 3 + drivers/scsi/ufs/ufshpb.c | 1988 ++++++++++++++++++++++++++++++++++++ drivers/scsi/ufs/ufshpb.h | 234 +++++ 9 files changed, 2484 insertions(+), 1 deletion(-) created mode 100644 drivers/scsi/ufs/ufsfeature.c created mode 100644 drivers/scsi/ufs/ufsfeature.h created mode 100644 drivers/scsi/ufs/ufshpb.c created mode 100644 drivers/scsi/ufs/ufshpb.h
