Hi Daejun,
>
> On Wed, 2020-12-16 at 11:45 +0900, Daejun Park wrote:
> > This is a patch for the HPB initialization and adds HPB function calls to
> > UFS core driver.
> >
> > NAND flash-based storage devices, including UFS, have mechanisms to
> > translate logical addresses of IO requests to the corresponding physical
> > addresses of the flash storage.
> > In UFS, Logical-address-to-Physical-address (L2P) map data, which is
> > required to identify the physical address for the requested IOs, can only
> > be partially stored in SRAM from NAND flash. Due to this partial loading,
> > accessing the flash address area where the L2P information for that address
> > is not loaded in the SRAM can result in serious performance degradation.
> >
> > The basic concept of HPB is to cache L2P mapping entries in host system
> > memory so that both physical block address (PBA) and logical block address
> > (LBA) can be delivered in HPB read command.
> > The HPB READ command allows to read data faster than a read command in UFS
> > since it provides the physical address (HPB Entry) of the desired logical
> > block in addition to its logical address. The UFS device can access the
> > physical block in NAND directly without searching and uploading L2P mapping
> > table. This improves read performance because the NAND read operation for
> > uploading L2P mapping table is removed.
> >
> > In HPB initialization, the host checks if the UFS device supports HPB
> > feature and retrieves related device capabilities. Then, some HPB
> > parameters are configured in the device.
> >
> > Reviewed-by: Bart Van Assche
> > Reviewed-by: Can Guo
> > Acked-by: Avri Altman
> > Tested-by: Bean Huo
> > Signed-off-by: Daejun Park
> > ---
> > Documentation/ABI/testing/sysfs-driver-ufs | 80 +++
> > drivers/scsi/ufs/Kconfig | 9 +
> > drivers/scsi/ufs/Makefile | 1 +
> > drivers/scsi/ufs/ufs-sysfs.c | 18 +
> > drivers/scsi/ufs/ufs.h | 13 +
> > drivers/scsi/ufs/ufshcd.c | 48 ++
> > drivers/scsi/ufs/ufshcd.h | 23 +-
> > drivers/scsi/ufs/ufshpb.c | 562 +
> > drivers/scsi/ufs/ufshpb.h | 167 ++
> > 9 files changed, 920 insertions(+), 1 deletion(-)
> > create mode 100644 drivers/scsi/ufs/ufshpb.c
> > create mode 100644 drivers/scsi/ufs/ufshpb.h
> >
> > diff --git a/Documentation/ABI/testing/sysfs-driver-ufs
> > b/Documentation/ABI/testing/sysfs-driver-ufs
> > index d1a352194d2e..8b16a353392c 100644
> > --- a/Documentation/ABI/testing/sysfs-driver-ufs
> > +++ b/Documentation/ABI/testing/sysfs-driver-ufs
> > @@ -1019,3 +1019,83 @@ Contact: Asutosh Das
> > Description: This entry shows the configured size of WriteBooster
> > buffer.
> > 0400h corresponds to 4GB.
> > The file is read only.
> > +
> > +What:
> > /sys/bus/platform/drivers/ufshcd/*/device_descriptor/hpb_version
> > +Date: December 2020
> > +Contact: Daejun Park
> > +Description: This entry shows the HPB specification version.
> > + The full information about the descriptor could be found at UFS
> > + HPB (Host Performance Booster) Extension specifications.
> > + Example: version 1.2.3 = 0123h
> > + The file is read only.
> > +
> > +What:
> > /sys/bus/platform/drivers/ufshcd/*/device_descriptor/hpb_control
> > +Date: December 2020
> > +Contact: Daejun Park
> > +Description: This entry shows an indication of the HPB control mode.
> > + 00h: Host control mode
> > + 01h: Device control mode
> > + The file is read only.
> > +
> > +What:
> > /sys/bus/platform/drivers/ufshcd/*/geometry_descriptor/hpb_region_size
> > +Date: December 2020
> > +Contact: Daejun Park
> > +Description: This entry shows the bHPBRegionSize which can be
> > calculated
> > + as in the following (in bytes):
> > + HPB Region size = 512B * 2^bHPBRegionSize
> > + The file is read only.
> > +
> > +What:
> > /sys/bus/platform/drivers/ufshcd/*/geometry_descriptor/hpb_number_lu
> > +Date: December 2020
> > +Contact: Daejun Park
> > +Description: This entry shows the maximum number of HPB LU supported
> > by
> > + the device.
> > + 00h: HPB is not supported by the device.
> > + 01h ~ 20h: Maximum number of HPB LU supported by the device
> > + The file is read only.
> > +
> > +What:
> > /sys/bus/platform/drivers/ufshcd/*/geometry_descriptor/hpb_number_lu
> > +Date: December 2020
> > +Contact: Daejun Park
> > +Description: This entry shows the maximum number of HPB LU supported
> > by
> > + the device.
> > + 00h: HPB is not supported by the device.
> > + 01h ~ 20h:
