diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/scsi/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/scsi/ufs.rst (renamed from Documentation/scsi/ufs.txt) | 84 |
2 files changed, 55 insertions, 30 deletions
diff --git a/Documentation/scsi/index.rst b/Documentation/scsi/index.rst index df005cb94f6b..27720d145eff 100644 --- a/Documentation/scsi/index.rst +++ b/Documentation/scsi/index.rst @@ -44,5 +44,6 @@ Linux SCSI Subsystem sym53c500_cs sym53c8xx_2 tcm_qla2xxx + ufs scsi_transport_srp/figures diff --git a/Documentation/scsi/ufs.txt b/Documentation/scsi/ufs.rst index 81842ec3e116..a920c0a5a1f6 100644 --- a/Documentation/scsi/ufs.txt +++ b/Documentation/scsi/ufs.rst @@ -1,24 +1,26 @@ - Universal Flash Storage - ======================= +.. SPDX-License-Identifier: GPL-2.0 +======================= +Universal Flash Storage +======================= -Contents --------- -1. Overview -2. UFS Architecture Overview - 2.1 Application Layer - 2.2 UFS Transport Protocol(UTP) layer - 2.3 UFS Interconnect(UIC) Layer -3. UFSHCD Overview - 3.1 UFS controller initialization - 3.2 UTP Transfer requests - 3.3 UFS error handling - 3.4 SCSI Error handling +.. Contents + + 1. Overview + 2. UFS Architecture Overview + 2.1 Application Layer + 2.2 UFS Transport Protocol(UTP) layer + 2.3 UFS Interconnect(UIC) Layer + 3. UFSHCD Overview + 3.1 UFS controller initialization + 3.2 UTP Transfer requests + 3.3 UFS error handling + 3.4 SCSI Error handling 1. Overview ------------ +=========== Universal Flash Storage(UFS) is a storage specification for flash devices. It is aimed to provide a universal storage interface for both @@ -28,19 +30,25 @@ is defined by JEDEC Solid State Technology Association. UFS is based on MIPI M-PHY physical layer standard. UFS uses MIPI M-PHY as the physical layer and MIPI Unipro as the link layer. -The main goals of UFS is to provide, +The main goals of UFS is to provide: + * Optimized performance: - For UFS version 1.0 and 1.1 the target performance is as follows, - Support for Gear1 is mandatory (rate A: 1248Mbps, rate B: 1457.6Mbps) - Support for Gear2 is optional (rate A: 2496Mbps, rate B: 2915.2Mbps) + + For UFS version 1.0 and 1.1 the target performance is as follows: + + - Support for Gear1 is mandatory (rate A: 1248Mbps, rate B: 1457.6Mbps) + - Support for Gear2 is optional (rate A: 2496Mbps, rate B: 2915.2Mbps) + Future version of the standard, - Gear3 (rate A: 4992Mbps, rate B: 5830.4Mbps) + + - Gear3 (rate A: 4992Mbps, rate B: 5830.4Mbps) + * Low power consumption * High random IOPs and low latency 2. UFS Architecture Overview ----------------------------- +============================ UFS has a layered communication architecture which is based on SCSI SAM-5 architectural model. @@ -48,16 +56,22 @@ SAM-5 architectural model. UFS communication architecture consists of following layers, 2.1 Application Layer +--------------------- The Application layer is composed of UFS command set layer(UCS), Task Manager and Device manager. The UFS interface is designed to be protocol agnostic, however SCSI has been selected as a baseline protocol for versions 1.0 and 1.1 of UFS protocol layer. + UFS supports subset of SCSI commands defined by SPC-4 and SBC-3. - * UCS: It handles SCSI commands supported by UFS specification. - * Task manager: It handles task management functions defined by the + + * UCS: + It handles SCSI commands supported by UFS specification. + * Task manager: + It handles task management functions defined by the UFS which are meant for command queue control. - * Device manager: It handles device level operations and device + * Device manager: + It handles device level operations and device configuration operations. Device level operations mainly involve device power management operations and commands to Interconnect layers. Device level configurations involve handling of query @@ -65,10 +79,12 @@ UFS communication architecture consists of following layers, information of the device. 2.2 UFS Transport Protocol(UTP) layer +------------------------------------- UTP layer provides services for the higher layers through Service Access Points. UTP defines 3 service access points for higher layers. + * UDM_SAP: Device manager service access point is exposed to device manager for device level operations. These device level operations are done through query requests. @@ -76,20 +92,23 @@ UFS communication architecture consists of following layers, set layer(UCS) to transport commands. * UTP_TM_SAP: Task management service access point is exposed to task manager to transport task management functions. + UTP transports messages through UFS protocol information unit(UPIU). 2.3 UFS Interconnect(UIC) Layer +------------------------------- UIC is the lowest layer of UFS layered architecture. It handles connection between UFS host and UFS device. UIC consists of MIPI UniPro and MIPI M-PHY. UIC provides 2 service access points to upper layer, + * UIC_SAP: To transport UPIU between UFS host and UFS device. * UIO_SAP: To issue commands to Unipro layers. 3. UFSHCD Overview ------------------- +================== The UFS host controller driver is based on Linux SCSI Framework. UFSHCD is a low level device driver which acts as an interface between @@ -98,12 +117,14 @@ SCSI Midlayer and PCIe based UFS host controllers. The current UFSHCD implementation supports following functionality, 3.1 UFS controller initialization +--------------------------------- The initialization module brings UFS host controller to active state and prepares the controller to transfer commands/response between UFSHCD and UFS device. 3.2 UTP Transfer requests +------------------------- Transfer request handling module of UFSHCD receives SCSI commands from SCSI Midlayer, forms UPIUs and issues the UPIUs to UFS Host @@ -112,11 +133,13 @@ The current UFSHCD implementation supports following functionality, of the status of the command. 3.3 UFS error handling +---------------------- Error handling module handles Host controller fatal errors, Device fatal errors and UIC interconnect layer related errors. 3.4 SCSI Error handling +----------------------- This is done through UFSHCD SCSI error handling routines registered with SCSI Midlayer. Examples of some of the error handling commands @@ -129,7 +152,7 @@ In this version of UFSHCD Query requests and power management functionality are not implemented. 4. BSG Support ------------------- +============== This transport driver supports exchanging UFS protocol information units (UPIUs) with a UFS device. Typically, user space will allocate @@ -138,7 +161,7 @@ request_upiu and reply_upiu respectively. Filling those UPIUs should be done in accordance with JEDEC spec UFS2.1 paragraph 10.7. *Caveat emptor*: The driver makes no further input validations and sends the UPIU to the device as it is. Open the bsg device in /dev/ufs-bsg and -send SG_IO with the applicable sg_io_v4: +send SG_IO with the applicable sg_io_v4:: io_hdr_v4.guard = 'Q'; io_hdr_v4.protocol = BSG_PROTOCOL_SCSI; @@ -166,6 +189,7 @@ upiu-based protocol is available at: For more detailed information about the tool and its supported features, please see the tool's README. -UFS Specifications can be found at, -UFS - http://www.jedec.org/sites/default/files/docs/JESD220.pdf -UFSHCI - http://www.jedec.org/sites/default/files/docs/JESD223.pdf +UFS Specifications can be found at: + +- UFS - http://www.jedec.org/sites/default/files/docs/JESD220.pdf +- UFSHCI - http://www.jedec.org/sites/default/files/docs/JESD223.pdf |