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diff --git a/Documentation/scsi/ufs.txt b/Documentation/scsi/ufs.txt deleted file mode 100644 index 81842ec3e116..000000000000 --- a/Documentation/scsi/ufs.txt +++ /dev/null @@ -1,171 +0,0 @@ - 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 - - -1. Overview ------------ - -Universal Flash Storage(UFS) is a storage specification for flash devices. -It is aimed to provide a universal storage interface for both -embedded and removable flash memory based storage in mobile -devices such as smart phones and tablet computers. The specification -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, - * 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) - Future version of the standard, - 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. - -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 - UFS which are meant for command queue control. - * 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 - requests which are used to modify and retrieve configuration - 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. - * UTP_CMD_SAP: Command service access point is exposed to UFS command - 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 -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 - controller. Also, the module decodes, responses received from UFS - host controller in the form of UPIUs and intimates the SCSI Midlayer - 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 - issues by SCSI Midlayer are Abort task, Lun reset and host reset. - UFSHCD Routines to perform these tasks are registered with - SCSI Midlayer through .eh_abort_handler, .eh_device_reset_handler and - .eh_host_reset_handler. - -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 -struct ufs_bsg_request and struct ufs_bsg_reply (see ufs_bsg.h) as -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: - - io_hdr_v4.guard = 'Q'; - io_hdr_v4.protocol = BSG_PROTOCOL_SCSI; - io_hdr_v4.subprotocol = BSG_SUB_PROTOCOL_SCSI_TRANSPORT; - io_hdr_v4.response = (__u64)reply_upiu; - io_hdr_v4.max_response_len = reply_len; - io_hdr_v4.request_len = request_len; - io_hdr_v4.request = (__u64)request_upiu; - if (dir == SG_DXFER_TO_DEV) { - io_hdr_v4.dout_xfer_len = (uint32_t)byte_cnt; - io_hdr_v4.dout_xferp = (uintptr_t)(__u64)buff; - } else { - io_hdr_v4.din_xfer_len = (uint32_t)byte_cnt; - io_hdr_v4.din_xferp = (uintptr_t)(__u64)buff; - } - -If you wish to read or write a descriptor, use the appropriate xferp of -sg_io_v4. - -The userspace tool that interacts with the ufs-bsg endpoint and uses its -upiu-based protocol is available at: - - https://github.com/westerndigitalcorporation/ufs-tool - -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 |