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fuchsia/fuchsia/ce365daea8f24d2d7d66688e5b3f3745b1aaabf7/./src/devices/block/drivers/ufs
tree: 57eeae0a6d26b1dbd97839da0f7739f3a9af8655
  1. meta/
  2. test/
  3. uic/
  4. upiu/
  5. bind_tests.json
  6. BUILD.gn
  7. logical_unit.cc
  8. logical_unit.h
  9. README.md
  10. registers.h
  11. request_list.cc
  12. request_list.h
  13. request_processor.h
  14. transfer_request_descriptor.h
  15. transfer_request_processor.cc
  16. transfer_request_processor.h
  17. ufs-info.json
  18. ufs.bind
  19. ufs.cc
  20. ufs.h
src/devices/block/drivers/ufs/README.md

Universal Flash Storage (UFS)

Universal Flash Storage (UFS) is a flash-based mobile storage device that provides high performance, low power, and high reliability compared to eMMC. Unlike eMMC, which uses a parallel bus, UFS uses a high-speed, multi-lane serial bus to improve performance. The serial interface of UFS uses LVDS differential signaling, which enables high-speed signal transmission with high noise immunity and low voltage. UFS follows the UFS specification of the JEDEC standard, which is currently up to version 4.0. Fuchsia's UFS driver is based on the UFS specification version 3.1.

Specification

UFS: https://www.jedec.org/document_search?search_api_views_fulltext=jesd220f UFSHCI: https://www.jedec.org/standards-documents/docs/jesd223e

Layered Architecture

The layered architecture of UFS uses the M-PHY physical layer and the UniPro link layer, with the UFS Transfer Protocol (UTP) transport layer on top. It also adopts a SCSI architecture model and command protocol that supports multiple simultaneous commands and command queues on top of the UTP transport layer. The layered architecture of UFS consists of three layers: UFS Application Layer(UAP), UFS Transport Protocol Layer (UTP), and UFS InterConnect Layer (UIC). The UFS driver is implemented according to this layered architecture.

UFS Application Layer (UAP)

The UAP layer consists of the UFS Command Set Layer (UCS), Device Manager, and Task Manager.

  • The UFS Command Set Layer processes SCSI commands.
  • Device Manager is responsible for device settings such as data transfer and power mode control, and controls them through descriptor, attribute, and flag requests.
  • Task Manager is responsible for processing the task management function for command queue control.

UFS Transport Protocol Layer (UTP)

UTP layer uses UFS Protocol Information Unit (UPIU) for message delivery between UAP layer and UFS Interconnect (UIC) layer. The UTP layer wraps information from the UAP layer in a UPIU and delivers it to the UFS device.

UFS InterConnect Layer (UIC)

The lowest layer, the UIC layer, handles the connection between the UFS host interface and the UFS device. The UIC layer automatically detects and recovers I/O errors through the UniPro link layer, and provides reliable data transfer through the M-PHY physical layer.

TODO

  • Refactoring I/O queue
  • Support large size I/O
  • Support FLUSH command
  • Support FUA flag
  • Support TRIM command (unmap)
  • Support write booster
  • Support Power Mode
  • Support RPMB logical unit
  • Support well-known LU
  • Support Utp Task Management Request
  • Implement Ufs tools
  • Integration tests
  • Support high speed gear 2
  • Support UFS 4.0 Spec (multi queue)
  • Support multiple platform (exynos, snapdragon, etc.)

How to test

Ufs driver unit tests (not yet ready)

  • Build configuration for ufs tests

$ fx set core.x64 --with //src/devices/block/drivers/ufs:tests

  • Run ufs unit tests

$ fx test ufs-unit-tests

Test on real device

Currently, the only device that supports a PCI-based UFS host controller is the Samsung Galaxy Book S(NT767XCL) with an Intel Lakefield CPU(i5-L16G7). The Galaxy Book S has 512GB of eUFS 3.0 storage. Unfortunately, we can‘t run Fuchsia OS on that laptop yet, but we’ll find a way.