1.1.8.1 How the SFDP Library Works

The SFDP driver library is a single-client, single-instance based driver interface.

Abstraction Model

The SFDP driver interface provides read, write and Erase functions that abstract out the internal workings of the SFDP driver and the underlying QSPI/SQI/SPI protocol.

The client can be:

• Application - Directly access the JEDEC-Compliant NOR Flash using the APIs provided by the SFDP Driver library
• Memory Driver - Application can run a file system on the SFDP Flash by connecting it to the Memory Driver which can further be connected to the File System Service

Working Flow

• The SFDP Driver performs initialization and puts the driver to ready state. This status of the driver can be checked using DRV_SFDP_Status().
• The SFDP driver library performs a set of Flash operations during DRV_SFDP_Open() including SFDP discovery. If any of the below Flash operations fails, an invalid Handle will be returned. DRV_SFDP_Open() can be repeatedly called until it returns a valid handle.
  • Resets the Flash Device
  • Discovers Flash parameters using SFDP (JESD216)
  • Configures the Flash device to QUAD IO mode if supported
  • Unlocks the Flash if it has been opened in write mode
• When the client requests for device geometry, it uses the SFDP-discovered parameters to populate the geometry table DRV_SFDP_GEOMETRY appropriately.
• The driver does not support queuing of more than one request. The application must check and ensure that any previous request is completed before submitting a new one. This can be done by polling the status of data transfer using DRV_SFDP_TransferStatusGet().