here's an excerpt from the Digi Embedded Linux Documentation:
9.16. Flexible Interface Modules (FIMs)
The NS9210 and NS9215 processors have two I/O processors, called flexible interface modules (FIMs), to implement simple communication protocols and other functions. These processors can be used to implement various I/O functions. The PIC processors communicate with the ARM9 via interrupts and status registers, and with the system memory via transmit and receive FIFOs. Both PICs are optimized with generic I/O hardware assist for parallel bus applications and specialized hardware assist for CAN protocol applications.
Three main steps are required to use a FIM:
1. Write a firmware program into the FIM memory.
2. Select the hardware assistance mode (if the generic hardware assistance mode is selected, then the signals and buses for it must also be configured).
3. Start the FIM.
9.16.1. Supported device drivers
Currently, these drivers are supported for the FIMs:
* UART interface: The firmware implements a 4-wire UART, for getting an extra serial port
* SDIO-Host interface: The firmware implements an SDIO host controller for managing any SD and SDIO-capable card.
* CAN bus: The firmware implements a CAN controller.
To use these interfaces additional hardware is needed to provide a physical layer for the UART, an SD socket, and a CAN port. The connector on the development board only provides the FIMs' data and control lines.
Drivers are included in DEL 5.0
Hope this helps,