MB86967 Datasheet, PDF (78/129 Pages) Fujitsu Component Limited. – LAN Controller with PC Card, ISA Bus, and General-purpose Bus Interfaces

MB86967
2. What’s in a Driver?
Typical node drivers manage the movement of packet data between system memory and the network, and vice
versa, as well as providing diagnostic testing, error processing, and error statistics on-demand for the system.
The first thing a driver does when the system is powered up is system check-out, which may include buffer
memory testing, and loopback testing of the transmit and receive circuits. If the network supports it, as does
Ethernet, for example, the testing may include sending and receiving test packets on the network to verify the
ability to communicate.
As shown in Figure 10, the driver provides control of the initialization, interrupt and branch control processes,
supporting both the transmit and the receive functions.
Start
Interrupt
Initialization
Interrupt
Service
Request
Receive
Read
Branch
Control
Newtwork
Software
Transmit
Request
Transmit
Write
Exit
Exit
Exit
Figure 10 Software Driver Model
Figure 11 shows an example in flow chart form of a check-out routine written for the Fujitsu MB86967 Controller.
The driver first initializes the control and status registers in the controller for memory and loopback testing.
Loopback and memory testing are conducted simultaneously by transmitting memory test patterns from the
transmit buffer area of memory to the receive buffer area using loopback. This test sequence simultaneously
exercises and tests the transmitter, the receiver and the buffer memory.
The loopback/memory startup test is performed by first loading a test pattern in the form of several packets into
the controller chip’s transmit buffer, then transmitting the packets in loopback mode. The loopback transmission
path through the chip exercises the data link controller as well as the encoder and decoder circuitry, but does
not affect the network.
The MB86967 controller has a unique buffer memory architecture which pipelines packets through the system
in both directions, optimizing data through-put. MB86967’s buffer controller provides all the pointer management
for accessing the buffer automatically, greatly reducing the complexity of the driver and minimizing the software
overhead. Receive packets with errors are automatically purged by MB86967. When a collision occurs, MB86967
automatically re-transmits without host interaction. These features provide high data throughput while minimizing
the host and memory overhead. At the successful conclusion of the tests, the driver starts up the MB86967 chip
for regular service on the network.
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