Motorola MPC5200 Manuel D’Utilisation

The 

KwikNet

 MPC5200 FEC device driver must initialize the BestComm FEC receive and

transmit tasks to match the driver's configured requirements.  Unfortunately, the
BestComm FEC initialization must only be performed once.  However, the MPC5200
FEC driver can be opened and closed many times as 

KwikNet

 operates.  Each time the

driver is opened, it must initialize the FEC hardware but it must only initialize the
BestComm FEC subsystem once.

To meet this requirement, an FEC initialization procedure 

 is

provided in source file 

.  The 

d

evice driver calls this procedure to prepare the

BestComm FEC subsystem for subsequent use by the driver.  The procedure is called
every time that the Ethernet network interface is opened for use.

The function receives a pointer to an initialization structure 

 defined in

header file 

.  This structure serves two purposes.  On input, it presents the

configuration information needed to initialize the BestComm FEC subsystem.  On output,
it contains the task identifiers for the BestComm FEC RX and TX tasks.

Procedure 

 maintains a copy of structure 

 as

received the first time that the function is called.  The BestComm FEC subsystem is
initialized and the results are saved in static variable 

.  On subsequent calls to

, the input parameters are compared to the saved values.  If the new

parameters do not match the original values, the call is rejected with an error status
because the BestComm FEC subsystem cannot be reconfigured to meet the revised
configuration requested.

A custom timing service is implemented in source file 

 for the benefit of the

MPC5200 FEC device driver.  Precise timing is derived from the internal MPC5200
Time Base Register.  Procedure 

 can be used to instrument a compute

bound delay with microsecond precision.  This procedure supercedes the crude delay
function offered by 

KwikNet

 procedure 

.  Note that proper operation of

procedure 

 depends upon the time base clock frequency as defined by

symbol 

 in header file 

.

You are free to edit source file 

 to adapt the BestComm FEC initialization

sequence to your particular needs.  Alternatively, you can merge the code from module

 into your own BestComm task initialization module, being sure to retain

FEC setup procedure 

 and its functional integrity.

Two low level MPC5200 register access functions are provided in source file

.  Function 

 reads the Memory Base Address Register (

)

and returns its value to the caller.  Function 

 reads the low order 32 bits of

the 64-bit Time Base Register (TB) and returns its value to the caller.

These functions are implemented using the assembly language features offered by each of
the C compilers tested by KADAK.  The functions are implemented in a compiler
specific manner in header file 

.  Instances of the functions are included near

the end of source file 

 by defining symbol 

 and

including header file 

 for a second time.