Motorola MPC5200 用户手册

By default, the MPC5200 FEC device driver is configured to use a third, preferred
method of operation.  The driver uses a 

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 timer to periodically sample the PHY,

watching for the auto-negotiation to complete.  The sampling period, the wait interval
and an additional post-negotiation delay are all configurable parameters.  By default, the
driver samples at the 

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 clock frequency for up to 3 seconds, with no additional

delay.

The device driver reports the success or failure of the auto-negotiation process to the
Ethernet network driver.  If a link has been established, the network driver completes the
opening process and declares the network interface operational.  If necessary, IP address
negotiation will then be initiated using either DHCP or AutoIP according to your network
interface definition.

If the PHY auto-negotiation fails, the Ethernet network driver will declare that the
network interface cannot be opened for use.

To alter the MPC5200 FEC device driver's PHY initialization strategy, you must edit the
device driver header file 

.  Define symbol 

 to be 

 for no

delay, 

 for continuous polling and 

 (the default) for periodic

sampling.  The timeout interval(s) and sampling interval can be defined as described in
the file.

When the periodic sampling method is used (

 is 

), the device

driver generates a network event to signal the success (

) or failure

(

) of the PHY auto negotiation.

If you implement the 

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 event notification function 

 as described in

Chapter 4.5 of the 

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 TCP/IP Stack User's Guide, your function will be called

whenever either of these network events is generated.  Note that your function will be
called again when the network is subsequently declared open (up) or closed (down).