Interrupt Type Codes
4-9
Interrupt Handling
4.4.6
Tx EOC Interrupt. Int_type = 101b
A Tx EOC interrupt occurs when ThunderLAN encounters a forward pointer
of 0 in the Tx list structure or when the Ld_Thr bit is loaded with 0. In this routine
the driver:
-
Gets the pointer to the Tx buffer queue
-
Checks the list CSTAT to see if a frame has been transmitted
J
If no, acknowledges the interrupt and exits
J
If yes, writes a 0 to CSTAT to make the list invalid
4.4.7
Network Status Interrupt. Int_type = 110b and Int_Vec = 00h
A network status interrupt occurs when a PHY status change has been de-
tected and ThunderLAN has seen an interrupt on the MDIO line. This interrupt
type occurs only if a physical interface (PHY) with enhanced media indepen-
dent interface (MII) support is used.
Some other causes of a status interrupt occur when the Tx and Rx channels
are stopped using a STOP command. The following shows the flow for a status
interrupt routine:
-
Reads the NetSts
register
-
Clears the NetSts register. NetSts
can be easily cleared by writing what
has been read back into it.
-
Reads the NetMask
register
-
Uses NetMask to ignore the NetSts bits, which are disabled
-
Evaluates the following conditions:
J
If the MIRQ bit is set, there was an MII interrupt from the PHY. For
voice grade (VG) operation, this is an indication that the PHY needs to
retrain.
J
If the HBEAT bit is set, a heartbeat error was detected.
J
If the TXSTOP bit is set, a Tx STOP command was given and the Tx
channel is stopped.
J
If the RXSTOP bit is set, an Rx STOP command was given and the Rx
channel is stopped.
-
Acknowledges interrupts and exits
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