Intel IXP400 15.5.2 Sending an NPE Message with Response

Intel® IXP400 Software
Access-Layer Components: NPE Message Handler (IxNpeMh) API
April 2005 IXP400 Software Version 2.0 Programmer’s Guide
228 Document Number: 252539, Revision: 007
15.5.2 Sending an NPE Message with Response
In this case, the client’s message requires a response from the NPE. The scenario (as shown in
Figure 72) is:
1. The client sends a message to the IxNpeMh component, specifying the destination NPE and a
response callback.
2. The IxNpeMh component checks that the NPE can accept a message.
If the component cannot accept a message, the send fails.
3. The IxNpeMh component adds the response callback to the end of the solicited callback list
and sends the message to the NPE.
4. After some time, the NPEs “outFIFO not empty” interrupt invokes the IxNpeMh component’s
ISR.
5. Within the ISR, the IxNpeMh component receives a message from the specific NPE.
6. The IxNpeMh component checks if this message ID has an unsolicited callback registered for
it.
If the messages has an unsolicited callback registered, the message is unsolicited. (See
“Receiving Unsolicited Messages from an NPE to Client Software” on page 229.)
Figure 71. Message from Intel XScale® Core Software Client to an NPE
Client
IxNpeMh
NPE B NPE CNPE A
Customer / Demo Code
Access Driver
NPEs
1. Send Message
callback n+k
...
callback n+1
callback n
0x00 callback
0x01 callback
...
0xff callback
2. Send Message
B2395-01