Packet, Srio functional description – Texas Instruments TMS320C645X User Manual
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Mailbox 1...64
from RapidIO Packet
Header - Received on any
input port
Mailbox Mapper
Q15
Q2
Q1
Q0
Queue assignable to any core
Packet Sequence
Message
n
A
Packet
Manager
n+1
B
n+2
B
n+3
C
n+4
D
n+5
B
n+6
E
Buffer Descriptor
Queues:
Descriptor per Message
All Priorities
Dedicated Single Segment
Message Descriptor Queue
A
C
E
D
null
null
B
Multi-Segment Message
Descriptor Queue
Multi-Segment Message
Descriptor Queue N
L2 Memory
Data Buffer up to 256B
n Data Packet
n+3 Data Packet
n+4 Data Packet
n+6 Data Packet
256B Free Buffer
L2 Memory
Data Buffer up to 4K
n+5 Data Packet
n+2 Data Packet
n+1 Data Packet
4KB Free Buffer
acklD
rsv
prio
tt
ftype
ftype = 1011
destID sourcelD msglen
ssize
msgseg/xmbox double-word 0 double-word 1
...
double-word n-2
double-word n-1
CRC
PHY
LOG
TRA
LOG
TRA
PHY
5
3
2
2
4
8
8
4
4
4
64
64
(n-4)*64
64
64
16
16
n*64+16
16
4
2
10
n*64+64
letter
2
mbox
2
SRIO Functional Description
2.3.4.1
RX Operation
As message packets are received by the RapidIO ports, the data must be written into memory while
maintaining accurate state information that is needed for future processing. For instance, if a message
spans multiple packets, information must be saved that allows re-assembly of those packets by the CPU.
The CPPI module provides a scheme for tracking single and multi-packet messages, linking messages in
queues, and generating interrupts.
illustrates the scheme.
Figure 14. CPPI RX Scheme for RapidIO
Messages addressed to any of the 64 mailbox locations can be received on any of the RapidIO ports
simultaneously. Packets are handled sequentially in order of receipt. The function of the mailbox mapper
block is to direct the inbound messages to the appropriate queue and finally to the correct core. The
queue mapping is programmable and must be configured after device reset. RapidIO originally supported
only 4 mailboxes with 4 letters/mailbox. Letters allow concurrent message traffic between sender and
receiver. However, for messages that consist of only single packets, the unused 4-bit packet field normally
indicating the message segment extends the available number of mailboxes.
shows the packet
header fields for message requests.
Figure 15. Message Request Packet
SPRU976 – March 2006
Serial RapidIO (SRIO)
41