Network on a chip socket protocol

Patent metadata

Field	Value
Publication number	US-9225665-B2
Application number	US-201213626766-A
Country	US
Kind code	B2
Filing date	Sep 25, 2012
Priority date	Sep 25, 2012
Publication date	Dec 29, 2015
Grant date	Dec 29, 2015

Abstract

The invention is a transaction interface protocol wherein the interface protocol has a transaction identifier signal in each of the request and response channels. It is used between a target network interface unit (NIU) master and an initiator NIU slave that are directly connected through a transaction interface. The target NIU response channel uses the transaction ID signal to identify the entry in a context array associated with the corresponding request. The coupling of target NIU and initiator NIU enable the formation of an on-chip interconnect comprising multiple network-on-chip (NoCs) wherein the topology of the interconnect is simpler, smaller, faster, and has lower latency.

First claim

The invention claimed is:

1. A method of communicating between a first network-on-chip and a second network-on-chip, the method comprising:
receiving a request packet corresponding to a transaction, at a request transport interface of a target network interface unit (NIU) of the first network-on-chip, wherein the request packet is received at the request transport interface according to a transport layer protocol;
issuing a transaction request to an initiator NIU of the second network-on-chip via a socket interface request channel of the target NIU in response to receiving the request packet, wherein issuing the transaction request to the initiator NIU includes:
converting the request packet to the transaction request according to a transaction layer protocol;
asserting a value of a first transaction identifier signal on the socket interface request channel to the initiator NIU of the second network-on-chip, wherein the value of the first transaction identifier signal is unique to the transaction; and
allocating a context entry in a context array of the target NIU, wherein the context entry corresponds to the value of the first transaction identifier signal;

receiving a transaction response from the initiator NIU of the second network-on-chip at a socket interface response channel of the target NIU; and
retrieving the context entry from the context array based on a value of a second transaction identifier signal received at the socket interface response channel of the target NIU, wherein the value of the second transaction identifier signal is one of: the same as the value of the first transaction identifier signal and a transformation of the value of the first transaction identifier signal.

2. The method of claim 1 wherein the value of the first transaction identifier signal is associated with a packet header field of the request packet.

3. The method of claim 1 wherein a data width of the first and second transaction identifier signals and a presence of a number of protocol signals are configurable.

4. The method of claim 1 , wherein the value of the second transaction identifier signal forms an array index that points to the context entry in the context array of the target NIU.

5. The method of claim 1 , wherein the value of the first transaction identifier signal is mapped to an echo field of a packet header of the request packet.

6. A target network interface unit of a first network-on-chip, the target network interface comprising:
a request transport interface configured to receive a request packet, corresponding to a transaction, wherein the request packet is received at the request transport interface according to a transport layer protocol;
a socket interface request channel configured to convert the request packet to a transaction request according to a transaction layer protocol and to issue the transaction request to an initiator network interface unit of a second network-on-chip in response to the received request packet, and to assert a value of a first transaction identifier signal on the socket interface request channel to the initiator network interface unit of the second network-on-chip, wherein the value of the first transaction identifier signal is unique to the transaction;
a context array configured to store the value of the first transaction identifier signal in a context entry of the context array; and
a socket interface response channel configured to receive a transaction response from the initiator network interface unit of the second network-on-chip, wherein the target network interface unit is configured to retrieve the context entry from the context array based on a value of a second transaction identifier signal received at the socket interface response channel, wherein the value of the second transaction identifier signal is one of: the same as the value of the first transaction identifier signal and a transformation of the value of the first transaction identifier signal.

7. The target network interface unit of claim 6 wherein the value of the second transaction identifier signal forms an array index that points to the context entry in the context array.

8. The target network interface unit of claim 6 wherein the second transaction identifier signal has at least as many bits as a base two logarithm, rounded up, of a number of pending transactions.

9. The target network interface unit of claim 6 wherein at least one of pending transactions has a unique value of a respective transaction identifier signal.

10. The target network interface unit of claim 6 wherein the target network interface unit is configurable.

11. The target network interface unit of claim 6 wherein the target network interface unit is generated by a tool.

12. A system for on-chip interconnect, the system comprising:
an upstream network on chip comprising:
a target network interface unit; and
a context array within the target network interface unit; and

a downstream network on chip operably connected to the upstream network on chip, the downstream network on chip comprising an initiator network interface unit coupled to the target network interface unit of the upstream network on chip;
wherein the upstream network on chip is configured to:
receive a request packet, corresponding to a transaction, at a request transport interface of the target network interface unit of the upstream network on chip, wherein the request packet is received at the request transport interface according to a transport layer protocol;
issue a transaction request to the initiator network interface unit via a socket interface request channel of the target network interface unit in response to receiving the request packet, wherein issuing the transaction request to the initiator network interface unit includes:
converting the request packet to the transaction request according to a transaction layer protocol;
asserting a value of a first transaction identifier signal on the socket interface request channel to the initiator network interface unit of the downstream network on chip, wherein the value of the first transaction identifier signal is unique to the transaction; and
allocating a context entry in the context array of the target network interface unit, wherein the context entry corresponds to the value of the first transaction identifier signal;

receive a transaction response from the initiator network interface unit of the downstream network on chip at a socket interface response channel of the target network interface unit; and
retrieve the context entry from the context array based on a value of a second transaction identifier signal received at the socket interface response channel of the target network interface unit, wherein the value of the second transaction identifier signal is one of: the same as the value of the first transaction identifier signal and a transformation of the value of the first transaction identifier signal.

13. A method of designing chips comprising:
coupling a first network on chip with a second network on chip; and
generating an optimized protocol based on design requirements including a data size of one or more transaction identifier signals, wherein the optimized protocol allows the first network on chip to communicate with the second network on chip, wherein the first network on chip is configured to:
receive a request packet, corresponding to a transaction, at a request transport interface of a target network interface unit of the first network on chip, wherein the request packet is received at the request transport interface according to a transport layer protocol;
issue a transaction request to an initiator network

Assignees

• Qualcomm Technologies Inc

Inventors

• Boucard Philippe
• Lecler Jean-Jacques
• Boutillier Boris

Classifications

• G06F12/126

  with special data handling, e.g. priority of data or instructions, handling errors or pinning · CPC title

• G06F15/7825

  Globally asynchronous, locally synchronous, e.g. network on chip · CPC title

• H04L49/109 Primary

  Integrated on microchip, e.g. switch-on-chip · CPC title