Method To Support Flexible Data Transport On Serial Protocols

• US 20090225769A1
• Filed: 03/06/2008
• Published: 09/10/2009
• Est. Priority Date: 03/06/2008
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: Wang, Chi-Lie, Mo, Jason Z.
• Granted Patent: US 8,625,621 B2
• Time in Patent Office: Days
• US Class Current: 370/412
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/9042 Separate storage for different parts of the packet, e.g. header and payload

Abstract

A serial buffer transports packets through queues capable of operating in a packet mode or a raw data mode. In packet mode, entire packets are stored in a queue. In raw data mode, packet header/delimiter information is not stored in the queue (only packet data is stored). Packets can be transferred out of a queue in response to a slave read request. The serial buffer constructs a packet header in response to the slave read request, and retrieves a specified amount of packet data from the selected queue. The serial buffer also transfers out packets as a bus master when a water level exceeds a water mark within a queue. The serial buffer constructs packet headers for these bus master transfers, which may be performed in a flush mode or a non-flush mode (in packet mode), or in a flush mode (in raw data mode).

Claims

1. A serial buffer comprising:

one or more queues;

means for configuring each of the one or more queues to operate in either a packet mode or a raw data mode; and

write control logic configured to write both a packet header and corresponding packet data to queues configured to operate in the packet mode, and configured to write only packet data to queues configured to operate in the raw data mode.

2. The serial buffer of claim 1, further comprising:

a first port configured to operate in accordance with a first serial protocol; and

a second port configured to operate in accordance with a second serial protocol, different than the first serial protocol, wherein the first port and the second port are coupled to the write control logic.

3. The serial buffer of claim 1, further comprising read control logic configured to read packet data from a queue in response to a slave read request.

4. The serial buffer of claim 3, wherein the slave read request includes a data size field that specifies a size of the packet data to be read from the queue.

5. The serial buffer of claim 1, further comprising read control logic configured to read packet data from a queue as a bus master in response to determining that a water level of the queue exceeds a water mark of the queue.

6. The serial buffer of claim 5, further comprising means for configuring the queue in a flush mode, which causes the read control logic to read all packet data below the water mark of the queue.

7. The serial buffer of claim 6, further comprising means for configuring the queue in a non-flush mode, which causes the read control logic to read packet data associated with a single packet from the queue.

8. The serial buffer of claim 1, further comprising read control logic configured to read packet data from a queue configured to operate in the raw data mode, wherein the read control logic is further configured to construct a packet header, which is appended to the packet data read from the queue.

9. The serial buffer of claim 8, wherein the read control logic is configured to construct the packet header in response to a slave read request packet.

10. The serial buffer of claim 9, wherein the read control logic is configured to read multiple packets in packet mode or multiple data values in raw data mode in response to a specified read size value included in the slave read request packet.

11. The serial buffer of claim 8, wherein the read control logic is configured to construct the packet header in response to an identity of the queue.

12. A method of operating a serial buffer comprising:

configuring a first queue to operate in a packet mode;

configuring a second queue to operate in a raw data mode;

receiving an incoming packet that includes a packet header and packet data;

determining whether the incoming packet specifies the first queue or the second queue;

writing the packet header and packet data of the incoming packet to the first queue if the incoming packet specifies the first queue; and

writing the packet data, but not the packet header, of the incoming packet to the second queue if the incoming packet specifies the second queue.

13. The method of claim 12, wherein packet data written to the second queue includes start-of-packet and end-of-packet delimiters.

14. The method of claim 12, further comprising:

determining when a water level of the first queue reaches a water mark assigned to the first queue; and

reading all packet headers and packet data below the water mark assigned to the first queue upon determining that the water level of the first queue has reached the water mark assigned to the first queue.

15. The method of claim 14, further comprising:

configuring a third queue to operate in the packet mode;

determining whether the incoming packet specifies the third queue;

writing the packet header and packet data of the incoming packet to the third queue if the incoming packet specifies the third queue;

determining when a water level of the third queue reaches a water mark assigned to the third queue; and

reading all packet headers and packet data below the water mark assigned to the third queue upon determining that the water level of the third queue has reached the water mark assigned to the third queue, wherein the water mark assigned to the third queue is different than the water mark assigned to the first queue.

16. The method of claim 15, wherein the incoming packet represents a first amount of data, and the water mark assigned to the first queue represents a second amount of data, wherein the first amount of data is different than the second amount of data.

17. The method of claim 12, further comprising:

determining when a water level of the second queue reaches a water mark assigned to the second queue; and

reading all packet data below the water mark assigned to the second queue in response to determining that the water level of the second queue has reached the water mark assigned to the second queue.

18. The method of claim 17, wherein the packet data written to the second queue has a first size, and the packet data below the water mark assigned to the second queue has a second size, different than the first size.

19. The method of claim 18, wherein the second size is greater than the first size.

20. The method of claim 18, wherein the second size is less than the first size.

21. The method of claim 12, further comprising:

receiving a first slave read request packet from a first processor; and

transferring packet data from the second queue to the first processor in response to the first slave read request packet, wherein the first slave read request packet specifies a first amount of data read from the second queue.

22. The method of claim 21, further comprising:

receiving a second slave read request packet from a second processor; and

transferring packet data from the second queue to the second processor in response to the second slave read request packet, wherein the second slave read request packet specifies a second amount of data read from the second queue.

23. The method of claim 22, wherein the first amount of data is different than the first amount of data.

24. The method of claim 21, wherein the first amount of data read from the second queue is different than an amount of packet data written to the second queue during a write operation to the second queue.