Auto-polling unit for interrupt generation in a network interface device

• US 6,065,073 A
• Filed: 08/17/1998
• Issued: 05/16/2000
• Est. Priority Date: 08/17/1998
• Status: Expired due to Term

• Current Assignee: Jato Technologies, Inc. (Intel Corporation)
• Original Assignee: Jato Technologies, Inc. (Intel Corporation)
• Inventors: Booth, Bradley J.
• Primary Examiner(s): Ray, Gopal C.
• Application Number:
  US09/135,340
• Time in Patent Office: 638 Days
• Field of Search: 709/203, 709/218, 709/250, 709/252, 709/253, 709/223, 710/8, 710/15, 710/18, 710/46, 710/47, 710/129, 710/220, 710/266, 710/267, 714/47, 714/4, 714/48, 714/25, 714/819, 713/100, 359/109, 359/118, 370/908, 370/901, 370/906, 340/825.06, 455/9
• US Class Current: 710/46
• CPC Class Codes: G06F 13/24 using interrupt G06F13/32 takes precedence
• CPC Class Codes: H04L 12/40032 Details regarding a bus interface enhancer
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: Y10S 370/908 Local area network

Abstract

A system and method for auto-polling a status register within a physical layer (PHY) interface to a local area network (LAN). The system includes a host CPU which needs to detect and service interrupts generated by a PHY device on the LAN which is coupled between a first transmission medium (such as copper or fiber cable) and a management interface to the system. The system further includes an auto-polling unit which monitors activity on the management interface of the PHY device. When the auto-polling unit detects a lack of activity on the management interface of the PHY for a predetermined interval, the auto-polling unit reads a first value from the PHY status register. This first status value is then compared to a previously stored value which corresponds to the last PHY status value read by the host CPU. If a mismatch is detected between these two values, an interrupt is generated to the CPU. In response to receiving the interrupt, auto-polling is suspended (to avoid changing the status data that caused the interrupt) and the CPU requests a read of the status value in the first register. In this manner, the CPU is able to access the status value which caused the interrupt and determine the appropriate course of action. This status read by the CPU also has the effect of clearing the interrupt. This system frees the CPU from having to continually poll the PHY status register to determine if a change in status has occurred.

Claims

1. A computer system, comprising:

a host CPU;

an IO interface device coupled to said computer system via a management interface;

an auto-polling unit configured to monitor activity on said management interface, wherein said auto-polling unit is configured to read a first status value from a status register within said 10 interface device in response to detecting a lack of activity on said management interface over a predetermined interval;

wherein said auto-polling unit is further configured to compare said first status value to a second status value, wherein said second status value is a most recent status value read by said host CPU from said status register;

wherein said auto-polling unit is configured to generate an interrupt to said host CPU in response to detecting a mismatch between said first status value and said second status value.

2. The computer system of claim 1, wherein said auto-polling unit includes a host CPU data register configured to store said most recent status value read by said host CPU from said status register, wherein said host CPU data register is configured to store said second status value.

3. The computer system of claim 2, wherein said auto-polling unit includes an auto-poll data register configured to store a most recent status value read by said auto-polling unit from said status register, wherein said auto-poll data register is configured to store said first status value.

4. The computer system of claim 3, wherein said auto-polling unit includes a comparator coupled to receive current values from said host CPU data register and said auto-poll data register, wherein said comparator is configured to perform a comparison between said current values from said host CPU data register and said auto-poll data register, wherein said comparator is configured to generate said interrupt in response to detecting a mismatch between said current values from said host CPU data register and said auto-poll data register.

5. The computer system of claim 1, wherein said host CPU is configured to perform a request for a read of said status register in response to receiving said interrupt, wherein said auto-polling unit is configured to convey said first status value to said host CPU in response to said request.

6. The computer system of claim 5, wherein said auto-polling unit is configured to clear said interrupt in response to said host CPU performing said request.

7. The computer system of claim 1, wherein said predetermined interval is variable.

8. The computer system of claim 7, wherein said predetermined interval is set by said host CPU.

9. The computer system of claim 1, wherein said auto-polling unit monitoring activity on said management interface is suspended while said interrupt is asserted.

10. The computer system of claim 1, wherein said management interface is usable to set control values within said IO interface device, wherein said control values govern operation of said IO interface device.

11. A computer system, comprising:

a host CPU;

a network interface device coupled between a first transmission medium and a management interface to said computer system;

an auto-polling unit configured to monitor activity on said management interface of said network interface device, wherein said auto-polling unit is configured to read a first status value from a status register within said network interface device in response to detecting a lack of activity on said management interface over a predetermined interval;

wherein said auto-polling unit is further configured to compare said first status value to a second status value, wherein said second status value is a most recent status value read by said host CPU from said status register;

wherein said auto-polling unit is configured to generate an interrupt to said host CPU in response to detecting a mismatch between said first status value and said second status value.

12. The computer system of claim 11, wherein said interrupt is indicative of an interrupt condition in a first communications channel which includes said network interface device and said first transmission medium.

13. The computer system of claim 12, wherein said status register includes indications of conditions selected from the group consisting of:

(i) state of auto-negotiation state machine, (ii) a remote fault generated in auto-negotiation capable PHY devices, (iii) link status, and (iv) jabber detection.

14. The computer system of claim 11, wherein said network interface device is a physical layer interface (PHY) device.

15. The computer system of claim 14, wherein said status register is a PHY status register.

16. The computer system of claim 11, wherein said first transmission medium is selected from the group consisting of:

(i) fiber-optic cable, (ii) unshielded twisted-pair (UTP) cable and (iii) coaxial cable.

17. The computer system of claim 11, wherein said management interface includes a clock signal and a serial data signal.

18. The computer system of claim 17, wherein said lack of activity on said management interface is detected by said auto-polling unit detecting no data transfers on said serial data signal for a predetermined number of cycles on said clock signal.

19. The computer system of claim 11, wherein said management interface is usable to set control values within said network interface device, wherein said control values govern operation of said network interface device.

20. The computer system of claim 11, wherein said auto-polling unit includes a host CPU data register configured to store said most recent status value read by said host CPU from said status register.

21. The computer system of claim 20, wherein said auto-polling unit includes a first auto-polling data register configured to store a most recent status value read by said auto-polling unit from said status register.

22. The computer system of claim 21, wherein said auto-polling unit includes a second auto-polling data register also configured to store said most recent status value read by said auto-polling unit from said status register.

23. The computer system of claim 22, wherein said auto-polling unit further includes a comparator coupled to receive current values from said host CPU data register and said first auto-polling data register, wherein said comparator is configured to assert said interrupt in response to detecting a mismatch between said current values.

24. The computer system of claim 23, wherein said host CPU is configured to perform a request for said first status value in response to receiving said interrupt.

25. The computer system of claim 24, wherein said request for said first status value also operates to cause said host CPU data register and said first auto-polling data register to update to a common value.

26. The computer system of claim 25, wherein said host CPU data register and said first auto-polling data register updating to said common value operates to clear said interrupt.

27. The computer system of claim 23 wherein said auto-polling unit is configured to supply said first status value from said second auto-polling data register in response to receiving said request for said first status value from said host CPU.

28. The computer system of claim 11, further comprising a network interface card, wherein said network interface card includes said network interface device and said auto-polling unit.

29. The computer system of claim 28, wherein said auto-polling unit is included in a LAN controller unit within said network interface card.

30. The computer system of claim 29, further comprising an IO controller coupled between said host CPU and said network interface card.

31. The computer system of claim 11, wherein said auto-polling unit is configured to continue monitoring activity on said management interface of said network interface device in response to said first status value being equal to said second status value.

32. The computer system of claim 11, wherein said status register is a first status register of a plurality of status registers within said network interface device, and wherein said host CPU is configured to determine which of said plurality of status registers is to be read for interrupt determination.

33. A method for generating an interrupt in a computer system which includes a host CPU, an IO interface device, and an auto-polling unit, said method comprising:

said auto-polling unit monitoring activity on a management interface coupled to said IO interface device;

said auto-polling unit detecting a lack of activity on said management interface over a predetermined interval;

said auto-polling unit reading a first status value from a status register within said IO interface device;

said auto-polling unit comparing said first status value to a second status value, wherein said second status value is a most recent status value read by said host CPU from said status register;

said auto-polling unit generating said interrupt to said host CPU in response to detecting a mismatch between said first status value and said second status value.

34. The method of claim 33, further comprising continuing said monitoring in response to detecting a match between said first status value and said second status value.

35. The method of claim 33, further comprising said host CPU requesting a read of said status register in response to receiving said interrupt.

36. The method of claim 35, further comprising said auto-polling unit returning said first status value in response to said host CPU requesting said read of said status register.

37. The method of claim 36, further comprising clearing said interrupt in response to said host CPU requesting said read of said status register.

38. A computer system configured to perform auto-polling of a network interface device, comprising:

a host CPU;

an auto-polling unit;

a network interface device;

wherein said host CPU is configured to enable said auto-polling unit to perform auto-polling of said network interface device;

wherein said auto-polling unit is configured to poll said network interface in response to detecting a lack of activity on a management interface of said network interface device, and wherein said auto-polling unit is configured to signal an interrupt to said host CPU in response to detecting a status value which indicates an interrupt condition;

and wherein said host CPU is configured to read said status value which caused said interrupt condition;

and wherein said host CPU is configured to de-assert said interrupt in response to reading said status value.