Input/output bus architecture with parallel arbitration

• US 5,459,840 A
• Filed: 02/26/1993
• Issued: 10/17/1995
• Est. Priority Date: 02/26/1993
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Strohl, Niles E., Isfeld, Mark S., Bowman, Michael H.
• Primary Examiner(s): Harvey, Jack B.
• Assistant Examiner(s): AUVE, GLENN ALLEN
• Application Number:
  US08/023,008
• Time in Patent Office: 963 Days
• Field of Search: 395/325, 395/275, 395/725, 395/425
• US Class Current: 710/240
• CPC Class Codes: G06F 13/374 using a self-select method with individual priority code comparator

Abstract

A high performance bus suitable for high speed internetworking applications which is based on three bus phase types, including an arbitration phase, an address phase, and a data phase. The arbitration, address, and data phases share a single set of lines. Distributed arbitration logic on each of the interface devices supplies local arbitration codes to a particular line in the set of lines in the arbitration cycle, and detects an arbitration win during the same phase in response to the local arbitration code, and other arbitration codes driven on the set of lines during the arbitration cycle. Each module coupled to the bus also assigned a local priority code. During the arbitration cycle, both the arbitration code and the priority code are driven on respective subsets of the shared sets of lines. Assertion of the local priority code overrides normal requests for the bus. The arbitration logic on each module includes a bus request logic which has the effect of defining arbitration cycles, such that in a particular arbitration phase, a group of modules that asserts a bus request signal controls the bus request signal until all modules in the group have won arbitration.

Claims

1. A bus interface for connection of a local data processing module to a tri-state bus, comprising:

control means, coupled to the bus and the local data processing module, for detecting bus phases;

arbitration logic, coupled to a set of arbitration lines of the bus and responsive to the control means, including means for supplying a local arbitration code to a first designated subset of the set of arbitration lines and tri-stating other lines in the set of arbitration lines in a particular bus phase, means for supplying a local priority code to a second designated subset of the set of arbitration lines in the particular bus phase, and means, responsive to the local arbitration code and to other arbitration codes on the set of arbitration lines, and responsive to the local priority code and other priority codes on the set of arbitration lines, for detecting an arbitration win during the particular bus phase;

address means, coupled to a set of address lines of the bus and to the local data processing module, responsive to the control means for selectively supplying addresses to, and sampling addresses on the set of address lines in bus phases;

data means, coupled to a set of data lines of the bus and to the local data processing module, responsive to the control means for selectively supplying data to, and sampling data on the set of data lines in bus phases.

2. The bus interface of claim 1, wherein the control means detects arbitration phases, address phases and data phases, and the arbitration logic is responsive to arbitration phases, the address means is responsive to address phases and the data means is responsive to data phases.

3. The bus interface of claim 2, wherein the address phases and data phases are non-overlapping in time, and the set of address lines is a subset of the set of data lines.

4. The bus interface of claim 2, wherein the arbitration phases and the address phases are non-overlapping in time, and the set of arbitration lines is a subset of the set of address lines.

5. The bus interface of claim 2, wherein the arbitration phases, the address phases and the data phases are non-overlapping in time, and the set of arbitration lines is a subset of the set of address lines, and the set of address lines is a subset of the set of data lines.

6. The bus interface of claim 2, wherein the arbitration phases, the address phases and the data phases are non-overlapping in time, the set of arbitration lines and the set of address lines are respective subsets of the set of data lines.

7. The bus interface of claim 2, wherein arbitration phases begin and end on negative clock edges and address and data phases begin and end on positive clock edges.

8. The bus interface of claim 2, wherein arbitration phases begin and end on positive clock edges and address and data phases begin and end on negative clock edges.

9. The bus interface of claim 1, further including a register, accessible through the address means and the data means, which stores an arbitration identifier indicating the first designated subset of the arbitration lines for the local arbitration signal.

10. The bus interface of claim 1, further including an arbitration mask register, coupled to the means for detecting an arbitration win, and accessible through the address means and the data means, which stores an arbitration mask indicating subsets of the arbitration lines designated for other data processing modules on the bus.

11. A bus interface for connection of a local data processing module to a tri-state bus, comprising:

control means, coupled to the bus and the local data processing module, for detecting arbitration phases, address phases and data phases for transfers on the bus;

arbitration logic, coupled to a set of arbitration lines of the bus and responsive to the control means, which arbitrates for transfers during arbitration phases, including means for supplying a local arbitration code to a first designated subset of the set of arbitration lines and tri-stating the other lines in the set of arbitration lines, in a particular arbitration phase for a particular transfer, and means, responsive to the local arbitration code and to other arbitration codes on the set of arbitration lines, for detecting an arbitration win for the particular transfer;

address means, coupled to a set of address lines of the bus and to the local data processing module, responsive to the control means for selectively supplying addresses to, and sampling addresses on the set of address lines in address phases;

data means, coupled to a set of data lines of the bus and to the local data processing module, responsive to the control means for selectively supplying data to, and sampling data on the set of data lines in data phases;

wherein the arbitration phases, the address phases and the data phases are non-overlapping in time, and the set of arbitration lines is a subset of the set of address lines, and the set of address lines, is a subset of the set of data lines.

12. The bus interface of claim 11, wherein the means for detecting an arbitration win for the particular transfer generates a signal indicating arbitration win or lose during the particular arbitration phase.

13. The bus interface of claim 11, wherein the arbitration logic further includes:

bus request means, coupled to a bus request line on the bus, the means for detecting an arbitration win and the local data processing module, responsive to the control means for sampling bus request signals on the bus request line during bus phases, and supplying a bus request signal on the bus request line during a particular bus phase if the local data processing module signals a need for the bus and there was no previously asserted bus request signal on the bus from another module on the bus, or if a bus request signal was supplied by the bus request means during a preceding arbitration phase, the local data processing module continues to signal a need for the bus and an arbitration win is not detected, so that a multi-phase bus cycle is entered to serve a group of modules on the bus which assert the bus request signal during the particular bus phase.

14. The bus interface of claim 13, wherein the arbitration phases include initial arbitration phases between transfers and inter-arbitration phases between address and data phases within transfers, and the arbitration logic includes:

lock means, coupled to a lock line on the bus, the means for detecting an arbitration win and the local data processing module, responsive to the control means for selectively sampling the lock line if an arbitration win was not detected in a preceding arbitration phase, and driving the lock line during an inter-arbitration phase if the local data processing module continues to signal a need for the bus and an arbitration win was detected in the preceding arbitration phase; and

means, coupled to the lock line of the bus, responsive to an asserted lock signal on the bus for disabling arbitration by the local data processing module for the bus during the inter-arbitration phase.

15. The bus interface of claim 11, wherein the arbitration phases include initial arbitration phases between transfers and inter-arbitration phases between address and data phases within transfers, and the arbitration logic further includes:

lock means, coupled to a lock line on the bus, the means for detecting an arbitration win and the local data processing module, responsive to the control means for selectively sampling the lock line if an arbitration win was not detected in a preceding arbitration phase, and driving the lock line during an inter-arbitration phase if the local data processing module continues to signal a need for the bus and an arbitration win was detected in the preceding arbitration phase; and

means, coupled to the lock line of the bus, responsive to an asserted lock signal on the bus for disabling arbitration by the local data processing module for the bus during the inter-arbitration phase.

16. The bus interface of claim 11, wherein the arbitration means includes means for supplying a local priority code to a second designated subset of the set of arbitration lines in the particular arbitration phase, and the means for detecting an arbitration win is further responsive to the local priority code and other priority codes on the set of arbitration lines.

17. The bus interface of claim 11, further including a register, accessible through the address means and the data means, which stores an arbitration identifier indicating the first designated subset of the arbitration lines for the local arbitration signal.

18. The bus interface of claim 17, further including an arbitration mask register, coupled to the means for detecting an arbitration win, and accessible through the address means and the data means, which stores an arbitration mask indicating subsets of the arbitration lines connected to other data processing modules on the bus.

19. The bus interface of claim 11, wherein arbitration phases begin and end on negative clock edges and address and data phases begin and end on positive clock edges.

20. The bus interface of claim 11, wherein arbitration phases begin and end on positive clock edges and address and data phases begin and end on negative clock edges.

21. A bus interface for connection of a local data processing module to a bus, comprising:

control means, coupled to the bus and the local data processing module, for detecting arbitration phases, address phases and data phases for transfers on the bus;

arbitration logic, coupled to a set of arbitration lines of the bus and responsive to the control means, which arbitrates for transfers during arbitration phases, including means for supplying a local arbitration code to a first designated subset of the set of arbitration lines in a particular arbitration phase for a particular transfer, means for supplying a local priority code to a second designated subset of the set of arbitration lines in the particular arbitration phase, and means, responsive to the local arbitration code and the local priority code, and to other arbitration codes and priority codes on the set of arbitration lines, for detecting an arbitration win for the particular transfer during the particular arbitration phase;

address means, coupled to a set of address lines of the bus and to the local data processing module, responsive to the control means for selectively supplying addresses to, and sampling addresses on the set of address lines in address phases;

data means, coupled to a set of data lines of the bus and to the local data processing module, responsive to the control means for selectively supplying data to, and sampling data on the set of data lines in data phases; and

bus request means, coupled to a bus request line on the bus, the means for detecting an arbitration win and the local data processing module, responsive to the control means for sampling bus request signals on the bus request line during bus phases, and supplying a bus request signal on the bus request line during a particular bus phase if the local data processing module signals a need for the bus and there was no previously asserted bus request signal on the bus from another module on the bus, or if a bus request signal was supplied by the bus request means during a preceding arbitration phase, the local data processing module continues to signal a need for the bus and an arbitration win is not detected, so that a multi-phase bus cycle is entered to serve a group of modules on the bus which assert the bus request signal during the particular bus phase;

wherein the arbitration phases, the address phases and the data phases are non-overlapping in time, and the set of arbitration lines is a subset of the set of address lines, and the set of address lines is a subset of the set of data lines.

22. The bus interface of claim 21, wherein the arbitration phases include initial arbitration phases between transfers and inter-arbitration phases between address and data phases within transfers and the arbitration logic includes:

lock means, coupled to a lock line on the bus, the means for detecting an arbitration win and the local data processing module, responsive to the control means for selectively sampling the lock line if an arbitration win was not detected in a preceding arbitration phase, and driving the lock line during an inter-arbitration phase if the local data processing module continues to signal a need for the bus and an arbitration win was detected in the preceding arbitration phase; and

means, coupled to the lock line of the bus, responsive to an asserted lock signal on the bus for disabling arbitration by the local data processing module for the bus during the inter-arbitration phase.

23. The bus interface of claim 21, further including a register, accessible through the address means and the data means, which stores an arbitration identifier indicating the subset of the arbitration lines for the local arbitration signal.

24. The bus interface of claim 23, further including an arbitration mask register, coupled to the means for detecting an arbitration win, and accessible through the address means and the data means, which stores an arbitration mask indicating subsets of the arbitration lines connected to other data processing modules on the bus.

25. The bus interface of claim 21, wherein the set of data lines have a high-impedance state and the arbitration logic includes means for driving data lines in the set of arbitration lines other than the first and second designated subsets to the high impedance state.