Hierarchically expandable fair arbiter

A method for determining access to a resource by a hierarchical system of arbiter devices comprising:

• generating a request-out signal based on a plurality of request-in signals;
• receiving a select-in signal;
• generating a select-out signal from said select-in signal, said plurality of request-in signals and from a previous winner of access to said resource, wherein said previous winner is stored in said system, wherein said hierarchical system of arbiter devices is configurable to receive an input hold signal, said input hold signal causing a current winner of access to said resource to hold said access for a number of clock cycles, wherein further said access is relinquished after said number of clock cycles has expired only if there is a pending request for access;
• propagating a collision signal through said hierarchical system to a collision detection circuit to indicate a collision between said current winner and another of said arbiter devices;
• and
• propagating a release signal sent by said collision detection circuit in response to said collision signal through said hierarchical system to said current winner to release said access.

A device for determining access to a resource, comprising:

• a memory operable to hold a previous winner of access to said resource;
• a first logic operable to generate a request-out signal based on a plurality of request-in signals;
• and
• a second logic coupled to said memory, said second logic operable to generate a select-out signal from a select-in signal, said plurality of request-in signals and from said previous winner received from said memory, wherein said device is operable to be used in a hierarchical arbitration system and wherein said device is configurable to receive an input hold signal, said input hold signal causing said device to hold said access for a number of clock cycles, wherein further said access is relinquished after said number of clock cycles has expired only if there is a pending request for access, wherein a signal indicating a collision between said device and another device of said hierarchical arbitration system is propagated through said hierarchical arbitration system to a collision detection circuit and wherein in response said collision detection circuit sends a signal that is propagated through said hierarchical arbitration system to said device to release said access.