Input/output device including a host interface for processing function level reset requests and updating a timer value corresponding to a time until application hardware registers associated with the function level reset requests are available

A system comprising:

• one or more processing units each configured to execute operating system software and one or more application device software drivers;
• and
• an input/output (I/O) device coupled to each of the one or more processing units via a respective communication link;
• wherein the I/O device includes:
• a plurality of application hardware resources;
• and
• a host interface coupled to the plurality of application hardware resources, wherein the host interface includes:
• a control unit;
• a plurality of groups of configuration space registers, each group corresponding to one of a plurality of functions;
• wherein each function includes one or more application hardware registers, wherein at least one of the application hardware registers is associated with a respective application hardware resource;
• and
• a plurality of application availability registers, each associated with a respective function and configured to indicate whether the one or more application hardware registers within the respective function are available for access by a corresponding application device software driver;
• wherein in response to receiving a request for a function level reset (FLR) of a particular function, the control unit is configured to:
• cause the associated application availability register to indicate that the one or more application hardware registers within the particular function is not available to the corresponding application device driver;
• reset the corresponding group of configuration space registers accessed by system software within a predetermined amount of time;
• reset the associated application hardware resources;
• and
• update a timer field of the application availability register at predetermined intervals, wherein the timer field includes a value corresponding to a time until the one or more application hardware registers are available.

A method comprising:

• providing an input/output (I/O) device having a host interface including a plurality of groups of configuration space registers accessible by system software, each group corresponding to one of a plurality of functions;
• wherein each function includes one or more application hardware registers, wherein at least one of the application hardware registers is associated with a respective application hardware resource;
• providing a plurality of application availability registers, each associated with a respective function and indicating whether the one or more application hardware registers within the respective function are available for access by a corresponding application device software driver;
• wherein in response to receiving a request for a function level reset (FLR) of a particular function, processing the FLR request by:
• causing the associated application availability register to indicate that the one or more application hardware registers within the particular function is not available to the application device software driver;
• resetting the corresponding group of configuration space registers within a predetermined amount of time;
• resetting the associated application hardware resources;
• and
• updating a timer field of the application availability register at predetermined intervals, wherein the timer field includes a value corresponding to a time until the one or more application hardware registers are available.