Apparatus and method for managing power consumption by I/O ports in a computer system

A computer system comprising:

• an I/O port;
• a processor, coupled to the I/O port, for executing instructions in an instruction stream provided to the processor, the processor trapping I/O operations to the I/O port to produce trapped I/O operations;
• a main memory coupled to the processor, the main memory including a system management mode (SMM) memory, the SMM memory including SMM code for checking trapped I/O operations to determine the types of the trapped I/O operations, the SMM code including:
• a first module for saving initialization parameters for the I/O port to the system management mode (SMM) memory as stored initialization parameters if the I/O type of a trapped I/O operation is a port initialization;
• a second module for emulating a trapped I/O operation if the I/O type of the trapped I/O operation is a type without data transfer through the port, the I/O port remaining in the off state during the emulating of the trapped I/O operation;
• a third module for turning the I/O port on to a powered-up state if the I/O type of the trapped I/O operation is a type with data transfer through the port.

A computer system comprising:

• an I/O port;
• a processor, coupled to the I/O port, for executing operations in an operation stream provided thereto, the processor trapping I/O operations to the I/O port to produce trapped I/O operations;
• a main memory coupled to processor, the main memory including a system management mode (SMM) memory;
• a non-volatile memory, coupled to the main memory, for storing system management (SMM) code for checking trapped I/O operations to determine the types of trapped I/O operations, the SMM code being loaded into the system memory for execution by the processor, the SMM code including:
• a first module for saving initialization parameters for the I/O port to the system management mode (SMM) memory as stored initialization parameters if the I/O type of a trapped I/O operation is a port initialization;
• a second module for emulating a trapped I/O operation if the I/O type of the trapped I/O operation is a type without data transfer through the port, the I/O port remaining in the off state during the emulating of the trapped I/O operation;
• a third module for turning the I/O port on to a powered-up state if the I/O type of the trapped I/O operation is a type with data transfer through the port.

A method of operating a computer including an I/O port comprising the steps of:

• maintaining the I/O port in an off state when the computer is initialized;
• trapping I/O operations to the I/O port;
• keeping the I/O port in the off state until an I/O operation is trapped which involves an actual data transfer through the I/O port;
• and
• turning the I/O port on to a powered-up state when an I/O operation is trapped which involves an actual data transfer through the I/O port.

A method of operating a computer including an I/O port comprising the steps of:

• maintaining the I/O port in an off state when the computer is initialized;
• trapping an I/O operation to the I/O port;
• checking the I/O type of the I/O operation;
• saving initialization parameters for the I/O port to a system management mode (SMM) memory as stored initialization parameters if the I/O type of the I/O operation is an I/O port initialization;
• emulating the I/O operation if the I/O type is that of an I/O activity without data transfer through the port, the I/O port remaining in the off state during the emulating step;
• and
• turning the I/O port on to a powered-up state if the I/O type is that of an I/O activity with data transfer through the I/O port.

A method of operating a computer including an I/O port comprising the steps of:

• maintaining the I/O port in an off state when the computer is initialized;
• trapping an I/O operation within an address range assigned to the I/O port thus producing a trapped I/O operation;
• entering system management mode by the computer when a trapped I/O operation occurs;
• checking the I/O type of the trapped I/O operation;
• and
• if the I/O type of the trapped I/O operation is as I/O port initialization and the trapped I/O operation includes initialization parameters, then saving the initialization parameters for the I/O port to a system management mode (SMM) memory as stored initialization parameters;
• if the I/O type of the trapped I/O operation is that of an I/O activity without data transfer through the I/O port, then emulating the trapped I/O operation, the I/O port remaining in a power conserving state during this emulating step;
• if the I/O type of the trapped I/O operation is that of an I/O activity with data transfer through the port, then turning the I/O port on to a powered-up state.