Die-to-die interconnect interface and protocol for stacked semiconductor dies

An integrated circuit (IC) package, comprising:

• a first semiconductor die comprising an interface to a memory-mapped device, the first semiconductor die mounted within the IC package;
• a second semiconductor die not comprising an interface to the memory-mapped device, the second semiconductor die also mounted within the IC package;
• and
• a data bus coupling the first semiconductor die to the second semiconductor die, the data bus used to transfer a control word and a data word;
• wherein the control word comprises a data word start address that corresponds to a location in the memory-mapped device, the data word read from the location in the memory-mapped device by the first semiconductor die and transferred from the first semiconductor die to the second semiconductor die.

A method used in an integrated circuit package comprising a first semiconductor die and a second semiconductor die, the first semiconductor die coupled to a memory-mapped device, comprising:

• the second semiconductor die issuing a request to the first semiconductor die for access to the memory-mapped device;
• the first semiconductor die responding with an acknowledgement to the second semiconductor's access request;
• the second semiconductor die transferring a header to the first semiconductor die, the header comprising an address of a destination location in the memory-mapped device;
• the second semiconductor die transferring data to the first semiconductor die after transferring the header;
• and
• the first semiconductor die storing the data at the destination location.

A method used in an integrated circuit package comprising a first semiconductor die and a second semiconductor die, the first semiconductor die coupled to a memory-mapped device, comprising:

• the second semiconductor die issuing a request to the first semiconductor die for access to the memory-mapped device;
• the first semiconductor die responding with an acknowledgement to the second semiconductor's access request;
• the second semiconductor die transferring a header to the first semiconductor die, the header comprising an address of a source location in the memory-mapped device;
• the first semiconductor die reading data from the source location after transferring the header;
• and
• the first semiconductor die transferring the data to the second semiconductor die.