Host-device interface for debug authentication

A method for managing communications in an electronic device, the method comprising:

• providing a communications interface for debugging purposes via a debug port;
• coupling a first processing unit to the debug port via a first of a plurality of processing unit access ports;
• selectively setting each of the plurality of processing unit access ports to one of:
• an open state, wherein communications to and from the debug port are relayed;
• and
• a closed state, wherein communications to and from the debug port are blocked;
• authenticating an external device using an authentication interface circuit;
• coupling the debug port to the authentication interface circuit via a further access port, wherein in an open state, communications are relayed between the debug port and the authentication interface circuit;
• reading, by the external device, a status register in the authentication interface circuit via the debug port and the further access port;
• storing, in the status register, an indication of the open or closed state of each of the plurality of processing unit access ports;
• reading, by the external device via the debug port and the further access port, states of each of the plurality of processing unit access ports stored by the status register;
• and
• initiating, by the external device, the debug of one or more of the plurality of processing unit access ports that is in the open state.

An electronic device, comprising:

• a debug port providing a communications interface for debugging purposes;
• a first processing unit;
• a plurality of processing unit access ports coupled to the debug port, a first of the plurality of processing unit access ports being coupled between the debug port and the first processing unit, each of the plurality of processing unit access ports being configured to be in one of an open state in which it relays communications to and from the debug port and a closed state in which it blocks communications to and from the debug port;
• an authentication interface circuit configured to authenticate an external device;
• and
• a further access port coupled between the debug port and the authentication interface circuit, the further access port being configured to be in an open state, in which communications are relayed between the debug port and the authentication interface circuit, prior to release of a reset state of the electronic device during power-up and during boot when an authentication request is received from the external device.