Tiered access to on chip features

摘要

In accordance with some embodiments, multiple blind debug passwords are provided. Each of a plurality of interested entities may have its own password and each password may unlock a specific set of features offered by an integrated circuit. In some embodiments each entity does not know the other passwords of the other entities. Potentially interested entities include an integrated circuit end customer, the original equipment manufacturer, the entity that provided the features to the integrated circuit and a conditional access provider. All debug features may be controlled solely via access to the debug tiers which are accessed by multiple debug passwords. Lower tier passwords are required in order to access higher tiers. Debug features may be separated into multiple tiers with more intrusive access requiring multiple debug passwords in order to gain access.

主权项

1. An apparatus comprising:
a fuse array; a controller to limit access to said fuse array, said controller to provide at least a public password-free tier for viewing only and password accessed three tiers with access to different feature sets in each tier, each tier requiring a different password, one of said passwords including more bits than the other password, such that accessing a first tier requires a first password, accessing a second tier requires the first password and a second password and accessing a third tier requires the first and second passwords and a third password; a multiplexer to receive a two bit user identification code which identifies one of four types of users, each user having a different two bit user identification code; and a gate to determine whether both the user identification code and the correct password for that user have been received, each of the four users having an assigned combination of a two bit identification code and one or more passwords, such one user can access all three tiers and the other users can access less through all the tiers.