eSPI Safety Communication Tunneling for SoC Power State Visibility
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Solution Overview
Problem
Conventional solutions for ensuring functional safety in autonomous platforms face limitations due to limited visibility of platform power states, costly power management, dependency on SoC services, security concerns, and susceptibility to interference, particularly common cause failures.
Innovation Solution
The implementation of an enhanced serial peripheral interface (eSPI) that tunnels communications between an embedded controller and a root of trust, providing high visibility of platform power states, reducing costs by avoiding dedicated internal power rails, and mitigating security concerns by powering the embedded controller before the SoC, thus reducing interference susceptibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an agent is embedded in the SoC to ensure functional safety, then safety monitoring capability is improved, but visibility of platform power states is limited and susceptibility to interference increases
Solution Approach 1:
The system is divided into two independent parts: the SoC and the external embedded controller. The embedded controller is separated from the SoC and connected via eSPI interface, allowing independent power management and reducing susceptibility to common cause failures while maintaining safety monitoring capabilities
Solution Approach 2:
The eSPI interface acts as an intermediary communication channel between the embedded controller and the SoC. This intermediary enables safe data exchange for functional safety operations while maintaining electrical and logical isolation, reducing direct interference susceptibility
2Use of energy by moving object
If dedicated internal power rails and power management controllers are used in SoC, then power management capability is improved, but cost increases
Solution Approach 1:
The power management functionality is extracted from the SoC and relocated to an external embedded controller. This eliminates the need for costly dedicated internal power rails and power management controllers within the SoC, reducing overall system cost while maintaining power management capability
Solution Approach 2:
The external embedded controller serves multiple functions: it manages power states, monitors functional safety, and communicates with the SoC via eSPI. This multi-functional approach replaces multiple specialized components that would otherwise be needed within the SoC
3Loss of information
If the embedded controller powers on before the SoC, then visibility of platform power states is improved, but dependency on SoC services is reduced
Solution Approach 1:
The embedded controller is designed to power on before the SoC and remain operational independently. This preliminary operation enables the controller to monitor power states from the beginning and perform safety functions without relying on SoC services, while still maintaining communication capability when needed
Data Source
AI summary
Methods, systems and apparatuses may provide for technology that includes a system on chip (SoC) having a root of trust and an embedded controller to conduct functional safety operations and non-functional safety operations with respect to the SoC. The technology may also include an enhanced serial peripheral interface (eSPI) coupled to the SoC and the embedded controller, wherein the eSPI is to tunnel communications associated with the functional safety operations between the embedded controller and the root of trust.