Building Complete Heterogeneous Systems-on-Chip in C: From Hardware Accelerators to CPUs

Abstract

High-Level Synthesis (HLS) dramatically accelerates the design and verification of individual components within larger VLSI systems. With most complex Integrated Circuits (ICs) being now heterogeneous Systems-on-Chip (SoCs), HLS has been traditionally used to design the dedicated hardware accelerators such as encryption cores and Digital Signal Processing (DSP) image processing accelerators. Unfortunately, HLS is a single process (component) synthesis method. Thus, the integration of these accelerators has to be performed at the RT level (Verilog or VHDL). This implies that the system-level verification needs to be performed at lower levels of abstraction, which significantly diminishes the benefits of using HLS. To address this, this work presents a methodology to generate entire heterogeneous SoCs in C. This work introduces two main contributions that enable this: first, an automatic bus generator that generates a synthesizable behavioral description of standard on-chip buses and, second, a library of synthesizable bus interfaces that allow any component in the system to send or receive data through the bus. Moreover, this work investigates the generation of processors and interfaces (peripherals) at the behavioral level as these are important parts of any SoCs, but have long been thought not to be efficiently synthesizable using HLS. Generating complete SoCs in C has significant advantages over traditional approaches. First, it enables the generation of fast cycle-accurate simulation models of the entire SoC, making the verification faster and easier. Second, it allows completely isolating the bus implementation details from the developers’ view, allowing the change between bus protocols with only minor changes in the designers’ code. Thirdly, it allows generating different SoC variants quickly by only changing the HLS synthesis options. Experimental results highlight these benefits.