Embedded Software for SoC - Grupo de Mecatrônica EESC/USP

Chapter 14
INTRODUCTION TO HARDWARE
ABSTRACTION LAYERS FOR SOC
Sungjoo Yoo and Ahmed A. Jerraya
TIMA Laboratory, Grenoble, France
Abstract. In this paper, we explain hardware abstraction layer (HAL) and related issues in the
context of SoC design. First, we give a HAL definition and examples of HAL function. HAL
gives an abstraction of HW architecture to upper layer software (SW). It hides the implementation
details of HW architecture, such as processor, memory management unit (MMU), cache,
memory, DMA controller, timer, interrupt controller, bus/bus bridge/network interface, I/O
devices, etc. HAL has been used in the conventional area of operating system to ease porting
OSs on different boards. In the context of SoC design, HAL keeps still the original role of
enabling the portability of upper layer SW. However, in SoC design, the portability impacts on
the design productivity in two ways: SW reuse and concurrent HW and SW design. As in the
case of HW interface standards, e.g. VCI, OCP-IP, etc., the HAL API needs also a standard.
However, contrary to the case of HW interface, the standard of HAL API needs to be generic
not only to support the common functionality of HAL, but also to support new HW architectures
in application-specific SoC design with a guideline for HAL API extension. We present
also three important issues of HAL for SoC design: HAL modelling, application-specific and
automatic HAL design.1
Key words: SoC, hardware abstraction layer, hardware dependent software, software reuse, HAL
standard, simulation model of HAL, automatic and application-specific design of HAL
1. INTRODUCTION
Standard on-chip bus interfaces have been developed to enable hardware (HW)
component reuse and integration [1, 2]. Recently, VSIA is investigating the
same analogy in software (SW) component reuse and integration with its
hardware dependent software (HdS) application programming interface (API).
It is one that is conventionally considered as hardware abstraction layer (HAL)
or board support package (BSP).
In this paper, we investigate the following questions related to HAL, especially,
for system-on-chip (SoC).
(1)
(2)
(3)
(4)
What is HAL
What is the role of HAL for SoC design
What does the HAL standard for SoC design need to look like
What are the issues of HAL for SoC design
179
A Jerraya et al. (eds.), Embedded Software for SOC, 179–186, 2003.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.