Embedded Software for SoC - Grupo de Mecatrônica EESC/USP

138 Chapter 11
Another cause is that verification and debugging of a device driver is
difficult since a device driver must operate under the timing determined by
the device. In general, verification of time-dependent software takes a long
time since the operation must be verified for every possible timing. Moreover,
even though an error occurred in a software, finding the bug is difficult since
the repetition of a bug is low.
To solve this problem, we have conducted a research on an integrated
design method of a device driver (Software) and a device (Hardware) for the
efficient development of device drivers for embedded systems. This method
uses system level design and co-design technologies to describe the device
and the device driver as a unit in one language and generate the implementation
descriptions from the integrated description. This method is expected
to improve the communication between device designers and device driver
designers and to increase the efficiency of device driver development. Also
another merit that can be expected by applying co-design technology is that
the border between the device and the device driver can be flexibly changed.
In this paper, we evaluate whether SpecC [2] is applicable to the
integrated description in the proposed design method. Applicability means the
ability of SpecC to describe the device and the device driver as a unit and
automatically generate implementation descriptions from the integrated
description. SpecC is C language-based with additional concepts and statements
for enabling hardware descriptions. It is proposed as a language to cover
the range from system level description to implementation design. However,
the semantics of the added concept and statements were mainly discussed from
the viewpoint of hardware description and hardware generation and the method
to generate the software using a real-time kernel was not considered. Since a
real-time kernel is essential to construct software on a large scale system
LSI, the device driver generated by the proposed design method is assumed
to use a real-time kernel. Thus, evaluating whether SpecC is applicable to
the proposed design method is necessary.
To evaluate the applicability of SpecC, we use a serial I/O system (SIO
system) that includes the Point-to-Point Protocol (PPP) function used in
sending a TCP/IP packet on a serial line. We choose the SIO system in our
evaluation because it has a simple but typical architecture used in communication
systems which is important application of system LSI.
The rest of the paper is organized as follows: Section 2 presents the
proposed integrated design method of a device driver and a device. Section
3 describes evaluation points and methods to evaluate the applicability of
SpecC to the integrated design method. Section 4 describes description of
the SIO system in SpecC and SpecC description guidelines. Section 5 discusses
the conversion of SpecC description to implementation description. In
Section 6, we shows the conversion when partition point is changed.