Atheros AP222A, Руководство пользователя

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COMPANY CONFIDENTIAL 4
1 Introduction
This manual provides information on the design and use of the Atheros AP system. This system consists of the OS kernel,
utility functions, and the Atheros AP Driver.
1.1 Top Level architecture
This driver is based on the Atheros Universal Driver Architecture. This architecture abstracts the WLAN driver into
various common sections that can be used for a variety of operating systems. OS specific components are well isolated,
and the Atheros Driver Framework (ADF) provides abstractions of OS services such that the common code does not
have to have ANY OS specific coding. The data packet abstraction, called WBUF, allows the driver to handle different
OS specific frame formats in a common way. This abstraction has been used with both SKB and MBUF frame
architectures successfully, and also works with Windows frame architectures.
The software design is moved to a further modularized architecture that allows for better isolation of data items and
object oriented design. . Global variables are eliminated, and all layer functions are contained within a call structure.
1.2 Fusion Overview
The main driver for the Fusion architecture was the use of a common code base to support multiple operating systems.
This allows for more efficient development processes, as well as the synergy of getting bug fixes for all major platforms
at the same time.
The Fusion architecture consists of 4 major components. The first is the WLAN driver interface, which is the operating
system unique interface adaptor that translates OS specific calls to Fusion “generic” calls. The second is the Upper
MAC layer, which contains the bulk of the 802.11 protocol processing for both station and AP applications. In earlier
versions of Fusion, this layer was implemented specifically for each operating system. In later versions, a common
version of the Upper MAC is used to provide the protocol processing layer.
The third component is the Lower MAC, which contains the ATH and HAL layers. This layer is much more hardware
centric, and is designed to support the needs of the Atheros chipset architecture. The fourth component is the OS
Abstraction layer. This is a set of macros that is used to redefine “generic’ OS primitives into specific system calls that
perform the required function. Functions such as register read/write, translation of OS packets into WBUF abstractions,
and tasking control are all included in this section. A block diagram of the components and their relationship are shown
in Figure 1.