基于ARM9的Linux嵌入式系统移植与驱动开发

IIAbstractWiththedevelopmentoftheinformationtechnology,embeddedsystemshasbeenbroadlyappliedineachfieldoffamlilyandindustry.Andtheincreasinglywiderangeofapplications,thecomplexityofembeddedsystemsisconstantlyincreasing.Now,theembeddedoperatingsystemhasbecomeoneofthemostimportantpartoftheembeddedsystem.Intheembeddedoperatingsystems,TheLinuxoperatingsystemhasbecomemoreandmoreattened，becauseofitsopensource,smallcore,goodperformance;what’smore,Linux2.6introducesmanynewfeaturesthatmakeitanexcellentandsuitableoperatingsystemforembeddedcomputing.Undoubtedly,theembeddedLinuxoperatingsystemwillbringlargeeconomicvalueandapplicationprospects.ThisthesisisaccomplishedbasedontheautomaticmeterreadingsystemforapowercompanyinNanjing,andthemaincontributionistointroducetransplantationoftheembeddedLinuxsystem,aswellasthedriverdevelopmentofcorrespondingperipheraldevice.ThispaperaccomplishthetransplantationoftheembeddedLinuxsystembasedonAT91SAM9260EK,andincludingbuildthedevelopmentplatform,buildtheembeddedcross-compileenvironment;Basedontheanalysisofthebootingandloadingprocess—BootLoaderoftheembeddedsystem,implementsthetransplantationofUbootontheplatform.AfterthedetailedanalysisofthekernelstructureandbootingprocessofLinuxsystem,accordingtotheterminalhardwareplatform,analyzetheprocessoftransplantationandcutoftheLinuxkernel.Inaccordancewiththeapplicationrequirements,weselecttheYAFFS2asourrootfilesyetem,anddetailedlyintroducetheprocessoftheimplementationoftheYAFFS2filesystem.Finally,developthedriversoftherelatedequipment,especiallytheLCD(UC1698U),improvetheoriginalwayofdirectaccessGPIOport,andcombiningtheGPIOandframebuffertodevelopthenewdriver.Theframebufferisthecachefordisplay,writedatatothecache,thecontrollerwillautomaticallyreadthedatafromthecacheanddisplay.ThedevelopmentofGUIbasedonQt/Embeddedneedthesupportofframebuffertechnology.ButforthetypeofLCD,thedisplaycontrollercannotautomaticallyreadthedatafromthecache,usethekerneltimertoupdatetheframebufferforreal-timedisplayanddeveloptheGUIoftestbasedonQt/Embedded.Keywords:embeddedLinuxsystem,ARM9,YAFFS2,driver,FrameBufferI摘要随着信息技术的不断发展，嵌入式系统已经广泛应用于工业和家庭的各个领域。其复杂性也随之不断增加，嵌入式操作系统成为了嵌入式系统中最重要的组成部分之一。在嵌入式操作系统中，Linux操作系统得到了越来越多的关注，Linux系统开源、具有精简的内核以及优异的性能。另外，Linux2.6包含许多新的特性，为其在嵌入式领域的应用提供了更多更好的支持，嵌入式Linux系统将会有巨大的市场价值以及应用前景。本文基于南京某电力公司自动抄表系统，对负荷控制管理终端平台进行了Linux系统移植以及对LCD等外围设备的驱动开发。本系统的CPU采用ATMEL公司的以ARM926T为内核的AT91SAM9260EK处理器。采用了基于2.6内核版本的嵌入式ARMLinux，最终完成基于ARM9的嵌入式Linux系统移植开发。具体包括搭建开发平台，建立嵌入式交叉编译环境；在分析嵌入式系统引导加载程序BootLoader的基础上，结合本目标板修改Uboot源码并进行Uboot的编译和移植；通过分析嵌入式Linux系统的内核结构和启动流程，实现了针对本目标板的内核源码修改、编译以及移植；同时按照应用需求，选择YAFFS2文件系统作为根文件系统，并给出根文件系统实现的过程；最后开发终端外围设备相应的驱动程序，重点围绕LCD（UC1698U）展开，改进原来直接读写GPIO口的驱动方式，采取直接读写GPIO和帧缓冲相结合的方式开发新的驱动程序。帧缓冲是一块显示缓存，通过向该缓存中写入数据，显示控制器就会自动的从中读取数据并显示出来，在LCD设备上基于Qt的图形用户界面的开发也需要帧缓冲技术的支持。但对于本类型的LCD，显示控制器并不能自动完成缓冲区数据读取，本文从软件的角度借助内核定时器最终完成缓冲区更新并实时显示，最后开发基于Qt/Embedded的用户图形测试界面。关键词:嵌入式Linux系统，ARM9，YAFFS2文件系统，驱动，帧缓冲III目录第一章绪论..........................................................................................................................................11.1选题背景以及研究内容.............................................................................................................11.1.1选题背景.........................................................................................................................11.1.2研究内容.........................................................................................................................21.2课题来源以及论文的主要工作...................................................................................................4第二章搭建嵌入式Linux开发平台........................................................................................................52.1开发平台硬件参数....................................................................................................................52.2开发宿主机交叉编译环境的建立...............................................................................................52.2.1arm-none-Linux-gnueabi-gcc的安装...................................................................................62.2.2TFTP和NFS的配置.........................................................................................................62.3本章小结..................................................................................................................................6第三章BootLoader的设计与移植...........................................................................................................73.1BootLoader概述.........................................................................................................................73.2BootLoader的操作模式..............................................................................................................83.3Uboot的源码结构......................................................................................................................83.4Uboot的编译及其在目标板上的移植..........................................................................................93.4.1Uboot的源码修改以及编译.......................................................