【作者】 宗志刚；

【导师】 陆生礼；

【作者基本信息】 东南大学 ， 微电子学与固体电子学， 2005， 硕士

【摘要】 设备驱动是嵌入式操作系统中的重要组成部分,其中块设备驱动又是嵌入式设备驱动的重要组成,因为系统程序通常存放在块设备中,其运行效率对系统的整体性能有着很大的影响。本文介绍了嵌入式Linux中块设备的基本概念,设计并实现了以Intel XScale系列处理器PXA255为核心,采用嵌入式Linux操作系统的个人移动终端产品中的几类通用块设备驱动,包括RAM设备、基于Flash memory的MTD(Memory Technology Device)设备以及MMC(MultiMediaCard)存储设备等驱动。本文首先介绍了RAM作为块设备在系统中的实现过程以及其挂接EXT2文件系统的方法。接着详细分析了一种新的基于Flash memory而设计的块设备- MTD设备的实现原理,通过为Flash设备抽象定义共同的属性和操作接口函数实现了Flash设备更高效的读写特性和更好的支持。当前的Flash memory主要有两种形式:NOR Flash和NAND Flash,其中NAND Flash有高容量、低成本的特点,但其相对复杂的接口给其应用带来了很大难度。本文结合业界不同方案,设计并实现了不增加任何硬件成本,使用GPIO来控制NAND Flash的方法,并在其上加载了目前非常流行的JFFS2文件系统。同时,为了提高系统工作效率,本文设计并实现了在NAND Flash上同时挂接JFFS2文件系统和最新的YAFFS文件系统的方案,并且进行了数据测量和功能验证。最后,针对于目前个人移动终端产品通常支持移动存储设备的现状,本文介绍了在系统中实现MMC设备功能的软件方案。目前,本文所描述的各项实现工作都已经完成,并且已经在系统上稳定运行。基于本课题的个人移动终端产品也已经上市,用户反应良好。更多还原

【Abstract】 In embedded system, the driver is very important. In the period of porting system, the main task is programming the drivers. In kinds of drivers, the block driver is an important type of driver which affects the system’s performance.In kinds of memory used in embedded system, Flash is the most popular device. Many handhelds such as Phone, PDA, MP3 player, USB storage and so on, use Flash as their storage. At present in the market, there are mainly two types of Flash: one is NOR Flash which is used widely, the other is NAND Flash. NOR Flash is excellent for XIP (eXecute In Place). And its speed of random reading is fast. However, NAND Flash which is favored by the industry at present has very high packing density, and the production flow is very simple. NOR Flash has the high bit-cost and the lower capacity. Howerever, NAND Flash with high capacity and low price appears the strong market competitive power, its emergence provide the very good solution for reducing the storage cost.The aim of the research is to implement and optimize the block device drivers in embedded Linux based on the XScale framework. include RAM device, MTD device and MMC card driver. Among them, MTD device is a special device which supports better manager to devices based on Flash. And now MTD device’s usage in embedded system is increasing quickly.All the work described in the paper has been finished now and has succeeded in running stably on the development platform. Meanwhile, the product based on the platform described in the paper has come into the market successfully.更多还原