Research On Storage Card Drivers In Embedded System

In order to conveniently and swiftly use nonvolatile embedded storage cards in the embedded Linux, it is necessary to investigate the development of the storage card drivers in the embedded Linux. Sequentially a storage subsystem can be constructed. According to the characteristics of the embedded Linux, the key techniques which are used in the storage card drivers' developing schemes are probed into in the system, such as constructing the core modules according to the device's specification, the abstraction of the device's controller, building the users' modules, dealing with the reading or writing request to the device, the hot plug management to the embedded storage cards, and so on. To implement the storage subsystem, a storage subsystem model is builded first, which includes file systems, a manager to block devices and some card drivers. Based on the model, the developing of the storage subsystem can be divided into three parts, such as the system's demand analysis, the constructing of the developing environment and the designing of the storage card's driver, which is the studying emphasis in the project.Under the technique conditions in existence, the flash card is the first selection of the embedded storage cards. While the CompactFlash storage cards, the shortened form as CF cards, are the most widely used flash cards in the embedded system at present. The development demand of the storage device must be filled in the embedded Linux while designing the drivers of the CF card. So according to the hardware characteristics of the CF card, the development environments for the CF card's two addressing modes, that is to say the memory mode and the I/O (Input/Output) mode, are separately constructed. Then based on the environment, the driver through the IDE (Integrated Drive Electronics) manager for each addressing mode of CF card is implemented, and the similarities and differences in the two modes' driver designing are compared in such aspects as key techniques, hardware environments, the interface's configuration, the bottom half disposing mode, and so on.The embedded storage cards should be used conveniently and one feature is that their hot plug can be managed. In order to implement the hot plug to such storage cards as CF card and MultiMediaCard card, the supporting environment for the hot plug manager are constructed in the embedded Linux. Then hot plug managing modules for such storage devices are implemented through the bottom operating system level and the upper application level.