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SD卡作为媒体存储设备应用广泛,但很多SoC并未设计SDIO接口,故这种SoC只能通过SPI与SD卡通信,不能直接使用linux内核提供的现有的SD卡驱动。Bitbang协议是一种GPIO模拟SPI接口与SD卡通信的协议。Platform_driver是2.6版本内核以后新提出的驱动结构,有着规范和高效的特点。针对这种情况,采用了Bitbang协议和Platform架构,提出了一种基于SPI模式的SD卡驱动的解决方案。对Bitbang协议和Platform_driver结构的原理和实现方法进行了较为详细的论述,对驱动进行了测试,并最终给出了测试结果。
SD cards are widely used as media storage devices. However, many SoCs do not design SDIO interfaces. Therefore, such SoCs can only communicate with SD cards through SPIs and can not directly use the existing SD card drivers provided by the Linux kernel. Bitbang protocol is a GPIO analog SPI interface and SD card communication protocol. Platform_driver is the newly proposed driver architecture for the 2.6 kernel, with its normative and efficient features. In view of this kind of situation, has adopted Bitbang agreement and Platform architecture, has proposed one kind based on the SPI pattern SD card actuation solution. The principle and implementation of Bitbang protocol and Platform_driver structure are discussed in detail, the driver is tested, and finally the test result is given.