说明：  宋宝华著的《Linux驱动学习和关键技术》pdf版电子书下载，嵌入式培训专家，讲述总线、设备与驱动、Plantform设备、驱动和总线、Linux设备驱动的分层思想
(Song Baohua's "Linux-driven learning and key technologies" pdf version of the e-book download, embedded training experts, talk about the layered ideas of bus, device and driver, Plantform device, driver and bus, Linux device driver)