整体分析了内存管理在驱动中提供的API，和SLAB实现机制，并给了例子-memory manage achieve example

对linux设备驱动编写过程中使用内存映射进行了详细描述，并且对时钟的来源进行了详细分析。-In the Linux device driver to write the process of using the memory mapping is described in detail, and the clock source for a detailed analysis.