linux下计算PI值，创建线程、互斥锁，可以借鉴一下-PI values ​ ​ calculated under linux, create threads, mutexes, we can draw

这是一个spi模块的程序，对于深入了解linux驱动编程非常有益。其中涉及了中断、调度、多线程编程等-This is a spi-module program is very useful for in-depth understanding of the linux driver programming. Which deals with the interrupt, scheduling, multi-threaded programming