FreeBSD Device Drivers

Tying Everything Together

Example 10-1 is a simple driver for an i-Opener’s LEDs (based on code written by Warner Losh). An i-Opener includes two LEDs that are controlled by bits 0 and 1 of the register located at 0x404c. Hopefully, this example will clarify any misunderstandings you may have about PMIO (and MMIO).

Note

Take a quick look at this code and try to discern some of its structure. If you don’t understand all of it, don’t worry; an explanation follows.

Example 10-1. led.c

#include <sys/param.h> #include <sys/module.h> #include <sys/kernel.h> #include <sys/systm.h> #include <sys/bus.h> #include <sys/conf.h> #include <sys/uio.h> #include <sys/lock.h> #include <sys/mutex.h> #include <machine/bus.h> #include <sys/rman.h> #include <machine/resource.h> ...