Using epoll with go. Packages like fsnotify does not work with sysfs. Then you need epoll, poll or select.

main.go

package main

import (
	"golang.org/x/sys/unix"
	"log"
	"os"
)

func main() {
	file, err := os.Open("/sys/class/somefile")
	if err != nil {
		log.Fatal(err)
	}

	epfd, err := unix.EpollCreate(5) // 5 is just an example, see man page.
	if err != nil {
		log.Fatal(err)
	}

	events := make([]unix.EpollEvent, 1, 5)
	events[0] = unix.EpollEvent{
		Events: unix.EPOLLPRI | unix.EPOLLHUP | unix.EPOLLERR,
		Fd:     int32(file.Fd()),
	}

	err = unix.EpollCtl(epfd, unix.EPOLL_CTL_ADD, int(file.Fd()), &events[0])
	if err != nil {
		log.Fatal(err)
	}

	bs := make([]byte, 100, 100)

	for {
		n, err := unix.EpollWait(epfd, events, -1)
		if err != nil {
			log.Fatal(err)
		}

		r, err := file.Read(bs)
		if err != nil {
			log.Fatal(err)
		}
   		// seek to beginning to relatch event
		file.Seek(0, 0)
		log.Printf("%v %v %v", n, r, string(bs[0:r]))

	}
}