After the boot, I first loaded gpio-it87, and then loaded it87_wdt. GPIO driver will not be able to control the GPIO port Welcome to Ubuntu 16.04.1 LTS (GNU/Linux 4.4.0-34-generic x86_64) * Documentation: https://help.ubuntu.com * Management: https://landscape.canonical.com * Support: https://ubuntu.com/advantage 7 packages can be updated. 0 updates are security updates. Last login: Sun Aug 14 15:20:36 2016 from 192.168.1.100 zhen@ubuntu:~$ uname -a Linux ubuntu 4.4.0-34-generic #53-Ubuntu SMP Wed Jul 27 16:06:39 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux zhen@ubuntu:~$ sudo -i [sudo] password for zhen: root@ubuntu:~# lsmod | grep it87 root@ubuntu:~# modprobe gpio-it87 root@ubuntu:~# modprobe it87_wdt root@ubuntu:~# lsmod | grep it87 it87_wdt 16384 0 gpio_it87 16384 0 root@ubuntu:~# tail -n 5 /var/log/syslog Aug 14 15:27:46 ubuntu systemd[1]: Starting Stop ureadahead data collection... Aug 14 15:27:46 ubuntu systemd[1]: Stopped Read required files in advance. Aug 14 15:27:46 ubuntu systemd[1]: Started Stop ureadahead data collection. Aug 14 15:28:32 ubuntu kernel: [ 117.602802] gpio_it87: Found Chip IT8728 rev 0. 64 GPIO lines starting at 0a00h Aug 14 15:28:41 ubuntu kernel: [ 126.599025] it87_wdt: Chip IT8728 revision 0 initialized. timeout=60 sec (nowayout=0 testmode=0 exclusive=1 nogameport=0 nocir=0) root@ubuntu:~# cd /sys/class/gpio/ root@ubuntu:/sys/class/gpio# ls export gpiochip448 unexport root@ubuntu:/sys/class/gpio# echo 492 > export root@ubuntu:/sys/class/gpio# ls export gpiochip448 it87_gp64 unexport root@ubuntu:/sys/class/gpio# cd it87_gp64 root@ubuntu:/sys/class/gpio/it87_gp64# ls active_low direction power subsystem uevent value root@ubuntu:/sys/class/gpio/it87_gp64# cat direction in root@ubuntu:/sys/class/gpio/it87_gp64# echo out > direction root@ubuntu:/sys/class/gpio/it87_gp64# cat direction out root@ubuntu:/sys/class/gpio/it87_gp64# cat value 1 root@ubuntu:/sys/class/gpio/it87_gp64# echo 0 > value root@ubuntu:/sys/class/gpio/it87_gp64# cat value 1 root@ubuntu:/sys/class/gpio/it87_gp64# tail -n 5 /var/log/syslog Aug 14 15:27:46 ubuntu systemd[1]: Started Stop ureadahead data collection. Aug 14 15:28:32 ubuntu kernel: [ 117.602802] gpio_it87: Found Chip IT8728 rev 0. 64 GPIO lines starting at 0a00h Aug 14 15:28:41 ubuntu kernel: [ 126.599025] it87_wdt: Chip IT8728 revision 0 initialized. timeout=60 sec (nowayout=0 testmode=0 exclusive=1 nogameport=0 nocir=0) Aug 14 15:30:47 ubuntu systemd-timesyncd[1692]: Timed out waiting for reply from 91.189.91.157:123 (ntp.ubuntu.com). Aug 14 15:30:47 ubuntu systemd-timesyncd[1692]: Synchronized to time server 91.189.89.199:123 (ntp.ubuntu.com). root@ubuntu:/sys/class/gpio/it87_gp64#