Add dev docs

Author: tiagocoutinho

docs/develop.md

@@ -57,11 +57,16 @@ Create a new rules file (ex: `/etc/udev/rules.d/80-device.rules`):
 ```
 KERNEL=="event[0-9]*", SUBSYSTEM=="input", GROUP="input", MODE:="0660"
 KERNEL=="uinput", SUBSYSTEM=="misc", GROUP="input", MODE:="0660"
+
 SUBSYSTEM=="video4linux", GROUP="video", MODE:="0660"
+
 KERNEL=="uleds", GROUP="input", MODE:="0660"
 SUBSYSTEM=="leds", ACTION=="add", RUN+="/bin/chmod -R g=u,o=u /sys%p"
 SUBSYSTEM=="leds", ACTION=="change", ENV{TRIGGER}!="none", RUN+="/bin/chmod -R g=u,o=u /sys%p"
-SUBSYSTEM=="gpio", GROUP="input", MODE:="0660"
+
+KERNEL=="gpiochip[0-9]*", SUBSYSTEM=="gpio", GROUP="input", MODE="0660"
+ACTION=="add", SUBSYSTEM=="configfs", KERNEL=="gpio-sim", RUN+="/bin/chmod 775 /sys/kernel/config/gpio-sim/%k"
+ACTION=="add", SUBSYSTEM=="configfs", KERNEL=="gpio-sim", RUN+="/bin/chown root:input /sys/kernel/config/gpio-sim/%k"
 ```
 
 Reload the rules:
@@ -78,4 +83,6 @@ $ sudo modprobe uinput
 $ sudo modprobe uleds
 $ sudo modprobe -r vivid
 $ sudo modprobe vivid n_devs=1 vid_cap_nr=190 vid_out_nr=191 meta_cap_nr=192 meta_out_nr=193
+$ sudo modprobe gpio-sim
+$ sudo python scripts/setup-gpio-sim.py
 ```