How to utilize led(4)?

[Eugene Grosbein]

Hi!

My TL-WDR3600 has this:

# ls -l /dev/led
total 0
crw-------  1 root  wheel  0x27 Mar  9 01:00 QSS
crw-------  1 root  wheel  0x26 Mar  9 00:59 SYSTEM
crw-------  1 root  wheel  0x23 Mar  9 01:00 USB1
crw-------  1 root  wheel  0x24 Mar  9 00:59 USB2
crw-------  1 root  wheel  0x25 Mar  9 01:01 WLAN2G

I've read led(4) manual page and tried to make some LEDs turn on or off:

echo -n 1 > /dev/led/QSS
echo -n 0 > /dev/led/QSS
echo -n 1 > /dev/led/WLAN2G
echo -n 0 > /dev/led/WLAN2G etc.

But no one LED changed its state. How do I manage them?
I would like to make some LED blink while performing version upgrade, for example.