info from /proc/kmsg (with EVBUG enabled)
keyboard open:
<7>[  179.884216] evbug: Event. Dev: input3, Type: 5, Code: 0, Value: 0
<7>[  179.884918] evbug: Event. Dev: input3, Type: 0, Code: 0, Value: 0

keyboard close:
<7>[  234.442993] evbug: Event. Dev: input3, Type: 5, Code: 0, Value: 1
<7>[  234.443389] evbug: Event. Dev: input3, Type: 0, Code: 0, Value: 0

device info from /froc/bus/input/devices:
I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="vision-keypad"
P: Phys=
S: Sysfs=/devices/virtual/input/input3
U: Uniq=
H: Handlers=kbd event3 evbug keyreset
B: PROP=0
B: EV=23
B: KEY=10000 0 2d80000 3800000 400800 1c0010 0 35ff47f d3ff4000
B: SW=1