That dmesg command gives me more
bash-4.2$ dmesg |grep i8042
i8042: PNP: PS/2 Controller [PNP0303:C24A,PNP0f13:C24B] at 0x60,0x64 irq 1,12
i8042: Detected active multiplexing controller, rev 1.1
serio: i8042 KBD port at 0x60,0x64 irq 1
serio: i8042 AUX0 port at 0x60,0x64 irq 12
serio: i8042 AUX1 port at 0x60,0x64 irq 12
serio: i8042 AUX2 port at 0x60,0x64 irq 12
serio: i8042 AUX3 port at 0x60,0x64 irq 12
input: AT Translated Set 2 keyboard as /devices/platform/i8042/serio0/input/input0
input: SynPS/2 Synaptics TouchPad as /devices/platform/i8042/serio4/input/input1
Those greps are misleading because there can be 20 lines between stuff.
There's a couple of fancy options for this box(fingerprint wipe, etc) which I don't have. Is your system loading the keyboard or the mouse first? The interesting check thereabouts is this
sudo ls -l /sys/devices/platform/i8042/serio?
That shows me the at keyboard on serio0 and mouse on serio4