psm(4) support for Elantech touchpads

[Malcolm Matalka]

Matthias Apitz <guru at unixarea.de> writes:
>
> El día Monday, July 04, 2016 a las 11:55:08AM +0300, Vladimir Kondratyev escribió:
>
>> After some investigations its turned out that some modern ElanTPs use 
>> I2C interface not PS/2
>> so they can not be handled with my patch. Its necessary to port new 
>> driver from Linux
>> https://lwn.net/Articles/496137/ or from OpenBSD where it has name 
>> imt(4)
>
> Thanks for your hint. I have to admit, that the idea it is an 'elan'
> touchpad is at the moment only a guess. As I said, the Acer C720 was at
> Acer.com for repair an issue with the touchpad and they changed the keyboard
> and touchpad (this is an visible fact). ChromeOS was working with it but the call in
> our FreeBSD src/sys/dev/cyapa/cyapa.c:
>
> ...
> static int
> cyapa_probe(device_t dev)
> {
>         struct cyapa_cap cap;
>         int addr;
>         int error;
>
>         addr = smbus_get_addr(dev);
>
>         /*
>          * 0x67 - cypress trackpad on the acer c720
>          * (other devices might use other ids).
>          */
>
>         device_printf(dev, "cyapa_probe(): addr %02x\n", addr);
>         if (addr != 0x67)
>                 return (ENXIO);
>         ...
>
>
> now returns 0x15 and not 0x67, and so the cyapa.ko does not attach anymore
> not even when I change the test to 0x15, which leaded to the guess of Elan TP.
>
> I will try to make some NetBSD or OpenBSD USB boot key to first verify
> what we do have here as hardware. Or any other idea to figure out, what
> Acer now installed?

I'm on an ASUS ZenBook UX305CA and have the same problem with the
trackpad.  I'm pretty sure it's an ElanTech as well, however the IRQ
cannot be allocated.  I'd like to help out but I have no idea how
anything outside userspace works.  Any suggestions for how to help?  I'm
so ignorant I'm not even sure how to go about porting something from
another OS over.

/Malcolm