I2C HID support: advice sought

20-100

Now that I've gained some familiarity with NetBSD sources, I'd like to go a bit further.
My Ideapad has an I2C touchpad, which isn't supported by NetBSD yet, and implementing it could be a good occasion for me to learn more about NetBSD development.
I've seen in dmesg.boot that the I2C chip is correctly detected, so I imagine the only thing missing to get a usable touchpad is the "glue" between iic0 and wsmouse0.
With a USB mouse, this seems to involve 2 layers, uhidev0 and ums0..
I guess I would need to create something similar for my I2C touchpad, iichidev0 to handle communication with the touchpad and iicms0 to make it usable as a mouse.
However, it seems I2C HID is derived from the USB HID specification, so I wonder whether iichidev0 could just "feed" ums0 instead of developing a specific driver.
The starting point I imagined is to start from uhidev to create iichidev and then modify the kernel configuration file so ums could use it.

Is my reasoning is correct?
Any other relevant advice would also be greatly appreciated. 🙂

nia

Is it not an ims(4) device? http://man.netbsd.org/ims.4

Either way looking at that driver might help you.

20-100

Thanks a lot, it seems I'll have much less work! 🙂

20-100

It seems I just need to import a couple of files from OpenBSD: sys/dev/i2c/imt.c, sys/dev/hid/hidmt.c and sys/dev/hid/hidmtvar.h.
I've found I needed to add the following lines to my kernel config to get imt.c to compile:

#HID multitouch
imt*	at ihidev? reportid ?
wsmouse* at imt? mux 0

but I haven't yet found how to do the same for sys/dev/hid/hidmt.c. I've tried to find lines for hidms.c to get some inspiration but haven't found any.
Also, I've added the new sources to the files.<srcDirName> files in the dev/hid/ and dev/i2c/ source directories but I don't know if it's of any use.

I'd be happy if someone could clarify these points for me so I can get hidmt.c to compile.

EDIT: Ooops! It appears copying the file is enough. Too many file manager windows open...