Extend device driver?

[Pol Eyschen]

On 10/09/16 17:14, Greg KH wrote:
> On Sat, Sep 10, 2016 at 04:41:34PM +0200, Pol Eyschen wrote:
>> Hi everyone,
>>
>> I want to implement some custom functions of my mouse (Madcatz RAT5) in
>> Linux, e.g custom DPI-values. As this requires writing over USB to the
>> firmware of the mouse I was thinking of writing a module to accomplish
>> this. However I don't want to reimplement a whole mouse-driver,so I
>> wanted to ask if there is a possibility of binding the device to 2
>> modules or having my module extend usbhid, so that my module would only
>> be used to perform these custom operations while usbhid stays in charge
>> of the whole "mouse business".
>
> Please just use the hidraw userspace driver/library instead, that way
> you don't have to unbind the kernel driver and everything should work
> just fine without having to touch the kernel at all.
>
> Hope this helps,
>
> greg k-h
>

I looked at hidraw, unfortunately it doesn't work for me, as the mouse 
expects control URBs with proprietary requests, hence my thought for a 
kernel module.