Writing a driver for the Corsair K90 keyboard

[Ricardo Ribalda Delgado]

Maybe http://vger.kernel.org/vger-lists.html#linux-input ?

On Mon, Aug 10, 2015 at 11:00 AM, Clément Vuchener
<clement.vuchener at gmail.com> wrote:
> It looks like no one had the answers to these questions. Is there a
> better place to ask them?
>
>> Hello.
>>
>> I first sent this email to kernel-mentors, but I got no response. So I
>> am sending it again here.
>>
>> I wrote a driver for the Corsair K90 keyboard, it is my first kernel
>> development and I have a few questions about how to properly do a few
>> things (mainly interactions with the user space).
>>
>> The Corsair Vengeance K90 is a mechanical keyboard with a backlight,
>> macro keys (G1 to G18) and some other special keys (macro recording,
>> profile switching, changing the light level or disabling the "windows
>> logo" keys). The macro playback can be switched between hardware or
>> software (from the driver not a key). Using the generic HID driver,
>> the macro keys and special keys send wrong key code or no key code at
>> all (because of the HID usage code used by the keyboard).
>>
>> The source for my driver can be found at this address:
>> https://github.com/cvuchener/k90-linux-driver . It solves the problem
>> of the generic driver and add some handling of the other features (see
>> the README for more details).
>>
>> So, my questions are about:
>>
>> - Macro keys
>> For handling the macro keys from a software, they need to send some
>> keycodes but I have no idea what to use. Currently I use F keys above
>> 12 and some MISC buttons and a parameter for changing that (at load
>> time). Are there 18 keycodes reserved for custom uses? It would also
>> be possible to send no keycode at all and use a specific software
>> listening to the hidraw or hiddev devices, but I think it would be
>> better to be able to use a generic software.
>>
>> - Backlight
>> I chose to use a led class device to manage the backlight. It seems to
>> work fine but when unregistering the driver, the light is set to 0.
>> The keyboard remembers the previous light level and so nothing should
>> be done when registering or unregistering the driver. Is the led class
>> the right class for that? or am I using it wrong?
>>
>> - Sending the macro profiles to the keyboard
>> I created a "profile" branch on my git repo for adding binary
>> attributes used for sending macro data to the keyboard. But I am not
>> sure it is a good idea, it may be better to leave that to the user space.
>>
>> Any other comment is welcome.
>>
>> Thanks,
>> Clément
>
>
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-- 
Ricardo Ribalda