Re: Simple MFD driver example

From: Laszlo Papp
Date: Wed Dec 18 2013 - 06:17:27 EST


On Wed, Dec 18, 2013 at 11:12 AM, Lee Jones <lee.jones@xxxxxxxxxx> wrote:
>> The MAX6650/6651 chip has multiple functionality:
>>
>> * fan/hwmon
>>
>> * gpio
>>
>> * alarm, etc.
>>
>> What you eventually see in hwmon is only a subset of all the features
>> the IC provides. You may want to read this thread:
>> https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg536509.html
>
> Okay, so the best thing to do is send out the entire patch-set at
> once, CC'ing each of the maintainers on every patch so we can all see
> how this thing fits together.

Well, I am not even sure currently where to head with the MFD bits and
its children subdevices currently....

I would appreciate any direction. Yesterday, I was told on IRC, I
would need to switch from i2c to platform drivers for the hwmon and
gpio parts, but looking at some existing mfd driver code and their
children drivers, I do not see it like that.

I have already sent out the gpio driver yesterday which works fine on
its own: http://www.spinics.net/lists/kernel/msg1655805.html

Could you please guide me into the right direction what I need to
change once we have standalone drivers, and they should be glued
together? I thought adding an abstraction with the mfd layer would be
sufficient, but apparently, that is not enough.

Practically speaking, I am confused since if I needed to change the
existing drivers, that means I could potentially break the interface
for the existing users if the drivers stop working on their own, but
then again, I am such a newbie that I would greatly appreciate some
pointers.
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