Messages in this thread | | | Date | Mon, 16 Dec 2013 14:00:56 +0000 | Subject | Re: Simple MFD driver example | From | Laszlo Papp <> |
| |
Well, if you ask me the MFD subsystem is underdocumented, and there is some inconsistency between the drivers. It is hard to take any of them as a starting point, at least for me. Currently, I wrote a simple one from scratch which I will post soon.
On Mon, Dec 16, 2013 at 8:25 AM, Lee Jones <lee.jones@linaro.org> wrote: >> I have been trying to write about 50-100 LOC for 1-2 weeks now. I have >> a fairly simple use case for MFD where I need to have gpio and hwmon >> functionality for a GPIO. >> >> I read the mfd drivers inside and out by now, but it looks a bit >> inconsistent to me. I am not sure what to follow etc. The >> documentation seems to be virtually missing which makes my life and >> involvement even more difficult. :( >> >> May I ask for some pointer how to do all this? It would be nice to see >> a minimal example where the parent does not do anything else than just >> enumerating the sub-device drivers. Is that possible with an empty >> probe callback? >> >> If I understand the regmap correctly (again, it is possible I do not), >> then I would not need this. But in general, it is really hard to deal >> with the linux kernel in this regard when basic documentations are >> missing. >> >> I hope this would change over time for the posterity. It is a pity >> that contributors do not join probably due to this. It is a bit >> chaotic, but I hope it can be changed in the future. >> >> Apologies for my frustration... > > Due to the nature of the MFD subsystem, there isn't a simple use-case > which you can use as a template. It's completely dependent on the > device you are trying to enable. There are lots of well written > drivers in the subsystem that you can use as good examples though. > > Which device are you trying to write a driver for? Is there a > datasheet you can point to? > > NB: When emailing subsystem maintainers for help, please don't forget > to CC the relevant Mailing Lists. All lists can be found in the > MAINTAINERS file, which is parsed by <kernel>/scripts/get_maintainer.pl. > > -- > Lee Jones > Linaro STMicroelectronics Landing Team Lead > Linaro.org │ Open source software for ARM SoCs > Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |