Hi Andy, On Fri, Oct 20, 2023 at 12:27:58AM +0300, andy.shevchenko@xxxxxxxxx wrote: > Thu, Oct 05, 2023 at 11:58:38AM +0900, AKASHI Takahiro kirjoitti: > > This is a revised version of my previous RFC[1]. Although I modified > > the commits to make them look SCMI-independent, they are still posted > > as RFC because I have never tested them on real hardware. > > > > (background) > > I'm currently working on implementing SCMI pinctrl/gpio drivers > > on U-Boot[2]. Although the pinctrl driver for the kernel[3] was submitted > > by EPAM, it doesn't contain the gpio driver and I believe that we should > > discuss a couple of points on the kernel side to finalize my design for > > U-Boot. > > > > So this RFC is intended for reviews, especially to raise some issues. > > > > 1) how to obtain a value on an input pin > > All the existing gpio drivers are set to obtain a value on an input > > pin by accessing the hardware directly. In SCMI case, however, this is > > just impossible in its nature and must be supported via a protocol > > using "Input-value" configuration type. (See the spec[4], table-23.) > > > > The current pinconf framework is missing the feature (the pinconf > > parameter and a helper function). See patch#1, #2 and #3. > > > > Please note that there is an issue around the pin configuration in > > EPAM's current pinctrl driver as I commented[5]. > > > > 2) DT bindings > > I would like to propose a generic binding for pinctrl based gpio driver. > > This allows a "consumer" driver to handle gpio pins like as other > > normal gpio controllers support. (patch#5) > > > > 3) generic GPIO driver > > Based on (2), I tried to prototype a generic driver in patch#4. > > Thanks to a set of existing pinctrl_gpio helper functions, except (1), > > It seems that the driver can be implemented not relying on pin controller > > specific code, at least for SCMI pinctrl. > > > > I will appreciate any comments. > > Any comment here: I'm listed as a designated reviewer of GPIO patches, why am I > not Cc'ed on this? My apologies. I will add you in Cc. > I definitely have some comments against the code (no DT, > though). Please, use (up-to-date) MAINTAINERS in your v3. Please don't hesitate to make comments here on v2 so that I can include your reviews in v3. Thanks, -Takahiro Akashi > > -- > With Best Regards, > Andy Shevchenko > >
