On Thu, Aug 27, 2015 at 7:37 PM, Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx> wrote: Let's discuss this a bit, looping in Mark Brown. > As some of these states on some platforms are passed as physical signals > instead, the two drivers are modelled as gpio- and interrupt-controllers - > providing a nice abstraction both in device tree sense and Linux implementation > sense. I have unfortunately repeatedly encountered an argument of the type "GPIO has nice infrastructure so let's call X 'a kind of GPIO' so we can use that nice infrastructure". I'm not pleased with something that is not really general purpose input/output being called GPIO. It fits badly with the GPIO subsystem when we support things like open drain and cross-mappings to the pin control subsystem that will never be applicable to these new users. It's more like "special purpose input/output" or something. This happened with syscon LEDs for example, and was the reason I implemented syscon-leds. The original proposal was to say the LEDs register was "a kind of GPIO" on top of regmap and then use gpio-leds on top of that. Instead I insisted it was a syscon/regmap and the LEDs go directly to that, bypassing one layer of abstraction. I also imagine creating syscon-keys.c for input from arbitrary keys in a syscon register actually. Just didn't get around to that yet. I also see some of the stuff GPIO does out-of-the-box being useful, for example in MFD: some of these are interrupt controllers and basically duplicate the kind of code I have in gpiolib for GPIOLIB_IRQCHIP. So we need to figure out what is really needed. While sparsely documented: what about regmap (maybe in the form of syscon) and drivers/base/regmap/regmap-irq.c for the interrupt handling? I cannot claim to understand regmap-irq.c, but I just intuitively think it deserves consideration, such that drivers who need one of these misc registers can read/write their bits with regmap accessors and also get IRQs by way of regmap-irq. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
