On Fri, Apr 29, 2016 at 2:53 AM, Christian Lamparter <chunkeey@xxxxxxxxxxxxxx> wrote: > From: Álvaro Fernández Rojas <noltari@xxxxxxxxx> > > This patch adds the device tree bindings for the gpio-mmio. > The gpio-mmio is already part of a the GPIO generic library. > > Signed-off-by: Álvaro Fernández Rojas <noltari@xxxxxxxxx> > Signed-off-by: Christian Lamparter <chunkeey@xxxxxxxxxxxxxx> I share your ambition to create something generic for this class of hardware(s). > +Bindings for the generic driver for memory-mapped GPIO controllers. > + > +Required properties: > + - compatible: should be "linux,gpio-mmio" Why? "memory-mapped-gpio" sits nicely with me. Read another very generic binding for inspiration: Documentation/devicetree/bindings/leds/register-bit-led.txt > + - reg-names: must contain > + "dat" - data register > + may contain > + "set" - data set register > + "clr" - data clear register > + "dirout" - direction output register > + "dirin" - direction input register I would just be more verbose: data-in-register data-out-set-register data-out-clear-register direction-output-register direction-input-register Some should be optional so we can support input-only and output-only GPIO controllers too. I would take this opportunity to add bindings also for stuff that the generic MMIO driver does not support today but could be made to support: open-drain-register open-source-register debounce-register etc > +Optional properties: > + - ngpio: specifies the number of gpio mapped in the register. Just reference the generic docs. > + - big-endian: force big endian register accesses. > + - big-endian-byte-order: assign GPIOs in reverse order. > + - unreadable-reg-set: data set register is not readable. > + - read-output-reg-set: cache value set for reads. > + - unreadable-reg-dir: dirout/dirin register is not readable. > + - no-output: GPIOs are read-only. I think it's better to imply that if there is no data-in-register specified, then it is output-only etc. > +The GPIO generic library provides support for memory-mapped GPIO > +controllers. The configuration is detected by which resources are present. > +The simplest form of a GPIO controller that the driver support is just a > +single "dat" register, where GPIO state can be read and/or written. > +However, the driver supports far more: > + - 8/16/32/64 bits registers. The number of GPIOs is automatically > + determined by the width of the registers. > + - GPIO controllers with clear/set registers. > + - GPIO controllers with a single "dat" register. > + - Big endian bits/GPIOs ordering. Skip this. It is Linux-specific. 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
