On Thu, May 12, 2016 at 12:07:48AM +0200, Christian Lamparter wrote: > This patch adds binding information for IBM/AMCC/APM GPIO > Controllers of the PowerPC 4XX series and compatible SoCs. > > The "PowerPC 405EP Embedded Processor Data Sheet" has the > following to say about the GPIO controllers: " > > - Controller functions and GPIO registers are programmed > and accessed via memory-mapped OPB bus master accesses > > - All GPIOs are pin-shared with other functions. DCRs control > whether a particular pin that has GPIO capabilities acts > as a GPIO or is used for another purpose. > > - Each GPIO outputs is separately programmable to emulate > an open-drain driver (i.e. drives to zero, threestated if > output bit is 1) > > " > The ppc4xx_gpio.c driver is part of the platform/sysdev drivers > in arch/powerpc/sysdev. > > Signed-off-by: Christian Lamparter <chunkeey@xxxxxxxxxxxxxx> > --- > I looked into arch/powerpc/sysdev/ppc4xx_gpio.c driver and > it doesn't have support for the tri-state logic (open drain > is disabled), but the hardware would support it. > (the #gpio-cells description suffers because of this, since > the high-z option isn't there). > > Also there's another problem: There's no DCR pinmux driver?! > So sadly, there's not much information on how to use the DCRs > to control the which pin is muxed to the GPIO or to a SoC > function like the i2c. > > This was all the valuable information I could find about the > hardware, so it is included it in the binding text, even > though there's no support for it... Is there anything else > to add? > --- > .../devicetree/bindings/gpio/ibm,ppc4xx-gpio.txt | 24 ++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > create mode 100644 Documentation/devicetree/bindings/gpio/ibm,ppc4xx-gpio.txt Normally, we don't allow wildcards for compatible strings, but given this is an established binding it is okay. Acked-by: Rob Herring <robh@xxxxxxxxxx> -- 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
