Re: [PATCH 1/3] pinctrl: Broadcom NSP GPIO-a device tree bindings

[Ray Jui]

Hi Rob,

On 12/2/2015 7:07 AM, Rob Herring wrote:
> On Tue, Dec 01, 2015 at 11:46:38PM -0500, Yendapally Reddy Dhananjaya Reddy wrote:
> > Device tree binding documentation for Broadcom NSP GPIO-a driver
>
> Bindings are for h/w, not drivers...
>
> > Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yrdreddy@xxxxxxxxxxxx>
> > ---
> >   .../devicetree/bindings/pinctrl/brcm,nsp-gpio.txt  | 80 ++++++++++++++++++++++
> >   1 file changed, 80 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/pinctrl/brcm,nsp-gpio.txt
> >
> > diff --git a/Documentation/devicetree/bindings/pinctrl/brcm,nsp-gpio.txt b/Documentation/devicetree/bindings/pinctrl/brcm,nsp-gpio.txt
> > new file mode 100644
> > index 0000000..bea4211
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pinctrl/brcm,nsp-gpio.txt
> > @@ -0,0 +1,80 @@
> > +Broadcom Northstar plus (NSP) GPIO/PINCONF Controller
> > +
> > +Required properties:
> > +- compatible:
> > +    Must be "brcm,nsp-gpio-a"
> > +
> > +- reg:
> > +    Should contain the register physical address and length for each of
> > +    GPIO base, IO control registers
> > +
> > +- #gpio-cells:
> > +    Must be two. The first cell is the GPIO pin number (within the
> > +    controller's pin space) and the second cell is used for the following:
> > +    bit[0]: polarity (0 for active high and 1 for active low)
> > +
> > +- gpio-controller:
> > +    Specifies that the node is a GPIO controller
> > +
> > +- ngpios:
> > +    Number of gpios supported (58x25 supports 32 and 58x23 supports 24)
>
> 2 chips? You should have 2 compatible strings. I think this is incorrect
> use of ngpios which AIUI is not for how many lines there are, but how
> many can be used (e.g. not reserved).

I believe this is the identical GPIO controller IP that is integrated 
into two different SoC chip variants. The only difference is the 
supported number of GPIO pins.

In this case, I believe this is what Linus prefers: 1) Using a single 
compatible string (tied to the GPIO controller IP); 2) Addressing 
difference in number of GPIOs using DT property 'ngpios'.

Thanks,

Ray
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