Re: [PATCH v8 1/2] drivers/gpio: Altera soft IP GPIO driver device tree binding

[Tien Hock Loh <thloh@altera.com>]

On Wed, 2015-01-14 at 11:01 +0100, Linus Walleij wrote:
> On Wed, Dec 24, 2014 at 9:22 AM,  <thloh@altera.com> wrote:
> 
> > From: Tien Hock Loh <thloh@altera.com>
> >
> > Adds a new driver device tree binding for Altera soft GPIO IP
> >
> > Signed-off-by: Tien Hock Loh <thloh@altera.com>
> > ---
> >  .../devicetree/bindings/gpio/gpio-altera.txt       |   43 ++++++++++++++++++++
> >  1 files changed, 43 insertions(+), 0 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/gpio/gpio-altera.txt
> >
> > diff --git a/Documentation/devicetree/bindings/gpio/gpio-altera.txt b/Documentation/devicetree/bindings/gpio/gpio-altera.txt
> > new file mode 100644
> > index 0000000..649fa02
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/gpio/gpio-altera.txt
> > @@ -0,0 +1,43 @@
> > +Altera GPIO controller bindings
> > +
> > +Required properties:
> > +- compatible:
> > +  - "altr,pio-1.0"
> > +- reg: Physical base address and length of the controller's registers.
> > +- #gpio-cells : Should be 2
> 
> Yeah.
> 
> > +  - The first cell is the gpio offset number.
> > +  - The second cell is reserved and is currently unused.
> > +- gpio-controller : Marks the device node as a GPIO controller.
> > +- interrupt-controller: Mark the device node as an interrupt controller
> > +- #interrupt-cells : Should be 1. The interrupt type is fixed in the hardware.
> > +  - The first cell is the GPIO offset number within the GPIO controller.
> > +- interrupts: Specify the interrupt.
> > +- altr,interrupt-trigger: Specifies the interrupt trigger type the GPIO
> > +  hardware is synthesized. This field is required if the Altera GPIO controller
> > +  used has IRQ enabled as the interrupt type is not software controlled,
> > +  but hardware synthesized. Required if GPIO is used as an interrupt
> > +  controller. The value is defined in <dt-bindings/interrupt-controller/irq.h>
> > +  Only the following flags are supported:
> > +    IRQ_TYPE_EDGE_RISING
> > +    IRQ_TYPE_EDGE_FALLING
> > +    IRQ_TYPE_EDGE_BOTH
> > +    IRQ_TYPE_LEVEL_HIGH
> > +
> > +Optional properties:
> > +- altr,ngpio: Width of the GPIO bank. This defines how many pins the
> > +  GPIO device has. Ranges between 1-32. Optional and defaults to 32 is not
> > +  specified.
> > +
> > +Example:
> > +
> > +gpio_altr: gpio@0xff200000 {
> > +       compatible = "altr,pio-1.0";
> > +       reg = <0xff200000 0x10>;
> > +       interrupts = <0 45 4>;
> > +       altr,ngpio = <32>;
> > +       altr,interrupt_trigger = <IRQ_TYPE_EDGE_RISING>;
> > +       #gpio-cells = <1>;
> 
> So why is there one cell in the example?
> 
> I know the second cell will describe the interrupt type that is
> anyway hardcoded but yeah, I guess it is best to work
> like all other controllers.
> 
> If you actually want it onecell that is fine too.

It should be set to two cells, I'll update this.

> 
> Yours,
> Linus Walleij

Regards
Tien Hock Loh