Re: [PATCH v4 4/6] gpio: davinci: add OF support

[Grygorii Strashko]

On 11/06/2013 12:08 PM, Prabhakar Lad wrote:
> Hi Grygorii,
>
> On Tue, Nov 5, 2013 at 10:29 PM, Grygorii Strashko
> <grygorii.strashko@xxxxxx> wrote:
> > On 11/05/2013 10:53 AM, Prabhakar Lad wrote:> Hi Grygorii,
> >
> > > Thanks for the review.
> > >
> > > On Mon, Nov 4, 2013 at 11:58 PM, Grygorii Strashko
> > > <grygorii.strashko@xxxxxx> wrote:
> > > > Hi Prabhakar Lad,
> > > >
> > > >
> > > > On 11/02/2013 05:39 PM, Lad, Prabhakar wrote:
> > > > > From: KV Sujith <sujithkv@xxxxxx>
> > > > >
> > > > > This patch adds OF parser support for davinci gpio
> > > > > driver and also appropriate documentation in gpio-davinci.txt
> > > > > located at Documentation/devicetree/bindings/gpio/.
> > > >
> > > >
> > > > I worry, do we need to have gpio_chip.of_xlate() callback implemented?
> > >
> > > I looked for the other OF GPIO implementations with same "ngpio"
> > > property (marvel, msm) but I don’t see of_xlate() callback implemented.
> >
> > The question: will below definitions in DT work or not after this series?
> >   Will of_get_gpio()/of_get_named_gpio() work?
> >
> > Example1 - leds:
> >          leds {
> >                  compatible = "gpio-leds";
> >                  debug0 {
> >                          label = "green:debug0";
> >                          gpios = <&gpio 29 GPIO_ACTIVE_HIGH>;
> >                  };
> >          };
> >
> > Example2 - any dev:
> > devA {
> >          compatible = "devA";
> >          gpios = <&gpio 120 GPIO_ACTIVE_LOW>;
> >
> > }
> Agreed of_get_gpio()/of_get_named_gpio() wont work without
> xlate callback implemented, but I think this can be added as a
> incremental patch later.
>
> > > > - From one side, Davinci GPIO controller in DT described by one entry
> > > > which defines number of supported GPIOs as "ti,ngpio = <144>;"
> > > >
> > > > - From other side, on Linux level more than one gpio_chip objects are
> > > > instantiated (one per each 32 GPIO).
> > > >
> > > > How the standard GPIO biding will work in this case? .. And will they?
> > > >
> > > > Linus, I'd very appreciate if you will be able to clarify this point.
> > > >
> > > >
> > > > > Signed-off-by: KV Sujith <sujithkv@xxxxxx>
> > > > > Signed-off-by: Philip Avinash <avinashphilip@xxxxxx>
> > > > > [prabhakar.csengg@xxxxxxxxx: simplified the OF code, removed
> > > > >                   unnecessary DT property and also simplified
> > > > >                   the commit message]
> > > > > Signed-off-by: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > > > ---
> > > > >     .../devicetree/bindings/gpio/gpio-davinci.txt      |   32
> > > > > ++++++++++++
> > > > >     drivers/gpio/gpio-davinci.c                        |   54
> > > > > ++++++++++++++++++--
> > > > >     2 files changed, 83 insertions(+), 3 deletions(-)
> > > > >     create mode 100644
> > > > > Documentation/devicetree/bindings/gpio/gpio-davinci.txt
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/gpio/gpio-davinci.txt
> > > > > b/Documentation/devicetree/bindings/gpio/gpio-davinci.txt
> > > > > new file mode 100644
> > > > > index 0000000..55aae1c
> > > > > --- /dev/null
> > > > > +++ b/Documentation/devicetree/bindings/gpio/gpio-davinci.txt
> > > > > @@ -0,0 +1,32 @@
> > > > > +Davinci GPIO controller bindings29
> >
> > > > > +
> > > > > +Required Properties:
> > > > > +- compatible: should be "ti,dm6441-gpio"
> > > > > +
> > > > > +- reg: Physical base address of the controller and the size of memory
> > > > > mapped
> > > > > +       registers.
> > > > > +
> > > > > +- gpio-controller : Marks the device node as a gpio controller.
> > > > > +
> > > > > +- interrupts: Array of GPIO interrupt number.
> > > >
> > > >
> > > > May be meaning of <interrupts> property need to be extended, because,
> > > > as of now, only banked or unbanked IRQs are supported - and not both.
> > > OK
> > >
> > > > > +
> > > > > +- ti,ngpio: The number of GPIO pins supported.
> > > > > +
> > > > > +- ti,davinci-gpio-unbanked: The number of GPIOs that have an individual
> > > > > interrupt
> > > > > +                            line to processor.
> > > >
> > > >
> > > > Should interrupt-controller; specifier be added here?
> > > No
> >
> > So, it would be impossible to map GPIO IRQ to device through DT. Right?
> > Like:
> >          devX@0 {
> >                  compatible = "devX";
> >                  interrupt-parent = <&gpio>;
> >                  interrupts = <50 IRQ_TYPE_EDGE_FALLING>; /* gpio line 50 */
> >
> >
> >          };
> may be I took you wrong here, the interrupt-controller is inherited
> property taken from its parent, so didn’t mention that in the documentation

The GPIO controller uses interrupts form parent controller INTC/GIC
from one side, but from other side it can provide interrupts to its
users.
And as result can be interrupt-controller.

INTC/GIC -> GPIO -> user

It could work for banked IRQs only now :)


> Regards,
> --Prabhakar Lad

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