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Message-ID: <527A2E1E.8030308@ti.com>
Date: Wed, 6 Nov 2013 13:55:10 +0200
From: Grygorii Strashko <grygorii.strashko@...com>
To: Prabhakar Lad <prabhakar.csengg@...il.com>
CC: Sekhar Nori <nsekhar@...com>,
Linus Walleij <linus.walleij@...aro.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
Rob Herring <rob.herring@...xeda.com>,
Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Stephen Warren <swarren@...dotorg.org>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Rob Landley <rob@...dley.net>,
Russell King <linux@....linux.org.uk>,
Grant Likely <grant.likely@...aro.org>,
Alex Elder <alex.elder@...aro.org>,
LDOC <linux-doc@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
LAK <linux-arm-kernel@...ts.infradead.org>,
dlos <davinci-linux-open-source@...ux.davincidsp.com>,
"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH v4 4/6] gpio: davinci: add OF support
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@...com> 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@...com> wrote:
>>>> Hi Prabhakar Lad,
>>>>
>>>>
>>>> On 11/02/2013 05:39 PM, Lad, Prabhakar wrote:
>>>>>
>>>>> From: KV Sujith <sujithkv@...com>
>>>>>
>>>>> 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@...com>
>>>>> Signed-off-by: Philip Avinash <avinashphilip@...com>
>>>>> [prabhakar.csengg@...il.com: simplified the OF code, removed
>>>>> unnecessary DT property and also simplified
>>>>> the commit message]
>>>>> Signed-off-by: Lad, Prabhakar <prabhakar.csengg@...il.com>
>>>>> ---
>>>>> .../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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