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

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Message-ID: <527923EF.4070602@ti.com>
Date:	Tue, 5 Nov 2013 18:59:27 +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 11/05/2013 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>;
}


 >
 >> - 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 */

	};


 >
 >>
 >>> +
 >>> +Example:
 >>> +
 >>> +gpio: gpio@...6000 {
 >>> +       compatible = "ti,dm6441-gpio";
 >>> +       gpio-controller;
 >>> +       reg = <0x226000 0x1000>;
 >>> +       interrupts = <42 IRQ_TYPE_EDGE_BOTH 43 IRQ_TYPE_EDGE_BOTH
 >>> +               44 IRQ_TYPE_EDGE_BOTH 45 IRQ_TYPE_EDGE_BOTH
 >>> +               46 IRQ_TYPE_EDGE_BOTH 47 IRQ_TYPE_EDGE_BOTH
 >>> +               48 IRQ_TYPE_EDGE_BOTH 49 IRQ_TYPE_EDGE_BOTH
 >>> +               50 IRQ_TYPE_EDGE_BOTH>;
 >>> +       ti,ngpio = <144>;
 >>> +       ti,davinci-gpio-irq-base = <101>;
 >>
 >>
 >>          ^^ Is it still needed?
 >>
 > OOps missed to remove that.
 >
Regards,
-grygorii

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