Using gpio from device tree on platform devices.

[victorascroft at gmail.com]

On 15-08-20 17:53:27, Daniel. wrote:
> Hi all,
> 
> I'm trying to migrate a driver from board files to device tree. I've
> added the gpios to device tree. My device is loaded automatically,
> this is nice, but I'm facing problems while getting gpio from device
> tree using of_get_property().
> 
> 
> Here is the device tree node:
>         powerfailure {
>                 compatible = "powerfailure";
>                 poff_pfail  = <&gpio5 12 GPIO_ACTIVE_LOW>;
>                 irq_pfail   = <&gpio5 17 GPIO_ACTIVE_LOW>;
>         };

Why reinvent the wheel? May be the below is what you want?
http://lxr.free-electrons.com/source/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt

I would recommend checking first if this works for you. Don't know
what kernel you are using though.

Now coming to what you are trying to do. If you have something like below

poff-pfail-gpios = <&gpio5 12 GPIO_ACTIVE_LOW>;

struct gpio_desc *gpiod;
*gpiod = devm_gpiod_get(&pdev->dev, "poff-pail")

You can then use gpio descriptors in your call gpiod_* calls. Note that

http://lxr.free-electrons.com/source/Documentation/gpio/gpio.txt#L11

the gpio descriptor based interface is recommended and the legacy gpio
number based interface is not recommend to use anymore.

If you still want to stick to extracting information using of_* based
calls I would recommend looking at gpio specific ones.

For example, of_get_named_gpio and such....grep/vgrep for them...

-- Sanchayan.

> 
> 
> Here is my driver: http://pastebin.com/4DsRaXMS
> 
> A simple description of it. There is a circuit that triggers the
> irq_pfail at failure of power supply. The irq handler then start a
> clean shutdown. At the end of shutdown pf_power_off to cut the energy
> from the device. The logic works fine, but I'm having problems on
> pf_probe function. I got this dump:
> http://pastebin.com/paTBWwcE
> 
> So I think I'm doing something wrong with of_get_property returned
> value. I'm using the kernel 3.14.28 from freescale (iMX6 quad core
> cpu).
> 
> What is the right way to get gpio values from device tree? Is that
> of_get_property() lines right?
> 
> Thanks in advance,
> Cheers
> 
> -- dhs
> 
> 
> -- 
> "Do or do not. There is no try"
>   Yoda Master
> 
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