Using gpio from device tree on platform devices.

[victorascroft at gmail.com]

On 15-08-21 12:29:49, victorascroft at gmail.com wrote:
> 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).

Sorry my bad I did not come down to this. Did you check the function
prototype of the functions you are calling? I would recommend checking
that.

> > 
> > What is the right way to get gpio values from device tree? Is that
> > of_get_property() lines right?

Use the gpio specific of_* ones?

> > 
> > Thanks in advance,
> > Cheers
> > 
> > -- dhs
> > 
> > 
> > -- 
> > "Do or do not. There is no try"
> >   Yoda Master
> > 
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies at kernelnewbies.org
> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies