<Query> How to read arguments from a gpio handle

[Leela Krishna Amudala]

Hello,

On Fri, Aug 3, 2012 at 10:58 AM, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 08/02/2012 09:39 PM, Leela Krishna Amudala wrote:
>> Hello,
>>
>> Can some one please tell me how to read the args from the gpio handle
>>
>> For example:
>> Consider    lcd-reset-gpio = <&gpx0 1 2 3 4>; as my phandle.
>>
>> The 4 args in the above handle denotes
>>
>> <[phandle of the gpio controller node]
>>       [pin number within the gpio controller]
>>       [mux function]
>>       [pull up/down]
>>       [drive strength]>
>>
>> My intention is to read the "mux function" and "pull up/down" values
>> from the above handle and do the corresponding operations on that
>> particular gpio.
>>
>> I tried using   of_get_named_gpio_flags(struct device_node *np, const
>> char *propname,
>>                            int index, enum of_gpio_flags *flags);
>> function and I always gets the flags value as '0' irrespective of the
>> values present in phandle of GPIO.
>
> Perhaps the GPIO controller referenced by &gpx0 has #gpio-cells=1?
>
> Alternatively, the GPIO controller's xlate function may simply be
> setting the flags value to 0, rather than deriving the value from the
> extra cells in the GPIO specifier.
>
> Either way, the mux function, pull, and driver strength should be
> represented using the pinctrl bindings not as part of the GPIO
> specifier. See Documentation/devicetree/bindings/pinctrl/pinctrl.txt for
> the basics.

I got the required values using of_parse_phandle_with_args() function.

Thanks,
Leela Krishna Amudala