GPIO hint meanings

[Warner Losh]

On Sep 6, 2013, at 12:31 PM, Luiz Otavio O Souza wrote:

> On 6 September 2013 14:22, Sean Bruno <sean_bruno at yahoo.com> wrote:
> 
>> I think I have a fairly firm grasp on what some of the mips/gpio hints
>> mean, e.g.:
>> 
>> hint.gpio.0.pinmask
>> hint.gpioled.0.at
>> hint.gpioled.0.name
>> hint.gpioled.0.pins
>> 
>> Fairly straightforward.
>> 
>> Now, what do these mean/do:
>> 
>> hint.gpio.0.function_set
>> hint.gpio.0.function_clear
>> 
>> ?
>> 
>> Sean
>> 
>> p.s. I think I'll take this and thrash together a gpioled(4) and gpio(4)
>> man page if I can understand better.
>> 
> 
> 
> Hi Sean,
> 
> Some of the GPIO pins on this SoC family (ar724x, ar71xx and ar9xxx) can be
> set between GPIO and an alternate function. So adding a pin to function_set
> enables this alternate function and the function_clear disables it
> (sometimes the bootloader doesn't initialize properly those pins).
> 
> Each SoC has its own set of pins and functions.
> 
> For ar71xx the pins 0 and 1 can be used as additional SPI chip select
> outputs, pins 9 and 10 are used for UART and there are also reserved pins
> for a SLIC/I2S interface.


We really need a pinmux/pinctl type interface for this which is standard across drivers/platforms.

Warner