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Date: Fri, 6 Sep 2013 15:31:15 -0300
Message-ID: <CAB=2f8yEx4UPc1QeHP+bJCDadDRvBJyvTkPjztVv4VG5uoULQw@mail.gmail.com>
Subject: Re: GPIO hint meanings
From: Luiz Otavio O Souza <lists.br@gmail.com>
To: Sean Bruno <sbruno@freebsd.org>
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On 6 September 2013 14:22, Sean Bruno <sean_bruno@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.

Luiz