Re: [PATCH v3] gpio: add GPIO support for F71882FG and F71889F

From: Linus Walleij
Date: Mon Jul 29 2013 - 11:59:17 EST

On Mon, Jul 22, 2013 at 11:50 AM, Simon Guinot
<simon.guinot@xxxxxxxxxxxx> wrote:

> This patch adds support for the GPIOs found on the Fintek super-I/O
> chips F71882FG and F71889F.
> A super-I/O is a legacy I/O controller embedded on x86 motherboards. It
> is used to connect the low-bandwidth devices. Among others functions the
> F71882FG/F71889F provides: a parallel port, two serial ports, a keyboard
> controller, an hardware monitoring controller and some GPIO pins.
> Note that this super-I/Os are embedded on some Atom-based LaCie NASes.
> The GPIOs are used to control the LEDs and the hard drive power.
> Signed-off-by: Simon Guinot <simon.guinot@xxxxxxxxxxxx>
> ---
> Changes since v2:
> - Remove useless NULL setters for driver data.

Given the recent discussion with Rafael I want to have an
extended discussion of this patch.

It is my current understanding that:

- It is possible to define the whereabouts of the SuperIO
chips using ACPI
- It is possible for developers to influence the source
AML for the DSDT tables of these systems.
- It is the proper thing to do.
- So we should atleast support ACPI probing with the
port-based detection as a final fallback if all else fails.

Why can I not get something like:

#include <linux/acpi.h>
static const struct acpi_device_id gpio_acpi_match[] = {
{ "FOOBAR", 0 },
{ }
MODULE_DEVICE_TABLE(acpi, gpio_acpi_match);

static struct platform_driver gpio_driver = {
.driver = {
.acpi_match_table = ACPI_PTR(gpio_acpi_match),


If there is something wrong in my reasoning above, please
share it!

Linus Walleij
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