linux-kernel - Re: [PATCH v2] gpio: Allow setting gpio device id via device tree alias

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Date:   Mon, 28 Mar 2022 01:07:27 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Bough Chen <haibo.chen@....com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH v2] gpio: Allow setting gpio device id via device tree alias

On Tue, Mar 22, 2022 at 11:16 AM Bough Chen <haibo.chen@....com> wrote:

> For users, usually, they will open /dev/gpiochipx to handle gpio related option.

That makes sense, it is intuitive in a way.

> By the way, how can user get the labels and device names of GPIO chips?

The way to get metadata for any /dev/* device such as topology on
buses is through sysfs.

It is also possible to get labels for all gpiochips by iterating over them.

The most user-friendly thing to do is however to make use of libgpiod
and associated example tools such as gpiodetect:
https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/about/

Yours,
Linus Walleij