linux-kernel - Re: [PATCH v3 06/10] gpio: sysfs: don't use driver data in sysfs callbacks for line attributes

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Message-ID: <aGKQ3m87REse0abU@smile.fi.intel.com>
Date: Mon, 30 Jun 2025 16:27:58 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Ahmad Fatoum <a.fatoum@...gutronix.de>,
	Kent Gibson <warthog618@...il.com>,
	Jan Lübbe <jlu@...gutronix.de>,
	Marek Vasut <marex@...x.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v3 06/10] gpio: sysfs: don't use driver data in sysfs
 callbacks for line attributes

On Mon, Jun 30, 2025 at 02:37:13PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> Currently each exported GPIO is represented in sysfs as a separate class
> device. This allows us to simply use dev_get_drvdata() to retrieve the
> pointer passed to device_create_with_groups() from sysfs ops callbacks.
> 
> However, we're preparing to add a parallel set of per-line sysfs
> attributes that will live inside the associated gpiochip group. They are
> not registered as class devices and so have the parent device passed as
> argument to their callbacks (the GPIO chip class device).
> 
> Put the attribute structs inside the GPIO descriptor data and
> dereference the relevant ones using container_of() in the callbacks.
> This way, we'll be able to reuse the same code for both the legacy and
> new GPIO attributes.

...

> -	struct gpiod_data *data = dev_get_drvdata(dev);
> +	struct gpiod_data *data = container_of(attr, struct gpiod_data,
> +					       dir_attr);

> -	struct gpiod_data *data = dev_get_drvdata(dev);
> +	struct gpiod_data *data = container_of(attr, struct gpiod_data,
> +					       dir_attr);

I still think that bunch of definitions to wrap contaner_of():s will help.
Note, two of them you are using even in the code below, besides the attribute
show()/store() cases.

...

> +	if (strcmp(attr->name, "direction") == 0) {
> +		data = container_of(dev_attr, struct gpiod_data, dir_attr);
> +
> +		if (!data->direction_can_change)
>  			mode = 0;

		data = dir_attr_to_gpiod_data(dev_attr);
		if (!data->direction_can_change)
			mode = 0;

> +	} else if (strcmp(attr->name, "edge") == 0) {

> +		data = container_of(dev_attr, struct gpiod_data, edge_attr);
> +
> +		if (gpiod_to_irq(data->desc) < 0)
>  			mode = 0;

In the similar way:

		data = edge_attr_to_gpiod_data(dev_attr);
		if (gpiod_to_irq(data->desc) < 0)
			mode = 0;

> +		if (!data->direction_can_change &&
> +		    test_bit(FLAG_IS_OUT, &data->desc->flags))
>  			mode = 0;
>  	}

-- 
With Best Regards,
Andy Shevchenko