linux-kernel - Re: [PATCH v3] gpio: sim: don't fiddle with GPIOLIB private members

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Message-ID: <ZPcZfd5UtzMmIUvm@smile.fi.intel.com>
Date:   Tue, 5 Sep 2023 15:05:17 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Kent Gibson <warthog618@...il.com>, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v3] gpio: sim: don't fiddle with GPIOLIB private members

On Tue, Sep 05, 2023 at 10:24:13AM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> We access internals of struct gpio_device and struct gpio_desc because
> it's easier but it can actually be avoided and we're working towards a
> better encapsulation of GPIO data structures across the kernel so let's
> start at home.
> 
> Instead of checking gpio_desc flags, let's just track the requests of
> GPIOs in the driver. We also already store the information about
> direction of simulated lines.
> 
> For kobjects needed by sysfs callbacks: we can iterate over the children
> devices of the top-level platform device and compare their fwnodes
> against the one passed to the init function from probe.
> 
> While at it: fix one line break and remove the untrue part about
> configfs callbacks using dev_get_drvdata() from a comment.

...

> v2 -> v3:
> - don't use fwnode internal fields, instead: iterate over the platform
>   device's children and locate the GPIO device

Thank you!

...

> @@ -181,7 +178,7 @@ static int gpio_sim_get_direction(struct gpio_chip *gc, unsigned int offset)

>  static int gpio_sim_set_config(struct gpio_chip *gc,
> -				  unsigned int offset, unsigned long config)
> +			       unsigned int offset, unsigned long config)

Looking at other prototypes, it can be

static int gpio_sim_set_config(struct gpio_chip *gc, unsigned int offset,
			       unsigned long config)

...

> +static int gpio_sim_chip_set_device(struct device *dev, void *data)
> +{
> +	struct gpio_sim_chip *chip = data;

> +	if (chip->swnode == dev->fwnode) {

Please do not dereference fwnode from the struct device, we have an API!
device_match_fwnode()

> +		chip->dev = dev;
> +		return 1;
> +	}
> +
> +	return 0;
> +}

...

> +	chip->swnode = swnode;
> +	ret = device_for_each_child(dev, chip, gpio_sim_chip_set_device);
> +	if (!ret)
> +		return -ENODEV;

Can bus_find_device_by_fwnode() be used here?

-- 
With Best Regards,
Andy Shevchenko