linux-kernel - Re: [PATCH v2] hte: tegra194: don't access struct gpio

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Date:   Tue, 17 Oct 2023 11:23:30 -0700
From:   Dipen Patel <dipenp@...dia.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andy@...nel.org>
Cc:     timestamp@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v2] hte: tegra194: don't access struct gpio_chip

On 10/13/23 12:23 AM, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> Using struct gpio_chip is not safe as it will disappear if the
> underlying driver is unbound for any reason. Switch to using reference
> counted struct gpio_device and its dedicated accessors.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> Tested-by: Dipen Patel <dipenp@...dia.com>
> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
> [andy: used gpio_device_find_by_fwnode()]
> Reviewed-by: Dipen Patel <dipenp@...dia.com>
> Link: https://lore.kernel.org/r/20231010151709.4104747-3-andriy.shevchenko@linux.intel.com
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
> Dipen,
> 
> Can you retest this patch now rebased on top of current GPIO for-next?
Tested-by: Dipen Patel <dipenp@...dia.com>
> 
> v1 -> v2:
> - rebase on top of current gpio/for-next
> 
>  drivers/hte/hte-tegra194.c | 30 ++++++++++++++++--------------
>  1 file changed, 16 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/hte/hte-tegra194.c b/drivers/hte/hte-tegra194.c
> index 6fe6897047ac..341a134cb7d0 100644
> --- a/drivers/hte/hte-tegra194.c
> +++ b/drivers/hte/hte-tegra194.c
> @@ -132,7 +132,7 @@ struct tegra_hte_soc {
>  	const struct tegra_hte_data *prov_data;
>  	struct tegra_hte_line_data *line_data;
>  	struct hte_chip *chip;
> -	struct gpio_chip *c;
> +	struct gpio_device *gdev;
>  	void __iomem *regs;
>  };
>  
> @@ -418,7 +418,7 @@ static int tegra_hte_line_xlate(struct hte_chip *gc,
>  	 * HTE/GTE namespace.
>  	 */
>  	if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO && !args) {
> -		line_id = desc->attr.line_id - gs->c->base;
> +		line_id = desc->attr.line_id - gpio_device_get_base(gs->gdev);
>  		map = gs->prov_data->map;
>  		map_sz = gs->prov_data->map_sz;
>  	} else if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO && args) {
> @@ -645,7 +645,7 @@ static bool tegra_hte_match_from_linedata(const struct hte_chip *chip,
>  	if (!hte_dev || (hte_dev->prov_data->type != HTE_TEGRA_TYPE_GPIO))
>  		return false;
>  
> -	return hte_dev->c == gpiod_to_chip(hdesc->attr.line_data);
> +	return hte_dev->gdev == gpiod_to_gpio_device(hdesc->attr.line_data);
>  }
>  
>  static const struct of_device_id tegra_hte_of_match[] = {
> @@ -673,14 +673,11 @@ static void tegra_gte_disable(void *data)
>  	tegra_hte_writel(gs, HTE_TECTRL, 0);
>  }
>  
> -static int tegra_get_gpiochip_from_name(struct gpio_chip *chip, void *data)
> +static void tegra_hte_put_gpio_device(void *data)
>  {
> -	return !strcmp(chip->label, data);
> -}
> +	struct gpio_device *gdev = data;
>  
> -static int tegra_gpiochip_match(struct gpio_chip *chip, void *data)
> -{
> -	return chip->fwnode == of_node_to_fwnode(data);
> +	gpio_device_put(gdev);
>  }
>  
>  static int tegra_hte_probe(struct platform_device *pdev)
> @@ -760,8 +757,8 @@ static int tegra_hte_probe(struct platform_device *pdev)
>  
>  		if (of_device_is_compatible(dev->of_node,
>  					    "nvidia,tegra194-gte-aon")) {
> -			hte_dev->c = gpiochip_find("tegra194-gpio-aon",
> -						tegra_get_gpiochip_from_name);
> +			hte_dev->gdev =
> +				gpio_device_find_by_label("tegra194-gpio-aon");
>  		} else {
>  			gpio_ctrl = of_parse_phandle(dev->of_node,
>  						     "nvidia,gpio-controller",
> @@ -772,14 +769,19 @@ static int tegra_hte_probe(struct platform_device *pdev)
>  				return -ENODEV;
>  			}
>  
> -			hte_dev->c = gpiochip_find(gpio_ctrl,
> -						   tegra_gpiochip_match);
> +			hte_dev->gdev =
> +				gpio_device_find_by_fwnode(of_fwnode_handle(gpio_ctrl));
>  			of_node_put(gpio_ctrl);
>  		}
>  
> -		if (!hte_dev->c)
> +		if (!hte_dev->gdev)
>  			return dev_err_probe(dev, -EPROBE_DEFER,
>  					     "wait for gpio controller\n");
> +
> +		ret = devm_add_action_or_reset(dev, tegra_hte_put_gpio_device,
> +					       hte_dev->gdev);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	hte_dev->chip = gc;