linux-kernel - Re: [PATCH 01/30] include: linux: platform_device: more helpers for declaring platform drivers

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Message-ID: <20190626061405.qsqq5na4oactuo6f@pengutronix.de>
Date:   Wed, 26 Jun 2019 08:14:05 +0200
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     "Enrico Weigelt, metux IT consult" <info@...ux.net>
Cc:     linux-kernel@...r.kernel.org, grygorii.strashko@...com,
        mcoquelin.stm32@...il.com, thloh@...era.com, festevam@...il.com,
        linus.walleij@...aro.org, khilman@...nel.org,
        patches@...nsource.cirrus.com, bgolaszewski@...libre.com,
        linux-omap@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-imx@....com, kernel@...gutronix.de, ssantosh@...nel.org,
        linux-tegra@...r.kernel.org, andriy.shevchenko@...ux.intel.com,
        shawnguo@...nel.org, s.hauer@...gutronix.de,
        alexandre.torgue@...com
Subject: Re: [PATCH 01/30] include: linux: platform_device: more helpers for
 declaring platform drivers

Hello,

On Mon, Jun 17, 2019 at 08:40:42PM +0200, Enrico Weigelt, metux IT consult wrote:
> From: Enrico Weigelt <info@...ux.net>
> 
> Add more helper macros for trivial driver init cases, similar to the
> already existing module_platform_driver()+friends - now for those which
> are initialized at other stages. Lots of drivers couldn't use the existing
> macros, as they need to be called at different init stages, eg. subsys,
> postcore, arch.
> 
> This helps to further reduce driver init boilerplate.
> 
> Signed-off-by: Enrico Weigelt <info@...ux.net>
> ---
>  include/linux/platform_device.h | 51 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
> 
> diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
> index beb25f2..5f3a967 100644
> --- a/include/linux/platform_device.h
> +++ b/include/linux/platform_device.h
> @@ -259,6 +259,57 @@ static inline void platform_set_drvdata(struct platform_device *pdev,
>  } \
>  module_exit(__platform_driver##_exit);
>  
> +/* postcore_platform_driver() - Helper macro for drivers that don't do
> + * anything special in module init/exit.  This eliminates a lot of
> + * boilerplate.  Each module may only use this macro once, and
> + * calling it replaces postcore_initcall() and module_exit()
> + */
> +#define postcore_platform_driver(__platform_driver) \
> +static int __init __platform_driver##_init(void) \
> +{ \
> +	return platform_driver_register(&(__platform_driver)); \
> +} \
> +postcore_initcall(__platform_driver##_init); \
> +static void __exit __platform_driver##_exit(void) \
> +{ \
> +	platform_driver_unregister(&(__platform_driver)); \
> +} \
> +module_exit(__platform_driver##_exit);
> +
> +/* subsys_platform_driver() - Helper macro for drivers that don't do
> + * anything special in module init/exit.  This eliminates a lot of
> + * boilerplate.  Each module may only use this macro once, and
> + * calling it replaces subsys_initcall() and module_exit()
> + */
> +#define subsys_platform_driver(__platform_driver) \
> +static int __init __platform_driver##_init(void) \
> +{ \
> +	return platform_driver_register(&(__platform_driver)); \
> +} \
> +subsys_initcall(__platform_driver##_init); \
> +static void __exit __platform_driver##_exit(void) \
> +{ \
> +	platform_driver_unregister(&(__platform_driver)); \
> +} \
> +module_exit(__platform_driver##_exit);

Would it make sense to do something like:

	#define __module_platform_driver(__platform_driver, __initlvl) \
	static int __init __platform_driver##_init(void) \
	{ \
		return platform_driver_register(&(__platform_driver)); \
	} \
	__initlvl ## _initcall(__platform_driver##_init); \
	static void __exit __platform_driver##_exit(void) \
	{ \
		platform_driver_unregister(&(__platform_driver)); \
	} \
	module_exit(__platform_driver##_exit);

	#define postcore_platform_driver(__platform_driver) __module_platform_driver(__platform_driver, postcore)
	#define subsys_platform_driver(__platform_driver) __module_platform_driver(__platform_driver, subsys)
	...

Which would be more compact and makes the difference between these
macros a bit more obvious.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |