linux-kernel - Re: [PATCH 5/8] tty: serial: samsung: Enable console as module

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Date:   Mon, 29 Nov 2021 09:52:15 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Sam Protsenko <semen.protsenko@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jaewon Kim <jaewon02.kim@...sung.com>,
        Chanho Park <chanho61.park@...sung.com>,
        David Virag <virag.david003@...il.com>,
        Youngmin Nam <youngmin.nam@...sung.com>,
        devicetree@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-i2c@...r.kernel.org
Subject: Re: [PATCH 5/8] tty: serial: samsung: Enable console as module

On 27/11/2021 23:32, Sam Protsenko wrote:
> Enable serial driver to be built as a module. To do so, init the console
> support on driver/module load instead of using console_initcall().
> 
> This is needed for proper support of USIv2 driver (which can be built as
> a module, which in turn makes SERIAL_SAMSUNG be a module too). It also
> might be useful for Android GKI modularization efforts.
> 
> Inspired by commit 87a0b9f98ac5 ("tty: serial: meson: enable console as
> module").
> 
> Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>
> ---
>  drivers/tty/serial/Kconfig       |  2 +-
>  drivers/tty/serial/samsung_tty.c | 21 +++++++++++++++++++--
>  2 files changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index fc543ac97c13..0e5ccb25bdb1 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -263,7 +263,7 @@ config SERIAL_SAMSUNG_UARTS
>  
>  config SERIAL_SAMSUNG_CONSOLE
>  	bool "Support for console on Samsung SoC serial port"
> -	depends on SERIAL_SAMSUNG=y
> +	depends on SERIAL_SAMSUNG
>  	select SERIAL_CORE_CONSOLE
>  	select SERIAL_EARLYCON
>  	help
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index f986a9253dc8..92a63e9392ed 100644
> --- a/drivers/tty/serial/samsung_tty.c
> +++ b/drivers/tty/serial/samsung_tty.c
> @@ -1720,10 +1720,10 @@ static int __init s3c24xx_serial_console_init(void)
>  	register_console(&s3c24xx_serial_console);
>  	return 0;
>  }
> -console_initcall(s3c24xx_serial_console_init);
>  
>  #define S3C24XX_SERIAL_CONSOLE &s3c24xx_serial_console
>  #else
> +static inline int s3c24xx_serial_console_init(void) { return 0; }
>  #define S3C24XX_SERIAL_CONSOLE NULL
>  #endif
>  
> @@ -2898,7 +2898,24 @@ static struct platform_driver samsung_serial_driver = {
>  	},
>  };
>  
> -module_platform_driver(samsung_serial_driver);
> +static int __init samsung_serial_init(void)
> +{
> +	int ret;
> +
> +	ret = s3c24xx_serial_console_init();
> +	if (ret)
> +		return ret;

This will trigger warns on module re-loading, won't it? Either suppress
unbind or cleanup in module exit.

> +
> +	return platform_driver_register(&samsung_serial_driver);
> +}
> +
> +static void __exit samsung_serial_exit(void)
> +{
> +	platform_driver_unregister(&samsung_serial_driver);
> +}
> +
> +module_init(samsung_serial_init);
> +module_exit(samsung_serial_exit);
>  
>  #ifdef CONFIG_SERIAL_SAMSUNG_CONSOLE
>  /*
> 


Best regards,
Krzysztof