tty: serial: samsung: Enable console as module

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().

Inspired by commit 87a0b9f9 ("tty: serial: meson: enable console as
module").
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211204195757.8600-5-semen.protsenko@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

drivers/tty/serial/samsung_tty.c

@@ -1715,15 +1715,21 @@ s3c24xx_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
 
 static struct console s3c24xx_serial_console;
 
-static int __init s3c24xx_serial_console_init(void)
+static void __init s3c24xx_serial_register_console(void)
 {
 	register_console(&s3c24xx_serial_console);
-	return 0;
 }
-console_initcall(s3c24xx_serial_console_init);
+
+static void s3c24xx_serial_unregister_console(void)
+{
+	if (s3c24xx_serial_console.flags & CON_ENABLED)
+		unregister_console(&s3c24xx_serial_console);
+}
 
 #define S3C24XX_SERIAL_CONSOLE &s3c24xx_serial_console
 #else
+static inline void s3c24xx_serial_register_console(void) { }
+static inline void s3c24xx_serial_unregister_console(void) { }
 #define S3C24XX_SERIAL_CONSOLE NULL
 #endif
 
@@ -2898,7 +2904,29 @@ static struct platform_driver samsung_serial_driver = {
 	},
 };
 
-module_platform_driver(samsung_serial_driver);
+static int __init samsung_serial_init(void)
+{
+	int ret;
+
+	s3c24xx_serial_register_console();
+
+	ret = platform_driver_register(&samsung_serial_driver);
+	if (ret) {
+		s3c24xx_serial_unregister_console();
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit samsung_serial_exit(void)
+{
+	platform_driver_unregister(&samsung_serial_driver);
+	s3c24xx_serial_unregister_console();
+}
+
+module_init(samsung_serial_init);
+module_exit(samsung_serial_exit);
 
 #ifdef CONFIG_SERIAL_SAMSUNG_CONSOLE
 /*