linux-kernel - [PATCH v2 4/5] tty: serial: samsung: Enable console as module

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Date:   Tue, 30 Nov 2021 04:27:39 +0200
From:   Sam Protsenko <semen.protsenko@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jiri Slaby <jirislaby@...nel.org>,
        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-serial@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org
Subject: [PATCH v2 4/5] 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().

This is needed for proper support of USI 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>
---
Changes in v2:
  - Added error path handling in samsung_serial_init()
  - Added console unregister in samsung_serial_exit()

 drivers/tty/serial/Kconfig       |  2 +-
 drivers/tty/serial/samsung_tty.c | 36 ++++++++++++++++++++++++++++----
 2 files changed, 33 insertions(+), 5 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..61ccb359620a 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/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
 /*
-- 
2.30.2