[PATCH] tty/serial: samsung: Add earlycon support

[Alim Akhtar]

Add earlycon support for the samsung serial port. This allows enabling
the samsung serial port for console when early_params are parse and processed.

Signed-off-by: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
---
 Documentation/kernel-parameters.txt |    6 ++++++
 drivers/tty/serial/Kconfig          |    1 +
 drivers/tty/serial/samsung.c        |   17 +++++++++++++++++
 3 files changed, 24 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 5ae8608..e01c0e5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -936,6 +936,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			must already be setup and configured. Options are not
 			yet supported.
 
+		samsung,<addr>
+			Start an early, polled-mode console on a samsung serial
+			port at the specified address. The samsung serial port
+			must already be setup and configured. Options are not
+			yet supported.
+
 		smh	Use ARM semihosting calls for early console.
 
 	earlyprintk=	[X86,SH,BLACKFIN,ARM,M68k]
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 249e340..9d42ac8 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -257,6 +257,7 @@ config SERIAL_SAMSUNG_CONSOLE
 	bool "Support for console on Samsung SoC serial port"
 	depends on SERIAL_SAMSUNG=y
 	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
 	help
 	  Allow selection of the S3C24XX on-board serial ports for use as
 	  an virtual console.
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index c78f43a..f32e9c8 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -917,6 +917,7 @@ s3c24xx_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
 #ifdef CONFIG_SERIAL_SAMSUNG_CONSOLE
 
 static struct console s3c24xx_serial_console;
+static void s3c24xx_serial_console_putchar(struct uart_port *port, int ch);
 
 static int __init s3c24xx_serial_console_init(void)
 {
@@ -926,6 +927,22 @@ static int __init s3c24xx_serial_console_init(void)
 console_initcall(s3c24xx_serial_console_init);
 
 #define S3C24XX_SERIAL_CONSOLE &s3c24xx_serial_console
+static void samsung_early_write(struct console *con, const char *s, unsigned n)
+{
+	struct earlycon_device *dev = con->data;
+
+	uart_console_write(&dev->port, s, n, s3c24xx_serial_console_putchar);
+}
+
+static int __init samsung_early_console_setup(struct earlycon_device *device,
+					      const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+	device->con->write = samsung_early_write;
+	return 0;
+}
+EARLYCON_DECLARE(samsung, samsung_early_console_setup);
 #else
 #define S3C24XX_SERIAL_CONSOLE NULL
 #endif
-- 
1.7.10.4

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