serial: samsung: add support for early console

From: Tomasz Figa <[email protected]>

This patch adds support for early console initialized from device tree and kernel command line to all variants of Samsung serial driver.

Signed-off-by Tomasz Figa <[email protected]>

[mszyprow: added support for command line based initialization,
fixed comments, added documentation]

Signed-off-by Marek Szyprowski <[email protected]>

Reviewed-by Alim Akhtar <[email protected]>

Tested-by Alim Akhtar <[email protected]>

---
 Documentation/kernel-parameters.txt |  12 +++++
 drivers/tty/serial/Kconfig          |   1 +
 drivers/tty/serial/samsung.c        | 103 ++++++++++++++++++++++++++++++++++++
 3 files changed, 116 insertions(+)

Documentation/kernel-parameters.txt +12 -0

index 7dbe5ec9d9cd..24f363108ab3 100644
@@ -961,6 +961,18 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
 		smh	Use ARM semihosting calls for early console.
 
+		s3c2410,<addr>
+		s3c2412,<addr>
+		s3c2440,<addr>
+		s3c6400,<addr>
+		s5pv210,<addr>
+		exynos4210,<addr>
+			Use early console provided by serial driver available
+			on Samsung SoCs, requires selecting proper type and
+			a correct base address of the selected UART port. The
+			serial port must already be setup and configured.
+			Options are not yet supported.
+
 	earlyprintk=	[X86,SH,BLACKFIN,ARM,M68k]
 			earlyprintk=vga
 			earlyprintk=efi

drivers/tty/serial/Kconfig +1 -0

index 649b784081c7..50997be6cf6d 100644
@@ -241,6 +241,7 @@ config SERIAL_SAMSUNG
 	tristate "Samsung SoC serial support"
 	depends on PLAT_SAMSUNG || ARCH_EXYNOS
 	select SERIAL_CORE
+	select SERIAL_EARLYCON
 	help
 	  Support for the on-chip UARTs on the Samsung S3C24XX series CPUs,
 	  providing /dev/ttySAC0, 1 and 2 (note, some machines may not

drivers/tty/serial/samsung.c +103 -0

index c78f43a481ce..8ad453a5d845 100644
@@ -1856,6 +1856,109 @@ static struct platform_driver samsung_serial_driver = {
 
 module_platform_driver(samsung_serial_driver);
 
+/*
+ * Early console.
+ */
+
+struct samsung_early_console_data {
+	u32 txfull_mask;
+};
+
+static void samsung_early_busyuart(struct uart_port *port)
+{
+	while (!(readl(port->membase + S3C2410_UTRSTAT) & S3C2410_UTRSTAT_TXFE))
+		;
+}
+
+static void samsung_early_busyuart_fifo(struct uart_port *port)
+{
+	struct samsung_early_console_data *data = port->private_data;
+
+	while (readl(port->membase + S3C2410_UFSTAT) & data->txfull_mask)
+		;
+}
+
+static void samsung_early_putc(struct uart_port *port, int c)
+{
+	if (readl(port->membase + S3C2410_UFCON) & S3C2410_UFCON_FIFOMODE)
+		samsung_early_busyuart_fifo(port);
+	else
+		samsung_early_busyuart(port);
+
+	writeb(c, port->membase + S3C2410_UTXH);
+}
+
+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, samsung_early_putc);
+}
+
+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;
+}
+
+/* S3C2410 */
+static struct samsung_early_console_data s3c2410_early_console_data = {
+	.txfull_mask = S3C2410_UFSTAT_TXFULL,
+};
+
+static int __init s3c2410_early_console_setup(struct earlycon_device *device,
+					      const char *opt)
+{
+	device->port.private_data = &s3c2410_early_console_data;
+	return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s3c2410, "samsung,s3c2410-uart",
+			s3c2410_early_console_setup);
+EARLYCON_DECLARE(s3c2410, s3c2410_early_console_setup);
+
+/* S3C2412, S3C2440, S3C64xx */
+static struct samsung_early_console_data s3c2440_early_console_data = {
+	.txfull_mask = S3C2440_UFSTAT_TXFULL,
+};
+
+static int __init s3c2440_early_console_setup(struct earlycon_device *device,
+					      const char *opt)
+{
+	device->port.private_data = &s3c2440_early_console_data;
+	return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s3c2412, "samsung,s3c2412-uart",
+			s3c2440_early_console_setup);
+OF_EARLYCON_DECLARE(s3c2440, "samsung,s3c2440-uart",
+			s3c2440_early_console_setup);
+OF_EARLYCON_DECLARE(s3c6400, "samsung,s3c6400-uart",
+			s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c2412, s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c2440, s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c6400, s3c2440_early_console_setup);
+
+/* S5PV210, EXYNOS */
+static struct samsung_early_console_data s5pv210_early_console_data = {
+	.txfull_mask = S5PV210_UFSTAT_TXFULL,
+};
+
+static int __init s5pv210_early_console_setup(struct earlycon_device *device,
+					      const char *opt)
+{
+	device->port.private_data = &s5pv210_early_console_data;
+	return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s5pv210, "samsung,s5pv210-uart",
+			s5pv210_early_console_setup);
+OF_EARLYCON_DECLARE(exynos4210, "samsung,exynos4210-uart",
+			s5pv210_early_console_setup);
+EARLYCON_DECLARE(s5pv210, s5pv210_early_console_setup);
+EARLYCON_DECLARE(exynos4210, s5pv210_early_console_setup);
+
 MODULE_ALIAS("platform:samsung-uart");
 MODULE_DESCRIPTION("Samsung SoC Serial port driver");
 MODULE_AUTHOR("Ben Dooks <[email protected]>");

-----Original Message-----
From: linux-arm-kernel [mailto:linux-arm-kernel- [email protected]] On Behalf Of Marek Szyprowski
Sent: Monday, October 20, 2014 8:28 PM
To: [email protected]; linux-arm- [email protected]
Cc: Tomasz Figa; Kyungmin Park; [email protected]; Alim Akhtar; Marek Szyprowski
Subject: [PATCH v3 0/2] serial: samsung: add support for early console

This patchset adds support for early console defined in device tree. As an example, DTS files for all Exynos4 based machines are updated with the correct value for common chosen/sdtout property.

To get it fully functional on ARM architecture, additional improvements (support for early_ioremap) are needed in early console code.

Best regards
Marek Szyprowski
Samsung R&D Institute Poland

Change log:

v3:
- rebased onto v3.18-rc1
- removed options from documentation (they are not yet supported)

v2: http://www.spinics.net/lists/linux-samsung-soc/msg37278.html
- added support for command line based initialization

v1: http://www.spinics.net/lists/linux-samsung-soc/msg37094.html
- initial version

Tomasz Figa (2):
serial: samsung: Add support for early console
ARM: dts: exynos4: Add stdout-path properties

 Documentation/kernel-parameters.txt             |  12 +++
 arch/arm/boot/dts/exynos4210-origen.dts         |   1 +
 arch/arm/boot/dts/exynos4210-smdkv310.dts       |   1 +
 arch/arm/boot/dts/exynos4210-trats.dts          |   1 +
 arch/arm/boot/dts/exynos4210-universal_c210.dts |   1 +
 arch/arm/boot/dts/exynos4412-odroid-common.dtsi |   4 +
 arch/arm/boot/dts/exynos4412-origen.dts         |   1 +
 arch/arm/boot/dts/exynos4412-smdk4412.dts       |   1 +
 arch/arm/boot/dts/exynos4412-tiny4412.dts       |   4 +
 arch/arm/boot/dts/exynos4412-trats2.dts         |   1 +
 drivers/tty/serial/Kconfig                      |   1 +
 drivers/tty/serial/samsung.c                    | 103
++++++++++++++++++++++++
 12 files changed, 131 insertions(+)

--
1.9.2

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