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serial: samsung: Add support for early console

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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 <t.figa@samsung.com>
[mszyprow: added support for command line based initialization,
           fixed comments, added documentation]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tomasz Figa 2015-01-23 14:47:41 +01:00 committed by Greg Kroah-Hartman
parent 8b6ff84c2d
commit b94ba0328d
3 changed files with 116 additions and 0 deletions
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12
Documentation/kernel-parameters.txt
View File

@ -970,6 +970,18 @@ 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

1
drivers/tty/serial/Kconfig
View File

@ -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

103
drivers/tty/serial/samsung.c
View File

@ -2403,6 +2403,109 @@ 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 <ben@simtec.co.uk>");