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serial: mps2-uart: add support for early console

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This adds support early console for MPS2 UART which can be enabled via
earlycon=mps2,0x40004000

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vladimir Murzin 2016-04-25 09:47:48 +01:00 committed by Greg Kroah-Hartman
parent 041f031def
commit bd8d257fa3
2 changed files with 29 additions and 0 deletions
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1
drivers/tty/serial/Kconfig
View File

@ -1452,6 +1452,7 @@ config SERIAL_MPS2_UART_CONSOLE
bool "MPS2 UART console support"
depends on SERIAL_MPS2_UART
select SERIAL_CORE_CONSOLE
select SERIAL_EARLYCON
config SERIAL_MPS2_UART
bool "MPS2 UART port"

28
drivers/tty/serial/mps2-uart.c
View File

@ -450,6 +450,34 @@ static struct console mps2_uart_console = {
#define MPS2_SERIAL_CONSOLE (&mps2_uart_console)
static void mps2_early_putchar(struct uart_port *port, int ch)
{
while (readb(port->membase + UARTn_STATE) & UARTn_STATE_TX_FULL)
cpu_relax();
writeb((unsigned char)ch, port->membase + UARTn_DATA);
}
static void mps2_early_write(struct console *con, const char *s, unsigned int n)
{
struct earlycon_device *dev = con->data;
uart_console_write(&dev->port, s, n, mps2_early_putchar);
}
static int __init mps2_early_console_setup(struct earlycon_device *device,
const char *opt)
{
if (!device->port.membase)
return -ENODEV;
device->con->write = mps2_early_write;
return 0;
}
OF_EARLYCON_DECLARE(mps2, "arm,mps2-uart", mps2_early_console_setup);
#else
#define MPS2_SERIAL_CONSOLE NULL
#endif