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tty: serial: meson: Implement earlycon support

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Split off the bulk of the existing meson_serial_console_write()
implementation into meson_serial_port_write() for implementing
meson_serial_early_console_write().

Use "meson" as the earlycon driver name, courtesy of Nicolas.

Signed-off-by: Nicolas Saenz Julienne <nicolassaenzj@gmail.com>
Acked-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andreas Färber 2016-03-06 12:21:24 +01:00 committed by Greg Kroah-Hartman
parent 79c9473f11
commit 736d553886
3 changed files with 42 additions and 7 deletions
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6
Documentation/kernel-parameters.txt
View File

@ -1039,6 +1039,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
the driver will use only 32-bit accessors to read/write
the device registers.
meson,<addr>
Start an early, polled-mode console on a meson serial
port at the specified address. The serial port must
already be setup and configured. Options are not yet
supported.
msm_serial,<addr>
Start an early, polled-mode console on an msm serial
port at the specified address. The serial port

1
drivers/tty/serial/Kconfig
View File

@ -213,6 +213,7 @@ config SERIAL_MESON_CONSOLE
bool "Support for console on meson"
depends on SERIAL_MESON=y
select SERIAL_CORE_CONSOLE
select SERIAL_EARLYCON
help
Say Y here if you wish to use a Amlogic MesonX UART as the
system console (the system console is the device which

42
drivers/tty/serial/meson_uart.c
View File

@ -481,18 +481,13 @@ static void meson_console_putchar(struct uart_port *port, int ch)
writel(ch, port->membase + AML_UART_WFIFO);
}
static void meson_serial_console_write(struct console *co, const char *s,
u_int count)
static void meson_serial_port_write(struct uart_port *port, const char *s,
u_int count)
{
struct uart_port *port;
unsigned long flags;
int locked;
u32 val, tmp;
port = meson_ports[co->index];
if (!port)
return;
local_irq_save(flags);
if (port->sysrq) {
locked = 0;
@ -516,6 +511,18 @@ static void meson_serial_console_write(struct console *co, const char *s,
local_irq_restore(flags);
}
static void meson_serial_console_write(struct console *co, const char *s,
u_int count)
{
struct uart_port *port;
port = meson_ports[co->index];
if (!port)
return;
meson_serial_port_write(port, s, count);
}
static int meson_serial_console_setup(struct console *co, char *options)
{
struct uart_port *port;
@ -554,6 +561,27 @@ static int __init meson_serial_console_init(void)
}
console_initcall(meson_serial_console_init);
static void meson_serial_early_console_write(struct console *co,
const char *s,
u_int count)
{
struct earlycon_device *dev = co->data;
meson_serial_port_write(&dev->port, s, count);
}
static int __init
meson_serial_early_console_setup(struct earlycon_device *device, const char *opt)
{
if (!device->port.membase)
return -ENODEV;
device->con->write = meson_serial_early_console_write;
return 0;
}
OF_EARLYCON_DECLARE(meson, "amlogic,meson-uart",
meson_serial_early_console_setup);
#define MESON_SERIAL_CONSOLE (&meson_serial_console)
#else
#define MESON_SERIAL_CONSOLE NULL