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serial: altera_uart: add earlycon support 

Nios2 currently uses its own early printk implementation, rather than
using unified earlycon support to show boot messages on altera_uart.

Add earlycon support to altera_uart so that other archs may use it.
Also, this (together with the corresponding patch for altera_jtaguart)
will allow the early printk implementation in arch/nios2 to be removed
in a future patch.

Cc: Ley Foon Tan <lftan@altera.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tobias Klauser 2017-03-22 13:50:13 +01:00 committed by Greg Kroah-Hartman
parent a4199f5eb8
commit 4d9d7d896d
2 changed files with 33 additions and 0 deletions
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1
drivers/tty/serial/Kconfig
View File

@ -1392,6 +1392,7 @@ config SERIAL_ALTERA_UART_CONSOLE
bool "Altera UART console support"
depends on SERIAL_ALTERA_UART=y
select SERIAL_CORE_CONSOLE
select SERIAL_EARLYCON
help
Enable a Altera UART port to be the system console.

32
drivers/tty/serial/altera_uart.c
View File

@ -489,6 +489,38 @@ console_initcall(altera_uart_console_init);
#define ALTERA_UART_CONSOLE (&altera_uart_console)
static void altera_uart_earlycon_write(struct console *co, const char *s,
unsigned int count)
{
struct earlycon_device *dev = co->data;
uart_console_write(&dev->port, s, count, altera_uart_console_putc);
}
static int __init altera_uart_earlycon_setup(struct earlycon_device *dev,
const char *options)
{
struct uart_port *port = &dev->port;
if (!port->membase)
return -ENODEV;
/* Enable RX interrupts now */
writel(ALTERA_UART_CONTROL_RRDY_MSK,
port->membase + ALTERA_UART_CONTROL_REG);
if (dev->baud) {
unsigned int baudclk = port->uartclk / dev->baud;
writel(baudclk, port->membase + ALTERA_UART_DIVISOR_REG);
}
dev->con->write = altera_uart_earlycon_write;
return 0;
}
OF_EARLYCON_DECLARE(uart, "altr,uart-1.0", altera_uart_earlycon_setup);
#else
#define ALTERA_UART_CONSOLE NULL