Commit 44a4ed42 authored by Tobias Klauser's avatar Tobias Klauser Committed by Ley Foon Tan
Browse files

nios2: enable earlycon support 



Enable generic earlycon support for nios2. This e.g. allows to use a
8250/16650 UART as earlycon.

In order to get the earlycon, we just need to call parse_early_param()
in early_init_devtree() as soon as the device tree is initially scanned.
By adding an stdout-path property to the dts (done in this patch for
10m50_devboard), the earlycon can be used.

In order to provide early printk support, we need to provide a dummy
implementation of early_console_write(), so that
arch/nios2/kernel/early_printk.c can still be compiled if neither
SERIAL_ALTERA_JTAGUART_CONSOLE nor SERIAL_ALTERA_UART_CONSOLE is
selected. As soon as the altera_uart and altera_jtaguart support
earlycon, the entire file can be removed.

Tested-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarTobias Klauser <tklauser@distanz.ch>
Acked-by: default avatarLey Foon Tan <ley.foon.tan@intel.com>
parent 57ac76ed

arch/nios2/Kconfig.debug

+0 −1
Original line number Original line Diff line number Diff line
@@ -18,7 +18,6 @@ config EARLY_PRINTK 
	bool "Activate early kernel debugging"

	bool "Activate early kernel debugging"

	default y

	default y

	select SERIAL_CORE_CONSOLE

	select SERIAL_CORE_CONSOLE

	depends on SERIAL_ALTERA_JTAGUART_CONSOLE || SERIAL_ALTERA_UART_CONSOLE

	help

	help

	  Enable early printk on console

	  Enable early printk on console

	  This is useful for kernel debugging when your machine crashes very

	  This is useful for kernel debugging when your machine crashes very

arch/nios2/boot/dts/10m50_devboard.dts

+2 −1
Original line number Original line Diff line number Diff line
@@ -244,6 +244,7 @@ led_fpga3: fpga3 { 
	};

	};





	chosen {

	chosen {

		bootargs = "debug console=ttyS0,115200";

		bootargs = "debug earlycon console=ttyS0,115200";

		stdout-path = &a_16550_uart_0;

	};

	};

};
 
};

arch/nios2/kernel/early_printk.c

+5 −2
Original line number Original line Diff line number Diff line
@@ -81,8 +81,11 @@ static void early_console_write(struct console *con, const char *s, unsigned n) 
}

}





#else

#else

# error Neither SERIAL_ALTERA_JTAGUART_CONSOLE nor SERIAL_ALTERA_UART_CONSOLE \



selected

static void early_console_write(struct console *con, const char *s, unsigned n)

{

}



#endif

#endif





static struct console early_console_prom = {

static struct console early_console_prom = {

arch/nios2/kernel/setup.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -137,6 +137,8 @@ asmlinkage void __init nios2_boot_init(unsigned r4, unsigned r5, unsigned r6, 
		strncpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);

		strncpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);

#endif

#endif

#endif

#endif



	parse_early_param();

}

}





void __init setup_arch(char **cmdline_p)

void __init setup_arch(char **cmdline_p)