nios2: enable earlycon support (44a4ed42) · Commits · 戴 / test

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:

Guenter Roeck <linux@roeck-us.net> Signed-off-by:

Tobias Klauser <tklauser@distanz.ch> Acked-by:

Ley Foon Tan <ley.foon.tan@intel.com>

arch/nios2/Kconfig.debug

+0 −1

Original line number	Diff line number	Diff line
		@@ -18,7 +18,6 @@ config EARLY_PRINTK
		bool "Activate early kernel debugging"
		default y
		select SERIAL_CORE_CONSOLE
		depends on SERIAL_ALTERA_JTAGUART_CONSOLE \|\| SERIAL_ALTERA_UART_CONSOLE
		help
		Enable early printk on console
		This is useful for kernel debugging when your machine crashes very

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

+2 −1

Original line number	Diff line number	Diff line
		@@ -244,6 +244,7 @@
		};

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

		#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

		static struct console early_console_prom = {

arch/nios2/kernel/setup.c

+2 −0

Original line number	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);
		#endif
		#endif

		parse_early_param();
		}

		void __init setup_arch(char **cmdline_p)

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