diff options
| -rw-r--r-- | arch/arm/Kconfig.debug | 8 | ||||
| -rw-r--r-- | arch/arm/kernel/Makefile | 1 | ||||
| -rw-r--r-- | arch/arm/kernel/early_printk.c | 57 |
3 files changed, 66 insertions, 0 deletions
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index 1a6f70e5292..feb7b11ed5b 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -71,6 +71,14 @@ config DEBUG_LL in the kernel. This is helpful if you are debugging code that executes before the console is initialized. +config EARLY_PRINTK + bool "Early printk" + depends on DEBUG_LL + help + Say Y here if you want to have an early console using the + kernel low-level debugging functions. Add earlyprintk to your + kernel parameters to enable this console. + config DEBUG_ICEDCC bool "Kernel low-level debugging via EmbeddedICE DCC channel" depends on DEBUG_LL diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 79087dd6d86..d0e40b7d5f4 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -52,5 +52,6 @@ endif head-y := head$(MMUEXT).o obj-$(CONFIG_DEBUG_LL) += debug.o +obj-$(CONFIG_EARLY_PRINTK) += early_printk.o extra-y := $(head-y) init_task.o vmlinux.lds diff --git a/arch/arm/kernel/early_printk.c b/arch/arm/kernel/early_printk.c new file mode 100644 index 00000000000..85aa2b29269 --- /dev/null +++ b/arch/arm/kernel/early_printk.c @@ -0,0 +1,57 @@ +/* + * linux/arch/arm/kernel/early_printk.c + * + * Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/console.h> +#include <linux/init.h> + +extern void printch(int); + +static void early_write(const char *s, unsigned n) +{ + while (n-- > 0) { + if (*s == '\n') + printch('\r'); + printch(*s); + s++; + } +} + +static void early_console_write(struct console *con, const char *s, unsigned n) +{ + early_write(s, n); +} + +static struct console early_console = { + .name = "earlycon", + .write = early_console_write, + .flags = CON_PRINTBUFFER | CON_BOOT, + .index = -1, +}; + +asmlinkage void early_printk(const char *fmt, ...) +{ + char buf[512]; + int n; + va_list ap; + + va_start(ap, fmt); + n = vscnprintf(buf, sizeof(buf), fmt, ap); + early_write(buf, n); + va_end(ap); +} + +static int __init setup_early_printk(char *buf) +{ + register_console(&early_console); + return 0; +} + +early_param("earlyprintk", setup_early_printk); |