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Commit 93fd03a8 authored by Catalin Marinas's avatar Catalin Marinas
Browse files

ARM: Add an earlyprintk debug console 



This patch allows an earlyprintk console if CONFIG_DEBUG_LL is enabled,
using the printch asm function.

The patch is based on the original work by Sascha Hauer.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
parent 22763c5c

arch/arm/Kconfig.debug

+8 −0
Original line number Original line Diff line number Diff line
@@ -71,6 +71,14 @@ config DEBUG_LL 
	  in the kernel.  This is helpful if you are debugging code that

	  in the kernel.  This is helpful if you are debugging code that

	  executes before the console is initialized.

	  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

config DEBUG_ICEDCC

	bool "Kernel low-level debugging via EmbeddedICE DCC channel"

	bool "Kernel low-level debugging via EmbeddedICE DCC channel"

	depends on DEBUG_LL

	depends on DEBUG_LL

arch/arm/kernel/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -52,5 +52,6 @@ endif 




head-y			:= head$(MMUEXT).o

head-y			:= head$(MMUEXT).o

obj-$(CONFIG_DEBUG_LL)	+= debug.o

obj-$(CONFIG_DEBUG_LL)	+= debug.o

obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o





extra-y := $(head-y) init_task.o vmlinux.lds
 
extra-y := $(head-y) init_task.o vmlinux.lds

arch/arm/kernel/early_printk.c

0 → 100644
+57 −0
Original line number Original line Diff line number Diff line 
/*

 *  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);