113 lines
3.0 KiB
Diff
113 lines
3.0 KiB
Diff
From: Catalin Marinas <catalin.marinas@arm.com>
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Date: Wed, 9 Dec 2009 10:02:18 +0000 (+0000)
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Subject: ARM: Add an earlyprintk debug console
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X-Git-Tag: v2.6.33-rc1~286^2~4
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=93fd03a8c6728b58879f8af20ffd55d9c32a778b
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ARM: Add an earlyprintk debug console
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This patch allows an earlyprintk console if CONFIG_DEBUG_LL is enabled,
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using the printch asm function.
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The patch is based on the original work by Sascha Hauer.
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Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Cc: Sascha Hauer <s.hauer@pengutronix.de>
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Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
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Acked-by: Pavel Machek <pavel@ucw.cz>
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---
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diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
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index 1a6f70e..feb7b11 100644
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--- a/arch/arm/Kconfig.debug
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+++ b/arch/arm/Kconfig.debug
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@@ -71,6 +71,14 @@ config DEBUG_LL
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in the kernel. This is helpful if you are debugging code that
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executes before the console is initialized.
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+config EARLY_PRINTK
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+ bool "Early printk"
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+ depends on DEBUG_LL
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+ help
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+ Say Y here if you want to have an early console using the
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+ kernel low-level debugging functions. Add earlyprintk to your
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+ kernel parameters to enable this console.
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+
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config DEBUG_ICEDCC
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bool "Kernel low-level debugging via EmbeddedICE DCC channel"
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depends on DEBUG_LL
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diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
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index 79087dd..d0e40b7 100644
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--- a/arch/arm/kernel/Makefile
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+++ b/arch/arm/kernel/Makefile
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@@ -52,5 +52,6 @@ endif
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head-y := head$(MMUEXT).o
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obj-$(CONFIG_DEBUG_LL) += debug.o
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+obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
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extra-y := $(head-y) init_task.o vmlinux.lds
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diff --git a/arch/arm/kernel/early_printk.c b/arch/arm/kernel/early_printk.c
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new file mode 100644
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index 0000000..85aa2b2
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--- /dev/null
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+++ b/arch/arm/kernel/early_printk.c
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@@ -0,0 +1,57 @@
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+/*
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+ * linux/arch/arm/kernel/early_printk.c
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+ *
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+ * Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+
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+#include <linux/kernel.h>
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+#include <linux/console.h>
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+#include <linux/init.h>
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+
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+extern void printch(int);
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+
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+static void early_write(const char *s, unsigned n)
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+{
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+ while (n-- > 0) {
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+ if (*s == '\n')
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+ printch('\r');
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+ printch(*s);
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+ s++;
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+ }
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+}
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+
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+static void early_console_write(struct console *con, const char *s, unsigned n)
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+{
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+ early_write(s, n);
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+}
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+
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+static struct console early_console = {
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+ .name = "earlycon",
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+ .write = early_console_write,
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+ .flags = CON_PRINTBUFFER | CON_BOOT,
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+ .index = -1,
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+};
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+
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+asmlinkage void early_printk(const char *fmt, ...)
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+{
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+ char buf[512];
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+ int n;
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+ va_list ap;
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+
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+ va_start(ap, fmt);
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+ n = vscnprintf(buf, sizeof(buf), fmt, ap);
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+ early_write(buf, n);
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+ va_end(ap);
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+}
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+
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+static int __init setup_early_printk(char *buf)
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+{
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+ register_console(&early_console);
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+ return 0;
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+}
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+
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+early_param("earlyprintk", setup_early_printk);
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