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Commit 3f871fea authored by Robin Getz's avatar Robin Getz Committed by Mike Frysinger
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Blackfin: add an early shadow console 



Add a memory based shadow console to keep a copy of the printk buffer in a
location which can be found externally.  This allows bootloaders to locate
and utilize the log buffer in case of silent (early/resume/etc...) crashes.

Signed-off-by: default avatarRobin Getz <robin.getz@analog.com>
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
parent 53e18df7

arch/blackfin/include/asm/early_printk.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -23,6 +23,8 @@ 




#ifdef CONFIG_EARLY_PRINTK

#ifdef CONFIG_EARLY_PRINTK

extern int setup_early_printk(char *);

extern int setup_early_printk(char *);

extern void enable_shadow_console(void);

#else

#else

#define setup_early_printk(fmt) do { } while (0)

#define setup_early_printk(fmt) do { } while (0)

#define enable_shadow_console(fmt)  do { } while (0)

#endif /* CONFIG_EARLY_PRINTK */
 
#endif /* CONFIG_EARLY_PRINTK */

arch/blackfin/kernel/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -26,6 +26,7 @@ obj-$(CONFIG_MODULES) += module.o 
obj-$(CONFIG_KGDB)                   += kgdb.o

obj-$(CONFIG_KGDB)                   += kgdb.o

obj-$(CONFIG_KGDB_TESTS)             += kgdb_test.o

obj-$(CONFIG_KGDB_TESTS)             += kgdb_test.o

obj-$(CONFIG_EARLY_PRINTK)           += early_printk.o

obj-$(CONFIG_EARLY_PRINTK)           += early_printk.o

obj-$(CONFIG_EARLY_PRINTK)           += shadow_console.o

obj-$(CONFIG_STACKTRACE)             += stacktrace.o

obj-$(CONFIG_STACKTRACE)             += stacktrace.o





# the kgdb test puts code into L2 and without linker

# the kgdb test puts code into L2 and without linker

arch/blackfin/kernel/setup.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -810,6 +810,8 @@ void __init setup_arch(char **cmdline_p) 
{

{

	unsigned long sclk, cclk;

	unsigned long sclk, cclk;





	enable_shadow_console();



	/* Check to make sure we are running on the right processor */

	/* Check to make sure we are running on the right processor */

	if (unlikely(CPUID != bfin_cpuid()))

	if (unlikely(CPUID != bfin_cpuid()))

		printk(KERN_ERR "ERROR: Not running on ADSP-%s: unknown CPUID 0x%04x Rev 0.%d\n",

		printk(KERN_ERR "ERROR: Not running on ADSP-%s: unknown CPUID 0x%04x Rev 0.%d\n",

arch/blackfin/kernel/shadow_console.c

0 → 100644
+78 −0
Original line number Original line Diff line number Diff line 
/*

 * manage a small early shadow of the log buffer which we can pass between the

 * bootloader so early crash messages are communicated properly and easily

 *

 * Copyright 2009 Analog Devices Inc.

 *

 * Enter bugs at http://blackfin.uclinux.org/

 *

 * Licensed under the GPL-2 or later.

 */



#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/console.h>

#include <linux/string.h>

#include <asm/blackfin.h>

#include <asm/irq_handler.h>

#include <asm/early_printk.h>



#define SHADOW_CONSOLE_START		(0x500)

#define SHADOW_CONSOLE_END		(0x1000)

#define SHADOW_CONSOLE_MAGIC_LOC	(0x4F0)

#define SHADOW_CONSOLE_MAGIC		(0xDEADBEEF)



static __initdata char *shadow_console_buffer = (char *)SHADOW_CONSOLE_START;



static __init void early_shadow_write(struct console *con, const char *s,

				unsigned int n)

{

	/*

	 * save 2 bytes for the double null at the end

	 * once we fail on a long line, make sure we don't write a short line afterwards

	 */

	if ((shadow_console_buffer + n) <= (char *)(SHADOW_CONSOLE_END - 2)) {

		memcpy(shadow_console_buffer, s, n);

		shadow_console_buffer += n;

		shadow_console_buffer[0] = 0;

		shadow_console_buffer[1] = 0;

	} else

		shadow_console_buffer = (char *)SHADOW_CONSOLE_END;

}



static __initdata struct console early_shadow_console = {

	.name = "early_shadow",

	.write = early_shadow_write,

	.flags = CON_BOOT | CON_PRINTBUFFER,

	.index = -1,

	.device = 0,

};



__init void enable_shadow_console(void)

{

	int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;



	if (!(early_shadow_console.flags & CON_ENABLED)) {

		register_console(&early_shadow_console);

		/* for now, assume things are going to fail */

		*loc = SHADOW_CONSOLE_MAGIC;

		loc++;

		*loc = SHADOW_CONSOLE_START;

	}

}



static __init int disable_shadow_console(void)

{

	/*

	 * by the time pure_initcall runs, the standard console is enabled,

	 * and the early_console is off, so unset the magic numbers

	 * unregistering the console is taken care of in common code (See

	 * ./kernel/printk:disable_boot_consoles() )

	 */

	int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;



	*loc = 0;



	return 0;

}

pure_initcall(disable_shadow_console);