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/*
* 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.
*
* 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;
__init void early_shadow_write(struct console *con, const char *s,
unsigned int n)
{
unsigned int i;
/*
* 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)) {
/* can't use memcpy - it may not be relocated yet */
for (i = 0; i <= n; i++)
shadow_console_buffer[i] = s[i];
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 int shadow_console_enabled(void)
{
return early_shadow_console.flags & CON_ENABLED;
}
__init void mark_shadow_error(void)
{
int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
loc[0] = SHADOW_CONSOLE_MAGIC;
loc[1] = SHADOW_CONSOLE_START;
}
__init void enable_shadow_console(void)
{
if (!shadow_console_enabled()) {
register_console(&early_shadow_console);
/* for now, assume things are going to fail */
mark_shadow_error();
}
}
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] = 0;
return 0;
}
pure_initcall(disable_shadow_console);
/*
* since we can't use printk, dump numbers (as hex), n = # bits
*/
__init void early_shadow_reg(unsigned long reg, unsigned int n)
{
/*
* can't use any "normal" kernel features, since thay
* may not be relocated to their execute address yet
*/
int i;
char ascii[11] = " 0x";
n = n / 4;
reg = reg << ((8 - n) * 4);
n += 3;
for (i = 3; i <= n ; i++) {
ascii[i] = hex_asc_lo(reg >> 28);
reg <<= 4;
}
early_shadow_write(NULL, ascii, n);
}
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