837ec2d56c
Allow hardware errors to be caught during early portions of booting, and leave something in the shadow console that people can use to debug their system with (to be printed out by the bootloader on next reset). This enables the hardare error interrupts in head.S, allowing us to find hardware errors when they happen (well, as much as you can with a hardware error) and prints out the trace if it is enabled. This will catch errors (like booting the wrong image on a 533) which previously resulted in a infinite loop/hang, as well as random hardware errors before before setup_arch(). To disable this debug only feature - turn off EARLY_PRINTK. Signed-off-by: Robin Getz <robin.getz@analog.com> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
114 lines
2.7 KiB
C
114 lines
2.7 KiB
C
/*
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* manage a small early shadow of the log buffer which we can pass between the
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* bootloader so early crash messages are communicated properly and easily
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*
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* Copyright 2009 Analog Devices Inc.
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*
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* Enter bugs at http://blackfin.uclinux.org/
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*
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* Licensed under the GPL-2 or later.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/console.h>
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#include <linux/string.h>
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#include <asm/blackfin.h>
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#include <asm/irq_handler.h>
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#include <asm/early_printk.h>
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#define SHADOW_CONSOLE_START (0x500)
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#define SHADOW_CONSOLE_END (0x1000)
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#define SHADOW_CONSOLE_MAGIC_LOC (0x4F0)
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#define SHADOW_CONSOLE_MAGIC (0xDEADBEEF)
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static __initdata char *shadow_console_buffer = (char *)SHADOW_CONSOLE_START;
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__init void early_shadow_write(struct console *con, const char *s,
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unsigned int n)
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{
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unsigned int i;
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/*
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* save 2 bytes for the double null at the end
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* once we fail on a long line, make sure we don't write a short line afterwards
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*/
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if ((shadow_console_buffer + n) <= (char *)(SHADOW_CONSOLE_END - 2)) {
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/* can't use memcpy - it may not be relocated yet */
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for (i = 0; i <= n; i++)
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shadow_console_buffer[i] = s[i];
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shadow_console_buffer += n;
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shadow_console_buffer[0] = 0;
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shadow_console_buffer[1] = 0;
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} else
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shadow_console_buffer = (char *)SHADOW_CONSOLE_END;
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}
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static __initdata struct console early_shadow_console = {
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.name = "early_shadow",
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.write = early_shadow_write,
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.flags = CON_BOOT | CON_PRINTBUFFER,
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.index = -1,
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.device = 0,
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};
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__init int shadow_console_enabled(void)
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{
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return early_shadow_console.flags & CON_ENABLED;
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}
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__init void mark_shadow_error(void)
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{
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int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
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loc[0] = SHADOW_CONSOLE_MAGIC;
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loc[1] = SHADOW_CONSOLE_START;
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}
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__init void enable_shadow_console(void)
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{
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if (!shadow_console_enabled()) {
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register_console(&early_shadow_console);
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/* for now, assume things are going to fail */
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mark_shadow_error();
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}
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}
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static __init int disable_shadow_console(void)
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{
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/*
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* by the time pure_initcall runs, the standard console is enabled,
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* and the early_console is off, so unset the magic numbers
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* unregistering the console is taken care of in common code (See
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* ./kernel/printk:disable_boot_consoles() )
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*/
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int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
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loc[0] = 0;
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return 0;
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}
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pure_initcall(disable_shadow_console);
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/*
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* since we can't use printk, dump numbers (as hex), n = # bits
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*/
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__init void early_shadow_reg(unsigned long reg, unsigned int n)
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{
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/*
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* can't use any "normal" kernel features, since thay
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* may not be relocated to their execute address yet
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*/
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int i;
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char ascii[11] = " 0x";
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n = n / 4;
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reg = reg << ((8 - n) * 4);
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n += 3;
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for (i = 3; i <= n ; i++) {
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ascii[i] = hex_asc_lo(reg >> 28);
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reg <<= 4;
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}
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early_shadow_write(NULL, ascii, n);
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}
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