112 lines
2.7 KiB
C
112 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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* 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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