2 * manage a small early shadow of the log buffer which we can pass between the
3 * bootloader so early crash messages are communicated properly and easily
5 * Copyright 2009 Analog Devices Inc.
7 * Enter bugs at http://blackfin.uclinux.org/
9 * Licensed under the GPL-2 or later.
12 #include <linux/kernel.h>
13 #include <linux/init.h>
14 #include <linux/console.h>
15 #include <linux/string.h>
16 #include <asm/blackfin.h>
17 #include <asm/irq_handler.h>
18 #include <asm/early_printk.h>
20 #define SHADOW_CONSOLE_START (0x500)
21 #define SHADOW_CONSOLE_END (0x1000)
22 #define SHADOW_CONSOLE_MAGIC_LOC (0x4F0)
23 #define SHADOW_CONSOLE_MAGIC (0xDEADBEEF)
25 static __initdata char *shadow_console_buffer = (char *)SHADOW_CONSOLE_START;
27 __init void early_shadow_write(struct console *con, const char *s,
32 * save 2 bytes for the double null at the end
33 * once we fail on a long line, make sure we don't write a short line afterwards
35 if ((shadow_console_buffer + n) <= (char *)(SHADOW_CONSOLE_END - 2)) {
36 /* can't use memcpy - it may not be relocated yet */
37 for (i = 0; i <= n; i++)
38 shadow_console_buffer[i] = s[i];
39 shadow_console_buffer += n;
40 shadow_console_buffer[0] = 0;
41 shadow_console_buffer[1] = 0;
43 shadow_console_buffer = (char *)SHADOW_CONSOLE_END;
46 static __initdata struct console early_shadow_console = {
47 .name = "early_shadow",
48 .write = early_shadow_write,
49 .flags = CON_BOOT | CON_PRINTBUFFER,
54 __init int shadow_console_enabled(void)
56 return early_shadow_console.flags & CON_ENABLED;
59 __init void mark_shadow_error(void)
61 int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
62 loc[0] = SHADOW_CONSOLE_MAGIC;
63 loc[1] = SHADOW_CONSOLE_START;
66 __init void enable_shadow_console(void)
68 if (!shadow_console_enabled()) {
69 register_console(&early_shadow_console);
70 /* for now, assume things are going to fail */
75 static __init int disable_shadow_console(void)
78 * by the time pure_initcall runs, the standard console is enabled,
79 * and the early_console is off, so unset the magic numbers
80 * unregistering the console is taken care of in common code (See
81 * ./kernel/printk:disable_boot_consoles() )
83 int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
89 pure_initcall(disable_shadow_console);
92 * since we can't use printk, dump numbers (as hex), n = # bits
94 __init void early_shadow_reg(unsigned long reg, unsigned int n)
97 * can't use any "normal" kernel features, since thay
98 * may not be relocated to their execute address yet
101 char ascii[11] = " 0x";
104 reg = reg << ((8 - n) * 4);
107 for (i = 3; i <= n ; i++) {
108 ascii[i] = hex_asc_lo(reg >> 28);
111 early_shadow_write(NULL, ascii, n);