1 /*
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
4 *
5 * Copyright 2009 Analog Devices Inc.
6 *
7 * Licensed under the GPL-2 or later.
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/init.h>
12 #include <linux/console.h>
13 #include <linux/string.h>
14 #include <asm/blackfin.h>
15 #include <asm/irq_handler.h>
16 #include <asm/early_printk.h>
17
18 #define SHADOW_CONSOLE_START (CONFIG_PHY_RAM_BASE_ADDRESS + 0x500)
19 #define SHADOW_CONSOLE_END (CONFIG_PHY_RAM_BASE_ADDRESS + 0x1000)
20 #define SHADOW_CONSOLE_MAGIC_LOC (CONFIG_PHY_RAM_BASE_ADDRESS + 0x4F0)
21 #define SHADOW_CONSOLE_MAGIC (0xDEADBEEF)
22
23 static __initdata char *shadow_console_buffer = (char *)SHADOW_CONSOLE_START;
24
early_shadow_write(struct console * con,const char * s,unsigned int n)25 __init void early_shadow_write(struct console *con, const char *s,
26 unsigned int n)
27 {
28 unsigned int i;
29 /*
30 * save 2 bytes for the double null at the end
31 * once we fail on a long line, make sure we don't write a short line afterwards
32 */
33 if ((shadow_console_buffer + n) <= (char *)(SHADOW_CONSOLE_END - 2)) {
34 /* can't use memcpy - it may not be relocated yet */
35 for (i = 0; i <= n; i++)
36 shadow_console_buffer[i] = s[i];
37 shadow_console_buffer += n;
38 shadow_console_buffer[0] = 0;
39 shadow_console_buffer[1] = 0;
40 } else
41 shadow_console_buffer = (char *)SHADOW_CONSOLE_END;
42 }
43
44 static __initdata struct console early_shadow_console = {
45 .name = "early_shadow",
46 .write = early_shadow_write,
47 .flags = CON_BOOT | CON_PRINTBUFFER,
48 .index = -1,
49 .device = 0,
50 };
51
shadow_console_enabled(void)52 __init int shadow_console_enabled(void)
53 {
54 return early_shadow_console.flags & CON_ENABLED;
55 }
56
mark_shadow_error(void)57 __init void mark_shadow_error(void)
58 {
59 int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
60 loc[0] = SHADOW_CONSOLE_MAGIC;
61 loc[1] = SHADOW_CONSOLE_START;
62 }
63
enable_shadow_console(void)64 __init void enable_shadow_console(void)
65 {
66 if (!shadow_console_enabled()) {
67 register_console(&early_shadow_console);
68 /* for now, assume things are going to fail */
69 mark_shadow_error();
70 }
71 }
72
disable_shadow_console(void)73 static __init int disable_shadow_console(void)
74 {
75 /*
76 * by the time pure_initcall runs, the standard console is enabled,
77 * and the early_console is off, so unset the magic numbers
78 * unregistering the console is taken care of in common code (See
79 * ./kernel/printk:disable_boot_consoles() )
80 */
81 int *loc = (int *)SHADOW_CONSOLE_MAGIC_LOC;
82
83 loc[0] = 0;
84
85 return 0;
86 }
87 pure_initcall(disable_shadow_console);
88
89 /*
90 * since we can't use printk, dump numbers (as hex), n = # bits
91 */
early_shadow_reg(unsigned long reg,unsigned int n)92 __init void early_shadow_reg(unsigned long reg, unsigned int n)
93 {
94 /*
95 * can't use any "normal" kernel features, since thay
96 * may not be relocated to their execute address yet
97 */
98 int i;
99 char ascii[11] = " 0x";
100
101 n = n / 4;
102 reg = reg << ((8 - n) * 4);
103 n += 3;
104
105 for (i = 3; i <= n ; i++) {
106 ascii[i] = hex_asc_lo(reg >> 28);
107 reg <<= 4;
108 }
109 early_shadow_write(NULL, ascii, n);
110
111 }
112