Commit | Line | Data |
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89272a51 MS |
1 | /* |
2 | * Early printk support for Microblaze. | |
3 | * | |
4 | * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu> | |
5 | * Copyright (C) 2007-2009 PetaLogix | |
6 | * Copyright (C) 2003-2006 Yasushi SHOJI <yashi@atmark-techno.com> | |
7 | * | |
8 | * This file is subject to the terms and conditions of the GNU General Public | |
9 | * License. See the file "COPYING" in the main directory of this archive | |
10 | * for more details. | |
11 | */ | |
12 | ||
13 | #include <linux/console.h> | |
14 | #include <linux/kernel.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/string.h> | |
17 | #include <linux/tty.h> | |
18 | #include <linux/io.h> | |
19 | #include <asm/processor.h> | |
20 | #include <linux/fcntl.h> | |
21 | #include <asm/setup.h> | |
22 | #include <asm/prom.h> | |
23 | ||
24 | static u32 early_console_initialized; | |
25 | static u32 base_addr; | |
26 | ||
27 | static void early_printk_putc(char c) | |
28 | { | |
29 | /* | |
30 | * Limit how many times we'll spin waiting for TX FIFO status. | |
31 | * This will prevent lockups if the base address is incorrectly | |
32 | * set, or any other issue on the UARTLITE. | |
33 | * This limit is pretty arbitrary, unless we are at about 10 baud | |
34 | * we'll never timeout on a working UART. | |
35 | */ | |
36 | ||
37 | unsigned retries = 10000; | |
38 | /* read status bit - 0x8 offset */ | |
39 | while (retries-- && (in_be32(base_addr + 8) & (1 << 3))) | |
40 | ; | |
41 | ||
42 | /* Only attempt the iowrite if we didn't timeout */ | |
43 | /* write to TX_FIFO - 0x4 offset */ | |
44 | if (retries) | |
45 | out_be32(base_addr + 4, c & 0xff); | |
46 | } | |
47 | ||
48 | static void early_printk_write(struct console *unused, | |
49 | const char *s, unsigned n) | |
50 | { | |
51 | while (*s && n-- > 0) { | |
52 | early_printk_putc(*s); | |
53 | if (*s == '\n') | |
54 | early_printk_putc('\r'); | |
55 | s++; | |
56 | } | |
57 | } | |
58 | ||
59 | static struct console early_serial_console = { | |
60 | .name = "earlyser", | |
61 | .write = early_printk_write, | |
62 | .flags = CON_PRINTBUFFER, | |
63 | .index = -1, | |
64 | }; | |
65 | ||
66 | static struct console *early_console = &early_serial_console; | |
67 | ||
68 | void early_printk(const char *fmt, ...) | |
69 | { | |
70 | char buf[512]; | |
71 | int n; | |
72 | va_list ap; | |
73 | ||
74 | if (early_console_initialized) { | |
75 | va_start(ap, fmt); | |
76 | n = vscnprintf(buf, 512, fmt, ap); | |
77 | early_console->write(early_console, buf, n); | |
78 | va_end(ap); | |
79 | } | |
80 | } | |
81 | ||
82 | int __init setup_early_printk(char *opt) | |
83 | { | |
84 | if (early_console_initialized) | |
85 | return 1; | |
86 | ||
87 | base_addr = early_uartlite_console(); | |
88 | if (base_addr) { | |
89 | early_console_initialized = 1; | |
90 | early_printk("early_printk_console is enabled at 0x%08x\n", | |
91 | base_addr); | |
92 | ||
93 | /* register_console(early_console); */ | |
94 | ||
95 | return 0; | |
96 | } else | |
97 | return 1; | |
98 | } | |
99 | ||
100 | void __init disable_early_printk(void) | |
101 | { | |
102 | if (!early_console_initialized || !early_console) | |
103 | return; | |
104 | printk(KERN_WARNING "disabling early console\n"); | |
105 | unregister_console(early_console); | |
106 | early_console_initialized = 0; | |
107 | } |