Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx
[linux-2.6.git] / arch / microblaze / kernel / early_printk.c
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 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
28 static void early_printk_uartlite_putc(char c)
29 {
30         /*
31          * Limit how many times we'll spin waiting for TX FIFO status.
32          * This will prevent lockups if the base address is incorrectly
33          * set, or any other issue on the UARTLITE.
34          * This limit is pretty arbitrary, unless we are at about 10 baud
35          * we'll never timeout on a working UART.
36          */
37
38         unsigned retries = 10000;
39         /* read status bit - 0x8 offset */
40         while (--retries && (in_be32(base_addr + 8) & (1 << 3)))
41                 ;
42
43         /* Only attempt the iowrite if we didn't timeout */
44         /* write to TX_FIFO - 0x4 offset */
45         if (retries)
46                 out_be32(base_addr + 4, c & 0xff);
47 }
48
49 static void early_printk_uartlite_write(struct console *unused,
50                                         const char *s, unsigned n)
51 {
52         while (*s && n-- > 0) {
53                 early_printk_uartlite_putc(*s);
54                 if (*s == '\n')
55                         early_printk_uartlite_putc('\r');
56                 s++;
57         }
58 }
59
60 static struct console early_serial_uartlite_console = {
61         .name = "earlyser",
62         .write = early_printk_uartlite_write,
63         .flags = CON_PRINTBUFFER,
64         .index = -1,
65 };
66 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
67
68 #ifdef CONFIG_SERIAL_8250_CONSOLE
69 static void early_printk_uart16550_putc(char c)
70 {
71         /*
72          * Limit how many times we'll spin waiting for TX FIFO status.
73          * This will prevent lockups if the base address is incorrectly
74          * set, or any other issue on the UARTLITE.
75          * This limit is pretty arbitrary, unless we are at about 10 baud
76          * we'll never timeout on a working UART.
77          */
78
79         #define UART_LSR_TEMT   0x40 /* Transmitter empty */
80         #define UART_LSR_THRE   0x20 /* Transmit-hold-register empty */
81         #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
82
83         unsigned retries = 10000;
84
85         while (--retries &&
86                 !((in_be32(base_addr + 0x14) & BOTH_EMPTY) == BOTH_EMPTY))
87                 ;
88
89         if (retries)
90                 out_be32(base_addr, c & 0xff);
91 }
92
93 static void early_printk_uart16550_write(struct console *unused,
94                                         const char *s, unsigned n)
95 {
96         while (*s && n-- > 0) {
97                 early_printk_uart16550_putc(*s);
98                 if (*s == '\n')
99                         early_printk_uart16550_putc('\r');
100                 s++;
101         }
102 }
103
104 static struct console early_serial_uart16550_console = {
105         .name = "earlyser",
106         .write = early_printk_uart16550_write,
107         .flags = CON_PRINTBUFFER,
108         .index = -1,
109 };
110 #endif /* CONFIG_SERIAL_8250_CONSOLE */
111
112 static struct console *early_console;
113
114 void early_printk(const char *fmt, ...)
115 {
116         char buf[512];
117         int n;
118         va_list ap;
119
120         if (early_console_initialized) {
121                 va_start(ap, fmt);
122                 n = vscnprintf(buf, 512, fmt, ap);
123                 early_console->write(early_console, buf, n);
124                 va_end(ap);
125         }
126 }
127
128 int __init setup_early_printk(char *opt)
129 {
130         if (early_console_initialized)
131                 return 1;
132
133 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
134         base_addr = early_uartlite_console();
135         if (base_addr) {
136                 early_console_initialized = 1;
137 #ifdef CONFIG_MMU
138                 early_console_reg_tlb_alloc(base_addr);
139 #endif
140                 early_console = &early_serial_uartlite_console;
141                 early_printk("early_printk_console is enabled at 0x%08x\n",
142                                                         base_addr);
143
144                 /* register_console(early_console); */
145
146                 return 0;
147         }
148 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
149
150 #ifdef CONFIG_SERIAL_8250_CONSOLE
151         base_addr = early_uart16550_console();
152         base_addr &= ~3; /* clear register offset */
153         if (base_addr) {
154                 early_console_initialized = 1;
155 #ifdef CONFIG_MMU
156                 early_console_reg_tlb_alloc(base_addr);
157 #endif
158                 early_console = &early_serial_uart16550_console;
159
160                 early_printk("early_printk_console is enabled at 0x%08x\n",
161                                                         base_addr);
162
163                 /* register_console(early_console); */
164
165                 return 0;
166         }
167 #endif /* CONFIG_SERIAL_8250_CONSOLE */
168
169         return 1;
170 }
171
172 void __init disable_early_printk(void)
173 {
174         if (!early_console_initialized || !early_console)
175                 return;
176         printk(KERN_WARNING "disabling early console\n");
177         unregister_console(early_console);
178         early_console_initialized = 0;
179 }