aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86_64/kernel/early_printk.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/x86_64/kernel/early_printk.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/x86_64/kernel/early_printk.c')
-rw-r--r--arch/x86_64/kernel/early_printk.c220
1 files changed, 220 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/early_printk.c b/arch/x86_64/kernel/early_printk.c
new file mode 100644
index 000000000000..750bcd0655dc
--- /dev/null
+++ b/arch/x86_64/kernel/early_printk.c
@@ -0,0 +1,220 @@
1#include <linux/console.h>
2#include <linux/kernel.h>
3#include <linux/init.h>
4#include <linux/string.h>
5#include <asm/io.h>
6#include <asm/processor.h>
7
8/* Simple VGA output */
9
10#ifdef __i386__
11#define VGABASE (__ISA_IO_base + 0xb8000)
12#else
13#define VGABASE ((void __iomem *)0xffffffff800b8000UL)
14#endif
15
16#define MAX_YPOS 25
17#define MAX_XPOS 80
18
19static int current_ypos = 1, current_xpos = 0;
20
21static void early_vga_write(struct console *con, const char *str, unsigned n)
22{
23 char c;
24 int i, k, j;
25
26 while ((c = *str++) != '\0' && n-- > 0) {
27 if (current_ypos >= MAX_YPOS) {
28 /* scroll 1 line up */
29 for (k = 1, j = 0; k < MAX_YPOS; k++, j++) {
30 for (i = 0; i < MAX_XPOS; i++) {
31 writew(readw(VGABASE + 2*(MAX_XPOS*k + i)),
32 VGABASE + 2*(MAX_XPOS*j + i));
33 }
34 }
35 for (i = 0; i < MAX_XPOS; i++)
36 writew(0x720, VGABASE + 2*(MAX_XPOS*j + i));
37 current_ypos = MAX_YPOS-1;
38 }
39 if (c == '\n') {
40 current_xpos = 0;
41 current_ypos++;
42 } else if (c != '\r') {
43 writew(((0x7 << 8) | (unsigned short) c),
44 VGABASE + 2*(MAX_XPOS*current_ypos +
45 current_xpos++));
46 if (current_xpos >= MAX_XPOS) {
47 current_xpos = 0;
48 current_ypos++;
49 }
50 }
51 }
52}
53
54static struct console early_vga_console = {
55 .name = "earlyvga",
56 .write = early_vga_write,
57 .flags = CON_PRINTBUFFER,
58 .index = -1,
59};
60
61/* Serial functions loosely based on a similar package from Klaus P. Gerlicher */
62
63int early_serial_base = 0x3f8; /* ttyS0 */
64
65#define XMTRDY 0x20
66
67#define DLAB 0x80
68
69#define TXR 0 /* Transmit register (WRITE) */
70#define RXR 0 /* Receive register (READ) */
71#define IER 1 /* Interrupt Enable */
72#define IIR 2 /* Interrupt ID */
73#define FCR 2 /* FIFO control */
74#define LCR 3 /* Line control */
75#define MCR 4 /* Modem control */
76#define LSR 5 /* Line Status */
77#define MSR 6 /* Modem Status */
78#define DLL 0 /* Divisor Latch Low */
79#define DLH 1 /* Divisor latch High */
80
81static int early_serial_putc(unsigned char ch)
82{
83 unsigned timeout = 0xffff;
84 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
85 cpu_relax();
86 outb(ch, early_serial_base + TXR);
87 return timeout ? 0 : -1;
88}
89
90static void early_serial_write(struct console *con, const char *s, unsigned n)
91{
92 while (*s && n-- > 0) {
93 early_serial_putc(*s);
94 if (*s == '\n')
95 early_serial_putc('\r');
96 s++;
97 }
98}
99
100#define DEFAULT_BAUD 9600
101
102static __init void early_serial_init(char *s)
103{
104 unsigned char c;
105 unsigned divisor;
106 unsigned baud = DEFAULT_BAUD;
107 char *e;
108
109 if (*s == ',')
110 ++s;
111
112 if (*s) {
113 unsigned port;
114 if (!strncmp(s,"0x",2)) {
115 early_serial_base = simple_strtoul(s, &e, 16);
116 } else {
117 static int bases[] = { 0x3f8, 0x2f8 };
118
119 if (!strncmp(s,"ttyS",4))
120 s += 4;
121 port = simple_strtoul(s, &e, 10);
122 if (port > 1 || s == e)
123 port = 0;
124 early_serial_base = bases[port];
125 }
126 s += strcspn(s, ",");
127 if (*s == ',')
128 s++;
129 }
130
131 outb(0x3, early_serial_base + LCR); /* 8n1 */
132 outb(0, early_serial_base + IER); /* no interrupt */
133 outb(0, early_serial_base + FCR); /* no fifo */
134 outb(0x3, early_serial_base + MCR); /* DTR + RTS */
135
136 if (*s) {
137 baud = simple_strtoul(s, &e, 0);
138 if (baud == 0 || s == e)
139 baud = DEFAULT_BAUD;
140 }
141
142 divisor = 115200 / baud;
143 c = inb(early_serial_base + LCR);
144 outb(c | DLAB, early_serial_base + LCR);
145 outb(divisor & 0xff, early_serial_base + DLL);
146 outb((divisor >> 8) & 0xff, early_serial_base + DLH);
147 outb(c & ~DLAB, early_serial_base + LCR);
148}
149
150static struct console early_serial_console = {
151 .name = "earlyser",
152 .write = early_serial_write,
153 .flags = CON_PRINTBUFFER,
154 .index = -1,
155};
156
157/* Direct interface for emergencies */
158struct console *early_console = &early_vga_console;
159static int early_console_initialized = 0;
160
161void early_printk(const char *fmt, ...)
162{
163 char buf[512];
164 int n;
165 va_list ap;
166
167 va_start(ap,fmt);
168 n = vscnprintf(buf,512,fmt,ap);
169 early_console->write(early_console,buf,n);
170 va_end(ap);
171}
172
173static int keep_early;
174
175int __init setup_early_printk(char *opt)
176{
177 char *space;
178 char buf[256];
179
180 if (early_console_initialized)
181 return -1;
182
183 opt = strchr(opt, '=') + 1;
184
185 strlcpy(buf,opt,sizeof(buf));
186 space = strchr(buf, ' ');
187 if (space)
188 *space = 0;
189
190 if (strstr(buf,"keep"))
191 keep_early = 1;
192
193 if (!strncmp(buf, "serial", 6)) {
194 early_serial_init(buf + 6);
195 early_console = &early_serial_console;
196 } else if (!strncmp(buf, "ttyS", 4)) {
197 early_serial_init(buf);
198 early_console = &early_serial_console;
199 } else if (!strncmp(buf, "vga", 3)) {
200 early_console = &early_vga_console;
201 }
202 early_console_initialized = 1;
203 register_console(early_console);
204 return 0;
205}
206
207void __init disable_early_printk(void)
208{
209 if (!early_console_initialized || !early_console)
210 return;
211 if (!keep_early) {
212 printk("disabling early console\n");
213 unregister_console(early_console);
214 early_console_initialized = 0;
215 } else {
216 printk("keeping early console\n");
217 }
218}
219
220__setup("earlyprintk=", setup_early_printk);