- 根目录:
- arch
- x86
- boot
- early_serial_console.c
#include "boot.h"
#define DEFAULT_SERIAL_PORT 0x3f8
#define XMTRDY 0x20
#define DLAB 0x80
#define TXR 0
#define RXR 0
#define IER 1
#define IIR 2
#define FCR 2
#define LCR 3
#define MCR 4
#define LSR 5
#define MSR 6
#define DLL 0
#define DLH 1
#define DEFAULT_BAUD 9600
static void early_serial_init(int port, int baud)
{
unsigned char c;
unsigned divisor;
outb(0x3, port + LCR);
outb(0, port + IER);
outb(0, port + FCR);
outb(0x3, port + MCR);
divisor = 115200 / baud;
c = inb(port + LCR);
outb(c | DLAB, port + LCR);
outb(divisor & 0xff, port + DLL);
outb((divisor >> 8) & 0xff, port + DLH);
outb(c & ~DLAB, port + LCR);
early_serial_base = port;
}
static void parse_earlyprintk(void)
{
int baud = DEFAULT_BAUD;
char arg[32];
int pos = 0;
int port = 0;
if (cmdline_find_option("earlyprintk", arg, sizeof arg) > 0) {
char *e;
if (!strncmp(arg, "serial", 6)) {
port = DEFAULT_SERIAL_PORT;
pos += 6;
}
if (arg[pos] == ',')
pos++;
if (pos == 7 && !strncmp(arg + pos, "0x", 2)) {
port = simple_strtoull(arg + pos, &e, 16);
if (port == 0 || arg + pos == e)
port = DEFAULT_SERIAL_PORT;
else
pos = e - arg;
} else if (!strncmp(arg + pos, "ttyS", 4)) {
static const int bases[] = { 0x3f8, 0x2f8 };
int idx = 0;
if (!strncmp(arg + pos, "ttyS", 4))
pos += 4;
if (arg[pos++] == '1')
idx = 1;
port = bases[idx];
}
if (arg[pos] == ',')
pos++;
baud = simple_strtoull(arg + pos, &e, 0);
if (baud == 0 || arg + pos == e)
baud = DEFAULT_BAUD;
}
if (port)
early_serial_init(port, baud);
}
#define BASE_BAUD (1843200/16)
static unsigned int probe_baud(int port)
{
unsigned char lcr, dll, dlh;
unsigned int quot;
lcr = inb(port + LCR);
outb(lcr | DLAB, port + LCR);
dll = inb(port + DLL);
dlh = inb(port + DLH);
outb(lcr, port + LCR);
quot = (dlh << 8) | dll;
return BASE_BAUD / quot;
}
static void parse_console_uart8250(void)
{
char optstr[64], *options;
int baud = DEFAULT_BAUD;
int port = 0;
if (cmdline_find_option("console", optstr, sizeof optstr) <= 0)
return;
options = optstr;
if (!strncmp(options, "uart8250,io,", 12))
port = simple_strtoull(options + 12, &options, 0);
else if (!strncmp(options, "uart,io,", 8))
port = simple_strtoull(options + 8, &options, 0);
else
return;
if (options && (options[0] == ','))
baud = simple_strtoull(options + 1, &options, 0);
else
baud = probe_baud(port);
if (port)
early_serial_init(port, baud);
}
void console_init(void)
{
parse_earlyprintk();
if (!early_serial_base)
parse_console_uart8250();
}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- 89
- 90
- 91
- 92
- 93
- 94
- 95
- 96
- 97
- 98
- 99
- 100
- 101
- 102
- 103
- 104
- 105
- 106
- 107
- 108
- 109
- 110
- 111
- 112
- 113
- 114
- 115
- 116
- 117
- 118
- 119
- 120
- 121
- 122
- 123
- 124
- 125
- 126
- 127
- 128
- 129
- 130
- 131
- 132
- 133
- 134
- 135
- 136
- 137
- 138
- 139
- 140
- 141
- 142
- 143
- 144
- 145
- 146
- 147
- 148
- 149
- 150
- 151