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
|
#include "boot.h"
#define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */
#define DLAB 0x80
#define TXR 0 /* Transmit register (WRITE) */
#define RXR 0 /* Receive register (READ) */
#define IER 1 /* Interrupt Enable */
#define IIR 2 /* Interrupt ID */
#define FCR 2 /* FIFO control */
#define LCR 3 /* Line control */
#define MCR 4 /* Modem control */
#define LSR 5 /* Line Status */
#define MSR 6 /* Modem Status */
#define DLL 0 /* Divisor Latch Low */
#define DLH 1 /* Divisor latch High */
#define DEFAULT_BAUD 9600
static void early_serial_init(int port, int baud)
{
unsigned char c;
unsigned divisor;
outb(0x3, port + LCR); /* 8n1 */
outb(0, port + IER); /* no interrupt */
outb(0, port + FCR); /* no fifo */
outb(0x3, port + MCR); /* DTR + RTS */
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++;
/*
* make sure we have
* "serial,0x3f8,115200"
* "serial,ttyS0,115200"
* "ttyS0,115200"
*/
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;
/*
* console=uart8250,io,0x3f8,115200n8
* need to make sure it is last one console !
*/
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();
}
|
