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
|
#include <part/fallback_boot.h>
/* Base Address */
#ifndef TTYS0_BASE
#define TTYS0_BASE 0x3f8
#endif
#ifndef TTYS0_BAUD
#define TTYS0_BAUD 115200
#endif
#if ((115200%TTYS0_BAUD) != 0)
#error Bad ttys0 baud rate
#endif
#define TTYS0_DIV (115200/TTYS0_BAUD)
/* Line Control Settings */
#ifndef TTYS0_LCS
/* Set 8bit, 1 stop bit, no parity */
#define TTYS0_LCS 0x3
#endif
#define UART_LCS TTYS0_LCS
/* Data */
#define UART_RBR 0x00
#define UART_TBR 0x00
/* Control */
#define UART_IER 0x01
#define UART_IIR 0x02
#define UART_FCR 0x02
#define UART_LCR 0x03
#define UART_MCR 0x04
#define UART_DLL 0x00
#define UART_DLM 0x01
/* Status */
#define UART_LSR 0x05
#define UART_MSR 0x06
#define UART_SCR 0x07
static int uart_can_tx_byte(void)
{
return inb(TTYS0_BASE + UART_LSR) & 0x20;
}
static void uart_wait_to_tx_byte(void)
{
while(!uart_can_tx_byte())
;
}
static void uart_wait_until_sent(void)
{
while(!(inb(TTYS0_BASE + UART_LSR) & 0x40))
;
}
static void uart_tx_byte(unsigned char data)
{
uart_wait_to_tx_byte();
outb(data, TTYS0_BASE + UART_TBR);
/* Make certain the data clears the fifos */
uart_wait_until_sent();
}
static void uart_init(void)
{
/* disable interrupts */
outb(0x0, TTYS0_BASE + UART_IER);
/* enable fifo's */
outb(0x01, TTYS0_BASE + UART_FCR);
/* Set Baud Rate Divisor to 12 ==> 115200 Baud */
outb(0x80 | UART_LCS, TTYS0_BASE + UART_LCR);
#if USE_OPTION_TABLE == 1
static const unsigned char divisor[] = { 1,2,3,6,12,24,48,96 };
unsigned ttys0_div, ttys0_index;
outb(RTC_BOOT_BYTE + 1, 0x70);
ttys0_index = inb(0x71);
ttys0_index &= 7;
ttys0_div = divisor[ttys0_index];
outb(ttys0_div & 0xff, TTYS0_BASE + UART_DLL);
outb(0, TTYS0_BASE + UART_DLM);
#else
outb(TTYS0_DIV & 0xFF, TTYS0_BASE + UART_DLL);
outb((TTYS0_DIV >> 8) & 0xFF, TTYS0_BASE + UART_DLM);
#endif
outb(UART_LCS, TTYS0_BASE + UART_LCR);
}
|
