tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * COM1 NS16550 support
3 */
4
5#include <linux/config.h>
6#include <linux/types.h>
7#include <linux/serial.h>
8#include <linux/serial_reg.h>
9#include <asm/serial.h>
10
11#include "nonstdio.h"
12#include "serial.h"
13
14#define SERIAL_BAUD 9600
15
16extern unsigned long ISA_io;
17
18static struct serial_state rs_table[RS_TABLE_SIZE] = {
19 SERIAL_PORT_DFNS /* Defined in <asm/serial.h> */
20};
21
22static int shift;
23
24unsigned long serial_init(int chan, void *ignored)
25{
26 unsigned long com_port;
27 unsigned char lcr, dlm;
28
29 /* We need to find out which type io we're expecting. If it's
30 * 'SERIAL_IO_PORT', we get an offset from the isa_io_base.
31 * If it's 'SERIAL_IO_MEM', we can the exact location. -- Tom */
32 switch (rs_table[chan].io_type) {
33 case SERIAL_IO_PORT:
34 com_port = rs_table[chan].port;
35 break;
36 case SERIAL_IO_MEM:
37 com_port = (unsigned long)rs_table[chan].iomem_base;
38 break;
39 default:
40 /* We can't deal with it. */
41 return -1;
42 }
43
44 /* How far apart the registers are. */
45 shift = rs_table[chan].iomem_reg_shift;
46
47 /* save the LCR */
48 lcr = inb(com_port + (UART_LCR << shift));
49 /* Access baud rate */
50 outb(com_port + (UART_LCR << shift), 0x80);
51 dlm = inb(com_port + (UART_DLM << shift));
52 /*
53 * Test if serial port is unconfigured.
54 * We assume that no-one uses less than 110 baud or
55 * less than 7 bits per character these days.
56 * -- paulus.
57 */
58
59 if ((dlm <= 4) && (lcr & 2))
60 /* port is configured, put the old LCR back */
61 outb(com_port + (UART_LCR << shift), lcr);
62 else {
63 /* Input clock. */
64 outb(com_port + (UART_DLL << shift),
65 (BASE_BAUD / SERIAL_BAUD) & 0xFF);
66 outb(com_port + (UART_DLM << shift),
67 (BASE_BAUD / SERIAL_BAUD) >> 8);
68 /* 8 data, 1 stop, no parity */
69 outb(com_port + (UART_LCR << shift), 0x03);
70 /* RTS/DTR */
71 outb(com_port + (UART_MCR << shift), 0x03);
72 }
73 /* Clear & enable FIFOs */
74 outb(com_port + (UART_FCR << shift), 0x07);
75
76 return (com_port);
77}
78
79void
80serial_putc(unsigned long com_port, unsigned char c)
81{
82 while ((inb(com_port + (UART_LSR << shift)) & UART_LSR_THRE) == 0)
83 ;
84 outb(com_port, c);
85}
86
87unsigned char
88serial_getc(unsigned long com_port)
89{
90 while ((inb(com_port + (UART_LSR << shift)) & UART_LSR_DR) == 0)
91 ;
92 return inb(com_port);
93}
94
95int
96serial_tstc(unsigned long com_port)
97{
98 return ((inb(com_port + (UART_LSR << shift)) & UART_LSR_DR) != 0);
99}