tty.c (70b0d22d581a5deef7b2876b0c3774635b8d846c) tty.c (f4ed2877b16e8146427306aea8819adac5c88374)
1/* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright 2007 rPath, Inc. - All Rights Reserved
5 * Copyright 2009 Intel Corporation; author H. Peter Anvin
6 *
7 * This file is part of the Linux kernel, and is made available under
8 * the terms of the GNU General Public License version 2.
9 *
10 * ----------------------------------------------------------------------- */
11
12/*
13 * Very simple screen and serial I/O
14 */
15
16#include "boot.h"
17
1/* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright 2007 rPath, Inc. - All Rights Reserved
5 * Copyright 2009 Intel Corporation; author H. Peter Anvin
6 *
7 * This file is part of the Linux kernel, and is made available under
8 * the terms of the GNU General Public License version 2.
9 *
10 * ----------------------------------------------------------------------- */
11
12/*
13 * Very simple screen and serial I/O
14 */
15
16#include "boot.h"
17
18#define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */
18int early_serial_base;
19
19
20static int early_serial_base;
21
22#define XMTRDY 0x20
23
20#define XMTRDY 0x20
21
24#define DLAB 0x80
25
26#define TXR 0 /* Transmit register (WRITE) */
22#define TXR 0 /* Transmit register (WRITE) */
27#define RXR 0 /* Receive register (READ) */
28#define IER 1 /* Interrupt Enable */
29#define IIR 2 /* Interrupt ID */
30#define FCR 2 /* FIFO control */
31#define LCR 3 /* Line control */
32#define MCR 4 /* Modem control */
33#define LSR 5 /* Line Status */
23#define LSR 5 /* Line Status */
34#define MSR 6 /* Modem Status */
35#define DLL 0 /* Divisor Latch Low */
36#define DLH 1 /* Divisor latch High */
37
24
38#define DEFAULT_BAUD 9600
39
40/*
41 * These functions are in .inittext so they can be used to signal
42 * error during initialization.
43 */
44
45static void __attribute__((section(".inittext"))) serial_putchar(int ch)
46{
47 unsigned timeout = 0xffff;

--- 99 unchanged lines hidden (view full) ---

147 cnt--;
148 t0 = t1;
149 }
150 }
151
152 return 0; /* Timeout! */
153}
154
25/*
26 * These functions are in .inittext so they can be used to signal
27 * error during initialization.
28 */
29
30static void __attribute__((section(".inittext"))) serial_putchar(int ch)
31{
32 unsigned timeout = 0xffff;

--- 99 unchanged lines hidden (view full) ---

132 cnt--;
133 t0 = t1;
134 }
135 }
136
137 return 0; /* Timeout! */
138}
139
155static void early_serial_init(int port, int baud)
156{
157 unsigned char c;
158 unsigned divisor;
159
160 outb(0x3, port + LCR); /* 8n1 */
161 outb(0, port + IER); /* no interrupt */
162 outb(0, port + FCR); /* no fifo */
163 outb(0x3, port + MCR); /* DTR + RTS */
164
165 divisor = 115200 / baud;
166 c = inb(port + LCR);
167 outb(c | DLAB, port + LCR);
168 outb(divisor & 0xff, port + DLL);
169 outb((divisor >> 8) & 0xff, port + DLH);
170 outb(c & ~DLAB, port + LCR);
171
172 early_serial_base = port;
173
174 printf("Early serial console at I/O port 0x%x baud: %d\n", port, baud);
175}
176
177static void parse_earlyprintk(void)
178{
179 int baud = DEFAULT_BAUD;
180 char arg[32];
181 int pos = 0;
182 int port = 0;
183
184 if (cmdline_find_option("earlyprintk", arg, sizeof arg) > 0) {
185 char *e;
186
187 if (!strncmp(arg, "serial", 6)) {
188 port = DEFAULT_SERIAL_PORT;
189 pos += 6;
190 }
191
192 if (arg[pos] == ',')
193 pos++;
194
195 if (!strncmp(arg, "ttyS", 4)) {
196 static const int bases[] = { 0x3f8, 0x2f8 };
197 int idx = 0;
198
199 if (!strncmp(arg + pos, "ttyS", 4))
200 pos += 4;
201
202 if (arg[pos++] == '1')
203 idx = 1;
204
205 port = bases[idx];
206 }
207
208 if (arg[pos] == ',')
209 pos++;
210
211 baud = simple_strtoull(arg + pos, &e, 0);
212 if (baud == 0 || arg + pos == e)
213 baud = DEFAULT_BAUD;
214 }
215
216 if (port)
217 early_serial_init(port, baud);
218}
219
220#define BASE_BAUD (1843200/16)
221static unsigned int probe_baud(int port)
222{
223 unsigned char lcr, dll, dlh;
224 unsigned int quot;
225
226 lcr = inb(port + LCR);
227 outb(lcr | DLAB, port + LCR);
228 dll = inb(port + DLL);
229 dlh = inb(port + DLH);
230 outb(lcr, port + LCR);
231 quot = (dlh << 8) | dll;
232
233 return BASE_BAUD / quot;
234}
235
236static void parse_console_uart8250(void)
237{
238 char optstr[64], *options;
239 int baud = DEFAULT_BAUD;
240 int port = 0;
241
242 /*
243 * console=uart8250,io,0x3f8,115200n8
244 * need to make sure it is last one console !
245 */
246 if (cmdline_find_option("console", optstr, sizeof optstr) <= 0)
247 return;
248
249 options = optstr;
250
251 if (!strncmp(options, "uart8250,io,", 12))
252 port = simple_strtoull(options + 12, &options, 0);
253 else if (!strncmp(options, "uart,io,", 8))
254 port = simple_strtoull(options + 8, &options, 0);
255 else
256 return;
257
258 if (options && (options[0] == ','))
259 baud = simple_strtoull(options + 1, &options, 0);
260 else
261 baud = probe_baud(port);
262
263 if (port)
264 early_serial_init(port, baud);
265}
266
267void console_init(void)
268{
269 parse_earlyprintk();
270
271 if (!early_serial_base)
272 parse_console_uart8250();
273}