2 * Copyright (c) 1998 Michael Smith (msmith@freebsd.org)
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * $FreeBSD: src/sys/boot/i386/libi386/comconsole.c,v 1.10 2003/09/16 11:24:23 bde Exp $
26 * $DragonFly: src/sys/boot/pc32/libi386/comconsole.c,v 1.9 2004/06/27 21:27:36 dillon Exp $
30 #include <bootstrap.h>
31 #include <machine/cpufunc.h>
32 #include <dev/serial/ic_layer/ns16550.h>
35 #define COMC_FMT 0x3 /* 8N1 */
36 #define COMC_TXWAIT 0x40000 /* transmit timeout */
37 #define COMC_BPS(x) (115200 / (x)) /* speed to DLAB divisor */
46 static void comc_probe(struct console *cp);
47 static int comc_init(int arg);
48 static void comc_putchar(int c);
49 static int comc_getchar(void);
50 static int comc_ischar(void);
52 static int comc_started;
54 struct console comconsole = {
66 * Probe for a comconsole. If the comport is not mapped at boot time (which
67 * is often true on laptops), don't try to access it. If we can't clear
68 * the input fifo, don't try to access it later.
70 * Normally the stage-2 bootloader will do this detection and hand us
71 * appropriate flags, but some bootloaders (pxe, cdboot) load the loader
72 * directly so we have to check again here.
75 comc_probe(struct console *cp)
79 if (inb(COMPORT + com_lsr) == 0xFF)
81 for (i = 255; i >= 0; --i) {
82 if (comc_ischar() == 0)
84 inb(COMPORT + com_data);
88 cp->c_flags |= (C_PRESENTIN | C_PRESENTOUT);
94 if (comc_started && arg == 0)
98 outb(COMPORT + com_cfcr, CFCR_DLAB | COMC_FMT);
99 outb(COMPORT + com_dlbl, COMC_BPS(COMSPEED) & 0xff);
100 outb(COMPORT + com_dlbh, COMC_BPS(COMSPEED) >> 8);
101 outb(COMPORT + com_cfcr, COMC_FMT);
102 outb(COMPORT + com_mcr, MCR_RTS | MCR_DTR);
106 * Enable the FIFO so the serial port output in dual console mode doesn't
107 * interfere so much with the disk twiddle.
109 * DISABLED - apparently many new laptops implement only the base 8250,
110 * writing to this port can crash them.
112 outb(COMPORT + com_fifo, FIFO_ENABLE);
116 * Give the serial port a little time to settle after asserting RTS and
117 * DTR, then drain any pending garbage.
120 while (comc_ischar())
121 inb(COMPORT + com_data);
131 for (wait = COMC_TXWAIT; wait > 0; wait--) {
132 if (inb(COMPORT + com_lsr) & LSR_TXRDY) {
133 outb(COMPORT + com_data, (u_char)c);
142 return(comc_ischar() ? inb(COMPORT + com_data) : -1);
148 return(inb(COMPORT + com_lsr) & LSR_RXRDY);