1 /* $NetBSD: comio_direct.c,v 1.12 2022/09/05 14:14:42 tsutsui Exp $ */
2
3 /*-
4 * Copyright (c) 1993, 1994, 1995, 1996, 1997
5 * Charles M. Hannum. All rights reserved.
6 *
7 * Taken from sys/dev/isa/com.c and integrated into standalone boot
8 * programs by Martin Husemann.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by Charles M. Hannum.
21 * 4. The name of the author may not be used to endorse or promote products
22 * derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 /*
37 * Copyright (c) 1991 The Regents of the University of California.
38 * All rights reserved.
39 *
40 * Redistribution and use in source and binary forms, with or without
41 * modification, are permitted provided that the following conditions
42 * are met:
43 * 1. Redistributions of source code must retain the above copyright
44 * notice, this list of conditions and the following disclaimer.
45 * 2. Redistributions in binary form must reproduce the above copyright
46 * notice, this list of conditions and the following disclaimer in the
47 * documentation and/or other materials provided with the distribution.
48 * 3. Neither the name of the University nor the names of its contributors
49 * may be used to endorse or promote products derived from this software
50 * without specific prior written permission.
51 *
52 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
53 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
56 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62 * SUCH DAMAGE.
63 *
64 * @(#)com.c 7.5 (Berkeley) 5/16/91
65 */
66
67 #include <sys/types.h>
68 #include <lib/libsa/stand.h>
69 #include <machine/pio.h>
70 #include <dev/ic/comreg.h>
71 #include "comio_direct.h"
72 #include "libi386.h"
73
74 /* preread buffer for xon/xoff handling */
75 #define XON 0x11
76 #define XOFF 0x13
77 #define SERBUFSIZE 16
78 static u_char serbuf[SERBUFSIZE];
79 static int serbuf_read = 0;
80 static int serbuf_write = 0;
81 static int stopped = 0;
82
83 #define divrnd(n, q) (((n)*2/(q)+1)/2) /* divide and round off */
84 #define RATE_9600 divrnd((COM_FREQ / 16), 9600)
85
86 /*
87 * calculate divisor for a given speed
88 */
89 static int
comspeed(long speed)90 comspeed(long speed)
91 {
92 int x, err;
93
94 if (speed <= 0)
95 speed = 9600;
96 x = divrnd((COM_FREQ / 16), speed);
97 if (x <= 0)
98 return RATE_9600;
99 err = divrnd((COM_FREQ / 16) * 1000, speed * x) - 1000;
100 if (err < 0)
101 err = -err;
102 if (err > COM_TOLERANCE)
103 return RATE_9600;
104 return x;
105 }
106
107 /*
108 * get a character
109 */
110 int
comgetc_d(int combase)111 comgetc_d(int combase)
112 {
113 u_char stat, c;
114
115 if (serbuf_read != serbuf_write) {
116 c = serbuf[serbuf_read++];
117 if (serbuf_read >= SERBUFSIZE)
118 serbuf_read = 0;
119 return c;
120 }
121
122 for (;;) {
123 while (!ISSET(stat = inb(combase + com_lsr), LSR_RXRDY))
124 continue;
125 c = inb(combase + com_data);
126 inb(combase + com_iir);
127 if (c != XOFF) {
128 stopped = 0;
129 break; /* got a real char, deliver it... */
130 }
131 stopped = 1;
132 }
133 return c;
134 }
135
136 /*
137 * output a character, return nonzero on success
138 */
139 int
computc_d(int c,int combase)140 computc_d(int c, int combase)
141 {
142 u_char stat;
143 int timo;
144
145 /* check for old XOFF */
146 while (stopped)
147 comgetc_d(combase); /* wait for XON */
148
149 /* check for new XOFF */
150 if (comstatus_d(combase)) {
151 int x = comgetc_d(combase); /* XOFF handled in comgetc_d */
152 /* stuff char into preread buffer */
153 serbuf[serbuf_write++] = x;
154 if (serbuf_write >= SERBUFSIZE)
155 serbuf_write = 0;
156 }
157
158 /* wait for any pending transmission to finish */
159 timo = 50000;
160 while (!ISSET(stat = inb(combase + com_lsr), LSR_TXRDY)
161 && --timo)
162 continue;
163 if (timo == 0) return 0;
164 outb(combase + com_data, c);
165 /* wait for this transmission to complete */
166 timo = 1500000;
167 while (!ISSET(stat = inb(combase + com_lsr), LSR_TXRDY)
168 && --timo)
169 continue;
170 if (timo == 0) return 0;
171 /* clear any interrupts generated by this transmission */
172 inb(combase + com_iir);
173
174 return 1;
175 }
176
177 /*
178 * Initialize UART to known state.
179 */
180 int
cominit_d(int combase,int speed)181 cominit_d(int combase, int speed)
182 {
183 int rate, err;
184
185 serbuf_read = 0;
186 serbuf_write = 0;
187
188 outb(combase + com_cfcr, LCR_DLAB);
189 if (speed == 0) {
190 /* Try to determine the current baud rate */
191 rate = inb(combase + com_dlbl) | inb(combase + com_dlbh) << 8;
192 if (rate == 0)
193 rate = RATE_9600;
194 speed = divrnd((COM_FREQ / 16), rate);
195 err = speed - (speed + 150)/300 * 300;
196 speed -= err;
197 if (err < 0)
198 err = -err;
199 if (err > 50)
200 speed = 9600;
201 }
202 rate = comspeed(speed);
203 outb(combase + com_dlbl, rate);
204 outb(combase + com_dlbh, rate >> 8);
205 outb(combase + com_cfcr, LCR_8BITS);
206 outb(combase + com_mcr, MCR_DTR | MCR_RTS);
207 outb(combase + com_fifo,
208 FIFO_ENABLE | FIFO_RCV_RST | FIFO_XMT_RST | FIFO_TRIGGER_1);
209 outb(combase + com_ier, 0);
210
211 return speed;
212 }
213
214 /*
215 * return nonzero if input char available, do XON/XOFF handling
216 */
217 int
comstatus_d(int combase)218 comstatus_d(int combase)
219 {
220 /* check if any preread input is already there */
221 if (serbuf_read != serbuf_write) return 1;
222
223 /* check for new stuff on the port */
224 if (ISSET(inb(combase + com_lsr), LSR_RXRDY)) {
225 /* this could be XOFF, which we would swallow, so we can't
226 claim there is input available... */
227 int c = inb(combase + com_data);
228 inb(combase + com_iir);
229 if (c == XOFF) {
230 stopped = 1;
231 } else {
232 /* stuff char into preread buffer */
233 serbuf[serbuf_write++] = c;
234 if (serbuf_write >= SERBUFSIZE)
235 serbuf_write = 0;
236 return 1;
237 }
238 }
239
240 return 0; /* nothing out there... */
241 }
242