source: SVN/rincon/u-boot/cpu/i386/timer.c @ 55

Last change on this file since 55 was 55, checked in by Tim Harvey, 22 months ago

rincon: added latest u-boot source

restored form server backup

Signed-off-by: Tim Harvey <tharvey@…>

File size: 4.1 KB
Line 
1/*
2 * (C) Copyright 2002
3 * Daniel Engström, Omicron Ceti AB, daniel@omicron.se.
4 *
5 * See file CREDITS for list of people who contributed to this
6 * project.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21 * MA 02111-1307 USA
22 */
23
24#include <common.h>
25#include <asm/io.h>
26#include <asm/i8254.h>
27#include <asm/ibmpc.h>
28
29
30static volatile unsigned long system_ticks;
31static int timer_init_done =0;
32
33static void timer_isr(void *unused)
34{
35        system_ticks++;
36}
37
38unsigned long get_system_ticks(void)
39{
40        return system_ticks;
41}
42
43#define TIMER0_VALUE 0x04aa /* 1kHz 1.9318MHz / 1000 */
44#define TIMER2_VALUE 0x0a8e /* 440Hz */
45
46int timer_init(void)
47{
48        system_ticks = 0;
49
50        irq_install_handler(0, timer_isr, NULL);
51
52        /* initialize timer 0 and 2
53         *
54         * Timer 0 is used to increment system_tick 1000 times/sec
55         * Timer 1 was used for DRAM refresh in early PC's
56         * Timer 2 is used to drive the speaker
57         * (to stasrt a beep: write 3 to port 0x61,
58         * to stop it again: write 0)
59         */
60
61        outb(PIT_CMD_CTR0|PIT_CMD_BOTH|PIT_CMD_MODE2, PIT_BASE + PIT_COMMAND);
62        outb(TIMER0_VALUE&0xff, PIT_BASE + PIT_T0);
63        outb(TIMER0_VALUE>>8, PIT_BASE + PIT_T0);
64
65        outb(PIT_CMD_CTR2|PIT_CMD_BOTH|PIT_CMD_MODE3, PIT_BASE + PIT_COMMAND);
66        outb(TIMER2_VALUE&0xff, PIT_BASE + PIT_T2);
67        outb(TIMER2_VALUE>>8, PIT_BASE + PIT_T2);
68
69        timer_init_done = 1;
70
71        return 0;
72}
73
74
75#ifdef CFG_TIMER_GENERIC
76
77/* the unit for these is CFG_HZ */
78
79/* FixMe: implement these */
80void reset_timer (void)
81{
82        system_ticks = 0;
83}
84
85ulong get_timer (ulong base)
86{
87        return (system_ticks - base);
88}
89
90void set_timer (ulong t)
91{
92        system_ticks = t;
93}
94
95static u16 read_pit(void)
96{
97        u8 low;
98        outb(PIT_CMD_LATCH, PIT_BASE + PIT_COMMAND);
99        low = inb(PIT_BASE + PIT_T0);
100        return ((inb(PIT_BASE + PIT_T0) << 8) | low);
101}
102
103/* this is not very exact */
104void udelay (unsigned long usec)
105{
106        int counter;
107        int wraps;
108
109        if (!timer_init_done) {
110                return;
111        }
112        counter = read_pit();
113        wraps = usec/1000;
114        usec = usec%1000;
115
116        usec*=1194;
117        usec/=1000;
118        usec+=counter;
119        if (usec > 1194) {
120                usec-=1194;
121                wraps++;
122        }
123
124        while (1) {
125                int new_count = read_pit();
126
127                if (((new_count < usec) && !wraps) || wraps < 0) {
128                        break;
129                }
130
131                if (new_count > counter) {
132                        wraps--;
133                }
134                counter = new_count;
135        }
136
137}
138
139#if 0
140/* this is a version with debug output */
141void _udelay (unsigned long usec)
142{
143        int counter;
144        int wraps;
145
146        int usec1, usec2, usec3;
147        int wraps1, wraps2, wraps3, wraps4;
148        int ctr1, ctr2, ctr3, nct1, nct2;
149        int i;
150        usec1=usec;
151        if (!timer_init_done) {
152                return;
153        }
154        counter = read_pit();
155        ctr1 = counter;
156        wraps = usec/1000;
157        usec = usec%1000;
158
159        usec2 = usec;
160        wraps1 = wraps;
161
162        usec*=1194;
163        usec/=1000;
164        usec+=counter;
165        if (usec > 1194) {
166                usec-=1194;
167                wraps++;
168        }
169
170        usec3 = usec;
171        wraps2 = wraps;
172
173        ctr2 = wraps3 = nct1 = 4711;
174        ctr3 = wraps4 = nct2 = 4711;
175        i=0;
176        while (1) {
177                int new_count = read_pit();
178                i++;
179                if ((new_count < usec && !wraps) || wraps < 0) {
180                        break;
181                }
182
183                if (new_count > counter) {
184                        wraps--;
185                }
186                if (ctr2==4711) {
187                        ctr2 = counter;
188                        wraps3 = wraps;
189                        nct1 = new_count;
190                } else {
191                        ctr3 = counter;
192                        wraps4 = wraps;
193                        nct2 = new_count;
194                }
195
196                counter = new_count;
197        }
198
199        printf("udelay(%d)\n", usec1);
200        printf("counter %d\n", ctr1);
201        printf("1: wraps %d, usec %d\n", wraps1, usec2);
202        printf("2: wraps %d, usec %d\n", wraps2, usec3);
203        printf("new_count[0] %d counter %d wraps %d\n", nct1, ctr2, wraps3);
204        printf("new_count[%d] %d counter %d wraps %d\n", i, nct2, ctr3, wraps4);
205
206        printf("%d %d %d %d %d\n",
207               read_pit(), read_pit(), read_pit(),
208               read_pit(), read_pit());
209}
210#endif
211#endif
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