diff options
Diffstat (limited to 'cpu/i386/timer.c')
| -rw-r--r-- | cpu/i386/timer.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/cpu/i386/timer.c b/cpu/i386/timer.c new file mode 100644 index 0000000..a23cd6e --- /dev/null +++ b/cpu/i386/timer.c @@ -0,0 +1,211 @@ +/* + * (C) Copyright 2002 + * Daniel Engström, Omicron Ceti AB, daniel@omicron.se. + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +#include <common.h> +#include <asm/io.h> +#include <asm/i8254.h> +#include <asm/ibmpc.h> + + +static volatile unsigned long system_ticks; +static int timer_init_done =0; + +static void timer_isr(void *unused) +{ + system_ticks++; +} + +unsigned long get_system_ticks(void) +{ + return system_ticks; +} + +#define TIMER0_VALUE 0x04aa /* 1kHz 1.9318MHz / 1000 */ +#define TIMER2_VALUE 0x0a8e /* 440Hz */ + +int timer_init(void) +{ + system_ticks = 0; + + irq_install_handler(0, timer_isr, NULL); + + /* initialize timer 0 and 2 + * + * Timer 0 is used to increment system_tick 1000 times/sec + * Timer 1 was used for DRAM refresh in early PC's + * Timer 2 is used to drive the speaker + * (to stasrt a beep: write 3 to port 0x61, + * to stop it again: write 0) + */ + + outb(PIT_CMD_CTR0|PIT_CMD_BOTH|PIT_CMD_MODE2, PIT_BASE + PIT_COMMAND); + outb(TIMER0_VALUE&0xff, PIT_BASE + PIT_T0); + outb(TIMER0_VALUE>>8, PIT_BASE + PIT_T0); + + outb(PIT_CMD_CTR2|PIT_CMD_BOTH|PIT_CMD_MODE3, PIT_BASE + PIT_COMMAND); + outb(TIMER2_VALUE&0xff, PIT_BASE + PIT_T2); + outb(TIMER2_VALUE>>8, PIT_BASE + PIT_T2); + + timer_init_done = 1; + + return 0; +} + + +#ifdef CFG_TIMER_GENERIC + +/* the unit for these is CFG_HZ */ + +/* FixMe: implement these */ +void reset_timer (void) +{ + system_ticks = 0; +} + +ulong get_timer (ulong base) +{ + return (system_ticks - base); +} + +void set_timer (ulong t) +{ + system_ticks = t; +} + +static u16 read_pit(void) +{ + u8 low; + outb(PIT_CMD_LATCH, PIT_BASE + PIT_COMMAND); + low = inb(PIT_BASE + PIT_T0); + return ((inb(PIT_BASE + PIT_T0) << 8) | low); +} + +/* this is not very exact */ +void udelay (unsigned long usec) +{ + int counter; + int wraps; + + if (!timer_init_done) { + return; + } + counter = read_pit(); + wraps = usec/1000; + usec = usec%1000; + + usec*=1194; + usec/=1000; + usec+=counter; + if (usec > 1194) { + usec-=1194; + wraps++; + } + + while (1) { + int new_count = read_pit(); + + if (((new_count < usec) && !wraps) || wraps < 0) { + break; + } + + if (new_count > counter) { + wraps--; + } + counter = new_count; + } + +} + +#if 0 +/* this is a version with debug output */ +void _udelay (unsigned long usec) +{ + int counter; + int wraps; + + int usec1, usec2, usec3; + int wraps1, wraps2, wraps3, wraps4; + int ctr1, ctr2, ctr3, nct1, nct2; + int i; + usec1=usec; + if (!timer_init_done) { + return; + } + counter = read_pit(); + ctr1 = counter; + wraps = usec/1000; + usec = usec%1000; + + usec2 = usec; + wraps1 = wraps; + + usec*=1194; + usec/=1000; + usec+=counter; + if (usec > 1194) { + usec-=1194; + wraps++; + } + + usec3 = usec; + wraps2 = wraps; + + ctr2 = wraps3 = nct1 = 4711; + ctr3 = wraps4 = nct2 = 4711; + i=0; + while (1) { + int new_count = read_pit(); + i++; + if ((new_count < usec && !wraps) || wraps < 0) { + break; + } + + if (new_count > counter) { + wraps--; + } + if (ctr2==4711) { + ctr2 = counter; + wraps3 = wraps; + nct1 = new_count; + } else { + ctr3 = counter; + wraps4 = wraps; + nct2 = new_count; + } + + counter = new_count; + } + + printf("udelay(%d)\n", usec1); + printf("counter %d\n", ctr1); + printf("1: wraps %d, usec %d\n", wraps1, usec2); + printf("2: wraps %d, usec %d\n", wraps2, usec3); + printf("new_count[0] %d counter %d wraps %d\n", nct1, ctr2, wraps3); + printf("new_count[%d] %d counter %d wraps %d\n", i, nct2, ctr3, wraps4); + + printf("%d %d %d %d %d\n", + read_pit(), read_pit(), read_pit(), + read_pit(), read_pit()); +} +#endif +#endif |