mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-27 07:01:24 +00:00
106 lines
2.4 KiB
C
106 lines
2.4 KiB
C
/*
|
|
* (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>
|
|
#include <asm/interrupt.h>
|
|
|
|
#define TIMER0_VALUE 0x04aa /* 1kHz 1.9318MHz / 1000 */
|
|
#define TIMER2_VALUE 0x0a8e /* 440Hz */
|
|
|
|
static int timer_init_done;
|
|
|
|
int timer_init(void)
|
|
{
|
|
/* 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);
|
|
|
|
irq_install_handler(0, timer_isr, NULL);
|
|
unmask_irq(0);
|
|
|
|
timer_init_done = 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
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) {
|
|
counter = read_pit();
|
|
wraps = usec / 1000;
|
|
usec = usec % 1000;
|
|
|
|
usec *= 1194;
|
|
usec /= 1000;
|
|
usec += counter;
|
|
|
|
while (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;
|
|
}
|
|
}
|
|
|
|
}
|