u-boot/arch/x86/lib/pcat_timer.c

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/*
* (C) Copyright 2002
* Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <asm/io.h>
#include <asm/i8254.h>
#define TIMER2_VALUE 0x0a8e /* 440Hz */
int pcat_timer_init(void)
{
/*
* initialize 2, used to drive the speaker
* (to start a beep: write 3 to port 0x61,
* to stop it again: write 0)
*/
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);
return 0;
}