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

/*
 * (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;
}