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// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2002
* Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
*/
#include <common.h>
#include <asm/io.h>
#include <asm/i8254.h>
#define TIMER1_VALUE 18 /* 15.6us */
#define BEEP_FREQUENCY_HZ 440
#define SYSCTL_PORTB 0x61
#define PORTB_BEEP_ENABLE 0x3
static void i8254_set_beep_freq(uint frequency_hz)
{
uint countdown;
countdown = PIT_TICK_RATE / frequency_hz;
outb(countdown & 0xff, PIT_BASE + PIT_T2);
outb((countdown >> 8) & 0xff, PIT_BASE + PIT_T2);
}
int i8254_init(void)
{
/*
* Initialize counter 1, used to refresh request signal.
* This is required for legacy purpose as some codes like
* vgabios utilizes counter 1 to provide delay functionality.
*/
outb(PIT_CMD_CTR1 | PIT_CMD_LOW | PIT_CMD_MODE2,
PIT_BASE + PIT_COMMAND);
outb(TIMER1_VALUE, PIT_BASE + PIT_T1);
/*
* Initialize counter 2, used to drive the speaker.
* To start a beep, set both bit0 and bit1 of port 0x61.
* To stop it, clear both bit0 and bit1 of port 0x61.
*/
outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
PIT_BASE + PIT_COMMAND);
i8254_set_beep_freq(BEEP_FREQUENCY_HZ);
return 0;
}
int i8254_enable_beep(uint frequency_hz)
{
if (!frequency_hz)
return -EINVAL;
/* make sure i8254 is setup correctly before generating beeps */
outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
PIT_BASE + PIT_COMMAND);
i8254_set_beep_freq(frequency_hz);
setio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE);
return 0;
}
void i8254_disable_beep(void)
{
clrio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE);
}
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