xref: /openbmc/u-boot/arch/x86/lib/i8254.c (revision 308b1307)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * (C) Copyright 2002
4  * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
5  */
6 
7 #include <common.h>
8 #include <asm/io.h>
9 #include <asm/i8254.h>
10 
11 #define TIMER1_VALUE		18	/* 15.6us */
12 #define BEEP_FREQUENCY_HZ	440
13 #define SYSCTL_PORTB		0x61
14 #define PORTB_BEEP_ENABLE	0x3
15 
16 static void i8254_set_beep_freq(uint frequency_hz)
17 {
18 	uint countdown;
19 
20 	countdown = PIT_TICK_RATE / frequency_hz;
21 
22 	outb(countdown & 0xff, PIT_BASE + PIT_T2);
23 	outb((countdown >> 8) & 0xff, PIT_BASE + PIT_T2);
24 }
25 
26 int i8254_init(void)
27 {
28 	/*
29 	 * Initialize counter 1, used to refresh request signal.
30 	 * This is required for legacy purpose as some codes like
31 	 * vgabios utilizes counter 1 to provide delay functionality.
32 	 */
33 	outb(PIT_CMD_CTR1 | PIT_CMD_LOW | PIT_CMD_MODE2,
34 	     PIT_BASE + PIT_COMMAND);
35 	outb(TIMER1_VALUE, PIT_BASE + PIT_T1);
36 
37 	/*
38 	 * Initialize counter 2, used to drive the speaker.
39 	 * To start a beep, set both bit0 and bit1 of port 0x61.
40 	 * To stop it, clear both bit0 and bit1 of port 0x61.
41 	 */
42 	outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
43 	     PIT_BASE + PIT_COMMAND);
44 	i8254_set_beep_freq(BEEP_FREQUENCY_HZ);
45 
46 	return 0;
47 }
48 
49 int i8254_enable_beep(uint frequency_hz)
50 {
51 	if (!frequency_hz)
52 		return -EINVAL;
53 
54 	/* make sure i8254 is setup correctly before generating beeps */
55 	outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
56 	     PIT_BASE + PIT_COMMAND);
57 
58 	i8254_set_beep_freq(frequency_hz);
59 	setio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE);
60 
61 	return 0;
62 }
63 
64 void i8254_disable_beep(void)
65 {
66 	clrio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE);
67 }
68