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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 TIMER2_VALUE	0x0a8e	/* 440Hz */
13 
i8254_init(void)14 int i8254_init(void)
15 {
16 	/*
17 	 * Initialize counter 1, used to refresh request signal.
18 	 * This is required for legacy purpose as some codes like
19 	 * vgabios utilizes counter 1 to provide delay functionality.
20 	 */
21 	outb(PIT_CMD_CTR1 | PIT_CMD_LOW | PIT_CMD_MODE2,
22 	     PIT_BASE + PIT_COMMAND);
23 	outb(TIMER1_VALUE, PIT_BASE + PIT_T1);
24 
25 	/*
26 	 * Initialize counter 2, used to drive the speaker.
27 	 * To start a beep, set both bit0 and bit1 of port 0x61.
28 	 * To stop it, clear both bit0 and bit1 of port 0x61.
29 	 */
30 	outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
31 	     PIT_BASE + PIT_COMMAND);
32 	outb(TIMER2_VALUE & 0xff, PIT_BASE + PIT_T2);
33 	outb(TIMER2_VALUE >> 8, PIT_BASE + PIT_T2);
34 
35 	return 0;
36 }
37