37 lines
964 B
C
37 lines
964 B
C
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// SPDX-License-Identifier: GPL-2.0+
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/*
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* (C) Copyright 2002
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* Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
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*/
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#include <common.h>
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#include <asm/io.h>
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#include <asm/i8254.h>
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#define TIMER1_VALUE 18 /* 15.6us */
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#define TIMER2_VALUE 0x0a8e /* 440Hz */
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int i8254_init(void)
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{
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/*
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* Initialize counter 1, used to refresh request signal.
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* This is required for legacy purpose as some codes like
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* vgabios utilizes counter 1 to provide delay functionality.
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*/
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outb(PIT_CMD_CTR1 | PIT_CMD_LOW | PIT_CMD_MODE2,
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PIT_BASE + PIT_COMMAND);
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outb(TIMER1_VALUE, PIT_BASE + PIT_T1);
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/*
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* Initialize counter 2, used to drive the speaker.
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* To start a beep, set both bit0 and bit1 of port 0x61.
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* To stop it, clear both bit0 and bit1 of port 0x61.
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*/
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outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
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PIT_BASE + PIT_COMMAND);
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outb(TIMER2_VALUE & 0xff, PIT_BASE + PIT_T2);
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outb(TIMER2_VALUE >> 8, PIT_BASE + PIT_T2);
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return 0;
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}
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