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36 lines
964 B
36 lines
964 B
// 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, <[email protected]> |
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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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