43 lines
1.3 KiB
C
43 lines
1.3 KiB
C
/*
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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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* SPDX-License-Identifier: GPL-2.0+
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*/
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/* i8254.h Intel 8254 PIT registers */
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#ifndef _ASMI386_I8254_H_
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#define _ASMI386_I8954_H_ 1
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#define PIT_T0 0x00 /* PIT channel 0 count/status */
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#define PIT_T1 0x01 /* PIT channel 1 count/status */
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#define PIT_T2 0x02 /* PIT channel 2 count/status */
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#define PIT_COMMAND 0x03 /* PIT mode control, latch and read back */
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/* PIT Command Register Bit Definitions */
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#define PIT_CMD_CTR0 0x00 /* Select PIT counter 0 */
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#define PIT_CMD_CTR1 0x40 /* Select PIT counter 1 */
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#define PIT_CMD_CTR2 0x80 /* Select PIT counter 2 */
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#define PIT_CMD_LATCH 0x00 /* Counter Latch Command */
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#define PIT_CMD_LOW 0x10 /* Access counter bits 7-0 */
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#define PIT_CMD_HIGH 0x20 /* Access counter bits 15-8 */
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#define PIT_CMD_BOTH 0x30 /* Access counter bits 15-0 in two accesses */
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#define PIT_CMD_MODE0 0x00 /* Select mode 0 */
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#define PIT_CMD_MODE1 0x02 /* Select mode 1 */
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#define PIT_CMD_MODE2 0x04 /* Select mode 2 */
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#define PIT_CMD_MODE3 0x06 /* Select mode 3 */
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#define PIT_CMD_MODE4 0x08 /* Select mode 4 */
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#define PIT_CMD_MODE5 0x0A /* Select mode 5 */
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/* The clock frequency of the i8253/i8254 PIT */
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#define PIT_TICK_RATE 1193182ul
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#endif
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