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62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
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/* Defines for routines to implement a low-overhead timer for drivers */
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/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2, or (at
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* your option) any later version.
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*/
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#ifndef TIMER_H
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#define TIMER_H
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/* Ports for the 8254 timer chip */
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#define TIMER2_PORT 0x42
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#define TIMER_MODE_PORT 0x43
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/* Meaning of the mode bits */
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#define TIMER0_SEL 0x00
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#define TIMER1_SEL 0x40
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#define TIMER2_SEL 0x80
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#define READBACK_SEL 0xC0
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#define LATCH_COUNT 0x00
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#define LOBYTE_ACCESS 0x10
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#define HIBYTE_ACCESS 0x20
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#define WORD_ACCESS 0x30
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#define MODE0 0x00
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#define MODE1 0x02
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#define MODE2 0x04
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#define MODE3 0x06
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#define MODE4 0x08
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#define MODE5 0x0A
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#define BINARY_COUNT 0x00
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#define BCD_COUNT 0x01
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/* Timers tick over at this rate */
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#define CLOCK_TICK_RATE 1193180U
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#define TICKS_PER_MS (CLOCK_TICK_RATE/1000)
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/* Parallel Peripheral Controller Port B */
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#define PPC_PORTB 0x61
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/* Meaning of the port bits */
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#define PPCB_T2OUT 0x20 /* Bit 5 */
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#define PPCB_SPKR 0x02 /* Bit 1 */
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#define PPCB_T2GATE 0x01 /* Bit 0 */
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/* Ticks must be between 0 and 65535 (0 == 65536)
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because it is a 16 bit counter */
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extern void load_timer2(unsigned int ticks);
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extern inline int timer2_running(void);
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extern void waiton_timer2(unsigned int ticks);
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extern void ndelay(unsigned int nsecs);
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extern void udelay(unsigned int usecs);
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extern void mdelay(unsigned int msecs);
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#endif /* TIMER_H */
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