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/* Defines for routines to implement a low-overhead timer for drivers */
/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2, or (at
* your option) any later version.
*/
#ifndef TIMER_H
#define TIMER_H
/* Ports for the 8254 timer chip */
#define TIMER2_PORT 0x42
#define TIMER_MODE_PORT 0x43
/* Meaning of the mode bits */
#define TIMER0_SEL 0x00
#define TIMER1_SEL 0x40
#define TIMER2_SEL 0x80
#define READBACK_SEL 0xC0
#define LATCH_COUNT 0x00
#define LOBYTE_ACCESS 0x10
#define HIBYTE_ACCESS 0x20
#define WORD_ACCESS 0x30
#define MODE0 0x00
#define MODE1 0x02
#define MODE2 0x04
#define MODE3 0x06
#define MODE4 0x08
#define MODE5 0x0A
#define BINARY_COUNT 0x00
#define BCD_COUNT 0x01
/* Timers tick over at this rate */
#define TICKS_PER_MS 1193
/* Parallel Peripheral Controller Port B */
#define PPC_PORTB 0x61
/* Meaning of the port bits */
#define PPCB_T2OUT 0x20 /* Bit 5 */
#define PPCB_SPKR 0x02 /* Bit 1 */
#define PPCB_T2GATE 0x01 /* Bit 0 */
/* Ticks must be between 0 and 65535 (0 == 65536)
because it is a 16 bit counter */
extern void load_timer2(unsigned int ticks);
extern inline int timer2_running(void)
{
return ((inb(PPC_PORTB) & PPCB_T2OUT) == 0);
}
extern inline void waiton_timer2(unsigned int ticks)
{
load_timer2(ticks);
while ((inb(PPC_PORTB) & PPCB_T2OUT) == 0)
;
}
#endif /* TIMER_H */
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