1/* Defines for routines to implement a low-overhead timer for drivers */ 2 3 /* 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation; either version 2, or (at 7 * your option) any later version. 8 */ 9 10#ifndef TIMER_H 11#define TIMER_H 12 13/* Ports for the 8254 timer chip */ 14#define TIMER2_PORT 0x42 15#define TIMER_MODE_PORT 0x43 16 17/* Meaning of the mode bits */ 18#define TIMER0_SEL 0x00 19#define TIMER1_SEL 0x40 20#define TIMER2_SEL 0x80 21#define READBACK_SEL 0xC0 22 23#define LATCH_COUNT 0x00 24#define LOBYTE_ACCESS 0x10 25#define HIBYTE_ACCESS 0x20 26#define WORD_ACCESS 0x30 27 28#define MODE0 0x00 29#define MODE1 0x02 30#define MODE2 0x04 31#define MODE3 0x06 32#define MODE4 0x08 33#define MODE5 0x0A 34 35#define BINARY_COUNT 0x00 36#define BCD_COUNT 0x01 37 38/* Timers tick over at this rate */ 39#define TICKS_PER_MS 1193 40 41/* Parallel Peripheral Controller Port B */ 42#define PPC_PORTB 0x61 43 44/* Meaning of the port bits */ 45#define PPCB_T2OUT 0x20 /* Bit 5 */ 46#define PPCB_SPKR 0x02 /* Bit 1 */ 47#define PPCB_T2GATE 0x01 /* Bit 0 */ 48 49/* Ticks must be between 0 and 65535 (0 == 65536) 50 because it is a 16 bit counter */ 51extern void load_timer2(unsigned int ticks); 52extern inline int timer2_running(void) 53{ 54 return ((inb(PPC_PORTB) & PPCB_T2OUT) == 0); 55} 56 57extern inline void waiton_timer2(unsigned int ticks) 58{ 59 load_timer2(ticks); 60 while ((inb(PPC_PORTB) & PPCB_T2OUT) == 0) 61 ; 62} 63 64#endif /* TIMER_H */ 65