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 */ 51 extern void load_timer2(unsigned int ticks); 52 extern inline int timer2_running(void) 53 { 54 return ((inb(PPC_PORTB) & PPCB_T2OUT) == 0); 55 } 56 57 extern 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
