/* 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 */