arch/common/boot/grub/netboot/timer.h

   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 */