Kernel/arch/x86/time.c

   1 /*
   2  * Acess2 Kernel
   3  * Timekeeping
   4  * arch/x86/time.c
   5  */
   6 #include <acess.h>
   7
   8 // === MACROS ===
   9 #define TIMER_QUANTUM   100
  10 // 2^(15-rate), 15: 1HZ, 5: 1024Hz, 2: 8192Hz
  11 #define TIMER_RATE      12      // (Max: 15, Min: 2) - 15 = 1Hz, 13 = 4Hz, 12 = 8Hz, 11 = 16Hz 10 = 32Hz, 2
  12 #define TIMER_FREQ      (0x8000>>TIMER_RATE)    //Hz
  13 #define MS_PER_TICK_WHOLE       (1000/(TIMER_FREQ))
  14 #define MS_PER_TICK_FRACT       ((Uint64)(1000*TIMER_FREQ-((Uint64)MS_PER_TICK_WHOLE)*0x80000000/TIMER_FREQ))
  15
  16 // === IMPORTS ===
  17 extern Sint64   giTimestamp;
  18 extern Uint64   giTicks;
  19 extern Uint64   giPartMiliseconds;
  20
  21 // === PROTOTYPES ===
  22 void    Time_Interrupt();
  23
  24 // === CODE ===
  25 /**
  26  * \fn int Time_Setup()
  27  * \brief Sets the system time from the Realtime-Clock
  28  */
  29 int Time_Setup()
  30 {
  31         Uint8   val;
  32
  33         outb(0x70, inb(0x70)&0x7F);     // Disable NMIs
  34         __asm__ __volatile__ ("cli");   // Disable normal interrupts
  35
  36         // Set IRQ8 firing rate
  37         outb(0x70, 0x0A);       // Set the index to register A
  38         val = inb(0x71); // Get the current value of register A
  39         outb(0x70, 0x0A); // Reset index to A
  40         val &= 0xF0;
  41         val |= TIMER_RATE;
  42         outb(0x71, val);        // Update the timer rate
  43
  44         // Enable IRQ8
  45         outb(0x70, 0x0B);       // Set the index to register B
  46         val = inb(0x71);        // Read the current value of register B
  47         outb(0x70, 0x0B);       // Set the index again (a read will reset the index to register D)
  48         outb(0x71, val | 0x40); // Write the previous value or'd with 0x40. This turns on bit 6 of register D
  49
  50         __asm__ __volatile__ ("sti");   // Disable normal interrupts
  51         outb(0x70, inb(0x70)|0x80);     // Disable NMIs
  52
  53         // Install IRQ Handler
  54         IRQ_AddHandler(8, Time_Interrupt);
  55         return 0;
  56 }
  57
  58 /**
  59  * \fn void Time_Interrupt()
  60  * \brief Called on the timekeeping IRQ
  61  */
  62 void Time_Interrupt()
  63 {
  64         giTicks ++;
  65         giTimestamp += MS_PER_TICK_WHOLE;
  66         giPartMiliseconds += MS_PER_TICK_FRACT;
  67         if(giPartMiliseconds > 0x80000000) {
  68                 giTimestamp ++;
  69                 giPartMiliseconds -= 0x80000000;
  70         }
  71
  72         Timer_CallTimers();
  73
  74         // Make sure the RTC Fires again
  75         outb(0x70, 0x0C); // Select register C
  76         inb(0x71);      // Just throw away contents.
  77 }
  78
  79 #if 0
  80 /**
  81  * \fn void Time_TimerThread()
  82  */
  83 void Time_TimerThread()
  84 {
  85         Sint64  next;
  86         Threads_SetName("TIMER");
  87
  88         next = giTimestamp + TIMER_QUANTUM;
  89         for(;;)
  90         {
  91                 while(giTimestamp < next)       Threads_Yield();
  92                 next = giTimestamp + TIMER_QUANTUM;
  93                 Timer_CallTimers();
  94         }
  95 }
  96 #endif