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       ((0x80000000*(1000%TIMER_FREQ))/TIMER_FREQ)
  15
  16 // === IMPORTS ===
  17 extern Sint64   giTimestamp;
  18 extern Uint64   giTicks;
  19 extern Uint64   giPartMiliseconds;
  20 extern void     Timer_CallTimers(void);
  21
  22 // === PROTOTYPES ===
  23 void    Time_Interrupt(int);
  24
  25 // === CODE ===
  26 /**
  27  * \fn int Time_Setup(void)
  28  * \brief Sets the system time from the Realtime-Clock
  29  */
  30 int Time_Setup(void)
  31 {
  32         Uint8   val;
  33
  34         Log_Log("Timer", "RTC Timer firing at %iHz (%i divisor), %i.0x%08x",
  35                 TIMER_FREQ, TIMER_RATE, MS_PER_TICK_WHOLE, MS_PER_TICK_FRACT);
  36
  37         outb(0x70, inb(0x70)&0x7F);     // Disable NMIs
  38         __asm__ __volatile__ ("cli");   // Disable normal interrupts
  39
  40         // Set IRQ8 firing rate
  41         outb(0x70, 0x0A);       // Set the index to register A
  42         val = inb(0x71); // Get the current value of register A
  43         outb(0x70, 0x0A); // Reset index to A
  44         val &= 0xF0;
  45         val |= TIMER_RATE;
  46         outb(0x71, val);        // Update the timer rate
  47
  48         // Enable IRQ8
  49         outb(0x70, 0x0B);       // Set the index to register B
  50         val = inb(0x71);        // Read the current value of register B
  51         outb(0x70, 0x0B);       // Set the index again (a read will reset the index to register D)
  52         outb(0x71, val | 0x40); // Write the previous value or'd with 0x40. This turns on bit 6 of register D
  53
  54         __asm__ __volatile__ ("sti");   // Disable normal interrupts
  55         outb(0x70, inb(0x70)|0x80);     // Disable NMIs
  56
  57         // Install IRQ Handler
  58         IRQ_AddHandler(8, Time_Interrupt);
  59
  60         // Make sure the RTC actually fires
  61         outb(0x70, 0x0C); // Select register C
  62         inb(0x71);      // Just throw away contents.
  63
  64         return 0;
  65 }
  66
  67 /**
  68  * \fn void Time_Interrupt(void)
  69  * \brief Called on the timekeeping IRQ
  70  */
  71 void Time_Interrupt(int irq)
  72 {
  73         giTicks ++;
  74         giTimestamp += MS_PER_TICK_WHOLE;
  75         giPartMiliseconds += MS_PER_TICK_FRACT;
  76         if(giPartMiliseconds > 0x80000000) {
  77                 giTimestamp ++;
  78                 giPartMiliseconds -= 0x80000000;
  79         }
  80
  81         Timer_CallTimers();
  82
  83         // Make sure the RTC Fires again
  84         outb(0x70, 0x0C); // Select register C
  85         inb(0x71);      // Just throw away contents.
  86 }
  87
  88 #if 0
  89 /**
  90  * \fn void Time_TimerThread(void)
  91  */
  92 void Time_TimerThread(void)
  93 {
  94         Sint64  next;
  95         Threads_SetName("TIMER");
  96
  97         next = giTimestamp + TIMER_QUANTUM;
  98         for(;;)
  99         {
 100                 while(giTimestamp < next)       Threads_Yield();
 101                 next = giTimestamp + TIMER_QUANTUM;
 102                 Timer_CallTimers();
 103         }
 104 }
 105 #endif