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 // (Max: 15, Min: 2) - 15 = 1Hz, 13 = 4Hz, 12 = 8Hz, 11 = 16Hz 10 = 32Hz, 2 = 8192Hz
  12 #define TIMER_RATE      12
  13 //#define TIMER_RATE    15
  14 #define TIMER_FREQ      (0x8000>>TIMER_RATE)    //Hz
  15 #define MS_PER_TICK_WHOLE       (1000/(TIMER_FREQ))
  16 #define MS_PER_TICK_FRACT       ((0x80000000*(1000%TIMER_FREQ))/TIMER_FREQ)
  17
  18 // === IMPORTS ===
  19 extern Sint64   giTimestamp;
  20 extern Uint64   giTicks;
  21 extern Uint64   giPartMiliseconds;
  22 extern void     Timer_CallTimers(void);
  23
  24 // === PROTOTYPES ===
  25 void    Time_Interrupt(int);
  26
  27 // === CODE ===
  28 /**
  29  * \fn int Time_Setup(void)
  30  * \brief Sets the system time from the Realtime-Clock
  31  */
  32 int Time_Setup(void)
  33 {
  34         Uint8   val;
  35
  36         Log_Log("Timer", "RTC Timer firing at %iHz (%i divisor), %i.0x%08x",
  37                 TIMER_FREQ, TIMER_RATE, MS_PER_TICK_WHOLE, MS_PER_TICK_FRACT);
  38
  39         outb(0x70, inb(0x70)&0x7F);     // Disable NMIs
  40         __asm__ __volatile__ ("cli");   // Disable normal interrupts
  41
  42         // Set IRQ8 firing rate
  43         outb(0x70, 0x0A);       // Set the index to register A
  44         val = inb(0x71); // Get the current value of register A
  45         outb(0x70, 0x0A); // Reset index to A
  46         val &= 0xF0;
  47         val |= TIMER_RATE;
  48         outb(0x71, val);        // Update the timer rate
  49
  50         // Enable IRQ8
  51         outb(0x70, 0x0B);       // Set the index to register B
  52         val = inb(0x71);        // Read the current value of register B
  53         outb(0x70, 0x0B);       // Set the index again (a read will reset the index to register D)
  54         outb(0x71, val | 0x40); // Write the previous value or'd with 0x40. This turns on bit 6 of register D
  55
  56         __asm__ __volatile__ ("sti");   // Re-enable normal interrupts
  57         outb(0x70, inb(0x70)|0x80);     // Re-enable NMIs
  58
  59         // Install IRQ Handler
  60         IRQ_AddHandler(8, Time_Interrupt);
  61
  62         // Make sure the RTC actually fires
  63         outb(0x70, 0x0C); // Select register C
  64         inb(0x71);      // Just throw away contents.
  65
  66         return 0;
  67 }
  68
  69 /**
  70  * \brief Called on the timekeeping IRQ
  71  * \param irq   IRQ number (unused)
  72  */
  73 void Time_Interrupt(int irq)
  74 {
  75         //Log("RTC Tick");
  76
  77         giTicks ++;
  78         giTimestamp += MS_PER_TICK_WHOLE;
  79         giPartMiliseconds += MS_PER_TICK_FRACT;
  80         if(giPartMiliseconds > 0x80000000) {
  81                 giTimestamp ++;
  82                 giPartMiliseconds -= 0x80000000;
  83         }
  84
  85         Timer_CallTimers();
  86
  87         // Make sure the RTC Fires again
  88         outb(0x70, 0x0C); // Select register C
  89         inb(0x71);      // Just throw away contents.
  90 }
  91
  92 #if 0
  93 /**
  94  * \fn void Time_TimerThread(void)
  95  */
  96 void Time_TimerThread(void)
  97 {
  98         Sint64  next;
  99         Threads_SetName("TIMER");
 100
 101         next = giTimestamp + TIMER_QUANTUM;
 102         for(;;)
 103         {
 104                 while(giTimestamp < next)       Threads_Yield();
 105                 next = giTimestamp + TIMER_QUANTUM;
 106                 Timer_CallTimers();
 107         }
 108 }
 109 #endif