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