Kernel/arch/x86/time.c

   1 /*
   2  * Acess2 Kernel
   3  * Timekeeping
   4  * arch/x86/time.c
   5  */
   6 #include <common.h>
   7
   8 // === MACROS ===
   9 #define NUM_TIMERS      8
  10 #define TIMER_QUANTUM   100
  11 #define TIMER_FREQ      1024    //Hz
  12 #define MS_PER_TICK_WHOLE       (1000/(TIMER_FREQ))
  13 #define MS_PER_TICK_FRACT       ((Uint64)(1000*TIMER_FREQ-((Uint64)MS_PER_TICK_WHOLE)*0x80000000/TIMER_FREQ))
  14
  15 // === TYPEDEFS ===
  16 typedef struct sTimer {
  17          int    FiresAfter;
  18         void    (*Callback)(void*);
  19         void    *Argument;
  20 } tTimer;
  21
  22 // === PROTOTYPES ===
  23 void    Time_Interrupt();
  24 void    Timer_CallTimers();
  25
  26 // === GLOBALS ===
  27 Uint64  giTicks = 0;
  28 Sint64  giTimestamp = 0;
  29 Uint64  giPartMiliseconds = 0;
  30 tTimer  gTimers[NUM_TIMERS];
  31
  32 // === CODE ===
  33 /**
  34  * \fn int Time_Setup()
  35  * \brief Sets the system time from the Realtime-Clock
  36  */
  37 int Time_Setup()
  38 {
  39         Uint8   val;
  40
  41         outb(0x70, inb(0x70)&0x7F);     // Disable NMIs
  42         __asm__ __volatile__ ("cli");   // Disable normal interrupts
  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
  75 /**
  76  * \fn void Time_TimerThread()
  77  */
  78 #if 0
  79 void Time_TimerThread()
  80 {
  81         Sint64  next;
  82         Threads_SetName("TIMER");
  83
  84         next = giTimestamp + TIMER_QUANTUM;
  85         for(;;)
  86         {
  87                 while(giTimestamp < next)       Threads_Yield();
  88                 next = giTimestamp + TIMER_QUANTUM;
  89                 Timer_CallTimers();
  90         }
  91 }
  92 #endif
  93
  94 /**
  95  * \fn Sint64 now()
  96  * \brief Return the current timestamp
  97  */
  98 Sint64 now()
  99 {
 100         return giTimestamp;
 101 }
 102
 103 /**
 104  * \fn void Timer_CallTimers()
 105  */
 106 void Timer_CallTimers()
 107 {
 108          int    i;
 109         void    (*callback)(void *);
 110
 111         for(i = 0;
 112                 i < NUM_TIMERS;
 113                 i ++)
 114         {
 115                 if(gTimers[i].Callback == NULL) continue;
 116                 if(giTimestamp < gTimers[i].FiresAfter) continue;
 117                 callback = gTimers[i].Callback;
 118                 gTimers[i].Callback = NULL;
 119                 callback(gTimers[i].Argument);
 120         }
 121 }
 122
 123 /**
 124  * \fn int Time_CreateTimer(int Delta, void *Callback, void *Argument)
 125  */
 126 int Time_CreateTimer(int Delta, void *Callback, void *Argument)
 127 {
 128          int    ret;
 129         for(ret = 0;
 130                 ret < NUM_TIMERS;
 131                 ret++)
 132         {
 133                 if(gTimers[ret].Callback != NULL)       continue;
 134                 gTimers[ret].Callback = Callback;
 135                 gTimers[ret].FiresAfter = giTimestamp + Delta;
 136                 gTimers[ret].Argument = Argument;
 137                 return ret;
 138         }
 139         return -1;
 140 }
 141
 142 /**
 143  * \fn void Time_RemoveTimer(int ID)
 144  */
 145 void Time_RemoveTimer(int ID)
 146 {
 147         if(ID < 0 || ID >= NUM_TIMERS)  return;
 148         gTimers[ID].Callback = NULL;
 149 }
 150
 151 /**
 152  * \fn void Time_Delay(int Delay)
 153  * \brief Delay for a small ammount of time
 154  */
 155 void Time_Delay(int Delay)
 156 {
 157         Sint64  dest = giTimestamp + Delay;
 158         while(dest < giTimestamp)       Threads_Yield();
 159 }