arch/m68k-amiga/kernel/kernel_timer.c

   1 /*
   2  * This code probes Amiga hardware timings, and
   3  * configures SysBase with those settings.
   4  */
   5
   6 #include <aros/symbolsets.h>
   7 #include <exec/execbase.h>
   8 #include <proto/exec.h>
   9 #include <hardware/cia.h>
  10
  11 #include <kernel_base.h>
  12
  13 static int Timer_Init(struct KernelBase *KernelBase)
  14 {
  15     volatile struct CIA *ciaa = (struct CIA*)0xbfe001;
  16     UWORD todlo, todcnt;
  17
  18     /*
  19      * Check powersupply tick rate.
  20      * No Disable() here because we are running without interrupts during early init.
  21      */
  22     ciaa->ciacra = 0x00;
  23     ciaa->ciatodhi = 0;
  24     ciaa->ciatodmid = 0;
  25     ciaa->ciatodlow = 0;
  26     ciaa->ciatalo = 0xff;
  27     ciaa->ciatahi = 0xff;
  28     todlo = ciaa->ciatodlow;
  29     while (todlo == ciaa->ciatodlow);
  30     ciaa->ciacra = 0x01;
  31     todlo = ciaa->ciatodlow;
  32     while (todlo == ciaa->ciatodlow);
  33     ciaa->ciacra = 0x00;
  34     todcnt = ~(((ciaa->ciatahi << 8) | ciaa->ciatalo) + 1);
  35
  36     /*
  37      * 50Hz/60Hz ticks:
  38      * 50Hz PAL  14188
  39      * 60Hz NTSC 11932
  40      * 50Hz NTSC 14318
  41      * 60Hz PAL  11823
  42      */
  43     if (todcnt > 14188 + (14318 - 14188) / 2)
  44         SysBase->PowerSupplyFrequency = 50;
  45     else if (todcnt <= 11823 + (11932 - 11823) / 2)
  46         SysBase->PowerSupplyFrequency = 60;
  47     else if (todcnt > 14188 - (14188 - 11932) / 2)
  48         SysBase->PowerSupplyFrequency = 50;
  49     else
  50         SysBase->PowerSupplyFrequency = 60;
  51
  52     return TRUE;
  53 }
  54
  55 ADD2INITLIB(Timer_Init, 0)