arch/m68k-amiga/kernel/kernel_timer.c

   1 /*
   2     Copyright © 1995-2014, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 /*
   7  * This code probes Amiga hardware timings, and
   8  * configures SysBase with those settings.
   9  */
  10
  11 #include <aros/symbolsets.h>
  12 #include <exec/execbase.h>
  13 #include <proto/exec.h>
  14 #include <hardware/cia.h>
  15
  16 #include <kernel_base.h>
  17
  18 static int Timer_Init(struct KernelBase *KernelBase)
  19 {
  20     volatile struct CIA *ciaa = (struct CIA*)0xbfe001;
  21     UWORD todlo, todcnt;
  22
  23     /*
  24      * Check powersupply tick rate.
  25      * No Disable() here because we are running without interrupts during early init.
  26      */
  27     ciaa->ciacra = 0x00;
  28     ciaa->ciatodhi = 0;
  29     ciaa->ciatodmid = 0;
  30     ciaa->ciatodlow = 0;
  31     ciaa->ciatalo = 0xff;
  32     ciaa->ciatahi = 0xff;
  33     todlo = ciaa->ciatodlow;
  34     while (todlo == ciaa->ciatodlow);
  35     ciaa->ciacra = 0x01;
  36     todlo = ciaa->ciatodlow;
  37     while (todlo == ciaa->ciatodlow);
  38     ciaa->ciacra = 0x00;
  39     todcnt = ~(((ciaa->ciatahi << 8) | ciaa->ciatalo) + 1);
  40
  41     /*
  42      * 50Hz/60Hz ticks:
  43      * 50Hz PAL  14188
  44      * 60Hz NTSC 11932
  45      * 50Hz NTSC 14318
  46      * 60Hz PAL  11823
  47      */
  48     if (todcnt > 14188 + (14318 - 14188) / 2)
  49         SysBase->PowerSupplyFrequency = 50;
  50     else if (todcnt <= 11823 + (11932 - 11823) / 2)
  51         SysBase->PowerSupplyFrequency = 60;
  52     else if (todcnt > 14188 - (14188 - 11932) / 2)
  53         SysBase->PowerSupplyFrequency = 50;
  54     else
  55         SysBase->PowerSupplyFrequency = 60;
  56
  57     return TRUE;
  58 }
  59
  60 ADD2INITLIB(Timer_Init, 0)